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Sample records for suppressing viral replication

  1. Adenovirus-encoding virus-associated RNAs suppress HDGF gene expression to support efficient viral replication.

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    Saki Kondo

    Full Text Available Non-coding small RNAs are involved in many physiological responses including viral life cycles. Adenovirus-encoding small RNAs, known as virus-associated RNAs (VA RNAs, are transcribed throughout the replication process in the host cells, and their transcript levels depend on the copy numbers of the viral genome. Therefore, VA RNAs are abundant in infected cells after genome replication, i.e. during the late phase of viral infection. Their function during the late phase is the inhibition of interferon-inducible protein kinase R (PKR activity to prevent antiviral responses; recently, mivaRNAs, the microRNAs processed from VA RNAs, have been reported to inhibit cellular gene expression. Although VA RNA transcription starts during the early phase, little is known about its function. The reason may be because much smaller amount of VA RNAs are transcribed during the early phase than the late phase. In this study, we applied replication-deficient adenovirus vectors (AdVs and novel AdVs lacking VA RNA genes to analyze the expression changes in cellular genes mediated by VA RNAs using microarray analysis. AdVs are suitable to examine the function of VA RNAs during the early phase, since they constitutively express VA RNAs but do not replicate except in 293 cells. We found that the expression level of hepatoma-derived growth factor (HDGF significantly decreased in response to the VA RNAs under replication-deficient condition, and this suppression was also observed during the early phase under replication-competent conditions. The suppression was independent of mivaRNA-induced downregulation, suggesting that the function of VA RNAs during the early phase differs from that during the late phase. Notably, overexpression of HDGF inhibited AdV growth. This is the first report to show the function, in part, of VA RNAs during the early phase that may be contribute to efficient viral growth.

  2. Suppression of Rac1 Signaling by Influenza A Virus NS1 Facilitates Viral Replication

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    Jiang, Wei; Sheng, Chunjie; Gu, Xiuling; Liu, Dong; Yao, Chen; Gao, Shijuan; Chen, Shuai; Huang, Yinghui; Huang, Wenlin; Fang, Min

    2016-01-01

    Influenza A virus (IAV) is a major human pathogen with the potential to become pandemic. IAV contains only eight RNA segments; thus, the virus must fully exploit the host cellular machinery to facilitate its own replication. In an effort to comprehensively characterize the host machinery taken over by IAV in mammalian cells, we generated stable A549 cell lines with over-expression of the viral non-structural protein (NS1) to investigate the potential host factors that might be modulated by the NS1 protein. We found that the viral NS1 protein directly interacted with cellular Rac1 and facilitated viral replication. Further research revealed that NS1 down-regulated Rac1 activity via post-translational modifications. Therefore, our results demonstrated that IAV blocked Rac1-mediated host cell signal transduction through the NS1 protein to facilitate its own replication. Our findings provide a novel insight into the mechanism of IAV replication and indicate new avenues for the development of potential therapeutic targets. PMID:27869202

  3. Pur-Alpha Induces JCV Gene Expression and Viral Replication by Suppressing SRSF1 in Glial Cells.

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    Ilker Kudret Sariyer

    Full Text Available PML is a rare and fatal demyelinating disease of the CNS caused by the human polyomavirus, JC virus (JCV, which occurs in AIDS patients and those on immunosuppressive monoclonal antibody therapies (mAbs. We sought to identify mechanisms that could stimulate reactivation of JCV in a cell culture model system and targeted pathways which could affect early gene transcription and JCV T-antigen production, which are key steps of the viral life cycle for blocking reactivation of JCV. Two important regulatory partners we have previously identified for T-antigen include Pur-alpha and SRSF1 (SF2/ASF. SRSF1, an alternative splicing factor, is a potential regulator of JCV whose overexpression in glial cells strongly suppresses viral gene expression and replication. Pur-alpha has been most extensively characterized as a sequence-specific DNA- and RNA-binding protein which directs both viral gene transcription and mRNA translation, and is a potent inducer of the JCV early promoter through binding to T-antigen.Pur-alpha and SRSF1 both act directly as transcriptional regulators of the JCV promoter and here we have observed that Pur-alpha is capable of ameliorating SRSF1-mediated suppression of JCV gene expression and viral replication. Interestingly, Pur-alpha exerted its effect by suppressing SRSF1 at both the protein and mRNA levels in glial cells suggesting this effect can occur independent of T-antigen. Pur-alpha and SRSF1 were both localized to oligodendrocyte inclusion bodies by immunohistochemistry in brain sections from patients with HIV-1 associated PML. Interestingly, inclusion bodies were typically positive for either Pur-alpha or SRSF1, though some cells appeared to be positive for both proteins.Taken together, these results indicate the presence of an antagonistic interaction between these two proteins in regulating of JCV gene expression and viral replication and suggests that they play an important role during viral reactivation leading to

  4. The proteasomal Rpn11 metalloprotease suppresses tombusvirus RNA recombination and promotes viral replication via facilitating assembly of the viral replicase complex.

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    Prasanth, K Reddisiva; Barajas, Daniel; Nagy, Peter D

    2015-03-01

    RNA viruses co-opt a large number of cellular proteins that affect virus replication and, in some cases, viral genetic recombination. RNA recombination helps viruses in an evolutionary arms race with the host's antiviral responses and adaptation of viruses to new hosts. Tombusviruses and a yeast model host are used to identify cellular factors affecting RNA virus replication and RNA recombination. In this study, we have examined the role of the conserved Rpn11p metalloprotease subunit of the proteasome, which couples deubiquitination and degradation of proteasome substrates, in tombusvirus replication and recombination in Saccharomyces cerevisiae and plants. Depletion or mutations of Rpn11p lead to the rapid formation of viral RNA recombinants in combination with reduced levels of viral RNA replication in yeast or in vitro based on cell extracts. Rpn11p interacts with the viral replication proteins and is recruited to the viral replicase complex (VRC). Analysis of the multifunctional Rpn11p has revealed that the primary role of Rpn11p is to act as a "matchmaker" that brings the viral p92(pol) replication protein and the DDX3-like Ded1p/RH20 DEAD box helicases into VRCs. Overexpression of Ded1p can complement the defect observed in rpn11 mutant yeast by reducing TBSV recombination. This suggests that Rpn11p can suppress tombusvirus recombination via facilitating the recruitment of the cellular Ded1p helicase, which is a strong suppressor of viral recombination, into VRCs. Overall, this work demonstrates that the co-opted Rpn11p, which is involved in the assembly of the functional proteasome, also functions in the proper assembly of the tombusvirus VRCs. RNA viruses evolve rapidly due to genetic changes based on mutations and RNA recombination. Viral genetic recombination helps viruses in an evolutionary arms race with the host's antiviral responses and facilitates adaptation of viruses to new hosts. Cellular factors affect viral RNA recombination, although the role

  5. Recombination-dependent concatemeric viral DNA replication.

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    Lo Piano, Ambra; Martínez-Jiménez, María I; Zecchi, Lisa; Ayora, Silvia

    2011-09-01

    The initiation of viral double stranded (ds) DNA replication involves proteins that recruit and load the replisome at the replication origin (ori). Any block in replication fork progression or a programmed barrier may act as a factor for ori-independent remodelling and assembly of a new replisome at the stalled fork. Then replication initiation becomes dependent on recombination proteins, a process called recombination-dependent replication (RDR). RDR, which is recognized as being important for replication restart and stability in all living organisms, plays an essential role in the replication cycle of many dsDNA viruses. The SPP1 virus, which infects Bacillus subtilis cells, serves as a paradigm to understand the links between replication and recombination in circular dsDNA viruses. SPP1-encoded initiator and replisome assembly proteins control the onset of viral replication and direct the recruitment of host-encoded replisomal components at viral oriL. SPP1 uses replication fork reactivation to switch from ori-dependent θ-type (circle-to-circle) replication to σ-type RDR. Replication fork arrest leads to a double strand break that is processed by viral-encoded factors to generate a D-loop into which a new replisome is assembled, leading to σ-type viral replication. SPP1 RDR proteins are compared with similar proteins encoded by other viruses and their possible in vivo roles are discussed. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Beyond viral suppression of HIV

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    Lazarus, Jeffrey V.; Safreed-Harmon, Kelly; Barton, Simon E

    2016-01-01

    BACKGROUND: In 2016, the World Health Organization (WHO) adopted a new Global Health Sector Strategy on HIV for 2016-2021. It establishes 15 ambitious targets, including the '90-90-90' target calling on health systems to reduce under-diagnosis of HIV, treat a greater number of those diagnosed......, and ensure that those being treated achieve viral suppression. DISCUSSION: The WHO strategy calls for person-centered chronic care for people living with HIV (PLHIV), implicitly acknowledging that viral suppression is not the ultimate goal of treatment. However, it stops short of providing an explicit target...... for health-related quality of life. It thus fails to take into account the needs of PLHIV who have achieved viral suppression but still must contend with other intense challenges such as serious non-communicable diseases, depression, anxiety, financial stress, and experiences of or apprehension about HIV...

  7. Suppression of Coronavirus Replication by Cyclophilin Inhibitors

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    Takashi Sasaki

    2013-05-01

    Full Text Available Coronaviruses infect a variety of mammalian and avian species and cause serious diseases in humans, cats, mice, and birds in the form of severe acute respiratory syndrome (SARS, feline infectious peritonitis (FIP, mouse hepatitis, and avian infectious bronchitis, respectively. No effective vaccine or treatment has been developed for SARS-coronavirus or FIP virus, both of which cause lethal diseases. It has been reported that a cyclophilin inhibitor, cyclosporin A (CsA, could inhibit the replication of coronaviruses. CsA is a well-known immunosuppressive drug that binds to cellular cyclophilins to inhibit calcineurin, a calcium-calmodulin-activated serine/threonine-specific phosphatase. The inhibition of calcineurin blocks the translocation of nuclear factor of activated T cells from the cytosol into the nucleus, thus preventing the transcription of genes encoding cytokines such as interleukin-2. Cyclophilins are peptidyl-prolyl isomerases with physiological functions that have been described for many years to include chaperone and foldase activities. Also, many viruses require cyclophilins for replication; these include human immunodeficiency virus, vesicular stomatitis virus, and hepatitis C virus. However, the molecular mechanisms leading to the suppression of viral replication differ for different viruses. This review describes the suppressive effects of CsA on coronavirus replication.

  8. Inhibitors of Nucleotidyltransferase Superfamily Enzymes Suppress Herpes Simplex Virus Replication

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    Wang, Hong; Tollefson, Ann E.; Ying, Baoling; Korom, Maria; Cheng, Xiaohong; Cao, Feng; Davis, Katie L.; Wold, William S. M.

    2014-01-01

    Herpesviruses are large double-stranded DNA viruses that cause serious human diseases. Herpesvirus DNA replication depends on multiple processes typically catalyzed by nucleotidyltransferase superfamily (NTS) enzymes. Therefore, we investigated whether inhibitors of NTS enzymes would suppress replication of herpes simplex virus 1 (HSV-1) and HSV-2. Eight of 42 NTS inhibitors suppressed HSV-1 and/or HSV-2 replication by >10-fold at 5 μM, with suppression at 50 μM reaching ∼1 million-fold. Five compounds in two chemical families inhibited HSV replication in Vero and human foreskin fibroblast cells as well as the approved drug acyclovir did. The compounds had 50% effective concentration values as low as 0.22 μM with negligible cytotoxicity in the assays employed. The inhibitors suppressed accumulation of viral genomes and infectious particles and blocked events in the viral replication cycle before and during viral DNA replication. Acyclovir-resistant mutants of HSV-1 and HSV-2 remained highly sensitive to the NTS inhibitors. Five of six NTS inhibitors of the HSVs also blocked replication of another herpesvirus pathogen, human cytomegalovirus. Therefore, NTS enzyme inhibitors are promising candidates for new herpesvirus treatments that may have broad efficacy against members of the herpesvirus family. PMID:25267681

  9. Lipid Tales of Viral Replication and Transmission.

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    Altan-Bonnet, Nihal

    2017-03-01

    Positive-strand RNA viruses are the largest group of RNA viruses on Earth and cellular membranes are critical for all aspects of their life cycle, from entry and replication to exit. In particular, membranes serve as platforms for replication and as carriers to transmit these viruses to other cells, the latter either as an envelope surrounding a single virus or as the vesicle containing a population of viruses. Notably, many animal and human viruses appear to induce and exploit phosphatidylinositol 4-phosphate/cholesterol-enriched membranes for replication, whereas many plant and insect-vectored animal viruses utilize phosphatidylethanolamine/cholesterol-enriched membranes for the same purpose; and phosphatidylserine-enriched membrane carriers are widely used by both single and populations of viruses for transmission. Here I discuss the implications for viral pathogenesis and therapeutic development of this remarkable convergence on specific membrane lipid blueprints for replication and transmission. Published by Elsevier Ltd.

  10. Intracellular Detection of Viral Transcription and Replication Using RNA FISH

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    2016-05-26

    Chapter 14. Intracellular detection of viral transcription and replication using RNA FISH i. Summary/Abstract Many hemorrhagic fever viruses...resolution. However, viral RNA tends to cluster in specific subcellular sites (e.g. viral replication factories). Thus while true single-molecule...assays [4]. Detection of viral RNA allows for in depth interrogation of the subcellular sites of viral replication and such experiments will help further

  11. Suppression of Poxvirus Replication by Resveratrol

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    Shuai Cao

    2017-11-01

    Full Text Available Poxviruses continue to cause serious diseases even after eradication of the historically deadly infectious human disease, smallpox. Poxviruses are currently being developed as vaccine vectors and cancer therapeutic agents. Resveratrol is a natural polyphenol stilbenoid found in plants that has been shown to inhibit or enhance replication of a number of viruses, but the effect of resveratrol on poxvirus replication is unknown. In the present study, we found that resveratrol dramatically suppressed the replication of vaccinia virus (VACV, the prototypic member of poxviruses, in various cell types. Resveratrol also significantly reduced the replication of monkeypox virus, a zoonotic virus that is endemic in Western and Central Africa and causes human mortality. The inhibitory effect of resveratrol on poxviruses is independent of VACV N1 protein, a potential resveratrol binding target. Further experiments demonstrated that resveratrol had little effect on VACV early gene expression, while it suppressed VACV DNA synthesis, and subsequently post-replicative gene expression.

  12. Grape Seed Proanthocyanidin Inhibits Mucin Synthesis and Viral Replication by Suppression of AP-1 and NF-κB via p38 MAPKs/JNK Signaling Pathways in Respiratory Syncytial Virus-Infected A549 Cells.

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    Lee, Jin-Woo; Kim, Young Il; Im, Chang-Nim; Kim, Sung Wan; Kim, Su Jin; Min, Seoyeon; Joo, Yong Hoon; Yim, Sung-Vin; Chung, Namhyun

    2017-06-07

    Airway epithelial cells are often infected by respiratory syncytial virus (RSV), one of the most common causes of asthma, bronchiolitis, chronic obstructive pulmonary disease, and pneumonia. During the infection process, excessive mucins instigate airway inflammation. However, the mechanism underlying RSV-induced airway hyper-responsiveness and inflammation is poorly understood. Furthermore, no reliable vaccines or drugs for antiviral therapy are available. In this study, the effect of the natural compound grape seed proanthocyanidin (GSP) on RSV-infected human airway epithelial cells A549 was evaluated. After pretreatment of the cells with or without exposure to RSV with 5-10 μg GSP/mL, the expression of various mucins (MUC1, MUC2, MUC5AC, MUC5B, and MUC8) was evaluated by real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blotting, as well as confocal microscopy. We found that GSP significantly decreased RSV-induced mucin synthesis at the mRNA and protein levels. In addition, GSP suppressed the RSV-induced signaling pathways, including extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38, together with nuclear factor kappa B (NF-κB) and activating protein-1 family members (c-Jun and c-Fos). Concomitantly, GSP inhibited the replication of RSV within A549 cells. Taken together, all our results suggest that GSP could be a potent therapeutic agent to suppress excessive mucus production and viral replication in RSV-induced airway inflammatory disorders.

  13. T-cell dysfunction in HIV-1-infected patients with impaired recovery of CD4 cells despite suppression of viral replication

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    Erikstrup, Christian; Kronborg, Gitte; Lohse, Nicolai

    2010-01-01

    INTRODUCTION: CD4 T-cell recovery is impeded in some HIVinfected patients despite successful combination antiretroviral therapy (cART) with suppressed HIV RNA. We hypothesized that T-cell dysfunction would be increased in these patients. METHODS: In the Danish HIV Cohort Study, we identified HIV-...

  14. Effects of interferon-α/β on HBV replication determined by viral load.

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    Yongjun Tian

    2011-07-01

    Full Text Available Interferons α and β (IFN-α/β are type I interferons produced by the host to control microbial infections. However, the use of IFN-α to treat hepatitis B virus (HBV patients generated sustained response to only a minority of patients. By using HBV transgenic mice as a model and by using hydrodynamic injection to introduce HBV DNA into the mouse liver, we studied the effect of IFN-α/β on HBV in vivo. Interestingly, our results indicated that IFN-α/β could have opposite effects on HBV: they suppressed HBV replication when viral load was high and enhanced HBV replication when viral load was low. IFN-α/β apparently suppressed HBV replication via transcriptional and post-transcriptional regulations. In contrast, IFN-α/β enhanced viral replication by inducing the transcription factor HNF3γ and activating STAT3, which together stimulated HBV gene expression and replication. Further studies revealed an important role of IFN-α/β in stimulating viral growth and prolonging viremia when viral load is low. This use of an innate immune response to enhance its replication and persistence may represent a novel strategy that HBV uses to enhance its growth and spread in the early stage of viral infection when the viral level is low.

  15. Effects of Interferon-α/β on HBV Replication Determined by Viral Load

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    Tian, Yongjun; Chen, Wen-ling; Ou, Jing-hsiung James

    2011-01-01

    Interferons α and β (IFN-α/β) are type I interferons produced by the host to control microbial infections. However, the use of IFN-α to treat hepatitis B virus (HBV) patients generated sustained response to only a minority of patients. By using HBV transgenic mice as a model and by using hydrodynamic injection to introduce HBV DNA into the mouse liver, we studied the effect of IFN-α/β on HBV in vivo. Interestingly, our results indicated that IFN-α/β could have opposite effects on HBV: they suppressed HBV replication when viral load was high and enhanced HBV replication when viral load was low. IFN-α/β apparently suppressed HBV replication via transcriptional and post-transcriptional regulations. In contrast, IFN-α/β enhanced viral replication by inducing the transcription factor HNF3γ and activating STAT3, which together stimulated HBV gene expression and replication. Further studies revealed an important role of IFN-α/β in stimulating viral growth and prolonging viremia when viral load is low. This use of an innate immune response to enhance its replication and persistence may represent a novel strategy that HBV uses to enhance its growth and spread in the early stage of viral infection when the viral level is low. PMID:21829354

  16. Viral trans-factor independent replication of human papillomavirus genomes

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    Angeletti Peter C

    2010-06-01

    Full Text Available Abstract Background Papillomaviruses (PVs establish a persistent infection in the proliferating basal cells of the epithelium. The viral genome is replicated and maintained as a low-copy nuclear plasmid in basal keratinocytes. Bovine and human papillomaviruses (BPV and HPV are known to utilize two viral proteins; E1, a DNA helicase, and E2, a transcription factor, which have been considered essential for viral DNA replication. However, growing evidence suggests that E1 and E2 are not entirely essential for stable replication of HPV. Results Here we report that multiple HPV16 mutants, lacking either or both E1 and E2 open reading frame (ORFs and the long control region (LCR, still support extrachromosomal replication. Our data clearly indicate that HPV16 has a mode of replication, independent of viral trans-factors, E1 and E2, which is achieved by origin activity located outside of the LCR.

  17. APOBEC3 Interference during Replication of Viral Genomes

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    Luc Willems

    2015-06-01

    Full Text Available Co-evolution of viruses and their hosts has reached a fragile and dynamic equilibrium that allows viral persistence, replication and transmission. In response, infected hosts have developed strategies of defense that counteract the deleterious effects of viral infections. In particular, single-strand DNA editing by Apolipoprotein B Editing Catalytic subunits proteins 3 (APOBEC3s is a well-conserved mechanism of mammalian innate immunity that mutates and inactivates viral genomes. In this review, we describe the mechanisms of APOBEC3 editing during viral replication, the viral strategies that prevent APOBEC3 activity and the consequences of APOBEC3 modulation on viral fitness and host genome integrity. Understanding the mechanisms involved reveals new prospects for therapeutic intervention.

  18. Suppression of viral infectivity through lethal defection

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    Grande-Pérez, Ana; Lázaro, Ester; Lowenstein, Pedro; Domingo, Esteban; Manrubia, Susanna C.

    2005-01-01

    RNA viruses replicate with a very high error rate and give rise to heterogeneous, highly plastic populations able to adapt very rapidly to changing environments. Viral diseases are thus difficult to control because of the appearance of drug-resistant mutants, and it becomes essential to seek mechanisms able to force the extinction of the quasispecies before adaptation emerges. An alternative to the use of conventional drugs consists in increasing the replication error rate through the use of mutagens. Here, we report about persistent infections of lymphocytic choriomeningitis virus treated with fluorouracil, where a progressive debilitation of infectivity leading to eventual extinction occurs. The transition to extinction is accompanied by the production of large amounts of RNA, indicating that the replicative ability of the quasispecies is not strongly impaired by the mutagen. By means of experimental and theoretical approaches, we propose that a fraction of the RNA molecules synthesized can behave as a defective subpopulation able to drive the viable class extinct. Our results lead to the identification of two extinction pathways, one at high amounts of mutagen, where the quasispecies completely loses its ability to infect and replicate, and a second one, at lower amounts of mutagen, where replication continues while the infective class gets extinct because of the action of defectors. The results bear on a potential application of increased mutagenesis as an antiviral strategy in that low doses of a mutagenic agent may suffice to drive persistent virus to extinction. PMID:15767582

  19. Human Parvovirus B19 Utilizes Cellular DNA Replication Machinery for Viral DNA Replication.

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    Zou, Wei; Wang, Zekun; Xiong, Min; Chen, Aaron Yun; Xu, Peng; Ganaie, Safder S; Badawi, Yomna; Kleiboeker, Steve; Nishimune, Hiroshi; Ye, Shui Qing; Qiu, Jianming

    2018-03-01

    Human parvovirus B19 (B19V) infection of human erythroid progenitor cells (EPCs) induces a DNA damage response and cell cycle arrest at late S phase, which facilitates viral DNA replication. However, it is not clear exactly which cellular factors are employed by this single-stranded DNA virus. Here, we used microarrays to systematically analyze the dynamic transcriptome of EPCs infected with B19V. We found that DNA metabolism, DNA replication, DNA repair, DNA damage response, cell cycle, and cell cycle arrest pathways were significantly regulated after B19V infection. Confocal microscopy analyses revealed that most cellular DNA replication proteins were recruited to the centers of viral DNA replication, but not the DNA repair DNA polymerases. Our results suggest that DNA replication polymerase δ and polymerase α are responsible for B19V DNA replication by knocking down its expression in EPCs. We further showed that although RPA32 is essential for B19V DNA replication and the phosphorylated forms of RPA32 colocalized with the replicating viral genomes, RPA32 phosphorylation was not necessary for B19V DNA replication. Thus, this report provides evidence that B19V uses the cellular DNA replication machinery for viral DNA replication. IMPORTANCE Human parvovirus B19 (B19V) infection can cause transient aplastic crisis, persistent viremia, and pure red cell aplasia. In fetuses, B19V infection can result in nonimmune hydrops fetalis and fetal death. These clinical manifestations of B19V infection are a direct outcome of the death of human erythroid progenitors that host B19V replication. B19V infection induces a DNA damage response that is important for cell cycle arrest at late S phase. Here, we analyzed dynamic changes in cellular gene expression and found that DNA metabolic processes are tightly regulated during B19V infection. Although genes involved in cellular DNA replication were downregulated overall, the cellular DNA replication machinery was tightly

  20. UGGT1 enhances enterovirus 71 pathogenicity by promoting viral RNA synthesis and viral replication.

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    Peng-Nien Huang

    2017-05-01

    Full Text Available Positive-strand RNA virus infections can induce the stress-related unfolded protein response (UPR in host cells. This study found that enterovirus A71 (EVA71 utilizes host UDP-glucose glycoprotein glucosyltransferase 1 (UGGT1, a key endoplasmic reticulum protein (ER involved in UPR, to enhance viral replication and virulence. EVA71 forms replication complexes (RCs on cellular membranes that contain a mix of host and viral proteins to facilitate viral replication, but the components and processes involved in the assembly and function of RCs are not fully understood. Using EVA71 as a model, this study found that host UGGT1 and viral 3D polymerase co-precipitate along with other factors on membranous replication complexes to enhance viral replication. Increased UGGT1 levels elevated viral growth rates, while viral pathogenicity was observed to be lower in heterozygous knockout mice (Uggt1 +/- mice. These findings provide important insight on the role of UPR and host UGGT1 in regulating RNA virus replication and pathogenicity.

  1. Bunyavirales ribonucleoproteins: the viral replication and transcription machinery.

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    Sun, Yeping; Li, Jing; Gao, George F; Tien, Po; Liu, Wenjun

    2018-03-08

    The Bunyavirales order is one of the largest groups of segmented negative-sense single-stranded RNA viruses, which includes many pathogenic strains that cause severe human diseases. The RNA segments of the bunyavirus genome are separately encapsidated by multiple copies of nucleoprotein (N), and both termini of each N-encapsidated genomic RNA segment bind to one copy of the viral L polymerase protein. The viral genomic RNA, N and L protein together form the ribonucleoprotein (RNP) complex that constitutes the molecular machinery for viral genome replication and transcription. Recently, breakthroughs have been achieved in understanding the architecture of bunyavirus RNPs with the determination of the atomic structures of the N and L proteins from various members of this order. In this review, we discuss the structures and functions of these bunyavirus RNP components, as well as viral genome replication and transcription mechanisms.

  2. Cyclophilins as Modulators of Viral Replication

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    Stephen D. Frausto

    2013-07-01

    Full Text Available Cyclophilins are peptidyl‐prolyl cis/trans isomerases important in the proper folding of certain proteins. Mounting evidence supports varied roles of cyclophilins, either positive or negative, in the life cycles of diverse viruses, but the nature and mechanisms of these roles are yet to be defined. The potential for cyclophilins to serve as a drug target for antiviral therapy is evidenced by the success of non-immunosuppressive cyclophilin inhibitors (CPIs, including Alisporivir, in clinical trials targeting hepatitis C virus infection. In addition, as cyclophilins are implicated in the predisposition to, or severity of, various diseases, the ability to specifically and effectively modulate their function will prove increasingly useful for disease intervention. In this review, we will summarize the evidence of cyclophilins as key mediators of viral infection and prospective drug targets.

  3. HSV-1 Remodels Host Telomeres to Facilitate Viral Replication

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    Zhong Deng

    2014-12-01

    Full Text Available Telomeres protect the ends of cellular chromosomes. We show here that infection with herpes simplex virus 1 (HSV-1 results in chromosomal structural aberrations at telomeres and the accumulation of telomere dysfunction-induced DNA damage foci (TIFs. At the molecular level, HSV-1 induces transcription of telomere repeat-containing RNA (TERRA, followed by the proteolytic degradation of the telomere protein TPP1 and loss of the telomere repeat DNA signal. The HSV-1-encoded E3 ubiquitin ligase ICP0 is required for TERRA transcription and facilitates TPP1 degradation. Small hairpin RNA (shRNA depletion of TPP1 increases viral replication, indicating that TPP1 inhibits viral replication. Viral replication protein ICP8 forms foci that coincide with telomeric proteins, and ICP8-null virus failed to degrade telomere DNA signal. These findings suggest that HSV-1 reorganizes telomeres to form ICP8-associated prereplication foci and to promote viral genomic replication.

  4. Clade-specific differences in active viral replication and compartmentalization

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    Sala, Monica; Centlivre, Mireille; Wain-Hobson, Simon

    2006-01-01

    This review focuses on the impact of HIV-1 clade-specific polymorphisms on the dynamics of viral replication and compartmentalization in vivo. HIV-1 transcription and compartmentalization are essentially modulated by interconnected parameters: cellular activation by T-cell receptor engagement or

  5. HIV Exploits Antiviral Host Innate GCN2-ATF4 Signaling for Establishing Viral Replication Early in Infection.

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    Jiang, Guochun; Santos Rocha, Clarissa; Hirao, Lauren A; Mendes, Erica A; Tang, Yuyang; Thompson, George R; Wong, Joseph K; Dandekar, Satya

    2017-05-02

    Antiviral innate host defenses against acute viral infections include suppression of host protein synthesis to restrict viral protein production. Less is known about mechanisms by which viral pathogens subvert host antiviral innate responses for establishing their replication and dissemination. We investigated early innate defense against human immunodeficiency virus (HIV) infection and viral evasion by utilizing human CD4 + T cell cultures in vitro and a simian immunodeficiency virus (SIV) model of AIDS in vivo Our data showed that early host innate defense against the viral infection involves GCN2-ATF4 signaling-mediated suppression of global protein synthesis, which is exploited by the virus for supporting its own replication during early viral infection and dissemination in the gut mucosa. Suppression of protein synthesis and induction of protein kinase GCN2-ATF4 signaling were detected in the gut during acute SIV infection. These changes diminished during chronic viral infection. HIV replication induced by serum deprivation in CD4 + T cells was linked to the induction of ATF4 that was recruited to the HIV long terminal repeat (LTR) to promote viral transcription. Experimental inhibition of GCN2-ATF4 signaling either by a specific inhibitor or by amino acid supplementation suppressed the induction of HIV expression. Enhancing ATF4 expression through selenium administration resulted in reactivation of latent HIV in vitro as well as ex vivo in the primary CD4 + T cells isolated from patients receiving suppressive antiretroviral therapy (ART). In summary, HIV/SIV exploits the early host antiviral response through GCN2-ATF4 signaling by utilizing ATF4 for activating the viral LTR transcription to establish initial viral replication and is a potential target for HIV prevention and therapy. IMPORTANCE Understanding how HIV overcomes host antiviral innate defense response in order to establish infection and dissemination is critical for developing prevention and

  6. HIV Exploits Antiviral Host Innate GCN2-ATF4 Signaling for Establishing Viral Replication Early in Infection

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    Guochun Jiang

    2017-05-01

    Full Text Available Antiviral innate host defenses against acute viral infections include suppression of host protein synthesis to restrict viral protein production. Less is known about mechanisms by which viral pathogens subvert host antiviral innate responses for establishing their replication and dissemination. We investigated early innate defense against human immunodeficiency virus (HIV infection and viral evasion by utilizing human CD4+ T cell cultures in vitro and a simian immunodeficiency virus (SIV model of AIDS in vivo. Our data showed that early host innate defense against the viral infection involves GCN2-ATF4 signaling-mediated suppression of global protein synthesis, which is exploited by the virus for supporting its own replication during early viral infection and dissemination in the gut mucosa. Suppression of protein synthesis and induction of protein kinase GCN2-ATF4 signaling were detected in the gut during acute SIV infection. These changes diminished during chronic viral infection. HIV replication induced by serum deprivation in CD4+ T cells was linked to the induction of ATF4 that was recruited to the HIV long terminal repeat (LTR to promote viral transcription. Experimental inhibition of GCN2-ATF4 signaling either by a specific inhibitor or by amino acid supplementation suppressed the induction of HIV expression. Enhancing ATF4 expression through selenium administration resulted in reactivation of latent HIV in vitro as well as ex vivo in the primary CD4+ T cells isolated from patients receiving suppressive antiretroviral therapy (ART. In summary, HIV/SIV exploits the early host antiviral response through GCN2-ATF4 signaling by utilizing ATF4 for activating the viral LTR transcription to establish initial viral replication and is a potential target for HIV prevention and therapy.

  7. Bacteriophage SPP1 DNA replication strategies promote viral and disable host replication in vitro.

    Science.gov (United States)

    Seco, Elena M; Zinder, John C; Manhart, Carol M; Lo Piano, Ambra; McHenry, Charles S; Ayora, Silvia

    2013-02-01

    Complex viruses that encode their own initiation proteins and subvert the host's elongation apparatus have provided valuable insights into DNA replication. Using purified bacteriophage SPP1 and Bacillus subtilis proteins, we have reconstituted a rolling circle replication system that recapitulates genetically defined protein requirements. Eleven proteins are required: phage-encoded helicase (G40P), helicase loader (G39P), origin binding protein (G38P) and G36P single-stranded DNA-binding protein (SSB); and host-encoded PolC and DnaE polymerases, processivity factor (β(2)), clamp loader (τ-δ-δ') and primase (DnaG). This study revealed a new role for the SPP1 origin binding protein. In the presence of SSB, it is required for initiation on replication forks that lack origin sequences, mimicking the activity of the PriA replication restart protein in bacteria. The SPP1 replisome is supported by both host and viral SSBs, but phage SSB is unable to support B. subtilis replication, likely owing to its inability to stimulate the PolC holoenzyme in the B. subtilis context. Moreover, phage SSB inhibits host replication, defining a new mechanism by which bacterial replication could be regulated by a viral factor.

  8. Recruitment of Brd4 to the human papillomavirus type 16 DNA replication complex is essential for replication of viral DNA.

    Science.gov (United States)

    Wang, Xin; Helfer, Christine M; Pancholi, Neha; Bradner, James E; You, Jianxin

    2013-04-01

    Replication of the human papillomavirus (HPV) DNA genome relies on viral factors E1 and E2 and the cellular replication machinery. Bromodomain-containing protein 4 (Brd4) interacts with viral E2 protein to mediate papillomavirus (PV) genome maintenance and viral transcription. However, the functional role of Brd4 in the HPV life cycle remains to be clearly defined. In this study, we provide the first look into the E2-Brd4 interaction in the presence of other important viral factors, such as the HPV16 E1 protein and the viral genome. We show that Brd4 is recruited to actively replicating HPV16 origin foci together with HPV16 E1, E2, and a number of the cellular replication factors: replication protein A70 (RPA70), replication factor C1 (RFC1), and DNA polymerase δ. Mutagenesis disrupting the E2-Brd4 interaction abolishes the formation of the HPV16 replication complex and impairs HPV16 DNA replication in cells. Brd4 was further demonstrated to be necessary for HPV16 viral DNA replication using a cell-free replication system in which depletion of Brd4 by small interfering RNA (siRNA) silencing leads to impaired HPV16 viral DNA replication and recombinant Brd4 protein is able to rescue viral DNA replication. In addition, releasing endogenous Brd4 from cellular chromatin by using the bromodomain inhibitor JQ1(+) enhances HPV16 DNA replication, demonstrating that the role of Brd4 in HPV DNA replication could be uncoupled from its function in chromatin-associated transcriptional regulation and cell cycle control. Our study reveals a new role for Brd4 in HPV genome replication, providing novel insights into understanding the life cycle of this oncogenic DNA virus.

  9. The N-Terminal of Aquareovirus NS80 Is Required for Interacting with Viral Proteins and Viral Replication.

    Directory of Open Access Journals (Sweden)

    Jie Zhang

    Full Text Available Reovirus replication and assembly occurs within viral inclusion bodies that formed in specific intracellular compartments of cytoplasm in infected cells. Previous study indicated that aquareovirus NS80 is able to form inclusion bodies, and also can retain viral proteins within its inclusions. To better understand how NS80 performed in viral replication and assembly, the functional regions of NS80 associated with other viral proteins in aquareovirus replication were investigated in this study. Deletion mutational analysis and rotavirus NSP5-based protein association platform were used to detect association regions. Immunofluorescence images indicated that different N-terminal regions of NS80 could associate with viral proteins VP1, VP4, VP6 and NS38. Further co-immunoprecipitation analysis confirmed the interaction between VP1, VP4, VP6 or NS38 with different regions covering the N-terminal amino acid (aa, 1-471 of NS80, respectively. Moreover, removal of NS80 N-terminal sequences required for interaction with proteins VP1, VP4, VP6 or NS38 not only prevented the capacity of NS80 to support viral replication in NS80 shRNA-based replication complementation assays, but also inhibited the expression of aquareovirus proteins, suggesting that N-terminal regions of NS80 are necessary for viral replication. These results provided a foundational basis for further understanding the role of NS80 in viral replication and assembly during aquareovirus infection.

  10. Recruitment of Brd4 to the Human Papillomavirus Type 16 DNA Replication Complex Is Essential for Replication of Viral DNA

    OpenAIRE

    Wang, Xin; Helfer, Christine M.; Pancholi, Neha; Bradner, James E.; You, Jianxin

    2013-01-01

    Replication of the human papillomavirus (HPV) DNA genome relies on viral factors E1 and E2 and the cellular replication machinery. Bromodomain-containing protein 4 (Brd4) interacts with viral E2 protein to mediate papillomavirus (PV) genome maintenance and viral transcription. However, the functional role of Brd4 in the HPV life cycle remains to be clearly defined. In this study, we provide the first look into the E2-Brd4 interaction in the presence of other important viral factors, such as t...

  11. Dynamics of viral replication in blood and lymphoid tissues during SIVmac251 infection of macaques

    Directory of Open Access Journals (Sweden)

    Mannioui Abdelkrim

    2009-01-01

    Full Text Available Abstract Background Extensive studies of primary infection are crucial to our understanding of the course of HIV disease. In SIV-infected macaques, a model closely mimicking HIV pathogenesis, we used a combination of three markers -- viral RNA, 2LTR circles and viral DNA -- to evaluate viral replication and dissemination simultaneously in blood, secondary lymphoid tissues, and the gut during primary and chronic infections. Subsequent viral compartmentalization in the main target cells of the virus in peripheral blood during the chronic phase of infection was evaluated by cell sorting and viral quantification with the three markers studied. Results The evolutions of viral RNA, 2LTR circles and DNA levels were correlated in a given tissue during primary and early chronic infection. The decrease in plasma viral load principally reflects a large decrease in viral replication in gut-associated lymphoid tissue (GALT, with viral RNA and DNA levels remaining stable in the spleen and peripheral lymph nodes. Later, during chronic infection, a progressive depletion of central memory CD4+ T cells from the peripheral blood was observed, accompanied by high levels of viral replication in the cells of this subtype. The virus was also found to replicate at this point in the infection in naive CD4+ T cells. Viral RNA was frequently detected in monocytes, but no SIV replication appeared to occur in these cells, as no viral DNA or 2LTR circles were detected. Conclusion We demonstrated the persistence of viral replication and dissemination, mostly in secondary lymphoid tissues, during primary and early chronic infection. During chronic infection, the central memory CD4+ T cells were the major site of viral replication in peripheral blood, but viral replication also occurred in naive CD4+ T cells. The role of monocytes seemed to be limited to carrying the virus as a cargo because there was an observed lack of replication in these cells. These data may have important

  12. Replication-Coupled Recruitment of Viral and Cellular Factors to Herpes Simplex Virus Type 1 Replication Forks for the Maintenance and Expression of Viral Genomes

    Science.gov (United States)

    Dembowski, Jill A.

    2017-01-01

    Herpes simplex virus type 1 (HSV-1) infects over half the human population. Much of the infectious cycle occurs in the nucleus of cells where the virus has evolved mechanisms to manipulate host processes for the production of virus. The genome of HSV-1 is coordinately expressed, maintained, and replicated such that progeny virions are produced within 4–6 hours post infection. In this study, we selectively purify HSV-1 replication forks and associated proteins from virus-infected cells and identify select viral and cellular replication, repair, and transcription factors that associate with viral replication forks. Pulse chase analyses and imaging studies reveal temporal and spatial dynamics between viral replication forks and associated proteins and demonstrate that several DNA repair complexes and key transcription factors are recruited to or near replication forks. Consistent with these observations we show that the initiation of viral DNA replication is sufficient to license late gene transcription. These data provide insight into mechanisms that couple HSV-1 DNA replication with transcription and repair for the coordinated expression and maintenance of the viral genome. PMID:28095497

  13. Host heterogeneous ribonucleoprotein K (hnRNP K as a potential target to suppress hepatitis B virus replication.

    Directory of Open Access Journals (Sweden)

    2005-07-01

    Full Text Available BACKGROUND: Hepatitis B virus (HBV infection results in complications such as cirrhosis and hepatocellular carcinoma. Suppressing viral replication in chronic HBV carriers is an effective approach to controlling disease progression. Although antiviral compounds are available, we aimed to identify host factors that have a significant effect on viral replication efficiency. METHODS AND FINDINGS: We studied a group of hepatitis B carriers by associating serum viral load with their respective HBV genomes, and observed a significant association between high patient serum viral load with a natural sequence variant within the HBV enhancer II (Enh II regulatory region at position 1752. Using a viral fragment as an affinity binding probe, we isolated a host DNA-binding protein belonging to the class of heterogeneous nuclear ribonucleoproteins--hnRNP K--that binds to and modulates the replicative efficiency of HBV. In cell transfection studies, overexpression of hnRNP K augmented HBV replication, while gene silencing of endogenous hnRNP K carried out by small interfering RNAs resulted in a significant reduction of HBV viral load. CONCLUSION: The evidence presented in this study describes a wider role for hnRNP K beyond maintenance of host cellular functions and may represent a novel target for pharmacologic intervention of HBV replication.

  14. Heat Shock Protein 90 Ensures Efficient Mumps Virus Replication by Assisting with Viral Polymerase Complex Formation.

    Science.gov (United States)

    Katoh, Hiroshi; Kubota, Toru; Nakatsu, Yuichiro; Tahara, Maino; Kidokoro, Minoru; Takeda, Makoto

    2017-03-15

    Paramyxoviral RNAs are synthesized by a viral RNA-dependent RNA polymerase (RdRp) consisting of the large (L) protein and its cofactor phosphoprotein (P protein). The L protein is a multifunctional protein that catalyzes RNA synthesis, mRNA capping, and mRNA polyadenylation. Growing evidence shows that the stability of several paramyxovirus L proteins is regulated by heat shock protein 90 (Hsp90). In this study, we demonstrated that Hsp90 activity was important for mumps virus (MuV) replication. The Hsp90 activity was required for L-protein stability and activity because an Hsp90-specific inhibitor, 17-allylamino-17-demethoxygeldanamycin (17-AAG), destabilized the MuV L protein and suppressed viral RNA synthesis. However, once the L protein formed a mature polymerase complex with the P protein, Hsp90 activity was no longer required for the stability and activity of the L protein. When the Hsp90 activity was inhibited, the MuV L protein was degraded through the CHIP (C terminus of Hsp70-interacting protein)-mediated proteasomal pathway. High concentrations of 17-AAG showed strong cytotoxicity to certain cell types, but combined use of an Hsp70 inhibitor, VER155008, potentiated degradation of the L protein, allowing a sufficient reduction of 17-AAG concentration to block MuV replication with minimum cytotoxicity. Regulation of the L protein by Hsp90 and Hsp70 chaperones was also demonstrated for another paramyxovirus, the measles virus. Collectively, our data show that the Hsp90/Hsp70 chaperone machinery assists in the maturation of the paramyxovirus L protein and thereby in the formation of a mature RdRp complex and efficient viral replication. IMPORTANCE Heat shock protein 90 (Hsp90) is nearly universally required for viral protein homeostasis. Here, we report that Hsp90 activity is required for efficient propagation of mumps virus (MuV). Hsp90 functions in the maintenance of the catalytic subunit of viral polymerase, the large (L) protein, prior to formation of a

  15. Viral rewiring of cellular lipid metabolism to create membranous replication compartments

    NARCIS (Netherlands)

    Strating, Jeroen Rpm; van Kuppeveld, Frank Jm

    2017-01-01

    Positive-strand RNA (+RNA) viruses (e.g. poliovirus, hepatitis C virus, dengue virus, SARS-coronavirus) remodel cellular membranes to form so-called viral replication compartments (VRCs), which are the sites where viral RNA genome replication takes place. To induce VRC formation, these viruses

  16. Kinetics of viral replication and local and systemic immune responses in experimental rotavirus infection.

    OpenAIRE

    Eydelloth, R S; Vonderfecht, S L; Sheridan, J F; Enders, L D; Yolken, R H

    1984-01-01

    Rotavirus-seronegative mice were orally inoculated with murine rotavirus in order to study the kinetics of rotavirus replication and the relationship of viral replication to immunity and disease and to assess the effects of local and systemic antibodies on viral clearance and disease resolution.

  17. Kinetics of viral replication and local and systemic immune responses in experimental rotavirus infection.

    Science.gov (United States)

    Eydelloth, R S; Vonderfecht, S L; Sheridan, J F; Enders, L D; Yolken, R H

    1984-06-01

    Rotavirus-seronegative mice were orally inoculated with murine rotavirus in order to study the kinetics of rotavirus replication and the relationship of viral replication to immunity and disease and to assess the effects of local and systemic antibodies on viral clearance and disease resolution.

  18. Differential Requirement of Human Cytomegalovirus UL112-113 Protein Isoforms for Viral Replication.

    Science.gov (United States)

    Schommartz, Tim; Tang, Jiajia; Brost, Rebekka; Brune, Wolfram

    2017-09-01

    The UL112-113 gene is one of the few alternatively spliced genes of human cytomegalovirus (HCMV). It codes for four phosphoproteins, p34, p43, p50, and p84, all of which are expressed with early kinetics and accumulate at sites of viral DNA replication within the host cell nucleus. Although these proteins are known to play important, possibly essential, roles in the viral replication cycle, little is known about the contribution of individual UL112-113 protein products. Here we used splice site mutagenesis, intron deletion and substitution, and nonsense mutagenesis to prevent the individual expression of each UL112-113 protein isoform and to investigate the importance of each isoform for viral replication. We show that HCMV mutants lacking p34 or p50 expression replicated to high titers in human fibroblasts and endothelial cells, indicating that these proteins are nonessential for viral replication, while mutant viruses carrying a stop mutation within the p84 coding sequence were severely growth impaired. Viral replication could not be detected upon the inactivation of p43 expression, indicating that this UL112-113 protein is essential for viral replication. We also analyzed the ability of UL112-113 proteins to recruit other viral proteins to intranuclear prereplication compartments. While UL112-113 expression was sufficient to recruit the UL44-encoded viral DNA polymerase processivity factor, it was not sufficient for the recruitment of the viral UL84 and UL117 proteins. Remarkably, both the p43 and p84 isoforms were required for the efficient recruitment of pUL44, which is consistent with their critical role in the viral life cycle. IMPORTANCE Human cytomegalovirus requires gene products from 11 genetic loci for the lytic replication of its genome. One of these loci, UL112-113, encodes four proteins with common N termini by alternative splicing. In this study, we inactivated the expression of each of the four UL112-113 proteins individually and determined their

  19. HIV-1 clade promoters strongly influence spatial and temporal dynamics of viral replication in vivo

    NARCIS (Netherlands)

    Centlivre, Mireille; Sommer, Peter; Michel, Marie; Ho Tsong Fang, Raphaël; Gofflo, Sandrine; Valladeau, Jenny; Schmitt, Nathalie; Thierry, Françoise; Hurtrel, Bruno; Wain-Hobson, Simon; Sala, Monica

    2005-01-01

    Although the primary determinant of cell tropism is the interaction of viral envelope or capsid proteins with cellular receptors, other viral elements can strongly modulate viral replication. While the HIV-1 promoter is polymorphic for a variety of transcription factor binding sites, the impact of

  20. Plum Pox Virus 6K1 Protein Is Required for Viral Replication and Targets the Viral Replication Complex at the Early Stage of Infection.

    Science.gov (United States)

    Cui, Hongguang; Wang, Aiming

    2016-05-15

    The potyviral RNA genome encodes two polyproteins that are proteolytically processed by three viral protease domains into 11 mature proteins. Extensive molecular studies have identified functions for the majority of the viral proteins. For example, 6K2, one of the two smallest potyviral proteins, is an integral membrane protein and induces the endoplasmic reticulum (ER)-originated replication vesicles that target the chloroplast for robust viral replication. However, the functional role of 6K1, the other smallest protein, remains uncharacterized. In this study, we developed a series of recombinant full-length viral cDNA clones derived from a Canadian Plum pox virus (PPV) isolate. We found that deletion of any of the short motifs of 6K1 (each of which ranged from 5 to 13 amino acids), most of the 6K1 sequence (but with the conserved sequence of the cleavage sites being retained), or all of the 6K1 sequence in the PPV infectious clone abolished viral replication. The trans expression of 6K1 or the cis expression of a dislocated 6K1 failed to rescue the loss-of-replication phenotype, suggesting the temporal and spatial requirement of 6K1 for viral replication. Disruption of the N- or C-terminal cleavage site of 6K1, which prevented the release of 6K1 from the polyprotein, either partially or completely inhibited viral replication, suggesting the functional importance of the mature 6K1. We further found that green fluorescent protein-tagged 6K1 formed punctate inclusions at the viral early infection stage and colocalized with chloroplast-bound viral replicase elements 6K2 and NIb. Taken together, our results suggest that 6K1 is required for viral replication and is an important viral element of the viral replication complex at the early infection stage. Potyviruses account for more than 30% of known plant viruses and consist of many agriculturally important viruses. The genomes of potyviruses encode two polyproteins that are proteolytically processed into 11 mature

  1. The human cytomegalovirus gene products essential for late viral gene expression assemble into prereplication complexes before viral DNA replication.

    Science.gov (United States)

    Isomura, Hiroki; Stinski, Mark F; Murata, Takayuki; Yamashita, Yoriko; Kanda, Teru; Toyokuni, Shinya; Tsurumi, Tatsuya

    2011-07-01

    The regulation of human cytomegalovirus (HCMV) late gene expression by viral proteins is poorly understood, and these viral proteins could be targets for novel antivirals. HCMV open reading frames (ORFs) UL79, -87, and -95 encode proteins with homology to late gene transcription factors of murine gammaherpesvirus 68 ORFs 18, 24, and 34, respectively. To determine whether these HCMV proteins are also essential for late gene transcription of a betaherpesvirus, we mutated HCMV ORFs UL79, -87, and -95. Cells were infected with the recombinant viruses at high and low multiplicities of infection (MOIs). While viral DNA was detected with the recombinant viruses, infectious virus was not detected unless the wild-type viral proteins were expressed in trans. At a high MOI, mutation of ORF UL79, -87, or -95 had no effect on the level of major immediate-early (MIE) gene expression or viral DNA replication, but late viral gene expression from the UL44, -75, and -99 ORFs was not detected. At a low MOI, preexpression of UL79 or -87, but not UL95, in human fibroblast cells negatively affected the level of MIE viral gene expression and viral DNA replication. The products of ORFs UL79, -87, and -95 were expressed as early viral proteins and recruited to prereplication complexes (pre-RCs), along with UL44, before the initiation of viral DNA replication. All three HCMV ORFs are indispensable for late viral gene expression and viral growth. The roles of UL79, -87, and -95 in pre-RCs for late viral gene expression are discussed.

  2. Proteasome inhibitors induce apoptosis and reduce viral replication in primary effusion lymphoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Saji, Chiaki [Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060-0812 (Japan); Higashi, Chizuka; Niinaka, Yasufumi [Faculty of Medicine, University of Yamanashi, Chuoh-shi 409-3898 (Japan); Yamada, Koji [Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060-0812 (Japan); Noguchi, Kohji [Faculty of Pharmacy, Keio University, 1-5-30 Shiba-koen, Minato-ku, Tokyo 105-8512 (Japan); Fujimuro, Masahiro, E-mail: fuji2@mb.kyoto-phu.ac.jp [Department of Cell Biology, Kyoto Pharmaceutical University, Misasagi-Shichonocho 1, Yamashinaku, Kyoto 607-8412 (Japan)

    2011-12-02

    Highlights: Black-Right-Pointing-Pointer Constitutive NF-{kappa}B signaling is essential for the survival and growth of PEL cells. Black-Right-Pointing-Pointer NF-{kappa}B signaling is upregulated by the proteasome-dependent degradation of I{kappa}B{alpha}. Black-Right-Pointing-Pointer Proteasome inhibitors suppress NF-{kappa}B signaling and induce apoptosis in PEL cells through stabilization of I{kappa}B{alpha}. Black-Right-Pointing-Pointer Proteasome inhibitors suppress viral replication in PEL cells during lytic KSHV infection. -- Abstract: Primary effusion lymphoma (PEL) is an aggressive neoplasm caused by Kaposi's sarcoma-associated herpesvirus (KSHV). This study provides evidence that proteasomal activity is required for both survival of PEL cells stably harboring the KSHV genome and viral replication of KSHV. We evaluated the cytotoxic effects of proteasome inhibitors on PEL cells. The proteasome inhibitors MG132, lactacystin, and proteasome inhibitor I dramatically inhibited cell proliferation and induced apoptosis of PEL cells through the accumulation of p21 and p27. Furthermore, proteasome inhibitors induced the stabilization of NF-{kappa}B inhibitory molecule (I{kappa}B{alpha}) and suppressed the transcriptional activity of NF-{kappa}B in PEL cells. The NF-{kappa}B specific inhibitor BAY11-7082 also induced apoptosis in PEL cells. The constitutive activation of NF-{kappa}B signaling is essential for the survival and growth of B cell lymphoma cells, including PEL cells. NF-{kappa}B signaling is upregulated by proteasome-dependent degradation of I{kappa}B{alpha}. The suppression of NF-{kappa}B signaling by proteasome inhibitors may contribute to the induction of apoptosis in PEL cells. In addition, proteasome activity is required for KSHV replication in KSHV latently infected PEL cells. MG132 reduced the production of progeny virus from PEL cells at low concentrations, which do not affect PEL cell growth. These findings suggest that proteasome

  3. HIV Care Saves Lives: Viral Suppression is Key PSA (:60)

    Centers for Disease Control (CDC) Podcasts

    2014-11-25

    This 60 second Public Service Announcement is based on the December 2014 Vital Signs. For people living with HIV, Viral suppression is critical. By getting tested and taking HIV medicines, individuals living with HIV can achieve very low levels of HIV in the body.  Created: 11/25/2014 by National Center for Injury Prevention and Control (NCIPC).   Date Released: 11/25/2014.

  4. A dimeric Rep protein initiates replication of a linear archaeal virus genome: implications for the Rep mechanism and viral replication

    DEFF Research Database (Denmark)

    Oke, Muse; Kerou, Melina; Liu, Huanting

    2011-01-01

    that a protein encoded in the 34-kbp genome of the rudivirus SIRV1 is a member of the replication initiator (Rep) superfamily of proteins, which initiate rolling-circle replication (RCR) of diverse viruses and plasmids. We show that SIRV Rep nicks the viral hairpin terminus, forming a covalent adduct between...... positioned active sites, each with a single tyrosine residue, work in tandem to catalyze DNA nicking and joining. We propose a novel mechanism for rudivirus DNA replication, incorporating the first known example of a Rep protein that is not linked to RCR. The implications for Rep protein function and viral......The Rudiviridae are a family of rod-shaped archaeal viruses with covalently closed, linear double-stranded DNA (dsDNA) genomes. Their replication mechanisms remain obscure, although parallels have been drawn to the Poxviridae and other large cytoplasmic eukaryotic viruses. Here we report...

  5. Nidovirus replication structures : hijacking membranes to support viral RNA synthesis

    NARCIS (Netherlands)

    Knoops, Kèvin

    2011-01-01

    Positive-stranded RNA viruses replicate in the cytoplasm of host cells and their replication complexes are associated with modified cell membranes. We investigated the structure of the nidovirus-induced membrane modifications and found that nidoviruses transform the endoplasmic reticulum into a

  6. Suppression of HBV replication by the expression of nickase- and nuclease dead-Cas9.

    Science.gov (United States)

    Kurihara, Takeshi; Fukuhara, Takasuke; Ono, Chikako; Yamamoto, Satomi; Uemura, Kentaro; Okamoto, Toru; Sugiyama, Masaya; Motooka, Daisuke; Nakamura, Shota; Ikawa, Masato; Mizokami, Masashi; Maehara, Yoshihiko; Matsuura, Yoshiharu

    2017-07-21

    Complete removal of hepatitis B virus (HBV) DNA from nuclei is difficult by the current therapies. Recent reports have shown that a novel genome-editing tool using Cas9 with a single-guide RNA (sgRNA) system can cleave the HBV genome in vitro and in vivo. However, induction of a double-strand break (DSB) on the targeted genome by Cas9 risks undesirable off-target cleavage on the host genome. Nickase-Cas9 cleaves a single strand of DNA, and thereby two sgRNAs are required for inducing DSBs. To avoid Cas9-induced off-target mutagenesis, we examined the effects of the expressions of nickase-Cas9 and nuclease dead Cas9 (d-Cas9) with sgRNAs on HBV replication. The expression of nickase-Cas9 with a pair of sgRNAs cleaved the target HBV genome and suppressed the viral-protein expression and HBV replication in vitro. Moreover, nickase-Cas9 with the sgRNA pair cleaved the targeted HBV genome in mouse liver. Interestingly, d-Cas9 expression with the sgRNAs also suppressed HBV replication in vitro without cleaving the HBV genome. These results suggest the possible use of nickase-Cas9 and d-Cas9 with a pair of sgRNAs for eliminating HBV DNA from the livers of chronic hepatitis B patients with low risk of undesirable off-target mutation on the host genome.

  7. The actin-like MreB cytoskeleton organizes viral DNA replication in bacteria.

    Science.gov (United States)

    Muñoz-Espín, Daniel; Daniel, Richard; Kawai, Yoshikazu; Carballido-López, Rut; Castilla-Llorente, Virginia; Errington, Jeff; Meijer, Wilfried J J; Salas, Margarita

    2009-08-11

    Little is known about the organization or proteins involved in membrane-associated replication of prokaryotic genomes. Here we show that the actin-like MreB cytoskeleton of the distantly related bacteria Escherichia coli and Bacillus subtilis is required for efficient viral DNA replication. Detailed analyses of B. subtilis phage ϕ29 showed that the MreB cytoskeleton plays a crucial role in organizing phage DNA replication at the membrane. Thus, phage double-stranded DNA and components of the ϕ29 replication machinery localize in peripheral helix-like structures in a cytoskeleton-dependent way. Importantly, we show that MreB interacts directly with the ϕ29 membrane-protein p16.7, responsible for attaching viral DNA at the cell membrane. Altogether, the results reveal another function for the MreB cytoskeleton and describe a mechanism by which viral DNA replication is organized at the bacterial membrane.

  8. In vitro anti-reovirus activity of kuraridin isolated from Sophora flavescens against viral replication and hemagglutination

    Directory of Open Access Journals (Sweden)

    Hyung-Jun Kwon

    2015-08-01

    Full Text Available In this study, we evaluated the anti-reovirus activity of kuraridin isolated from the roots of Sophora flavescens. In particular, we focused on whether this property is attributable to direct inhibition of reovirus attachment and/or inhibition of viral replication with the aid of time-of-addition (pre-treatment, simultaneous treatment, and post-treatment experiments. No significant antiviral activity of kuraridin was detected in the pre-treatment assay. In the simultaneous assay, the 50% effective inhibitory concentrations (EC50 of kuraridin were 15.3–176.9 μM against human type 1–3 reoviruses (HRV1–3 and Korean porcine reovirus (PRV. Kuraridin completely blocked binding of viral sigma 1 protein to sialic acids at concentrations lower than 82.5 μM in the hemagglutination inhibition assay. Moreover, kuraridin inhibited HRV1–3 and PRV viral replication with EC50 values of 14.0–62.0 μM. Quantitative real-time PCR analysis disclosed strong suppression of reovirus RNA synthesis at the late stage (18 h of virus replication by kuraridin. The viral yields of kuraridin-treated cells were significantly reduced at 24 h post-infection, compared with DMSO-treated cells. Our results collectively suggest that kuraridin inhibits virus adsorption and replication by inhibiting hemagglutination, viral RNA and protein synthesis and virus shedding, supporting its utility as a viable candidate antiviral drug against reoviruses.

  9. Viral and Cellular Components of AAV2 Replication Compartments

    Science.gov (United States)

    Vogel, Rebecca; Seyffert, Michael; Pereira, Bruna de Andrade; Fraefel, Cornel

    2013-01-01

    Adeno-associated virus 2 (AAV2) is a helpervirus-dependent parvovirus with a bi-phasic life cycle comprising latency in absence and lytic replication in presence of a helpervirus, such as adenovirus (Ad) or herpes simplex virus type 1 (HSV-1). Helpervirus-supported AAV2 replication takes place in replication compartments (RCs) in the cell nucleus where virus DNA replication and transcription occur. RCs consist of a defined set of helper virus-, AAV2-, and cellular proteins. Here we compare the profile of cellular proteins recruited into AAV2 RCs or identified in Rep78-associated complexes when either Ad or HSV-1 is the helpervirus, and we discuss the potential roles of some of these proteins in AAV2 and helpervirus infection. PMID:24222808

  10. Brd4 Is Displaced from HPV Replication Factories as They Expand and Amplify Viral DNA

    Science.gov (United States)

    Sakakibara, Nozomi; Chen, Dan; Jang, Moon Kyoo; Kang, Dong Wook; Luecke, Hans F.; Wu, Shwu-Yuan; Chiang, Cheng-Ming; McBride, Alison A.

    2013-01-01

    Replication foci are generated by many viruses to concentrate and localize viral DNA synthesis to specific regions of the cell. Expression of the HPV16 E1 and E2 replication proteins in keratinocytes results in nuclear foci that recruit proteins associated with the host DNA damage response. We show that the Brd4 protein localizes to these foci and is essential for their formation. However, when E1 and E2 begin amplifying viral DNA, Brd4 is displaced from the foci and cellular factors associated with DNA synthesis and homologous recombination are recruited. Differentiated HPV-infected keratinocytes form similar nuclear foci that contain amplifying viral DNA. We compare the different foci and show that, while they have many characteristics in common, there is a switch between early Brd4-dependent foci and mature Brd4-independent replication foci. However, HPV genomes encoding mutated E2 proteins that are unable to bind Brd4 can replicate and amplify the viral genome. We propose that, while E1, E2 and Brd4 might bind host chromatin at early stages of infection, there is a temporal and functional switch at later stages and increased E1 and E2 levels promote viral DNA amplification, displacement of Brd4 and growth of a replication factory. The concomitant DNA damage response recruits proteins required for DNA synthesis and repair, which could then be utilized for viral DNA replication. Hence, while Brd4 can enhance replication by concentrating viral processes in specific regions of the host nucleus, this interaction is not absolutely essential for HPV replication. PMID:24278023

  11. Pterodontic Acid Isolated from Laggera pterodonta Inhibits Viral Replication and Inflammation Induced by Influenza A Virus

    Directory of Open Access Journals (Sweden)

    Wenda Guan

    2017-10-01

    Full Text Available Laggera pterodonta (DC. Benth. is a traditional Chinese medicine. The previous study revealed that the crude extracts of this herb could inhibit influenza virus infection, but its anti-influenza components and underlying mechanism of action remain unknown. Column chromatography was performed to isolate components from the plant. Activity against influenza virus of the compound was determined by CPE inhibition assay. Neuraminidase (NA inhibition was measured by chemiluminescence assay. The anti-virus and anti-inflammation effects were determined using dual-luciferase reporter assay, immunofluorescence, quantitative real-time PCR and luminex assay. Pterodontic acid was isolated from L. pterodonta, which showed selective anti-viral activities to H1 subtype of human influenza A virus. Meanwhile, the NA activity was not obviously inhibited by the compound. Further experiments exhibited that the compound can suppress the activation of NF-κB signal pathway and export of viral RNP complexes from the nucleus. In addition, it can significantly attenuate expression of the pro-inflammatory molecules IL-6, MIP-1β, MCP-1, and IP-10 induced by human influenza A virus (H1N1 and similarly downregulate expression of cytokines and chemokines induced by avian influenza A virus (H9N2. This study showed that in vitro antiviral activity of pterodontic acid is most probably associated with inhibiting the replication of influenza A virus by blocking nuclear export of viral RNP complexes, and attenuating the inflammatory response by inhibiting activation of the NF-κB pathway. Pterodontic acid might be a potential antiviral agent against influenza A virus.

  12. Human Cytomegalovirus UL44 Concentrates at the Periphery of Replication Compartments, the Site of Viral DNA Synthesis

    OpenAIRE

    Strang, Blair L.; Boulant, Steeve; Chang, Lynne; Knipe, David M.; Kirchhausen, Tomas; Coen, Donald M.

    2012-01-01

    The formation of replication compartments, the subnuclear structures in which the viral DNA genome is replicated, is a hallmark of herpesvirus infections. The localization of proteins and viral DNA within human cytomegalovirus replication compartments is not well characterized. Immunofluorescence analysis demonstrated the accumulation of the viral DNA polymerase subunit UL44 at the periphery of replication compartments and the presence of different populations of UL44 in infected cells. In co...

  13. COPI activity coupled with fatty acid biosynthesis is required for viral replication.

    Directory of Open Access Journals (Sweden)

    Sara Cherry

    2006-10-01

    Full Text Available During infection by diverse viral families, RNA replication occurs on the surface of virally induced cytoplasmic membranes of cellular origin. How this process is regulated, and which cellular factors are required, has been unclear. Moreover, the host-pathogen interactions that facilitate the formation of this new compartment might represent critical determinants of viral pathogenesis, and their elucidation may lead to novel insights into the coordination of vesicular trafficking events during infection. Here we show that in Drosophila cells, Drosophila C virus remodels the Golgi apparatus and forms a novel vesicular compartment, on the surface of which viral RNA replication takes place. Using genome-wide RNA interference screening, we found that this step in the viral lifecycle requires at least two host encoded pathways: the coat protein complex I (COPI coatamer and fatty acid biosynthesis. Our results integrate, clarify, and extend numerous observations concerning the cell biology of viral replication, allowing us to conclude that the coupling of new cellular membrane formation with the budding of these vesicles from the Golgi apparatus allows for the regulated generation of this new virogenic organelle, which is essential for viral replication. Additionally, because these pathways are also limiting in flies and in human cells infected with the related RNA virus poliovirus, they may represent novel targets for antiviral therapies.

  14. Nordihydroguaiaretic acid (NDGA) inhibits replication and viral morphogenesis of dengue virus.

    Science.gov (United States)

    Soto-Acosta, Rubén; Bautista-Carbajal, Patricia; Syed, Gulam H; Siddiqui, Aleem; Del Angel, Rosa M

    2014-09-01

    Dengue is the most common mosquito borne viral disease in humans. The infection with any of the 4 dengue virus serotypes (DENV) can either be asymptomatic or manifest in two clinical forms, the mild dengue fever or the more severe dengue hemorrhagic fever that may progress into dengue shock syndrome. A DENV replicative cycle relies on host lipid metabolism; specifically, DENV infection modulates cholesterol and fatty acid synthesis, generating a lipid-enriched cellular environment necessary for viral replication. Thus, the aim of this work was to evaluate the anti-DENV effect of the Nordihydroguaiaretic acid (NDGA), a hypolipidemic agent with antioxidant and anti-inflammatory properties. A dose-dependent inhibition in viral yield and NS1 secretion was observed in supernatants of infected cells treated for 24 and 48 h with different concentrations of NDGA. To evaluate the effect of NDGA in DENV replication, a DENV4 replicon transfected Vero cells were treated with different concentrations of NDGA. NDGA treatment significantly reduced DENV replication, reiterating the importance of lipids in viral replication. NDGA treatment also led to reduction in number of lipid droplets (LDs), the neutral lipid storage organelles involved in DENV morphogenesis that are known to increase in number during DENV infection. Furthermore, NDGA treatment resulted in dissociation of the C protein from LDs. Overall our results suggest that NDGA inhibits DENV infection by targeting genome replication and viral assembly. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Uracil DNA glycosylase BKRF3 contributes to Epstein-Barr virus DNA replication through physical interactions with proteins in viral DNA replication complex.

    Science.gov (United States)

    Su, Mei-Tzu; Liu, I-Hua; Wu, Chia-Wei; Chang, Shu-Ming; Tsai, Ching-Hwa; Yang, Pei-Wen; Chuang, Yu-Chia; Lee, Chung-Pei; Chen, Mei-Ru

    2014-08-01

    Epstein-Barr virus (EBV) BKRF3 shares sequence homology with members of the uracil-N-glycosylase (UNG) protein family and has DNA glycosylase activity. Here, we explored how BKRF3 participates in the DNA replication complex and contributes to viral DNA replication. Exogenously expressed Flag-BKRF3 was distributed mostly in the cytoplasm, whereas BKRF3 was translocated into the nucleus and colocalized with the EBV DNA polymerase BALF5 in the replication compartment during EBV lytic replication. The expression level of BKRF3 increased gradually during viral replication, coupled with a decrease of cellular UNG2, suggesting BKRF3 enzyme activity compensates for UNG2 and ensures the fidelity of viral DNA replication. In immunoprecipitation-Western blotting, BKRF3 was coimmuno-precipitated with BALF5, the polymerase processivity factor BMRF1, and the immediate-early transactivator Rta. Coexpression of BMRF1 appeared to facilitate the nuclear targeting of BKRF3 in immunofluorescence staining. Residues 164 to 255 of BKRF3 were required for interaction with Rta and BALF5, whereas residues 81 to 166 of BKRF3 were critical for BMRF1 interaction in glutathione S-transferase (GST) pulldown experiments. Viral DNA replication was defective in cells harboring BKRF3 knockout EBV bacmids. In complementation assays, the catalytic mutant BKRF3(Q90L,D91N) restored viral DNA replication, whereas the leucine loop mutant BKRF3(H213L) only partially rescued viral DNA replication, coupled with a reduced ability to interact with the viral DNA polymerase and Rta. Our data suggest that BKRF3 plays a critical role in viral DNA synthesis predominantly through its interactions with viral proteins in the DNA replication compartment, while its enzymatic activity may be supplementary for uracil DNA glycosylase (UDG) function during virus replication. Catalytic activities of both cellular UDG UNG2 and viral UDGs contribute to herpesviral DNA replication. To ensure that the enzyme activity executes at

  16. Early growth response-1 facilitates enterovirus 71 replication by direct binding to the viral genome RNA.

    Science.gov (United States)

    Song, Yu; Cheng, Xin; Yang, Xiaoxia; Zhao, Rong; Wang, Peili; Han, Yang; Luo, Zhen; Cao, Yanhua; Zhu, Chengliang; Xiong, Ying; Liu, Yingle; Wu, Kailang; Wu, Jianguo

    2015-05-01

    Enterovirus 71 (EV71) infections can cause hand, foot and mouth disease (HFMD), meningoencephalitis, neonatal sepsis, and even fatal encephalitis in children. Unfortunately, there is currently no effective treatment for EV71 infection due to the lack of understanding of viral replication and infection; and viral infections have emerged as an imperative global hazard. Thus, it is extremely important to understand the mechanism of EV71 replication in order to prevent and control the diseases associated with EV71 infections. Early growth response-1 (EGR1) is a multifunctional transcription factor that regulates diverse biological functions, including inflammation, apoptosis, differentiation, tumorigenesis, and even viral infection. Here, we provide new insight into the role of EV71 infection in regulating EGR1 production; and reveal a novel mechanism by which EGR1 facilitates EV71 replication. We demonstrate that EV71 activates EGR1 expression during infection by stimulating the protein kinase A/protein kinase Cɛ/phosphoinositide 3-kinase/Akt (PKA/PKCɛ/PI3K/Akt) cascade. We further reveal that EV71-activated EGR1, in turn, regulates the internal ribosomal entry site (IRES) of EV71 to enhance viral replication. In addition, EGR1 facilitates EV71 replication by binding directly to stem-loops I and IV of EV71 5'-untranslated region (5'UTR) with its first two zinc fingers. Moreover, EGR1 protein co-localizes with EV71 RNA in the cytoplasm of infected cells to facilitate viral replication. Our results reveal an important new role of EGR1 in viral infection, provide new insight into the novel mechanism underlying the regulation of EV71 replication, and suggest a potential application of EGR1 in the control of EV71 infection. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. JC virus agnoprotein enhances large T antigen binding to the origin of viral DNA replication: evidence for its involvement in viral DNA replication.

    Science.gov (United States)

    Saribas, A Sami; White, Martyn K; Safak, Mahmut

    2012-11-10

    Agnoprotein is required for the successful completion of the JC virus (JCV) life cycle and was previously shown to interact with JCV large T-antigen (LT-Ag). Here, we further characterized agnoprotein's involvement in viral DNA replication. Agnoprotein enhances the DNA binding activity of LT-Ag to the viral origin (Ori) without directly interacting with DNA. The predicted amphipathic α-helix of agnoprotein plays a major role in this enhancement. All three phenylalanine (Phe) residues of agnoprotein localize to this α-helix and Phe residues in general are known to play critical roles in protein-protein interaction, protein folding and stability. The functional relevance of all Phe residues was investigated by mutagenesis. When all were mutated to alanine (Ala), the mutant virus (F31AF35AF39A) replicated significantly less efficiently than each individual Phe mutant virus alone, indicating the importance of Phe residues for agnoprotein function. Collectively, these studies indicate a close involvement of agnoprotein in viral DNA replication. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Oligomerization of Baculovirus LEF-11 Is Involved in Viral DNA Replication.

    Science.gov (United States)

    Dong, Zhan-Qi; Hu, Nan; Zhang, Jun; Chen, Ting-Ting; Cao, Ming-Ya; Li, Hai-Qing; Lei, Xue-Jiao; Chen, Peng; Lu, Cheng; Pan, Min-Hui

    2015-01-01

    We have previously reported that baculovirus Bombyx mori nucleopolyhedrovirus (BmNPV) late expression factor 11 (lef-11) is associated with viral DNA replication and have demonstrated that it potentially interacts with itself; however, whether LEF-11 forms oligomers and the impact of LEF-11 oligomerization on viral function have not been substantiated. In this study, we first demonstrated that LEF-11 is capable of forming oligomers. Additionally, a series of analyses using BmNPV LEF-11 truncation mutants indicated that two distinct domains control LEF-11 oligomerization (aa 42-61 and aa 72-101). LEF-11 truncation constructs were inserted into a lef-11-knockout BmNPV bacmid, which was used to demonstrate that truncated LEF-11 lacking either oligomerization domain abrogates viral DNA replication. Finally, site-directed mutagenesis was used to determine that the conserved hydrophobic residues Y58&I59 (representing Y58 and I59), I85 and L88&L89 (representing L88 and L89) are required for LEF-11 oligomerization and viral DNA replication. Collectively, these data indicate that BmNPV LEF-11 oligomerization influences viral DNA replication.

  19. Viral and Cellular Determinants of Hepatitis C Virus RNA Replication in Cell Culture

    Science.gov (United States)

    Lohmann, Volker; Hoffmann, Sandra; Herian, Ulrike; Penin, Francois; Bartenschlager, Ralf

    2003-01-01

    Studies on the replication of hepatitis C virus (HCV) have been facilitated by the development of selectable subgenomic replicons replicating in the human hepatoma cell line Huh-7 at a surprisingly high level. Analysis of the replicon population in selected cells revealed the occurrence of cell culture-adaptive mutations that enhance RNA replication substantially. To gain a better understanding of HCV cell culture adaptation, we characterized conserved mutations identified by sequence analysis of 26 independent replicon cell clones for their effect on RNA replication. Mutations enhancing replication were found in nearly every nonstructural (NS) protein, and they could be subdivided into at least two groups by their effect on replication efficiency and cooperativity: (i) mutations in NS3 with a low impact on replication but that enhanced replication cooperatively when combined with highly adaptive mutations and (ii) mutations in NS4B, -5A, and -5B, causing a strong increase in replication but being incompatible with each other. In addition to adaptive mutations, we found that the host cell plays an equally important role for efficient RNA replication. We tested several passages of the same Huh-7 cell line and found up to 100-fold differences in their ability to support replicon amplification. These differences were not due to variations in internal ribosome entry site-dependent translation or RNA degradation. In a search for cellular factor(s) that might be responsible for the different levels of permissiveness of Huh-7 cells, we found that replication efficiency decreased with increasing amounts of transfected replicon RNA, indicating that viral RNA or proteins are cytopathic or that host cell factors in Huh-7 cells limit RNA amplification. In summary, these data show that the efficiency of HCV replication in cell culture is determined both by adaptation of the viral sequence and by the host cell itself. PMID:12584326

  20. Response of sublethally irradiated monkeys to a replicating viral antigen

    International Nuclear Information System (INIS)

    Hilmas, D.E.; Spertzel, R.O.

    1975-01-01

    Temporal effects of exposure to sublethal, total-body x radiation (400 R) on responses to vaccination with the attenuated Venezuelan equine encephalomyelitis vaccine virus, TC-83, were examined in rhesus monkeys. Viremia, often with delayed onset, was prolonged even when irradiation preceded vaccination by 28 days. Virus titers were increased, particularly in groups irradiated 4 or 7 days before vaccination. Delay in appearance of hemagglutination-inhibition and serum-neutralizing antibody correlated closely with persistence of viremia in irradiated-vaccinated monkeys. The temporal course of antibody response was markedly affected by the interval between irradiation and injection of this replicating antigen. With longer intervals between irradiation and vaccination, the somewhat depressed antibody responses approached normal or surpassed those of nonirradiated monkeys. Vaccination 14 days after radiation exposure resulted in lethality to 8 of 12 monkeys, apparently as a result of secondary infection. The additional lymphopenic stress due to the effect of TC-83, superimposed on the severely depressed hematopoietic competence at 14 days, undoubtedly contributed to this increased susceptibility to latent infection

  1. A Functional Role of Fibroblast Growth Factor Receptor 1 (FGFR1 in the Suppression of Influenza A Virus Replication.

    Directory of Open Access Journals (Sweden)

    Xin Liu

    Full Text Available Influenza A virus causes annual epidemics and occasional pandemics in humans. Here, we investigated four members of the fibroblast growth factor receptor (FGFR family; FGFR1 to 4, and examined their expression patterns in human lung epithelial cells A549 with influenza A virus infection. We identified a functional role of FGFR1 in influenza A/Puerto Rico/8/1934 (PR8 and A/Anhui/01/2005 (H5N1 virus replication. Our results showed that FGFR1 silencing by siRNA interference promoted influenza A/PR8 and H5N1 virus replication in A549 cells, while lentivirus-mediated exogenous FGFR1 expression significantly suppressed influenza A virus replication; however, FGFR4 did not have the same effects. Moreover, FGFR1 phosphorylation levels were downregulated in A549 cells by influenza A virus infection, while the repression of FGFR1 kinase using PD173074, a potent and selective FGFR1 inhibitor, could enhance virus replication. Furthermore, we found that FGFR1 inhibits influenza virus internalization, but not binding, during viral entry. These results suggested that FGFR1 specifically antagonizes influenza A virus replication, probably by blocking viral entry.

  2. Human Cytomegalovirus Can Procure Deoxyribonucleotides for Viral DNA Replication in the Absence of Retinoblastoma Protein Phosphorylation.

    Science.gov (United States)

    Kuny, Chad V; Kalejta, Robert F

    2016-10-01

    Viral DNA replication requires deoxyribonucleotide triphosphates (dNTPs). These molecules, which are found at low levels in noncycling cells, are generated either by salvage pathways or through de novo synthesis. Nucleotide synthesis utilizes the activity of a series of nucleotide-biosynthetic enzymes (NBEs) whose expression is repressed in noncycling cells by complexes between the E2F transcription factors and the retinoblastoma (Rb) tumor suppressor. Rb-E2F complexes are dissociated and NBE expression is activated during cell cycle transit by cyclin-dependent kinase (Cdk)-mediated Rb phosphorylation. The DNA virus human cytomegalovirus (HCMV) encodes a viral Cdk (v-Cdk) (the UL97 protein) that phosphorylates Rb, induces the expression of cellular NBEs, and is required for efficient viral DNA synthesis. A long-held hypothesis proposed that viral proteins with Rb-inactivating activities functionally similar to those of UL97 facilitated viral DNA replication in part by inducing the de novo production of dNTPs. However, we found that dNTPs were limiting even in cells infected with wild-type HCMV in which UL97 is expressed and Rb is phosphorylated. Furthermore, we revealed that both de novo and salvage pathway enzymes contribute to viral DNA replication during HCMV infection and that Rb phosphorylation by cellular Cdks does not correct the viral DNA replication defect observed in cells infected with a UL97-deficient virus. We conclude that HCMV can obtain dNTPs in the absence of Rb phosphorylation and that UL97 can contribute to the efficiency of DNA replication in an Rb phosphorylation-independent manner. Transforming viral oncoproteins, such as adenovirus E1A and papillomavirus E7, inactivate Rb. The standard hypothesis for how Rb inactivation facilitates infection with these viruses is that it is through an increase in the enzymes required for DNA synthesis, which include nucleotide-biosynthetic enzymes. However, HCMV UL97, which functionally mimics these viral

  3. Viral gene products and replication of the human immunodeficiency type 1 virus.

    Science.gov (United States)

    Morrow, C D; Park, J; Wakefield, J K

    1994-05-01

    The acquired immunodeficiency syndrome (AIDS) epidemic represents a modern-day plague that has not only resulted in a tragic loss of people from a wide spectrum of society but has reshaped our viewpoints regarding health care, the treatment of infectious diseases, and social issues regarding sexual behavior. There is little doubt now that the cause of the disease AIDS is a virus known as the human immunodeficiency virus (HIV). The HIV virus is a member of a large family of viruses termed retroviruses, which have as a hallmark the capacity to convert their RNA genome into a DNA form that then undergoes a process of integration into the host cell chromosome, followed by the expression of the viral genome and translation of viral proteins in the infected cell. This review describes the organization of the HIV-1 viral genome, the expression of viral proteins, as well as the functions of the accessory viral proteins in HIV replication. The replication of the viral genome is divided into two phases, the early phase and the late phase. The early phase consists of the interaction of the virus with the cell surface receptor (CD4 molecule in most cases), the uncoating and conversion of the viral RNA genome into a DNA form, and the integration into the host cell chromosome. The late phase consists of the expression of the viral proteins from the integrated viral genome, the translation of viral proteins, and the assembly and release of the virus. Points in the HIV-1 life cycle that are targets for therapeutic intervention are also discussed.

  4. Baculovirus LEF-11 nuclear localization signal is important for viral DNA replication.

    Science.gov (United States)

    Chen, Tingting; Dong, Zhanqi; Hu, Nan; Hu, Zhigang; Dong, Feifan; Jiang, Yaming; Li, Jun; Chen, Peng; Lu, Cheng; Pan, Minhui

    2017-06-15

    Baculovirus LEF-11 is a small nuclear protein that is involved in viral late gene transcription and DNA replication. However, the characteristics of its nuclear localization signal and its impact on viral DNA replication are unknown. In the present study, systemic bioinformatics analysis showed that the baculovirus LEF-11 contains monopartite and bipartite classical nuclear localization signal sequences (cNLSs), which were also detected in a few alphabaculovirus species. Localization of representative LEF-11 proteins of four baculovirus genera indicated that the nuclear localization characteristics of baculovirus LEF-11 coincided with the predicted results. Moreover, Bombyx mori nucleopolyhedrovirus (BmNPV) LEF-11 could be transported into the nucleus during viral infection in the absence of a cNLSs. Further investigations demonstrated that the NLS of BmNPV LEF-11 is important for viral DNA replication. The findings of the present study indicate that the characteristics of the baculovirus LEF-11 protein and the NLS is essential to virus DNA replication and nuclear transport mechanisms. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Manipulating 3D-Printed and Paper Models Enhances Student Understanding of Viral Replication

    Science.gov (United States)

    Couper, Lisa; Johannes, Kristen; Powers, Jackie; Silberglitt, Matt; Davenport, Jodi

    2016-01-01

    Understanding key concepts in molecular biology requires reasoning about molecular processes that are not directly observable and, as such, presents a challenge to students and teachers. We ask whether novel interactive physical models and activities can help students understand key processes in viral replication. Our 3D tangible models are…

  6. Replication of an incomplete alfalfa mosaic virus genome in plants transformed with viral replicase genes

    NARCIS (Netherlands)

    Taschner, P. E.; van der Kuyl, A. C.; Neeleman, L.; Bol, J. F.

    1991-01-01

    RNAs 1 and 2 of alfalfa mosaic virus (AIMV) encode proteins P1 and P2, respectively, both of which have a putative role in viral RNA replication. Tobacco plants were transformed with DNA copies of RNA1 (P1-plants), RNA2 (P2-plants) or a combination of these two cDNAs (P12-plants). All transgenic

  7. Influenza Virus Induces Inflammatory Response in Mouse Primary Cortical Neurons with Limited Viral Replication.

    Science.gov (United States)

    Wang, Gefei; Li, Rui; Jiang, Zhiwu; Gu, Liming; Chen, Yanxia; Dai, Jianping; Li, Kangsheng

    2016-01-01

    Unlike stereotypical neurotropic viruses, influenza A viruses have been detected in the brain tissues of human and animal models. To investigate the interaction between neurons and influenza A viruses, mouse cortical neurons were isolated, infected with human H1N1 influenza virus, and then examined for the production of various inflammatory molecules involved in immune response. We found that replication of the influenza virus in neurons was limited, although early viral transcription was not affected. Virus-induced neuron viability decreased at 6 h postinfection (p.i.) but increased at 24 h p.i. depending upon the viral strain. Virus-induced apoptosis and cytopathy in primary cortical neurons were not apparent at 24 h p.i. The mRNA levels of inflammatory cytokines, chemokines, and type I interferons were upregulated at 6 h and 24 h p.i. These results indicate that the influenza virus induces inflammatory response in mouse primary cortical neurons with limited viral replication. The cytokines released in viral infection-induced neuroinflammation might play critical roles in influenza encephalopathy, rather than in viral replication-induced cytopathy.

  8. Influenza Virus Induces Inflammatory Response in Mouse Primary Cortical Neurons with Limited Viral Replication

    Directory of Open Access Journals (Sweden)

    Gefei Wang

    2016-01-01

    Full Text Available Unlike stereotypical neurotropic viruses, influenza A viruses have been detected in the brain tissues of human and animal models. To investigate the interaction between neurons and influenza A viruses, mouse cortical neurons were isolated, infected with human H1N1 influenza virus, and then examined for the production of various inflammatory molecules involved in immune response. We found that replication of the influenza virus in neurons was limited, although early viral transcription was not affected. Virus-induced neuron viability decreased at 6 h postinfection (p.i. but increased at 24 h p.i. depending upon the viral strain. Virus-induced apoptosis and cytopathy in primary cortical neurons were not apparent at 24 h p.i. The mRNA levels of inflammatory cytokines, chemokines, and type I interferons were upregulated at 6 h and 24 h p.i. These results indicate that the influenza virus induces inflammatory response in mouse primary cortical neurons with limited viral replication. The cytokines released in viral infection-induced neuroinflammation might play critical roles in influenza encephalopathy, rather than in viral replication-induced cytopathy.

  9. IL-9 inhibits viral replication in Coxsackievirus B3-induced myocarditis

    Directory of Open Access Journals (Sweden)

    Miao Yu

    2016-10-01

    Full Text Available Myocardial injuries in viral myocarditis (VMC are caused by viral infection and related autoimmune disorders. Recent studies suggest that IL-9 mediated both antimicrobial immune and autoimmune responses in addition to allergic diseases. However, the role of IL-9 in viral infection and VMC remains controversial and uncertain. In this study, we infected Balb/c mice with Coxsackievirus B3 (CVB3, and found that IL-9 was enriched in the blood and hearts of VMC mice on days 5 and 7 after virus infection. Most of IL-9 was secreted by CD8+ T cells on day 5 and CD4+ T cells on day 7 in the myocardium. Further, IL-9 knockout exacerbated cardiac damage following CVB3 infection, along with a sharp increase in viral replication and IL-17a expression, as well as a decrease in TGF-β. In contrast, repletion of IL-9 in Balb/c mice with CVB infection induced the opposite effect. Studies in vitro further revealed that IL-9 directly inhibited viral replication in cardiomyocytes by reducing coxsackie and adenovirus receptor expression, which might be associated with up-regulation of TGF-β autocrine effect in these cells. However, IL-9 had no direct effect on apoptosis in cardiomyocytes. Our data indicated that IL-9 played a protective role in disease progression by inhibiting CVB3 replication in the early stages of VMC.

  10. Insights into the functional characteristics of geminivirus rolling-circle replication initiator protein and its interaction with host factors affecting viral DNA replication.

    Science.gov (United States)

    Rizvi, Irum; Choudhury, Nirupam Roy; Tuteja, Narendra

    2015-02-01

    Geminiviruses are DNA viruses that infect several economically important crops, resulting in a reduction in their overall yield. These plant viruses have circular, single-stranded DNA genomes that replicate mainly by a rolling-circle mechanism. Geminivirus infection results in crosstalk between viral and cellular factors to complete the viral life cycle or counteract the infection as part of defense mechanisms of host plants. The geminiviral replication initiator protein Rep is the only essential viral factor required for replication. It is multifunctional and is known to interact with a number of host factors to modulate the cellular environment or to function as a part of the replication machinery. This review provides a holistic view of the research related to the viral Rep protein and various host factors involved in geminiviral DNA replication. Studies on the promiscuous nature of geminiviral satellite DNAs are also reviewed.

  11. Suppression of Zika Virus Infection and Replication in Endothelial Cells and Astrocytes by PKA Inhibitor PKI 14-22.

    Science.gov (United States)

    Cheng, Fan; Ramos da Silva, Suzane; Huang, I-Chueh; Jung, Jae U; Gao, Shou-Jiang

    2018-02-15

    The recent outbreak of Zika virus (ZIKV), a reemerging flavivirus, and its associated neurological disorders, such as Guillain-Barré (GB) syndrome and microcephaly, have generated an urgent need to develop effective ZIKV vaccines and therapeutic agents. Here, we used human endothelial cells and astrocytes, both of which represent key cell types for ZIKV infection, to identify potential inhibitors of ZIKV replication. Because several pathways, including the AMP-activated protein kinase (AMPK), protein kinase A (PKA), and mitogen-activated protein kinase (MAPK) signaling pathways, have been reported to play important roles in flavivirus replication, we tested inhibitors and agonists of these pathways for their effects on ZIKV replication. We identified the PKA inhibitor PKI 14-22 (PKI) to be a potent inhibitor of ZIKV replication. PKI effectively suppressed the replication of ZIKV from both the African and Asian/American lineages with a high efficiency and minimal cytotoxicity. While ZIKV infection does not induce PKA activation, endogenous PKA activity is essential for supporting ZIKV replication. Interestingly, in addition to PKA, PKI also inhibited another unknown target(s) to block ZIKV replication. PKI inhibited ZIKV replication at the postentry stage by preferentially affecting negative-sense RNA synthesis as well as viral protein translation. Together, these results have identified a potential inhibitor of ZIKV replication which could be further explored for future therapeutic application. IMPORTANCE There is an urgent need to develop effective vaccines and therapeutic agents against Zika virus (ZIKV) infection, a reemerging flavivirus associated with neurological disorders, including Guillain-Barré (GB) syndrome and microcephaly. By screening for inhibitors of several cellular pathways, we have identified the PKA inhibitor PKI 14-22 (PKI) to be a potent inhibitor of ZIKV replication. We show that PKI effectively suppresses the replication of all ZIKV

  12. Viral DNA replication-dependent DNA damage response activation during BK polyomavirus infection.

    Science.gov (United States)

    Verhalen, Brandy; Justice, Joshua L; Imperiale, Michael J; Jiang, Mengxi

    2015-05-01

    BK polyomavirus (BKPyV) reactivation is associated with severe human disease in kidney and bone marrow transplant patients. The interplay between viral and host factors that regulates the productive infection process remains poorly understood. We have previously reported that the cellular DNA damage response (DDR) is activated upon lytic BKPyV infection and that its activation is required for optimal viral replication in primary kidney epithelial cells. In this report, we set out to determine what viral components are responsible for activating the two major phosphatidylinositol 3-kinase-like kinases (PI3KKs) involved in the DDR: ataxia telangiectasia mutated (ATM) kinase and ATM and Rad3-related (ATR) kinase. Using a combination of UV treatment, lentivirus transduction, and mutant virus infection experiments, our results demonstrate that neither the input virus nor the expression of large T antigen (TAg) alone is sufficient to trigger the activation of ATM or ATR in our primary culture model. Instead, our data suggest that the activation of both the ATM- and ATR-mediated DDR pathways is linked to viral DNA replication. Intriguingly, a TAg mutant virus that is unable to activate the DDR causes substantial host DNA damage. Our study provides insight into how DDRs are activated by polyomaviruses in primary cells with intact cell cycle checkpoints and how the activation might be linked to the maintenance of host genome stability. Polyomaviruses are opportunistic pathogens that are associated with several human diseases under immunosuppressed conditions. BK polyomavirus (BKPyV) affects mostly kidney and bone marrow transplant patients. The detailed replication mechanism of these viruses remains to be determined. We have previously reported that BKPyV activates the host DNA damage response (DDR), a response normally used by the host cell to combat genotoxic stress, to aid its own replication. In this study, we identified that the trigger for DDR activation is viral

  13. ACH-806, an NS4A antagonist, inhibits hepatitis C virus replication by altering the composition of viral replication complexes.

    Science.gov (United States)

    Yang, Wengang; Sun, Yongnian; Hou, Xiaohong; Zhao, Yongsen; Fabrycki, Joanne; Chen, Dawei; Wang, Xiangzhu; Agarwal, Atul; Phadke, Avinash; Deshpande, Milind; Huang, Mingjun

    2013-07-01

    Treatment of hepatitis C patients with direct-acting antiviral drugs involves the combination of multiple small-molecule inhibitors of distinctive mechanisms of action. ACH-806 (or GS-9132) is a novel, small-molecule inhibitor specific for hepatitis C virus (HCV). It inhibits viral RNA replication in HCV replicon cells and was active in genotype 1 HCV-infected patients in a proof-of-concept clinical trial (1). Here, we describe a potential mechanism of action (MoA) wherein ACH-806 alters viral replication complex (RC) composition and function. We found that ACH-806 did not affect HCV polyprotein translation and processing, the early events of the formation of HCV RC. Instead, ACH-806 triggered the formation of a homodimeric form of NS4A with a size of 14 kDa (p14) both in replicon cells and in Huh-7 cells where NS4A was expressed alone. p14 production was negatively regulated by NS3, and its appearance in turn was associated with reductions in NS3 and, especially, NS4A content in RCs due to their accelerated degradation. A previously described resistance substitution near the N terminus of NS3, where NS3 interacts with NS4A, attenuated the reduction of NS3 and NS4A conferred by ACH-806 treatment. Taken together, we show that the compositional changes in viral RCs are associated with the antiviral activity of ACH-806. Small molecules, including ACH-806, with this novel MoA hold promise for further development and provide unique tools for clarifying the functions of NS4A in HCV replication.

  14. Synergistic Effect of Hyperglycemia and Suppression on Adult Mouse Islet Beta Cell Replication

    Directory of Open Access Journals (Sweden)

    Szu-Tah Chen

    2012-01-01

    Full Text Available The complementary role of hyperglycemia and suppression on islet beta cell regeneration was investigated in a syngeneic mouse model. gene silencing was performed by infecting islets of C57BL/6 with shRNA lentiviral particles. At 54 hours after viral infection, protein content in cultured targeting islets was 22% of that in freshly isolated islets. Six days after transplantation to diabetic mice, targeting islet graft had considerably more cells with Ki67-staining nuclei than nontargeting islets. The mice in the targeting-islet group had a significantly shorter duration of temporary hyperglycaemia than mice in the non-targeting-islet group. The long-term ex vivo beneficial effect of silencing on graft function was also indicated by the significantly higher cumulative cure rate for diabetes in mice receiving 200 targeting islets than that in mice receiving 200 non-targeting islets. Our data suggest that hyperglycemia and persistent suppression have a synergistic effect on islet beta cell replication in adult mice.

  15. Viral hijacking of a replicative helicase loader and its implications for helicase loading control and phage replication

    Energy Technology Data Exchange (ETDEWEB)

    Hood, Iris V.; Berger, James M.

    2016-05-31

    Replisome assembly requires the loading of replicative hexameric helicases onto origins by AAA+ ATPases. How loader activity is appropriately controlled remains unclear. Here, we use structural and biochemical analyses to establish how an antimicrobial phage protein interferes with the function of theStaphylococcus aureusreplicative helicase loader, DnaI. The viral protein binds to the loader’s AAA+ ATPase domain, allowing binding of the host replicative helicase but impeding loader self-assembly and ATPase activity. Close inspection of the complex highlights an unexpected locus for the binding of an interdomain linker element in DnaI/DnaC-family proteins. We find that the inhibitor protein is genetically coupled to a phage-encoded homolog of the bacterial helicase loader, which we show binds to the host helicase but not to the inhibitor itself. These findings establish a new approach by which viruses can hijack host replication processes and explain how loader activity is internally regulated to prevent aberrant auto-association.

  16. Interaction of CtBP with adenovirus E1A suppresses immortalization of primary epithelial cells and enhances virus replication during productive infection

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, T.; Zhao, Ling-jun; Chinnadurai, G., E-mail: chinnag@slu.edu

    2013-09-01

    Adenovirus E1A induces cell proliferation, oncogenic transformation and promotes viral replication through interaction with p300/CBP, TRRAP/p400 multi-protein complex and the retinoblastoma (pRb) family proteins through distinct domains in the E1A N-terminal region. The C-terminal region of E1A suppresses E1A/Ras co-transformation and interacts with FOXK1/K2, DYRK1A/1B/HAN11 and CtBP1/2 (CtBP) protein complexes. To specifically dissect the role of CtBP interaction with E1A, we engineered a mutation (DL→AS) within the CtBP-binding motif, PLDLS, and investigated the effect of the mutation on immortalization and Ras cooperative transformation of primary cells and viral replication. Our results suggest that CtBP–E1A interaction suppresses immortalization and Ras co-operative transformation of primary rodent epithelial cells without significantly influencing the tumorigenic activities of transformed cells in immunodeficient and immunocompetent animals. During productive infection, CtBP–E1A interaction enhances viral replication in human cells. Between the two CtBP family proteins, CtBP2 appears to restrict viral replication more than CtBP1 in human cells. - Highlights: • Adenovirus E1A C-terminal region suppresses E1A/Ras co-transformation. • This E1A region binds with FOXK, DYRK1/HAN11 and CtBP cellular protein complexes. • We found that E1A–CtBP interaction suppresses immortalization and transformation. • The interaction enhances viral replication in human cells.

  17. Simian Immunodeficiency Virus (SIV-Specific Chimeric Antigen Receptor-T Cells Engineered to Target B Cell Follicles and Suppress SIV Replication

    Directory of Open Access Journals (Sweden)

    Kumudhini Preethi Haran

    2018-03-01

    Full Text Available There is a need to develop improved methods to treat and potentially cure HIV infection. During chronic HIV infection, replication is concentrated within T follicular helper cells (Tfh located within B cell follicles, where low levels of virus-specific CTL permit ongoing viral replication. We previously showed that elevated levels of simian immunodeficiency virus (SIV-specific CTL in B cell follicles are linked to both decreased levels of viral replication in follicles and decreased plasma viral loads. These findings provide the rationale to develop a strategy for targeting follicular viral-producing (Tfh cells using antiviral chimeric antigen receptor (CAR T cells co-expressing the follicular homing chemokine receptor CXCR5. We hypothesize that antiviral CAR/CXCR5-expressing T cells, when infused into an SIV-infected animal or an HIV-infected individual, will home to B cell follicles, suppress viral replication, and lead to long-term durable remission of SIV and HIV. To begin to test this hypothesis, we engineered gammaretroviral transduction vectors for co-expression of a bispecific anti-SIV CAR and rhesus macaque CXCR5. Viral suppression by CAR/CXCR5-transduced T cells was measured in vitro, and CXCR5-mediated migration was evaluated using both an in vitro transwell migration assay, as well as a novel ex vivo tissue migration assay. The functionality of the CAR/CXCR5 T cells was demonstrated through their potent suppression of SIVmac239 and SIVE660 replication in in vitro and migration to the ligand CXCL13 in vitro, and concentration in B cell follicles in tissues ex vivo. These novel antiviral immunotherapy products have the potential to provide long-term durable remission (functional cure of HIV and SIV infections.

  18. In vitro inhibition of African swine fever virus-topoisomerase II disrupts viral replication.

    Science.gov (United States)

    Freitas, Ferdinando B; Frouco, Gonçalo; Martins, Carlos; Leitão, Alexandre; Ferreira, Fernando

    2016-10-01

    African swine fever virus (ASFV) is the etiological agent of a highly-contagious and fatal disease of domestic pigs, leading to serious socio-economic impact in affected countries. To date, neither a vaccine nor a selective anti-viral drug are available for prevention or treatment of African swine fever (ASF), emphasizing the need for more detailed studies at the role of ASFV proteins involved in viral DNA replication and transcription. Notably, ASFV encodes for a functional type II topoisomerase (ASFV-Topo II) and we recently showed that several fluoroquinolones (bacterial DNA topoisomerase inhibitors) fully abrogate ASFV replication in vitro. Here, we report that ASFV-Topo II gene is actively transcribed throughout infection, with transcripts being detected as early as 2 hpi and reaching a maximum peak concentration around 16 hpi, when viral DNA synthesis, transcription and translation are more active. siRNA knockdown experiments showed that ASFV-Topo II plays a critical role in viral DNA replication and gene expression, with transfected cells presenting lower viral transcripts (up to 89% decrease) and reduced cytopathic effect (-66%) when compared to the control group. Further, a significant decrease in the number of both infected cells (75.5%) and viral factories per cell and in virus yields (up to 99.7%, 2.5 log) was found only in cells transfected with siRNA targeting ASFV-Topo II. We also demonstrate that a short exposure to enrofloxacin during the late phase of infection (from 15 to 1 hpi) induces fragmentation of viral genomes, whereas no viral genomes were detected when enrofloxacin was added from the early phase of infection (from 2 to 16 hpi), suggesting that fluoroquinolones are ASFV-Topo II poisons. Altogether, our results demonstrate that ASFV-Topo II enzyme has an essential role during viral genome replication and transcription, emphasizing the idea that this enzyme can be a potential target for drug and vaccine development against ASF

  19. Automatic detection and measurement of viral replication compartments by ellipse adjustment

    Science.gov (United States)

    Garcés, Yasel; Guerrero, Adán; Hidalgo, Paloma; López, Raul Eduardo; Wood, Christopher D.; Gonzalez, Ramón A.; Rendón-Mancha, Juan Manuel

    2016-11-01

    Viruses employ a variety of strategies to hijack cellular activities through the orchestrated recruitment of macromolecules to specific virus-induced cellular micro-environments. Adenoviruses (Ad) and other DNA viruses induce extensive reorganization of the cell nucleus and formation of nuclear Replication Compartments (RCs), where the viral genome is replicated and expressed. In this work an automatic algorithm designed for detection and segmentation of RCs using ellipses is presented. Unlike algorithms available in the literature, this approach is deterministic, automatic, and can adjust multiple RCs using ellipses. The proposed algorithm is non iterative, computationally efficient and is invariant to affine transformations. The method was validated over both synthetic images and more than 400 real images of Ad-infected cells at various timepoints of the viral replication cycle obtaining relevant information about the biogenesis of adenoviral RCs. As proof of concept the algorithm was then used to quantitatively compare RCs in cells infected with the adenovirus wild type or an adenovirus mutant that is null for expression of a viral protein that is known to affect activities associated with RCs that result in deficient viral progeny production.

  20. Dissecting the role of the ϕ29 terminal protein DNA binding residues in viral DNA replication.

    Science.gov (United States)

    Holguera, Isabel; Muñoz-Espín, Daniel; Salas, Margarita

    2015-03-11

    Phage ϕ29 DNA replication takes place by a protein-priming mechanism in which the viral DNA polymerase catalyses the covalent linkage of the initiating nucleotide to a specific serine residue of the terminal protein (TP). The N-terminal domain of the ϕ29 TP has been shown to bind to the host DNA in a sequence-independent manner and this binding is essential for the TP nucleoid localisation and for an efficient viral DNA replication in vivo. In the present work we have studied the involvement of the TP N-terminal domain residues responsible for DNA binding in the different stages of viral DNA replication by assaying the in vitro activity of purified TP N-terminal mutant proteins. The results show that mutation of TP residues involved in DNA binding affects the catalytic activity of the DNA polymerase in initiation, as the Km for the initiating nucleotide is increased when these mutant proteins are used as primers. Importantly, this initiation defect was relieved by using the ϕ29 double-stranded DNA binding protein p6 in the reaction, which decreased the Km of the DNA polymerase for dATP about 130-190 fold. Furthermore, the TP N-terminal domain was shown to be required both for a proper interaction with the DNA polymerase and for an efficient viral DNA amplification. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  1. Cardiac Fibroblasts Aggravate Viral Myocarditis: Cell Specific Coxsackievirus B3 Replication

    Directory of Open Access Journals (Sweden)

    Diana Lindner

    2014-01-01

    Full Text Available Myocarditis is an inflammatory disease caused by viral infection. Different subpopulations of leukocytes enter the cardiac tissue and lead to severe cardiac inflammation associated with myocyte loss and remodeling. Here, we study possible cell sources for viral replication using three compartments of the heart: fibroblasts, cardiomyocytes, and macrophages. We infected C57BL/6j mice with Coxsackievirus B3 (CVB3 and detected increased gene expression of anti-inflammatory and antiviral cytokines in the heart. Subsequently, we infected cardiac fibroblasts, cardiomyocytes, and macrophages with CVB3. Due to viral infection, the expression of TNF-α, IL-6, MCP-1, and IFN-β was significantly increased in cardiac fibroblasts compared to cardiomyocytes or macrophages. We found that in addition to cardiomyocytes cardiac fibroblasts were infected by CVB3 and displayed a higher virus replication (132-fold increase compared to cardiomyocytes (14-fold increase between 6 and 24 hours after infection. At higher virus concentrations, macrophages are able to reduce the viral copy number. At low virus concentration a persistent virus infection was determined. Therefore, we suggest that cardiac fibroblasts play an important role in the pathology of CVB3-induced myocarditis and are another important contributor of virus replication aggravating myocarditis.

  2. Host DNA damage response factors localize to merkel cell polyomavirus DNA replication sites to support efficient viral DNA replication.

    Science.gov (United States)

    Tsang, Sabrina H; Wang, Xin; Li, Jing; Buck, Christopher B; You, Jianxin

    2014-03-01

    Accumulating evidence indicates a role for Merkel cell polyomavirus (MCPyV) in the development of Merkel cell carcinoma (MCC), making MCPyV the first polyomavirus to be clearly associated with human cancer. With the high prevalence of MCPyV infection and the increasing amount of MCC diagnosis, there is a need to better understand the virus and its oncogenic potential. In this study, we examined the relationship between the host DNA damage response (DDR) and MCPyV replication. We found that components of the ATM- and ATR-mediated DDR pathways accumulate in MCPyV large T antigen (LT)-positive nuclear foci in cells infected with native MCPyV virions. To further study MCPyV replication, we employed our previously established system, in which recombinant MCPyV episomal DNA is autonomously replicated in cultured cells. Similar to native MCPyV infection, where both MCPyV origin and LT are present, the host DDR machinery colocalized with LT in distinct nuclear foci. Immunofluorescence in situ hybridization and bromodeoxyuridine (BrdU) incorporation analysis showed that these DDR proteins and MCPyV LT in fact colocalized at the actively replicating MCPyV replication complexes, which were absent when a replication-defective LT mutant or an MCPyV-origin mutant was introduced in place of wild-type LT or wild-type viral origin. Inhibition of DDR kinases using chemical inhibitors and ATR/ATM small interfering RNA (siRNA) knockdown reduced MCPyV DNA replication without significantly affecting LT expression or the host cell cycle. This study demonstrates that these host DDR factors are important for MCPyV DNA replication, providing new insight into the host machinery involved in the MCPyV life cycle. MCPyV is the first polyomavirus to be clearly associated with human cancer. However, the MCPyV life cycle and its oncogenic mechanism remain poorly understood. In this report, we show that, in cells infected with native MCPyV virions, components of the ATM- and ATR-mediated DDR

  3. Infectious bursal disease virus as a replication-incompetent viral vector expressing green fluorescent protein.

    Science.gov (United States)

    Mosley, Yung-Yi C; Wu, Ching Ching; Lin, Tsang Long

    2017-01-01

    Infectious bursal disease virus (IBDV) has been established as a replication-competent viral vector capable of carrying an epitope at multiple loci in the genome. To enhance the safety and increase the insertion capacity of IBDV as a vector, a replication-incompetent IBDV vector was developed in the present study. The feasibility of replacing one of the viral gene loci, including pvp2, vp3, vp1, or the polyprotein vp243, with the sequence of green fluorescent protein (GFP) was explored. A method combining TCID 50 and immunoperoxidase monolayer assay (IPMA) determined the most feasible locus for gene replacement to be pvp2. The genomic segment containing gfp at the pvp2 locus was able to be encapsidated into IBDV particles. Furthermore, the expression of GFP in GFP-IBDV infected cells was confirmed by Western blotting and GFP-IBDV particles showed similar morphology and size to that of wildtype IBDV by electron microscopy. By providing the deleted protein in trans in a packaging cell line (pVP2-DF1), replication-incompetent GFP-IBDV particles were successfully plaque-quantified. The gfp sequence from the plaque-forming GFP-IBDV in pVP2-DF1 was confirmed by RT-PCR and sequencing. To our knowledge, GFP-IBDV developed in the present study is the first replication-incompetent IBDV vector which expresses a foreign protein in infected cells without the capability to produce viral progeny. Additionally, such replication-incompetent IBDV vectors could serve as bivalent vaccine vectors for conferring protection against infections with IBDV and other economically important, or zoonotic, avian pathogens.

  4. Hepatitis B virus modulates store-operated calcium entry to enhance viral replication in primary hepatocytes.

    Directory of Open Access Journals (Sweden)

    Jessica C Casciano

    Full Text Available Many viruses modulate calcium (Ca2+ signaling to create a cellular environment that is more permissive to viral replication, but for most viruses that regulate Ca2+ signaling, the mechanism underlying this regulation is not well understood. The hepatitis B virus (HBV HBx protein modulates cytosolic Ca2+ levels to stimulate HBV replication in some liver cell lines. A chronic HBV infection is associated with life-threatening liver diseases, including hepatocellular carcinoma (HCC, and HBx modulation of cytosolic Ca2+ levels could have an important role in HBV pathogenesis. Whether HBx affects cytosolic Ca2+ in a normal hepatocyte, the natural site of an HBV infection, has not been addressed. Here, we report that HBx alters cytosolic Ca2+ signaling in cultured primary hepatocytes. We used single cell Ca2+ imaging of cultured primary rat hepatocytes to demonstrate that HBx elevates the cytosolic Ca2+ level in hepatocytes following an IP3-linked Ca2+ response; HBx effects were similar when expressed alone or in the context of replicating HBV. HBx elevation of the cytosolic Ca2+ level required extracellular Ca2+ influx and store-operated Ca2+ (SOC entry and stimulated HBV replication in hepatocytes. We used both targeted RT-qPCR and transcriptome-wide RNAseq analyses to compare levels of SOC channel components and other Ca2+ signaling regulators in HBV-expressing and control hepatocytes and show that the transcript levels of these various proteins are not affected by HBV. We also show that HBx regulation of SOC-regulated Ca2+ accumulation is likely the consequence of HBV modulation of a SOC channel regulatory mechanism. In support of this, we link HBx enhancement of SOC-regulated Ca2+ accumulation to Ca2+ uptake by mitochondria and demonstrate that HBx stimulates mitochondrial Ca2+ uptake in primary hepatocytes. The results of our study may provide insights into viral mechanisms that affect Ca2+ signaling to regulate viral replication and virus

  5. HIV-Specific CD8+ T Cell-Mediated Viral Suppression Correlates With the Expression of CD57

    DEFF Research Database (Denmark)

    Jensen, Sanne S; Tingstedt, Jeanette Linnea; Larsen, Tine Kochendorf

    2016-01-01

    BACKGROUND: Virus-specific CD8(+) T-cell responses are believed to play an important role in the control of HIV-1 infection; however, what constitutes an effective HIV-1 CD8(+) T-cell response remains a topic of debate. The ex vivo viral suppressive capacity was measured of CD8(+) T cells from 44...... HIV-1-positive individuals. The phenotypic and cytokine profiles, and also the specificity of the CD8(+) T cells, were correlated with the suppression of HIV-1 replication. We also aimed to determine whether antiretroviral therapy (ART) had any positive effect on the HIV-1 suppressive CD8(+) T cells....... METHOD: Ex vivo suppression assay was used to evaluate the ability of CD8(+) T cells to suppress HIV-1 replication in autologous CD4(+) T cells. The CD107a, interferon-γ, interleukin-2, tumor necrosis factor-α (TNF-α), and macrophage inflammatory protein-1β (MIP-1β) responses to HIV-1 were evaluated...

  6. Leukoencephalitis associated with selective viral replication in the brain of a pony with experimental chronic equine infectious anemia virus infection.

    Science.gov (United States)

    Oaks, J L; Long, M T; Baszler, T V

    2004-09-01

    Neurologic disease occurs sporadically in horses infected with the equine infectious anemia virus (EIAV). This report describes a case of clinically severe neurologic disease in a pony experimentally infected with EIAV. This pony did not have fever or anemia, which are the characteristic clinical signs of disease. The histopathologic changes were characterized as lymphohistiocytic periventricular leukoencephalitis. Polymerase chain reaction and in situ hybridization data showed that the brain lesions were directly associated with viral replication and that high-level viral replication occurred selectively within the lesion and not in other tissues. These findings suggest that EIAV-associated neurologic disease is the direct result of viral replication.

  7. Factors Associated With the Control of Viral Replication and Virologic Breakthrough in a Recently Infected HIV-1 Controller.

    Science.gov (United States)

    Walker-Sperling, Victoria E; Pohlmeyer, Christopher W; Veenhuis, Rebecca T; May, Megan; Luna, Krystle A; Kirkpatrick, Allison R; Laeyendecker, Oliver; Cox, Andrea L; Carrington, Mary; Bailey, Justin R; Arduino, Roberto C; Blankson, Joel N

    2017-02-01

    HIV-1 controllers are patients who control HIV-1 viral replication without antiretroviral therapy. Control is achieved very early in the course of infection, but the mechanisms through which viral replication is restricted are not fully understood. We describe a patient who presented with acute HIV-1 infection and was found to have an HIV-1 RNA level of controlled in acute HIV-1 infection in some patients without protective HLA alleles and that NK cell responses may contribute to this early control of viral replication. © 2016.

  8. Honeysuckle aqueous extract and induced let-7a suppress dengue virus type 2 replication and pathogenesis.

    Science.gov (United States)

    Lee, Ying-Ray; Yeh, Siao-Fen; Ruan, Xiao-Ming; Zhang, Hao; Hsu, Sheng-Da; Huang, Hsien-Da; Hsieh, Chang-Chi; Lin, Yee-Shin; Yeh, Trai-Ming; Liu, Hsiao-Sheng; Gan, Dai-Di

    2017-02-23

    Honeysuckle (Lonicera japonica Thunb.), a traditional Chinese herb, has widely been used to treat pathogen infection. However, the underlying-mechanism remains elusive. To reveal the host microRNA (miRNA) profile with the anti-viral activity after honeysuckle treatment. Here we reveal the differentially expressed miRNAs by Solexa ® deep sequencing from the blood of human and mice after the aqueous extract treatment. Among these overexpressed innate miRNAs both in human and mice, let-7a is able to target the NS1 region (nt 3313-3330) of dengue virus (DENV) serotypes 1, 2 and 4 predicated by the target predication software. We confirmed that let-7a could target DENV2 at the predicated NS1 sequence and suppress DENV2 replication demonstrated by luciferase-reporter activity, RT-PCR, real-time PCR, Western blotting and plaque assay. ICR-suckling mice consumed honeysuckle aqueous extract either before or after intracranial injection with DENV2 showed decreased levels of NS1 RNA and protein expression accompanied with alleviated disease symptoms, decreased virus load, and prolonged survival time. Similar results were observed when DENV2-infected mice were intracranially injected with let-7a. We reveal that honeysuckle attenuates DENV replication and related pathogenesis in vivo through induction of let-7a expression. This study opens a new direction for prevention and treatment of DENV infection through induction of the innate miRNA let-7a by honeysuckle. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  9. Novel elvitegravir nanoformulation approach to suppress the viral load in HIV-infected macrophages

    Directory of Open Access Journals (Sweden)

    Yuqing Gong

    2017-12-01

    Conclusions: PLGA-based EVG nanoformulation increased the intracellular uptake of EVG, as well as enhanced viral suppression in HIV-infected macrophages, suggesting its potential for improved HIV treatment in monocytic cells.

  10. Suppression of feline coronavirus replication in vitro by cyclosporin A

    Directory of Open Access Journals (Sweden)

    Tanaka Yoshikazu

    2012-04-01

    Full Text Available Abstract The feline infectious peritonitis virus (FIPV is a member of the feline coronavirus family that causes FIP, which is incurable and fatal in cats. Cyclosporin A (CsA, an immunosuppressive agent that targets the nuclear factor pathway of activated T-cells (NF-AT to bind cellular cyclophilins (CyP, dose-dependently inhibited FIPV replication in vitro. FK506 (an immunosuppressor of the pathway that binds cellular FK506-binding protein (FKBP but not CyP did not affect FIPV replication. Neither cell growth nor viability changed in the presence of either CsA or FK506, and these factors did not affect the NF-AT pathway in fcwf-4 cells. Therefore, CsA does not seem to exert inhibitory effects via the NF-AT pathway. In conclusion, CsA inhibited FIPV replication in vitro and further studies are needed to verify the practical value of CsA as an anti-FIPV treatment in vivo.

  11. Borna disease virus phosphoprotein modulates epigenetic signaling in neurons to control viral replication.

    Science.gov (United States)

    Bonnaud, Emilie M; Szelechowski, Marion; Bétourné, Alexandre; Foret, Charlotte; Thouard, Anne; Gonzalez-Dunia, Daniel; Malnou, Cécile E

    2015-06-01

    Understanding the modalities of interaction of neurotropic viruses with their target cells represents a major challenge that may improve our knowledge of many human neurological disorders for which viral origin is suspected. Borna disease virus (BDV) represents an ideal model to analyze the molecular mechanisms of viral persistence in neurons and its consequences for neuronal homeostasis. It is now established that BDV ensures its long-term maintenance in infected cells through a stable interaction of viral components with the host cell chromatin, in particular, with core histones. This has led to our hypothesis that such an interaction may trigger epigenetic changes in the host cell. Here, we focused on histone acetylation, which plays key roles in epigenetic regulation of gene expression, notably for neurons. We performed a comparative analysis of histone acetylation patterns of neurons infected or not infected by BDV, which revealed that infection decreases histone acetylation on selected lysine residues. We showed that the BDV phosphoprotein (P) is responsible for these perturbations, even when it is expressed alone independently of the viral context, and that this action depends on its phosphorylation by protein kinase C. We also demonstrated that BDV P inhibits cellular histone acetyltransferase activities. Finally, by pharmacologically manipulating cellular acetylation levels, we observed that inhibiting cellular acetyl transferases reduces viral replication in cell culture. Our findings reveal that manipulation of cellular epigenetics by BDV could be a means to modulate viral replication and thus illustrate a fascinating example of virus-host cell interaction. Persistent DNA viruses often subvert the mechanisms that regulate cellular chromatin dynamics, thereby benefitting from the resulting epigenetic changes to create a favorable milieu for their latent and persistent states. Here, we reasoned that Borna disease virus (BDV), the only RNA virus known to

  12. Human cytomegalovirus RL13 protein interacts with host NUDT14 protein affecting viral DNA replication.

    Science.gov (United States)

    Wang, Guili; Ren, Gaowei; Cui, Xin; Lu, Zhitao; Ma, Yanping; Qi, Ying; Huang, Yujing; Liu, Zhongyang; Sun, Zhengrong; Ruan, Qiang

    2016-03-01

    The interaction between the host and human cytomegalovirus (HCMV) is important in determining the outcome of a viral infection. The HCMV RL13 gene product exerts independent, inhibitory effects on viral growth in fibroblasts and epithelial cells. At present, there are few reports on the interactions between the HCMV RL13 protein and human host proteins. The present study provided direct evidence for the specific interaction between HCMV RL13 and host nucleoside diphosphate linked moiety X (nudix)‑type motif 14 (NUDT14), a UDP‑glucose pyrophosphatase, using two‑hybrid screening, an in vitro glutathione S‑transferase pull‑down assay, and co‑immunoprecipitation in human embryonic kidney HEK293 cells. Additionally, the RL13 protein was shown to co‑localize with the NUDT14 protein in the HEK293 cell membrane and cytoplasm, demonstrated using fluorescence confocal microscopy. Decreasing the expression level of NUDT14 via NUDT14‑specific small interfering RNAs increased the number of viral DNA copies in the HCMV‑infected cells. However, the overexpression of NUDT14 in a stably expressing cell line did not affect viral DNA levels significantly in the HCMV infected cells. Based on the known functions of NUDT14, the results of the present study suggested that the interaction between the RL13 protein and NUDT14 protein may be involved in HCMV DNA replication, and that NUDT14 may offer potential in the modulation of viral infection.

  13. The population impact of eliminating homelessness on HIV viral suppression among people who use drugs.

    Science.gov (United States)

    Marshall, Brandon D L; Elston, Beth; Dobrer, Sabina; Parashar, Surita; Hogg, Robert S; Montaner, Julio S G; Kerr, Thomas; Wood, Evan; Milloy, M-J

    2016-03-27

    We sought to estimate the change in viral suppression prevalence if homelessness were eliminated from a population of HIV-infected people who use drugs. Community-recruited prospective cohort of HIV-infected people who use drugs in Vancouver, Canada. Behavioural information was collected at baseline and linked to a province-wide HIV/AIDS treatment database. The primary outcome was viral suppression (homelessness and viral suppression (adjusting for sociodemographics, substance use, addiction treatment, and other confounders). Then, we imputed an outcome probability for each individual while manipulating the exposure (homelessness). Population viral suppression prevalence under realized and 'housed' scenarios were obtained by averaging these probabilities across the study population. Bootstrapping was conducted to calculate 95% confidence limits. Of 706 individuals interviewed between January 2005 and December 2013, the majority were men (66.0%), of white race/ethnicity (55.1%), and had a history of injection drug use (93.6%). At first study visit, 223 (31.6%) reported recent homelessness, and 37.8% were subsequently identified as virally suppressed. Adjusted marginal models estimated a 15.1% relative increase [95% confidence interval (CI) 9.0-21.7%) in viral suppression in the entire population - to 43.5% (95% CI 39.4-48.2%) - if all homeless individuals were housed. Among those homeless, eliminating this exposure would increase viral suppression from 22.0 to 40.1% (95% CI 35.1-46.1%), an 82.3% relative increase. Interventions to house homeless, HIV-positive individuals who use drugs could significantly increase population viral suppression. Such interventions should be implemented as a part of renewed HIV/AIDS prevention and treatment efforts.

  14. SV40 utilizes ATM kinase activity to prevent non-homologous end joining of broken viral DNA replication products.

    Science.gov (United States)

    Sowd, Gregory A; Mody, Dviti; Eggold, Joshua; Cortez, David; Friedman, Katherine L; Fanning, Ellen

    2014-12-01

    Simian virus 40 (SV40) and cellular DNA replication rely on host ATM and ATR DNA damage signaling kinases to facilitate DNA repair and elicit cell cycle arrest following DNA damage. During SV40 DNA replication, ATM kinase activity prevents concatemerization of the viral genome whereas ATR activity prevents accumulation of aberrant genomes resulting from breakage of a moving replication fork as it converges with a stalled fork. However, the repair pathways that ATM and ATR orchestrate to prevent these aberrant SV40 DNA replication products are unclear. Using two-dimensional gel electrophoresis and Southern blotting, we show that ATR kinase activity, but not DNA-PK(cs) kinase activity, facilitates some aspects of double strand break (DSB) repair when ATM is inhibited during SV40 infection. To clarify which repair factors associate with viral DNA replication centers, we examined the localization of DSB repair proteins in response to SV40 infection. Under normal conditions, viral replication centers exclusively associate with homology-directed repair (HDR) and do not colocalize with non-homologous end joining (NHEJ) factors. Following ATM inhibition, but not ATR inhibition, activated DNA-PK(cs) and KU70/80 accumulate at the viral replication centers while CtIP and BLM, proteins that initiate 5' to 3' end resection during HDR, become undetectable. Similar to what has been observed during cellular DSB repair in S phase, these data suggest that ATM kinase influences DSB repair pathway choice by preventing the recruitment of NHEJ factors to replicating viral DNA. These data may explain how ATM prevents concatemerization of the viral genome and promotes viral propagation. We suggest that inhibitors of DNA damage signaling and DNA repair could be used during infection to disrupt productive viral DNA replication.

  15. A DNA Binding Protein Is Required for Viral Replication and Transcription in Bombyx mori Nucleopolyhedrovirus.

    Science.gov (United States)

    Zhao, Cui; Zhang, Chen; Chen, Bin; Shi, Yanghui; Quan, Yanping; Nie, Zuoming; Zhang, Yaozhou; Yu, Wei

    2016-01-01

    A DNA-binding protein (DBP) [GenBank accession number: M63416] of Bombyx mori nuclear polyhedrosis virus (BmNPV) has been reported to be a regulatory factor in BmNPV, but its detailed functions remain unknown. In order to study the regulatory mechanism of DBP on viral proliferation, genome replication, and gene transcription, a BmNPV dbp gene knockout virus dbp-ko-Bacmid was generated by the means of Red recombination system. In addition, dbp-repaired virus dbp-re-Bacmid was constructed by the means of the Bac to Bac system. Then, the Bacmids were transfected into BmN cells. The results of this viral titer experiment revealed that the TCID50 of the dbp-ko-Bacmid was 0; however, the dbp-re-Bacmid was similar to the wtBacmid (p>0.05), indicating that the dbp-deficient would lead to failure in the assembly of virus particles. In the next step, Real-Time PCR was used to analyze the transcriptional phases of dbp gene in BmN cells, which had been infected with BmNPV. The results of the latter experiment revealed that the transcript of dbp gene was first detected at 3 h post-infection. Furthermore, the replication level of virus genome and the transcriptional level of virus early, late, and very late genes in BmN cells, which had been transfected with 3 kinds of Bacmids, were analyzed by Real-Time PCR. The demonstrating that the replication level of genome was lower than that of wtBacmid and dbp-re-Bacmid (pviral replication, but also a viral gene that has a significant impact on transcription and expression during all periods of baculovirus life cycle.

  16. CRISPR/Cas9-Derived Mutations Both Inhibit HIV-1 Replication and Accelerate Viral Escape

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    2016-04-01

    Full Text Available Cas9 cleaves specific DNA sequences with the assistance of a programmable single guide RNA (sgRNA. Repairing this broken DNA by the cell’s error-prone non-homologous end joining (NHEJ machinery leads to insertions and deletions (indels that often impair DNA function. Using HIV-1, we have now demonstrated that many of these indels are indeed lethal for the virus, but that others lead to the emergence of replication competent viruses that are resistant to Cas9/sgRNA. This unexpected contribution of Cas9 to the development of viral resistance is facilitated by some indels that are not deleterious for viral replication, but that are refractory to recognition by the same sgRNA as a result of changing the target DNA sequences. This observation illustrates two opposite outcomes of Cas9/sgRNA action, i.e., inactivation of HIV-1 and acceleration of viral escape, thereby potentially limiting the use of Cas9/sgRNA in HIV-1 therapy.

  17. Viral terminal protein directs early organization of phage DNA replication at the bacterial nucleoid.

    Science.gov (United States)

    Muñoz-Espín, Daniel; Holguera, Isabel; Ballesteros-Plaza, David; Carballido-López, Rut; Salas, Margarita

    2010-09-21

    The mechanism leading to protein-primed DNA replication has been studied extensively in vitro. However, little is known about the in vivo organization of the proteins involved in this fundamental process. Here we show that the terminal proteins (TPs) of phages ϕ29 and PRD1, infecting the distantly related bacteria Bacillus subtilis and Escherichia coli, respectively, associate with the host bacterial nucleoid independently of other viral-encoded proteins. Analyses of phage ϕ29 revealed that the TP N-terminal domain (residues 1-73) possesses sequence-independent DNA-binding capacity and is responsible for its nucleoid association. Importantly, we show that in the absence of the TP N-terminal domain the efficiency of ϕ29 DNA replication is severely affected. Moreover, the TP recruits the phage DNA polymerase to the bacterial nucleoid, and both proteins later are redistributed to enlarged helix-like structures in an MreB cytoskeleton-dependent way. These data disclose a key function for the TP in vivo: organizing the early viral DNA replication machinery at the cell nucleoid.

  18. A prophage-encoded actin-like protein required for efficient viral DNA replication in bacteria.

    Science.gov (United States)

    Donovan, Catriona; Heyer, Antonia; Pfeifer, Eugen; Polen, Tino; Wittmann, Anja; Krämer, Reinhard; Frunzke, Julia; Bramkamp, Marc

    2015-05-26

    In host cells, viral replication is localized at specific subcellular sites. Viruses that infect eukaryotic and prokaryotic cells often use host-derived cytoskeletal structures, such as the actin skeleton, for intracellular positioning. Here, we describe that a prophage, CGP3, integrated into the genome of Corynebacterium glutamicum encodes an actin-like protein, AlpC. Biochemical characterization confirms that AlpC is a bona fide actin-like protein and cell biological analysis shows that AlpC forms filamentous structures upon prophage induction. The co-transcribed adaptor protein, AlpA, binds to a consensus sequence in the upstream promoter region of the alpAC operon and also interacts with AlpC, thus connecting circular phage DNA to the actin-like filaments. Transcriptome analysis revealed that alpA and alpC are among the early induced genes upon excision of the CGP3 prophage. Furthermore, qPCR analysis of mutant strains revealed that both AlpA and AlpC are required for efficient phage replication. Altogether, these data emphasize that AlpAC are crucial for the spatio-temporal organization of efficient viral replication. This is remarkably similar to actin-assisted membrane localization of eukaryotic viruses that use the actin cytoskeleton to concentrate virus particles at the egress sites and provides a link of evolutionary conserved interactions between intracellular virus transport and actin. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  19. Leflunomide/teriflunomide inhibit Epstein-Barr virus (EBV)- induced lymphoproliferative disease and lytic viral replication.

    Science.gov (United States)

    Bilger, Andrea; Plowshay, Julie; Ma, Shidong; Nawandar, Dhananjay; Barlow, Elizabeth A; Romero-Masters, James C; Bristol, Jillian A; Li, Zhe; Tsai, Ming-Han; Delecluse, Henri-Jacques; Kenney, Shannon C

    2017-07-04

    EBV infection causes mononucleosis and is associated with specific subsets of B cell lymphomas. Immunosuppressed patients such as organ transplant recipients are particularly susceptible to EBV-induced lymphoproliferative disease (LPD), which can be fatal. Leflunomide (a drug used to treat rheumatoid arthritis) and its active metabolite teriflunomide (used to treat multiple sclerosis) inhibit de novo pyrimidine synthesis by targeting the cellular dihydroorotate dehydrogenase, thereby decreasing T cell proliferation. Leflunomide also inhibits the replication of cytomegalovirus and BK virus via both "on target" and "off target" mechanisms and is increasingly used to treat these viruses in organ transplant recipients. However, whether leflunomide/teriflunomide block EBV replication or inhibit EBV-mediated B cell transformation is currently unknown. We show that teriflunomide inhibits cellular proliferation, and promotes apoptosis, in EBV-transformed B cells in vitro at a clinically relevant dose. In addition, teriflunomide prevents the development of EBV-induced lymphomas in both a humanized mouse model and a xenograft model. Furthermore, teriflunomide inhibits lytic EBV infection in vitro both by preventing the initial steps of lytic viral reactivation, and by blocking lytic viral DNA replication. Leflunomide/teriflunomide might therefore be clinically useful for preventing EBV-induced LPD in patients who have high EBV loads yet require continued immunosuppression.

  20. miR-370 suppresses HBV gene expression and replication by targeting nuclear factor IA.

    Science.gov (United States)

    Fan, Hongxia; Lv, Ping; Lv, Jing; Zhao, Xiaopei; Liu, Min; Zhang, Guangling; Tang, Hua

    2017-05-01

    Hepatitis B virus (HBV) infection is a major health problem worldwide. The roles of microRNAs in the regulation of HBV expression are being increasingly recognized. In this study, we found that overexpression of miR-370 suppressed HBV gene expression and replication in Huh7 cells, whereas antisense knockdown of endogenous miR-370 enhanced HBV gene expression and replication in Huh7 cells and HepG2.2.15 cells. Further, we identified the transcription factor nuclear factor IA (NFIA) as a new host target of miR-370. Overexpression and knockdown studies showed that NFIA stimulated HBV gene expression and replication. Importantly, overexpression of NFIA counteracted the effect of miR-370 on HBV gene expression and replication. Further mechanistic studies showed that miR-370 suppressed HBV replication and gene expression by repressing HBV Enhancer I activity, and one of the NFIA binding site in the Enhancer I element was responsible for the repressive effect of miR-370 on HBV Enhancer I activity. Altogether, our results demonstrated that miR-370 suppressed HBV gene expression and replication through repressing NFIA expression, which stimulates HBV replication via direct regulation on HBV Enhancer I activities. Our findings may provide a new antiviral strategy for HBV infection. J. Med. Virol. 89:834-844, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  1. Transforming growth factor-β1 suppresses hepatitis B virus replication by the reduction of hepatocyte nuclear factor-4α expression.

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    Ming-Hsiang Hong

    Full Text Available Several studies have demonstrated that cytokine-mediated noncytopathic suppression of hepatitis B virus (HBV replication may provide an alternative therapeutic strategy for the treatment of chronic hepatitis B infection. In our previous study, we showed that transforming growth factor-beta1 (TGF-β1 could effectively suppress HBV replication at physiological concentrations. Here, we provide more evidence that TGF-β1 specifically diminishes HBV core promoter activity, which subsequently results in a reduction in the level of viral pregenomic RNA (pgRNA, core protein (HBc, nucleocapsid, and consequently suppresses HBV replication. The hepatocyte nuclear factor 4alpha (HNF-4α binding element(s within the HBV core promoter region was characterized to be responsive for the inhibitory effect of TGF-β1 on HBV regulation. Furthermore, we found that TGF-β1 treatment significantly repressed HNF-4α expression at both mRNA and protein levels. We demonstrated that RNAi-mediated depletion of HNF-4α was sufficient to reduce HBc synthesis as TGF-β1 did. Prevention of HNF-4α degradation by treating with proteasome inhibitor MG132 also prevented the inhibitory effect of TGF-β1. Finally, we confirmed that HBV replication could be rescued by ectopic expression of HNF-4α in TGF-β1-treated cells. Our data clarify the mechanism by which TGF-β1 suppresses HBV replication, primarily through modulating the expression of HNF-4α gene.

  2. THE POPULATION IMPACT OF ELIMINATING HOMELESSNESS ON HIV VIRAL SUPPRESSION AMONG PEOPLE WHO USE DRUGS

    Science.gov (United States)

    Marshall, Brandon D.L.; Elston, Beth; Dobrer, Sabina; Parashar, Surita; Hogg, Robert S.; Montaner, Julio S.G.; Kerr, Thomas; Wood, Evan; Milloy, M-J

    2015-01-01

    Objective We sought to estimate the change in viral suppression prevalence if homelessness were eliminated from a population of HIV-infected people who use drugs (PWUD). Design Community-recruited prospective cohort of HIV-infected PWUD in Vancouver, Canada. Behavioral information was collected at baseline and linked to a province-wide HIV/AIDS treatment database. The primary outcome was viral suppression (<50 copies/mL) measured during subsequent routine clinical care. Methods We employed an imputation-based marginal modelling approach. First, we used modified Poisson regression to obtain effect estimates (adjusting for sociodemographics, substance use, addiction treatment, and other confounders). Then, we imputed an outcome probability for each individual while manipulating the exposure (homelessness). Population viral suppression prevalence under realized and “housed” scenarios were obtained by averaging these probabilities across the population. Bootstrapping was conducted to calculate 95% confidence limits. Results Of 706 individuals interviewed between January 2005 and December 2015, the majority was male (66.0%), of Caucasian race/ethnicity (55.1%), and had a history of injection (93.6%). At first study visit, 223 (31.6%) reported recent homelessness, and 37.8% were subsequently identified as virally suppressed. Adjusted marginal models estimated a 15.1% relative increase (95%CI: 9.0%, 21.7%) in viral suppression in the entire population—to 43.5% (95%CI: 39.4%, 48.2%)—if all homeless individuals were housed. Among those homeless, eliminating this exposure would increase viral suppression from 22.0% to 40.1% (95%CI: 35.1%, 46.1%), an 82.3% relative increase. Conclusions Interventions to house homeless, HIV-positive individuals who use drugs could significantly increase population viral suppression. Such interventions should be implemented as a part of renewed HIV/AIDS prevention and treatment efforts. PMID:26636924

  3. Plasmacytoid dendritic cells suppress HIV-1 replication but contribute to HIV-1 induced immunopathogenesis in humanized mice.

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    Guangming Li

    2014-07-01

    Full Text Available The role of plasmacytoid dendritic cells (pDC in human immunodeficiency virus type 1 (HIV-1 infection and pathogenesis remains unclear. HIV-1 infection in the humanized mouse model leads to persistent HIV-1 infection and immunopathogenesis, including type I interferons (IFN-I induction, immune-activation and depletion of human leukocytes, including CD4 T cells. We developed a monoclonal antibody that specifically depletes human pDC in all lymphoid organs in humanized mice. When pDC were depleted prior to HIV-1 infection, the induction of IFN-I and interferon-stimulated genes (ISGs were abolished during acute HIV-1 infection with either a highly pathogenic CCR5/CXCR4-dual tropic HIV-1 or a standard CCR5-tropic HIV-1 isolate. Consistent with the anti-viral role of IFN-I, HIV-1 replication was significantly up-regulated in pDC-depleted mice. Interestingly, the cell death induced by the highly pathogenic HIV-1 isolate was severely reduced in pDC-depleted mice. During chronic HIV-1 infection, depletion of pDC also severely reduced the induction of IFN-I and ISGs, associated with elevated HIV-1 replication. Surprisingly, HIV-1 induced depletion of human immune cells including T cells in lymphoid organs, but not the blood, was reduced in spite of the increased viral replication. The increased cell number in lymphoid organs was associated with a reduced level of HIV-induced cell death in human leukocytes including CD4 T cells. We conclude that pDC play opposing roles in suppressing HIV-1 replication and in promoting HIV-1 induced immunopathogenesis. These findings suggest that pDC-depletion and IFN-I blockade will provide novel strategies for treating those HIV-1 immune non-responsive patients with persistent immune activation despite effective anti-retrovirus treatment.

  4. Cytoplasmic translocation of polypyrimidine tract-binding protein and its binding to viral RNA during Japanese encephalitis virus infection inhibits virus replication.

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    Deepika Bhullar

    Full Text Available Japanese encephalitis virus (JEV has a single-stranded, positive-sense RNA genome containing a single open reading frame flanked by the 5'- and 3'-non-coding regions (NCRs. The virus genome replicates via a negative-sense RNA intermediate. The NCRs and their complementary sequences in the negative-sense RNA are the sites for assembly of the RNA replicase complex thereby regulating the RNA synthesis and virus replication. In this study, we show that the 55-kDa polypyrimidine tract-binding protein (PTB interacts in vitro with both the 5'-NCR of the positive-sense genomic RNA--5NCR(+, and its complementary sequence in the negative-sense replication intermediate RNA--3NCR(-. The interaction of viral RNA with PTB was validated in infected cells by JEV RNA co-immunoprecipitation and JEV RNA-PTB colocalization experiments. Interestingly, we observed phosphorylation-coupled translocation of nuclear PTB to cytoplasmic foci that co-localized with JEV RNA early during JEV infection. Our studies employing the PTB silencing and over-expression in cultured cells established an inhibitory role of PTB in JEV replication. Using RNA-protein binding assay we show that PTB competitively inhibits association of JEV 3NCR(- RNA with viral RNA-dependent RNA polymerase (NS5 protein, an event required for the synthesis of the plus-sense genomic RNA. cAMP is known to promote the Protein kinase A (PKA-mediated PTB phosphorylation. We show that cells treated with a cAMP analogue had an enhanced level of phosphorylated PTB in the cytoplasm and a significantly suppressed JEV replication. Data presented here show a novel, cAMP-induced, PTB-mediated, innate host response that could effectively suppress JEV replication in mammalian cells.

  5. The bovine papilloma virus E1 protein has ATPase activity essential to viral DNA replication and efficient transformation in cells.

    Science.gov (United States)

    MacPherson, P; Thorner, L; Parker, L M; Botchan, M

    1994-10-01

    The bovine papilloma virus (BPV) E1 protein essential to viral DNA replication has recently been shown to associate via direct protein-DNA interactions with the viral origin of replication and to be an ATP-dependent helicase. We show here that in accordance with the latter function, the E1 gene product has intrinsic ATPase activity. Mutations placed throughout the nucleotide binding consensus element abolish the ATPase activity of E1 and render BPV genomes harboring such mutations defective for episomal replication and impaired for oncogenic transformation.

  6. Molecular and functional analysis of a conserved CTL epitope in HIV-1 p24 recognized from a long-term nonprogressor: constraints on immune escape associated with targeting a sequence essential for viral replication.

    Science.gov (United States)

    Wagner, R; Leschonsky, B; Harrer, E; Paulus, C; Weber, C; Walker, B D; Buchbinder, S; Wolf, H; Kalden, J R; Harrer, T

    1999-03-15

    It has been hypothesized that sequence variation within CTL epitopes leading to immune escape plays a role in the progression of HIV-1 infection. Only very limited data exist that address the influence of biologic characteristics of CTL epitopes on the emergence of immune escape variants and the efficiency of suppression HIV-1 by CTL. In this report, we studied the effects of HIV-1 CTL epitope sequence variation on HIV-1 replication. The highly conserved HLA-B14-restricted CTL epitope DRFYKTLRAE in HIV-1 p24 was examined, which had been defined as the immunodominant CTL epitope in a long-term nonprogressing individual. We generated a set of viral mutants on an HX10 background differing by a single conservative or nonconservative amino acid substitution at each of the P1 to P9 amino acid residues of the epitope. All of the nonconservative amino acid substitutions abolished viral infectivity and only 5 of 10 conservative changes yielded replication-competent virus. Recognition of these epitope sequence variants by CTL was tested using synthetic peptides. All mutations that abrogated CTL recognition strongly impaired viral replication, and all replication-competent viral variants were recognized by CTL, although some variants with a lower efficiency. Our data indicate that this CTL epitope is located within a viral sequence essential for viral replication. Targeting CTL epitopes within functionally important regions of the HIV-1 genome could limit the chance of immune evasion.

  7. Paucity and preferential suppression of transgenes in late replication domains of the D. melanogaster genome.

    Science.gov (United States)

    Babenko, Vladimir N; Makunin, Igor V; Brusentsova, Irina V; Belyaeva, Elena S; Maksimov, Daniil A; Belyakin, Stepan N; Maroy, Peter; Vasil'eva, Lyubov A; Zhimulev, Igor F

    2010-05-21

    Eukaryotic genomes are organized in extended domains with distinct features intimately linking genome structure, replication pattern and chromatin state. Recently we identified a set of long late replicating euchromatic regions that are underreplicated in salivary gland polytene chromosomes of D. melanogaster. Here we demonstrate that these underreplicated regions (URs) have a low density of P-element and piggyBac insertions compared to the genome average or neighboring regions. In contrast, Minos-based transposons show no paucity in URs but have a strong bias to testis-specific genes. We estimated the suppression level in 2,852 stocks carrying a single P-element by analysis of eye color determined by the mini-white marker gene and demonstrate that the proportion of suppressed transgenes in URs is more than three times higher than in the flanking regions or the genomic average. The suppressed transgenes reside in intergenic, genic or promoter regions of the annotated genes. We speculate that the low insertion frequency of P-elements and piggyBacs in URs partially results from suppression of transgenes that potentially could prevent identification of transgenes due to complete suppression of the marker gene. In a similar manner, the proportion of suppressed transgenes is higher in loci replicating late or very late in Kc cells and these loci have a lower density of P-elements and piggyBac insertions. In transgenes with two marker genes suppression of mini-white gene in eye coincides with suppression of yellow gene in bristles. Our results suggest that the late replication domains have a high inactivation potential apparently linked to the silenced or closed chromatin state in these regions, and that such inactivation potential is largely maintained in different tissues.

  8. Phosphorylation of Human Metapneumovirus M2-1 Protein Upregulates Viral Replication and Pathogenesis.

    Science.gov (United States)

    Cai, Hui; Zhang, Yu; Lu, Mijia; Liang, Xueya; Jennings, Ryan; Niewiesk, Stefan; Li, Jianrong

    2016-08-15

    Human metapneumovirus (hMPV) is a major causative agent of upper- and lower-respiratory-tract infections in infants, the elderly, and immunocompromised individuals worldwide. Like all pneumoviruses, hMPV encodes the zinc binding protein M2-1, which plays important regulatory roles in RNA synthesis. The M2-1 protein is phosphorylated, but the specific role(s) of the phosphorylation in viral replication and pathogenesis remains unknown. In this study, we found that hMPV M2-1 is phosphorylated at amino acid residues S57 and S60. Subsequent mutagenesis found that phosphorylation is not essential for zinc binding activity and oligomerization, whereas inhibition of zinc binding activity abolished the phosphorylation and oligomerization of the M2-1 protein. Using a reverse genetics system, recombinant hMPVs (rhMPVs) lacking either one or both phosphorylation sites in the M2-1 protein were recovered. These recombinant viruses had a significant decrease in both genomic RNA replication and mRNA transcription. In addition, these recombinant viruses were highly attenuated in cell culture and cotton rats. Importantly, rhMPVs lacking phosphorylation in the M2-1 protein triggered high levels of neutralizing antibody and provided complete protection against challenge with wild-type hMPV. Collectively, these data demonstrated that phosphorylation of the M2-1 protein upregulates hMPV RNA synthesis, replication, and pathogenesis in vivo The pneumoviruses include many important human and animal pathogens, such as human respiratory syncytial virus (hRSV), hMPV, bovine RSV, and avian metapneumovirus (aMPV). Among these viruses, hRSV and hMPV are the leading causes of acute respiratory tract infection in infants and children. Currently, there is no antiviral or vaccine to combat these diseases. All known pneumoviruses encode a zinc binding protein, M2-1, which is a transcriptional antitermination factor. In this work, we found that phosphorylation of M2-1 is essential for virus

  9. Endemic versus epidemic viral spreads display distinct patterns of HTLV-2b replication

    International Nuclear Information System (INIS)

    Gabet, Anne-Sophie; Moules, Vincent; Sibon, David; Nass, Catharie C.; Mortreux, Franck; Mauclere, Philippe; Gessain, Antoine; Murphy, Edward L.; Wattel, Eric

    2006-01-01

    As the replication pattern of leukemogenic PTLVs possesses a strong pathogenic impact, we investigated HTLV-2 replication in vivo in asymptomatic carriers belonging into 2 distinct populations infected by the same HTLV-2b subtype. They include epidemically infected American blood donors, in whom HTLV-2b has been present for only 30 years, and endemically infected Bakola Pygmies from Cameroon, characterized by a long viral endemicity (at least few generations). In blood donors, both the circulating proviral loads and the degree of infected cell proliferation were largely lower than those characterizing asymptomatic carriers infected with leukemogenic PTLVs (HTLV-1, STLV-1). This might contribute to explain the lack of known link between HTLV-2b infection and the development of malignancies in this population. In contrast, endemically infected individuals displayed high proviral loads resulting from the extensive proliferation of infected cells. The route and/or the duration of infection, viral genetic drift, host immune response, genetic background, co-infections or a combination thereof might have contributed to these differences between endemically and epidemically infected subjects. As the clonality pattern observed in endemically infected individuals is very reminiscent of that of leukemogenic PTLVs at the pre-leukemic stage, our results highlight the possible oncogenic effect of HTLV-2b infection in such population

  10. Mutational analysis of the hypervariable region of hepatitis e virus reveals its involvement in the efficiency of viral RNA replication.

    Science.gov (United States)

    Pudupakam, R S; Kenney, Scott P; Córdoba, Laura; Huang, Yao-Wei; Dryman, Barbara A; Leroith, Tanya; Pierson, F William; Meng, Xiang-Jin

    2011-10-01

    The RNA genome of the hepatitis E virus (HEV) contains a hypervariable region (HVR) in ORF1 that tolerates small deletions with respect to infectivity. To further investigate the role of the HVR in HEV replication, we constructed a panel of mutants with overlapping deletions in the N-terminal, central, and C-terminal regions of the HVR by using a genotype 1 human HEV luciferase replicon and analyzed the effects of deletions on viral RNA replication in Huh7 cells. We found that the replication levels of the HVR deletion mutants were markedly reduced in Huh7 cells, suggesting a role of the HVR in viral replication efficiency. To further verify the results, we constructed HVR deletion mutants by using a genetically divergent, nonmammalian avian HEV, and similar effects on viral replication efficiency were observed when the avian HEV mutants were tested in LMH cells. Furthermore, the impact of complete HVR deletion on virus infectivity was tested in chickens, using an avian HEV mutant with a complete HVR deletion. Although the deletion mutant was still replication competent in LMH cells, the complete HVR deletion resulted in a loss of avian HEV infectivity in chickens. Since the HVR exhibits extensive variations in sequence and length among different HEV genotypes, we further examined the interchangeability of HVRs and demonstrated that HVR sequences are functionally exchangeable between HEV genotypes with regard to viral replication and infectivity in vitro, although genotype-specific HVR differences in replication efficiency were observed. The results showed that although the HVR tolerates small deletions with regard to infectivity, it may interact with viral and host factors to modulate the efficiency of HEV replication.

  11. Sulforaphane Suppresses Hepatitis C Virus Replication by Up-Regulating Heme Oxygenase-1 Expression through PI3K/Nrf2 Pathway.

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    Jung-Sheng Yu

    Full Text Available Hepatitis C virus (HCV infection-induced oxidative stress is a major risk factor for the development of HCV-associated liver disease. Sulforaphane (SFN is an antioxidant phytocompound that acts against cellular oxidative stress and tumorigenesis. However, there is little known about its anti-viral activity. In this study, we demonstrated that SFN significantly suppressed HCV protein and RNA levels in HCV replicon cells and infectious system, with an IC50 value of 5.7 ± 0.2 μM. Moreover, combination of SFN with anti-viral drugs displayed synergistic effects in the suppression of HCV replication. In addition, we found nuclear factor erythroid 2-related factor 2 (Nrf2/HO-1 induction in response to SFN and determined the signaling pathways involved in this process, including inhibition of NS3 protease activity and induction of IFN response. In contrast, the anti-viral activities were attenuated by knockdown of HO-1 with specific inhibitor (SnPP and shRNA, suggesting that anti-HCV activity of SFN is dependent on HO-1 expression. Otherwise, SFN stimulated the phosphorylation of phosphoinositide 3-kinase (PI3K leading Nrf2-mediated HO-1 expression against HCV replication. Overall, our results indicated that HO-1 is essential in SFN-mediated anti-HCV activity and provide new insights in the molecular mechanism of SFN in HCV replication.

  12. AR-12 suppresses dengue virus replication by down-regulation of PI3K/AKT and GRP78.

    Science.gov (United States)

    Chen, Hsin-Hsin; Chen, Chien-Chin; Lin, Yee-Shin; Chang, Po-Chun; Lu, Zi-Yi; Lin, Chiou-Feng; Chen, Chia-Ling; Chang, Chih-Peng

    2017-06-01

    Dengue virus (DENV) infection has become a public health issue of worldwide concern and is a serious health problem in Taiwan, yet there are no approved effective antiviral drugs to treat DENV. The replication of DENV requires both viral and cellular factors. Targeting host factors may provide a potential antiviral strategy. It has been known that up-regulation of PI3K/AKT signaling and GRP78 by DENV infection supports its replication. AR-12, a celecoxib derivative with no inhibiting activity on cyclooxygenase, shows potent inhibitory activities on both PI3K/AKT signaling and GRP78 expression levels, and recently has been found to block the replication of several hemorrhagic fever viruses. However the efficacy of AR-12 in treating DENV infection is still unclear. Here, we provide evidence to show that AR-12 is able to suppress DENV replication before or after virus infection in cell culture and mice. The antiviral activities of AR-12 are positive against infection of the four different DENV serotypes. AR-12 significantly down-regulates the PI3K/AKT activity and GRP78 expression in DENV infected cells whereas AKT and GRP78 rescue are able to attenuate anti-DENV effect of AR-12. Using a DENV-infected suckling mice model, we further demonstrate that treatment of AR-12 before or after DENV infection reduces virus replication and mice mortality. In conclusion, we uncover the potential efficacy of AR-12 as a novel drug for treating dengue. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. The logic of DNA replication in double-stranded DNA viruses: insights from global analysis of viral genomes.

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    Kazlauskas, Darius; Krupovic, Mart; Venclovas, Česlovas

    2016-06-02

    Genomic DNA replication is a complex process that involves multiple proteins. Cellular DNA replication systems are broadly classified into only two types, bacterial and archaeo-eukaryotic. In contrast, double-stranded (ds) DNA viruses feature a much broader diversity of DNA replication machineries. Viruses differ greatly in both completeness and composition of their sets of DNA replication proteins. In this study, we explored whether there are common patterns underlying this extreme diversity. We identified and analyzed all major functional groups of DNA replication proteins in all available proteomes of dsDNA viruses. Our results show that some proteins are common to viruses infecting all domains of life and likely represent components of the ancestral core set. These include B-family polymerases, SF3 helicases, archaeo-eukaryotic primases, clamps and clamp loaders of the archaeo-eukaryotic type, RNase H and ATP-dependent DNA ligases. We also discovered a clear correlation between genome size and self-sufficiency of viral DNA replication, the unanticipated dominance of replicative helicases and pervasive functional associations among certain groups of DNA replication proteins. Altogether, our results provide a comprehensive view on the diversity and evolution of replication systems in the DNA virome and uncover fundamental principles underlying the orchestration of viral DNA replication. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  14. Suppression of gross chromosomal rearrangements by a new alternative replication factor C complex

    International Nuclear Information System (INIS)

    Banerjee, Soma; Sikdar, Nilabja; Myung, Kyungjae

    2007-01-01

    Defects in DNA replication fidelity lead to genomic instability. Gross chromosomal rearrangement (GCR), a type of genomic instability, is highly enhanced by various initial mutations affecting DNA replication. Frequent observations of GCRs in many cancers strongly argue the importance of maintaining high fidelity of DNA replication to suppress carcinogenesis. Recent genome wide screens in Saccharomyces cerevisiae identified a new GCR suppressor gene, ELG1, enhanced level of genome instability gene 1. Its physical interaction with proliferating cell nuclear antigen (PCNA) and complex formation with Rfc2-5p proteins suggest that Elg1 functions to load/unload PCNA onto DNA during a certain DNA metabolism. High level of DNA damage accumulation and enhanced phenotypes with mutations in genes involved in cell cycle checkpoints, homologous recombination (HR), or chromatin assembly in the elg1 strain suggest that Elg1p-Rfc2-5p functions in a fundamental DNA metabolism to suppress genomic instability

  15. The bovine papillomavirus constitutive enhancer is essential for viral transformation, DNA replication, and the maintenance of latency.

    Science.gov (United States)

    Vande Pol, S B; Howley, P M

    1992-04-01

    Bovine papillomavirus type 1 (BPV-1) has served as the prototype papillomavirus for the study of viral transcription, DNA replication, and latency. However, no cis essential transcription control regions which are necessary for both transformation and replication of BPV-1 or any other papillomavirus have yet been defined. We have found that BPV-1 mutants with deletions in the long control region were defective for transformation and replication, with the essential region in the 5' long control region corresponding to the previously defined BPV-1 constitutive enhancer (S. B. Vande Pol and P. M. Howley, J. Virol. 64:5420-5429, 1990). BPV-1 mutants deleted of the constitutive enhancer could be complemented in trans by the full-length virally encoded E2 transactivator and replication factor (E2TA) and in cis by the simian virus 40 enhancer. The constitutive enhancer induced the production of E2TA by activating all the major viral early promoters upstream of the E2 open reading frame. Complementation experiments using a temperature-sensitive E2TA mutant indicated that the constitutive enhancer was necessary for the maintenance of viral DNA replication within latently infected cells and implied that viral transcription under the regulation of the constitutive enhancer may be controlled during the cell cycle. The constitutive enhancer is a master regulatory control region for establishing and maintaining BPV-1 latency, and its characteristics reveal some analogies with cell type-specific enhancer elements recognized in the human papillomaviruses.

  16. Calcein represses human papillomavirus 16 E1-E2 mediated DNA replication via blocking their binding to the viral origin of replication.

    Science.gov (United States)

    Das, Dipon; Smith, Nathan W; Wang, Xu; Richardson, Stacie L; Hartman, Matthew C T; Morgan, Iain M

    2017-08-01

    Human papillomaviruses are causative agents in several human diseases ranging from genital warts to ano-genital and oropharyngeal cancers. Currently only symptoms of HPV induced disease are treated; there are no antivirals available that directly target the viral life cycle. Previously, we determined that the cellular protein TopBP1 interacts with the HPV16 replication/transcription factor E2. This E2-TopBP1 interaction is essential for optimal E1-E2 DNA replication and for the viral life cycle. The drug calcein disrupts the interaction of TopBP1 with itself and other host proteins to promote cell death. Here we demonstrate that calcein blocks HPV16 E1-E2 DNA replication via blocking the viral replication complex forming at the origin of replication. This occurs at non-toxic levels of calcein and demonstrates specificity as it does not block the ability of E2 to regulate transcription. We propose that calcein or derivatives could be developed as an anti-HPV therapeutic. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Reverse Genetics System Demonstrates that Rotavirus Nonstructural Protein NSP6 Is Not Essential for Viral Replication in Cell Culture.

    Science.gov (United States)

    Komoto, Satoshi; Kanai, Yuta; Fukuda, Saori; Kugita, Masanori; Kawagishi, Takahiro; Ito, Naoto; Sugiyama, Makoto; Matsuura, Yoshiharu; Kobayashi, Takeshi; Taniguchi, Koki

    2017-11-01

    The use of overlapping open reading frames (ORFs) to synthesize more than one unique protein from a single mRNA has been described for several viruses. Segment 11 of the rotavirus genome encodes two nonstructural proteins, NSP5 and NSP6. The NSP6 ORF is present in the vast majority of rotavirus strains, and therefore the NSP6 protein would be expected to have a function in viral replication. However, there is no direct evidence of its function or requirement in the viral replication cycle yet. Here, taking advantage of a recently established plasmid-only-based reverse genetics system that allows rescue of recombinant rotaviruses entirely from cloned cDNAs, we generated NSP6-deficient viruses to directly address its significance in the viral replication cycle. Viable recombinant NSP6-deficient viruses could be engineered. Single-step growth curves and plaque formation of the NSP6-deficient viruses confirmed that NSP6 expression is of limited significance for RVA replication in cell culture, although the NSP6 protein seemed to promote efficient virus growth. IMPORTANCE Rotavirus is one of the most important pathogens of severe diarrhea in young children worldwide. The rotavirus genome, consisting of 11 segments of double-stranded RNA, encodes six structural proteins (VP1 to VP4, VP6, and VP7) and six nonstructural proteins (NSP1 to NSP6). Although specific functions have been ascribed to each of the 12 viral proteins, the role of NSP6 in the viral replication cycle remains unknown. In this study, we demonstrated that the NSP6 protein is not essential for viral replication in cell culture by using a recently developed plasmid-only-based reverse genetics system. This reverse genetics approach will be successfully applied to answer questions of great interest regarding the roles of rotaviral proteins in replication and pathogenicity, which can hardly be addressed by conventional approaches. Copyright © 2017 American Society for Microbiology.

  18. HIV-1 nef suppression by virally encoded microRNA

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    Brisibe Ebiamadon

    2004-12-01

    Full Text Available Abstract Background MicroRNAs (miRNAs are 21~25-nucleotides (nt long and interact with mRNAs to trigger either translational repression or RNA cleavage through RNA interference (RNAi, depending on the degree of complementarity with the target mRNAs. Our recent study has shown that HIV-1 nef dsRNA from AIDS patients who are long-term non-progressors (LTNPs inhibited the transcription of HIV-1. Results Here, we show the possibility that nef-derived miRNAs are produced in HIV-1 persistently infected cells. Furthermore, nef short hairpin RNA (shRNA that corresponded to a predicted nef miRNA (~25 nt, miR-N367 can block HIV-1 Nef expression in vitro and the suppression by shRNA/miR-N367 would be related with low viremia in an LTNP (15-2-2. In the 15-2-2 model mice, the weight loss, which may be rendered by nef was also inhibited by shRNA/miR-N367 corresponding to suppression of nef expression in vivo. Conclusions These data suggest that nef/U3 miRNAs produced in HIV-1-infected cells may suppress both Nef function and HIV-1 virulence through the RNAi pathway.

  19. Factors Associated With the Control of Viral Replication and Virologic Breakthrough in a Recently Infected HIV-1 Controller

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    Victoria E. Walker-Sperling

    2017-02-01

    Full Text Available HIV-1 controllers are patients who control HIV-1 viral replication without antiretroviral therapy. Control is achieved very early in the course of infection, but the mechanisms through which viral replication is restricted are not fully understood. We describe a patient who presented with acute HIV-1 infection and was found to have an HIV-1 RNA level of <100 copies/mL. She did not have any known protective HLA alleles, but significant immune activation of CD8+ T cells and natural killer (NK cells was present, and both cell types inhibited viral replication. Virus cultured from this patient replicated as well in vitro as virus isolated from her partner, a patient with AIDS who was the source of transmission. Virologic breakthrough occurred 9 months after her initial presentation and was associated with an increase in CD4+ T cell activation levels and a significant decrease in NK cell inhibitory capacity. Remarkably, CD8+ T cell inhibitory capacity was preserved and there were no new escape mutations in targeted Gag epitopes. These findings suggest that fully replication-competent virus can be controlled in acute HIV-1 infection in some patients without protective HLA alleles and that NK cell responses may contribute to this early control of viral replication.

  20. An Ago2-associated capped transcriptional start site small RNA suppresses adenovirus DNA replication.

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    Kamel, Wael; Akusjärvi, Göran

    2017-11-01

    Here we show that the adenovirus major late promoter produces a 31-nucleotide transcriptional start site small RNA (MLP-TSS-sRNA) that retains the 7-methylguanosine (m7G)-cap and is incorporated onto Ago2-containing RNA-induced silencing complexes (RISC) in human adenovirus-37 infected cells. RNA polymerase II CLIP (UV-cross linking immunoprecipitation) experiments suggest that the MLP-TSS-sRNA is produced by promoter proximal stalling/termination of RNA polymerase II transcription at the site of the small RNA 3' end. The MLP-TSS-sRNA is highly stable in cells and functionally active, down-regulating complementary targets in a sequence and dose-dependent manner. The MLP-TSS-sRNA is transcribed from the opposite strand to the adenoviral DNA polymerase and preterminal protein mRNAs, two essential viral replication proteins. We show that the MLP-TSS-sRNA act in trans to reduce DNA polymerase and preterminal protein mRNA expression. As a consequence of this, the MLP-TSS-sRNA has an inhibitory effect on the efficiency of viral DNA replication. Collectively, our results suggest that this novel sRNA may serve a regulatory function controlling viral genome replication during a lytic and/or persistent adenovirus infection in its natural host. © 2017 Kamel and Akusjärvi; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  1. Autographa californica multiple nucleopolyhedrovirus DNA polymerase C terminus is required for nuclear localization and viral DNA replication.

    Science.gov (United States)

    Feng, Guozhong; Krell, Peter J

    2014-09-01

    The DNA polymerase (DNApol) of the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is essential for viral DNA replication. The DNApol exonuclease and polymerase domains are highly conserved and are considered functional in DNA replication. However, the role of the DNApol C terminus has not yet been characterized. To identify whether only the exonuclease and polymerase domains are sufficient for viral DNA replication, several DNApol C-terminal truncations were cloned into a dnapol-null AcMNPV bacmid with a green fluorescent protein (GFP) reporter. Surprisingly, most of the truncation constructs, despite containing both exonuclease and polymerase domains, could not rescue viral DNA replication and viral production in bacmid-transfected Sf21 cells. Moreover, GFP fusions of these same truncations failed to localize to the nucleus. Truncation of the C-terminal amino acids 950 to 984 showed nuclear localization but allowed for only limited and delayed viral spread. The C terminus contains a typical bipartite nuclear localization signal (NLS) motif at residues 804 to 827 and a monopartite NLS motif at residues 939 to 948. Each NLS, as a GFP fusion peptide, localized to the nucleus, but both NLSs were required for nuclear localization of DNApol. Alanine substitutions in a highly conserved baculovirus DNApol sequence at AcMNPV DNApol amino acids 972 to 981 demonstrated its importance for virus production and DNA replication. Collectively, the data indicated that the C terminus of AcMNPV DNApol contains two NLSs and a conserved motif, all of which are required for nuclear localization of DNApol, viral DNA synthesis, and virus production. The baculovirus DNA polymerase (DNApol) is a highly specific polymerase that allows viral DNA synthesis and hence virus replication in infected insect cells. We demonstrated that the exonuclease and polymerase domains of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) alone are insufficient for viral

  2. Viral DNA Replication Orientation and hnRNPs Regulate Transcription of the Human Papillomavirus 18 Late Promoter.

    Science.gov (United States)

    Wang, Xiaohong; Liu, Haibin; Ge, Hui; Ajiro, Masahiko; Sharma, Nishi R; Meyers, Craig; Morozov, Pavel; Tuschl, Thomas; Klar, Amar; Court, Donald; Zheng, Zhi-Ming

    2017-05-30

    The life cycle of human papillomaviruses (HPVs) is tightly linked to keratinocyte differentiation. Although expression of viral early genes is initiated immediately upon virus infection of undifferentiated basal cells, viral DNA amplification and late gene expression occur only in the mid to upper strata of the keratinocytes undergoing terminal differentiation. In this report, we show that the relative activity of HPV18 TATA-less late promoter P 811 depends on its orientation relative to that of the origin (Ori) of viral DNA replication and is sensitive to the eukaryotic DNA polymerase inhibitor aphidicolin. Additionally, transfected 70-nucleotide (nt)-long single-strand DNA oligonucleotides that are homologous to the region near Ori induce late promoter activity. We also found that promoter activation in raft cultures leads to production of the late promoter-associated, sense-strand transcription initiation RNAs (tiRNAs) and splice-site small RNAs (spliRNAs). Finally, a cis -acting AAGTATGCA core element that functions as a repressor to the promoter was identified. This element interacts with hnRNP D0B and hnRNP A/B factors. Point mutations in the core prevented binding of hnRNPs and increased the promoter activity. Confirming this result, knocking down the expression of both hnRNPs in keratinocytes led to increased promoter activity. Taking the data together, our study revealed the mechanism of how the HPV18 late promoter is regulated by DNA replication and host factors. IMPORTANCE It has been known for decades that the activity of viral late promoters is associated with viral DNA replication among almost all DNA viruses. However, the mechanism of how DNA replication activates the viral late promoter and what components of the replication machinery are involved remain largely unknown. In this study, we characterized the P 811 promoter region of HPV18 and demonstrated that its activation depends on the orientation of DNA replication. Using single

  3. Mutational analysis of varicella-zoster virus (VZV) immediate early protein (IE62) subdomains and their importance in viral replication

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    Khalil, Mohamed I., E-mail: mkhalil2@stanford.edu [Departments of Pediatrics and Microbiology & Immunology, Stan ford University School of Medicine, Stanford, CA (United States); Department of Molecular Biology, National Research Centre, El-Buhouth St., Cairo (Egypt); Che, Xibing; Sung, Phillip; Sommer, Marvin H. [Departments of Pediatrics and Microbiology & Immunology, Stan ford University School of Medicine, Stanford, CA (United States); Hay, John [Department of Microbiology and Immunology, School of Medicine and Biomedical Science, University at Buffalo, Buffalo, NY (United States); Arvin, Ann M. [Departments of Pediatrics and Microbiology & Immunology, Stan ford University School of Medicine, Stanford, CA (United States)

    2016-05-15

    VZV IE62 is an essential, immediate-early, tegument protein and consists of five domains. We generated recombinant viruses carrying mutations in the first three IE62 domains and tested their influence on VZV replication kinetics. The mutations in domain I did not affect replication kinetics while domain II mutations, disrupting the DNA binding and dimerization domain (DBD), were lethal for VZV replication. Mutations in domain III of the nuclear localization signal (NLS) and the two phosphorylation sites S686A/S722A resulted in slower growth in early and late infection respectively and were associated with IE62 accumulation in the cytoplasm and nucleus respectively. This study mapped the functional domains of IE62 in context of viral infection, indicating that DNA binding and dimerization domain is essential for VZV replication. In addition, the correct localization of IE62, whether nuclear or cytoplasmic, at different points in the viral life cycle, is important for normal progression of VZV replication. - Highlights: • Mutation of IE62 domain I did not affect VZV replication in melanoma cells. • IE62 domain II and III are important for VZV replication in melanoma cells. • Mutations of IE62 domain II (DBD) were lethal for virus replication. • Mutations of IE62 NLS and phosphorylation sites inhibited VZV replication. • NLS and S686A/S722A mutations altered localization of IE62 during early and late infection.

  4. The ubiquitin-conjugating system: multiple roles in viral replication and infection.

    Science.gov (United States)

    Calistri, Arianna; Munegato, Denis; Carli, Ilaria; Parolin, Cristina; Palù, Giorgio

    2014-05-06

    Through the combined action of ubiquitinating and deubiquitinating enzymes, conjugation of ubiquitin to a target protein acts as a reversible post-translational modification functionally similar to phosphorylation. Indeed, ubiquitination is more and more recognized as a central process for the fine regulation of many cellular pathways. Due to their nature as obligate intracellular parasites, viruses rely on the most conserved host cell machineries for their own replication. Thus, it is not surprising that members from almost every viral family are challenged by ubiquitin mediated mechanisms in different steps of their life cycle and have evolved in order to by-pass or exploit the cellular ubiquitin conjugating system to maximize their chance to establish a successful infection. In this review we will present several examples of the complex interplay that links viruses and the ubiquitin conjugation machinery, with a special focus on the mechanisms evolved by the human immunodeficiency virus to escape from cellular restriction factors and to exit from infected cells.

  5. Characterization of the adenoassociated virus Rep protein complex formed on the viral origin of DNA replication

    International Nuclear Information System (INIS)

    Li Zengi; Brister, J. Rodney; Im, Dong-Soo; Muzyczka, Nicholas

    2003-01-01

    Interaction between the adenoassociated virus (AAV) replication proteins, Rep68 and 78, and the viral terminal repeats (TRs) is mediated by a DNA sequence termed the Rep-binding element (RBE). This element is necessary for Rep-mediated unwinding of duplex DNA substrates, directs Rep catalyzed cleavage of the AAV origin of DNA replication, and is required for viral transcription and proviral integration. Six discrete Rep complexes with the AAV TR substrates have been observed in vitro, and cross-linking studies suggest these complexes contain one to six molecules of Rep. However, the functional relationship between Rep oligomerization and biochemical activity is unclear. Here we have characterized Rep complexes that form on the AAV TR. Both Rep68 and Rep78 appear to form the same six complexes with the AAV TR, and ATP seems to stimulate formation of specific, higher order complexes. When the sizes of these Rep complexes were estimated on native polyacrylamide gels, the four slower migrating complexes were larger than predicted by an amount equivalent to one or two TRs. To resolve this discrepancy, the molar ratio of protein and DNA was calculated for the three largest complexes. Data from these experiments indicated that the larger complexes included multiple TRs in addition to multiple Rep molecules and that the Rep-to-TR ratio was approximately 2. The two largest complexes were also associated with increased Rep-mediated, origin cleavage activity. Finally, we characterized a second, Rep-mediated cleavage event that occurs adjacent to the normal nicking site, but on the opposite strand. This second site nicking event effectively results in double-stranded DNA cleavage at the normal nicking site

  6. Hepatitis B Virus Stimulated Fibronectin Facilitates Viral Maintenance and Replication through Two Distinct Mechanisms.

    Directory of Open Access Journals (Sweden)

    Sheng Ren

    Full Text Available Fibronectin (FN is a high molecular weight extracellular matrix protein that functions in cell adhesion, growth, migration, and embryonic development. However, little is known about the role of FN during viral infection. In the present study, we found significantly higher levels of FN in sera, and liver tissues from hepatitis B virus (HBV patients relative to healthy individuals. HBV expression enhanced FN mRNA and protein levels in the hepatic cell lines Huh7 and HepG2. HBV infection of susceptible HepG2-sodium taurocholate co-transporting polypeptide cells also increased FN expression. We also found that transcriptional factor specificity protein 1 was involved in the induction of FN by HBV. Knockdown of FN expression significantly inhibited HBV DNA replication and protein synthesis through activating endogenous IFN-α production. In addition, FN interacted with the transforming growth factor β-activated protein kinase 1 (TAK1 and TAK1-binding protein complex and attenuated interferon signaling by inhibiting TAK1 phosphorylation. Furthermore, the nuclear translocation of NF-κB/p65 was found to be inhibited by FN. We also observed that FN promoted HBV enhancers to support HBV expression. These results suggest novel functions of endogenous FN involved in immune evasion and maintenance of HBV replication.

  7. In vivo evolution of the gp90 gene and consistently low plasma viral load during transient immune suppression demonstrate the safety of an attenuated equine infectious anemia virus (EIAV) vaccine.

    Science.gov (United States)

    Ma, Jian; Jiang, Chenggang; Lin, Yuezhi; Wang, Xuefeng; Zhao, Liping; Xiang, Wenhua; Shao, Yiming; Shen, Rongxian; Kong, Xiangang; Zhou, Jianhua

    2009-01-01

    To study the in vivo evolution of the attenuated Chinese equine infectious anemia virus (EIAV) vaccine, viral gp90 gene variation and virus replication in immunosuppressed hosts were investigated. The results showed that after vaccination, the gp90 gene followed an evolutionary trend of declining diversity. The trend coincided with the maturation of immunity to EIAV, and eventually, the gp90 gene became highly homologous. The sequences of these predominant quasispecies were consistently detected up to 18 months after vaccination. Furthermore, after transient immune suppression with dexamethasone, the plasma viral RNA copy number of the vaccine strain in three vaccinated ponies remained consistently below the "pathogenic threshold" level, while the viral load increased by 25,000-fold in the positive control of an inapparent carrier of the parental virulent strain. This study is the first to provide evidence for the safety of an attenuated lentiviral vaccine with decreased genomic diversity and consistently low viral replication under suppressed immunity.

  8. Jurisdiction level differences in HIV diagnosis, retention in care, and viral suppression in the United States.

    Science.gov (United States)

    Gray, Kristen Mahle; Cohen, Stacy M; Hu, Xiaohong; Li, Jianmin; Mermin, Jonathan; Hall, H Irene

    2014-02-01

    Using data from the National HIV Surveillance System, we determined the number of persons diagnosed with HIV and the percentages of persons linked to care, retained in care, and virally suppressed across 19 jurisdictions with complete reporting of CD4 and viral load test results. Reports from these jurisdictions represent 37% of persons diagnosed with HIV infection in the United States in 2011. Although 80% of persons diagnosed in 2011 were linked to HIV medical care within 3 months of diagnosis, half of all persons living with HIV in the 19 jurisdictions were not receiving ongoing care in 2010. In addition, 43% of persons living with HIV by year-end 2009 and alive at year-end 2010 did not have a suppressed viral load, with substantial variability across the 19 jurisdictions. These data highlight the need for improved outcomes along each step of the HIV continuum of care.

  9. Evaluation of chimeric yellow fever 17D/dengue viral replication in ticks.

    Science.gov (United States)

    Kazimírová, Mária; Mantel, Nathalie; Raynaud, Sandrine; Slovák, Mirko; Ustaniková, Katarína; Lang, Jean; Guy, Bruno; Barban, Veronique; Labuda, Milan

    2012-11-01

    Chimeric yellow fever 17D/DENV-1-4 viruses (CYD-1-4) have been developed as a tetravalent dengue vaccine candidate which is currently being evaluated in efficacy trials in Asia and America. While YF 17D and DENV are mosquito-borne flaviviruses, it has been shown that CYD-1-4 do not replicate after oral infection in mosquitoes and are not transmitted to new hosts. To further document the risk of environmental dissemination of these viruses, we evaluated the replication of CYD-1-4 in ticks, the vector of tick-borne encephalitis virus (TBEV), another member of the flavivirus family. Females of two hard tick species, Ixodes ricinus and Rhipicephalus appendiculatus, were inoculated intracoelomically with CYD-1-4 viruses and parent viruses (DENV-1-4 and YF 17D). Virus persistence and replication was assessed 2, 16, and 44 days post-inoculation by plaque titration and qRT-PCR. CYD-1-4 viruses were detected in I. ricinus ticks at early time points post-inoculation, but with infectious titers at least 100-fold lower than those observed in TBEV-infected ticks. Unlike TBEV, complete viral clearance occurred by day 44 in most ticks except for CYD-2, which had a tendency to decline. In addition, while about 70% of TBEV-infected I. ricinus nymphs acquired infection by co-feeding with infected tick females on non-viremic hosts, no co-feeding transmission of CYD-2 virus was detected. Based on these results, we conclude that the risk of dissemination of the candidate vaccine viruses by tick bite is highly unlikely.

  10. Effect on HIV-1 viral replication capacity of DTG-resistance mutations in NRTI/NNRTI resistant viruses.

    Science.gov (United States)

    Pham, Hanh T; Mesplède, Thibault; Wainberg, Mark A

    2016-04-30

    Recommended regimens for HIV-positive individuals include the co-administration of dolutegravir (DTG) with two reverse transcriptase inhibitors (RTIs). Although rare, emerging resistance against DTG is often associated with the R263K substitution in integrase. In-vitro-selected R263K was associated with impaired viral replication capacity, DNA integration, and integrase strand-transfer activity, especially when accompanied by the secondary mutation H51Y. Given the reduced fitness of RTI-resistant viruses, we investigated potential impacts on viral replication of combining R263K and H51Y/R263K with major RTI-resistance substitutions including K65R, L74V, K103N, E138K, and M184I/V. We combined the R263K or H51Y/R263K with RTI-resistance mutations into the proviral plasmid pNL4.3 and measured the resulting viral infectiousness, replication capacity, and ability to integrate viral DNA into host cells. Infectiousness was determined by luciferase assay in TZM-bl cells. Replicative capacity was monitored over 7 days and viral DNA integration was studied by real-time Alu-qPCR in PM1 cells. We found that viral infectiousness, replication capacities and integration levels were greatly reduced in triple mutants, i.e. H51Y/R263K plus a RT mutation, and moderately reduced in double mutants, i.e. R263K plus a RT mutation, compared to wild-type and single RT-mutant viruses. Our findings help to explain the absence of RTI mutations in individuals who experienced DTG-treatment failure.

  11. Activated MEK Suppresses Activation of PKR and Enables Efficient Replication and In Vivo Oncolysis by Δγ134.5 Mutants of Herpes Simplex Virus 1

    Science.gov (United States)

    Smith, Kerrington D.; Mezhir, James J.; Bickenbach, Kai; Veerapong, Jula; Charron, Jean; Posner, Mitchell C.; Roizman, Bernard; Weichselbaum, Ralph R.

    2006-01-01

    Herpes simplex virus mutants lacking the γ134.5 gene are not destructive to normal tissues but are potent cytolytic agents in human tumor cells in which the activation of double-stranded RNA-dependent protein kinase (PKR) is suppressed. Thus, replication of a Δγ134.5 mutant (R3616) in 12 genetically defined cancer cell lines correlates with suppression of PKR but not with the genotype of RAS. Extensive analyses of two cell lines transduced with either dominant negative MEK (dnMEK) or constitutively active MEK (caMEK) indicated that in R3616 mutant-infected cells dnMEK enabled PKR activation and decreased virus yields, whereas caMEK suppressed PKR and enabled better viral replication and cell destruction in transduced cells in vitro or in mouse xenografts. The results indicate that activated MEK mediates the suppression of PKR and that the status of MEK predicts the ability of Δγ134.5 mutant viruses to replicate in and destroy tumor cells. PMID:16414988

  12. CTLA-4+PD-1-Memory CD4+T Cells Critically Contribute to Viral Persistence in Antiretroviral Therapy-Suppressed, SIV-Infected Rhesus Macaques.

    Science.gov (United States)

    McGary, Colleen S; Deleage, Claire; Harper, Justin; Micci, Luca; Ribeiro, Susan P; Paganini, Sara; Kuri-Cervantes, Leticia; Benne, Clarisse; Ryan, Emily S; Balderas, Robert; Jean, Sherrie; Easley, Kirk; Marconi, Vincent; Silvestri, Guido; Estes, Jacob D; Sekaly, Rafick-Pierre; Paiardini, Mirko

    2017-10-17

    Antiretroviral therapy (ART) suppresses viral replication in HIV-infected individuals but does not eliminate the reservoir of latently infected cells. Recent work identified PD-1 + follicular helper T (Tfh) cells as an important cellular compartment for viral persistence. Here, using ART-treated, SIV-infected rhesus macaques, we show that CTLA-4 + PD-1 - memory CD4 + T cells, which share phenotypic markers with regulatory T cells, were enriched in SIV DNA in blood, lymph nodes (LN), spleen, and gut, and contained replication-competent and infectious virus. In contrast to PD-1 + Tfh cells, SIV-enriched CTLA-4 + PD-1 - CD4 + T cells were found outside the B cell follicle of the LN, predicted the size of the persistent viral reservoir during ART, and significantly increased their contribution to the SIV reservoir with prolonged ART-mediated viral suppression. We have shown that CTLA-4 + PD-1 - memory CD4 + T cells are a previously unrecognized component of the SIV and HIV reservoir that should be therapeutically targeted for a functional HIV-1 cure. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Gefitinib and pyrrolidine dithiocarbamate decrease viral replication and cytokine production in dengue virus infected human monocyte cultures.

    Science.gov (United States)

    Duran, Anyelo; Valero, Nereida; Mosquera, Jesús; Fuenmayor, Edgard; Alvarez-Mon, Melchor

    2017-12-15

    The epidermal growth factor receptor (EGFR) and nucleotide-binding and oligomerization-domain containing 2 (NOD2) are important in cancer and in microbial recognition, respectively. These molecules trigger intracellular signaling pathways inducing the expression of inflammatory genes by NF-kB translocation. Gefitinib (GBTC) and pyrrolidine dithiocarbamate (PDTC) are capable of inhibiting EGFR/NOD2 and NF-kB, respectively. In earlier stages of dengue virus (DENV) infection, monocytes are capable of sustaining viral replication and increasing cytokine production, suggesting that monocyte/macrophages play an important role in early DENV replication. GBTC and PDTC have not been used to modify the pathogenesis of DENV in infected cells. This study was aimed to determine the effect of GBTC and PDTC on viral replication and cytokine production in DENV serotype 2 (DENV2)-infected human monocyte cultures. GBTC and PDTC were used to inhibit EGFR/NOD2 and NF-kB, respectively. Cytokine production was measured by ELISA and viral replication by plaque forming unit assay. Increased DENV2 replication and anti-viral cytokine production (IFN-α/β, TNF-α, IL-12 and IL-18) in infected cultures were found. These parameters were decreased after EGFR/NOD2 or NF-kB inhibitions. The inhibitory effects of GBTC and PDTC on viral replication and cytokine production can be beneficial in the treatment of patients infected by dengue and suggest a possible role of EGFR/NOD2 receptors and NF-kB in dengue pathogenesis. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Tonsillar crypt epithelium is an important extra-central nervous system site for viral replication in EV71 encephalomyelitis.

    Science.gov (United States)

    He, Yaoxin; Ong, Kien Chai; Gao, Zifen; Zhao, Xishun; Anderson, Virginia M; McNutt, Michael A; Wong, Kum Thong; Lu, Min

    2014-03-01

    Enterovirus 71 (EV71; family Picornaviridae, species human Enterovirus A) usually causes hand, foot, and mouth disease, which may rarely be complicated by fatal encephalomyelitis. We investigated extra-central nervous system (extra-CNS) tissues capable of supporting EV71 infection and replication, and have correlated tissue infection with expression of putative viral entry receptors, scavenger receptor B2 (SCARB2), and P-selectin glycoprotein ligand-1 (PSGL-1). Formalin-fixed, paraffin-embedded CNS and extra-CNS tissues from seven autopsy cases were examined by IHC and in situ hybridization to evaluate viral antigens and RNA. Viral receptors were identified with IHC. In all seven cases, the CNS showed stereotypical distribution of inflammation and neuronal localization of viral antigens and RNA, confirming the clinical diagnosis of EV71 encephalomyelitis. In six cases in which tonsillar tissues were available, viral antigens and/or RNA were localized to squamous epithelium lining the tonsillar crypts. Tissues from the gastrointestinal tract, pancreas, mesenteric nodes, spleen, and skin were all negative for viral antigens/RNA. Our novel findings strongly suggest that tonsillar crypt squamous epithelium supports active viral replication and represents an important source of viral shedding that facilitates person-to-person transmission by both the fecal-oral or oral-oral routes. It may also be a portal for viral entry. A correlation between viral infection and SCARB2 expression appears to be more significant than for PSGL-1 expression. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  15. Orthoretroviral-like prototype foamy virus gag-pol expression is compatible with viral replication

    Directory of Open Access Journals (Sweden)

    Reh Juliane

    2011-08-01

    Full Text Available Abstract Background Foamy viruses (FVs unlike orthoretroviruses express Pol as a separate precursor protein and not as a Gag-Pol fusion protein. A unique packaging strategy, involving recognition of briding viral RNA by both Pol precursor and Gag as well as potential Gag-Pol protein interactions, ensures Pol particle encapsidation. Results Several Prototype FV (PFV Gag-Pol fusion protein constructs were generated to examine whether PFV replication is compatible with an orthoretroviral-like Pol expression. During their analysis, non-particle-associated secreted Pol precursor protein was discovered in extracellular wild type PFV particle preparations of different origin, copurifying in simple virion enrichment protocols. Different analysis methods suggest that extracellular wild type PFV particles contain predominantly mature p85PR-RT and p40IN Pol subunits. Characterization of various PFV Gag-Pol fusion constructs revealed that PFV Pol expression in an orthoretroviral manner is compatible with PFV replication as long as a proteolytic processing between Gag and Pol proteins is possible. PFV Gag-Pol translation by a HIV-1 like ribosomal frameshift signal resulted in production of replication-competent virions, although cell- and particle-associated Pol levels were reduced in comparison to wild type. In-frame fusion of PFV Gag and Pol ORFs led to increased cellular Pol levels, but particle incorporation was only marginally elevated. Unlike that reported for similar orthoretroviral constructs, a full-length in-frame PFV Gag-Pol fusion construct showed wildtype-like particle release and infectivity characteristics. In contrast, in-frame PFV Gag-Pol fusion with C-terminal Gag ORF truncations or non-removable Gag peptide addition to Pol displayed wildtype particle release, but reduced particle infectivity. PFV Gag-Pol precursor fusion proteins with inactivated protease were highly deficient in regular particle release, although coexpression of p71Gag

  16. AdEasy-based cloning system to generate tropism expanded replicating adenoviruses expressing transgenes late in the viral life cycle

    NARCIS (Netherlands)

    Lie-A-Ling, M.; Bakker, C. T.; Wesseling, J. G.; Bosma, P. J.

    2005-01-01

    Replicating adenoviral vectors (RAds) hold great promise for the treatment of cancer. Significant therapeutic effects of these vectors do not only rely on tumor targeting but also on efficient release of viral progeny from host cells. Cytotoxic genes expressed late in the adenoviral life cycle can

  17. A combinational CRISPR/Cas9 gene-editing approach can halt HIV replication and prevent viral escape

    NARCIS (Netherlands)

    Lebbink, Robert Jan; de Jong, Dorien C M; Wolters, Femke; Kruse, Elisabeth M; van Ham, Petra M; Wiertz, Emmanuel J H J; Nijhuis, Monique

    2017-01-01

    HIV presents one of the highest evolutionary rates ever detected and combination antiretroviral therapy is needed to overcome the plasticity of the virus population and control viral replication. Conventional treatments lack the ability to clear the latent reservoir, which remains the major obstacle

  18. Modulation of HIV-1 Gag NC/p1 cleavage efficiency affects protease inhibitor resistance and viral replicative capacity

    NARCIS (Netherlands)

    N.M. van Maarseveen (Noortje); D. Andersson (Dan); M. Lepšík (Martin); A. Fun (Axel); P.J. Schipper (Pauline); D. de Jong (Dorien); C.A.B. Boucher (Charles); M. Nijhuis (Monique)

    2012-01-01

    textabstractBackground: Mutations in the substrate of HIV-1 protease, especially changes in the NC/p1 cleavage site, can directly contribute to protease inhibitor (PI) resistance and also compensate for defects in viral replicative capacity (RC) due to a drug resistant protease. These NC/p1 changes

  19. Suppression of the toll-like receptor 7-dependent type I interferon production pathway by autophagy resulting from enterovirus 71 and coxsackievirus A16 infections facilitates their replication.

    Science.gov (United States)

    Song, Jie; Hu, Yajie; Li, Jiaqi; Zheng, Huiwen; Wang, Jingjing; Guo, Lei; Shi, Haijng; Liu, Longding

    2018-01-01

    Toll-like receptors (TLRs) act as molecular sentinels, detecting invading viral pathogens and triggering host innate immune responses, including autophagy. However, many viruses have evolved a series of strategies to manipulate autophagy for their own benefit. Enterovirus 71 (EV71) and coxsackievirus A16 (CA16), as the primary agents causing hand, foot and mouth disease (HFMD), can induce autophagy leading to their replication. Therefore, the objective of this study was to investigate whether enhanced viral replication caused by autophagy in EV71 and CA16 infections was associated with a TLR-related signaling pathway. Our results demonstrate that complete autophagy and incomplete autophagy were observed in human bronchial epithelial (16HBE) cells infected with EV71 and CA16. Moreover, suppression of autophagy by the pharmacological modulator 3-MA significantly and clearly decreased the survival rates and viral replication of EV71 and CA16 in 16HBE cells. Inhibition of autophagy also enhanced the expression of molecules related to the TLR7-dependent type I interferon (IFN-I) production pathway, such as TLR7, MyD88, IRF7 and IFN-α/β. Finally, immunofluorescence staining demonstrated that TLR7 endosome marker M6PR levels were clearly reduced in EV71- and CA16-infected cells, while they were markedly elevated in infected cells treated with 3-MA. These findings suggest that increased EV71 and CA16 replication meditated by autophagy in 16HBE cells might promote degradation of the endosome, leading to suppression of the TLR7-mediated IFN-I signaling pathway.

  20. Chloroquine and its derivatives exacerbate B19V-associated anemia by promoting viral replication.

    Directory of Open Access Journals (Sweden)

    Claudia Bönsch

    Full Text Available BACKGROUND: An unexpectedly high seroprevalence and pathogenic potential of human parvovirus B19 (B19V have been observed in certain malaria-endemic countries in parallel with local use of chloroquine (CQ as first-line treatment for malaria. The aims of this study were to assess the effect of CQ and other common antimalarial drugs on B19V infection in vitro and the possible epidemiological consequences for children from Papua New Guinea (PNG. METHODOLOGY/PRINCIPAL FINDINGS: Viral RNA, DNA and proteins were analyzed in different cell types following infection with B19V in the presence of a range of antimalarial drugs. Relationships between B19V infection status, prior 4-aminoquinoline use and anemia were assessed in 200 PNG children <10 years of age participating in a case-control study of severe infections. In CQ-treated cells, the synthesis of viral RNA, DNA and proteins was significantly higher and occurred earlier than in control cells. CQ facilitates B19V infection by minimizing intracellular degradation of incoming particles. Only amodiaquine amongst other antimalarial drugs had a similar effect. B19V IgM seropositivity was more frequent in 111 children with severe anemia (hemoglobin <50 g/L than in 89 healthy controls (15.3% vs 3.4%; P = 0.008. In children who were either B19V IgM or PCR positive, 4-aminoquinoline use was associated with a significantly lower admission hemoglobin concentration. CONCLUSIONS/SIGNIFICANCE: Our data strongly suggest that 4-aminoquinoline drugs and their metabolites exacerbate B19V-associated anemia by promoting B19V replication. Consideration should be given for choosing a non-4-aminoquinoline drug to partner artemisinin compounds in combination antimalarial therapy.

  1. Hepatitis B Virus-Encoded MicroRNA Controls Viral Replication.

    Science.gov (United States)

    Yang, Xi; Li, Hongfeng; Sun, Huahui; Fan, Hongxia; Hu, Yaqi; Liu, Min; Li, Xin; Tang, Hua

    2017-05-15

    MicroRNAs (miRNAs) are a class of small, single-stranded, noncoding, functional RNAs. Hepatitis B virus (HBV) is an enveloped DNA virus with virions and subviral forms of particles that lack a core. It was not known whether HBV encodes miRNAs. Here, we identified an HBV-encoded miRNA (called HBV-miR-3) by deep sequencing and Northern blotting. HBV-miR-3 is located at nucleotides (nt) 373 to 393 of the HBV genome and was generated from 3.5-kb, 2.4-kb, and 2.1-kb HBV in a classic miRNA biogenesis (Drosha-Dicer-dependent) manner. HBV-miR-3 was highly expressed in hepatoma cell lines with an integrated HBV genome and HBV + hepatoma tumors. In patients with HBV infection, HBV-miR-3 was released into the circulation by exosomes and HBV virions, and HBV-miR-3 expression had a positive correlation with HBV titers in the sera of patients in the acute phase of HBV infection. More interestingly, we found that HBV-miR-3 represses HBsAg, HBeAg, and replication of HBV. HBV-miR-3 targets the unique site of the HBV 3.5-kb transcript to specifically reduce HBc protein expression, levels of pregenomic RNA (pgRNA), and HBV replication intermediate (HBV-RI) generation but does not affect the HBV DNA polymerase level, thus suppressing HBV virion production (replication). This may explain the low levels of HBV virion generation with abundant subviral particles lacking core during HBV replication, which may contribute to the development of persistent infection in patients. Taken together, our findings shed light on novel mechanisms by which HBV-encoded miRNA controls the process of self-replication by regulating HBV transcript during infection. IMPORTANCE Hepatitis B is a liver infection caused by the hepatitis B virus (HBV) that can become a long-term, chronic infection and lead to cirrhosis or liver cancer. HBV is a small DNA virus that belongs to the hepadnavirus family, with virions and subviral forms of particles that lack a core. MicroRNA (miRNA), a small (∼22-nt) noncoding RNA

  2. Wolbachia Blocks Viral Genome Replication Early in Infection without a Transcriptional Response by the Endosymbiont or Host Small RNA Pathways.

    Directory of Open Access Journals (Sweden)

    Stephanie M Rainey

    2016-04-01

    Full Text Available The intracellular endosymbiotic bacterium Wolbachia can protect insects against viral infection, and is being introduced into mosquito populations in the wild to block the transmission of arboviruses that infect humans and are a major public health concern. To investigate the mechanisms underlying this antiviral protection, we have developed a new model system combining Wolbachia-infected Drosophila melanogaster cell culture with the model mosquito-borne Semliki Forest virus (SFV; Togaviridae, Alphavirus. Wolbachia provides strong antiviral protection rapidly after infection, suggesting that an early stage post-infection is being blocked. Wolbachia does appear to have major effects on events distinct from entry, assembly or exit as it inhibits the replication of an SFV replicon transfected into the cells. Furthermore, it causes a far greater reduction in the expression of proteins from the 3' open reading frame than the 5' non-structural protein open reading frame, indicating that it is blocking the replication of viral RNA. Further to this separation of the replicase proteins and viral RNA in transreplication assays shows that uncoupling of viral RNA and replicase proteins does not overcome Wolbachia's antiviral activity. This further suggests that replicative processes are disrupted, such as translation or replication, by Wolbachia infection. This may occur by Wolbachia mounting an active antiviral response, but the virus did not cause any transcriptional response by the bacterium, suggesting that this is not the case. Host microRNAs (miRNAs have been implicated in protection, but again we found that host cell miRNA expression was unaffected by the bacterium and neither do our findings suggest any involvement of the antiviral siRNA pathway. We conclude that Wolbachia may directly interfere with early events in virus replication such as translation of incoming viral RNA or RNA transcription, and this likely involves an intrinsic (as opposed to

  3. Peretinoin, an Acyclic Retinoid, Inhibits Hepatitis B Virus Replication by Suppressing Sphingosine Metabolic Pathway In Vitro

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    Kazuhisa Murai

    2018-01-01

    Full Text Available Hepatocellular carcinoma (HCC frequently develops from hepatitis C virus (HCV and hepatitis B virus (HBV infection. We previously reported that peretinoin, an acyclic retinoid, inhibits HCV replication. This study aimed to examine the influence of peretinoin on the HBV lifecycle. HBV-DNA and covalently closed circular DNA (cccDNA were evaluated by a qPCR method in HepG2.2.15 cells. Peretinoin significantly reduced the levels of intracellular HBV-DNA, nuclear cccDNA, and HBV transcript at a concentration that did not induce cytotoxicity. Conversely, other retinoids, such as 9-cis, 13-cis retinoic acid (RA, and all-trans-retinoic acid (ATRA, had no effect or rather increased HBV replication. Mechanistically, although peretinoin increased the expression of HBV-related transcription factors, as observed for other retinoids, peretinoin enhanced the binding of histone deacetylase 1 (HDAC1 to cccDNA in the nucleus and negatively regulated HBV transcription. Moreover, peretinoin significantly inhibited the expression of SPHK1, a potential inhibitor of HDAC activity, and might be involved in hepatic inflammation, fibrosis, and HCC. SPHK1 overexpression in cells cancelled the inhibition of HBV replication induced by peretinoin. This indicates that peretinoin activates HDAC1 and thereby suppresses HBV replication by inhibiting the sphingosine metabolic pathway. Therefore, peretinoin may be a novel therapeutic agent for HBV replication and chemoprevention against HCC.

  4. The interaction between endogenous 30S ribosomal subunit protein S11 and Cucumber mosaic virus LS2b protein affects viral replication, infection and gene silencing suppressor activity.

    Directory of Open Access Journals (Sweden)

    Ruilin Wang

    Full Text Available Cucumber mosaic virus (CMV is a model virus for plant-virus protein interaction and mechanism research because of its wide distribution, high-level of replication and simple genome structure. The 2b protein is a multifunctional protein encoded by CMV that suppresses RNA silencing-based antiviral defense and contributes to CMV virulence in host plants. In this report, 12 host proteins were identified as CMV LS2b binding partners using the yeast two-hybrid screen system from the Arabidopsis thaliana cDNA library. Among the host proteins, 30S ribosomal subunit protein S11 (RPS11 was selected for further studies. The interaction between LS2b and full-length RPS11 was confirmed using the yeast two-hybrid system. Bimolecular fluorescence complementation (BIFC assays observed by confocal laser microscopy and Glutathione S-transferase (GST pull-down assays were used to verify the interaction between endogenous NbRPS11 and viral CMVLS2b both in vivo and in vitro. TRV-based gene silencing vector was used to knockdown NbRPS11 transcription, and immunoblot analysis revealed a decline in infectious viral RNA replication and a decrease in CMV infection in RPS11 down-regulated Nicotiana benthamiana plants. Thus, the knockdown of RPS11 likely inhibited CMV replication and accumulation. The gene silencing suppressor activity of CMV2b protein was reduced by the RPS11 knockdown. This study demonstrated that the function of viral LS2b protein was remarkably affected by the interaction with host RPS11 protein.

  5. Mutations in HIV-1 Reverse Transcriptase Affect the Errors Made in a Single Cycle of Viral Replication

    Science.gov (United States)

    Abram, Michael E.; Ferris, Andrea L.; Das, Kalyan; Quinoñes, Octavio; Shao, Wei; Tuske, Steven; Alvord, W. Gregory; Arnold, Eddy

    2014-01-01

    ABSTRACT The genetic variation in HIV-1 in patients is due to the high rate of viral replication, the high viral load, and the errors made during viral replication. Some of the mutations in reverse transcriptase (RT) that alter the deoxynucleoside triphosphate (dNTP)-binding pocket, including those that confer resistance to nucleoside/nucleotide analogs, affect dNTP selection during replication. The effects of mutations in RT on the spectrum (nature, position, and frequency) of errors made in vivo are poorly understood. We previously determined the mutation rate and the frequency of different types of mutations and identified hot spots for mutations in a lacZα (the α complementing region of lacZ) reporter gene carried by an HIV-1 vector that replicates using wild-type RT. We show here that four mutations (Y115F, M184V, M184I, and Q151M) in the dNTP-binding pocket of RT that had relatively small effects on the overall HIV-1 mutation rate (less than 3-fold compared to the wild type) significantly increased mutations at some specific positions in the lacZα reporter gene. We also show that changes in a sequence that flanks the reporter gene can affect the mutations that arise in the reporter. These data show that changes either in HIV-1 RT or in the sequence of the nucleic acid template can affect the spectrum of mutations made during viral replication. This could, by implication, affect the generation of drug-resistant mutants and immunological-escape mutants in patients. IMPORTANCE RT is the viral enzyme that converts the RNA genome of HIV into DNA. Errors made during replication allow the virus to escape from the host's immune system and to develop resistance to the available anti-HIV drugs. We show that four different mutations in RT which are known to be associated with resistance to anti-RT drugs modestly increased the overall frequency of errors made during viral replication. However, the increased errors were not uniformly distributed; the additional errors

  6. The Ubiquitin-Conjugating System: Multiple Roles in Viral Replication and Infection

    Directory of Open Access Journals (Sweden)

    Arianna Calistri

    2014-05-01

    Full Text Available Through the combined action of ubiquitinating and deubiquitinating enzymes, conjugation of ubiquitin to a target protein acts as a reversible post-translational modification functionally similar to phosphorylation. Indeed, ubiquitination is more and more recognized as a central process for the fine regulation of many cellular pathways. Due to their nature as obligate intracellular parasites, viruses rely on the most conserved host cell machineries for their own replication. Thus, it is not surprising that members from almost every viral family are challenged by ubiquitin mediated mechanisms in different steps of their life cycle and have evolved in order to by-pass or exploit the cellular ubiquitin conjugating system to maximize their chance to establish a successful infection. In this review we will present several examples of the complex interplay that links viruses and the ubiquitin conjugation machinery, with a special focus on the mechanisms evolved by the human immunodeficiency virus to escape from cellular restriction factors and to exit from infected cells.

  7. CD4 cell count and the risk of AIDS or death in HIV-Infected adults on combination antiretroviral therapy with a suppressed viral load

    DEFF Research Database (Denmark)

    Obel, Niels

    2012-01-01

    Most adults infected with HIV achieve viral suppression within a year of starting combination antiretroviral therapy (cART). It is important to understand the risk of AIDS events or death for patients with a suppressed viral load.......Most adults infected with HIV achieve viral suppression within a year of starting combination antiretroviral therapy (cART). It is important to understand the risk of AIDS events or death for patients with a suppressed viral load....

  8. Brachial amyotrophic diplegia in the setting of complete HIV viral load suppression.

    Science.gov (United States)

    Cachia, David; Izzy, Saef; Ionete, Carolina; Salameh, Johnny

    2012-12-06

    Brachial amyotrophic diplegia (BAD) is a rare segmental form of motor neuron disease which presents with asymmetric lower motor neuron weakness largely confined to the upper extremities (UE). In the case being reported, a 62-year-old gentleman on antiretroviral treatment since 1993, presented with left-arm weakness in 2007 that quickly progressed to involve the right arm. Complete HIV-viral load suppression had been achieved since 2003. Examination revealed lower motor neuron weakness in both UEs, worse proximally than distally and normal strength in the lower extremities (LEs). Nerve conduction studies showed reduced amplitudes of bilateral median and ulnar nerves' motor responses. Needle electromyography of bilateral UE showed active and chronic denervation/reinnervation changes with normal findings in both LEs. MRI of the cervical spine showed cord atrophy. This is the first case report describing a patient who presented with BAD in the setting of complete HIV-viral load suppression for many years.

  9. Endogenous expression of a high-affinity pseudoknot RNA aptamer suppresses replication of HIV-1.

    Science.gov (United States)

    Chaloin, Laurent; Lehmann, Maik Jörg; Sczakiel, Georg; Restle, Tobias

    2002-09-15

    Aptamers, small oligonucleotides derived from an in vitro evolution process called SELEX, are promising therapeutic and diagnostic agents. Although very effective in vitro, only a few examples are available showing their potential in vivo. We have analyzed the effect of a well characterized pseudoknot RNA aptamer selected for tight binding to human immunodeficiency virus (HIV) type 1 reverse transcriptase on HIV replication. Transient intracellular expression of a chimeric RNA consisting of the human initiator tRNA(Met) (tRNA(Meti))/aptamer sequence in human 293T cells showed inhibition of HIV particle release by >75% when the cells were co-transfected with proviral HIV-1 DNA. Subsequent virus production of human T-lymphoid C8166 cells, infected with viral particles derived from co-transfected 293T cells, was again reduced by >75% as compared with the control. As the observed effects are additive, in this model for virus spread, the total reduction of HIV particle formation by transient intracellular expression of the pseudoknot RNA aptamer amounts to >95%. Low-dose HIV infection of human T cells stably expressing the aptamer did not show any virus replication over a period of 35 days. This is the first example of an RNA aptamer selected against a viral enzyme target to show powerful antiviral activity in HIV-1-permissive human T-lymphoid cell lines.

  10. Analysis of IAV Replication and Co-infection Dynamics by a Versatile RNA Viral Genome Labeling Method

    Directory of Open Access Journals (Sweden)

    Dan Dou

    2017-07-01

    Full Text Available Genome delivery to the proper cellular compartment for transcription and replication is a primary goal of viruses. However, methods for analyzing viral genome localization and differentiating genomes with high identity are lacking, making it difficult to investigate entry-related processes and co-examine heterogeneous RNA viral populations. Here, we present an RNA labeling approach for single-cell analysis of RNA viral replication and co-infection dynamics in situ, which uses the versatility of padlock probes. We applied this method to identify influenza A virus (IAV infections in cells and lung tissue with single-nucleotide specificity and to classify entry and replication stages by gene segment localization. Extending the classification strategy to co-infections of IAVs with single-nucleotide variations, we found that the dependence on intracellular trafficking places a time restriction on secondary co-infections necessary for genome reassortment. Altogether, these data demonstrate how RNA viral genome labeling can help dissect entry and co-infections.

  11. HIV viral suppression and geospatial patterns of HIV antiretroviral therapy treatment facility use in Rakai, Uganda.

    Science.gov (United States)

    Billioux, Veena G; Grabowski, Mary K; Ssekasanvu, Joseph; Reynolds, Steven J; Berman, Amanda; Bazaale, Jeremiah; Patel, Eshan U; Bugos, Eva; Ndyanabo, Anthony; Kisakye, Alice; Kagaayi, Joseph; Gray, Ronald H; Nakigozi, Gertrude; Ssekubugu, Robert; Nalugoda, Fred; Serwadda, David; Wawer, Maria J; Chang, Larry W

    2018-03-27

    To assess geospatial patterns of HIV antiretroviral therapy (ART) treatment facility use and whether they were impacted by viral load suppression. We extracted data on the location and type of care services utilized by HIV-positive persons accessing ART between February 2015 and September 2016 from the Rakai Community Cohort Study in Uganda. The distance from Rakai Community Cohort Study households to facilities offering ART was calculated using the open street map road network. Modified Poisson regression was used to identify predictors of distance traveled and, for those traveling beyond their nearest facility, the probability of accessing services from a tertiary care facility. In total, 1554 HIV-positive participants were identified, of whom 68% had initiated ART. The median distance from households to the nearest ART facility was 3.10 km (interquartile range, 1.65-5.05), but the median distance traveled was 5.26 km (interquartile range, 3.00-10.03, P < 0.001) and 57% of individuals travelled further than their nearest facility for ART. Those with higher education and wealth were more likely to travel further. In total, 93% of persons on ART were virally suppressed, and there was no difference in the distance traveled to an ART facility between those with suppressed and unsuppressed viral loads (5.26 vs. 5.27 km, P = 0.650). Distance traveled to HIV clinics was increased with higher socioeconomic status, suggesting that wealthier individuals exercise greater choice. However, distance traveled did not vary by those who were or were not virally suppressed.

  12. Vital Signs-HIV Care Saves Lives: Viral Suppression is Key

    Centers for Disease Control (CDC) Podcasts

    2014-11-25

    This podcast is based on the December 2014 CDC Vital Signs report. For people living with HIV, Viral suppression is critical. By getting tested and taking HIV medicines, individuals living with HIV can achieve very low levels of HIV in the body.  Created: 11/25/2014 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 11/25/2014.

  13. Higher retention and viral suppression with adolescent-focused HIV clinic in South Africa.

    Directory of Open Access Journals (Sweden)

    Brian C Zanoni

    Full Text Available To determine retention in care and virologic suppression among HIV-infected adolescents and young adults attending an adolescent-friendly clinic compared to those attending the standard pediatric clinic at the same site.Retrospective cohort analysis.Government supported, hospital-based antiretroviral clinic in KwaZulu-Natal, South Africa.Two hundred forty-one perinatally HIV-infected adolescents and young adults aged 13 to 24 years attending an adolescent-friendly clinic or the standard pediatric clinic from April 2007 to November 2015.Attendance in an adolescent-friendly clinic compared to a standard pediatric clinic.Retention in care defined as one clinic visit or pharmacy refill in the prior 6 months; HIV-1 viral suppression defined as < 400 copies/ml.Overall, among 241 adolescents and young adults, retention was 89% (214/241 and viral suppression was 81% (196/241. Retention was higher among those attending adolescent clinic (95% versus standard pediatric clinic (85%; OR 3.7; 95% confidence interval (CI 1.2-11.1; p = 0.018. Multivariable logistic regression adjusted for age at ART initiation, gender, pre-ART CD4 count, months on ART, and tuberculosis history indicated higher odds of retention in adolescents and young adults attending adolescent compared to standard clinic (AOR = 8.5; 95% CI 2.3-32.4; p = 0.002. Viral suppression was higher among adolescents and young adults attending adolescent (91% versus standard pediatric clinic (80%; OR 2.5; 95% CI 1.1-5.8; p = 0.028. A similar multivariable logistic regression model indicated higher odds of viral suppression in adolescents and young adults attending adolescent versus standard pediatric clinic (AOR = 3.8; 95% CI 1.5-9.7; p = 0.005.Adolescents and young adults attending an adolescent-friendly clinic had higher retention in care and viral suppression compared to adolescents attending the standard pediatric clinic. Further studies are needed to prospectively assess the impact of adolescent

  14. Enterovirus 71 induces autophagy by regulating has-miR-30a expression to promote viral replication.

    Science.gov (United States)

    Fu, Yuxuan; Xu, Wentao; Chen, Deyan; Feng, Chunhong; Zhang, Li; Wang, Xiaohui; Lv, Xiaowen; Zheng, Nan; Jin, Yu; Wu, Zhiwei

    2015-12-01

    Enterovirus 71 (EV71), the etiological agent of hand-foot-and-mouth disease, has increasingly become a public health challenge around the world. Previous studies reported that EV71 infection can induce autophagic machinery to enhance viral replication in vitro and in vivo, but did not address the underlying mechanisms. Increasing evidence suggests that autophagy, in a virus-specific manner, may function to degrade viruses or facilitate viral replication. In this study, we reported that EV71 infection of human epidermoid carcinoma (Hep2) and African green monkey kidney cells (Vero) induced autophagy, which is beneficial for viral replication. Our investigation of the mechanisms revealed that EV71 infection resulted in the reduction of cellular miR-30a, which led to the inhibition of Beclin-1, a key autophagy-promoting gene that plays important roles at the early phase of autophagosome formation. We provided further evidence that by modulating cellular miR-30a level through either overexpression or inhibition, one can inhibit or promote EV71 replication, respectively, through regulating autophagic activity. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Association Between Food Insecurity and HIV Viral Suppression: A Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Aibibula, Wusiman; Cox, Joseph; Hamelin, Anne-Marie; McLinden, Taylor; Klein, Marina B; Brassard, Paul

    2017-03-01

    Although an increasing number of HIV infected people are accessing antiretroviral treatment, many do not achieve complete HIV viral suppression and remain at risk for AIDS and capable of HIV transmission. Food insecurity has been identified as a potential risk factor for poor virologic response, but the association between these factors has been inconsistently documented in the literature. We systematically searched five electronic databases and bibliographies of relevant studies through April 2015 and retrieved 11 studies that met our inclusion criteria, of which nine studies were conducted in North America and the remaining two studies were in Brazil and Uganda respectively. Meta-analyzed results indicated that experiencing food insecurity resulted in 29% lower odds of achieving complete HIV viral suppression (OR = 0.71, 95% CI 0.61-0.82) and this significant inverse association was consistently found regardless of study design, exposure measurement, and confounder adjustment methods. These findings suggest that food insecurity is a potential risk factor for incomplete HIV viral suppression in people living with HIV.

  16. Endoplasmic Reticulum Stress Induced Synthesis of a Novel Viral Factor Mediates Efficient Replication of Genotype-1 Hepatitis E Virus.

    Directory of Open Access Journals (Sweden)

    Vidya P Nair

    2016-04-01

    Full Text Available Hepatitis E virus (HEV causes acute hepatitis in many parts of the world including Asia, Africa and Latin America. Though self-limiting in normal individuals, it results in ~30% mortality in infected pregnant women. It has also been reported to cause acute and chronic hepatitis in organ transplant patients. Of the seven viral genotypes, genotype-1 virus infects humans and is a major public health concern in South Asian countries. Sporadic cases of genotype-3 and 4 infection in human and animals such as pigs, deer, mongeese have been reported primarily from industrialized countries. Genotype-5, 6 and 7 viruses are known to infect animals such as wild boar and camel, respectively. Genotype-3 and 4 viruses have been successfully propagated in the laboratory in mammalian cell culture. However, genotype-1 virus replicates poorly in mammalian cell culture and no other efficient model exists to study its life cycle. Here, we report that endoplasmic reticulum (ER stress promotes genotype-1 HEV replication by inducing cap-independent, internal initiation mediated translation of a novel viral protein (named ORF4. Importantly, ORF4 expression and stimulatory effect of ER stress inducers on viral replication is specific to genotype-1. ORF4 protein sequence is mostly conserved among genotype-1 HEV isolates and ORF4 specific antibodies were detected in genotype-1 HEV patient serum. ORF4 interacted with multiple viral and host proteins and assembled a protein complex consisting of viral helicase, RNA dependent RNA polymerase (RdRp, X, host eEF1α1 (eukaryotic elongation factor 1 isoform-1 and tubulinβ. In association with eEF1α1, ORF4 stimulated viral RdRp activity. Furthermore, human hepatoma cells that stably express ORF4 or engineered proteasome resistant ORF4 mutant genome permitted enhanced viral replication. These findings reveal a positive role of ER stress in promoting genotype-1 HEV replication and pave the way towards development of an efficient

  17. Recruitment of DNA replication and damage response proteins to viral replication centers during infection with NS2 mutants of Minute Virus of Mice (MVM).

    Science.gov (United States)

    Ruiz, Zandra; Mihaylov, Ivailo S; Cotmore, Susan F; Tattersall, Peter

    2011-02-20

    MVM NS2 is essential for viral DNA amplification, but its mechanism of action is unknown. A classification scheme for autonomous parvovirus-associated replication (APAR) center development, based on NS1 distribution, was used to characterize abnormal APAR body maturation in NS2null mutant infections, and their organization examined for defects in host protein recruitment. Since acquisition of known replication factors appeared normal, we looked for differences in invoked DNA damage responses. We observed widespread association of H2AX/MDC1 damage response foci with viral replication centers, and sequestration and complex hyperphosphorylation of RPA(32), which occurred in wildtype and mutant infections. Quantifying these responses by western transfer indicated that both wildtype and NS2 mutant MVM elicited ATM activation, while phosphorylation of ATR, already basally activated in asynchronous A9 cells, was downregulated. We conclude that MVM infection invokes multiple damage responses that influence the APAR environment, but that NS2 does not modify the recruitment of cellular proteins. Copyright © 2010 Elsevier Inc. All rights reserved.

  18. Association of Implementation of a Universal Testing and Treatment Intervention With HIV Diagnosis, Receipt of Antiretroviral Therapy, and Viral Suppression in East Africa.

    Science.gov (United States)

    Petersen, Maya; Balzer, Laura; Kwarsiima, Dalsone; Sang, Norton; Chamie, Gabriel; Ayieko, James; Kabami, Jane; Owaraganise, Asiphas; Liegler, Teri; Mwangwa, Florence; Kadede, Kevin; Jain, Vivek; Plenty, Albert; Brown, Lillian; Lavoy, Geoff; Schwab, Joshua; Black, Douglas; van der Laan, Mark; Bukusi, Elizabeth A; Cohen, Craig R; Clark, Tamara D; Charlebois, Edwin; Kamya, Moses; Havlir, Diane

    2017-06-06

    Antiretroviral treatment (ART) is now recommended for all HIV-positive persons. UNAIDS has set global targets to diagnose 90% of HIV-positive individuals, treat 90% of diagnosed individuals with ART, and suppress viral replication among 90% of treated individuals, for a population-level target of 73% of all HIV-positive persons with HIV viral suppression. To describe changes in the proportions of HIV-positive individuals with HIV viral suppression, HIV-positive individuals who had received a diagnosis, diagnosed individuals treated with ART, and treated individuals with HIV viral suppression, following implementation of a community-based testing and treatment program in rural East Africa. Observational analysis based on interim data from 16 rural Kenyan (n = 6) and Ugandan (n = 10) intervention communities in the SEARCH Study, an ongoing cluster randomized trial. Community residents who were 15 years or older (N = 77 774) were followed up for 2 years (2013-2014 to 2015-2016). HIV serostatus and plasma HIV RNA level were measured annually at multidisease health campaigns followed by home-based testing for nonattendees. All HIV-positive individuals were offered ART using a streamlined delivery model designed to reduce structural barriers, improve patient-clinician relationships, and enhance patient knowledge and attitudes about HIV. Primary outcome was viral suppression (plasma HIV RNAHIV-positive individuals, assessed at baseline and after 1 and 2 years. Secondary outcomes included HIV diagnosis, ART among previously diagnosed individuals, and viral suppression among those who had initiated ART. Among 77 774 residents (male, 45.3%; age 15-24 years, 35.1%), baseline HIV prevalence was 10.3% (7108 of 69 283 residents). The proportion of HIV-positive individuals with HIV viral suppression at baseline was 44.7% (95% CI, 43.5%-45.9%; 3464 of 7745 residents) and after 2 years of intervention was 80.2% (95% CI, 79.1%-81.2%; 5666 of 7068 residents), an

  19. A comparison of oncogene-induced senescence and replicative senescence: implications for tumor suppression and aging.

    Science.gov (United States)

    Nelson, David M; McBryan, Tony; Jeyapalan, Jessie C; Sedivy, John M; Adams, Peter D

    2014-06-01

    Cellular senescence is a stable proliferation arrest associated with an altered secretory pathway, the senescence-associated secretory phenotype. However, cellular senescence is initiated by diverse molecular triggers, such as activated oncogenes and shortened telomeres, and is associated with varied and complex physiological endpoints, such as tumor suppression and tissue aging. The extent to which distinct triggers activate divergent modes of senescence that might be associated with different physiological endpoints is largely unknown. To begin to address this, we performed gene expression profiling to compare the senescence programs associated with two different modes of senescence, oncogene-induced senescence (OIS) and replicative senescence (RS [in part caused by shortened telomeres]). While both OIS and RS are associated with many common changes in gene expression compared to control proliferating cells, they also exhibit substantial differences. These results are discussed in light of potential physiological consequences, tumor suppression and aging.

  20. Antiviral activity of double-stranded RNA-binding protein PACT against influenza A virus mediated via suppression of viral RNA polymerase.

    Science.gov (United States)

    Chan, Chi-Ping; Yuen, Chun-Kit; Cheung, Pak-Hin Hinson; Fung, Sin-Yee; Lui, Pak-Yin; Chen, Honglin; Kok, Kin-Hang; Jin, Dong-Yan

    2018-03-07

    PACT is a double-stranded RNA-binding protein that has been implicated in host-influenza A virus (IAV) interaction. PACT facilitates the action of RIG-I in the activation of the type I IFN response, which is suppressed by the viral nonstructural protein NS1. PACT is also known to interact with the IAV RNA polymerase subunit PA. Exactly how PACT exerts its antiviral activity during IAV infection remains to be elucidated. In the current study, we demonstrated the interplay between PACT and IAV polymerase. Induction of IFN-β by the IAV RNP complex was most robust when both RIG-I and PACT were expressed. PACT-dependent activation of IFN-β production was suppressed by the IAV polymerase subunits, polymerase acidic protein, polymerase basic protein 1 (PB1), and PB2. PACT associated with PA, PB1, and PB2. Compromising PACT in IAV-infected A549 cells resulted in the augmentation of viral RNA (vRNA) transcription and replication and IFN-β production. Furthermore, vRNA replication was boosted by knockdown of PACT in both A549 cells and IFN-deficient Vero cells. Thus, the antiviral activity of PACT is mediated primarily via its interaction with and inhibition of IAV polymerase. Taken together, our findings reveal a new facet of the host-IAV interaction in which the interplay between PACT and IAV polymerase affects the outcome of viral infection and antiviral response.-Chan, C.-P., Yuen, C.-K., Cheung, P.-H. H., Fung, S.-Y., Lui, P.-Y., Chen, H., Kok, K.-H., Jin, D.-Y. Antiviral activity of double-stranded RNA-binding protein PACT against influenza A virus mediated via suppression of viral RNA polymerase.

  1. Neonicotinoid clothianidin adversely affects insect immunity and promotes replication of a viral pathogen in honey bees

    Science.gov (United States)

    Di Prisco, Gennaro; Cavaliere, Valeria; Annoscia, Desiderato; Varricchio, Paola; Caprio, Emilio; Nazzi, Francesco; Gargiulo, Giuseppe; Pennacchio, Francesco

    2013-01-01

    Large-scale losses of honey bee colonies represent a poorly understood problem of global importance. Both biotic and abiotic factors are involved in this phenomenon that is often associated with high loads of parasites and pathogens. A stronger impact of pathogens in honey bees exposed to neonicotinoid insecticides has been reported, but the causal link between insecticide exposure and the possible immune alteration of honey bees remains elusive. Here, we demonstrate that the neonicotinoid insecticide clothianidin negatively modulates NF-κB immune signaling in insects and adversely affects honey bee antiviral defenses controlled by this transcription factor. We have identified in insects a negative modulator of NF-κB activation, which is a leucine-rich repeat protein. Exposure to clothianidin, by enhancing the transcription of the gene encoding this inhibitor, reduces immune defenses and promotes the replication of the deformed wing virus in honey bees bearing covert infections. This honey bee immunosuppression is similarly induced by a different neonicotinoid, imidacloprid, but not by the organophosphate chlorpyriphos, which does not affect NF-κB signaling. The occurrence at sublethal doses of this insecticide-induced viral proliferation suggests that the studied neonicotinoids might have a negative effect at the field level. Our experiments uncover a further level of regulation of the immune response in insects and set the stage for studies on neural modulation of immunity in animals. Furthermore, this study has implications for the conservation of bees, as it will contribute to the definition of more appropriate guidelines for testing chronic or sublethal effects of pesticides used in agriculture. PMID:24145453

  2. Neonicotinoid clothianidin adversely affects insect immunity and promotes replication of a viral pathogen in honey bees.

    Science.gov (United States)

    Di Prisco, Gennaro; Cavaliere, Valeria; Annoscia, Desiderato; Varricchio, Paola; Caprio, Emilio; Nazzi, Francesco; Gargiulo, Giuseppe; Pennacchio, Francesco

    2013-11-12

    Large-scale losses of honey bee colonies represent a poorly understood problem of global importance. Both biotic and abiotic factors are involved in this phenomenon that is often associated with high loads of parasites and pathogens. A stronger impact of pathogens in honey bees exposed to neonicotinoid insecticides has been reported, but the causal link between insecticide exposure and the possible immune alteration of honey bees remains elusive. Here, we demonstrate that the neonicotinoid insecticide clothianidin negatively modulates NF-κB immune signaling in insects and adversely affects honey bee antiviral defenses controlled by this transcription factor. We have identified in insects a negative modulator of NF-κB activation, which is a leucine-rich repeat protein. Exposure to clothianidin, by enhancing the transcription of the gene encoding this inhibitor, reduces immune defenses and promotes the replication of the deformed wing virus in honey bees bearing covert infections. This honey bee immunosuppression is similarly induced by a different neonicotinoid, imidacloprid, but not by the organophosphate chlorpyriphos, which does not affect NF-κB signaling. The occurrence at sublethal doses of this insecticide-induced viral proliferation suggests that the studied neonicotinoids might have a negative effect at the field level. Our experiments uncover a further level of regulation of the immune response in insects and set the stage for studies on neural modulation of immunity in animals. Furthermore, this study has implications for the conservation of bees, as it will contribute to the definition of more appropriate guidelines for testing chronic or sublethal effects of pesticides used in agriculture.

  3. Stearoyl coenzyme A desaturase 1 is associated with hepatitis C virus replication complex and regulates viral replication

    DEFF Research Database (Denmark)

    Nguyen, LN; Lim, YS; Pham, Long

    2014-01-01

    The hepatitis C virus (HCV) life cycle is tightly regulated by lipid metabolism of host cells. In order to identify host factors involved in HCV propagation, we have recently screened a small interfering RNA (siRNA) library targeting host genes that control lipid metabolism and lipid droplet...... formation using cell culture-grown HCV (HCVcc)-infected cells. We selected and characterized the gene encoding stearoyl coenzyme A (CoA) desaturase 1 (SCD1). siRNA-mediated knockdown or pharmacological inhibition of SCD1 abrogated HCV replication in both subgenomic replicon and Jc1-infected cells, while...... exogenous supplementation of either oleate or palmitoleate, products of SCD1 activity, resurrected HCV replication in SCD1 knockdown cells. SCD1 was coimmunoprecipitated with HCV nonstructural proteins and colocalized with both double-stranded RNA (dsRNA) and HCV nonstructural proteins, indicating that SCD1...

  4. Viral replication and lung lesions in BALB/c mice experimentally inoculated with avian metapneumovirus subgroup C isolated from chickens.

    Directory of Open Access Journals (Sweden)

    Li Wei

    Full Text Available Avian metapneumovirus (aMPV emerged as an important respiratory pathogen causing acute respiratory tract infection in avian species. Here we used a chicken aMPV subgroup C (aMPV/C isolate to inoculate experimentally BALB/c mice and found that the aMPV/C can efficiently replicate and persist in the lungs of mice for at least 21 days with a peak viral load at day 6 postinoculation. Lung pathological changes were characterized by increased inflammatory cells. Immunochemical assay showed the presence of viral antigens in the lungs and significant upregulation of pulmonary inflammatory cytokines and chemokines including MCP-1, MIP-1α, RANTES, IL-1β, IFN-γ, and TNF-α were detected following inoculation. These results indicate for the first time that chicken aMPV/C may replicate in the lung of mice. Whether aMPV/C has potential as zoonotic pathogen, further investigation will be required.

  5. Viral replication and lung lesions in BALB/c mice experimentally inoculated with avian metapneumovirus subgroup C isolated from chickens.

    Science.gov (United States)

    Wei, Li; Zhu, Shanshan; She, Ruiping; Hu, Fengjiao; Wang, Jing; Yan, Xu; Zhang, Chunyan; Liu, Shuhang; Quan, Rong; Li, Zixuan; Du, Fang; Wei, Ting; Liu, Jue

    2014-01-01

    Avian metapneumovirus (aMPV) emerged as an important respiratory pathogen causing acute respiratory tract infection in avian species. Here we used a chicken aMPV subgroup C (aMPV/C) isolate to inoculate experimentally BALB/c mice and found that the aMPV/C can efficiently replicate and persist in the lungs of mice for at least 21 days with a peak viral load at day 6 postinoculation. Lung pathological changes were characterized by increased inflammatory cells. Immunochemical assay showed the presence of viral antigens in the lungs and significant upregulation of pulmonary inflammatory cytokines and chemokines including MCP-1, MIP-1α, RANTES, IL-1β, IFN-γ, and TNF-α were detected following inoculation. These results indicate for the first time that chicken aMPV/C may replicate in the lung of mice. Whether aMPV/C has potential as zoonotic pathogen, further investigation will be required.

  6. Gender differences in mortality and CD4 count response among virally suppressed HIV-positive patients.

    Science.gov (United States)

    Maskew, Mhairi; Brennan, Alana T; Westreich, Daniel; McNamara, Lynne; MacPhail, A Patrick; Fox, Matthew P

    2013-02-01

    Treatment outcomes for antiretroviral therapy (ART) patients may vary by gender, but estimates from current evidence may be confounded by disease stage and adherence. We investigated the gender differences in treatment response among HIV-positive patients virally suppressed within 6 months of treatment initiation. We analyzed data from 7,354 patients initiating ART between April 2004 and April 2010 at Themba Lethu Clinic, a large urban public sector treatment facility in South Africa. We estimated the relations among gender, mortality, and mean CD4 response in HIV-infected adults virally suppressed within 6 months of treatment initiation and used inverse probability of treatment weights to correct estimates for loss to follow-up. Male patients had a 20% greater risk of death at both 24 months and 36 months of follow-up compared to females. Older patients and those with a low hemoglobin level or low body mass index (BMI) were at increased risk of mortality throughout follow-up. Men gained fewer CD4 cells after treatment initiation than did women. The mean differences in CD4 count gains made by women and men between baseline and 12, 24, and 36 months were 28.2 cells/mm(3) (95% confidence interval [CI] 22.2-34.3), 60.8 cells/mm(3) (95% CI 71.1-50.5 cells/mm(3)), and 83.0 cells/mm(3) (95% CI 97.1-68.8 cells/mm(3)), respectively. Additionally, patients with a current detectable viral load (>400 copies/mL) and older patients had a lower mean CD4 increase at the same time points. In this initially virally suppressed population, women showed consistently better immune response to treatment than did men. Promoting earlier uptake of HIV treatment among men may improve their immunologic outcomes.

  7. A discontinuous RNA platform mediates RNA virus replication: building an integrated model for RNA-based regulation of viral processes.

    Directory of Open Access Journals (Sweden)

    Baodong Wu

    2009-03-01

    Full Text Available Plus-strand RNA viruses contain RNA elements within their genomes that mediate a variety of fundamental viral processes. The traditional view of these elements is that of local RNA structures. This perspective, however, is changing due to increasing discoveries of functional viral RNA elements that are formed by long-range RNA-RNA interactions, often spanning thousands of nucleotides. The plus-strand RNA genomes of tombusviruses exemplify this concept by possessing different long-range RNA-RNA interactions that regulate both viral translation and transcription. Here we report that a third fundamental tombusvirus process, viral genome replication, requires a long-range RNA-based interaction spanning approximately 3000 nts. In vivo and in vitro analyses suggest that the discontinuous RNA platform formed by the interaction facilitates efficient assembly of the viral RNA replicase. This finding has allowed us to build an integrated model for the role of global RNA structure in regulating the reproduction of a eukaryotic RNA virus, and the insights gained have extended our understanding of the multifunctional nature of viral RNA genomes.

  8. Human polyoma JC virus minor capsid proteins, VP2 and VP3, enhance large T antigen binding to the origin of viral DNA replication: evidence for their involvement in regulation of the viral DNA replication.

    Science.gov (United States)

    Saribas, A Sami; Mun, Sarah; Johnson, Jaslyn; El-Hajmoussa, Mohammad; White, Martyn K; Safak, Mahmut

    2014-01-20

    JC virus (JCV) lytically infects the oligodendrocytes in the central nervous system in a subset of immunocompromized patients and causes the demyelinating disease, progressive multifocal leukoencephalopathy. JCV replicates and assembles into infectious virions in the nucleus. However, understanding the molecular mechanisms of its virion biogenesis remains elusive. In this report, we have attempted to shed more light on this process by investigating molecular interactions between large T antigen (LT-Ag), Hsp70 and minor capsid proteins, VP2/VP3. We demonstrated that Hsp70 interacts with VP2/VP3 and LT-Ag; and accumulates heavily in the nucleus of the infected cells. We also showed that VP2/VP3 associates with LT-Ag through their DNA binding domains resulting in enhancement in LT-Ag DNA binding to Ori and induction in viral DNA replication. Altogether, our results suggest that VP2/VP3 and Hsp70 actively participate in JCV DNA replication and may play critical roles in coupling of viral DNA replication to virion encapsidation. © 2013 Published by Elsevier Inc.

  9. Newcastle disease virus induces stable formation ofbona fidestress granules to facilitate viral replication through manipulating host protein translation.

    Science.gov (United States)

    Sun, Yingjie; Dong, Luna; Yu, Shengqing; Wang, Xiaoxu; Zheng, Hang; Zhang, Pin; Meng, Chunchun; Zhan, Yuan; Tan, Lei; Song, Cuiping; Qiu, Xusheng; Wang, Guijun; Liao, Ying; Ding, Chan

    2017-04-01

    Mammalian cells respond to various environmental stressors to form stress granules (SGs) by arresting cytoplasmic mRNA, protein translation element, and RNA binding proteins. Virus-induced SGs function in different ways, depending on the species of virus; however, the mechanism of SG regulation of virus replication is not well understood. In this study, Newcastle disease virus (NDV) triggered stable formation of bona fide SGs on HeLa cells through activating the protein kinase R (PKR)/eIF2α pathway. NDV-induced SGs contained classic SG markers T-cell internal antigen (TIA)-1, Ras GTPase-activating protein-binding protein (G3BP)-1, eukaryotic initiation factors, and small ribosomal subunit, which could be disassembled in the presence of cycloheximide. Treatment with nocodazole, a microtubule disruption drug, led to the formation of relatively small and circular granules, indicating that NDV infection induces canonical SGs. Furthermore, the role of SGs on NDV replication was investigated by knockdown of TIA-1 and TIA-1-related (TIAR) protein, the 2 critical components involved in SG formation from the HeLa cells, followed by NDV infection. Results showed that depletion of TIA-1 or TIAR inhibited viral protein synthesis, reduced extracellular virus yields, but increased global protein translation. FISH revealed that NDV-induced SGs contained predominantly cellular mRNA rather than viral mRNA. Deletion of TIA-1 or TIAR reduced NP mRNA levels in polysomes. These results demonstrate that NDV triggers stable formation of bona fide SGs, which benefit viral protein translation and virus replication by arresting cellular mRNA.-Sun, Y., Dong, L., Yu, S., Wang, X., Zheng, H., Zhang, P., Meng, C., Zhan, Y., Tan, L., Song, C., Qiu, X., Wang, G., Liao, Y., Ding, C. Newcastle disease virus induces stable formation of bona fide stress granules to facilitate viral replication through manipulating host protein translation. © FASEB.

  10. Altered Viral Replication and Cell Responses by Inserting MicroRNA Recognition Element into PB1 in Pandemic Influenza A Virus (H1N1) 2009

    Science.gov (United States)

    Shen, Xiaoyue; Sun, Wenkui; Shi, Yi; Xing, Zheng; Su, Xin

    2015-01-01

    Objective. MicroRNAs (miRNAs) are endogenous noncoding RNAs that spatiotemporally modulate mRNAs in a posttranscriptional manner. Engineering mutant viruses by inserting cell-specific miRNA recognition element (MRE) into viral genome may alter viral infectivity and host responses in vital tissues and organs infected with pandemic influenza A virus (H1N1) 2009 (H1N1pdm). Methods. In this study, we employed reverse genetics approach to generate a recombinant H1N1pdm with a cell-specific miRNA target sequence inserted into its PB1 genomic segment to investigate whether miRNAs are able to suppress H1N1pdm replication. We inserted an MRE of microRNA-let-7b (miR-let-7b) into the open reading frame of PB1 to test the feasibility of creating a cell-restricted H1N1pdm virus since let-7b is abundant in human bronchial epithelial cells. Results. miR-let-7b is rich in human bronchial epithelial cells (HBE). Incorporation of the miR-let-7b-MRE confers upon the recombinant H1N1pdm virus susceptibility to miR-let-7b targeting, suggesting that the H1N1pdm and influenza A viruses can be engineered to exert the desired replication restrictive effect and decrease infectivity in vital tissues and organs. Conclusions. This approach provides an additional layer of biosafety and thus has great potential for the application in the rational development of safer and more effective influenza viral vaccines. PMID:25788763

  11. Development of viable TAP-tagged dengue virus for investigation of host-virus interactions in viral replication.

    Science.gov (United States)

    Poyomtip, Teera; Hodge, Kenneth; Matangkasombut, Ponpan; Sakuntabhai, Anavaj; Pisitkun, Trairak; Jirawatnotai, Siwanon; Chimnaronk, Sarin

    2016-03-01

    Dengue virus (DENV) is a mosquito-borne flavivirus responsible for life-threatening dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS). The viral replication machinery containing the core non-structural protein 5 (NS5) is implicated in severe dengue symptoms but molecular details remain obscure. To date, studies seeking to catalogue and characterize interaction networks between viral NS5 and host proteins have been limited to the yeast two-hybrid system, computational prediction and co-immunoprecipitation (IP) of ectopically expressed NS5. However, these traditional approaches do not reproduce a natural course of infection in which a number of DENV NS proteins colocalize and tightly associate during the replication process. Here, we demonstrate the development of a recombinant DENV that harbours a TAP tag in NS5 to study host-virus interactions in vivo. We show that our engineered DENV was infective in several human cell lines and that the tags were stable over multiple viral passages, suggesting negligible structural and functional disturbance of NS5. We further provide proof-of-concept for the use of rationally tagged virus by revealing a high confidence NS5 interaction network in human hepatic cells. Our analysis uncovered previously unrecognized hnRNP complexes and several low-abundance fatty acid metabolism genes, which have been implicated in the viral life cycle. This study sets a new standard for investigation of host-flavivirus interactions.

  12. An interaction between human papillomavirus 16 E2 and TopBP1 is required for optimum viral DNA replication and episomal genome establishment.

    Science.gov (United States)

    Donaldson, Mary M; Mackintosh, Lorna J; Bodily, Jason M; Dornan, Edward S; Laimins, Laimonis A; Morgan, Iain M

    2012-12-01

    In human papillomavirus DNA replication, the viral protein E2 forms homodimers and binds to 12-bp palindromic DNA sequences surrounding the origin of DNA replication. Via a protein-protein interaction, it then recruits the viral helicase E1 to an A/T-rich origin of replication, whereupon a dihexamer forms, resulting in DNA replication initiation. In order to carry out DNA replication, the viral proteins must interact with host factors that are currently not all known. An attractive cellular candidate for regulating viral replication is TopBP1, a known interactor of the E2 protein. In mammalian DNA replication, TopBP1 loads DNA polymerases onto the replicative helicase after the G(1)-to-S transition, and this process is tightly cell cycle controlled. The direct interaction between E2 and TopBP1 would allow E2 to bypass this cell cycle control, resulting in DNA replication more than once per cell cycle, which is a requirement for the viral life cycle. We report here the generation of an HPV16 E2 mutant compromised in TopBP1 interaction in vivo and demonstrate that this mutant retains transcriptional activation and repression functions but has suboptimal DNA replication potential. Introduction of this mutant into a viral life cycle model results in the failure to establish viral episomes. The results present a potential new antiviral target, the E2-TopBP1 interaction, and increase our understanding of the viral life cycle, suggesting that the E2-TopBP1 interaction is essential.

  13. Longitudinal Kinetics of Cytomegalovirus-Specific T-Cell Immunity and Viral Replication in Infants With Congenital Cytomegalovirus Infection.

    Science.gov (United States)

    Chen, Sharon F; Holmes, Tyson H; Slifer, Teri; Ramachandran, Vasavi; Mackey, Sally; Hebson, Cathleen; Arvin, Ann M; Lewis, David B; Dekker, Cornelia L

    2016-03-01

    Congenital cytomegalovirus (CMV) is reported to affect up to 1% of all live births in the United States. T-cell immunity may be important for controlling CMV replication in congenital CMV-infected infants. We describe the natural history of CMV-specific T-cell evolution and CMV replication in infants with congenital CMV infection. Cytomegalovirus viral load, CMV urine culture, and CMV-specific CD4 and CD8 T-cell responses were assessed in a prospective longitudinal cohort of 51 infants with congenital CMV infection who were observed from birth to 3 years of age. We found a kinetic pattern of decreasing urinary CMV replication and increasing CMV-specific CD4 and CD8 T-cell responses during the first 3 years of life. We also found higher CMV-specific CD8 T-cell responses were associated with subsequent reduction of urine CMV viral load. For infants with congenital CMV infection, our data suggest an age-related maturation of both CMV-specific CD4 and CD8 T-cell immunity that is associated with an age-related decline in urinary CMV replication. © The Author 2014. Published by Oxford University Press on behalf of the Pediatric Infectious Diseases Society. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. Influenza A Virus Protein PA-X Contributes to Viral Growth and Suppression of the Host Antiviral and Immune Responses.

    Science.gov (United States)

    Hayashi, Tsuyoshi; MacDonald, Leslie A; Takimoto, Toru

    2015-06-01

    Influenza virus infection causes global inhibition of host protein synthesis in infected cells. This host shutoff is thought to allow viruses to escape from the host antiviral response, which restricts virus replication and spread. Although the mechanism of host shutoff is unclear, a novel viral protein expressed by ribosomal frameshifting, PA-X, was found to play a major role in influenza virus-induced host shutoff. However, little is known about the impact of PA-X expression on currently circulating influenza A virus pathogenicity and the host antiviral response. In this study, we rescued a recombinant influenza A virus, A/California/04/09 (H1N1, Cal), containing mutations at the frameshift motif in the polymerase PA gene (Cal PA-XFS). Cal PA-XFS expressed significantly less PA-X than Cal wild type (WT). Cal WT, but not Cal PA-XFS, induced degradation of host β-actin mRNA and suppressed host protein synthesis, supporting the idea that PA-X induces host shutoff via mRNA decay. Moreover, Cal WT inhibited beta interferon (IFN-β) expression and replicated more rapidly than Cal PA-XFS in human respiratory cells. Mice infected with Cal PA-XFS had significantly lower levels of viral growth and greater expression of IFN-β mRNA in their lungs than mice infected with Cal WT. Importantly, more antihemagglutinin and neutralizing antibodies were produced in Cal PA-XFS-infected mice than in Cal WT-infected mice, despite the lower level of virus replication in the lungs. Our data indicate that PA-X of the pandemic H1N1 virus has a strong impact on viral growth and the host innate and acquired immune responses to influenza virus. Virus-induced host protein shutoff is considered to be a major factor allowing viruses to evade innate and acquired immune recognition. We provide evidence that the 2009 H1N1 influenza A virus protein PA-X plays a role in virus replication and inhibition of host antiviral response by means of its host protein synthesis shutoff activity both in vitro

  15. Proficient Replication of the Yeast Genome by a Viral DNA Polymerase.

    Science.gov (United States)

    Stodola, Joseph L; Stith, Carrie M; Burgers, Peter M

    2016-05-27

    DNA replication in eukaryotic cells requires minimally three B-family DNA polymerases: Pol α, Pol δ, and Pol ϵ. Pol δ replicates and matures Okazaki fragments on the lagging strand of the replication fork. Saccharomyces cerevisiae Pol δ is a three-subunit enzyme (Pol3-Pol31-Pol32). A small C-terminal domain of the catalytic subunit Pol3 carries both iron-sulfur cluster and zinc-binding motifs, which mediate interactions with Pol31, and processive replication with the replication clamp proliferating cell nuclear antigen (PCNA), respectively. We show that the entire N-terminal domain of Pol3, containing polymerase and proofreading activities, could be effectively replaced by those from bacteriophage RB69, and could carry out chromosomal DNA replication in yeast with remarkable high fidelity, provided that adaptive mutations in the replication clamp PCNA were introduced. This result is consistent with the model that all essential interactions for DNA replication in yeast are mediated through the small C-terminal domain of Pol3. The chimeric polymerase carries out processive replication with PCNA in vitro; however, in yeast, it requires an increased involvement of the mutagenic translesion DNA polymerase ζ during DNA replication. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Viral suppression of multiple escape mutants by de novo CD8+ T cell responses in a human immunodeficiency virus-1 Infected elite suppressor

    Directory of Open Access Journals (Sweden)

    Siliciano Robert F

    2011-08-01

    Full Text Available Abstract Elite suppressors or controllers (ES are HIV-1 infected patients who maintain undetectable viral loads without treatment. While HLA-B*57-positive ES are usually infected with virus that is unmutated at CTL epitopes, a single, dominant variant containing CTL escape mutations is typically seen in plasma during chronic infection. We describe an ES who developed seven distinct and rare escape variants at an HLA-B*57-restricted Gag epitope over a five year period. Interestingly, he developed proliferative, de novo CTL responses that suppressed replication of each of these variants. These responses, in combination with low viral fitness of each variant, may contribute to sustained elite control in this ES.

  17. Long Terminal Repeat Circular DNA as Markers of Active Viral Replication of Human T Lymphotropic Virus-1 in Vivo

    Directory of Open Access Journals (Sweden)

    James M Fox

    2016-03-01

    Full Text Available Clonal expansion of human T-lymphotropic virus type-1 (HTLV-1 infected cells in vivo is well documented. Unlike human immunodeficiency virus type 1 (HIV-1, HTLV-1 plasma RNA is sparse. The contribution of the “mitotic” spread of HTLV-1 compared with infectious spread of the virus to HTLV-1 viral burden in established infection is uncertain. Since extrachromosomal long terminal repeat (LTR DNA circles are indicators of viral replication in HIV-1 carriers with undetectable plasma HIV RNA, we hypothesised that HTLV-1 LTR circles could indicate reverse transcriptase (RT usage and infectious activity. 1LTR and 2LTR DNA circles were measured in HTLV-1 cell lines and peripheral blood mononuclear cells (PBMC of asymptomatic carriers (ACs and patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP or adult T cell leukaemia/lymphoma (ATLL. 1LTR DNA circles were detected in 14/20 patients at a mean of 1.38/100 PBMC but did not differentiate disease status nor correlate with HTLV-1 DNA copies. 2LTR DNA circles were detected in 30/31 patients and at higher concentrations in patients with HTLV-1-associated diseases, independent of HTLV-1 DNA load. In an incident case the 2LTR DNA circle concentration increased 2.1 fold at the onset of HAM/TSP compared to baseline. Detectable and fluctuating levels of HTLV-1 DNA circles in patients indicate viral RT usage and virus replication. Our results indicate HTLV-1 viral replication capacity is maintained in chronic infection and may be associated with disease onset.

  18. Adeno-Associated Viral Vector-Induced Overexpression of Neuropeptide Y Y2 Receptors in the Hippocampus Suppresses Seizures

    Science.gov (United States)

    Woldbye, David P. D.; Angehagen, Mikael; Gotzsche, Casper R.; Elbrond-Bek, Heidi; Sorensen, Andreas T.; Christiansen, Soren H.; Olesen, Mikkel V.; Nikitidou, Litsa; Hansen, Thomas v. O.; Kanter-Schlifke, Irene; Kokaia, Merab

    2010-01-01

    Gene therapy using recombinant adeno-associated viral vectors overexpressing neuropeptide Y in the hippocampus exerts seizure-suppressant effects in rodent epilepsy models and is currently considered for clinical application in patients with intractable mesial temporal lobe epilepsy. Seizure suppression by neuropeptide Y in the hippocampus is…

  19. Zinc Salts Block Hepatitis E Virus Replication by Inhibiting the Activity of Viral RNA-Dependent RNA Polymerase.

    Science.gov (United States)

    Kaushik, Nidhi; Subramani, Chandru; Anang, Saumya; Muthumohan, Rajagopalan; Shalimar; Nayak, Baibaswata; Ranjith-Kumar, C T; Surjit, Milan

    2017-11-01

    Hepatitis E virus (HEV) causes an acute, self-limiting hepatitis in healthy individuals and leads to chronic disease in immunocompromised individuals. HEV infection in pregnant women results in a more severe outcome, with the mortality rate going up to 30%. Though the virus usually causes sporadic infection, epidemics have been reported in developing and resource-starved countries. No specific antiviral exists against HEV. A combination of interferon and ribavirin therapy has been used to control the disease with some success. Zinc is an essential micronutrient that plays crucial roles in multiple cellular processes. Zinc salts are known to be effective in reducing infections caused by few viruses. Here, we investigated the effect of zinc salts on HEV replication. In a human hepatoma cell (Huh7) culture model, zinc salts inhibited the replication of genotype 1 (g-1) and g-3 HEV replicons and g-1 HEV infectious genomic RNA in a dose-dependent manner. Analysis of a replication-defective mutant of g-1 HEV genomic RNA under similar conditions ruled out the possibility of zinc salts acting on replication-independent processes. An ORF4-Huh7 cell line-based infection model of g-1 HEV further confirmed the above observations. Zinc salts did not show any effect on the entry of g-1 HEV into the host cell. Furthermore, our data reveal that zinc salts directly inhibit the activity of viral RNA-dependent RNA polymerase (RdRp), leading to inhibition of viral replication. Taken together, these studies unravel the ability of zinc salts in inhibiting HEV replication, suggesting their possible therapeutic value in controlling HEV infection. IMPORTANCE Hepatitis E virus (HEV) is a public health concern in resource-starved countries due to frequent outbreaks. It is also emerging as a health concern in developed countries owing to its ability to cause acute and chronic infection in organ transplant and immunocompromised individuals. Although antivirals such as ribavirin have been used

  20. Relationship Dynamics and Partner Beliefs About Viral Suppression: A Longitudinal Study of Male Couples Living with HIV/AIDS (The Duo Project).

    Science.gov (United States)

    Conroy, Amy A; Gamarel, Kristi E; Neilands, Torsten B; Dilworth, Samantha E; Darbes, Lynae A; Johnson, Mallory O

    2016-07-01

    Accurate beliefs about partners' viral suppression are important for HIV prevention and care. We fit multilevel mixed effects logistic regression models to examine associations between partners' viral suppression beliefs and objective HIV RNA viral load tests, and whether relationship dynamics were associated with accurate viral suppression beliefs over time. Male couples (N = 266 couples) with at least one HIV-positive partner on antiretroviral therapy completed five assessments over 2 years. Half of the 407 HIV-positive partners were virally suppressed. Of the 40 % who had inaccurate viral load beliefs, 80 % assumed their partner was suppressed. The odds of having accurate viral load beliefs decreased over time (OR = 0.83; p = 0.042). Within-couple differences in dyadic adjustment (OR = 0.66; p Couple-based approaches are warranted to improve knowledge of partners' viral load.

  1. Macrophage activation induced by Brucella DNA suppresses bacterial intracellular replication via enhancing NO production.

    Science.gov (United States)

    Liu, Ning; Wang, Lin; Sun, Changjiang; Yang, Li; Tang, Bin; Sun, Wanchun; Peng, Qisheng

    2015-12-01

    Brucella DNA can be sensed by TLR9 on endosomal membrane and by cytosolic AIM2-inflammasome to induce proinflammatory cytokine production that contributes to partially activate innate immunity. Additionally, Brucella DNA has been identified to be able to act as a major bacterial component to induce type I IFN. However, the role of Brucella DNA in Brucella intracellular growth remains unknown. Here, we showed that stimulation with Brucella DNA promote macrophage activation in TLR9-dependent manner. Activated macrophages can suppresses wild type Brucella intracellular replication at early stage of infection via enhancing NO production. We also reported that activated macrophage promotes bactericidal function of macrophages infected with VirB-deficient Brucella at the early or late stage of infection. This study uncovers a novel function of Brucella DNA, which can help us further elucidate the mechanism of Brucella intracellular survival. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Trends in Racial and Ethnic Disparities in Antiretroviral Therapy Prescription and Viral Suppression in the United States, 2009-2013.

    Science.gov (United States)

    Beer, Linda; Bradley, Heather; Mattson, Christine L; Johnson, Christopher H; Hoots, Brooke; Shouse, Roy L

    2016-12-01

    To examine trends in racial/ethnic disparities in antiretroviral therapy (ART) prescription and viral suppression among HIV-infected persons in care, overall and among men who have sex with men (MSM), from 2009 to 2013. The Medical Monitoring Project (MMP) is a complex sample survey of HIV-infected adults receiving medical care in the United States. We used weighted interview and medical record data collected June 2009-May 2014 to estimate the prevalence of ART prescription and viral suppression among racial/ethnic groups overall and among MSM. We found significant increases in ART prescription and viral suppression among all racial/ethnic groups from 2009 to 2013, both overall and among MSM. By 2013, overall and among MSM, the Hispanic-white disparity in ART prescription was nonexistent, and the black-white disparity was not significant after accounting for differences between blacks and whites in age and length of HIV diagnosis. Despite reductions in racial/ethnic disparities in viral suppression over the time period, significant disparities remained among the total population, even after adjusting for differences in racial/ethnic group characteristics. Encouragingly, however, there was no significant Hispanic-white disparity in viral suppression among MSM by 2013. Despite significant improvements in ART prescription and viral suppression in recent years, racial and ethnic disparities persist, particularly for black persons. If the United States is to achieve the National HIV/AIDS Strategy goal of reducing HIV-related health disparities, continued efforts to accelerate the rate of improvement in ART prescription and viral suppression among Hispanic and black persons may need to be prioritized.

  3. Regulation of Viral Replication, Apoptosis and Pro-Inflammatory Responses by 17-AAG during Chikungunya Virus Infection in Macrophages

    Directory of Open Access Journals (Sweden)

    Tapas K. Nayak

    2017-01-01

    Full Text Available Chikungunya virus (CHIKV infection has re-emerged as a major public health concern due to its recent worldwide epidemics and lack of control measures. Although CHIKV is known to infect macrophages, regulation of CHIKV replication, apoptosis and immune responses towards macrophages are not well understood. Accordingly, the Raw264.7 cells, a mouse macrophage cell line, were infected with CHIKV and viral replication as well as new viral progeny release was assessed by flow cytometry and plaque assay, respectively. Moreover, host immune modulation and apoptosis were studied through flow cytometry, Western blot and ELISA. Our current findings suggest that expression of CHIKV proteins were maximum at 8 hpi and the release of new viral progenies were remarkably increased around 12 hpi. The induction of Annexin V binding, cleaved caspase-3, cleaved caspase-9 and cleaved caspase-8 in CHIKV infected macrophages suggests activation of apoptosis through both intrinsic and extrinsic pathways. The pro-inflammatory mediators (TNF and IL-6 MHC-I/II and B7.2 (CD86 were also up-regulated during infection over time. Further, 17-AAG, a potential HSP90 inhibitor, was found to regulate CHIKV infection, apoptosis and pro-inflammatory cytokine/chemokine productions of host macrophages significantly. Hence, the present findings might bring new insight into the therapeutic implication in CHIKV disease biology.

  4. Regulation of Viral Replication, Apoptosis and Pro-Inflammatory Responses by 17-AAG during Chikungunya Virus Infection in Macrophages.

    Science.gov (United States)

    Nayak, Tapas K; Mamidi, Prabhudutta; Kumar, Abhishek; Singh, Laishram Pradeep K; Sahoo, Subhransu S; Chattopadhyay, Soma; Chattopadhyay, Subhasis

    2017-01-06

    Chikungunya virus (CHIKV) infection has re-emerged as a major public health concern due to its recent worldwide epidemics and lack of control measures. Although CHIKV is known to infect macrophages, regulation of CHIKV replication, apoptosis and immune responses towards macrophages are not well understood. Accordingly, the Raw264.7 cells, a mouse macrophage cell line, were infected with CHIKV and viral replication as well as new viral progeny release was assessed by flow cytometry and plaque assay, respectively. Moreover, host immune modulation and apoptosis were studied through flow cytometry, Western blot and ELISA. Our current findings suggest that expression of CHIKV proteins were maximum at 8 hpi and the release of new viral progenies were remarkably increased around 12 hpi. The induction of Annexin V binding, cleaved caspase-3, cleaved caspase-9 and cleaved caspase-8 in CHIKV infected macrophages suggests activation of apoptosis through both intrinsic and extrinsic pathways. The pro-inflammatory mediators (TNF and IL-6) MHC-I/II and B7.2 (CD86) were also up-regulated during infection over time. Further, 17-AAG, a potential HSP90 inhibitor, was found to regulate CHIKV infection, apoptosis and pro-inflammatory cytokine/chemokine productions of host macrophages significantly. Hence, the present findings might bring new insight into the therapeutic implication in CHIKV disease biology.

  5. Genome-wide analysis of protein-protein interactions and involvement of viral proteins in SARS-CoV replication.

    Directory of Open Access Journals (Sweden)

    Ji'an Pan

    Full Text Available Analyses of viral protein-protein interactions are an important step to understand viral protein functions and their underlying molecular mechanisms. In this study, we adopted a mammalian two-hybrid system to screen the genome-wide intraviral protein-protein interactions of SARS coronavirus (SARS-CoV and therefrom revealed a number of novel interactions which could be partly confirmed by in vitro biochemical assays. Three pairs of the interactions identified were detected in both directions: non-structural protein (nsp 10 and nsp14, nsp10 and nsp16, and nsp7 and nsp8. The interactions between the multifunctional nsp10 and nsp14 or nsp16, which are the unique proteins found in the members of Nidovirales with large RNA genomes including coronaviruses and toroviruses, may have important implication for the mechanisms of replication/transcription complex assembly and functions of these viruses. Using a SARS-CoV replicon expressing a luciferase reporter under the control of a transcription regulating sequence, it has been shown that several viral proteins (N, X and SUD domains of nsp3, and nsp12 provided in trans stimulated the replicon reporter activity, indicating that these proteins may regulate coronavirus replication and transcription. Collectively, our findings provide a basis and platform for further characterization of the functions and mechanisms of coronavirus proteins.

  6. Secondary mutations in viruses resistant to HIV-1 integrase inhibitors that restore viral infectivity and replication kinetics.

    Science.gov (United States)

    Nakahara, Koichiro; Wakasa-Morimoto, Chiaki; Kobayashi, Masanori; Miki, Shigeru; Noshi, Takeshi; Seki, Takahiro; Kanamori-Koyama, Mikiko; Kawauchi, Shinobu; Suyama, Akemi; Fujishita, Toshio; Yoshinaga, Tomokazu; Garvey, Edward P; Johns, Brian A; Foster, Scott A; Underwood, Mark R; Sato, Akihiko; Fujiwara, Tamio

    2009-02-01

    Passage of HIV-1 in the presence of integrase inhibitors (INIs) generates resistant viruses that have mutations in the integrase region. Integrase-resistant mutations Q148K and Q148R were identified as primary mutations with the passage of HIV-1 IIIB in the presence of INIs S-1360 or S/GSK-364735, respectively. Secondary amino acid substitutions E138K or G140S were observed when passage with INI was continued. The role of these mutations was investigated with molecular clones. Relative to Q148K alone, Q148K/E138K had 2- and >6-fold increases in resistance to S-1360 and S/GSK-364735, respectively, and the double mutant had slightly better infectivity and replication kinetics. In contrast, Q148K/G140S and Q148R/E138K had nearly equivalent or slightly reduced fold resistance to the INI compared with their respective Q148 primary mutants, and had increases in infectivity and replication kinetics. Recovery of these surrogates of viral fitness coincided with the recovery of integration efficiency of viral DNA into the host cell chromosome for these double mutants. These data show that recovery of viral integration efficiency can be an important factor for the emergence and maintenance of INI-resistant mutations.

  7. Doubly Spliced RNA of Hepatitis B Virus Suppresses Viral Transcription via TATA-Binding Protein and Induces Stress Granule Assembly.

    Science.gov (United States)

    Tsai, Kuen-Nan; Chong, Chin-Liew; Chou, Yu-Chi; Huang, Chien-Chiao; Wang, Yi-Ling; Wang, Shao-Win; Chen, Mong-Liang; Chen, Chun-Hong; Chang, Chungming

    2015-11-01

    genotypes. Using cultured human hepatoma cells as a model of HBV infection, we found that the expression of 2.2DS-RNA caused a decrease in HBV replication. In cultured cells, the ectopic expression of 2.2DS-RNA obviously reduced the intracellular levels of HBV mRNAs. Our analysis of the 2.2DS-RNA-mediated suppression of viral RNA expression showed that 2.2DS-RNA inhibited transcription via binding to the TATA-binding protein and stress granule proteins. Our findings suggest that the 2.2DS-RNA acts as a suppressive noncoding RNA that modulates HBV replication, which may in turn influence the development of chronic hepatitis B. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  8. Viral replication in excised fin tissues (VREFT) corresponds with prior exposure of Pacific herring, Clupea pallasii (Valenciennes), to viral haemorrhagic septicaemia virus (VHSV)

    Science.gov (United States)

    Grady, C.A.; Gregg, J.L.; Wade, R.M.; Winton, J.R.; Hershberger, P.K.

    2011-01-01

    Procedures for a viral replication in excised fin tissue (VREFT) assay were adapted to Pacific herring, Clupea pallasii, and optimized both to reduce processing time and to provide the greatest resolution between na??ve herring and those previously exposed to viral haemorrhagic septicaemia virus (VHSV), Genogroup IVa. The optimized procedures included removal of the left pectoral fin from a euthanized fish, inoculation of the fin with >105 plaque-forming units (PFU) mL-1 VHSV for 1 h, rinsing the fin in fresh medium six times to remove unadsorbed virions, incubation of the fin in fresh medium for 4 days and enumeration of the viral titre in a sample of the incubation medium by plaque assay. The optimized VREFT assay was effective at identifying the prior exposure history of laboratory-reared Pacific herring to VHSV. The geometric mean VREFT value was significantly greater (P PFU mL-1) than among groups that survived exposure to VHSV (1.0-2.9 ?? 102 PFU mL-1); additionally, the proportion of cultures with no detectable virus was significantly greater (P = 0.0002) among fish that survived exposure to VHSV (39-47%) than among na??ve fish (3.3%). The optimized VREFT assay demonstrates promise for identifying VHSV exposure history and forecasting disease potential in populations of wild Pacific herring. ?? 2010 Blackwell Publishing Ltd.

  9. Viral replication in excised fin tissues (VREFT) corresponds with prior exposure of Pacific herring, Clupea pallasii (Valenciennes), to viral haemorrhagic septicaemia virus (VHSV)

    Science.gov (United States)

    Grady, C.A.; Gregg, J.L.; Wade, R.M.; Winton, J.R.; Hershberger, P.K.

    2011-01-01

    Procedures for a viral replication in excised fin tissue (VREFT) assay were adapted to Pacific herring, Clupea pallasii, and optimized both to reduce processing time and to provide the greatest resolution between na??ve herring and those previously exposed to viral haemorrhagic septicaemia virus (VHSV), Genogroup IVa. The optimized procedures included removal of the left pectoral fin from a euthanized fish, inoculation of the fin with >105 plaque-forming units (PFU) mL-1 VHSV for 1 h, rinsing the fin in fresh medium six times to remove unadsorbed virions, incubation of the fin in fresh medium for 4 days and enumeration of the viral titre in a sample of the incubation medium by plaque assay. The optimized VREFT assay was effective at identifying the prior exposure history of laboratory-reared Pacific herring to VHSV. The geometric mean VREFT value was significantly greater (P < 0.01) among na??ve herring (1.2 ?? 103 PFU mL-1) than among groups that survived exposure to VHSV (1.0-2.9 ?? 102 PFU mL-1); additionally, the proportion of cultures with no detectable virus was significantly greater (P = 0.0002) among fish that survived exposure to VHSV (39-47%) than among na??ve fish (3.3%). The optimized VREFT assay demonstrates promise for identifying VHSV exposure history and forecasting disease potential in populations of wild Pacific herring. ?? 2010 Blackwell Publishing Ltd.

  10. Antiretroviral Therapy Use, Medication Adherence, and Viral Suppression Among PLWHA with Panic Symptoms.

    Science.gov (United States)

    Sam, Tanyka Suzanne; Hutton, Heidi E; Lau, Bryan; McCaul, Mary E; Keruly, Jeanne; Moore, Richard; Chander, Geetanjali

    2015-11-01

    Panic symptoms are prevalent among PLWHAs, yet few studies have examined their relationship with HIV outcomes. Using data from an observational cohort study in Baltimore, MD, we examined the association between panic symptoms and antiretroviral therapy (ART) use, medication adherence, and viral suppression. Data were analyzed using generalized estimating equations and adjusted for age, sex, race/ethnicity, cocaine and/or heroin use, clinic enrollment time, alcohol use, and depressive symptoms. Between June 2010 and September 2012, 1195 individuals participated in 2080 audio computer assisted interviews; 9.9 % (n = 118) of individuals endorsed current panic symptoms. In multivariate analysis, panic symptoms were associated with decreased ART use (IRR 0.94; p = 0.05). Panic symptoms were neither associated with medication adherence nor viral suppression. These findings were independent of depressive symptoms and substance use. Panic symptoms are under-recognized in primary care settings and present an important barrier to ART use. Further studies investigating the reasons for this association are needed.

  11. Molecular biology of human herpesvirus 8: novel functions and virus-host interactions implicated in viral pathogenesis and replication.

    Science.gov (United States)

    Cousins, Emily; Nicholas, John

    2014-01-01

    Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), is the second identified human gammaherpesvirus. Like its relative Epstein-Barr virus, HHV-8 is linked to B-cell tumors, specifically primary effusion lymphoma and multicentric Castleman's disease, in addition to endothelial-derived KS. HHV-8 is unusual in its possession of a plethora of "accessory" genes and encoded proteins in addition to the core, conserved herpesvirus and gammaherpesvirus genes that are necessary for basic biological functions of these viruses. The HHV-8 accessory proteins specify not only activities deducible from their cellular protein homologies but also novel, unsuspected activities that have revealed new mechanisms of virus-host interaction that serve virus replication or latency and may contribute to the development and progression of virus-associated neoplasia. These proteins include viral interleukin-6 (vIL-6), viral chemokines (vCCLs), viral G protein-coupled receptor (vGPCR), viral interferon regulatory factors (vIRFs), and viral antiapoptotic proteins homologous to FLICE (FADD-like IL-1β converting enzyme)-inhibitory protein (FLIP) and survivin. Other HHV-8 proteins, such as signaling membrane receptors encoded by open reading frames K1 and K15, also interact with host mechanisms in unique ways and have been implicated in viral pathogenesis. Additionally, a set of micro-RNAs encoded by HHV-8 appear to modulate expression of multiple host proteins to provide conditions conducive to virus persistence within the host and could also contribute to HHV-8-induced neoplasia. Here, we review the molecular biology underlying these novel virus-host interactions and their potential roles in both virus biology and virus-associated disease.

  12. Mechanisms of CD8+ T cell-mediated suppression of HIV/SIV replication.

    Science.gov (United States)

    McBrien, Julia Bergild; Kumar, Nitasha A; Silvestri, Guido

    2018-02-10

    In this article, we summarize the role of CD8 + T cells during natural and antiretroviral therapy (ART)-treated HIV and SIV infections, discuss the mechanisms responsible for their suppressive activity, and review the rationale for CD8 + T cell-based HIV cure strategies. Evidence suggests that CD8 + T cells are involved in the control of virus replication during HIV and SIV infections. During early HIV infection, the cytolytic activity of CD8 + T cells is responsible for control of viremia. However, it has been proposed that CD8 + T cells also use non-cytolytic mechanisms to control SIV infection. More recently, CD8 + T cells were shown to be required to fully suppress virus production in ART-treated SIV-infected macaques, suggesting that CD8 + T cells are involved in the control of virus transcription in latently infected cells that persist under ART. A better understanding of the complex antiviral activities of CD8 + T cells during HIV/SIV infection will pave the way for immune interventions aimed at harnessing these functions to target the HIV reservoir. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Conserved elements within the genome of foot-and-mouth disease virus; their influence on viral replication

    DEFF Research Database (Denmark)

    Kjær, Jonas

    for the development of anti-viral agents. SHAPE analysis of the entire FMDV genome (Poulsen, 2015) has identified three conserved RNA structures within the coding regions for 2B, 3C and 3D (RNA-dependent RNA polymerase) which might have an important role in virus replication. The FMDV 2A peptide, another conserved...... a distinct codon bias. Remarkably, this bias matches the codon bias observed within naturally occurring FMDV strains. Interestingly, the codons selected are different for P17 and P19. Residue P17 is preferentially encoded by CCU while P19 is preferentially encoded by CCC. However, a single prolyl......-tRNA species recognizes both of these two codons in cattle and pigs, which are the major hosts for FMDV, and suggests a role for the RNA sequence itself. Manuscript 3 examines the influence of three conserved RNA structures within the genome of FMDV on viral protein synthesis and virus viability. Poulsen...

  14. miR-101 suppresses HBV replication and expression by targeting FOXO1 in hepatoma carcinoma cell lines.

    Science.gov (United States)

    Wang, Yanjing; Tian, Hui

    2017-05-20

    microRNAs (miRNAs) have been identified to participate in the progression of cancers and in the infection of viruses. miR-101 expression has been found to be suppressed by HBV, however, the regulatory relationship between miR-101 and HBV replication remains elusive. In this report, miR-101 was significantly downregulated in HepG2.2.15 cells with HBV expression. miR-101 overexpression dramatically suppressed HBV replication and expression. Oppositely, overexpression of FOXO1 significantly promoted HBV replication and expression. Moreover, luciferase reporter analysis, qRT-PCR analysis and western blot assay confirmed that FOXO1 was a functional target of miR-101. Furthermore, restored FOXO1 expression abolished the inhibitory effect of miR-101 overexpression on HBV replication and expression in HepG2.2.15 cells. Our data suggested that miR-101 suppressed HBV replication and expression partially by targeting FOXO1, providing new insights into the molecular mechanisms of miR-101 in HBV-host interactions and a promising therapeutic target for HBV replication. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Monitoring the determinants of efficient viral replication using Classical Swine Fever Virus-reporter replicons

    DEFF Research Database (Denmark)

    Risager, Peter Christian; Everett, Helen; Crooke, Helen

    2012-01-01

    Classical swine fever virus (CSFV) is the etiological agent of the severe porcine disease, classical swine fever. Unraveling the molecular determinants of efficient replication is crucial for gaining improved knowledge of the pathogenic features of this virus. Monitoring the replication competence...... of the CSFV genome within cells can be achieved using autonomously replicating constructs (replicons) containing a reporter gene that expresses a readily quantifiable enzyme. Here, a newly implemented cloning technique was applied to genome modification of the fulllength CSFV cDNA previously inserted...... proteins considered non-essential for RNA replication were constructed and these deletions were replaced with an in-frame insertion of the Renilla luciferase (Rluc) sequence. RNA transcripts from these replicons should be translated as a single functional open reading frame. Full-genome cDNAs (~10-12,3 kb...

  16. Host–Pathogen Interactions in Measles Virus Replication and Anti-Viral Immunity

    Directory of Open Access Journals (Sweden)

    Yanliang Jiang

    2016-11-01

    Full Text Available The measles virus (MeV is a contagious pathogenic RNA virus of the family Paramyxoviridae, genus Morbillivirus, that can cause serious symptoms and even fetal complications. Here, we summarize current molecular advances in MeV research, and emphasize the connection between host cells and MeV replication. Although measles has reemerged recently, the potential for its eradication is promising with significant progress in our understanding of the molecular mechanisms of its replication and host-pathogen interactions.

  17. Requirement of the N-terminal residues of human cytomegalovirus UL112-113 proteins for viral growth and oriLyt-dependent DNA replication.

    Science.gov (United States)

    Kim, Young-Eui; Park, Mi Young; Kang, Kyeong Jin; Han, Tae Hee; Lee, Chan Hee; Ahn, Jin-Hyun

    2015-08-01

    The UL112-113 region of the human cytomegalovirus (HCMV) genome encodes four phosphoproteins of 34, 43, 50, and 84 kDa that promote viral DNA replication. Co-transfection assays have demonstrated that self-interaction of these proteins via the shared N-termini is necessary for their intranuclear distribution as foci and for the efficient relocation of a viral DNA polymerase processivity factor (UL44) to the viral replication sites. However, the requirement of UL112-113 N-terminal residues for viral growth and DNA replication has not been fully elucidated. Here, we investigated the effect of deletion of the N-terminal regions of UL112-113 proteins on viral growth and oriLyt-dependent DNA replication. A deletion of the entire UL112 region or the region encoding the 25 N-terminal amino-acid residues from the HCMV (Towne strain) bacmid impaired viral growth in bacmid-transfected human fibroblast cells, indicating their requirement for viral growth. In co-immunoprecipitation assays using the genomic gene expressing the four UL112-113 proteins together, the 25 N-terminal amino-acid residues were found to be necessary for stable expression of UL112-113 proteins and their self-interaction. These residues were also required for efficient binding to and relocation of UL44, but not for interaction with IE2, an origin-binding transcription factor. In co-transfection/replication assays, replication of the oriLyt-containing plasmid was promoted by expression of intact UL112-113 proteins, but not by the expression of 25-amino-acid residue-deleted proteins. Our results demonstrate that the 25 N-terminal amino-acid residues of UL112-113 proteins that mediate self-interaction contribute to viral growth by promoting their binding to UL44 and the initiation of oriLyt-dependent DNA replication.

  18. Replication-competent infectious hepatitis B virus vectors carrying substantially sized transgenes by redesigned viral polymerase translation.

    Science.gov (United States)

    Wang, Zihua; Wu, Li; Cheng, Xin; Liu, Shizhu; Li, Baosheng; Li, Haijun; Kang, Fubiao; Wang, Junping; Xia, Huan; Ping, Caiyan; Nassal, Michael; Sun, Dianxing

    2013-01-01

    Viral vectors are engineered virus variants able to deliver nonviral genetic information into cells, usually by the same routes as the parental viruses. For several virus families, replication-competent vectors carrying reporter genes have become invaluable tools for easy and quantitative monitoring of replication and infection, and thus also for identifying antivirals and virus susceptible cells. For hepatitis B virus (HBV), a small enveloped DNA virus causing B-type hepatitis, such vectors are not available because insertions into its tiny 3.2 kb genome almost inevitably affect essential replication elements. HBV replicates by reverse transcription of the pregenomic (pg) RNA which is also required as bicistronic mRNA for the capsid (core) protein and the reverse transcriptase (Pol); their open reading frames (ORFs) overlap by some 150 basepairs. Translation of the downstream Pol ORF does not involve a conventional internal ribosome entry site (IRES). We reasoned that duplicating the overlap region and providing artificial IRES control for translation of both Pol and an in-between inserted transgene might yield a functional tricistronic pgRNA, without interfering with envelope protein expression. As IRESs we used a 22 nucleotide element termed Rbm3 IRES to minimize genome size increase. Model plasmids confirmed its activity even in tricistronic arrangements. Analogous plasmids for complete HBV genomes carrying 399 bp and 720 bp transgenes for blasticidin resistance (BsdR) and humanized Renilla green fluorescent protein (hrGFP) produced core and envelope proteins like wild-type HBV; while the hrGFP vector replicated poorly, the BsdR vector generated around 40% as much replicative DNA as wild-type HBV. Both vectors, however, formed enveloped virions which were infectious for HBV-susceptible HepaRG cells. Because numerous reporter and effector genes with sizes of around 500 bp or less are available, the new HBV vectors should become highly useful tools to better

  19. Replication-competent infectious hepatitis B virus vectors carrying substantially sized transgenes by redesigned viral polymerase translation.

    Directory of Open Access Journals (Sweden)

    Zihua Wang

    Full Text Available Viral vectors are engineered virus variants able to deliver nonviral genetic information into cells, usually by the same routes as the parental viruses. For several virus families, replication-competent vectors carrying reporter genes have become invaluable tools for easy and quantitative monitoring of replication and infection, and thus also for identifying antivirals and virus susceptible cells. For hepatitis B virus (HBV, a small enveloped DNA virus causing B-type hepatitis, such vectors are not available because insertions into its tiny 3.2 kb genome almost inevitably affect essential replication elements. HBV replicates by reverse transcription of the pregenomic (pg RNA which is also required as bicistronic mRNA for the capsid (core protein and the reverse transcriptase (Pol; their open reading frames (ORFs overlap by some 150 basepairs. Translation of the downstream Pol ORF does not involve a conventional internal ribosome entry site (IRES. We reasoned that duplicating the overlap region and providing artificial IRES control for translation of both Pol and an in-between inserted transgene might yield a functional tricistronic pgRNA, without interfering with envelope protein expression. As IRESs we used a 22 nucleotide element termed Rbm3 IRES to minimize genome size increase. Model plasmids confirmed its activity even in tricistronic arrangements. Analogous plasmids for complete HBV genomes carrying 399 bp and 720 bp transgenes for blasticidin resistance (BsdR and humanized Renilla green fluorescent protein (hrGFP produced core and envelope proteins like wild-type HBV; while the hrGFP vector replicated poorly, the BsdR vector generated around 40% as much replicative DNA as wild-type HBV. Both vectors, however, formed enveloped virions which were infectious for HBV-susceptible HepaRG cells. Because numerous reporter and effector genes with sizes of around 500 bp or less are available, the new HBV vectors should become highly useful tools to

  20. Remission from Kaposi's sarcoma on HAART is associated with suppression of HIV replication and is independent of protease inhibitor therapy.

    Science.gov (United States)

    Martinez, V; Caumes, E; Gambotti, L; Ittah, H; Morini, J-P; Deleuze, J; Gorin, I; Katlama, C; Bricaire, F; Dupin, N

    2006-04-10

    Highly active antiretroviral therapy (HAART) reduces the incidence and improves the prognosis of Kaposi's sarcoma (KS). This study was designed to identify factors associated with KS clinical responses in HIV-infected patients during HAART. We reviewed the files of 138 HIV-1-infected patients with KS. Epidemiologic and HIV-related clinical and biological parameters were recorded at KS diagnosis (baseline) and every 6 months thereafter. In a subset of 73 antiretroviral-naive patients, we compared the clinical outcome of KS according to the use or nonuse of protease inhibitors (PI). After 6 months of follow-up, KS remission was more frequent in patients who were naive of HAART and who were at ACTG stage S0 at baseline (P = 0.03 and 0.02). Undetectable HIV viral load was strongly associated with KS remission (Ptime points), while CD4 cell count was not. Among the 73 antiretroviral-naive patients at baseline, and who were studied for 24 months, KS outcome did not differ between patients who were prescribed PI-containing and PI-sparing regimens. Intercurrent multicentric Castleman's disease was associated with poor outcome after 60 months of follow-up (P< or = 0.0001). Fourteen deaths occurred after a median follow-up of 37.5 months, eight of which were KS related. Suppression of HIV replication appears to be crucial to control KS. Non-PI-based regimens were equivalent to PI-based regimens as regards the clinical and virological outcome of antiretroviral-naive HIV-infected patients with KS.

  1. Type I Interferon Induced Epigenetic Regulation of Macrophages Suppresses Innate and Adaptive Immunity in Acute Respiratory Viral Infection.

    Directory of Open Access Journals (Sweden)

    Danielle N Kroetz

    2015-12-01

    Full Text Available Influenza A virus (IAV is an airborne pathogen that causes significant morbidity and mortality each year. Macrophages (Mϕ are the first immune population to encounter IAV virions in the lungs and are required to control infection. In the present study, we explored the mechanism by which cytokine signaling regulates the phenotype and function of Mϕ via epigenetic modification of chromatin. We have found that type I interferon (IFN-I potently upregulates the lysine methyltransferase Setdb2 in murine and human Mϕ, and in turn Setdb2 regulates Mϕ-mediated immunity in response to IAV. The induction of Setdb2 by IFN-I was significantly impaired upon inhibition of the JAK-STAT signaling cascade, and chromatin immunoprecipitation revealed that both STAT1 and interferon regulatory factor 7 bind upstream of the transcription start site to induce expression. The generation of Setdb2LacZ reporter mice revealed that IAV infection results in systemic upregulation of Setdb2 in myeloid cells. In the lungs, alveolar Mϕ expressed the highest level of Setdb2, with greater than 70% lacZ positive on day 4 post-infection. Silencing Setdb2 activity in Mϕ in vivo enhanced survival in lethal IAV infection. Enhanced host protection correlated with an amplified antiviral response and less obstruction to the airways. By tri-methylating H3K9, Setdb2 silenced the transcription of Mx1 and Isg15, antiviral effectors that inhibit IAV replication. Accordingly, a reduced viral load in knockout mice on day 8 post-infection was linked to elevated Isg15 and Mx1 transcript in the lungs. In addition, Setdb2 suppressed the expression of a large number of other genes with proinflammatory or immunomodulatory function. This included Ccl2, a chemokine that signals through CCR2 to regulate monocyte recruitment to infectious sites. Consistently, knockout mice produced more CCL2 upon IAV infection and this correlated with a 2-fold increase in the number of inflammatory monocytes and

  2. Why Human Papillomaviruses Activate the DNA Damage Response (DDR) and How Cellular and Viral Replication Persists in the Presence of DDR Signaling.

    Science.gov (United States)

    Bristol, Molly L; Das, Dipon; Morgan, Iain M

    2017-09-21

    Human papillomaviruses (HPV) require the activation of the DNA damage response (DDR) in order to undergo a successful life cycle. This activation presents a challenge for the virus and the infected cell: how does viral and host replication proceed in the presence of a DDR that ordinarily arrests replication; and how do HPV16 infected cells retain the ability to proliferate in the presence of a DDR that ordinarily arrests the cell cycle? This raises a further question: why do HPV activate the DDR? The answers to these questions are only partially understood; a full understanding could identify novel therapeutic strategies to target HPV cancers. Here, we propose that the rapid replication of an 8 kb double stranded circular genome during infection creates aberrant DNA structures that attract and activate DDR proteins. Therefore, HPV replication in the presence of an active DDR is a necessity for a successful viral life cycle in order to resolve these DNA structures on viral genomes; without an active DDR, successful replication of the viral genome would not proceed. We discuss the essential role of TopBP1 in this process and also how viral and cellular replication proceeds in HPV infected cells in the presence of DDR signals.

  3. Viral replication under combination antiretroviral therapy: A comparison of four different regimens

    NARCIS (Netherlands)

    Ghani, Azra C.; Ferguson, Neil M.; Fraser, Christophe; Donnelly, Christl A.; Danner, Sven; Reiss, Peter; Lange, Joep; Goudsmit, Jaap; Anderson, Roy M.; de Wolf, Frank

    2002-01-01

    A mathematical model of the interaction among CD4(+) T-cells, HIV-1, and antiretroviral drugs was fitted to the viral load decline following initiation of combination therapy to estimate differences in the residual reproductive capacity of virus (R-0) in the average patient in each group. Four

  4. Gag sequence variation in a human immunodeficiency virus type 1 transmission cluster influences viral replication fitness

    NARCIS (Netherlands)

    Gijsbers, Esther F.; van Nuenen, Ad C.; Schuitemaker, Hanneke; Kootstra, Neeltje A.

    2013-01-01

    Three men from a proven homosexual human immunodeficiency virus type 1 (HIV-1) transmission cluster showed large variation in their clinical course of infection. To evaluate the effect of evolution of the same viral variant in these three patients, we analysed sequence variation in the capsid

  5. MicroRNA-33 promotes the replicative senescence of mouse embryonic fibroblasts by suppressing CDK6

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Shun; Huang, Haijiao; Li, Nanhong; Zhang, Bing; Jia, Yubin; Yang, Yukun; Yuan, Yuan; Xiong, Xing-dong; Wang, Dengchuan; Zheng, Hui-ling [Institute of Aging Research, Guangdong Medical University, Dongguan (China); Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Dongguan (China); Institute of Biochemistry & Molecular Biology, Guangdong Medical University, Zhanjiang (China); Liu, Xinguang, E-mail: xgliu64@126.com [Institute of Aging Research, Guangdong Medical University, Dongguan (China); Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Dongguan (China); Institute of Biochemistry & Molecular Biology, Guangdong Medical University, Zhanjiang (China)

    2016-05-13

    MicroRNAs are a large class of tiny noncoding RNAs, which have emerged as critical regulators of gene expression, and thus are involved in multiple cellular processes, including cellular senescence. MicroRNA-33 has previously been established to exert crucial effect on cell proliferation, lipid metabolism and cholesterol metabolism. Nonetheless, the association between microRNA-33 and cellular senescence and its underlying molecular mechanism are far to be elucidated. The present study has attempted to probe into the effect of microRNA-33 on MEFs senescence. Our data unveiled that microRNA-33 was dramatically down-regulated in senescent MEFs compared to the young MEFs, and ectopic expression of microRNA-33 promoted MEFs senescence, while knock-down of microRNA-33 exhibited a protective effect against senescence phenotype. Moreover, we verified CDK6 as a direct target of microRNA-33 in mouse. Silencing of CDK6 induced the premature senescence phenotype of MEFs similarly as microRNA-33, while enforced expression of CDK6 significantly reverse the senescence-induction effect of microRNA-33. Taken together, our results suggested that microRNA-33 enhanced the replicative senescence of MEFs potentially by suppressing CDK6 expression. -- Highlights: •MicroRNA-33 was dramatically down-regulated in senescent MEF cells. •Altered expression of microRNA-33 exerted a critical role in MEFs senescence. •MicroRNA-33 promoted the replicative senescence of MEFs via targeting of CDK6.

  6. Association of Human Papillomavirus 16 E2 with Rad50-Interacting Protein 1 Enhances Viral DNA Replication.

    Science.gov (United States)

    Campos-León, Karen; Wijendra, Kalpanee; Siddiqa, Abida; Pentland, Ieisha; Feeney, Katherine M; Knapman, Alison; Davies, Rachel; Androphy, Elliot J; Parish, Joanna L

    2017-03-01

    Rad50-interacting protein 1 (Rint1) associates with the DNA damage response protein Rad50 during the transition from the S phase to the G 2 /M phase and functions in radiation-induced G 2 checkpoint control. It has also been demonstrated that Rint1 is essential in vesicle trafficking from the Golgi apparatus to the endoplasmic reticulum (ER) through an interaction with Zeste-White 10 (ZW10). We have isolated a novel interaction between Rint1 and the human papillomavirus 16 (HPV16) transcription and replication factor E2. E2 binds to Rint1 within its ZW10 interaction domain, and we show that in the absence of E2, Rint1 is localized to the ER and associates with ZW10. E2 expression results in a disruption of the Rint1-ZW10 interaction and an accumulation of nuclear Rint1, coincident with a significant reduction in vesicle movement from the ER to the Golgi apparatus. Interestingly, nuclear Rint1 and members of the Mre11/Rad50/Nbs1 (MRN) complex were found in distinct E2 nuclear foci, which peaked during mid-S phase, indicating that the recruitment of Rint1 to E2 foci within the nucleus may also result in the recruitment of this DNA damage-sensing protein complex. We show that exogenous Rint1 expression enhances E2-dependent virus replication. Conversely, the overexpression of a truncated Rint1 protein that retains the E2 binding domain but not the Rad50 binding domain acts as a dominant negative inhibitor of E2-dependent HPV replication. Put together, these experiments demonstrate that the interaction between Rint1 and E2 has an important function in HPV replication. IMPORTANCE HPV infections are an important driver of many epithelial cancers, including those within the anogenital and oropharyngeal tracts. The HPV life cycle is tightly regulated and intimately linked to the differentiation of the epithelial cells that it infects. HPV replication factories formed in the nucleus are locations where viral DNA is copied to support virus persistence and amplification of

  7. Adeno-associated viral vector-induced overexpression of neuropeptide Y Y2 receptors in the hippocampus suppresses seizures

    DEFF Research Database (Denmark)

    Woldbye, David Paul Drucker; Ängehagen, Mikael; Gøtzsche, Casper René

    2010-01-01

    Gene therapy using recombinant adeno-associated viral vectors overexpressing neuropeptide Y in the hippocampus exerts seizure-suppressant effects in rodent epilepsy models and is currently considered for clinical application in patients with intractable mesial temporal lobe epilepsy. Seizure...... recombinant adeno-associated viral vectors. In two temporal lobe epilepsy models, electrical kindling and kainate-induced seizures, vector-based transduction of Y2 receptor complementary DNA in the hippocampus of adult rats exerted seizure-suppressant effects. Simultaneous overexpression of Y2...

  8. A highly intensified ART regimen induces long-term viral suppression and restriction of the viral reservoir in a simian AIDS model.

    Directory of Open Access Journals (Sweden)

    Iart Luca Shytaj

    Full Text Available Stably suppressed viremia during ART is essential for establishing reliable simian models for HIV/AIDS. We tested the efficacy of a multidrug ART (highly intensified ART in a wide range of viremic conditions (10³-10⁷ viral RNA copies/mL in SIVmac251-infected rhesus macaques, and its impact on the viral reservoir. Eleven macaques in the pre-AIDS stage of the disease were treated with a multidrug combination (highly intensified ART consisting of two nucleosidic/nucleotidic reverse transcriptase inhibitors (emtricitabine and tenofovir, an integrase inhibitor (raltegravir, a protease inhibitor (ritonavir-boosted darunavir and the CCR5 blocker maraviroc. All animals stably displayed viral loads below the limit of detection of the assay (i.e. <40 RNA copies/mL after starting highly intensified ART. By increasing the sensitivity of the assay to 3 RNA copies/mL, viral load was still below the limit of detection in all subjects tested. Importantly, viral DNA resulted below the assay detection limit (<2 copies of DNA/5*10⁵ cells in PBMCs and rectal biopsies of all animals at the end of the follow-up, and in lymph node biopsies from the majority of the study subjects. Moreover, highly intensified ART decreased central/transitional memory, effector memory and activated (HLA-DR⁺ effector memory CD4⁺ T-cells in vivo, in line with the role of these subsets as the main cell subpopulations harbouring the virus. Finally, treatment with highly intensified ART at viral load rebound following suspension of a previous anti-reservoir therapy eventually improved the spontaneous containment of viral load following suspension of the second therapeutic cycle, thus leading to a persistent suppression of viremia in the absence of ART. In conclusion, we show, for the first time, complete suppression of viral load by highly intensified ART and a likely associated restriction of the viral reservoir in the macaque AIDS model, making it a useful platform for testing

  9. Reinitiated viral RNA-dependent RNA polymerase resumes replication at a reduced rate

    NARCIS (Netherlands)

    Vilfan, I.D.; Candelli, A.; Hage, S.; Aalto, A.P.; Poranen, M.M.; Bamford, D.H.; Dekker, N.H.

    2008-01-01

    RNA-dependent RNA polymerases (RdRP) form an important class of enzymes that is responsible for genome replication and transcription in RNA viruses and involved in the regulation of RNA interference in plants and fungi. The RdRP kinetics have been extensively studied, but pausing, an important

  10. Functional mapping of regions of the Autographa californica nuclear polyhedrosis viral genome required for DNA replication

    NARCIS (Netherlands)

    Kool, M.; Voeten, J. T.; Goldbach, R. W.; Vlak, J. M.

    1994-01-01

    Previous results showed that plasmids containing one of the eight putative origins (ori's) of Autographa californica nuclear polyhedrosis virus (AcMNPV) are replicated after transfection into Spodoptera frugiperda cells if essential trans-acting factors are supplied by AcMNPV infection (Kool et al.,

  11. Adeno-Associated Viral-Mediated Catalase Expression Suppresses Optic Neuritis in Experimental Allergic Encephalomyelitis

    Science.gov (United States)

    Guy, John; Qi, Xiaoping; Hauswirth, William W.

    1998-11-01

    Suppression of oxidative injury by viral-mediated transfer of the human catalase gene was tested in the optic nerves of animals with experimental allergic encephalomyelitis (EAE). EAE is an inflammatory autoimmune disorder of primary central nervous system demyelination that has been frequently used as an animal model for the human disease multiple sclerosis (MS). The optic nerve is a frequent site of involvement common to both EAE and MS. Recombinant adeno-associated virus containing the human gene for catalase was injected over the right optic nerve heads of SJL/J mice that were simultaneously sensitized for EAE. After 1 month, cell-specific catalase activity, evaluated by quantitation of catalase immunogold, was increased approximately 2-fold each in endothelia, oligodendroglia, astrocytes, and axons of the optic nerve. Effects of catalase on the histologic lesions of EAE were measured by computerized analysis of the myelin sheath area (for demyelination), optic disc area (for optic nerve head swelling), extent of the cellular infiltrate, extravasated serum albumin labeled by immunogold (for blood-brain barrier disruption), and in vivo H2O2 reaction product. Relative to control, contralateral optic nerves injected with the recombinant virus without a therapeutic gene, catalase gene inoculation reduced demyelination by 38%, optic nerve head swelling by 29%, cellular infiltration by 34%, disruption of the blood-brain barrier by 64%, and in vivo levels of H2O2 by 61%. Because the efficacy of potential treatments for MS are usually initially tested in the EAE animal model, this study suggests that catalase gene delivery by using viral vectors may be a therapeutic strategy for suppression of MS.

  12. Well begun is half done: Rubella virus perturbs autophagy signaling, thereby facilitating the construction of viral replication compartments.

    Science.gov (United States)

    Orosz, László; Megyeri, Klára

    2016-04-01

    The rubella virus is the causative agent of postnatal German measles and the congenital rubella syndrome. The majority of the rubella virus replication complexes originate from the endomembrane system. The rubella virus perturbs the signaling pathways regulating the formation of autophagic membranes in the infected cells, including the Ras/Raf/MEK/ERK and PI3K/Akt pathways. It is widely accepted that these pathways inhibit autophagy. In contrast, the class III PI3K enzymes are essential for autophagy initiation. By manipulating the Ras/Raf/MEK/ERK, class I PI3K/Akt and class III PI3K axes of signal transduction, the rubella virus may differentially regulate the autophagic cascade, with consequent stimulation of the initiation and strong suppression of the later phases. Dysregulation of autophagy by this virus can have a significant impact on the construction of replication compartments by regulating membrane trafficking. We hypothesize that the rubella virus perturbs the autophagic process in order to prevent the degradation of the virus progeny, and to ensure its replication by hijacking omegasomes for the construction of the replication complexes. The virus is therefore able to utilize an antiviral mechanism to its own advantage. Therapeutic modalities targeting the autophagic process may help to ameliorate the serious consequences of the congenital rubella syndrome. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Complete suppression of viral gene expression is associated with the onset and progression of lymphoid malignancy: observations in Bovine Leukemia Virus-infected sheep

    Directory of Open Access Journals (Sweden)

    Burny Arsène

    2007-07-01

    Full Text Available Abstract Background During malignant progression, tumor cells need to acquire novel characteristics that lead to uncontrolled growth and reduced immunogenicity. In the Bovine Leukemia Virus-induced ovine leukemia model, silencing of viral gene expression has been proposed as a mechanism leading to immune evasion. However, whether proviral expression in tumors is completely suppressed in vivo was not conclusively demonstrated. Therefore, we studied viral expression in two selected experimentally-infected sheep, the virus or the disease of which had features that made it possible to distinguish tumor cells from their nontransformed counterparts. Results In the first animal, we observed the emergence of a genetically modified provirus simultaneously with leukemia onset. We found a Tax-mutated (TaxK303 replication-deficient provirus in the malignant B-cell clone while functional provirus (TaxE303 had been consistently monitored over the 17-month aleukemic period. In the second case, both non-transformed and transformed BLV-infected cells were present at the same time, but at distinct sites. While there was potentially-active provirus in the non-leukemic blood B-cell population, as demonstrated by ex-vivo culture and injection into naïve sheep, virus expression was completely suppressed in the malignant B-cells isolated from the lymphoid tumors despite the absence of genetic alterations in the proviral genome. These observations suggest that silencing of viral genes, including the oncoprotein Tax, is associated with tumor onset. Conclusion Our findings suggest that silencing is critical for tumor progression and identify two distinct mechanisms-genetic and epigenetic-involved in the complete suppression of virus and Tax expression. We demonstrate that, in contrast to systems that require sustained oncogene expression, the major viral transforming protein Tax can be turned-off without reversing the transformed phenotype. We propose that suppression

  14. Roles of HIV-1 capsid in viral replication and immune evasion.

    Science.gov (United States)

    Le Sage, Valerie; Mouland, Andrew J; Valiente-Echeverría, Fernando

    2014-11-26

    The primary roles of the human immunodeficiency virus type 1 (HIV-1) capsid (CA) protein are to encapsidate and protect the viral RNA genome. It is becoming increasing apparent that HIV-1 CA is a multifunctional protein that acts early during infection to coordinate uncoating, reverse transcription, nuclear import of the pre-integration complex and integration of double stranded viral DNA into the host genome. Additionally, numerous recent studies indicate that CA is playing a crucial function in HIV-1 immune evasion. Here we summarize the current knowledge on HIV-1 CA and its interactions with the host cell to promote infection. The fact that CA engages in a number of different protein-protein interactions with the host makes it an interesting target for the development of new potent antiviral agents. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Mutational Analysis of the Hypervariable Region of Hepatitis E Virus Reveals Its Involvement in the Efficiency of Viral RNA Replication

    Science.gov (United States)

    Pudupakam, R. S.; Kenney, Scott P.; Córdoba, Laura; Huang, Yao-Wei; Dryman, Barbara A.; LeRoith, Tanya; Pierson, F. William; Meng, Xiang-Jin

    2011-01-01

    The RNA genome of the hepatitis E virus (HEV) contains a hypervariable region (HVR) in ORF1 that tolerates small deletions with respect to infectivity. To further investigate the role of the HVR in HEV replication, we constructed a panel of mutants with overlapping deletions in the N-terminal, central, and C-terminal regions of the HVR by using a genotype 1 human HEV luciferase replicon and analyzed the effects of deletions on viral RNA replication in Huh7 cells. We found that the replication levels of the HVR deletion mutants were markedly reduced in Huh7 cells, suggesting a role of the HVR in viral replication efficiency. To further verify the results, we constructed HVR deletion mutants by using a genetically divergent, nonmammalian avian HEV, and similar effects on viral replication efficiency were observed when the avian HEV mutants were tested in LMH cells. Furthermore, the impact of complete HVR deletion on virus infectivity was tested in chickens, using an avian HEV mutant with a complete HVR deletion. Although the deletion mutant was still replication competent in LMH cells, the complete HVR deletion resulted in a loss of avian HEV infectivity in chickens. Since the HVR exhibits extensive variations in sequence and length among different HEV genotypes, we further examined the interchangeability of HVRs and demonstrated that HVR sequences are functionally exchangeable between HEV genotypes with regard to viral replication and infectivity in vitro, although genotype-specific HVR differences in replication efficiency were observed. The results showed that although the HVR tolerates small deletions with regard to infectivity, it may interact with viral and host factors to modulate the efficiency of HEV replication. PMID:21775444

  16. Stem cell gene therapy for HIV: strategies to inhibit viral entry and replication.

    Science.gov (United States)

    DiGiusto, David L

    2015-03-01

    Since the demonstration of a cure of an HIV+ patient with an allogeneic stem cell transplant using naturally HIV-resistant cells, significant interest in creating similar autologous products has fueled the development of a variety of "cell engineering" approaches to stem cell therapy for HIV. Among the more well-studied strategies is the inhibition of viral entry through disruption of expression of viral co-receptors or through competitive inhibitors of viral fusion with the cell membrane. Preclinical evaluation of these approaches often starts in vitro but ultimately is tested in animal models prior to clinical implementation. In this review, we trace the development of several key approaches (meganucleases, short hairpin RNA (shRNA), and fusion inhibitors) to modification of hematopoietic stem cells designed to impart resistance to HIV to their T-cell and monocytic progeny. The basic evolution of technologies through in vitro and in vivo testing is discussed as well as the pros and cons of each approach and how the addition of postentry inhibitors may enhance the overall antiviral efficacy of these approaches.

  17. Autophagy and Mammalian Viruses: Roles in Immune Response, Viral Replication, and Beyond.

    Science.gov (United States)

    Paul, P; Münz, C

    2016-01-01

    Autophagy is an important cellular catabolic process conserved from yeast to man. Double-membrane vesicles deliver their cargo to the lysosome for degradation. Hence, autophagy is one of the key mechanisms mammalian cells deploy to rid themselves of intracellular pathogens including viruses. However, autophagy serves many more functions during viral infection. First, it regulates the immune response through selective degradation of immune components, thus preventing possibly harmful overactivation and inflammation. Additionally, it delivers virus-derived antigens to antigen-loading compartments for presentation to T lymphocytes. Second, it might take an active part in the viral life cycle by, eg, facilitating its release from cells. Lastly, in the constant arms race between host and virus, autophagy is often hijacked by viruses and manipulated to their own advantage. In this review, we will highlight key steps during viral infection in which autophagy plays a role. We have selected some exemplary viruses and will describe the molecular mechanisms behind their intricate relationship with the autophagic machinery, a result of host-pathogen coevolution. © 2016 Elsevier Inc. All rights reserved.

  18. CD41 T cell recovery during suppression of HIV replication: an international comparison of the immunological efficacy of antiretroviral therapy in North America, Asia and Africa.

    Science.gov (United States)

    Geng, Elvin H; Neilands, Torsten B; Thièbaut, Rodolphe; Bwana, Mwebesa Bosco; Nash, Denis; Moore, Richard D; Wood, Robin; Zannou, Djimon Marcel; Althoff, Keri N; Lim, Poh Lian; Nachega, Jean B; Easterbrook, Philippa J; Kambugu, Andrew; Little, Francesca; Nakigozi, Gertrude; Nakanjako, Damalie; Kiggundu, Valerian; Ki Li, Patrick Chung; Bangsberg, David R; Fox, Matthew P; Prozesky, HansW; Hunt, Peter W; Davies, Mary-Ann; Reynolds, Steven J; Egger, Matthias; Yiannoutsos, Constantin T; Vittinghoff, Eric V; Deeks, Steven G; Martin, Jeffrey N

    2015-02-01

    Even among HIV-infected patients who fully suppress plasma HIV RNA replication on antiretroviral therapy, genetic (e.g. CCL3L1 copy number), viral (e.g. tropism) and environmental (e.g. chronic exposure to microbial antigens) factors influence CD4 recovery. These factors differ markedly around the world and therefore the expected CD4 recovery during HIV RNA suppression may differ globally. We evaluated HIV-infected adults from North America, West Africa, East Africa, Southern Africa and Asia starting non-nucleoside reverse transcriptase inhibitorbased regimens containing efavirenz or nevirapine, who achieved at least one HIV RNA level Africa showed diminished CD4 recovery as compared with other regions. Three years after antiretroviral therapy initiation, the mean CD4 count for a prototypical patient with a pre-therapy CD4 count of 150/ml was 529/ml [95% confidence interval (CI): 517–541] in North America, 494/ml (95% CI: 429–559) in West Africa, 515/ml (95% CI: 508–522) in Southern Africa, 503/ml (95% CI: 478–528) in Asia and 437/ml (95% CI: 425–449) in East Africa. CD4 recovery during HIV RNA suppression is diminished in East Africa as compared with other regions of the world, and observed differences are large enough to potentially influence clinical outcomes. Epidemiological analyses on a global scale can identify macroscopic effects unobservable at the clinical, national or individual regional level.

  19. Suppression of matrix protein synthesis in endothelial cells by herpes simplex virus is not dependent on viral protein synthesis

    International Nuclear Information System (INIS)

    Kefalides, N.A.

    1986-01-01

    The synthesis of matrix proteins by human endothelial cells (EC) in vitro was studied before and at various times after infection with Herpes Simplex virus Type 1 (HSV-1) or 2 (HSV-2). Monolayers of EC were either mock-infected or infected with virus for 1 hr at a multiplicity infection (MOI) of 5 to 20 at 37 0 C. Control and infected cultures were pulse-labeled for 1 or 2 hrs with either [ 14 C]proline or [ 35 S]methionine. Synthesis of labeled matrix proteins was determined by SDS-gel electrophoresis. Suppression of synthesis of fibronectin, Type IV collagen and thrombospondin began as early as 2 hrs and became almost complete by 10 hrs post-infection. The degree of suppression varied with the protein and the virus dose. Suppression of Type IV collagen occurred first followed by that of fibronectin and then thrombospondin. Infection of EC with UV irradiated HSV-1 or HSV-2 resulted in suppression of host-cell protein synthesis as well as viral protein synthesis. Infection with intact virus in the presence of actinomycin-D resulted in suppression of both host-cell and viral protein synthesis. The data indicate that infection of EC with HSV leads to suppression of matrix protein synthesis which does not depend on viral protein synthesis

  20. Functional Connectivity in Virally Suppressed Patients with HIV-Associated Neurocognitive Disorder: A Resting-State Analysis.

    Science.gov (United States)

    Chaganti, J R; Heinecke, A; Gates, T M; Moffat, K J; Brew, B J

    2017-08-01

    HIV-associated neurocognitive disorder still occurs despite virally suppressive combination antiretroviral therapy. In the pre-combination antiretroviral era and in patients without HIV suppression, HIV-associated neurocognitive disorder was caused by synaptodendritic injury resulting in impairment of neural networks, characterized by decreased attention, psychomotor slowing, and working memory deficits. Whether similar pathogenesis is true for HIV-associated neurocognitive disorder in the context of viral suppression is not clear. Resting-state fMRI has been shown to be efficient in detecting impaired neural networks in various neurologic illnesses. This pilot study aimed to assess resting-state functional connectivity of the brain in patients with active HIV-associated neurocognitive disorder in the context of HIV viral suppression in both blood and CSF. Eighteen patients with active HIV-associated neurocognitive disorder (recent diagnosis with progressing symptoms) on combination antiretroviral therapy with viral suppression in both blood and CSF and 9 demographically matched control subjects underwent resting-state functional MR imaging. The connectivity in the 6 known neural networks was assessed. To localize significant ROIs within the HIV and control group, we performed a seed-based correlation for each known resting-state network. There were significant group differences between the control and HIV-associated neurocognitive disorder groups in the salience (0.26 versus 0.14, t = 2.6978, df = 25, P = .0123) and executive networks (0.52 versus 0.32, t = 2.2372, df = 25, P = .034). The covariate analysis with neuropsychological scores yielded statistically significant correlations in all 6 studied functional networks, with the most conspicuous correlation in salience networks. Active HIV-associated neurocognitive disorder in virally suppressed patients is associated with significantly decreased connectivity in the salience and executive networks, thereby making

  1. Retinoid X Receptor α-Dependent HBV Minichromosome Remodeling and Viral Replication.

    Science.gov (United States)

    Zhang, Yan; He, Song; Guo, Jin-Jun; Peng, Hong; Fan, Jia-Hao; Li, Qing-Ling

    2017-01-01

    The HBV covalently closed circular DNA (cccDNA) is organized into a minichromosome in the nuclei of infected hepatocytes through interactions with histone and nonhistone proteins. Retinoid X receptor α (RXRα), a liver-enriched nuclear receptor, participates in regulation of HBV replication and transcription through modulation of HBV enhancer 1 and core promoter activity. This study investigated RXRα involvement in HBV cccDNA epigenetic modifications. Quantitative cccDNA chromatin immunoprecipitation (ChIP) was applied to study the recruitment of RXRα, histones, and chromatin-modifying enzymes to HBV minichromosome in HepG2 cells after transfection of the linear HBV genome. RXRα Was found to directly bind to HBV cccDNA; recruitment of RXRα to HBV mini-chromosome paralleled HBV replication, histone recruitment, and histone acetylation in HBVcccDNA. Moreover, RXRα overexpression or knock-down significantly increased or impaired the recruitment of the p300 acetyltransferase to cccDNAminichromosome. Our results confirmed the regulation of RXRα on HBV replication in vitro and demonstrated the modulation of RXRα on HBV cccDNA epigenetics. These findings provide a profound theoretical and experimental basis for late-model antiviral treatment acting on the HBV cccDNA and minichromosome.

  2. Prior Virus Exposure Alters the Long-Term Landscape of Viral Replication during Feline Lentiviral Infection

    Directory of Open Access Journals (Sweden)

    Sue VandeWoude

    2011-10-01

    Full Text Available We developed a feline model of lentiviral cross-species transmission using a puma lentivirus (PLV or FIVPco which infects domestic cats but does not cause disease. Infection with PLV protects cats from CD4+ T-cell decline caused by subsequent infection with virulent feline immunodeficiency virus (FIV. Previous studies implicate innate immune and/or cellular restriction mechanisms for FIV disease attenuation in PLV-infected cats. In this study, we evaluated viral infection and cytokine mRNA transcription in 12 different tissue reservoirs approximately five months post infection. We quantitated tissue proviral load, viral mRNA load and relative transcription of IL-10, IL-12p40 and IFNγ from tissues of cats exposed to FIV, PLV or both viruses and analyzed these parameters using a multivariate statistical approach. The distribution and intensity of FIV infection and IFNγ transcription differed between single and co-infected cats, characterized by higher FIV proviral loads and IFNγ expression in co-infected cat tissues. Variability in FIV mRNA load and IFNγ was significantly more constrained in co-infected versus singly infected cat tissues. Single-infected:co-infected ratios of FIV mRNA load compared to FIV proviral load indicated that active viral transcription was apparently inhibited during co-infection. These results indicate that previous PLV infection increases activation of tissue innate immunity and constrains the ability of FIV to productively infect tissue reservoirs of infection for months, independent of FIV proviral load, supporting a model in which innate immunity and/or modulation of target cell susceptibility play a key role in PLV-induced protection from FIV disease.

  3. HIV care visits and time to viral suppression, 19 U.S. jurisdictions, and implications for treatment, prevention and the national HIV/AIDS strategy.

    Directory of Open Access Journals (Sweden)

    H Irene Hall

    Full Text Available OBJECTIVE: Early and regular care and treatment for human immunodeficiency virus (HIV infection are associated with viral suppression, reductions in transmission risk and improved health outcomes for persons with HIV. We determined, on a population level, the association of care visits with time from HIV diagnosis to viral suppression. METHODS: Using data from 19 areas reporting HIV-related tests to national HIV surveillance, we determined time from diagnosis to viral suppression among 17,028 persons diagnosed with HIV during 2009, followed through December 2011, using data reported through December 2012. Using Cox proportional hazards models, we assessed factors associated with viral suppression, including linkage to care within 3 months of diagnosis, a goal set forth by the National HIV/AIDS Strategy, and number of HIV care visits as determined by CD4 and viral load test results, while controlling for demographic, clinical, and risk characteristics. RESULTS: Of 17,028 persons diagnosed with HIV during 2009 in the 19 areas, 76.6% were linked to care within 3 months of diagnosis and 57.0% had a suppressed viral load during the observation period. Median time from diagnosis to viral suppression was 19 months overall, and 8 months among persons with an initial CD4 count ≤ 350 cells/µL. During the first 12 months after diagnosis, persons linked to care within 3 months experienced shorter times to viral suppression (higher rate of viral suppression per unit time, hazard ratio [HR] = 4.84 versus not linked within 3 months; 95% confidence interval [CI] 4.27, 5.48. Persons with a higher number of time-updated care visits also experienced a shorter time to viral suppression (HR = 1.51 per additional visit, 95% CI 1.49, 1.52. CONCLUSIONS: Timely linkage to care and greater frequency of care visits were associated with faster time to viral suppression with implications for individual health outcomes and for secondary prevention.

  4. VP-16 and alkylating agents activate a common metabolic pathway for suppression of DNA replication

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.K.; Berger, N.A.

    1986-05-01

    The cytotoxic effects of etoposide (VP-16) are mediated by topoisomerase II production of protein crosslinked DNA strand breaks. Previous studies have shown that alkylating agent induced DNA damage results in expansion of dTTP pools and reduction of dCTP pools and DNA replication. Studies were conducted with V79 cells to determine whether the metabolic consequences of VP-16 treatment were similar to those induced by alkylating agents. Treatment with 0.5..mu..M VP-16 prolonged the doubling time of V79 cells from 12 to 18 hrs and caused cell volume to increase from 1.1 to 1.6 x 10/sup -12/l. 2mM caffeine completely blocked the volume increase and substantially prevented the prolongation of doubling time. 5..mu..M VP-16 reduced the rate of (/sup 3/H)TdR incorporation by 70%, whereas in the presence of 2mM caffeine, VP-16 caused only a 10% decrease in the rate of (/sup 3/H)TdR incorporation. 4 hr treatment with 5.0..mu..M VP-16 increased dTTP levels from 65 +/- 10 pmol/10/sup 6/ cells to 80 +/- 13 pmol/10/sup 6/ cells and caused dCTP level to decline from 113 +/- 23 pmol/10/sup 6/ cells to 92 +/- 17 pmol/10/sup 6/ cells. These results indicate that the metabolic consequences of VP-16 treatment are similar to alkylating agent treatment and that an increase in dTTP pools with a subsequent effect on ribonucleotide reductase may be a final common pathway by which many cytotoxic agents suppress DNA synthesis.

  5. VP-16 and alkylating agents activate a common metabolic pathway for suppression of DNA replication

    International Nuclear Information System (INIS)

    Das, S.K.; Berger, N.A.

    1986-01-01

    The cytotoxic effects of etoposide (VP-16) are mediated by topoisomerase II production of protein crosslinked DNA strand breaks. Previous studies have shown that alkylating agent induced DNA damage results in expansion of dTTP pools and reduction of dCTP pools and DNA replication. Studies were conducted with V79 cells to determine whether the metabolic consequences of VP-16 treatment were similar to those induced by alkylating agents. Treatment with 0.5μM VP-16 prolonged the doubling time of V79 cells from 12 to 18 hrs and caused cell volume to increase from 1.1 to 1.6 x 10 -12 l. 2mM caffeine completely blocked the volume increase and substantially prevented the prolongation of doubling time. 5μM VP-16 reduced the rate of [ 3 H]TdR incorporation by 70%, whereas in the presence of 2mM caffeine, VP-16 caused only a 10% decrease in the rate of [ 3 H]TdR incorporation. 4 hr treatment with 5.0μM VP-16 increased dTTP levels from 65 +/- 10 pmol/10 6 cells to 80 +/- 13 pmol/10 6 cells and caused dCTP level to decline from 113 +/- 23 pmol/10 6 cells to 92 +/- 17 pmol/10 6 cells. These results indicate that the metabolic consequences of VP-16 treatment are similar to alkylating agent treatment and that an increase in dTTP pools with a subsequent effect on ribonucleotide reductase may be a final common pathway by which many cytotoxic agents suppress DNA synthesis

  6. Experimentally-induced immune activation in natural hosts of SIV induces significant increases in viral replication and CD4+ T cell depletion

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Ruy M [Los Alamos National Laboratory

    2008-01-01

    Chronically SIVagm-infected African green monkeys (AGMs) have a remarkably stable non-pathogenic disease course, with levels of immune activation in chronic SIVagm infection similar to those observed in uninfected monkeys and stable viral loads (VLs) for long periods of time. In vivo administration of lipopolysaccharide (LPS) or an IL-2/diphtheria toxin fusion protein (Ontak) to chronically SIVagm-infected AGMs triggered increases in immune activation and subsequently of viral replication and depletion of intestinal CD4{sup +} T cells. Our study indicates that circulating microbial products can increase viral replication by inducing immune activation and increasing the number of viral target cells, thus demonstrating that immune activation and T cell prolifeation are key factors in AIDS pathogenesis.

  7. Immune responses elicited against rotavirus middle layer protein VP6 inhibit viral replication in vitro and in vivo

    Science.gov (United States)

    Lappalainen, Suvi; Pastor, Ana Ruth; Tamminen, Kirsi; López-Guerrero, Vanessa; Esquivel-Guadarrama, Fernando; Palomares, Laura A; Vesikari, Timo; Blazevic, Vesna

    2014-01-01

    Rotavirus (RV) is a common cause of severe gastroenteritis (GE) in children worldwide. Live oral RV vaccines protect against severe RVGE, but the immune correlates of protection are not yet clearly defined. Inner capsid VP6 protein is a highly conserved, abundant, and immunogenic RV protein, and VP6-specific mucosal antibodies, especially IgA, have been implicated to protect against viral challenge in mice. In the present study systemic and mucosal IgG and IgA responses were induced by immunizing BALB/c mice intranasally with a combination of recombinant RV VP6 protein (subgroup II [SGII]) and norovirus (NoV) virus-like particles (VLPs) used in a candidate vaccine. Following immunization mice were challenged orally with murine RV strain EDIMwt (SG non-I-non-II, G3P10[16]). In order to determine neutralizing activity of fecal samples, sera, and vaginal washes (VW) against human Wa RV (SGII, G1P1A[8]) and rhesus RV (SGI, G3P5B[3]), the RV antigen production was measured with an ELISA-based antigen reduction neutralization assay. Only VWs of immunized mice inhibited replication of both RVs, indicating heterotypic protection of induced antibodies. IgA antibody depletion and blocking experiments using recombinant VP6 confirmed that neutralization was mediated by anti-VP6 IgA antibodies. Most importantly, after the RV challenge significant reduction in viral shedding was observed in feces of immunized mice. These results suggest a significant role for mucosal RV VP6-specific IgA for the inhibition of RV replication in vitro and in vivo. In addition, these results underline the importance of non-serotype-specific immunity induced by the conserved subgroup-specific RV antigen VP6 in clearance of RV infection. PMID:25424814

  8. Degradation of cellular mir-27 by a novel, highly abundant viral transcript is important for efficient virus replication in vivo.

    Directory of Open Access Journals (Sweden)

    Lisa Marcinowski

    2012-02-01

    Full Text Available Cytomegaloviruses express large amounts of viral miRNAs during lytic infection, yet, they only modestly alter the cellular miRNA profile. The most prominent alteration upon lytic murine cytomegalovirus (MCMV infection is the rapid degradation of the cellular miR-27a and miR-27b. Here, we report that this regulation is mediated by the ∼1.7 kb spliced and highly abundant MCMV m169 transcript. Specificity to miR-27a/b is mediated by a single, apparently optimized, miRNA binding site located in its 3'-UTR. This site is easily and efficiently retargeted to other cellular and viral miRNAs by target site replacement. Expression of the 3'-UTR of m169 by an adenoviral vector was sufficient to mediate its function, indicating that no other viral factors are essential in this process. Degradation of miR-27a/b was found to be accompanied by 3'-tailing and -trimming. Despite its dramatic effect on miRNA stability, we found this interaction to be mutual, indicating potential regulation of m169 by miR-27a/b. Most interestingly, three mutant viruses no longer able to target miR-27a/b, either due to miRNA target site disruption or target site replacement, showed significant attenuation in multiple organs as early as 4 days post infection, indicating that degradation of miR-27a/b is important for efficient MCMV replication in vivo.

  9. Cell-Free and Cell-Based Approaches to Explore the Roles of Host Membranes and Lipids in the Formation of Viral Replication Compartment Induced by Tombusviruses.

    Science.gov (United States)

    Nagy, Peter D; Pogany, Judit; Xu, Kai

    2016-03-03

    Plant positive strand RNA viruses are intracellular infectious agents that take advantage of cellular lipids and membranes to support replication and protect viral RNA from degradation by host antiviral responses. In this review, we discuss how Tomato bushy stunt virus (TBSV) co-opts lipid transfer proteins and modulates lipid metabolism and transport to facilitate the assembly of the membrane-bound viral replicase complexes within intricate replication compartments. Identification and characterization of the proviral roles of specific lipids and proteins involved in lipid metabolism based on results from yeast (Saccharomyces cerevisiae) model host and cell-free approaches are discussed. The review also highlights the advantage of using liposomes with chemically defined composition to identify specific lipids required for TBSV replication. Remarkably, all the known steps in TBSV replication are dependent on cellular lipids and co-opted membranes.

  10. Hsp90 interacts specifically with viral RNA and differentially regulates replication initiation of Bamboo mosaic virus and associated satellite RNA.

    Directory of Open Access Journals (Sweden)

    Ying Wen Huang

    Full Text Available Host factors play crucial roles in the replication of plus-strand RNA viruses. In this report, a heat shock protein 90 homologue of Nicotiana benthamiana, NbHsp90, was identified in association with partially purified replicase complexes from BaMV-infected tissue, and shown to specifically interact with the 3' untranslated region (3' UTR of BaMV genomic RNA, but not with the 3' UTR of BaMV-associated satellite RNA (satBaMV RNA or that of genomic RNA of other viruses, such as Potato virus X (PVX or Cucumber mosaic virus (CMV. Mutational analyses revealed that the interaction occurs between the middle domain of NbHsp90 and domain E of the BaMV 3' UTR. The knockdown or inhibition of NbHsp90 suppressed BaMV infectivity, but not that of satBaMV RNA, PVX, or CMV in N. benthamiana. Time-course analysis further revealed that the inhibitory effect of 17-AAG is significant only during the immediate early stages of BaMV replication. Moreover, yeast two-hybrid and GST pull-down assays demonstrated the existence of an interaction between NbHsp90 and the BaMV RNA-dependent RNA polymerase. These results reveal a novel role for NbHsp90 in the selective enhancement of BaMV replication, most likely through direct interaction with the 3' UTR of BaMV RNA during the initiation of BaMV RNA replication.

  11. Reactivation of viral replication in anti-HBe positive chronic HBsAg carriers

    DEFF Research Database (Denmark)

    Krogsgaard, K; Aldershvile, J; Kryger, Peter

    1990-01-01

    Reactivation of hepatitis B virus replication was investigated in an unselected group of 44 HBV DNA negative, anti-HBe positive chronic HBsAg carriers. Twenty-five patients (54%) were intravenous drug addicts and 7 (16%) were male homosexuals. Sixteen patients had evidence of delta infection...... and five of the seven male homosexuals had human immunodeficiency virus infection. The patients were followed for 1 to 180 months (median, 24 months) while HBV DNA negative, anti-HBe positive. Reactivation, defined as reappearance of HBV DNA or HBeAg, or both, was detected in six patients corresponding...... to an annual reactivation rate of 5%. Reactivation in four patients was detected by reversion to HBV DNA positivity only, whereas HBeAg/anti-HBe status remained unchanged. Two patients became both HBV DNA and HBeAg positive. None of the patients developed hepatitis-like symptoms and transaminase elevation...

  12. Kaposi's Sarcoma-Associated Herpesvirus K8 Is an RNA Binding Protein That Regulates Viral DNA Replication in Coordination with a Noncoding RNA.

    Science.gov (United States)

    Liu, Dongcheng; Wang, Yan; Yuan, Yan

    2018-01-10

    KSHV lytic replication and constant primary infection of fresh cells are crucial for viral tumorigenicity. Virus-encoded b-Zip family protein K8 plays an important role in viral DNA replication in both viral reactivation and de novo infection. The mechanism underlying the functional role of K8 in the viral life cycle is elusive. Here we report that K8 is a RNA binding protein, which also associates with many proteins including other RNA binding proteins. Many K8-involved protein-protein interactions are mediated by RNA. Using a c ross l inking and i mmuno p recipitation (CLIP) procedure combined with high-throughput sequencing, RNAs that are associated with K8 in BCBL-1 cells were identified, that include both viral (PAN, T1.4, T0.7 and etc.) and cellular (MALAT-1, MRP, 7SK and etc.) RNAs. An RNA-binding motif in K8 was defined, and mutation of the motif abolished the ability of K8 binding to many noncoding RNAs as well as viral DNA replication during de novo infection, suggesting that the K8 functions in viral replication are carried out through RNA association. The function of K8 and associated T1.4 RNA was investigated in details and results showed that T1.4 mediates the binding of K8 with ori-Lyt DNA. T1.4-K8 complex physically bound to KSHV ori-Lyt DNA and recruited other proteins and cofactors to assemble replication complex. Depletion of T1.4 abolished the DNA replication in primary infection. These findings provide mechanistic insights into the role of K8 in coordination with T1.4 RNA in regulating KSHV DNA replication during de novo infection. Importance Genome wide analyses of the mammalian transcriptome revealed that a large proportion of sequence previously annotated as noncoding region are actually transcribed and give rise to stable RNAs. Emergence of a large number of noncoding RNAs suggests that functional RNA-protein complexes exampled by ribosome or spliceosome are not ancient relics of the last riboorganism but would be well adapted for

  13. CD200R1 supports HSV-1 viral replication and licenses pro-inflammatory signaling functions of TLR2.

    Directory of Open Access Journals (Sweden)

    Roy J Soberman

    Full Text Available The CD200R1:CD200 axis is traditionally considered to limit tissue inflammation by down-regulating pro-inflammatory signaling in myeloid cells bearing the receptor. We generated CD200R1(-/- mice and employed them to explore both the role of CD200R1 in regulating macrophage signaling via TLR2 as well as the host response to an in vivo, TLR2-dependent model, herpes simplex virus 1 (HSV-1 infection. CD200R1(-/- peritoneal macrophages demonstrated a 70-75% decrease in the generation of IL-6 and CCL5 (Rantes in response to the TLR2 agonist Pam(2CSK(4 and to HSV-1. CD200R1(-/- macrophages could neither up-regulate the expression of TLR2, nor assemble a functional inflammasome in response to HSV-1. CD200R1(-/- mice were protected from HSV-1 infection and exhibited dysfunctional TLR2 signaling. Finally, both CD200R1(-/- mice and CD200R1(-/- fibroblasts and macrophages showed a markedly reduced ability to support HSV-1 replication. In summary, our data demonstrate an unanticipated and novel requirement for CD200R1 in "licensing" pro-inflammatory functions of TLR2 and in limiting viral replication that are supported by ex vivo and in vivo evidence.

  14. Zinc binding activity of human metapneumovirus M2-1 protein is indispensable for viral replication and pathogenesis in vivo.

    Science.gov (United States)

    Cai, Hui; Zhang, Yu; Ma, Yuanmei; Sun, Jing; Liang, Xueya; Li, Jianrong

    2015-06-01

    Human metapneumovirus (hMPV) is a member of the Pneumovirinae subfamily in the Paramyxoviridae family that causes respiratory tract infections in humans. Unlike members of the Paramyxovirinae subfamily, the polymerase complex of pneumoviruses requires an additional cofactor, the M2-1 protein, which functions as a transcriptional antitermination factor. The M2-1 protein was found to incorporate zinc ions, although the specific role(s) of the zinc binding activity in viral replication and pathogenesis remains unknown. In this study, we found that the third cysteine (C21) and the last histidine (H25) in the zinc binding motif (CCCH) of hMPV M2-1 were essential for zinc binding activity, whereas the first two cysteines (C7 and C15) play only minor or redundant roles in zinc binding. In addition, the zinc binding motif is essential for the oligomerization of M2-1. Subsequently, recombinant hMPVs (rhMPVs) carrying mutations in the zinc binding motif were recovered. Interestingly, rhMPV-C21S and -H25L mutants, which lacked zinc binding activity, had delayed replication in cell culture and were highly attenuated in cotton rats. In contrast, rhMPV-C7S and -C15S strains, which retained 60% of the zinc binding activity, replicated as efficiently as rhMPV in cotton rats. Importantly, rhMPVs that lacked zinc binding activity triggered high levels of neutralizing antibody and provided complete protection against challenge with rhMPV. Taken together, these results demonstrate that zinc binding activity is indispensable for viral replication and pathogenesis in vivo. These results also suggest that inhibition of zinc binding activity may serve as a novel approach to rationally attenuate hMPV and perhaps other pneumoviruses for vaccine purposes. The pneumoviruses include many important human and animal pathogens, such as human respiratory syncytial virus (hRSV), hMPV, bovine RSV, and avian metapneumovirus (aMPV). Among these viruses, hRSV and hMPV are the leading causes of acute

  15. Enhanced Viral Replication and Modulated Innate Immune Responses in Infant Airway Epithelium following H1N1 Infection

    Science.gov (United States)

    Clay, Candice C.; Reader, J. Rachel; Gerriets, Joan E.; Wang, Theodore T.; Harrod, Kevin S.

    2014-01-01

    ABSTRACT Influenza is the cause of significant morbidity and mortality in pediatric populations. The contribution of pulmonary host defense mechanisms to viral respiratory infection susceptibility in very young children is poorly understood. As a surrogate to compare mucosal immune responses of infant and adult lungs, rhesus monkey primary airway epithelial cell cultures were infected with pandemic influenza A/H1N1 virus in vitro. Virus replication, cytokine secretion, cell viability, and type I interferon (IFN) pathway PCR array profiles were evaluated for both infant and adult cultures. In comparison with adult cultures, infant cultures showed significantly increased levels of H1N1 replication, reduced alpha interferon (IFN-α) protein synthesis, and no difference in cell death following infection. Age-dependent differences in expression levels of multiple genes associated with the type I IFN pathway were observed in H1N1-infected cultures. To investigate the pulmonary and systemic responses to H1N1 infection in early life, infant monkeys were inoculated with H1N1 by upper airway administration. Animals were monitored for virus and parameters of inflammation over a 14-day period. High H1N1 titers were recovered from airways at day 1, with viral RNA remaining detectable until day 9 postinfection. Despite viral clearance, bronchiolitis and alveolitis persisted at day 14 postinfection; histopathological analysis revealed alveolar septal thickening and intermittent type II pneumocyte hyperplasia. Our overall findings are consistent with the known susceptibility of pediatric populations to respiratory virus infection and suggest that intrinsic developmental differences in airway epithelial cell immune function may contribute to the limited efficacy of host defense during early childhood. IMPORTANCE To the best of our knowledge, this study represents the first report of intrinsic developmental differences in infant airway epithelial cells that may contribute to the

  16. Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells.

    Science.gov (United States)

    Foxman, Ellen F; Storer, James A; Fitzgerald, Megan E; Wasik, Bethany R; Hou, Lin; Zhao, Hongyu; Turner, Paul E; Pyle, Anna Marie; Iwasaki, Akiko

    2015-01-20

    Most isolates of human rhinovirus, the common cold virus, replicate more robustly at the cool temperatures found in the nasal cavity (33-35 °C) than at core body temperature (37 °C). To gain insight into the mechanism of temperature-dependent growth, we compared the transcriptional response of primary mouse airway epithelial cells infected with rhinovirus at 33 °C vs. 37 °C. Mouse airway cells infected with mouse-adapted rhinovirus 1B exhibited a striking enrichment in expression of antiviral defense response genes at 37 °C relative to 33 °C, which correlated with significantly higher expression levels of type I and type III IFN genes and IFN-stimulated genes (ISGs) at 37 °C. Temperature-dependent IFN induction in response to rhinovirus was dependent on the MAVS protein, a key signaling adaptor of the RIG-I-like receptors (RLRs). Stimulation of primary airway cells with the synthetic RLR ligand poly I:C led to greater IFN induction at 37 °C relative to 33 °C at early time points poststimulation and to a sustained increase in the induction of ISGs at 37 °C relative to 33 °C. Recombinant type I IFN also stimulated more robust induction of ISGs at 37 °C than at 33 °C. Genetic deficiency of MAVS or the type I IFN receptor in infected airway cells permitted higher levels of viral replication, particularly at 37 °C, and partially rescued the temperature-dependent growth phenotype. These findings demonstrate that in mouse airway cells, rhinovirus replicates preferentially at nasal cavity temperature due, in part, to a less efficient antiviral defense response of infected cells at cool temperature.

  17. Immune Responses and Viral Replication in Long-Term Inapparent Carrier Ponies Inoculated with Equine Infectious Anemia Virus

    Science.gov (United States)

    Hammond, Scott A.; Li, Feng; McKeon, Brian M.; Cook, Sheila J.; Issel, Charles J.; Montelaro, Ronald C.

    2000-01-01

    Persistent infection of equids by equine infectious anemia virus (EIAV) is typically characterized by a progression during the first year postinfection from chronic disease with recurring disease cycles to a long-term asymptomatic infection that is maintained indefinitely. The goal of the current study was to perform a comprehensive longitudinal analysis of the course of virus infection and development of host immunity in experimentally infected horses as they progressed from chronic disease to long-term inapparent carriage. We previously described the evolution of EIAV genomic quasispecies (C. Leroux, C. J. Issel, and R. C. Montelaro, J. Virol. 71:9627–9639, 1997) and host immune responses (S. A. Hammond, S. J. Cook, D. L. Lichtenstein, C. J. Issel, and R. C. Montelaro, J. Virol. 71:3840–3852, 1997) in four experimentally infected ponies during sequential disease episodes associated with chronic disease during the first 10 months postinfection. In the current study, we extended the studies of these experimentally infected ponies to 3 years postinfection to characterize the levels of virus replication and development of host immune responses associated with the progression from chronic disease to long-term inapparent infection. The results of these studies revealed over a 103-fold difference in the steady-state levels of plasma viral RNA detected during long-term inapparent infection that correlated with the severity of chronic disease, indicating different levels of control of virus replication during long-term inapparent infections. Detailed analyses of antibody and cellular immune responses in all four ponies over the 3-year course of infection revealed a similar evolution during the first year postinfection of robust humoral and cellular immunity that then remained relatively constant during long-term inapparent infection. These observations indicate that immune parameters that have previously been correlated with EIAV vaccine protection fail to provide

  18. Immune responses and viral replication in long-term inapparent carrier ponies inoculated with equine infectious anemia virus.

    Science.gov (United States)

    Hammond, S A; Li, F; McKeon, B M; Cook, S J; Issel, C J; Montelaro, R C

    2000-07-01

    Persistent infection of equids by equine infectious anemia virus (EIAV) is typically characterized by a progression during the first year postinfection from chronic disease with recurring disease cycles to a long-term asymptomatic infection that is maintained indefinitely. The goal of the current study was to perform a comprehensive longitudinal analysis of the course of virus infection and development of host immunity in experimentally infected horses as they progressed from chronic disease to long-term inapparent carriage. We previously described the evolution of EIAV genomic quasispecies (C. Leroux, C. J. Issel, and R. C. Montelaro, J. Virol. 71:9627-9639, 1997) and host immune responses (S. A. Hammond, S. J. Cook, D. L. Lichtenstein, C. J. Issel, and R. C. Montelaro, J. Virol. 71:3840-3852, 1997) in four experimentally infected ponies during sequential disease episodes associated with chronic disease during the first 10 months postinfection. In the current study, we extended the studies of these experimentally infected ponies to 3 years postinfection to characterize the levels of virus replication and development of host immune responses associated with the progression from chronic disease to long-term inapparent infection. The results of these studies revealed over a 10(3)-fold difference in the steady-state levels of plasma viral RNA detected during long-term inapparent infection that correlated with the severity of chronic disease, indicating different levels of control of virus replication during long-term inapparent infections. Detailed analyses of antibody and cellular immune responses in all four ponies over the 3-year course of infection revealed a similar evolution during the first year postinfection of robust humoral and cellular immunity that then remained relatively constant during long-term inapparent infection. These observations indicate that immune parameters that have previously been correlated with EIAV vaccine protection fail to provide

  19. Transforming growth factor-beta promotes rhinovirus replication in bronchial epithelial cells by suppressing the innate immune response.

    Directory of Open Access Journals (Sweden)

    Nicole Bedke

    Full Text Available Rhinovirus (RV infection is a major cause of asthma exacerbations which may be due to a deficient innate immune response in the bronchial epithelium. We hypothesized that the pleiotropic cytokine, TGF-β, influences interferon (IFN production by primary bronchial epithelial cells (PBECs following RV infection. Exogenous TGF-β(2 increased RV replication and decreased IFN protein secretion in response to RV or double-stranded RNA (dsRNA. Conversely, neutralizing TGF-β antibodies decreased RV replication and increased IFN expression in response to RV or dsRNA. Endogenous TGF-β(2 levels were higher in conditioned media of PBECs from asthmatic donors and the suppressive effect of anti-TGF-β on RV replication was significantly greater in these cells. Basal SMAD-2 activation was reduced when asthmatic PBECs were treated with anti-TGF-β and this was accompanied by suppression of SOCS-1 and SOCS-3 expression. Our results suggest that endogenous TGF-β contributes to a suppressed IFN response to RV infection possibly via SOCS-1 and SOCS-3.

  20. The human parvovirus B19 non-structural protein 1 N-terminal domain specifically binds to the origin of replication in the viral DNA.

    Science.gov (United States)

    Tewary, Sunil Kumar; Zhao, Haiyan; Deng, Xuefeng; Qiu, Jianming; Tang, Liang

    2014-01-20

    The non-structural protein 1 (NS1) of human parvovirus B19 plays a critical role in viral DNA replication. Previous studies identified the origin of replication in the viral DNA, which contains four DNA elements, namely NSBE1 to NSBE4, that are required for optimal viral replication (Guan et al., 2009). Here we have demonstrated in vitro that the NS1 N-terminal domain (NS1N) binds to the origin of replication in a sequence-specific, length-dependent manner that requires NSBE1 and NSBE2, while NSBE3 and NSBE4 are dispensable. Mutagenesis analysis has identified nucleotides in NSBE1 and NSBE2 that are critical for NS1N binding. These results suggest that NS1 binds to the NSBE1-NSBE2 region in the origin of replication, while NSBE3 and NSBE4 may provide binding sites for potential cellular factors. Such a specialized nucleoprotein complex may enable NS1 to nick the terminal resolution site and separate DNA strands during replication. © 2013 Published by Elsevier Inc.

  1. Equine Herpesvirus Type 1 Enhances Viral Replication in CD172a+ Monocytic Cells upon Adhesion to Endothelial Cells.

    Science.gov (United States)

    Laval, Kathlyn; Favoreel, Herman W; Poelaert, Katrien C K; Van Cleemput, Jolien; Nauwynck, Hans J

    2015-11-01

    Equine herpesvirus type 1 (EHV-1) is a main cause of respiratory disease, abortion, and encephalomyelopathy in horses. Monocytic cells (CD172a(+)) are the main carrier cells of EHV-1 during primary infection and are proposed to serve as a "Trojan horse" to facilitate the dissemination of EHV-1 to target organs. However, the mechanism by which EHV-1 is transferred from CD172a(+) cells to endothelial cells (EC) remains unclear. The aim of this study was to investigate EHV-1 transmission between these two cell types. We hypothesized that EHV-1 employs specific strategies to promote the adhesion of infected CD172a(+) cells to EC to facilitate EHV-1 spread. Here, we demonstrated that EHV-1 infection of CD172a(+) cells resulted in a 3- to 5-fold increase in adhesion to EC. Antibody blocking experiments indicated that α4β1, αLβ2, and αVβ3 integrins mediated adhesion of infected CD172a(+) cells to EC. We showed that integrin-mediated phosphatidylinositol 3-kinase (PI3K) and ERK/MAPK signaling pathways were involved in EHV-1-induced CD172a(+) cell adhesion at early times of infection. EHV-1 replication was enhanced in adherent CD172a(+) cells, which correlates with the production of tumor necrosis factor alpha (TNF-α). In the presence of neutralizing antibodies, approximately 20% of infected CD172a(+) cells transferred cytoplasmic material to uninfected EC and 0.01% of infected CD172a(+) cells transmitted infectious virus to neighboring cells. Our results demonstrated that EHV-1 infection induces adhesion of CD172a(+) cells to EC, which enhances viral replication, but that transfer of viral material from CD172a(+) cells to EC is a very specific and rare event. These findings give new insights into the complex pathogenesis of EHV-1. Equine herpesvirus type 1 (EHV-1) is a highly prevalent pathogen worldwide, causing frequent outbreaks of abortion and myeloencephalopathy, even in vaccinated horses. After primary replication in the respiratory tract, EHV-1 disseminates

  2. The human adenovirus type 5 E1B 55 kDa protein obstructs inhibition of viral replication by type I interferon in normal human cells.

    Directory of Open Access Journals (Sweden)

    Jasdave S Chahal

    Full Text Available Vectors derived from human adenovirus type 5, which typically lack the E1A and E1B genes, induce robust innate immune responses that limit their therapeutic efficacy. We reported previously that the E1B 55 kDa protein inhibits expression of a set of cellular genes that is highly enriched for those associated with anti-viral defense and immune responses, and includes many interferon-sensitive genes. The sensitivity of replication of E1B 55 kDa null-mutants to exogenous interferon (IFN was therefore examined in normal human fibroblasts and respiratory epithelial cells. Yields of the mutants were reduced at least 500-fold, compared to only 5-fold, for wild-type (WT virus replication. To investigate the mechanistic basis of such inhibition, the accumulation of viral early proteins and genomes was compared by immunoblotting and qPCR, respectively, in WT- and mutant-infected cells in the absence or presence of exogenous IFN. Both the concentration of viral genomes detected during the late phase and the numbers of viral replication centers formed were strongly reduced in IFN-treated cells in the absence of the E1B protein, despite production of similar quantities of viral replication proteins. These defects could not be attributed to degradation of entering viral genomes, induction of apoptosis, or failure to reorganize components of PML nuclear bodies. Nor was assembly of the E1B- and E4 Orf6 protein- E3 ubiquitin ligase required to prevent inhibition of viral replication by IFN. However, by using RT-PCR, the E1B 55 kDa protein was demonstrated to be a potent repressor of expression of IFN-inducible genes in IFN-treated cells. We propose that a primary function of the previously described transcriptional repression activity of the E1B 55 kDa protein is to block expression of IFN- inducible genes, and hence to facilitate formation of viral replication centers and genome replication.

  3. Curaxin CBL0100 Blocks HIV-1 Replication and Reactivation through Inhibition of Viral Transcriptional Elongation.

    Science.gov (United States)

    Jean, Maxime J; Hayashi, Tsuyoshi; Huang, Huachao; Brennan, Justin; Simpson, Sydney; Purmal, Andrei; Gurova, Katerina; Keefer, Michael C; Kobie, James J; Santoso, Netty G; Zhu, Jian

    2017-01-01

    Despite combination antiretroviral therapy (cART), acquired immunodeficiency syndrome (AIDS), predominantly caused by the human immunodeficiency virus type 1 (HIV-1), remains incurable. The barrier to a cure lies in the virus' ability to establish a latent infection in HIV/AIDS patients. Unsurprisingly, efforts for a sterilizing cure have focused on the "shock and kill" strategy using latency-reversing agents (LRAs) to complement cART in order to eliminate these latent reservoirs. However, this method faces numerous challenges. Recently, the "block and lock" strategy has been proposed. It aims to reinforce a deep state of latency and prevent sporadic reactivation ("blip") of HIV-1 using latency-promoting agents (LPAs) for a functional cure. Our studies of curaxin 100 (CBL0100), a small-molecule targeting the facilitates chromatin transcription (FACT) complex, show that it blocks both HIV-1 replication and reactivation in in vitro and ex vivo models of HIV-1. Mechanistic investigation elucidated that CBL0100 preferentially targets HIV-1 transcriptional elongation and decreases the occupancy of RNA Polymerase II (Pol II) and FACT at the HIV-1 promoter region. In conclusion, CBL0100 is a newly identified inhibitor of HIV-1 transcription that can be used as an LPA in the "block and lock" cure strategy.

  4. Morphological correlates of genital HPV infection: Viral replication, transcription and gene expression

    International Nuclear Information System (INIS)

    Crum, C.P.; Friedman, D.; Nuovo, G.; Silverstein, S.J.

    1987-01-01

    Current studies indicate a strong correlation between specific morphological changes and the presence of certain HPV strains in precancerous squamous epithelium of the cervix, vulva and vagina. HPV type 16 is the most commonly detected HPV type in cervical lesions in our experience, and 85% of these lesions exhibit some morphological features associated with aneuploid epithelium (CIN). However, over 50% of these lesions containing HPV 16 DNA exhibit, in addition, foci of epithelium indistinguishable from condyloma, although in our experience, only one HPV type(16) is detected in the majority of these lesions. DNA-DNA in situ hybridization analysis of these lesions containing HPV 16 DNA has demonstrated nucleic acids in areas resembling both condyloma and CIN, with the greatest concentration in mature cells containing cytoplasmic maturation. Ten percent of lesions containing HPV 16 produce detectable capsid antigens, and we have confirmed the presence of these antigens in the same areas which hybridize in-situ for HPV DNA. Recent studies using biotin and S-35 labeled RNa probes constructed in GEM-1 vectors indicate that early HPV genes are expressed primarily in the upper (more mature) regions of the neoplastic epithelium. Thus maturation appears to exert a positive influence on a variety of HPV functions in neoplastic epithelium, including DNA replication, early and late gene expression. It is possible that patterns of gene expression may vary between lesions associated with different HPV types or different morphologies. This possibility is being explored

  5. Curaxin CBL0100 Blocks HIV-1 Replication and Reactivation through Inhibition of Viral Transcriptional Elongation

    Directory of Open Access Journals (Sweden)

    Maxime J. Jean

    2017-10-01

    Full Text Available Despite combination antiretroviral therapy (cART, acquired immunodeficiency syndrome (AIDS, predominantly caused by the human immunodeficiency virus type 1 (HIV-1, remains incurable. The barrier to a cure lies in the virus' ability to establish a latent infection in HIV/AIDS patients. Unsurprisingly, efforts for a sterilizing cure have focused on the “shock and kill” strategy using latency-reversing agents (LRAs to complement cART in order to eliminate these latent reservoirs. However, this method faces numerous challenges. Recently, the “block and lock” strategy has been proposed. It aims to reinforce a deep state of latency and prevent sporadic reactivation (“blip” of HIV-1 using latency-promoting agents (LPAs for a functional cure. Our studies of curaxin 100 (CBL0100, a small-molecule targeting the facilitates chromatin transcription (FACT complex, show that it blocks both HIV-1 replication and reactivation in in vitro and ex vivo models of HIV-1. Mechanistic investigation elucidated that CBL0100 preferentially targets HIV-1 transcriptional elongation and decreases the occupancy of RNA Polymerase II (Pol II and FACT at the HIV-1 promoter region. In conclusion, CBL0100 is a newly identified inhibitor of HIV-1 transcription that can be used as an LPA in the “block and lock” cure strategy.

  6. Transcriptional Changes during Naturally Acquired Zika Virus Infection Render Dendritic Cells Highly Conducive to Viral Replication.

    Science.gov (United States)

    Sun, Xiaoming; Hua, Stephane; Chen, Hsiao-Rong; Ouyang, Zhengyu; Einkauf, Kevin; Tse, Samantha; Ard, Kevin; Ciaranello, Andrea; Yawetz, Sigal; Sax, Paul; Rosenberg, Eric S; Lichterfeld, Mathias; Yu, Xu G

    2017-12-19

    Although dendritic cells are among the human cell population best equipped for cell-intrinsic antiviral immune defense, they seem highly susceptible to infection with the Zika virus (ZIKV). Using highly purified myeloid dendritic cells isolated from individuals with naturally acquired acute infection, we here show that ZIKV induces profound perturbations of transcriptional signatures relative to healthy donors. Interestingly, we noted a remarkable downregulation of antiviral interferon-stimulated genes and innate immune sensors, suggesting that ZIKV can actively suppress interferon-dependent immune responses. In contrast, several host factors known to support ZIKV infection were strongly upregulated during natural ZIKV infection; these transcripts included AXL, the main entry receptor for ZIKV; SOCS3, a negative regulator of ISG expression; and IDO-1, a recognized inducer of regulatory T cell responses. Thus, during in vivo infection, ZIKV can transform the transcriptome of dendritic cells in favor of the virus to render these cells highly conducive to ZIKV infection. Published by Elsevier Inc.

  7. Mutational Analysis of the Hypervariable Region of Hepatitis E Virus Reveals Its Involvement in the Efficiency of Viral RNA Replication

    OpenAIRE

    Pudupakam, R. S.; Kenney, Scott P.; Córdoba, Laura; Huang, Yao-Wei; Dryman, Barbara A.; LeRoith, Tanya; Pierson, F. William; Meng, Xiang-Jin

    2011-01-01

    The RNA genome of the hepatitis E virus (HEV) contains a hypervariable region (HVR) in ORF1 that tolerates small deletions with respect to infectivity. To further investigate the role of the HVR in HEV replication, we constructed a panel of mutants with overlapping deletions in the N-terminal, central, and C-terminal regions of the HVR by using a genotype 1 human HEV luciferase replicon and analyzed the effects of deletions on viral RNA replication in Huh7 cells. We found that the replication...

  8. Variants in host viral replication cycle genes are associated with heterosexual HIV-1 acquisition in Africans.

    Science.gov (United States)

    Bigham, Abigail W; Mackelprang, Romel D; Celum, Connie; De Bruyn, Guy; Beima-Sofie, Kristin; John-Stewart, Grace; Ronald, Allan; Mugo, Nelly R; Buckingham, Kati; Bamshad, Michael J; Mullins, James I; McElrath, M J; Lingappa, Jairam R

    2014-06-01

    We evaluated genetic variants in 51 candidate genes encoding proteins that interact with HIV-1 during the virus life cycle for association with HIV-1 outcomes in an African cohort. Using a nested case-control study within a cohort of heterosexual HIV-1-serodiscordant couples, we genotyped 475 haplotype-tagging single-nucleotide polymorphisms (tagSNPs) and 18 SNPs previously associated with HIV-1 transmission and/or progression (candidate SNPs) in 51 host genes. We used logistic and Cox proportional hazard regression with adjustment for sex, age, and population stratification to detect SNP associations with HIV-1 acquisition, plasma HIV-1 set point, and a composite measure of HIV-1 disease progression. Significant thresholds for tagSNP, but not candidate SNP, associations were subjected to Bonferroni correction for multiple testing. We evaluated 491 HIV-1-infected and 335 HIV-1-uninfected individuals for 493 SNPs, 459 of which passed quality control filters. Candidate SNP PPIA rs8177826 and tagSNP SMARCB1 rs6003904 were significantly associated with HIV-1 acquisition risk (odds ratio = 0.14, P = 0.03, and odds ratio = 2.11, Pcorr = 0.01, respectively). Furthermore, the TT genotype for CCR5 rs1799988 was associated with a mean 0.2 log10 copies per milliliter lower plasma HIV-1 RNA set point (P = 0.04). We also identified significant associations with HIV-1 disease progression for variants in FUT2 and MBL2. Using a targeted gene approach, we identified variants in host genes whose protein products interact with HIV-1 during the virus replication cycle and were associated with HIV-1 outcomes in this African cohort.

  9. The impact of early immune destruction on the kinetics of postacute viral replication in rhesus monkey infected with the simian-human immunodeficiency virus 89.6P

    International Nuclear Information System (INIS)

    Zhang Zhiqiang; Schleif, William A.; Casimiro, Danilo R.; Handt, Larry; Chen, Minchun; Davies, Mary-Ellen; Liang Xiaoping; Fu Tongming; Tang Aimin; Wilson, Keith A.; McElhaugh, Michael; Carella, Anthony; Tan, Charles; Connolly, Brett; Hill, Susan; Klein, Hilton; Emini, Emilio A.; Shiver, John W.

    2004-01-01

    Set-point viral load is positively correlated with the extent of initial viral replication in pathogenic simian-human immunodeficiency virus (SHIV) infection. To elucidate the mechanisms underlying the correlation, we conducted a systematic investigation in rhesus monkeys infected with the highly pathogenic SHIV 89.6P. This model is widely used in the preclinical evaluation of AIDS vaccine candidates and a thorough understanding of the model's biology is important to the proper interpretation of these evaluations. We found that the levels of peak viremia were positively correlated not only with the levels of set-point viremia but, importantly, with the extent of initial overall immune destruction as indicated by the degree of CD4 + T cell depletion and lymph node germinal center (GC) formation. The extent of initial overall immune destruction was inversely correlated with subsequent development and maintenance of virus-specific cellular and humoral immune responses. Thus, these data suggest that the extent of early immune damage determines the development and durability of virus-specific immunity, thereby playing a critical role in establishing the levels of set-point viral replication in SHIV infection. Vaccines that limit both the initial viral replication and the extent of early immune damage will therefore mediate long-term virus replication control and mitigation of long-term immune destruction in this model of immunodeficiency virus infection

  10. Detection of Porcine Circovirus Type 2 and Viral Replication by In Situ Hybridization in Primary Lymphoid Organs From Naturally and Experimentally Infected Pigs

    DEFF Research Database (Denmark)

    Hansen, Mette Sif; Segalés, J.; Fernandes, L.

    2013-01-01

    was not detected in the experimentally PCV2-inoculated pigs or the control animals. Among the PMWS-affected pigs, 19 of 20 (95%) thymuses were positive for PCV2 by CP ISH, and 7 of 19 (37%) of these also supported viral replication. By CP ISH, PCV2 was detected in 16 of 33 (48%) bone marrow samples, and 5 of 16...

  11. Regular Marijuana Use is Associated with Poor Viral Suppression in HIV-Infected Adolescents and Young Adults.

    Science.gov (United States)

    Thompson, Amelia B; Gillespie, Scott E; Hood, Jasper; Thomas-Seaton, LaTeshia; Hussen, Sophia A; Camacho-Gonzalez, Andres F

    2018-04-01

    There is a paucity of data regarding the impact of drug use on HIV suppression and care retention among adolescents and young adults (AYAs). We recruited a clinic-based sample of HIV infected AYAs to assess the prevalence of self-reported drug use. Clinical data, including retention and viral suppression, were abstracted from the electronic medical record. Logistic regression was used to evaluate marijuana and illicit drug use associations and to identify other risk factors. Of 200 participants (mean age 21, 2.4 years, 69% horizontally infected), 46% reported current drug use, with marijuana as the most commonly used drug. Any illicit drug use (aOR 1.99, 95% CI 1.06-3.73, p = 0.032) and lower education (aOR 2.11, 95% CI 1.09-4.08, p = 0.046) were associated with poor viral suppression in multivariable analyses. Considering marijuana use only, an association with poor viral suppression was more pronounced (aOR 2.10, 95% CI 1.12-3.94, p = 0.021). Drug use did not have a significant association with retention in care, but AYAs who were retained in HIV care were less likely to have poorly suppressed HIV (aOR 0.22, 95% CI 0.10-0.49, p < 0.001). High prevalence of marijuana use among HIV infected AYAs, and its association with poorly suppressed HIV, demonstrates the need for intervention strategies to decrease its consumption.

  12. The N terminus of the influenza B virus nucleoprotein is essential for virus viability, nuclear localization, and optimal transcription and replication of the viral genome.

    Science.gov (United States)

    Sherry, Lee; Smith, Matt; Davidson, Sophie; Jackson, David

    2014-11-01

    The nucleoprotein (NP) of influenza viruses is a multifunctional protein with essential roles throughout viral replication. Despite influenza A and B viruses belonging to separate genera of the Orthomyxoviridae family, their NP proteins share a relatively high level of sequence conservation. However, NP of influenza B viruses (BNP) contains an evolutionarily conserved N-terminal 50-amino-acid extension that is absent from NP of influenza A viruses. There is conflicting evidence as to the functions of the BNP N-terminal extension; however, this has never been assessed in the context of viral infection. We have used reverse genetics to assess the significance of this region on the functions of BNP and virus viability. The truncation of more than three amino acids prevented virus recovery, suggesting that the N-terminal extension is essential for virus viability. Mutational analysis indicated that multiple regions of the protein are involved in the nuclear localization of BNP, with the entire N-terminal extension required for this to function efficiently. Viruses containing mutations in the first 10 residues of BNP demonstrated few differences in nuclear localization; however, the viruses exhibited significant reductions in viral mRNA transcription and genome replication, resulting in significantly attenuated phenotypes. Mutations introduced to ablate a previously reported nuclear localization signal also resulted in a significant decrease in mRNA production during early stages of viral replication. Overall, our results demonstrate that the N-terminal extension of BNP is essential to virus viability not only for directing nuclear localization of BNP but also for regulating viral mRNA transcription and genome replication. The multifunctional NP of influenza viruses has roles throughout the viral replication cycle; therefore, it is essential for virus viability. Despite high levels of homology between the NP of influenza A and B viruses, the NP of influenza B virus

  13. Barrier to auto integration factor becomes dephosphorylated during HSV-1 Infection and Can Act as a host defense by impairing viral DNA replication and gene expression.

    Science.gov (United States)

    Jamin, Augusta; Thunuguntla, Prasanth; Wicklund, April; Jones, Clinton; Wiebe, Matthew S

    2014-01-01

    BAF (Barrier to Autointegration Factor) is a highly conserved DNA binding protein that senses poxviral DNA in the cytoplasm and tightly binds to the viral genome to interfere with DNA replication and transcription. To counteract BAF, a poxviral-encoded protein kinase phosphorylates BAF, which renders BAF unable to bind DNA and allows efficient viral replication to occur. Herein, we examined how BAF phosphorylation is affected by herpes simplex virus type 1 (HSV-1) infection and tested the ability of BAF to interfere with HSV-1 productive infection. Interestingly, we found that BAF phosphorylation decreases markedly following HSV-1 infection. To determine whether dephosphorylated BAF impacts HSV-1 productive infection, we employed cell lines stably expressing a constitutively unphosphorylated form of BAF (BAF-MAAAQ) and cells overexpressing wild type (wt) BAF for comparison. Although HSV-1 production in cells overexpressing wtBAF was similar to that in cells expressing no additional BAF, viral growth was reduced approximately 80% in the presence of BAF-MAAAQ. Experiments were also performed to determine the mechanism of the antiviral activity of BAF with the following results. BAF-MAAAQ was localized to the nucleus, whereas wtBAF was dispersed throughout cells prior to infection. Following infection, wtBAF becomes dephosphorylated and relocalized to the nucleus. Additionally, BAF was associated with the HSV-1 genome during infection, with BAF-MAAAQ associated to a greater extent than wtBAF. Importantly, unphosphorylated BAF inhibited both viral DNA replication and gene expression. For example, expression of two regulatory proteins, ICP0 and VP16, were substantially reduced in cells expressing BAF-MAAAQ. However, other viral genes were not dramatically affected suggesting that expression of certain viral genes can be differentially regulated by unphosphorylated BAF. Collectively, these results suggest that BAF can act in a phosphorylation-regulated manner to impair

  14. HIV-associated neurodevelopmental delay: prevalence, predictors and persistence in relation to antiretroviral therapy initiation and viral suppression.

    Science.gov (United States)

    Strehlau, R; Kuhn, L; Abrams, E J; Coovadia, A

    2016-11-01

    HIV infection in infancy may influence the developing brain, leading to adverse neurodevelopmental consequences. We aim to describe neurodevelopmental characteristics of a cohort of HIV-infected infants and young children prior to antiretroviral therapy (ART) initiation and after achieving viral suppression. As part of the Neverest 2 trial, 195 HIV-infected children under 2 years of age were assessed using the Ages and Stages Questionnaire (ASQ) prior to ART initiation and at subsequent age-appropriate time points after ART had been started. The ASQ is a simple screening questionnaire used to identify children at risk of neurodevelopmental delays. Questionnaires completed by the parent/caregiver assess neurodevelopmental functioning in five domains: communication, gross motor, fine motor, problem solving and personal-social. Median age pre-ART was 8.8 months (range 2.2-24.9) and 53.9% were male. Mean time to viral suppression was 9.4 months (range 5.9-14.5). Compared with pre-ART better outcomes were reported at time of viral suppression with a lower proportion of children failing the gross motor (31.5% vs. 13%, p = 0.0002), fine motor (21.3% vs. 10.2%, p = 0.017), problem solving (26.9% vs. 9.3%, p = 0.0003) and personal-social (19.6% vs. 7.4%, p = 0.019) domains. However, there was no change in the communication domain (14.8% vs. 12.0%, p = 0.6072). Although achieving viral suppression on ART resulted in significant improvements in markers of neurodevelopmental function of young HIV-infected children, potential neurodevelopmental delays still persisted in a large proportion. Further interventions are needed to limit potential disabilities and maximize developmental outcomes. © 2016 John Wiley & Sons Ltd.

  15. A Novel, Highly Selective Inhibitor of Pestivirus Replication That Targets the Viral RNA-Dependent RNA Polymerase

    Science.gov (United States)

    Paeshuyse, Jan; Leyssen, Pieter; Mabery, Eric; Boddeker, Nina; Vrancken, Robert; Froeyen, Matheus; Ansari, Israrul H.; Dutartre, Hélène; Rozenski, Jef; Gil, Laura H. V. G.; Letellier, Carine; Lanford, Robert; Canard, Bruno; Koenen, Frank; Kerkhofs, Pierre; Donis, Ruben O.; Herdewijn, Piet; Watson, Julia; De Clercq, Erik; Puerstinger, Gerhard; Neyts, Johan

    2006-01-01

    We report on the highly potent and selective antipestivirus activity of 5-[(4-bromophenyl)methyl]-2-phenyl-5H-imidazo[4,5-c]pyridine (BPIP). The 50% effective concentration (EC50) for inhibition of bovine viral diarrhea virus (BVDV)-induced cytopathic effect formation was 0.04 ± 0.01 μM. Comparable reduction of viral RNA synthesis (EC50 = 0.12 ± 0.02 μM) and production of infectious virus (EC50 = 0.074 ± 0.003 μM) were observed. The selectivity index (ratio of 50% cytostatic concentration/EC50) of BPIP was ∼2,000. BPIP was inactive against the hepatitis C virus subgenomic replicon and yellow fever virus but demonstrated weak activity against GB virus. Drug-resistant mutants were at least 300-fold less susceptible to BPIP than wild-type virus; showed cross-resistance to N-propyl-N-[2-(2H-1,2,4-triazino[5,6-b]indol-3-ylthio)ethyl]-1-propanamine (VP32947), and carried the F224S mutation in the viral RNA-dependent RNA polymerase (RdRp). When the F224S mutation was introduced into an infectious clone, the drug-resistant phenotype was obtained. BPIP did not inhibit the in vitro activity of recombinant BVDV RdRp, but did inhibit the activity of replication complexes (RCs). Computational docking revealed that F224 is located at the top of the finger domain of the polymerase. Docking of BPIP in the crystal structure of the BVDV RdRp revealed aromatic ring stacking, some hydrophobic contacts, and a hydrogen bond. Since two structurally unrelated compounds, i.e., BPIP and VP32947, target the same region of the BVDV RdRp, this position may be expected to be critical in the functioning of the polymerase or assembly of the RC. The potential of BPIP for the treatment of pestivirus and hepacivirus infections is discussed. PMID:16352539

  16. Someone to count on: social support as an effect modifier of viral load suppression in a prospective cohort study.

    Science.gov (United States)

    Friedman, M Reuel; Coulter, Robert W S; Silvestre, Anthony J; Stall, Ron; Teplin, Linda; Shoptaw, Steve; Surkan, Pamela J; Plankey, Michael W

    2017-04-01

    Though functional social support has been shown to serve as a protective factor for HIV viral load suppression in other populations, scant research has examined this relationship among men who have sex with men (MSM) in the United States. We assessed characteristics of social support, effects of social support on HIV viral load, and moderation by social support of the relationship between psychosocial indicators of a synergistic epidemic (syndemic) and HIV viral load. We analyzed longitudinal data from HIV-positive MSM using antiretroviral therapy who were enrolled in the Multicenter AIDS Cohort Study between 2002 and 2009 (n = 712). First, we conducted reliability assessments of a one-item social support measure. Then, we conducted a series of generalized longitudinal mixed models to assess our research questions. Moderation was assessed using an interaction term. A three-level (low/medium/high) social support variable demonstrated high reliability (intraclass correlation coefficients  = 0.72; 95% CI: 0.70, 0.75). Black and Hispanic MSM reported lower social support than their White counterparts (p social support (p social support (p social support levels were associated with greater viral load suppression and lower viral load means (p Social support moderated the relationships between syndemic and HIV viral load (p HIV-positive MSM, particularly those of color, may benefit greatly from interventions that can successfully boost functional social support. Creating strengths-based interventions may also have particularly high impact among HIV-positive MSM with the highest psychosocial burdens.

  17. Differential responses of Africanized and European honey bees (Apis mellifera) to viral replication following mechanical transmission or Varroa destructor parasitism.

    Science.gov (United States)

    Hamiduzzaman, Mollah Md; Guzman-Novoa, Ernesto; Goodwin, Paul H; Reyes-Quintana, Mariana; Koleoglu, Gun; Correa-Benítez, Adriana; Petukhova, Tatiana

    2015-03-01

    For the first time, adults and brood of Africanized and European honey bees (Apis mellifera) were compared for relative virus levels over 48 h following Varroa destructor parasitism or injection of V. destructor homogenate. Rates of increase of deformed wing virus (DWV) for Africanized versus European bees were temporarily lowered for 12h with parasitism and sustainably lowered over the entire experiment (48 h) with homogenate injection in adults. The rates were also temporarily lowered for 24h with parasitism but were not affected by homogenate injection in brood. Rates of increase of black queen cell virus (BQCV) for Africanized versus European bees were similar with parasitism but sustainably lowered over the entire experiment with homogenate injection in adults and were similar for parasitism and homogenate injection in brood. Analyses of sac brood bee virus and Israeli acute paralysis virus were limited as detection did not occur after both homogenate injection and parasitism treatment, or levels were not significantly higher than those following control buffer injection. Lower rates of replication of DWV and BQCV in Africanized bees shows that they may have greater viral resistance, at least early after treatment. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. BRD4 Phosphorylation Regulates HPV E2-Mediated Viral Transcription, Origin Replication, and Cellular MMP-9 Expression

    Directory of Open Access Journals (Sweden)

    Shwu-Yuan Wu

    2016-08-01

    Full Text Available Post-translational modification can modulate protein conformation and alter binding partner recruitment within gene regulatory regions. Here, we report that bromodomain-containing protein 4 (BRD4, a transcription co-factor and chromatin regulator, uses a phosphorylation-induced switch mechanism to recruit E2 protein encoded by cancer-associated human papillomavirus (HPV to viral early gene and cellular matrix metalloproteinase-9 (MMP-9 promoters. Enhanced MMP-9 expression, induced upon keratinocyte differentiation, occurs via BRD4-dependent recruitment of active AP-1 and NF-κB to their target sequences. This is triggered by replacement of AP-1 family members JunB and JunD by c-Jun and by re-localization of NF-κB from the cytoplasm to the nucleus. In addition, BRD4 phosphorylation is critical for E2- and origin-dependent HPV DNA replication. A class of phospho-BRD4-targeting compounds, distinct from the BET bromodomain inhibitors, effectively blocks BRD4 phosphorylation-specific functions in transcription and factor recruitment.

  19. PolyC-binding protein 1 interacts with 5'-untranslated region of enterovirus 71 RNA in membrane-associated complex to facilitate viral replication.

    Directory of Open Access Journals (Sweden)

    Zhen Luo

    Full Text Available Enterovirus 71 (EV71 is one causative agent of hand, foot, and mouth disease (HFMD, which may lead to severe neurological disorders and mortality in children. EV71 genome is a positive single-stranded RNA containing a single open reading frame (ORF flanked by 5'-untranslated region (5'UTR and 3'UTR. The 5'UTR is fundamentally important for virus replication by interacting with cellular proteins. Here, we revealed that poly(C-binding protein 1 (PCBP1 specifically binds to the 5'UTR of EV71. Detailed studies indicated that the RNA-binding K-homologous 1 (KH1 domain of PCBP1 is responsible for its binding to the stem-loop I and IV of EV71 5'UTR. Interestingly, we revealed that PCBP1 is distributed in the nucleus and cytoplasm of uninfected cells, but mainly localized in the cytoplasm of EV71-infected cells due to interaction and co-localization with the viral RNA. Furthermore, sub-cellular distribution analysis showed that PCBP1 is located in ER-derived membrane, in where virus replication occurred in the cytoplasm of EV71-infected cells, suggesting PCBP1 is recruited in a membrane-associated replication complex. In addition, we found that the binding of PCBP1 to 5'UTR resulted in enhancing EV71 viral protein expression and virus production so as to facilitate viral replication. Thus, we revealed a novel mechanism in which PCBP1 as a positive regulator involved in regulation of EV71 replication in the host specialized membrane-associated replication complex, which provides an insight into cellular factors involved in EV71 replication.

  20. Type I and Type II Interferon Coordinately Regulate Suppressive Dendritic Cell Fate and Function during Viral Persistence.

    Directory of Open Access Journals (Sweden)

    Cameron R Cunningham

    2016-01-01

    Full Text Available Persistent viral infections are simultaneously associated with chronic inflammation and highly potent immunosuppressive programs mediated by IL-10 and PDL1 that attenuate antiviral T cell responses. Inhibiting these suppressive signals enhances T cell function to control persistent infection; yet, the underlying signals and mechanisms that program immunosuppressive cell fates and functions are not well understood. Herein, we use lymphocytic choriomeningitis virus infection (LCMV to demonstrate that the induction and functional programming of immunosuppressive dendritic cells (DCs during viral persistence are separable mechanisms programmed by factors primarily considered pro-inflammatory. IFNγ first induces the de novo development of naive monocytes into DCs with immunosuppressive potential. Type I interferon (IFN-I then directly targets these newly generated DCs to program their potent T cell immunosuppressive functions while simultaneously inhibiting conventional DCs with T cell stimulating capacity. These mechanisms of monocyte conversion are constant throughout persistent infection, establishing a system to continuously interpret and shape the immunologic environment. MyD88 signaling was required for the differentiation of suppressive DCs, whereas inhibition of stimulatory DCs was dependent on MAVS signaling, demonstrating a bifurcation in the pathogen recognition pathways that promote distinct elements of IFN-I mediated immunosuppression. Further, a similar suppressive DC origin and differentiation was also observed in Mycobacterium tuberculosis infection, HIV infection and cancer. Ultimately, targeting the underlying mechanisms that induce immunosuppression could simultaneously prevent multiple suppressive signals to further restore T cell function and control persistent infections.

  1. Type I and Type II Interferon Coordinately Regulate Suppressive Dendritic Cell Fate and Function during Viral Persistence

    Science.gov (United States)

    Cunningham, Cameron R.; Champhekar, Ameya; Tullius, Michael V.; Dillon, Barbara Jane; Zhen, Anjie; de la Fuente, Justin Rafael; Herskovitz, Jonathan; Elsaesser, Heidi; Snell, Laura M.; Wilson, Elizabeth B.; de la Torre, Juan Carlos; Kitchen, Scott G.; Horwitz, Marcus A.; Bensinger, Steven J.; Smale, Stephen T.; Brooks, David G.

    2016-01-01

    Persistent viral infections are simultaneously associated with chronic inflammation and highly potent immunosuppressive programs mediated by IL-10 and PDL1 that attenuate antiviral T cell responses. Inhibiting these suppressive signals enhances T cell function to control persistent infection; yet, the underlying signals and mechanisms that program immunosuppressive cell fates and functions are not well understood. Herein, we use lymphocytic choriomeningitis virus infection (LCMV) to demonstrate that the induction and functional programming of immunosuppressive dendritic cells (DCs) during viral persistence are separable mechanisms programmed by factors primarily considered pro-inflammatory. IFNγ first induces the de novo development of naive monocytes into DCs with immunosuppressive potential. Type I interferon (IFN-I) then directly targets these newly generated DCs to program their potent T cell immunosuppressive functions while simultaneously inhibiting conventional DCs with T cell stimulating capacity. These mechanisms of monocyte conversion are constant throughout persistent infection, establishing a system to continuously interpret and shape the immunologic environment. MyD88 signaling was required for the differentiation of suppressive DCs, whereas inhibition of stimulatory DCs was dependent on MAVS signaling, demonstrating a bifurcation in the pathogen recognition pathways that promote distinct elements of IFN-I mediated immunosuppression. Further, a similar suppressive DC origin and differentiation was also observed in Mycobacterium tuberculosis infection, HIV infection and cancer. Ultimately, targeting the underlying mechanisms that induce immunosuppression could simultaneously prevent multiple suppressive signals to further restore T cell function and control persistent infections. PMID:26808628

  2. Fluorescent reporter signals, EGFP and DsRed, encoded in HIV-1 facilitate the detection of productively infected cells and cell-associated viral replication levels

    Directory of Open Access Journals (Sweden)

    Kazutaka eTerahara

    2012-01-01

    Full Text Available Flow cytometric analysis is a reliable and convenient method for investigating molecules at the single cell level. Previously, recombinant human immunodeficiency virus type 1 (HIV-1 strains were constructed that express a fluorescent reporter, either enhanced green fluorescent protein or DsRed, which allow the monitoring of HIV-1-infected cells by flow cytometry. The present study further investigated the potential of these recombinant viruses in terms of whether the HIV-1 fluorescent reporters would be helpful in evaluating viral replication based on fluorescence intensity. When primary CD4+ T cells were infected with recombinant viruses, the fluorescent reporter intensity measured by flow cytometry was associated with the level of CD4 downmodulation and Gag p24 expression in infected cells. Interestingly, some HIV-1-infected cells, in which CD4 was only moderately downmodulated, were reporter-positive but Gag p24-negative. Furthermore, when the activation status of primary CD4+ T cells was modulated by T cell receptor-mediated stimulation, we confirmed the preferential viral production upon strong stimulation and showed that the intensity of the fluorescent reporter within a proportion of HIV-1-infected cells was correlated with the viral replication level. These findings indicate that a fluorescent reporter encoded within HIV-1 is useful for the sensitive detection of productively-infected cells at different stages of infection and for evaluating cell-associated viral replication at the single cell level.

  3. SCFCyclin F-dependent degradation of CDC6 suppresses DNA re-replication

    DEFF Research Database (Denmark)

    Walter, David; Hoffmann, Saskia; Komseli, Eirini-Stavroula

    2016-01-01

    origin licensing, however, it is poorly understood how CDC6 activity is constrained in higher eukaryotes. Here we report that the SCF(Cyclin F) ubiquitin ligase complex prevents DNA re-replication by targeting CDC6 for proteasomal degradation late in the cell cycle. We show that CDC6 and Cyclin F...... interact through defined sequence motifs that promote CDC6 ubiquitylation and degradation. Absence of Cyclin F or expression of a stable mutant of CDC6 promotes re-replication and genome instability in cells lacking the CDT1 inhibitor Geminin. Together, our work reveals a novel SCF(Cyclin F...

  4. Switching tenofovir/emtricitabine plus lopinavir/r to raltegravir plus Darunavir/r in patients with suppressed viral load did not result in improvement of renal function but could sustain viral suppression: a randomized multicenter trial.

    Directory of Open Access Journals (Sweden)

    Takeshi Nishijima

    Full Text Available BACKGROUND: Whether tenofovir nephrotoxicity is reversible after its withdrawal is unknown. Furthermore, there are no data on the viral efficacy of raltegravir (RAL plus ritonavir-boosted Darunavir (DRV/r in patients with suppressed viral load. METHODS: This multicenter, randomized trial compared renal function and viral efficacy in patients with suppressed viral load treated with RAL+DRV/r and ritonavir-boosted lopinavir (LPV/r plus tenofovir/emtricitabine (TVD, who had been previously on LPV/r+TVD. The primary endpoint was the proportion of patients with >10% improvement in estimated glomerular filtration rate (eGFR at 48 weeks calculated with Cockcroft-Gault equation. RESULTS: 58 randomized and treatment-exposed patients were analyzed (28 on RAL+DRV/r and 30 on LPV/r+TVD. Greater than 10% improvement in eGFR was noted in 6 (25% out of 24 with RAL+DRV/r and 3 (11% of 28 with LPV/r+TVD, and the difference was not statistically significant (p=0.272, 95% CI -0.067 to 0.354. Sensitivity analyses using three other equations for eGFR showed the same results. Urinary β2 microglobulin, a sensitive marker of tenofovir tubulopathy, significantly improved with RAL+DRV/r than with LPV/r+TVD (-271 versus -64 µg/gCr, p=0.026. Per protocol analysis showed that the HIV-RNA was 10% improvement in renal function among those with relatively preserved eGFR. However, the switch improved urinary β2 microglobulin, suggesting that discontinuation of TDF might be beneficial in the long-term. RAL+DRV/r showed favorable viral efficacy in patients with suppressed viral load. TRIAL REGISTRATION: ClinicalTrials.gov NCT01294761 http://clinicaltrials.gov/ct2/show/NCT01294761?term=SPARE&rank=2, Umin Clinical Trials Registry UMIN000005116 http://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000006083&language=J.

  5. The novel immunosuppressive protein kinase C inhibitor sotrastaurin has no pro-viral effects on the replication cycle of hepatitis B or C virus.

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    Thomas von Hahn

    Full Text Available The pan-protein kinase C (PKC inhibitor sotrastaurin (AEB071 is a novel immunosuppressant currently in phase II trials for immunosuppression after solid organ transplantation. Besides T-cell activation, PKC affects numerous cellular processes that are potentially important for the replication of hepatitis B virus (HBV and hepatitis C virus (HCV, major blood-borne pathogens prevalent in solid organ transplant recipients. This study uses state of the art virological assays to assess the direct, non-immune mediated effects of sotrastaurin on HBV and HCV. Most importantly, sotrastaurin had no pro-viral effect on either HBV or HCV. In the presence of high concentrations of sotrastaurin, well above those used clinically and close to levels where cytotoxic effects become detectable, there was a reduction of HCV and HBV replication. This reduction is very likely due to cytotoxic and/or anti-proliferative effects rather than direct anti-viral activity of the drug. Replication cycle stages other than genome replication such as viral cell entry and spread of HCV infection directly between adjacent cells was clearly unaffected by sotrastaurin. These data support the evaluation of sotrastaurin in HBV and/or HCV infected transplant recipients.

  6. The Oncogenic Small Tumor Antigen of Merkel Cell Polyomavirus Is an Iron-Sulfur Cluster Protein That Enhances Viral DNA Replication.

    Science.gov (United States)

    Tsang, Sabrina H; Wang, Ranran; Nakamaru-Ogiso, Eiko; Knight, Simon A B; Buck, Christopher B; You, Jianxin

    2016-02-01

    Merkel cell polyomavirus (MCPyV) plays an important role in Merkel cell carcinoma (MCC). MCPyV small T (sT) antigen has emerged as the key oncogenic driver in MCC carcinogenesis. It has also been shown to promote MCPyV LT-mediated replication by stabilizing LT. The importance of MCPyV sT led us to investigate sT functions and to identify potential ways to target this protein. We discovered that MCPyV sT purified from bacteria contains iron-sulfur (Fe/S) clusters. Electron paramagnetic resonance analysis showed that MCPyV sT coordinates a [2Fe-2S] and a [4Fe-4S] cluster. We also observed phenotypic conservation of Fe/S coordination in the sTs of other polyomaviruses. Since Fe/S clusters are critical cofactors in many nucleic acid processing enzymes involved in DNA unwinding and polymerization, our results suggested the hypothesis that MCPyV sT might be directly involved in viral replication. Indeed, we demonstrated that MCPyV sT enhances LT-mediated replication in a manner that is independent of its previously reported ability to stabilize LT. MCPyV sT translocates to nuclear foci containing actively replicating viral DNA, supporting a direct role for sT in promoting viral replication. Mutations of Fe/S cluster-coordinating cysteines in MCPyV sT abolish its ability to stimulate viral replication. Moreover, treatment with cidofovir, a potent antiviral agent, robustly inhibits the sT-mediated enhancement of MCPyV replication but has little effect on the basal viral replication driven by LT alone. This finding further indicates that MCPyV sT plays a direct role in stimulating viral DNA replication and introduces cidofovir as a possible drug for controlling MCPyV infection. MCPyV is associated with a highly aggressive form of skin cancer in humans. Epidemiological surveys for MCPyV seropositivity and sequencing analyses of healthy human skin suggest that MCPyV may represent a common component of the human skin microbial flora. However, much of the biology of the virus

  7. Lipid droplet-binding protein TIP47 regulates hepatitis C Virus RNA replication through interaction with the viral NS5A protein.

    Directory of Open Access Journals (Sweden)

    Dorothee A Vogt

    Full Text Available The nonstructural protein NS5A has emerged as a new drug target in antiviral therapies for Hepatitis C Virus (HCV infection. NS5A is critically involved in viral RNA replication that takes place at newly formed membranes within the endoplasmic reticulum (membranous web and assists viral assembly in the close vicinity of lipid droplets (LDs. To identify host proteins that interact with NS5A, we performed a yeast two-hybrid screen with the N-terminus of NS5A (amino acids 1-31, a well-studied α-helical domain important for the membrane tethering of NS5A. Our studies identified the LD-associated host protein, Tail-Interacting Protein 47 (TIP47 as a novel NS5A interaction partner. Coimmunoprecipitation experiments in Huh7 hepatoma cells confirmed the interaction of TIP47 with full-length NS5A. shRNA-mediated knockdown of TIP47 caused a more than 10-fold decrease in the propagation of full-length infectious HCV in Huh7.5 hepatoma cells. A similar reduction was observed when TIP47 was knocked down in cells harboring an autonomously replicating HCV RNA (subgenomic replicon, indicating that TIP47 is required for efficient HCV RNA replication. A single point mutation (W9A in NS5A that disrupts the interaction with TIP47 but preserves proper subcellular localization severely decreased HCV RNA replication. In biochemical membrane flotation assays, TIP47 cofractionated with HCV NS3, NS5A, NS5B proteins, and viral RNA, and together with nonstructural viral proteins was uniquely distributed to lower-density LD-rich membrane fractions in cells actively replicating HCV RNA. Collectively, our data support a model where TIP47--via its interaction with NS5A--serves as a novel cofactor for HCV infection possibly by integrating LD membranes into the membranous web.

  8. Influenza A virus encoding secreted Gaussia luciferase as useful tool to analyze viral replication and its inhibition by antiviral compounds and cellular proteins.

    Directory of Open Access Journals (Sweden)

    Nadine Eckert

    Full Text Available Reporter genes inserted into viral genomes enable the easy and rapid quantification of virus replication, which is instrumental to efficient in vitro screening of antiviral compounds or in vivo analysis of viral spread and pathogenesis. Based on a published design, we have generated several replication competent influenza A viruses carrying either fluorescent proteins or Gaussia luciferase. Reporter activity could be readily quantified in infected cultures, but the virus encoding Gaussia luciferase was more stable than viruses bearing fluorescent proteins and was therefore analyzed in detail. Quantification of Gaussia luciferase activity in the supernatants of infected culture allowed the convenient and highly sensitive detection of viral spread, and enzymatic activity correlated with the number of infectious particles released from infected cells. Furthermore, the Gaussia luciferase encoding virus allowed the sensitive quantification of the antiviral activity of the neuraminidase inhibitor (NAI zanamivir and the host cell interferon-inducible transmembrane (IFITM proteins 1-3, which are known to inhibit influenza virus entry. Finally, the virus was used to demonstrate that influenza A virus infection is sensitive to a modulator of endosomal cholesterol, in keeping with the concept that IFITMs inhibit viral entry by altering cholesterol levels in the endosomal membrane. In sum, we report the characterization of a novel influenza A reporter virus, which allows fast and sensitive detection of viral spread and its inhibition, and we show that influenza A virus entry is sensitive to alterations of endosomal cholesterol levels.

  9. RECQL5 Suppresses Oncogenic JAK2-Induced Replication Stress and Genomic Instability

    Directory of Open Access Journals (Sweden)

    Edwin Chen

    2015-12-01

    Full Text Available JAK2V617F is the most common oncogenic lesion in patients with myeloproliferative neoplasms (MPNs. Despite the ability of JAK2V617F to instigate DNA damage in vitro, MPNs are nevertheless characterized by genomic stability. In this study, we address this paradox by identifying the DNA helicase RECQL5 as a suppressor of genomic instability in MPNs. We report increased RECQL5 expression in JAK2V617F-expressing cells and demonstrate that RECQL5 is required to counteract JAK2V617F-induced replication stress. Moreover, RECQL5 depletion sensitizes JAK2V617F mutant cells to hydroxyurea (HU, a pharmacological inducer of replication stress and the most common treatment for MPNs. Using single-fiber chromosome combing, we show that RECQL5 depletion in JAK2V617F mutant cells impairs replication dynamics following HU treatment, resulting in increased double-stranded breaks and apoptosis. Cumulatively, these findings identify RECQL5 as a critical regulator of genome stability in MPNs and demonstrate that replication stress-associated cytotoxicity can be amplified specifically in JAK2V617F mutant cells through RECQL5-targeted synthetic lethality.

  10. RECQL5 Suppresses Oncogenic JAK2-Induced Replication Stress and Genomic Instability.

    Science.gov (United States)

    Chen, Edwin; Ahn, Jong Sook; Sykes, David B; Breyfogle, Lawrence J; Godfrey, Anna L; Nangalia, Jyoti; Ko, Amy; DeAngelo, Daniel J; Green, Anthony R; Mullally, Ann

    2015-12-22

    JAK2V617F is the most common oncogenic lesion in patients with myeloproliferative neoplasms (MPNs). Despite the ability of JAK2V617F to instigate DNA damage in vitro, MPNs are nevertheless characterized by genomic stability. In this study, we address this paradox by identifying the DNA helicase RECQL5 as a suppressor of genomic instability in MPNs. We report increased RECQL5 expression in JAK2V617F-expressing cells and demonstrate that RECQL5 is required to counteract JAK2V617F-induced replication stress. Moreover, RECQL5 depletion sensitizes JAK2V617F mutant cells to hydroxyurea (HU), a pharmacological inducer of replication stress and the most common treatment for MPNs. Using single-fiber chromosome combing, we show that RECQL5 depletion in JAK2V617F mutant cells impairs replication dynamics following HU treatment, resulting in increased double-stranded breaks and apoptosis. Cumulatively, these findings identify RECQL5 as a critical regulator of genome stability in MPNs and demonstrate that replication stress-associated cytotoxicity can be amplified specifically in JAK2V617F mutant cells through RECQL5-targeted synthetic lethality. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Early viral replication and induced or constitutive immunity in rainbow trout families with differential resistance to Infectious hematopoietic necrosis virus (IHNV)

    Science.gov (United States)

    Purcell, M.K.; LaPatra, S.E.; Woodson, J.C.; Kurath, G.; Winton, J.R.

    2010-01-01

    The main objective of this study was to assess correlates of innate resistance in rainbow trout full-sibling families that differ in susceptibility to Infectious hematopoietic necrosis virus (IHNV). As part of a commercial breeding program, full-sibling families were challenged with IHNV by waterborne exposure at the 1 g size to determine susceptibility to IHNV. Progeny from select families (N = 7 families) that varied in susceptibility (ranging from 32 to 90% cumulative percent mortality (CPM)) were challenged again at the 10 g size by intra-peritoneal injection and overall mortality, early viral replication and immune responses were evaluated. Mortality challenges included 20–40 fish per family while viral replication and immune response studies included 6 fish per family at each time point (24, 48 and 72 h post-infection (hpi)). CPM at the 1 g size was significantly correlated with CPM at the 10 g size, indicating that inherent resistance was a stable trait irrespective of size. In the larger fish, viral load was measured by quantitative reverse-transcriptase PCR in the anterior kidney and was a significant predictor of family disease outcome at 48 hpi. Type I interferon (IFN) transcript levels were significantly correlated with an individual's viral load at 48 and 72 hpi, while type II IFN gene expression was significantly correlated with an individual's viral load at 24 and 48 hpi. Mean family type I but not type II IFN gene expression was weakly associated with susceptibility at 72 hpi. There was no association between mean family susceptibility and the constitutive expression of a range of innate immune genes (e.g. type I and II IFN pathway genes, cytokine and viral recognition receptor genes). The majority of survivors from the challenge had detectable serum neutralizing antibody titers but no trend was observed among families. This result suggests that even the most resistant families experienced sufficient levels of viral replication to trigger specific

  12. Trends in ART Prescription and Viral Suppression Among HIV-Positive Young Adults in Care in the United States, 2009-2013.

    Science.gov (United States)

    Beer, Linda; Mattson, Christine L; Bradley, Heather; Shouse, Roy L

    2017-09-01

    Only 13% of HIV-positive young adults are estimated to be virally suppressed and, even among those receiving medical care, HIV-positive young adults are less likely than older adults to take antiretroviral therapy (ART), be adherent, and be virally suppressed. We sought to examine trends in treatment and health outcomes from 2009 to 2013 among HIV-positive young adults (aged 18-24 years) in care. The Medical Monitoring Project is a complex sample survey of HIV-infected adults receiving medical care in the United States. We used weighted interview and medical record data collected from June 2009 to May 2014 to estimate trends in the prevalence of ART prescription, adherence, side effects, single-tablet ART regimens, regular care utilization, and viral suppression among young adults. From 2009 to 2013, there were significant increases in ART prescription (76%-87%) and the proportion of young adults taking ART who reported taking single-tablet regimens (49%-62%). There was no significant change in adherence, side effects, or regular care utilization. Although viral suppression at last test did not change (65% at both time periods), the proportion of young adults who were sustainably virally suppressed significantly increased (29%-46%). Accounting for ART prescription and single-tablet regimen use attenuated the sustained viral suppression trend. Although the level of viral suppression among young adults in care remains suboptimal, the observed increases in ART prescription and sustained viral suppression may be a cause for optimism regarding efforts to improve outcomes for this vulnerable population.

  13. Structural equation modelling of viral tropism reveals its impact on achieving viral suppression within 6 months in treatment-naive HIV-1-infected patients after combination antiretroviral therapy.

    Science.gov (United States)

    Mengoli, Carlo; Andreis, Samantha; Scaggiante, Renzo; Cruciani, Mario; Bosco, Oliviero; Ferretto, Roberto; Leoni, Davide; Maffongelli, Gaetano; Basso, Monica; Torti, Carlo; Sarmati, Loredana; Andreoni, Massimo; Palù, Giorgio; Parisi, Saverio Giuseppe

    2017-01-01

    To evaluate the role of pre-treatment co-receptor tropism of plasma HIV on the achievement of viral suppression (plasma HIV RNA 1.69 log 10 copies/mL) at the sixth month of combination antiretroviral therapy (cART) in a cohort of naive patients using, for the first time in this context, a path analysis (PA) approach. Adult patients with chronic infection by subtype B HIV-1 were consecutively enrolled from the start of first-line cART (T0). Genotypic analysis of viral tropism was performed on plasma and interpreted using the bioinformatic tool Geno2pheno, with a false positive rate of 10%. A Bayesian network starting from the viro-immunological data at T0 and at the sixth month of treatment (T1) was set up and this model was evaluated using a PA approach. A total of 262 patients (22.1% bearing an X4 virus) were included; 178 subjects (67.9%) achieved viral suppression. A significant positive indirect effect of bearing X4 virus in plasma at T0 on log 10 HIV RNA at T1 was detected (P = 0.009), the magnitude of this effect was, however, over 10-fold lower than the direct effect of log 10 HIV RNA at T0 on log 10 HIV RNA at T1 (P = 0.000). Moreover, a significant positive indirect effect of bearing an X4 virus on log 10 HIV RNA at T0 (P = 0.003) was apparent. PA overcame the limitations implicit in common multiple regression analysis and showed the possible role of pre-treatment viral tropism at the recommended threshold on the outcome of plasma viraemia in naive patients after 6 months of therapy. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. Discordant Impact of HLA on Viral Replicative Capacity and Disease Progression in Pediatric and Adult HIV Infection.

    Directory of Open Access Journals (Sweden)

    Emily Adland

    2015-06-01

    Full Text Available HLA class I polymorphism has a major influence on adult HIV disease progression. An important mechanism mediating this effect is the impact on viral replicative capacity (VRC of the escape mutations selected in response to HLA-restricted CD8+ T-cell responses. Factors that contribute to slow progression in pediatric HIV infection are less well understood. We here investigate the relationship between VRC and disease progression in pediatric infection, and the effect of HLA on VRC and on disease outcome in adult and pediatric infection. Studying a South African cohort of >350 ART-naïve, HIV-infected children and their mothers, we first observed that pediatric disease progression is significantly correlated with VRC. As expected, VRCs in mother-child pairs were strongly correlated (p = 0.004. The impact of the protective HLA alleles, HLA-B*57, HLA-B*58:01 and HLA-B*81:01, resulted in significantly lower VRCs in adults (p<0.0001, but not in children. Similarly, in adults, but not in children, VRCs were significantly higher in subjects expressing the disease-susceptible alleles HLA-B*18:01/45:01/58:02 (p = 0.007. Irrespective of the subject, VRCs were strongly correlated with the number of Gag CD8+ T-cell escape mutants driven by HLA-B*57/58:01/81:01 present in each virus (p = 0.0002. In contrast to the impact of VRC common to progression in adults and children, the HLA effects on disease outcome, that are substantial in adults, are small and statistically insignificant in infected children. These data further highlight the important role that VRC plays both in adult and pediatric progression, and demonstrate that HLA-independent factors, yet to be fully defined, are predominantly responsible for pediatric non-progression.

  15. Identification of diverse defense mechanisms in trout red blood cells in response to VHSV halted viral replication.

    Science.gov (United States)

    Nombela, Ivan; Puente-Marin, Sara; Chico, Veronica; Villena, Alberto J; Carracedo, Begoña; Ciordia, Sergio; Mena, Maria Carmen; Mercado, Luis; Perez, Luis; Coll, Julio; Estepa, Amparo; Ortega-Villaizan, Maria Del Mar

    2017-01-01

    Background: It has been described that fish nucleated red blood cells (RBCs) generate a wide variety of immune-related gene transcripts when viruses highly replicate inside them and are their main target cell. The immune response and mechanisms of fish RBCs against viruses targeting other cells or tissues has not yet been explored and is the objective of our study. Methods: Trout RBCs were obtained from peripheral blood, ficoll purified and exposed to Viral Haemorrhagic Septicaemia virus (VHSV). Immune response was evaluated by means of RT-qPCR, flow cytometry, immunofluorescence and isobaric tag for relative and absolute quantification (iTRAQ) protein profiling Results: VHSV N gene transcripts incremented early postexposure and were drastically decreased after 6 hours postexposure (hpe). The expression of the type I interferon ( ifn1 ) gene was significantly downregulated at early postexposure (3 hpe), together with a gradual downregulation of interferon-inducible mx and pkr genes until 72 hpe. Type I IFN protein was downregulated and interferon-inducible Mx protein was maintained at basal levels. Co-culture assays of RBCs with TSS (stromal cell line from spleen) revealed the IFN crosstalk between both cell types. On the other hand, anti-microbial peptide β-defensin 1 and neutrophil chemotactic factor interleukin 8 were slightly upregulated in VHSV-exposed RBCs Isobaric tag for relative and absolute quantification (iTRAQ) revealed that VHSV exposure can induce a global protein downregulation in trout RBCs, mainly related to RNA stability and proteasome pathways. The antioxidant/antiviral response is also suggested to be involved in the response of trout RBCs to VHSV. Conclusions: A variety of mechanisms are proposed to be implicated in the antiviral response of trout RBCs against VHSV halted infection. Ongoing research is focused on understanding the mechanisms in detail. To our knowledge, this is the first report that implicates fish RBCs in the antiviral

  16. Metabolic abnormalities and viral replication are associated with biomarkers of vascular dysfunction in HIV-infected children.

    Science.gov (United States)

    Miller, T I; Borkowsky, W; DiMeglio, L A; Dooley, L; Geffner, M E; Hazra, R; McFarland, E J; Mendez, A J; Patel, K; Siberry, G K; Van Dyke, R B; Worrell, C J; Jacobson, D L; Shearer, William; Cooper, Norma; Harris, Lynette; Purswani, Murli; Baig, Mahboobullah; Cintron, Anna; Puga, Ana; Navarro, Sandra; Patton, Doyle; Burchett, Sandra; Karthas, Nancy; Kammerer, Betsy; Yogev, Ram; Malee, Kathleen; Hunter, Scott; Cagwin, Eric; Wiznia, Andrew; Burey, Marlene; Nozyce, Molly; Chen, Janet; Gobs, Elizabeth; Grant, Mitzie; Knapp, Katherine; Allison, Kim; Garvie, Patricia; Acevedo-Flores, Midnela; Rios, Heida; Olivera, Vivian; Silio, Margarita; Borne, Cheryl; Sirois, Patricia; Spector, Stephen; Norris, Kim; Nichols, Sharon; McFarland, Elizabeth; Barr, Emily; Chambers, Carrie; Watson, Douglas; Messenger, Nicole; Belanger, Rose; Dieudonne, Arry; Bettica, Linda; Adubato, Susan; Scott, Gwendolyn; Himic, Lisa; Willen, Elizabeth

    2012-05-01

    HIV-infected children may be at risk for premature cardiovascular disease. We compared levels of biomarkers of vascular dysfunction in HIV-infected children (with and without hyperlipidaemia) with those in HIV-exposed, uninfected (HEU) children enrolled in the Pediatric HIV/AIDS Cohort Study (PHACS), and determined factors associated with these biomarkers. A prospective cohort study was carried out. Biomarkers of inflammation [C-reactive protein (CRP), interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP1)], coagulant dysfunction (fibrinogen and P-selectin), endothelial dysfunction [soluble intracellular cell adhesion molecule-1 (sICAM), soluble vascular cell adhesion molecule-1 (sVCAM) and E-selectin], and metabolic dysfunction (adiponectin) were measured in 226 HIV-infected and 140 HEU children. Anthropometry, body composition, lipids, glucose, insulin, HIV disease severity, and antiretroviral therapy were recorded. The median ages of the children were 12.3 years in the HIV-infected group and 10.1 years in the HEU group. Body mass index (BMI) z-scores, waist and hip circumferences, and percentage body fat were lower in the HIV-infected children. Total and non-high-density lipoprotein (HDL) cholesterol and triglycerides were higher in HIV-infected children. HIV-infected children also had higher MCP-1, fibrinogen, sICAM and sVCAM levels. In multivariable analyses in the HIV-infected children alone, BMI z-score was associated with higher CRP and fibrinogen, but lower MCP-1 and sVCAM. Unfavourable lipid profiles were positively associated with IL-6, MCP-1, fibrinogen, and P- and E-selectin, whereas increased HIV viral load was associated with markers of inflammation (MCP-1 and CRP) and endothelial dysfunction (sICAM and sVCAM). HIV-infected children have higher levels of biomarkers of vascular dysfunction than do HEU children. Risk factors associated with higher biomarkers include unfavourable lipid levels and active HIV replication. © 2011 British HIV

  17. DNA-Binding Properties of African Swine Fever Virus pA104R, a Histone-Like Protein Involved in Viral Replication and Transcription.

    Science.gov (United States)

    Frouco, Gonçalo; Freitas, Ferdinando B; Coelho, João; Leitão, Alexandre; Martins, Carlos; Ferreira, Fernando

    2017-06-15

    African swine fever virus (ASFV) codes for a putative histone-like protein (pA104R) with extensive sequence homology to bacterial proteins that are implicated in genome replication and packaging. Functional characterization of purified recombinant pA104R revealed that it binds to single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) over a wide range of temperatures, pH values, and salt concentrations and in an ATP-independent manner, with an estimated binding site size of about 14 to 16 nucleotides. Using site-directed mutagenesis, the arginine located in pA104R's DNA-binding domain, at position 69, was found to be relevant for efficient DNA-binding activity. Together, pA104R and ASFV topoisomerase II (pP1192R) display DNA-supercoiling activity, although none of the proteins by themselves do, indicating that the two cooperate in this process. In ASFV-infected cells, A104R transcripts were detected from 2 h postinfection (hpi) onward, reaching a maximum concentration around 16 hpi. pA104R was detected from 12 hpi onward, localizing with viral DNA replication sites and being found exclusively in the Triton-insoluble fraction. Small interfering RNA (siRNA) knockdown experiments revealed that pA104R plays a critical role in viral DNA replication and gene expression, with transfected cells showing lower viral progeny numbers (up to a reduction of 82.0%), lower copy numbers of viral genomes (-78.3%), and reduced transcription of a late viral gene (-47.6%). Taken together, our results strongly suggest that pA104R participates in the modulation of viral DNA topology, probably being involved in viral DNA replication, transcription, and packaging, emphasizing that ASFV mutants lacking the A104R gene could be used as a strategy to develop a vaccine against ASFV. IMPORTANCE Recently reintroduced in Europe, African swine fever virus (ASFV) causes a fatal disease in domestic pigs, causing high economic losses in affected countries, as no vaccine or treatment is currently

  18. Construction of a subgenomic CV-B3 replicon expressing emerald green fluorescent protein to assess viral replication of a cardiotropic enterovirus strain in cultured human cells.

    Science.gov (United States)

    Wehbe, Michel; Huguenin, Antoine; Leveque, Nicolas; Semler, Bert L; Hamze, Monzer; Andreoletti, Laurent; Bouin, Alexis

    2016-04-01

    Coxsackieviruses B (CV-B) (Picornaviridae) are a common infectious cause of acute myocarditis in children and young adults, a disease, which is a precursor to 10-20% of chronic myocarditis and dilated cardiomyopathy (DCM) cases. The mechanisms involved in the disease progression from acute to chronic myocarditis phase and toward the DCM clinical stage are not fully understood but are influenced by both viral and host factors. Subgenomic replicons of CV-B can be used to assess viral replication mechanisms in human cardiac cells and evaluate the effects of potential antiviral drugs on viral replication activities. Our objectives were to generate a reporter replicon from a cardiotropic prototype CV-B3/28 strain and to characterize its replication properties into human cardiac primary cells. To obtain this replicon, a cDNA plasmid containing the full CV-B3/28 genome flanked by a hammerhead ribozyme sequence and an MluI restriction site was generated and used as a platform for the insertion of sequences encoding emerald green fluorescent protein (EmGFP) in place of those encoding VP3. In vitro transcribed RNA from this plasmid was transfected into HeLa cells and human primary cardiac cells and was able to produce EmGFP and VP1-containing polypeptides. Moreover, non-structural protein biological activity was assessed by the specific cleavage of eIF4G1 by viral 2A(pro). Viral RNA replication was indirectly demonstrated by inhibition assays, fluoxetine was added to cell culture and prevented the EmGFP synthesis. Our results indicated that the EmGFP CV-B3 replicon was able to replicate and translate as well as the CV-B3/28 prototype strain. Our EmGFP CV-B3 replicon will be a valuable tool to readily investigate CV-B3 replication activities in human target cell models. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Mutations in the C3 region of human and simian immunodeficiency virus envelope have differential effects on viral infectivity, replication, and CD4-dependency

    International Nuclear Information System (INIS)

    Otto, Claas; Puffer, Bridget A.; Poehlmann, Stefan; Doms, Robert W.; Kirchhoff, Frank

    2003-01-01

    Residues within the highly conserved C3 region of human and simian immunodeficiency virus (HIV, SIV) envelope proteins (Envs) bind directly to the cellular CD4 receptor. However, substitutions of D385, which is critical for CD4 engagement along with other changes such as G382R, G383R, frequently arise in SIV mac-infected macaques. We investigated the influence of substitutions in the SIVmac and HIV-1 C3 regions on viral entry, dependence on CD4, and replication. Mutations flanking the C3 region such as G382R or V388A enhanced and changes within the C3 region (i.e., G383R or D385N) impaired SIVmac infectivity. Several naturally occurring sequence variations in the SIVmac Env C3 region facilitated CD4-independent membrane fusion but abrogated viral replication, suggesting that efficient infection requires additional changes elsewhere in Env. Substitutions of S365R and D368G in the HIV-1 Env, which correspond to G382 and D385 in SIVmac Env, consistently impaired viral infectivity. In contrast, mutation of D368N resulted in a virus that could not spread in cells expressing low levels of CD4, but which replicated efficiently when high levels of CD4 were expressed. Thus, changes in the C3 region of HIV-1 or SIVmac Env can have differential effects on viral infectivity and CD4-dependency. We conclude that substitutions flanking the C3 region in SIVmac Env such as G382R or V388A represent one step toward adaptation to growth in target cells expressing low CD4 levels, whereas changes within the C3 region that disrupt CD4 binding might indicate the emergence of CD4-independent variants at later stages of infection, which could potentially broaden viral tropism

  20. Retention on buprenorphine is associated with high levels of maximal viral suppression among HIV-infected opioid dependent released prisoners.

    Directory of Open Access Journals (Sweden)

    Sandra A Springer

    Full Text Available HIV-infected prisoners lose viral suppression within the 12 weeks after release to the community. This prospective study evaluates the use of buprenorphine/naloxone (BPN/NLX as a method to reduce relapse to opioid use and sustain viral suppression among released HIV-infected prisoners meeting criteria for opioid dependence (OD.From 2005-2010, 94 subjects meeting DSM-IV criteria for OD were recruited from a 24-week prospective trial of directly administered antiretroviral therapy (DAART for released HIV-infected prisoners; 50 (53% selected BPN/NLX and were eligible to receive it for 6 months; the remaining 44 (47% selected no BPN/NLX therapy. Maximum viral suppression (MVS, defined as HIV-1 RNA<50 copies/mL, was compared for the BPN/NLX and non-BPN/NLX (N = 44 groups.The two groups were similar, except the BPN/NLX group was significantly more likely to be Hispanic (56.0% v 20.4%, from Hartford (74.4% v 47.7% and have higher mean global health quality of life indicator scores (54.18 v 51.40. MVS after 24 weeks of being released was statistically correlated with 24-week retention on BPN/NLX [AOR = 5.37 (1.15, 25.1], having MVS at the time of prison-release [AOR = 10.5 (3.21, 34.1] and negatively with being Black [AOR = 0.13 (0.03, 0.68]. Receiving DAART or methadone did not correlate with MVS.In recognition that OD is a chronic relapsing disease, strategies that initiate and retain HIV-infected prisoners with OD on BPN/NLX is an important strategy for improving HIV treatment outcomes as a community transition strategy.

  1. History of viral suppression on combination antiretroviral therapy as a predictor of virological failure after a treatment change

    DEFF Research Database (Denmark)

    Reekie, J; Mocroft, A; Ledergerber, B

    2010-01-01

    . METHODS: A total of 1827 patients on cART starting at least one new antiretroviral from 1 January 2000 while maintaining a suppressed viral load were included in the analysis. Poisson regression analysis identified factors predictive of virological failure after baseline in addition to traditional...... demographic variables. Baseline was defined as the date of starting new antiretrovirals. RESULTS: Four hundred and fifty-one patients (24.7%) experienced virological failure, with an incidence rate (IR) of 7.3 per 100 person-years of follow-up (PYFU) [95% confidence interval (CI) 6.7-8.0]. After adjustment...

  2. Viral Polymerases

    Science.gov (United States)

    Choi, Kyung H.

    2016-01-01

    Viral polymerases play a central role in viral genome replication and transcription. Based on the genome type and the specific needs of particular virus, RNA-dependent RNA polymerase, RNA-dependent DNA polymerase, DNA-dependent RNA polymerase, and DNA-dependent RNA polymerases are found in various viruses. Viral polymerases are generally active as a single protein capable of carrying out multiple functions related to viral genome synthesis. Specifically, viral polymerases use variety of mechanisms to recognize initial binding sites, ensure processive elongation, terminate replication at the end of the genome, and also coordinate the chemical steps of nucleic acid synthesis with other enzymatic activities. This review focuses on different viral genome replication and transcription strategies, and the polymerase interactions with various viral proteins that are necessary to complete genome synthesis. PMID:22297518

  3. Human parvovirus B19 infection causes cell cycle arrest of human erythroid progenitors at late S phase that favors viral DNA replication.

    Science.gov (United States)

    Luo, Yong; Kleiboeker, Steve; Deng, Xuefeng; Qiu, Jianming

    2013-12-01

    Human parvovirus B19 (B19V) infection has a unique tropism to human erythroid progenitor cells (EPCs) in human bone marrow and the fetal liver. It has been reported that both B19V infection and expression of the large nonstructural protein NS1 arrested EPCs at a cell cycle status with a 4 N DNA content, which was previously claimed to be "G2/M arrest." However, a B19V mutant infectious DNA (M20(mTAD2)) replicated well in B19V-semipermissive UT7/Epo-S1 cells but did not induce G2/M arrest (S. Lou, Y. Luo, F. Cheng, Q. Huang, W. Shen, S. Kleiboeker, J. F. Tisdale, Z. Liu, and J. Qiu, J. Virol. 86:10748-10758, 2012). To further characterize cell cycle arrest during B19V infection of EPCs, we analyzed the cell cycle change using 5-bromo-2'-deoxyuridine (BrdU) pulse-labeling and DAPI (4',6-diamidino-2-phenylindole) staining, which precisely establishes the cell cycle pattern based on both cellular DNA replication and nuclear DNA content. We found that although both B19V NS1 transduction and infection immediately arrested cells at a status of 4 N DNA content, B19V-infected 4 N cells still incorporated BrdU, indicating active DNA synthesis. Notably, the BrdU incorporation was caused neither by viral DNA replication nor by cellular DNA repair that could be initiated by B19V infection-induced cellular DNA damage. Moreover, several S phase regulators were abundantly expressed and colocalized within the B19V replication centers. More importantly, replication of the B19V wild-type infectious DNA, as well as the M20(mTAD2) mutant, arrested cells at S phase. Taken together, our results confirmed that B19V infection triggers late S phase arrest, which presumably provides cellular S phase factors for viral DNA replication.

  4. A simple self-reported adherence tool as a predictor of viral rebound in people with viral suppression on antiretroviral therapy.

    Science.gov (United States)

    O'Connor, J L; Gardner, E M; Esser, S; Mannheimer, S B; Lifson, A R; Telzak, E E; Phillips, A N

    2016-02-01

    The aim of the study was to investigate the relationship between self-reported antiretroviral therapy (ART) adherence and virological outcomes in the multinational Strategies for Management of Antiretroviral Therapy (SMART) study. Eligible participants were from the continuous ART arm and had at least one viral load (VL) ≤ 50 HIV-1 RNA copies/mL and a subsequent VL value (VL pair). Self-reported adherence was measured at each visit using a five-point Likert scale which employed a 7-day recall. High adherence was defined as taking 'all pills every day' (level 1) for every regimen component; all others had suboptimal adherence (levels 2 - 5). In individuals with VL suppression (≤ 50 copies/mL), the association between adherence (at the time of VL suppression) and VL rebound (> 200 copies/mL at next visit) was assessed using multivariable logistic regression with generalized estimating equations. A total of 10 761 sets of VL pairs from 1986 participants were included in the study. For 1220 (11%) VL pairs, adherence was suboptimal. For 507 VL pairs (5%), VL rebound occurred. The risk of rebound generally increased as adherence decreased: 4.2% for level 1, 7.7% for level 2, 16.3% for level 3, 9.4% for level 4 and 12.9% for level 5. In multivariable analysis, suboptimal adherence at the time of suppression was associated with a 50% increased odds of experiencing subsequent VL rebound [odds ratio (OR) 1.51; 95% confidence interval (CI) 1.19-1.92; P = 0.0023], compared with high adherence. Self-reported suboptimal adherence in people with VL suppression is associated with an increased risk of VL rebound. Our findings highlight the importance of continued adherence counselling, even in people with VL suppression, and to ensure that people with HIV infection maintain excellent adherence in order to minimize the risk of VL rebound. © 2015 British HIV Association.

  5. Effective suppression of Dengue fever virus in mosquito cell cultures using retroviral transduction of hammerhead ribozymes targeting the viral genome

    Directory of Open Access Journals (Sweden)

    Mohammed Ahmed

    2009-06-01

    Full Text Available Abstract Outbreaks of Dengue impose a heavy economic burden on developing countries in terms of vector control and human morbidity. Effective vaccines against all four serotypes of Dengue are in development, but population replacement with transgenic vectors unable to transmit the virus might ultimately prove to be an effective approach to disease suppression, or even eradication. A key element of the refractory transgenic vector approach is the development of transgenes that effectively prohibit viral transmission. In this report we test the effectiveness of several hammerhead ribozymes for suppressing DENV in lentivirus-transduced mosquito cells in an attempt to mimic the transgenic use of these effector molecules in mosquitoes. A lentivirus vector that expresses these ribozymes as a fusion RNA molecule using an Ae. aegypti tRNAval promoter and terminating with a 60A tail insures optimal expression, localization, and activity of the hammerhead ribozyme against the DENV genome. Among the 14 hammerhead ribozymes we designed to attack the DENV-2 NGC genome, several appear to be relatively effective in reducing virus production from transduced cells by as much as 2 logs. Among the sequences targeted are 10 that are conserved among all DENV serotype 2 strains. Our results confirm that hammerhead ribozymes can be effective in suppressing DENV in a transgenic approach, and provide an alternative or supplementary approach to proposed siRNA strategies for DENV suppression in transgenic mosquitoes.

  6. Modulation of HIV-1 Gag NC/p1 cleavage efficiency affects protease inhibitor resistance and viral replicative capacity

    Directory of Open Access Journals (Sweden)

    van Maarseveen Noortje M

    2012-04-01

    Full Text Available Abstract Background Mutations in the substrate of HIV-1 protease, especially changes in the NC/p1 cleavage site, can directly contribute to protease inhibitor (PI resistance and also compensate for defects in viral replicative capacity (RC due to a drug resistant protease. These NC/p1 changes are known to enhance processing of the Gag protein. To investigate the capacity of HIV-1 to modulate Gag cleavage and its consequences for PI resistance and RC, we performed a detailed enzymatic and virological analysis using a set of PI resistant NC/p1 variants (HXB2431V, HXB2436E+437T, HXB2437T and HXB2437V. Results Here, we demonstrate that single NC/p1 mutants, which displayed only a slight increase in PI resistance did not show an obvious change in RC. In contrast, the double NC/p1 mutant, which displayed a clear increase in processing efficiency and PI resistance, demonstrated a clear reduction in RC. Cleavage analysis showed that a tridecameric NC/p1 peptide representing the double NC/p1 mutant was cleaved in two specific ways instead of one. The observed decrease in RC for the double NC/p1 mutant (HXB2436E+437T could (partially be restored by either reversion of the 436E change or by acquisition of additional changes in the NC/p1 cleavage site at codon 435 or 438 as was revealed during in vitro evolution experiments. These changes not only restored RC but also reduced PI resistance levels. Furthermore these changes normalized Gag processing efficiency and obstructed the novel secondary cleavage site observed for the double NC/p1 mutant. Conclusions The results of this study clearly demonstrate that HIV-1 can modulate Gag processing and thereby PI resistance. Distinct increases in Gag cleavage and PI resistance result in a reduced RC that can only be restored by amino acid changes in NC/p1 which reduce Gag processing to an optimal rate.

  7. A single social defeat transiently suppresses the anti-viral immune response in mice

    NARCIS (Netherlands)

    de Groot, Johanna; Milligen, Florine J. van; Moonen-Leusen, Bernie W.M.; Thomas, Gethin; Koolhaas, Jaap M.

    1999-01-01

    Most of the studies dealing with effects of stress on anti-viral immunity have been carried out with stressors that are of long duration and that bear little relationship to the nature of the species. In this paper, we investigated the effect of a stressor mimicking real-life situations more

  8. Suppression of HIV-1 viral load after multiple changes in high active ...

    African Journals Online (AJOL)

    1-infected patients. However, the virus persists ... chronological changes in HIV viral load and CD4+ T-cell count, and treatment outcomes of multiple combinations of .... Lewin SR, Rouzioux C. HIV cure and eradication: how will we get from the ...

  9. Effects of mutations within the SV40 large T antigen ATPase/p53 binding domain on viral replication and transformation.

    Science.gov (United States)

    Peden, K W; Srinivasan, A; Vartikar, J V; Pipas, J M

    1998-01-01

    The simian virus 40 (SV40) large T antigen is a 708 amino-acid protein possessing multiple biochemical activities that play distinct roles in productive infection or virus-induced cell transformation. The carboxy-terminal portion of T antigen includes a domain that carries the nucleotide binding and ATPase activities of the protein, as well as sequences required for T antigen to associate with the cellular tumor suppressor p53. Consequently this domain functions both in viral DNA replication and cellular transformation. We have generated a collection of SV40 mutants with amino-acid deletions, insertions or substitutions in specific domains of the protein. Here we report the properties of nine mutants with single or multiple substitutions between amino acids 402 and 430, a region thought to be important for both the p53 binding and ATPase functions. The mutants were examined for the ability to produce infectious progeny virions, replicate viral DNA in vivo, perform in trans complementation tests, and transform established cell lines. Two of the mutants exhibited a wild-type phenotype in all these tests. The remaining seven mutants were defective for plaque formation and viral DNA replication, but in each case these defects could be complemented by a wild-type T antigen supplied in trans. One of these replication-defective mutants efficiently transformed the REF52 and C3H10T1/2 cell lines as assessed by the dense-focus assay. The remaining six mutants were defective for transforming REF52 cells and transformed the C3H10T1/2 line with a reduced efficiency. The ability of mutant T antigen to transform REF52 cells correlated with their ability to induce increased levels of p53.

  10. Structural Determinants of Antiretroviral Therapy Use, HIV Care Attendance, and Viral Suppression among Adolescents and Young Adults Living with HIV.

    Science.gov (United States)

    Kahana, Shoshana Y; Jenkins, Richard A; Bruce, Douglas; Fernandez, Maria I; Hightow-Weidman, Lisa B; Bauermeister, Jose A

    2016-01-01

    The authors examined associations between structural characteristics and HIV disease management among a geographically diverse sample of behaviorally and perinatally HIV-infected adolescents and young adults in the United States. The sample included 1891 adolescents and young adults living with HIV (27.8% perinatally infected; 72.2% behaviorally infected) who were linked to care through 20 Adolescent Medicine Trials Network for HIV/AIDS Interventions Units. All completed audio computer-assisted self-interview surveys. Chart abstraction or blood draw provided viral load data. Geographic-level variables were extracted from the United States Census Bureau (e.g., socioeconomic disadvantage, percent of Black and Latino households, percent rural) and Esri Crime (e.g., global crime index) databases as Zip Code Tabulation Areas. AIDSVu data (e.g., prevalence of HIV among youth) were extracted at the county-level. Using HLM v.7, the authors conducted means-as-outcomes random effects multi-level models to examine the association between structural-level and individual-level factors and (1) being on antiretroviral therapy (ART) currently; (2) being on ART for at least 6 months; (3) missed HIV care appointments (not having missed any vs. having missed one or more appointments) over the past 12 months; and (4) viral suppression (defined by the corresponding assay cutoff for the lower limit of viral load at each participating site which denoted nondetectability vs. detectability). Frequencies for the 4 primary outcomes were as follows: current ART use (n = 1120, 59.23%); ART use for ≥6 months (n = 861, 45.53%); at least one missed HIV care appointment (n = 936, 49.50); and viral suppression (n = 577, 30.51%). After adjusting for individual-level factors, youth living in more disadvantaged areas (defined by a composite score derived from 2010 Census indicators including percent poverty, percent receiving public assistance, percent of female, single-headed households, percent

  11. Structural Determinants of Antiretroviral Therapy Use, HIV Care Attendance, and Viral Suppression among Adolescents and Young Adults Living with HIV.

    Directory of Open Access Journals (Sweden)

    Shoshana Y Kahana

    Full Text Available The authors examined associations between structural characteristics and HIV disease management among a geographically diverse sample of behaviorally and perinatally HIV-infected adolescents and young adults in the United States.The sample included 1891 adolescents and young adults living with HIV (27.8% perinatally infected; 72.2% behaviorally infected who were linked to care through 20 Adolescent Medicine Trials Network for HIV/AIDS Interventions Units. All completed audio computer-assisted self-interview surveys. Chart abstraction or blood draw provided viral load data. Geographic-level variables were extracted from the United States Census Bureau (e.g., socioeconomic disadvantage, percent of Black and Latino households, percent rural and Esri Crime (e.g., global crime index databases as Zip Code Tabulation Areas. AIDSVu data (e.g., prevalence of HIV among youth were extracted at the county-level. Using HLM v.7, the authors conducted means-as-outcomes random effects multi-level models to examine the association between structural-level and individual-level factors and (1 being on antiretroviral therapy (ART currently; (2 being on ART for at least 6 months; (3 missed HIV care appointments (not having missed any vs. having missed one or more appointments over the past 12 months; and (4 viral suppression (defined by the corresponding assay cutoff for the lower limit of viral load at each participating site which denoted nondetectability vs. detectability.Frequencies for the 4 primary outcomes were as follows: current ART use (n = 1120, 59.23%; ART use for ≥6 months (n = 861, 45.53%; at least one missed HIV care appointment (n = 936, 49.50; and viral suppression (n = 577, 30.51%. After adjusting for individual-level factors, youth living in more disadvantaged areas (defined by a composite score derived from 2010 Census indicators including percent poverty, percent receiving public assistance, percent of female, single-headed households, percent

  12. Structural Determinants of Antiretroviral Therapy Use, HIV Care Attendance, and Viral Suppression among Adolescents and Young Adults Living with HIV

    Science.gov (United States)

    Kahana, Shoshana Y.; Jenkins, Richard A.; Bruce, Douglas; Fernandez, Maria I.; Hightow-Weidman, Lisa B.; Bauermeister, Jose A.

    2016-01-01

    Background The authors examined associations between structural characteristics and HIV disease management among a geographically diverse sample of behaviorally and perinatally HIV-infected adolescents and young adults in the United States. Methods The sample included 1891 adolescents and young adults living with HIV (27.8% perinatally infected; 72.2% behaviorally infected) who were linked to care through 20 Adolescent Medicine Trials Network for HIV/AIDS Interventions Units. All completed audio computer–assisted self-interview surveys. Chart abstraction or blood draw provided viral load data. Geographic-level variables were extracted from the United States Census Bureau (e.g., socioeconomic disadvantage, percent of Black and Latino households, percent rural) and Esri Crime (e.g., global crime index) databases as Zip Code Tabulation Areas. AIDSVu data (e.g., prevalence of HIV among youth) were extracted at the county-level. Using HLM v.7, the authors conducted means-as-outcomes random effects multi-level models to examine the association between structural-level and individual-level factors and (1) being on antiretroviral therapy (ART) currently; (2) being on ART for at least 6 months; (3) missed HIV care appointments (not having missed any vs. having missed one or more appointments) over the past 12 months; and (4) viral suppression (defined by the corresponding assay cutoff for the lower limit of viral load at each participating site which denoted nondetectability vs. detectability). Results Frequencies for the 4 primary outcomes were as follows: current ART use (n = 1120, 59.23%); ART use for ≥6 months (n = 861, 45.53%); at least one missed HIV care appointment (n = 936, 49.50); and viral suppression (n = 577, 30.51%). After adjusting for individual-level factors, youth living in more disadvantaged areas (defined by a composite score derived from 2010 Census indicators including percent poverty, percent receiving public assistance, percent of female, single

  13. Qualitative and quantitative HIV antibodies and viral reservoir size characterization in vertically infected children with virological suppression.

    Science.gov (United States)

    Brice, Josephine; Sylla, Mariam; Sayon, Sophie; Telly, Fatoumata; Bocar-Fofana, Djeneba; Murphy, Robert; Lambert-Niclot, Sidonie; Todesco, Eve; Grude, Maxime; Barin, Francis; Diallo, Souleymane; Pillay, Deenan; Derache, Anne; Calvez, Vincent; Marcelin, Anne-Geneviève; Maiga, Almoustapha Issiaka

    2017-04-01

    Absence of detectable viraemia after treatment cessation in some vertically HIV-infected (VHIV) children suggests that early initiation of HAART could lead to functional cure. We described the factors associated with HIV antibody levels and the viral reservoir size in HAART-treated VHIV children. Study included 97 VHIV children with virological suppression, in Bamako, Mali. The anti-gp41 antibody activities and HIV serostatus were assessed. The viral reservoir size was measured by quantifying total cell-associated HIV DNA. Among the children studied, the median total HIV DNA level was 445 copies/10 6 cells (IQR = 187-914) and the median anti-gp41 antibody activity was 0.29 OD (IQR = 0.18-0.75). Low activity of anti-gp41 antibodies was associated with a younger age of HAART initiation ( P  =   0.01). Overall, eight HIV-1 seroreversions were identified. Study identified potential candidates with low viral reservoir and low antibody levels or activities for future trials aiming to reduce HIV-1 reservoir to limit HAART duration. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  14. Replicative homeostasis II: Influence of polymerase fidelity on RNA virus quasispecies biology: Implications for immune recognition, viral autoimmunity and other "virus receptor" diseases

    Directory of Open Access Journals (Sweden)

    Sallie Richard

    2005-08-01

    Full Text Available Abstract Much of the worlds' population is in active or imminent danger from established infectious pathogens, while sporadic and pandemic infections by these and emerging agents threaten everyone. RNA polymerases (RNApol generate enormous genetic and consequent antigenic heterogeneity permitting both viruses and cellular pathogens to evade host defences. Thus, RNApol causes more morbidity and premature mortality than any other molecule. The extraordinary genetic heterogeneity defining viral quasispecies results from RNApol infidelity causing rapid cumulative genomic RNA mutation a process that, if uncontrolled, would cause catastrophic loss of sequence integrity and inexorable quasispecies extinction. Selective replication and replicative homeostasis, an epicyclical regulatory mechanism dynamically linking RNApol fidelity and processivity with quasispecies phenotypic diversity, modulating polymerase fidelity and, hence, controlling quasispecies behaviour, prevents this happening and also mediates immune escape. Perhaps more importantly, ineluctable generation of broad phenotypic diversity after viral RNA is translated to protein quasispecies suggests a mechanism of disease that specifically targets, and functionally disrupts, the host cell surface molecules – including hormone, lipid, cell signalling or neurotransmitter receptors – that viruses co-opt for cell entry. This mechanism – "Viral Receptor Disease (VRD" – may explain so-called "viral autoimmunity", some classical autoimmune disorders and other diseases, including type II diabetes mellitus, and some forms of obesity. Viral receptor disease is a unifying hypothesis that may also explain some diseases with well-established, but multi-factorial and apparently unrelated aetiologies – like coronary artery and other vascular diseases – in addition to diseases like schizophrenia that are poorly understood and lack plausible, coherent, pathogenic explanations.

  15. Replicative homeostasis II: influence of polymerase fidelity on RNA virus quasispecies biology: implications for immune recognition, viral autoimmunity and other "virus receptor" diseases.

    Science.gov (United States)

    Sallie, Richard

    2005-08-22

    Much of the worlds' population is in active or imminent danger from established infectious pathogens, while sporadic and pandemic infections by these and emerging agents threaten everyone. RNA polymerases (RNApol) generate enormous genetic and consequent antigenic heterogeneity permitting both viruses and cellular pathogens to evade host defences. Thus, RNApol causes more morbidity and premature mortality than any other molecule. The extraordinary genetic heterogeneity defining viral quasispecies results from RNApol infidelity causing rapid cumulative genomic RNA mutation a process that, if uncontrolled, would cause catastrophic loss of sequence integrity and inexorable quasispecies extinction. Selective replication and replicative homeostasis, an epicyclical regulatory mechanism dynamically linking RNApol fidelity and processivity with quasispecies phenotypic diversity, modulating polymerase fidelity and, hence, controlling quasispecies behaviour, prevents this happening and also mediates immune escape. Perhaps more importantly, ineluctable generation of broad phenotypic diversity after viral RNA is translated to protein quasispecies suggests a mechanism of disease that specifically targets, and functionally disrupts, the host cell surface molecules--including hormone, lipid, cell signalling or neurotransmitter receptors--that viruses co-opt for cell entry. This mechanism--"Viral Receptor Disease (VRD)"--may explain so-called "viral autoimmunity", some classical autoimmune disorders and other diseases, including type II diabetes mellitus, and some forms of obesity. Viral receptor disease is a unifying hypothesis that may also explain some diseases with well-established, but multi-factorial and apparently unrelated aetiologies--like coronary artery and other vascular diseases--in addition to diseases like schizophrenia that are poorly understood and lack plausible, coherent, pathogenic explanations.

  16. Trametinib suppresses HIV-1 replication by interfering with the disassembly of human immunodeficiency virus type 1 capsid core.

    Science.gov (United States)

    Dochi, Takeo; Akita, Ayano; Kishimoto, Naoki; Takamune, Nobutoki; Misumi, Shogo

    2018-01-08

    Our previous study showed that the phosphorylation of a highly conserved serine residue, Ser 16 in the human immunodeficiency virus type 1 (HIV-1) capsid (CA) protein is promoted by virion-incorporated extracellular signal-regulated kinase 2 (ERK2) and required for proper peptidyl-prolyl isomerase (Pin1)-mediated uncoating. Interestingly, western blot analysis demonstrated that phosphorylated/activated mitogen-activated protein kinase kinase 1/2 (MEK1/2), the upstream activator of ERK2, as well as ERK2 are incorporated into virions. Here, we show that the MEK1/2 selective allosteric inhibitor Trametinib reduces HIV-1 infectivity via the decrease in virion-incorporated ERK2 phosphorylation. The treatment of chronic HIV-1-infected T-cell line, CEM/LAV-1 cells with Trametinib results in a decrease in ERK2 phosphorylation in the virions. The viruses have relatively low infectivity and impaired reverse transcription. Cell-based fate-of-capsid uncoating assay showed that the reduction in infectivity was caused by a functional impairment of the uncoating process. Furthermore, the viruses from Trametinib-treated CEM/LAV-1 cells also showed decreased reverse transcription efficiency and attenuated multiple rounds of replication in human peripheral blood mononuclear cells (PBMCs). Taken together, these findings suggest that Trametinib suppresses HIV-1 replication by abrogating the proper disassembly of CA core. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. A genetic screen identifies interferon-α effector genes required to suppress hepatitis C virus replication.

    Science.gov (United States)

    Fusco, Dahlene N; Brisac, Cynthia; John, Sinu P; Huang, Yi-Wen; Chin, Christopher R; Xie, Tiao; Zhao, Hong; Jilg, Nikolaus; Zhang, Leiliang; Chevaliez, Stephane; Wambua, Daniel; Lin, Wenyu; Peng, Lee; Chung, Raymond T; Brass, Abraham L

    2013-06-01

    Hepatitis C virus (HCV) infection is a leading cause of end-stage liver disease. Interferon-α (IFNα) is an important component of anti-HCV therapy; it up-regulates transcription of IFN-stimulated genes, many of which have been investigated for their antiviral effects. However, all of the genes required for the antiviral function of IFNα (IFN effector genes [IEGs]) are not known. IEGs include not only IFN-stimulated genes, but other nontranscriptionally induced genes that are required for the antiviral effect of IFNα. In contrast to candidate approaches based on analyses of messenger RNA (mRNA) expression, identification of IEGs requires a broad functional approach. We performed an unbiased genome-wide small interfering RNA screen to identify IEGs that inhibit HCV. Huh7.5.1 hepatoma cells were transfected with small interfering RNAs incubated with IFNα and then infected with JFH1 HCV. Cells were stained using HCV core antibody, imaged, and analyzed to determine the percent infection. Candidate IEGs detected in the screen were validated and analyzed further. The screen identified 120 previously unreported IEGs. From these, we more fully evaluated the following: asparagine-linked glycosylation 10 homolog (yeast, α-1,2-glucosyltransferase); butyrylcholinesterase; dipeptidyl-peptidase 4 (CD26, adenosine deaminase complexing protein 2); glucokinase (hexokinase 4) regulator; guanylate cyclase 1, soluble, β 3; MYST histone acetyltransferase 1; protein phosphatase 3 (formerly 2B), catalytic subunit, β isoform; peroxisomal proliferator-activated receptor-γ-DBD-interacting protein 1; and solute carrier family 27 (fatty acid transporter), member 2; and demonstrated that they enabled IFNα-mediated suppression of HCV at multiple steps of its life cycle. Expression of these genes had more potent effects against flaviviridae because a subset was required for IFNα to suppress dengue virus but not influenza A virus. In addition, many of the host genes detected in this

  18. Silencing of neurotropic flavivirus replication in the central nervous system by combining multiple microRNA target insertions in two distinct viral genome regions

    Science.gov (United States)

    Teterina, Natalya L.; Liu, Guangping; Maximova, Olga A.; Pletnev, Alexander G.

    2014-01-01

    In recent years, microRNA-targeting has become an effective strategy for selective control of tissue-tropism and pathogenesis of both DNA and RNA viruses. Here, using a neurotropic flavivirus as a model, we demonstrate that simultaneous miRNA targeting of the viral genome in the open reading frame and 3′-noncoding regions for brain-expressed miRNAs had an additive effect and produced a more potent attenuation of the virus compared to separate targeting of those regions. Multiple miRNA co-targeting of these two distantly located regions completely abolished the virus neurotropism as no viral replication was detected in the developing brain of neonatal mice. Furthermore, no viral antigens were detected in neurons, and neuronal integrity in the brain of mice was well preserved. This miRNA co-targeting approach can be adapted for other viruses in order to minimize their replication in a cell- or tissue-type specific manner, but most importantly, to prevent virus escape from miRNA-mediated silencing. PMID:24889244

  19. Immune Activation and Viral Replication after Vaccination with an Influenza A H1N1 2009 Vaccine in HIV-Infected Children Receiving Antiretroviral Therapy

    Directory of Open Access Journals (Sweden)

    Nattawat Onlamoon

    2013-01-01

    Full Text Available Immunization with a pandemic influenza A H1N1 2009 was recommended for HIV-infected patients. However, there is limited information concerning the impact of immunization with this vaccine on immune activation and HIV viral replication. In this study, 45 HIV-infected children and adolescents receiving antiretroviral therapy were immunized with a 2-dose series of nonadjuvated monovalent influenza A H1N1 2009 vaccine upon enrollment and approximately 1 month later. Immunogenicity was determined by haemagglutination inhibition assay. The level of immune activation was determined by identification of CD38 and HLA-DR on CD8+ T cells. Patients were divided into 2 groups which include patients who had an undetectable HIV viral load (HIV detectable group and patients who show virological failure (HIV nondetectable group. The results showed seroconversion rate of 55.2% in HIV nondetectable group, whereas 31.3% was found in HIV detectable group. Both groups of patients showed no major increase in immune activation after immunization. Interestingly, a decrease in the frequency of CD8+ T cells that coexpressed CD38 and HLA-DR was observed after immunization in both groups of patients. We suggested that immunization with influenza A H1N1 2009 vaccine can induce immune response to the pandemic virus without major impact on HIV viral replication and immune activation.

  20. The glycoprotein and the matrix protein of rabies virus affect pathogenicity by regulating viral replication and facilitating cell-to-cell spread.

    Science.gov (United States)

    Pulmanausahakul, Rojjanaporn; Li, Jianwei; Schnell, Matthias J; Dietzschold, Bernhard

    2008-03-01

    While the glycoprotein (G) of rabies virus (RV) is known to play a predominant role in the pathogenesis of rabies, the function of the RV matrix protein (M) in RV pathogenicity is not completely clear. To further investigate the roles of these proteins in viral pathogenicity, we constructed chimeric recombinant viruses by exchanging the G and M genes of the attenuated SN strain with those of the highly pathogenic SB strain. Infection of mice with these chimeric viruses revealed a significant increase in the pathogenicity of the SN strain bearing the RV G from the pathogenic SB strain. Moreover, the pathogenicity was further increased when both G and M from SB were introduced into SN. Interestingly, the replacement of the G or M gene or both in SN by the corresponding genes of SB was associated with a significant decrease in the rate of viral replication and viral RNA synthesis. In addition, a chimeric SN virus bearing both the M and G genes from SB exhibited more efficient cell-to-cell spread than a chimeric SN virus in which only the G gene was replaced. Together, these data indicate that both G and M play an important role in RV pathogenesis by regulating virus replication and facilitating cell-to-cell spread.

  1. The Glycoprotein and the Matrix Protein of Rabies Virus Affect Pathogenicity by Regulating Viral Replication and Facilitating Cell-to-Cell Spread▿

    Science.gov (United States)

    Pulmanausahakul, Rojjanaporn; Li, Jianwei; Schnell, Matthias J.; Dietzschold, Bernhard

    2008-01-01

    While the glycoprotein (G) of rabies virus (RV) is known to play a predominant role in the pathogenesis of rabies, the function of the RV matrix protein (M) in RV pathogenicity is not completely clear. To further investigate the roles of these proteins in viral pathogenicity, we constructed chimeric recombinant viruses by exchanging the G and M genes of the attenuated SN strain with those of the highly pathogenic SB strain. Infection of mice with these chimeric viruses revealed a significant increase in the pathogenicity of the SN strain bearing the RV G from the pathogenic SB strain. Moreover, the pathogenicity was further increased when both G and M from SB were introduced into SN. Interestingly, the replacement of the G or M gene or both in SN by the corresponding genes of SB was associated with a significant decrease in the rate of viral replication and viral RNA synthesis. In addition, a chimeric SN virus bearing both the M and G genes from SB exhibited more efficient cell-to-cell spread than a chimeric SN virus in which only the G gene was replaced. Together, these data indicate that both G and M play an important role in RV pathogenesis by regulating virus replication and facilitating cell-to-cell spread. PMID:18094173

  2. RNA Binding Protein RBM38 Regulates Expression of the 11-kDa Protein of Parvovirus B19 which Facilitates Viral DNA Replication.

    Science.gov (United States)

    Ganaie, Safder S; Chen, Aaron Yun; Huang, Chun; Xu, Peng; Kleiboeker, Steve; Du, Aifang; Qiu, Jianming

    2018-02-07

    Human parvovirus B19 (B19V) expresses a single precursor mRNA (pre-mRNA), which undergoes alternative splicing and alternative polyadenylation to generate 12 viral mRNA transcripts that encode two structural proteins (VP1 and VP2) and three nonstructural proteins (NS1, 7.5-kDa, and 11-kDa). Splicing at the second 5' donor site (D2) of the B19V pre-mRNA is essential for the expression of VP2 and 11-kDa. We have previously identified that a cis -acting intronic splicing enhancer 2 (ISE2) that lies immediately after the D2 site facilitates recognition of the D2 donor for its efficient splicing. In this study, we report that ISE2 is critical for expression of the 11-kDa viral non-structural protein. We found that ISE2 harbors a consensus RNA-binding motif protein 38 (RBM38) binding sequence-5' -UGUGUG-3'. RBM38 is expressed during the middle stage of erythropoiesis. We first confirmed that the RBM38 binds specifically with the ISE2 element in vitro. Knockdown of RBM38 significantly decreases the level of the spliced mRNA at D2 that encodes 11-kDa protein and, thereafter, expression of the 11-kDa protein, but not the D2-spliced mRNA that encodes VP2. Importantly, we found that the 11-kDa protein enhances viral DNA replication and virion release. Accordingly, knockdown of RBM38 decreases virus replication via downregulating 11-kDa expression. Taken together, these results suggest that the 11-kDa protein facilitates B19V DNA replication, and that RBM38 is an essential host factor for B19V pre-mRNA splicing and for the expression of the 11-kDa protein. IMPORTANCE B19V is a human pathogen that can cause fifth disease, arthropathy, anemia in immune compromised patients and sickle cell disease patients, myocarditis, and hydrops fetalis in pregnant women. Human erythroid progenitor cells (EPCs) are most susceptible to B19V infection and fully support viral DNA replication. The exclusive tropism of B19V to erythroid lineage cells is not only dependent on the expression of viral

  3. Multiscale model for the effects of adaptive immunity suppression on the viral therapy of cancer

    International Nuclear Information System (INIS)

    Paiva, Leticia R; Silva, Hallan S; Ferreira, Silvio C; Martins, Marcelo L

    2013-01-01

    Oncolytic virotherapy—the use of viruses that specifically kill tumor cells—is an innovative and highly promising route for treating cancer. However, its therapeutic outcomes are mainly impaired by the host immune response to the viral infection. In this paper, we propose a multiscale mathematical model to study how the immune response interferes with the viral oncolytic activity. The model assumes that cytotoxic T cells can induce apoptosis in infected cancer cells and that free viruses can be inactivated by neutralizing antibodies or cleared at a constant rate by the innate immune response. Our simulations suggest that reprogramming the immune microenvironment in tumors could substantially enhance the oncolytic virotherapy in immune-competent hosts. Viable routes to such reprogramming are either in situ virus-mediated impairing of CD8 + T cells motility or blockade of B and T lymphocytes recruitment. Our theoretical results can shed light on the design of viral vectors or new protocols with neat potential impacts on the clinical practice. (paper)

  4. Dual role of TRBP in HIV replication and RNA interference: viral diversion of a cellular pathway or evasion from antiviral immunity?

    Directory of Open Access Journals (Sweden)

    Clerzius Guerline

    2005-10-01

    Full Text Available Abstract Increasing evidence indicates that RNA interference (RNAi may be used to provide antiviral immunity in mammalian cells. Human micro (miRNAs can inhibit the replication of a primate virus, whereas a virally-encoded miRNA from HIV inhibits its own replication. Indirect proof comes from RNAi suppressors encoded by mammalian viruses. Influenza NS1 and Vaccinia E3L proteins can inhibit RNAi in plants, insects and worms. HIV-1 Tat protein and Adenovirus VA RNAs act as RNAi suppressors in mammalian cells. Surprisingly, many RNAi suppressors are also inhibitors of the interferon (IFN-induced protein kinase R (PKR but the potential overlap between the RNAi and the IFN pathways remains to be determined. The link between RNAi as an immune response and the IFN pathway may be formed by a cellular protein, TRBP, which has a dual role in HIV replication and RNAi. TRBP has been isolated as an HIV-1 TAR RNA binding protein that increases HIV expression and replication by inhibiting PKR and by increasing translation of structured RNAs. A recent report published in the Journal of Virology shows that the poor replication of HIV in astrocytes is mainly due to a heightened PKR response that can be overcome by supplying TRBP exogenously. In two recent papers published in Nature and EMBO Reports, TRBP is now shown to interact with Dicer and to be required for RNAi mediated by small interfering (si and micro (miRNAs. The apparent discrepancy between TRBP requirement in RNAi and in HIV replication opens the hypotheses that RNAi may be beneficial for HIV-1 replication or that HIV-1 may evade the RNAi restriction by diverting TRBP from Dicer and use it for its own benefit.

  5. Equine viperin restricts equine infectious anemia virus replication by inhibiting the production and/or release of viral Gag, Env, and receptor via distortion of the endoplasmic reticulum.

    Science.gov (United States)

    Tang, Yan-Dong; Na, Lei; Zhu, Chun-Hui; Shen, Nan; Yang, Fei; Fu, Xian-Qiu; Wang, Yu-Hong; Fu, Li-Hua; Wang, Jia-Yi; Lin, Yue-Zhi; Wang, Xue-Feng; Wang, Xiaojun; Zhou, Jian-Hua; Li, Cheng-Yao

    2014-11-01

    Viperin is an endoplasmic reticulum (ER)-associated multifunctional protein that regulates virus replication and possesses broad antiviral activity. In many cases, viperin interferes with the trafficking and budding of viral structural proteins by distorting the membrane transportation system. The lentivirus equine infectious anemia virus (EIAV) has been studied extensively. In this study, we examined the restrictive effect of equine viperin (eViperin) on EIAV replication and investigated the possible molecular basis of this restriction to obtain insights into the effect of this cellular factor on retroviruses. We demonstrated that EIAV infection of primary equine monocyte-derived macrophages (eMDMs) upregulated the expression of eViperin. The overexpression of eViperin significantly inhibited the replication of EIAV in eMDMs, and knockdown of eViperin transcription enhanced the replication of EIAV in eMDMs by approximately 45.8%. Further experiments indicated that eViperin restricts EIAV at multiple steps of viral replication. The overexpression of eViperin inhibited EIAV Gag release. Both the α-helix domain and radical S-adenosylmethionine (SAM) domain were required for this activity. However, the essential motifs in SAM were different from those reported for the inhibition of HIV-1 Gag by human viperin. Furthermore, eViperin disrupted the synthesis of both EIAV Env and receptor, which consequently inhibited viral production and entry, respectively, and this disruption was dependent on the eViperin α-helix domain. Using immunofluorescence assays and electron microscopy, we demonstrated that the α-helix domain is responsible for the distortion of the endoplasmic reticulum (ER). Finally, EIAV did not exhibit counteracting eViperin at the protein level. In previous studies, viperin was indicated as restricting virus replications primarily by the inhibition of virus budding. Here, we show that viperin may have multiple antiviral mechanisms, including the reduction

  6. The P2 of Wheat yellow mosaic virus rearranges the endoplasmic reticulum and recruits other viral proteins into replication-associated inclusion bodies.

    Science.gov (United States)

    Sun, Liying; Andika, Ida Bagus; Shen, Jiangfeng; Yang, Di; Chen, Jianping

    2014-06-01

    Viruses commonly modify host endomembranes to facilitate biological processes in the viral life cycle. Infection by viruses belonging to the genus Bymovirus (family Potyviridae) has long been known to induce the formation of large membranous inclusion bodies in host cells, but their assembly and biological roles are still unclear. Immunoelectron microscopy of cells infected with the bymovirus Wheat yellow mosaic virus (WYMV) showed that P1, P2 and P3 are the major viral protein constituents of the membranous inclusions, whereas NIa-Pro (nuclear inclusion-a protease) and VPg (viral protein genome-linked) are probable minor components. P1, P2 and P3 associated with the endoplasmic reticulum (ER), but only P2 was able to rearrange ER and form large aggregate structures. Bioinformatic analyses and chemical experiments showed that P2 is an integral membrane protein and depends on the active secretory pathway to form aggregates of ER membranes. In planta and in vitro assays demonstrated that P2 interacts with P1, P3, NIa-Pro or VPg and recruits these proteins into the aggregates. In vivo RNA labelling using WYMV-infected wheat protoplasts showed that the synthesis of viral RNAs occurs in the P2-associated inclusions. Our results suggest that P2 plays a major role in the formation of membranous compartments that house the genomic replication of WYMV. © 2013 BSPP AND JOHN WILEY & SONS LTD.

  7. African swine fever virus encodes for an E2-ubiquitin conjugating enzyme that is mono- and di-ubiquitinated and required for viral replication cycle.

    Science.gov (United States)

    Freitas, Ferdinando B; Frouco, Gonçalo; Martins, Carlos; Ferreira, Fernando

    2018-02-22

    African swine fever virus is the etiological agent of a contagious and fatal acute haemorrhagic viral disease for which there are no vaccines or therapeutic options. The ASFV encodes for a putative E2 ubiquitin conjugating enzyme (ORF I215L) that shows sequence homology with eukaryotic counterparts. In the present study, we showed that pI215L acts as an E2-ubiquitin like enzyme in a large range of pH values and temperatures, after short incubation times. Further experiments revealed that pI215L is polyubiquitinated instead of multi-mono-ubiquitinated and Cys85 residue plays an essential role in the transthioesterification reaction. In infected cells, I215L gene is transcribed from 2 hours post infection and immunoblot analysis confirmed that pI215L is expressed from 4 hpi. Immunofluorescence studies revealed that pI215L is recruited to viral factories from 8 hpi and a diffuse distribution pattern throughout the nucleus and cytoplasm. siRNA studies suggested that pI215L plays a critical role in the transcription of late viral genes and viral DNA replication. Altogether, our results emphasize the potential use of this enzyme as target for drug and vaccine development against ASF.

  8. Transmissible gastroenteritis coronavirus genome packaging signal is located at the 5' end of the genome and promotes viral RNA incorporation into virions in a replication-independent process.

    Science.gov (United States)

    Morales, Lucia; Mateos-Gomez, Pedro A; Capiscol, Carmen; del Palacio, Lorena; Enjuanes, Luis; Sola, Isabel

    2013-11-01

    Preferential RNA packaging in coronaviruses involves the recognition of viral genomic RNA, a crucial process for viral particle morphogenesis mediated by RNA-specific sequences, known as packaging signals. An essential packaging signal component of transmissible gastroenteritis coronavirus (TGEV) has been further delimited to the first 598 nucleotides (nt) from the 5' end of its RNA genome, by using recombinant viruses transcribing subgenomic mRNA that included potential packaging signals. The integrity of the entire sequence domain was necessary because deletion of any of the five structural motifs defined within this region abrogated specific packaging of this viral RNA. One of these RNA motifs was the stem-loop SL5, a highly conserved motif in coronaviruses located at nucleotide positions 106 to 136. Partial deletion or point mutations within this motif also abrogated packaging. Using TGEV-derived defective minigenomes replicated in trans by a helper virus, we have shown that TGEV RNA packaging is a replication-independent process. Furthermore, the last 494 nt of the genomic 3' end were not essential for packaging, although this region increased packaging efficiency. TGEV RNA sequences identified as necessary for viral genome packaging were not sufficient to direct packaging of a heterologous sequence derived from the green fluorescent protein gene. These results indicated that TGEV genome packaging is a complex process involving many factors in addition to the identified RNA packaging signal. The identification of well-defined RNA motifs within the TGEV RNA genome that are essential for packaging will be useful for designing packaging-deficient biosafe coronavirus-derived vectors and providing new targets for antiviral therapies.

  9. CD4 decline is associated with increased risk of cardiovascular disease, cancer, and death in virally suppressed patients with HIV

    DEFF Research Database (Denmark)

    Helleberg, Marie; Kronborg, Gitte; Larsen, Carsten

    2013-01-01

    immunodeficiency virus (HIV) were followed in the Danish nationwide, population-based cohort study in the period 1995-2010 with quarterly CD4 measurements. Associations between a CD4 decline of ≥30% and cardiovascular disease, cancer, and death were analyzed using Poisson regression with date of CD4 decline...... as a time-updated variable. Results. We followed 2584 virally suppressed HIV patients for 13 369 person-years (PY; median observation time, 4.7 years). Fifty-six patients developed CD4 decline (incidence rate, 4.2/1000 PY [95% confidence interval {CI}, 3.2-5.4]). CD4 counts dropped from a median of 492...

  10. Role of ATM in the Formation of the Replication Compartment during Lytic Replication of Epstein-Barr Virus in Nasopharyngeal Epithelial Cells

    Science.gov (United States)

    Hau, Pok Man; Deng, Wen; Jia, Lin; Yang, Jie; Tsurumi, Tatsuya; Chiang, Alan Kwok Shing; Huen, Michael Shing-Yan

    2014-01-01

    ABSTRACT Epstein-Barr virus (EBV), a type of oncogenic herpesvirus, is associated with human malignancies. Previous studies have shown that lytic reactivation of EBV in latently infected cells induces an ATM-dependent DNA damage response (DDR). The involvement of ATM activation has been implicated in inducing viral lytic gene transcription to promote lytic reactivation. Its contribution to the formation of a replication compartment during lytic reactivation of EBV remains poorly defined. In this study, the role of ATM in viral DNA replication was investigated in EBV-infected nasopharyngeal epithelial cells. We observed that induction of lytic infection of EBV triggers ATM activation and localization of DDR proteins at the viral replication compartments. Suppression of ATM activity using a small interfering RNA (siRNA) approach or a specific chemical inhibitor profoundly suppressed replication of EBV DNA and production of infectious virions in EBV-infected cells induced to undergo lytic reactivation. We further showed that phosphorylation of Sp1 at the serine-101 residue is essential in promoting the accretion of EBV replication proteins at the replication compartment, which is crucial for replication of viral DNA. Knockdown of Sp1 expression by siRNA effectively suppressed the replication of viral DNA and localization of EBV replication proteins to the replication compartments. Our study supports an important role of ATM activation in lytic reactivation of EBV in epithelial cells, and phosphorylation of Sp1 is an essential process downstream of ATM activation involved in the formation of viral replication compartments. Our study revealed an essential role of the ATM-dependent DDR pathway in lytic reactivation of EBV, suggesting a potential antiviral replication strategy using specific DDR inhibitors. IMPORTANCE Epstein-Barr virus (EBV) is closely associated with human malignancies, including undifferentiated nasopharyngeal carcinoma (NPC), which has a high

  11. Inhibition of viral replication reduces regulatory T cells and enhances the antiviral immune response in chronic hepatitis B.

    Science.gov (United States)

    Stoop, Jeroen N; van der Molen, Renate G; Kuipers, Ernst J; Kusters, Johannes G; Janssen, Harry L A

    2007-04-25

    Regulatory T cells (Treg) play a key role in the impaired immune response that is typical for a chronic Hepatitis B virus (HBV) infection. To gain more insight in the mechanism that is responsible for this impaired immune response, the effect of viral load reduction resulting from treatment with the nucleotide analogue adefovir dipivoxil on the percentages of Treg and HBV-specific T-cell responses was analyzed. Peripheral blood mononuclear cells (PBMC) of 12 patients were collected at baseline and during treatment. In parallel to the decline in viral load, we found a decline in circulating Treg, combined with an increase in HBV core antigen-specific IFN-gamma production and proliferation. The production of IL10 did not decrease during therapy. In conclusion, adefovir induced viral load reduction results in a decline of circulating Treg together with a partial recovery of the immune response.

  12. Inhibition of viral replication reduces regulatory T cells and enhances the antiviral immune response in chronic hepatitis B

    International Nuclear Information System (INIS)

    Stoop, Jeroen N.; Molen, Renate G. van der; Kuipers, Ernst J.; Kusters, Johannes G.; Janssen, Harry L.A.

    2007-01-01

    Regulatory T cells (Treg) play a key role in the impaired immune response that is typical for a chronic Hepatitis B virus (HBV) infection. To gain more insight in the mechanism that is responsible for this impaired immune response, the effect of viral load reduction resulting from treatment with the nucleotide analogue adefovir dipivoxil on the percentages of Treg and HBV-specific T-cell responses was analyzed. Peripheral blood mononuclear cells (PBMC) of 12 patients were collected at baseline and during treatment. In parallel to the decline in viral load, we found a decline in circulating Treg, combined with an increase in HBV core antigen-specific IFN-γ production and proliferation. The production of IL10 did not decrease during therapy. In conclusion, adefovir induced viral load reduction results in a decline of circulating Treg together with a partial recovery of the immune response

  13. The helicase senataxin suppresses the antiviral transcriptional response and controls viral biogenesis

    Science.gov (United States)

    Miller, Matthew S.; Rialdi, Alexander; Ho, Jessica Sook Yuin; Tilove, Micah; Martinez-Gil, Luis; Moshkina, Natasha P.; Peralta, Zuleyma; Noel, Justine; Melegari, Camilla; Maestre, Ana; Mitsopoulos, Panagiotis; Madrenas, Joaquín; Heinz, Sven; Benner, Chris; Young, John A. T.; Feagins, Alicia R.; Basler, Christopher; Fernandez-Sesma, Ana; Becherel, Olivier J.; Lavin, Martin F.; van Bakel, Harm; Marazzi, Ivan

    2015-01-01

    The human helicase senataxin (SETX) is implicated in the neurodegenerative diseases amyotrophic lateral sclerosis (ALS4) and ataxia with oculomotor apraxia (AOA2). Here, we reveal a role for SETX in controlling the antiviral response. Cells depleted for SETX and AOA2 patient-derived SETX-deficient cells exhibit increased expression of antiviral mediators in response to infection. Mechanistically, we propose a model whereby SETX attenuates RNA polymerase II (RNAPII) activity at genes stimulated upon viral sensing, thus controlling the magnitude of the host response to pathogens and the biogenesis of numerous RNA viruses (e. g. Influenza A virus and West Nile virus). Our data indicate a potentially causal link between SETX inborn errors, susceptibility to infection and development of neurologic disorders. PMID:25822250

  14. A positive-strand RNA virus uses alternative protein-protein interactions within a viral protease/cofactor complex to switch between RNA replication and virion morphogenesis

    Science.gov (United States)

    Rey, Félix A.

    2017-01-01

    The viruses of the family Flaviviridae possess a positive-strand RNA genome and express a single polyprotein which is processed into functional proteins. Initially, the nonstructural (NS) proteins, which are not part of the virions, form complexes capable of genome replication. Later on, the NS proteins also play a critical role in virion formation. The molecular basis to understand how the same proteins form different complexes required in both processes is so far unknown. For pestiviruses, uncleaved NS2-3 is essential for virion morphogenesis while NS3 is required for RNA replication but is not functional in viral assembly. Recently, we identified two gain of function mutations, located in the C-terminal region of NS2 and in the serine protease domain of NS3 (NS3 residue 132), which allow NS2 and NS3 to substitute for uncleaved NS2-3 in particle assembly. We report here the crystal structure of pestivirus NS3-4A showing that the NS3 residue 132 maps to a surface patch interacting with the C-terminal region of NS4A (NS4A-kink region) suggesting a critical role of this contact in virion morphogenesis. We show that destabilization of this interaction, either by alanine exchanges at this NS3/4A-kink interface, led to a gain of function of the NS3/4A complex in particle formation. In contrast, RNA replication and thus replicase assembly requires a stable association between NS3 and the NS4A-kink region. Thus, we propose that two variants of NS3/4A complexes exist in pestivirus infected cells each representing a basic building block required for either RNA replication or virion morphogenesis. This could be further corroborated by trans-complementation studies with a replication-defective NS3/4A double mutant that was still functional in viral assembly. Our observations illustrate the presence of alternative overlapping surfaces providing different contacts between the same proteins, allowing the switch from RNA replication to virion formation. PMID:28151973

  15. A positive-strand RNA virus uses alternative protein-protein interactions within a viral protease/cofactor complex to switch between RNA replication and virion morphogenesis.

    Directory of Open Access Journals (Sweden)

    Danilo Dubrau

    2017-02-01

    Full Text Available The viruses of the family Flaviviridae possess a positive-strand RNA genome and express a single polyprotein which is processed into functional proteins. Initially, the nonstructural (NS proteins, which are not part of the virions, form complexes capable of genome replication. Later on, the NS proteins also play a critical role in virion formation. The molecular basis to understand how the same proteins form different complexes required in both processes is so far unknown. For pestiviruses, uncleaved NS2-3 is essential for virion morphogenesis while NS3 is required for RNA replication but is not functional in viral assembly. Recently, we identified two gain of function mutations, located in the C-terminal region of NS2 and in the serine protease domain of NS3 (NS3 residue 132, which allow NS2 and NS3 to substitute for uncleaved NS2-3 in particle assembly. We report here the crystal structure of pestivirus NS3-4A showing that the NS3 residue 132 maps to a surface patch interacting with the C-terminal region of NS4A (NS4A-kink region suggesting a critical role of this contact in virion morphogenesis. We show that destabilization of this interaction, either by alanine exchanges at this NS3/4A-kink interface, led to a gain of function of the NS3/4A complex in particle formation. In contrast, RNA replication and thus replicase assembly requires a stable association between NS3 and the NS4A-kink region. Thus, we propose that two variants of NS3/4A complexes exist in pestivirus infected cells each representing a basic building block required for either RNA replication or virion morphogenesis. This could be further corroborated by trans-complementation studies with a replication-defective NS3/4A double mutant that was still functional in viral assembly. Our observations illustrate the presence of alternative overlapping surfaces providing different contacts between the same proteins, allowing the switch from RNA replication to virion formation.

  16. Social Capital, Depressive Symptoms, and HIV Viral Suppression Among Young Black, Gay, Bisexual and Other Men Who Have Sex with Men Living with HIV.

    Science.gov (United States)

    Hussen, Sophia A; Easley, Kirk A; Smith, Justin C; Shenvi, Neeta; Harper, Gary W; Camacho-Gonzalez, Andres F; Stephenson, Rob; Del Rio, Carlos

    2018-04-04

    Social capital, the sum of an individual's resource-containing social network connections, has been proposed as a facilitator of successful HIV care engagement. We explored relationships between social capital, psychological covariates (depression, stigma and internalized homonegativity), and viral suppression in a sample of young Black gay, bisexual and other men who have sex with men (YB-GBMSM). We recruited 81 HIV-positive YB-GBMSM 18-24 years of age from a clinic setting. Participants completed a cross-sectional survey, and HIV-1 viral load (VL) measurements were extracted from the medical record. Sixty-five percent (65%) were virally suppressed (HIV-1 VL ≤ 40 copies/ml). Forty-seven percent (47%) had a positive depression screen. Depressive symptoms affected viral suppression differently in YB-GBMSM with lower vs. higher social capital (p = 0.046, test for statistical interaction between depression and social capital). The odds of viral suppression among YB-GBMSM with lower social capital was 93% lower among those with depressive symptoms (OR 0.07, p = 0.002); however, there was no association between depressive symptoms and viral suppression among those with higher social capital. Our results suggest that social capital may buffer the strong negative effects of depressive symptoms on clinical outcomes in YB-GBMSM living with HIV. In addition to treating depression, there is a role for interventions to augment social capital among YB-GBMSM living with HIV as a strategy for enhancing care engagement.

  17. The AP-1 binding sites located in the pol gene intragenic regulatory region of HIV-1 are important for viral replication.

    Directory of Open Access Journals (Sweden)

    Laurence Colin

    Full Text Available Our laboratory has previously identified an important intragenic region in the human immunodeficiency virus type 1 (HIV-1 genome, whose complete functional unit is composed of the 5103 fragment, the DNaseI-hypersensitive site HS7 and the 5105 fragment. These fragments (5103 and 5105 both exhibit a phorbol 12-myristate 13-acetate (PMA-inducible enhancer activity on the herpes simplex virus thymidine kinase promoter. Here, we characterized the three previously identified AP-1 binding sites of fragment 5103 by showing the PMA-inducible in vitro binding and in vivo recruitment of c-Fos, JunB and JunD to this fragment located at the end of the pol gene. Functional analyses demonstrated that the intragenic AP-1 binding sites are fully responsible for the PMA-dependent enhancer activity of fragment 5103. Moreover, infection of T-lymphoid Jurkat and promonocytic U937 cells with wild-type and mutant viruses demonstrated that mutations of the intragenic AP-1 sites individually or in combination altered HIV-1 replication. Importantly, mutations of the three intragenic AP-1 sites led to a decreased in vivo recruitment of RNA polymerase II to the viral promoter, strongly supporting that the deleterious effect of these mutations on viral replication occurs, at least partly, at the transcriptional level. Single-round infections of monocyte-derived macrophages confirmed the importance of intragenic AP-1 sites for HIV-1 infectivity.

  18. The formation and modification of chromatin-like structure of human parvovirus B19 regulate viral genome replication and RNA processing.

    Science.gov (United States)

    Xu, Huanzhou; Hao, Sujuan; Zhang, Junmei; Chen, Zhen; Wang, Hanzhong; Guan, Wuxiang

    2017-03-15

    B19 virus (B19V) is a single stranded virus in the genus of Erythroparvovirus in the family of Parvoviridae. One of the limiting steps of B19V infection is the replication of viral genome which affected the alternative processing of its RNA. Minute virus of mice (MVM) and adeno-associated virus (AAV) has been reported to form chromatin-like structure within hours after infection of cells. However, the role of chromatin-like structure is unclear. In the present study, we found that B19V formed chromatin-like structure after 12h when B19V infectious clone was co-transfected with pHelper plasmid to HEK293T cells. Interestingly, the inhibitor of DNA methyl-transferase (5-Aza-2'-deoxycytidine, DAC) inhibited not only the formation of chromatin-like structure, but also the replication of the viral genomic DNA. More importantly, the splicing of the second intron at splice acceptor sites (A2-1, and A2-2) were reduced and polyadenylation at (pA)p increased when transfected HEK293T cells were treated with DAC. Our results showed that the formation and modification of chromatin-like structure are a new layer to regulate B19V gene expression and RNA processing. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. The AP-1 Binding Sites Located in the pol Gene Intragenic Regulatory Region of HIV-1 Are Important for Viral Replication

    Science.gov (United States)

    Colin, Laurence; Vandenhoudt, Nathalie; de Walque, Stéphane; Van Driessche, Benoît; Bergamaschi, Anna; Martinelli, Valérie; Cherrier, Thomas; Vanhulle, Caroline; Guiguen, Allan; David, Annie; Burny, Arsène; Herbein, Georges; Pancino, Gianfranco

    2011-01-01

    Our laboratory has previously identified an important intragenic region in the human immunodeficiency virus type 1 (HIV-1) genome, whose complete functional unit is composed of the 5103 fragment, the DNaseI-hypersensitive site HS7 and the 5105 fragment. These fragments (5103 and 5105) both exhibit a phorbol 12-myristate 13-acetate (PMA)-inducible enhancer activity on the herpes simplex virus thymidine kinase promoter. Here, we characterized the three previously identified AP-1 binding sites of fragment 5103 by showing the PMA-inducible in vitro binding and in vivo recruitment of c-Fos, JunB and JunD to this fragment located at the end of the pol gene. Functional analyses demonstrated that the intragenic AP-1 binding sites are fully responsible for the PMA-dependent enhancer activity of fragment 5103. Moreover, infection of T-lymphoid Jurkat and promonocytic U937 cells with wild-type and mutant viruses demonstrated that mutations of the intragenic AP-1 sites individually or in combination altered HIV-1 replication. Importantly, mutations of the three intragenic AP-1 sites led to a decreased in vivo recruitment of RNA polymerase II to the viral promoter, strongly supporting that the deleterious effect of these mutations on viral replication occurs, at least partly, at the transcriptional level. Single-round infections of monocyte-derived macrophages confirmed the importance of intragenic AP-1 sites for HIV-1 infectivity. PMID:21526160

  20. [Effect of the gardenia extracts-T9 on viral replication and IFN-gamma mRNA in Herpes simplex virus type-1 infected mice brains].

    Science.gov (United States)

    Shi, Yu-jing; Huang, Yang; Jiang, Jing; Guo, Shan-shan; Su, Dan; Zhao, Ye; Gao, Ying-jie; Cui, Xiao-lan

    2009-01-01

    RT-PCR was used to detect expression level of VP16 mRNA and IFN-gamma mRNA in Herpes simplex virus type-1 infected mice brains at 4th day, 7th day, 10th day, 14th day, 21st day post infection and investigate the effects of the Gardenia extracts-T9 on viral replication and host immunity. The results showed that expression of VP16 mRNA in Gardenia extracts-T9 high dose and low dose group were both lower than that in virus control group at same time point. Relative VP16 mRNA expression in low dose group decreased at 21st day and relative VP16 mRNA expression in high dose group decreased continuously. Relative expression of IFN-gamma mRNA in high dose and low dose groups were both higher than that in virus control group at all time point except the 4th day. IFN-gamma mRNA in low dose group increased from the 4th day till the 14th day, and after the 14th day, the expression decreased slightly. Relative IFN-gamma mRNA in high dose group maintained increasing from 4th day till 21st day. Base on these results, we conclude that Gardenia extracts-T9 might exert the inhibition effect of viral replication by upregulating expression of IFN-gamma mRNA.

  1. Association of polioviral proteins of the P2 genomic region with the viral replication complex and virus-induced membrane synthesis as visualized by electron microscopic immunocytochemistry and autoradiography.

    Science.gov (United States)

    Bienz, K; Egger, D; Pasamontes, L

    1987-09-01

    Using high resolution electron microscopic autoradiography and immunocytochemistry with monoclonal antibodies against poliovirus proteins of the P2 genomic region, the location of these proteins in respect to the virus-induced vesicle formation and the viral RNA synthesis was followed during the viral replication cycle. It was found that P2 proteins become rER associated soon after their synthesis. At the site of protein and rER interaction, electron-dense patches appear. Simultaneously, membrane protrusions grow and form vesicles which finally budd off, carrying the patches on their outer surface. As shown by autoradiography, these patches are the site of viral RNA replication and, therefore, they represent the poliovirus replication complex. The vesicles with the replication complex, including replicating and replicated viral RNA, move away from the rER to form a continuously growing vesiculated area in the center of the infected cell, where virus maturation takes place. A likely function of the 2C protein is to attach the replication complex, or some of its components, to the vesicular membranes.

  2. Cytoplasmic ATR Activation Promotes Vaccinia Virus Genome Replication

    Directory of Open Access Journals (Sweden)

    Antonio Postigo

    2017-05-01

    Full Text Available In contrast to most DNA viruses, poxviruses replicate their genomes in the cytoplasm without host involvement. We find that vaccinia virus induces cytoplasmic activation of ATR early during infection, before genome uncoating, which is unexpected because ATR plays a fundamental nuclear role in maintaining host genome integrity. ATR, RPA, INTS7, and Chk1 are recruited to cytoplasmic DNA viral factories, suggesting canonical ATR pathway activation. Consistent with this, pharmacological and RNAi-mediated inhibition of canonical ATR signaling suppresses genome replication. RPA and the sliding clamp PCNA interact with the viral polymerase E9 and are required for DNA replication. Moreover, the ATR activator TOPBP1 promotes genome replication and associates with the viral replisome component H5. Our study suggests that, in contrast to long-held beliefs, vaccinia recruits conserved components of the eukaryote DNA replication and repair machinery to amplify its genome in the host cytoplasm.

  3. G3BP1 restricts HIV-1 replication in macrophages and T-cells by sequestering viral RNA

    NARCIS (Netherlands)

    Cobos Jiménez, Viviana; Martinez, Fernando O.; Booiman, Thijs; van Dort, Karel A.; van de Klundert, Maarten A. A.; Gordon, Siamon; Geijtenbeek, Teunis B. H.; Kootstra, Neeltje A.

    2015-01-01

    HIV-1 exploits the cellular machinery for replication and therefore several interactions with cellular factors take place, some of which are yet unknown. We identified GTPase-activating protein-(SH3 domain)-binding protein 1 (G3BP1) as a cellular factor that restricts HIV-1, by analyzing

  4. Early events in the pathogenesis of foot-and-mouth disease in pigs; identification of oropharyngeal tonsils as sites of primary and sustained viral replication.

    Directory of Open Access Journals (Sweden)

    Carolina Stenfeldt

    Full Text Available A time-course study was performed to elucidate the early events of foot-and-mouth disease virus (FMDV infection in pigs subsequent to simulated natural, intra-oropharyngeal, inoculation. The earliest detectable event was primary infection in the lingual and paraepiglottic tonsils at 6 hours post inoculation (hpi characterized by regional localization of viral RNA, viral antigen, and infectious virus. At this time FMDV antigen was localized in cytokeratin-positive epithelial cells and CD172a-expressing leukocytes of the crypt epithelium of the paraepiglottic tonsils. De novo replication of FMDV was first detected in oropharyngeal swab samples at 12 hpi and viremia occurred at 18-24 hpi, approximately 24 hours prior to the appearance of vesicular lesions. From 12 through 78 hpi, microscopic detection of FMDV was consistently localized to cytokeratin-positive cells within morphologically characteristic segments of oropharyngeal tonsil crypt epithelium. During this period, leukocyte populations expressing CD172a, SLA-DQ class II and/or CD8 were found in close proximity to infected epithelial cells, but with little or no co-localization with viral proteins. Similarly, M-cells expressing cytokeratin-18 did not co-localize with FMDV proteins. Intra-epithelial micro-vesicles composed of acantholytic epithelial cells expressing large amounts of structural and non-structural FMDV proteins were present within crypts of the tonsil of the soft palate during peak clinical infection. These findings inculpate the paraepiglottic tonsils as the primary site of FMDV infection in pigs exposed via the gastrointestinal tract. Furthermore, the continuing replication of FMDV in the oropharyngeal tonsils during viremia and peak clinical infection with no concurrent amplification of virus occurring in the lower respiratory tract indicates that these sites are the major source of shedding of FMDV from pigs.

  5. Down-regulation of viral replication by adenoviral-mediated expression of siRNA against cellular cofactors for hepatitis C virus

    International Nuclear Information System (INIS)

    Zhang Jing; Yamada, Osamu; Sakamoto, Takashi; Yoshida, Hiroshi; Iwai, Takahiro; Matsushita, Yoshihisa; Shimamura, Hideo; Araki, Hiromasa; Shimotohno, Kunitada

    2004-01-01

    Small interfering RNA (siRNA) is currently being evaluated not only as a powerful tool for functional genomics, but also as a potentially promising therapeutic agent for cancer and infectious diseases. Inhibitory effect of siRNA on viral replication has been demonstrated in multiple pathogenic viruses. However, because of the high sequence specificity of siRNA-mediated RNA degradation, antiviral efficacy of siRNA directed to viral genome will be largely limited by emergence of escape variants resistant to siRNA due to high mutation rates of virus, especially RNA viruses such as poliovirus and hepatitis C virus (HCV). To investigate the therapeutic feasibility of siRNAs specific for the putative cellular cofactors for HCV, we constructed adenovirus vectors expressing siRNAs against La, polypyrimidine tract-binding protein (PTB), subunit gamma of human eukaryotic initiation factors 2B (eIF2Bγ), and human VAMP-associated protein of 33 kDa (hVAP-33). Adenoviral-mediated expression of siRNAs markedly diminished expression of the endogenous genes, and silencing of La, PTB, and hVAP-33 by siRNAs substantially blocked HCV replication in Huh-7 cells. Thus, our studies demonstrate the feasibility and potential of adenoviral-delivered siRNAs specific for cellular cofactors in combating HCV infection, which can be used either alone or in combination with siRNA against viral genome to prevent the escape of mutant variants and provide additive or synergistic anti-HCV effects

  6. Dual role of novel ingenol derivatives from Euphorbia tirucalli in HIV replication: inhibition of de novo infection and activation of viral LTR.

    Directory of Open Access Journals (Sweden)

    Celina M Abreu

    Full Text Available HIV infection is not cleared by antiretroviral drugs due to the presence of latently infected cells that are not eliminated with current therapies and persist in the blood and organs of infected patients. New compounds to activate these latent reservoirs have been evaluated so that, along with HAART, they can be used to activate latent virus and eliminate the latently infected cells resulting in eradication of viral infection. Here we describe three novel diterpenes isolated from the sap of Euphorbia tirucalli, a tropical shrub. These molecules, identified as ingenols, were modified at carbon 3 and termed ingenol synthetic derivatives (ISD. They activated the HIV-LTR in reporter cell lines and human PBMCs with latent virus in concentrations as low as 10 nM. ISDs were also able to inhibit the replication of HIV-1 subtype B and C in MT-4 cells and human PBMCs at concentrations of EC50 0.02 and 0.09 µM respectively, which are comparable to the EC50 of some antiretroviral currently used in AIDS treatment. Control of viral replication may be caused by downregulation of surface CD4, CCR5 and CXCR4 observed after ISD treatment in vitro. These compounds appear to be less cytotoxic than other diterpenes such as PMA and prostratin, with effective dose versus toxic dose TI>400. Although the mechanisms of action of the three ISDs are primarily attributed to the PKC pathway, downregulation of surface receptors and stimulation of the viral LTR might be differentially modulated by different PKC isoforms.

  7. Small RNA binding is a common strategy to suppress RNA silencing by several viral suppressors

    Science.gov (United States)

    Lakatos, Lóránt; Csorba, Tibor; Pantaleo, Vitantonio; Chapman, Elisabeth J; Carrington, James C; Liu, Yu-Ping; Dolja, Valerian V; Calvino, Lourdes Fernández; López-Moya, Juan José; Burgyán, József

    2006-01-01

    RNA silencing is an evolutionarily conserved system that functions as an antiviral mechanism in higher plants and insects. To counteract RNA silencing, viruses express silencing suppressors that interfere with both siRNA- and microRNA-guided silencing pathways. We used comparative in vitro and in vivo approaches to analyse the molecular mechanism of suppression by three well-studied silencing suppressors. We found that silencing suppressors p19, p21 and HC-Pro each inhibit the intermediate step of RNA silencing via binding to siRNAs, although the molecular features required for duplex siRNA binding differ among the three proteins. None of the suppressors affected the activity of preassembled RISC complexes. In contrast, each suppressor uniformly inhibited the siRNA-initiated RISC assembly pathway by preventing RNA silencing initiator complex formation. PMID:16724105

  8. The X gene of adeno-associated virus 2 (AAV2) is involved in viral DNA replication.

    Science.gov (United States)

    Cao, Maohua; You, Hong; Hermonat, Paul L

    2014-01-01

    Adeno-associated virus (AAV) (type 2) is a popular human gene therapy vector with a long active transgene expression period and no reported vector-induced adverse reactions. Yet the basic molecular biology of this virus has not been fully addressed. One potential gene at the far 3' end of the AAV2 genome, previously referred to as X (nt 3929 to 4393), overlapping the 3' end of the cap gene, has never been characterized, although we did previously identify a promoter just up-stream (p81). Computer analysis suggested that X was involved in replication and transcription. The X protein was identified during active AAV2 replication using a polyclonal antibody against a peptide starting at amino acid 98. Reagents for the study of X included an AAV2 deletion mutant (dl78-91), a triple nucleotide substitution mutant that destroys all three 5' AUG-initiation products of X, with no effect on the cap coding sequence, and X-positive-293 cell lines. Here, we found that X up-regulated AAV2 DNA replication in differentiating keratinocytes (without helper virus, autonomous replication) and in various forms of 293 cell-based assays with help from wild type adenovirus type 5 (wt Ad5) or Ad5 helper plasmid (pHelper). The strongest contribution by X was seen in increasing wt AAV2 DNA replication in keratinocytes and dl78-91 in Ad5-infected X-positive-293 cell lines (both having multi-fold effects). Mutating the X gene in pAAV-RC (pAAV-RC-3Xneg) yielded approximately a ∼33% reduction in recombinant AAV vector DNA replication and virion production, but a larger effect was seen when using this same X-knockout AAV helper plasmid in X-positive-293 cell lines versus normal 293 cells (again, multi-fold). Taken together these data strongly suggest that AAV2 X encodes a protein involved in the AAV life cycle, particularly in increasing AAV2 DNA replication, and suggests that further studies are warranted.

  9. Retention in care, viral suppression, treatment adherence and quality of life in a public antiretroviral therapy program in Addis Ababa, Ethiopia

    NARCIS (Netherlands)

    Mekuria, L.A.

    2016-01-01

    In his thesis, Legese A. Mekuria presents the results of a PhD study which was undertaken in 10 health-care facilities in Addis Ababa, Ethiopia. The overall aim was to estimate retention in HIV care, viral suppression, medication adherence and patients’ health-related quality of life (HRQoL). An

  10. Long-term mortality in HIV patients virally suppressed for more than three years with incomplete CD4 recovery: a cohort study

    DEFF Research Database (Denmark)

    Engsig, Frederik Neess; Gerstoft, Jan; Kronborg, Gitte

    2010-01-01

    The mortality in patients with persistent low CD4 count despite several years of HAART with sustained viral suppression is poorly documented. We aimed to identify predictors for inadequate CD4 cell recovery and estimate mortality in patients with low CD4 count but otherwise successful HAART....

  11. Sesbania mosaic virus (SeMV infectious clone: possible mechanism of 3' and 5' end repair and role of polyprotein processing in viral replication.

    Directory of Open Access Journals (Sweden)

    Kunduri Govind

    Full Text Available Sesbania mosaic virus (SeMV is a positive stranded RNA virus belonging to the genus Sobemovirus. Construction of an infectious clone is an essential step for deciphering the virus gene functions in vivo. Using Agrobacterium based transient expression system we show that SeMV icDNA is infectious on Sesbania grandiflora and Cyamopsis tetragonoloba plants. The efficiency of icDNA infection was found to be significantly high on Cyamopsis plants when compared to that on Sesbania grandiflora. The coat protein could be detected within 6 days post infiltration in the infiltrated leaves. Different species of viral RNA (double stranded and single stranded genomic and subgenomic RNA could be detected upon northern analysis, suggesting that complete replication had taken place. Based on the analysis of the sequences at the genomic termini of progeny RNA from SeMV icDNA infiltrated leaves and those of its 3' and 5' terminal deletion mutants, we propose a possible mechanism for 3' and 5' end repair in vivo. Mutation of the cleavage sites in the polyproteins encoded by ORF 2 resulted in complete loss of infection by the icDNA, suggesting the importance of correct polyprotein processing at all the four cleavage sites for viral replication. Complementation analysis suggested that ORF 2 gene products can act in trans. However, the trans acting ability of ORF 2 gene products was abolished upon deletion of the N-terminal hydrophobic domain of polyprotein 2a and 2ab, suggesting that these products necessarily function at the replication site, where they are anchored to membranes.

  12. Effects of the W153L substitution in HIV reverse transcriptase on viral replication and drug resistance to multiple categories of reverse transcriptase inhibitors.

    Science.gov (United States)

    Xu, Hong-Tao; Colby-Germinario, Susan P; Oliveira, Maureen; Rajotte, Daniel; Bethell, Richard; Wainberg, Mark A

    2014-08-01

    A W153L substitution in HIV-1 reverse transcriptase (RT) was recently identified by selection with a novel nucleotide-competing RT inhibitor (NcRTI) termed compound A that is a member of the benzo[4,5]furo[3,2,d]pyrimidin-2-one NcRTI family of drugs. To investigate the impact of W153L, alone or in combination with the clinically relevant RT resistance substitutions K65R (change of Lys to Arg at position 65), M184I, K101E, K103N, E138K, and Y181C, on HIV-1 phenotypic susceptibility, viral replication, and RT enzymatic function, we generated recombinant RT enzymes and viruses containing each of these substitutions or various combinations of them. We found that W153L-containing viruses were impaired in viral replicative capacity and were hypersusceptible to tenofovir (TFV) while retaining susceptibility to most nonnucleoside RT inhibitors. The nucleoside 3TC retained potency against W153L-containing viruses but not when the M184I substitution was also present. W153L was also able to reverse the effects of the K65R substitution on resistance to TFV, and K65R conferred hypersusceptibility to compound A. Biochemical assays demonstrated that W153L alone or in combination with K65R, M184I, K101E, K103N, E138K, and Y181C impaired enzyme processivity and polymerization efficiency but did not diminish RNase H activity, providing mechanistic insights into the low replicative fitness associated with these substitutions. We show that the mechanism of the TFV hypersusceptibility conferred by W153L is mainly due to increased efficiency of TFV-diphosphate incorporation. These results demonstrate that compound A and/or derivatives thereof have the potential to be important antiretroviral agents that may be combined with tenofovir to achieve synergistic results. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  13. Detection of human parvovirus 4 viremia in the follow-up blood samples from seropositive individuals suggests the existence of persistent viral replication or reactivation of latent viral infection.

    Science.gov (United States)

    Chen, Mao-Yuan; Hung, Chien-Ching; Lee, Kuang-Lun

    2015-06-19

    The transmission routes for human parvovirus 4 (PARV4) infections in areas with high seroprevalence are not known. In the work described here, persistent PARV4 viral replication was investigated by conducting a longitudinal study. Ten healthcare workers each provided a blood sample at the beginning of the study (first sample) and 12 months later (second sample). The paired samples were tested for PARV4-positivity by immunoblotting analysis and nested polymerase chain reactions. IgG antibodies against PARV4 were detected in six participants, three of whom also had IgM antibodies against PARV4. The immunoblotting results did not vary over time. PARV4 DNA was detected in the first blood sample from one participant who had IgG antibodies against PARV4 and in the second blood samples from 2 participants who had IgG and IgM antibodies against PARV4. Detection of PARV4 DNA in the second blood samples from two seropositive participants suggests the existence of persistent PARV4 replication or reactivation of inactive virus in the tissues. The finding of persistent or intermittent PARV4 replication in individuals with past infections provides an important clue toward unraveling the non-parenteral transmission routes of PARV4 infection in areas where the virus is endemic.

  14. Predictors of CD4 health and viral suppression outcomes for formerly homeless people living with HIV/AIDS in scattered site supportive housing.

    Science.gov (United States)

    Bowen, Elizabeth A; Canfield, James; Moore, Suzanne; Hines, Midge; Hartke, Brent; Rademacher, Chrissy

    2017-11-01

    Stable housing is key to improving health outcomes for people living with HIV/AIDS. Though many formerly homeless HIV positive individuals reside in supportive housing, little research has examined biometric HIV health outcomes for residents of these programs. Through a community-based research partnership, this study analyzed secondary data from a Shelter Plus Care supportive housing program in Cincinnati, Ohio to examine the likelihood of participants achieving a healthy CD4 count (>500 cells/mm 3 ) and viral suppression (viral load housing and to identify participant characteristics associated with these outcomes. The study sample was 86 participants who entered the program between 2008 and 2016, including 50 current residents and 36 exited participants. Participants' average length of stay in Shelter Plus Care was 35.2 months (range 3.2-108.1 months) during the study period. Bivariate analysis indicated statistically significant improvements on both outcome variables, with 45% of participants achieving a healthy CD4 count and 79% achieving viral suppression by program exit or most recent time point. Participants who had health insurance at intake and who had never been incarcerated were more likely to achieve viral suppression, and longer length of stay in the program was also positively associated with viral suppression. These results add to the literature on the relationship between housing conditions and HIV health outcomes by demonstrating that residence in supportive housing is associated with improvements in CD4 count and viral load for a sample of formerly homeless persons living with HIV/AIDS, two-thirds of whom had co-occurring physical health, mental health, or substance abuse problems. Further research collaborations should expand on these findings to examine the service packages that are associated with optimal HIV health outcomes for supportive housing residents.

  15. High levels of viral suppression among East African HIV-infected women and men in serodiscordant partnerships initiating antiretroviral therapy with high CD4 counts and during pregnancy.

    Science.gov (United States)

    Mujugira, Andrew; Baeten, Jared; Kidoguchi, Lara; Haberer, Jessica; Celum, Connie; Donnell, Deborah; Ngure, Kenneth; Bukusi, Elizabeth; Mugo, Nelly; Asiimwe, Stephen; Odoyo, Josephine; Tindimwebwa, Edna; Bulya, Nulu; Katabira, Elly; Heffron, Renee

    2017-09-13

    People who are asymptomatic and feel healthy, including pregnant women, may be less motivated to initiate ART or achieve high adherence. We assessed whether ART initiation, and viral suppression 6, 12 and 24-months after ART initiation, were lower in HIV-infected members of serodiscordant couples who initiated during pregnancy or with higher CD4 counts. We used data from the Partners Demonstration Project, an open-label study of the delivery of integrated PrEP and ART (at any CD4 count) for HIV prevention among high-risk HIV serodiscordant couples in Kenya and Uganda. Differences in viral suppression (HIV RNA 500 cells/mm3) and during pregnancy were estimated using Poisson regression. Of 865 HIV-infected participants retained after becoming eligible for ART during study follow-up, 95% initiated ART. Viral suppression 24-months after ART initiation was high overall (97%), and comparable among those initiating ART at CD4 counts >500, 351-500 and ≤350 cells/mm3 (96% vs 97% vs 97%; relative risk [RR] 0.98; 95% CI: 0.93-1.03 for CD4 >500 vs <350 and RR 0.99; 95% CI: (0.93-1.06) for CD4 351-500 vs ≤350). Viral suppression was as likely among women initiating ART primarily to prevent perinatal transmission as ART initiation for other reasons (p=0.9 at 6 months and p=0.5 at 12 months). Nearly all HIV-infected partners initiating ART were virally suppressed by 24 months, irrespective of CD4 count or pregnancy status. These findings suggest that people initiating ART at high CD4 counts or due to pregnancy can adhere to ART as well as those starting treatment with symptomatic HIV disease or low CD4 counts.

  16. Importin α5 negatively regulates importin β1-mediated nuclear import of Newcastle disease virus matrix protein and viral replication and pathogenicity in chicken fibroblasts.

    Science.gov (United States)

    Duan, Zhiqiang; Xu, Haixu; Ji, Xinqin; Zhao, Jiafu; Xu, Houqiang; Hu, Yan; Deng, Shanshan; Hu, Shunlin; Liu, Xiufan

    2018-03-13

    The matrix (M) protein of Newcastle disease virus (NDV) is demonstrated to localize in the nucleus via intrinsic nuclear localization signal (NLS), but cellular proteins involved in the nuclear import of NDV M protein and the role of M's nuclear localization in the replication and pathogenicity of NDV remain unclear. In this study, importin β1 was screened to interact with NDV M protein by yeast two-hybrid screening. This interaction was subsequently confirmed by co-immunoprecipitation and pull-down assays. In vitro binding studies indicated that the NLS region of M protein and the amino acids 336-433 of importin β1 that belonged to the RanGTP binding region were important for binding. Importantly, a recombinant virus with M/NLS mutation resulted in a pathotype change of NDV and attenuated viral replication and pathogenicity in chicken fibroblasts and SPF chickens. In agreement with the binding data, nuclear import of NDV M protein in digitonin-permeabilized HeLa cells required both importin β1 and RanGTP. Interestingly, importin α5 was verified to interact with M protein through binding importin β1. However, importin β1 or importin α5 depletion by siRNA resulted in different results, which showed the obviously cytoplasmic or nuclear accumulation of M protein and the remarkably decreased or increased replication ability and pathogenicity of NDV in chicken fibroblasts, respectively. Our findings therefore demonstrate for the first time the nuclear import mechanism of NDV M protein and the negative regulation role of importin α5 in importin β1-mediated nuclear import of M protein and the replication and pathogenicity of a paramyxovirus.

  17. Possible functional co-operation of palindromes hr3 and hr4 in the genome of Cydia pomonella granulovirus affects viral replication capacity.

    Science.gov (United States)

    Elmenofy, Wael H; Jehle, Johannes A

    2015-09-01

    After previous studies had shown that natural transposon insertion between the two homologous regions hr3 and hr4 of the genome of the Mexican (M) strain of Cydia pomonella granulovirus (CpGV-M) resulted in a loss of viral competitiveness, the function of these homologous regions was investigated. A CpGV-based bacmid (CpBAC) was constructed and mutants with deleted hr3 and hr4 palindromes (CpBAChr3/hr4KO) and a construct (CpBAChr3-kan-hr4) with physically separated hr3 and hr4 repeats were generated to investigate their involvement in in vivo replication. Based on median lethal concentration (LC50) and median survival time (ST50) of the mutant viruses vCpBAChr3/hr4KO and vCpBAChr3-kan-hr4 it was found that the infectivity of both mutants for codling moth Cydia pomonella L. (Lep.: Tortricidae) larvae was not influenced compared with the parental virus vCpBAC. Co-infection experiments with vCpBAChr3-kan-hr4 and vCpBAC using different virus ratios revealed that vCpBAChr3-kan-hr4 was efficiently out-competed by vCpBAC during in vivo replication. These findings suggested that the separation of hr3 and hr4 resulted in a replication disadvantage of the mutant similar to the observation made in previous co-infection experiments using the transposon-carrying mutant CpGV-MCp5 and WT CpGV-M. It was concluded that the palindromes hr3 and hr4 may play a non-essential but co-functional role in the replication of CpGV-M.

  18. Contribution of the C-terminal region within the catalytic core domain of HIV-1 integrase to yeast lethality, chromatin binding and viral replication.

    Science.gov (United States)

    Xu, Zaikun; Zheng, Yingfeng; Ao, Zhujun; Clement, Martin; Mouland, Andrew J; Kalpana, Ganjam V; Belhumeur, Pierre; Cohen, Eric A; Yao, Xiaojian

    2008-11-14

    HIV-1 integrase (IN) is a key viral enzymatic molecule required for the integration of the viral cDNA into the genome. Additionally, HIV-1 IN has been shown to play important roles in several other steps during the viral life cycle, including reverse transcription, nuclear import and chromatin targeting. Interestingly, previous studies have demonstrated that the expression of HIV-1 IN induces the lethal phenotype in some strains of Saccharomyces cerevisiae. In this study, we performed mutagenic analyses of the C-terminal region of the catalytic core domain of HIV-1 IN in order to delineate the critical amino acid(s) and/or motif(s) required for the induction of the lethal phenotype in the yeast strain HP16, and to further elucidate the molecular mechanism which causes this phenotype. Our study identified three HIV-1 IN mutants, V165A, A179P and KR186,7AA, located in the C-terminal region of the catalytic core domain of IN that do not induce the lethal phenotype in yeast. Chromatin binding assays in yeast and mammalian cells demonstrated that these IN mutants were impaired for the ability to bind chromatin. Additionally, we determined that while these IN mutants failed to interact with LEDGF/p75, they retained the ability to bind Integrase interactor 1. Furthermore, we observed that VSV-G-pseudotyped HIV-1 containing these IN mutants was unable to replicate in the C8166 T cell line and this defect was partially rescued by complementation with the catalytically inactive D64E IN mutant. Overall, this study demonstrates that three mutations located in the C-terminal region of the catalytic core domain of HIV-1 IN inhibit the IN-induced lethal phenotype in yeast by inhibiting the binding of IN to the host chromatin. These results demonstrate that the C-terminal region of the catalytic core domain of HIV-1 IN is important for binding to host chromatin and is crucial for both viral replication and the promotion of the IN-induced lethal phenotype in yeast.

  19. Contribution of the C-terminal region within the catalytic core domain of HIV-1 integrase to yeast lethality, chromatin binding and viral replication

    Directory of Open Access Journals (Sweden)

    Belhumeur Pierre

    2008-11-01

    Full Text Available Abstract Background HIV-1 integrase (IN is a key viral enzymatic molecule required for the integration of the viral cDNA into the genome. Additionally, HIV-1 IN has been shown to play important roles in several other steps during the viral life cycle, including reverse transcription, nuclear import and chromatin targeting. Interestingly, previous studies have demonstrated that the expression of HIV-1 IN induces the lethal phenotype in some strains of Saccharomyces cerevisiae. In this study, we performed mutagenic analyses of the C-terminal region of the catalytic core domain of HIV-1 IN in order to delineate the critical amino acid(s and/or motif(s required for the induction of the lethal phenotype in the yeast strain HP16, and to further elucidate the molecular mechanism which causes this phenotype. Results Our study identified three HIV-1 IN mutants, V165A, A179P and KR186,7AA, located in the C-terminal region of the catalytic core domain of IN that do not induce the lethal phenotype in yeast. Chromatin binding assays in yeast and mammalian cells demonstrated that these IN mutants were impaired for the ability to bind chromatin. Additionally, we determined that while these IN mutants failed to interact with LEDGF/p75, they retained the ability to bind Integrase interactor 1. Furthermore, we observed that VSV-G-pseudotyped HIV-1 containing these IN mutants was unable to replicate in the C8166 T cell line and this defect was partially rescued by complementation with the catalytically inactive D64E IN mutant. Conclusion Overall, this study demonstrates that three mutations located in the C-terminal region of the catalytic core domain of HIV-1 IN inhibit the IN-induced lethal phenotype in yeast by inhibiting the binding of IN to the host chromatin. These results demonstrate that the C-terminal region of the catalytic core domain of HIV-1 IN is important for binding to host chromatin and is crucial for both viral replication and the promotion of

  20. Noroviruses Co-opt the Function of Host Proteins VAPA and VAPB for Replication via a Phenylalanine-Phenylalanine-Acidic-Tract-Motif Mimic in Nonstructural Viral Protein NS1/2.

    Science.gov (United States)

    McCune, Broc T; Tang, Wei; Lu, Jia; Eaglesham, James B; Thorne, Lucy; Mayer, Anne E; Condiff, Emily; Nice, Timothy J; Goodfellow, Ian; Krezel, Andrzej M; Virgin, Herbert W

    2017-07-11

    The Norovirus genus contains important human pathogens, but the role of host pathways in norovirus replication is largely unknown. Murine noroviruses provide the opportunity to study norovirus replication in cell culture and in small animals. The human norovirus nonstructural protein NS1/2 interacts with the host protein VAMP-associated protein A (VAPA), but the significance of the NS1/2-VAPA interaction is unexplored. Here we report decreased murine norovirus replication in VAPA- and VAPB-deficient cells. We characterized the role of VAPA in detail. VAPA was required for the efficiency of a step(s) in the viral replication cycle after entry of viral RNA into the cytoplasm but before the synthesis of viral minus-sense RNA. The interaction of VAPA with viral NS1/2 proteins is conserved between murine and human noroviruses. Murine norovirus NS1/2 directly bound the major sperm protein (MSP) domain of VAPA through its NS1 domain. Mutations within NS1 that disrupted interaction with VAPA inhibited viral replication. Structural analysis revealed that the viral NS1 domain contains a mimic of the phenylalanine-phenylalanine-acidic-tract (FFAT) motif that enables host proteins to bind to the VAPA MSP domain. The NS1/2-FFAT mimic region interacted with the VAPA-MSP domain in a manner similar to that seen with bona fide host FFAT motifs. Amino acids in the FFAT mimic region of the NS1 domain that are important for viral replication are highly conserved across murine norovirus strains. Thus, VAPA interaction with a norovirus protein that functionally mimics host FFAT motifs is important for murine norovirus replication. IMPORTANCE Human noroviruses are a leading cause of gastroenteritis worldwide, but host factors involved in norovirus replication are incompletely understood. Murine noroviruses have been studied to define mechanisms of norovirus replication. Here we defined the importance of the interaction between the hitherto poorly studied NS1/2 norovirus protein and the

  1. DNA Virus Replication Compartments

    Science.gov (United States)

    Schmid, Melanie; Speiseder, Thomas; Dobner, Thomas

    2014-01-01

    Viruses employ a variety of strategies to usurp and control cellular activities through the orchestrated recruitment of macromolecules to specific cytoplasmic or nuclear compartments. Formation of such specialized virus-induced cellular microenvironments, which have been termed viroplasms, virus factories, or virus replication centers, complexes, or compartments, depends on molecular interactions between viral and cellular factors that participate in viral genome expression and replication and are in some cases associated with sites of virion assembly. These virus-induced compartments function not only to recruit and concentrate factors required for essential steps of the viral replication cycle but also to control the cellular mechanisms of antiviral defense. In this review, we summarize characteristic features of viral replication compartments from different virus families and discuss similarities in the viral and cellular activities that are associated with their assembly and the functions they facilitate for viral replication. PMID:24257611

  2. CD8+ lymphocytes control viral replication in SIVmac239-infected rhesus macaques without decreasing the lifespan of productively infected cells.

    Directory of Open Access Journals (Sweden)

    Nichole R Klatt

    2010-01-01

    Full Text Available While CD8+ T cells are clearly important in controlling virus replication during HIV and SIV infections, the mechanisms underlying this antiviral effect remain poorly understood. In this study, we assessed the in vivo effect of CD8+ lymphocyte depletion on the lifespan of productively infected cells during chronic SIVmac239 infection of rhesus macaques. We treated two groups of animals that were either CD8+ lymphocyte-depleted or controls with antiretroviral therapy, and used mathematical modeling to assess the lifespan of infected cells either in the presence or absence of CD8+ lymphocytes. We found that, in both early (day 57 post-SIV and late (day 177 post-SIV chronic SIV infection, depletion of CD8+ lymphocytes did not result in a measurable increase in the lifespan of either short- or long-lived productively infected cells in vivo. This result indicates that the presence of CD8+ lymphocytes does not result in a noticeably shorter lifespan of productively SIV-infected cells, and thus that direct cell killing is unlikely to be the main mechanism underlying the antiviral effect of CD8+ T cells in SIV-infected macaques with high virus replication.

  3. The impact of transient combination antiretroviral treatment in early HIV infection on viral suppression and immunologic response in later treatment.

    Science.gov (United States)

    Pantazis, Nikos; Touloumi, Giota; Meyer, Laurence; Olson, Ashley; Costagliola, Dominique; Kelleher, Anthony D; Lutsar, Irja; Chaix, Marie-Laure; Fisher, Martin; Moreno, Santiago; Porter, Kholoud

    2016-03-27

    Effects of transient combination antiretroviral treatment (cART) initiated during early HIV infection (EHI) remain unclear. We investigate whether this intervention affects viral suppression and CD4 cell count increase following its reinitiation in chronic infection (CHI). Longitudinal observational study. We identified adult patients from Concerted Action of Seroconversion to AIDS and Death in Europe who seroconverted after 1/1/2000, had a 12 months or less HIV test interval and initiated cART from naive. We classified individuals as 'pretreated in EHI' if treated within 6 months of seroconversion, interrupted for at least 12 weeks, and reinitiated during CHI. Statistical analysis was performed using survival analysis methods and mixed models. Pretreated and initiated in CHI groups comprised 202 and 4263 individuals, with median follow-up after CHI treatment 4.5 and 3 years, respectively. Both groups had similar virologic response and relapse rates (P = 0.585 and P = 0.206) but pretreated individuals restarted treatment with higher baseline CD4 cell count (∼80 cells/μl; P treatment (re)initiation. Assuming common baseline CD4 cell count, differences in CD4 cell count slopes were nonsignificant. Immunovirologic response to CHI treatment was not associated with timing or duration of the transient treatment. Although treatment interruptions are not recommended, stopping cART initiated in EHI does not seem to reduce the chance of a successful outcome of treatment in CHI.

  4. The Polypyrimidine Tract-Binding Protein Affects Coronavirus RNA Accumulation Levels and Relocalizes Viral RNAs to Novel Cytoplasmic Domains Different from Replication-Transcription Sites ▿

    Science.gov (United States)

    Sola, Isabel; Galán, Carmen; Mateos-Gómez, Pedro A.; Palacio, Lorena; Zúñiga, Sonia; Cruz, Jazmina L.; Almazán, Fernando; Enjuanes, Luis

    2011-01-01

    The coronavirus (CoV) discontinuous transcription mechanism is driven by long-distance RNA-RNA interactions between transcription-regulating sequences (TRSs) located at the 5′ terminal leader (TRS-L) and also preceding each mRNA-coding sequence (TRS-B). The contribution of host cell proteins to CoV transcription needs additional information. Polypyrimidine tract-binding protein (PTB) was reproducibly identified in association with positive-sense RNAs of transmissible gastroenteritis coronavirus (TGEV) TRS-L and TRS-B by affinity chromatography and mass spectrometry. A temporal regulation of PTB cytoplasmic levels was observed during infection, with a significant increase from 7 to 16 h postinfection being inversely associated with a decrease in viral replication and transcription. Silencing the expression of PTB with small interfering RNA in two cell lines (Huh7 and HEK 293T) led to a significant increase of up to 4-fold in mRNA levels and virus titer, indicating a negative effect of PTB on CoV RNA accumulation. During CoV infection, PTB relocalized from the nucleus to novel cytoplasmic structures different from replication-transcription sites in which stress granule markers T-cell intracellular antigen-1 (TIA-1) and TIA-1-related protein (TIAR) colocalized. PTB was detected in these modified stress granules in TGEV-infected swine testis cells but not in stress granules induced by oxidative stress. Furthermore, viral genomic and subgenomic RNAs were detected in association with PTB and TIAR. These cytoplasmic ribonucleoprotein complexes might be involved in posttranscriptional regulation of virus gene expression. PMID:21411518

  5. Interference with the production of infectious viral particles and bimodal inhibition of replication are broadly conserved antiviral properties of IFITMs.

    Science.gov (United States)

    Tartour, Kevin; Nguyen, Xuan-Nhi; Appourchaux, Romain; Assil, Sonia; Barateau, Véronique; Bloyet, Louis-Marie; Burlaud Gaillard, Julien; Confort, Marie-Pierre; Escudero-Perez, Beatriz; Gruffat, Henri; Hong, Saw See; Moroso, Marie; Reynard, Olivier; Reynard, Stéphanie; Decembre, Elodie; Ftaich, Najate; Rossi, Axel; Wu, Nannan; Arnaud, Frédérick; Baize, Sylvain; Dreux, Marlène; Gerlier, Denis; Paranhos-Baccala, Glaucia; Volchkov, Viktor; Roingeard, Philippe; Cimarelli, Andrea

    2017-09-01

    IFITMs are broad antiviral factors that block incoming virions in endosomal vesicles, protecting target cells from infection. In the case of HIV-1, we and others reported the existence of an additional antiviral mechanism through which IFITMs lead to the production of virions of reduced infectivity. However, whether this second mechanism of inhibition is unique to HIV or extends to other viruses is currently unknown. To address this question, we have analyzed the susceptibility of a broad spectrum of viruses to the negative imprinting of the virion particles infectivity by IFITMs. The results we have gathered indicate that this second antiviral property of IFITMs extends well beyond HIV and we were able to identify viruses susceptible to the three IFITMs altogether (HIV-1, SIV, MLV, MPMV, VSV, MeV, EBOV, WNV), as well as viruses that displayed a member-specific susceptibility (EBV, DUGV), or were resistant to all IFITMs (HCV, RVFV, MOPV, AAV). The swapping of genetic elements between resistant and susceptible viruses allowed us to point to specificities in the viral mode of assembly, rather than glycoproteins as dominant factors of susceptibility. However, we also show that, contrarily to X4-, R5-tropic HIV-1 envelopes confer resistance against IFITM3, suggesting that viral receptors add an additional layer of complexity in the IFITMs-HIV interplay. Lastly, we show that the overall antiviral effects ascribed to IFITMs during spreading infections, are the result of a bimodal inhibition in which IFITMs act both by protecting target cells from incoming viruses and in driving the production of virions of reduced infectivity. Overall, our study reports for the first time that the negative imprinting of the virion particles infectivity is a conserved antiviral property of IFITMs and establishes IFITMs as a paradigm of restriction factor capable of interfering with two distinct phases of a virus life cycle.

  6. Patterns of HIV service use and HIV viral suppression among patients treated in an academic infectious diseases clinic in North Carolina.

    Science.gov (United States)

    Palma, Anton; Lounsbury, David W; Messer, Lynne; Quinlivan, Evelyn Byrd

    2015-04-01

    Irregular participation in HIV medical care hinders HIV RNA suppression and impacts health among people living with HIV. Cluster analysis of clinical data from 1,748 patients attending a large academic medical center yielded three HIV service usage patterns, namely: 'engaged in care', 'sporadic care', and 'frequent use'. Patients 'engaged in care' exhibited most consistent retention (on average, >88 % of each patient's observation years had ≥2 visits 90 days apart), annualized visit use (2.9 mean visits/year) and viral suppression (>73 % HIV RNA tests use (1.7 visits/year) and viral suppression (56 % use' (5.2 visits/year) had more inpatient and emergency visits. Female, out-of-state residence, low attendance during the first observation year and detectable first-observed HIV RNA were early predictors of subsequent service usage. Patients 'engaged in care' were more likely to have HIV RNA <400 than those receiving sporadic care. Results confirm earlier findings that under-utilization of services predicts poorer viral suppression and health outcomes and support recommendations for 2-3 visits/year.

  7. Assessing Zika virus replication and the development of Zika-specific antibodies after a mid-gestation viral challenge in guinea pigs.

    Science.gov (United States)

    Bierle, Craig J; Fernández-Alarcón, Claudia; Hernandez-Alvarado, Nelmary; Zabeli, Jason C; Janus, Bradley C; Putri, Dira S; Schleiss, Mark R

    2017-01-01

    Primary Zika virus (ZIKV) infections that occur during pregnancy can cause spontaneous abortion and profoundly disrupt fetal development. While the full range of developmental abnormalities associated with congenital Zika syndrome is not yet known, severe cases of the syndrome can present with microcephaly, extensive neurologic and ocular damage, and pronounced joint malformations. Animal models that accurately recapitulate congenital Zika syndrome are urgently needed for vaccine development and for the study of ZIKV pathogenesis. As guinea pigs have successfully been used to model transplacental infections by cytomegalovirus, syphilis, and Listeria monocytogenes, we sought to test whether ZIKV could productively infect guinea pigs and whether viral transmission with attendant fetal pathology would occur after a mid-gestation viral challenge. We found that guinea pig cells supported ZIKV replication in vitro. Experimental infection of non-pregnant animals did not result in overt disease but low-level, detectable viremia was observed. When pregnant guinea pigs were challenged with ZIKV at between 18 and 21 days gestational age, ZIKV was not detected in maternal or pup blood, plasma, or tissues and no significant differences in maternal weight gain or pup size were observed following challenge. Nonetheless, a robust antibody response against ZIKV was detected in both the pups and dams. These results suggest that, while guinea pigs can model aspects of the immune response to ZIKV infection during pregnancy, naturally circulating ZIKV strains are not pathogenic during the pregnancy of immunocompetent guinea pigs and do not interfere with normal pup development.

  8. Assessing Zika virus replication and the development of Zika-specific antibodies after a mid-gestation viral challenge in guinea pigs.

    Directory of Open Access Journals (Sweden)

    Craig J Bierle

    Full Text Available Primary Zika virus (ZIKV infections that occur during pregnancy can cause spontaneous abortion and profoundly disrupt fetal development. While the full range of developmental abnormalities associated with congenital Zika syndrome is not yet known, severe cases of the syndrome can present with microcephaly, extensive neurologic and ocular damage, and pronounced joint malformations. Animal models that accurately recapitulate congenital Zika syndrome are urgently needed for vaccine development and for the study of ZIKV pathogenesis. As guinea pigs have successfully been used to model transplacental infections by cytomegalovirus, syphilis, and Listeria monocytogenes, we sought to test whether ZIKV could productively infect guinea pigs and whether viral transmission with attendant fetal pathology would occur after a mid-gestation viral challenge. We found that guinea pig cells supported ZIKV replication in vitro. Experimental infection of non-pregnant animals did not result in overt disease but low-level, detectable viremia was observed. When pregnant guinea pigs were challenged with ZIKV at between 18 and 21 days gestational age, ZIKV was not detected in maternal or pup blood, plasma, or tissues and no significant differences in maternal weight gain or pup size were observed following challenge. Nonetheless, a robust antibody response against ZIKV was detected in both the pups and dams. These results suggest that, while guinea pigs can model aspects of the immune response to ZIKV infection during pregnancy, naturally circulating ZIKV strains are not pathogenic during the pregnancy of immunocompetent guinea pigs and do not interfere with normal pup development.

  9. Ocean acidification and viral replication cycles: Frequency of lytically infected and lysogenic cells during a mesocosm experiment in the NW Mediterranean Sea

    Science.gov (United States)

    Tsiola, Anastasia; Pitta, Paraskevi; Giannakourou, Antonia; Bourdin, Guillaume; Marro, Sophie; Maugendre, Laure; Pedrotti, Maria Luiza; Gazeau, Frédéric

    2017-02-01

    The frequency of lytically infected and lysogenic cells (FLIC and FLC, respectively) was estimated during an in situ mesocosm experiment studying the impact of ocean acidification on the plankton community of a low nutrient low chlorophyll (LNLC) system in the north-western Mediterranean Sea (Bay of Villefranche, France) in February/March 2013. No direct effect of elevated partial pressure of CO2 (pCO2) on viral replication cycles could be detected. FLC variability was negatively correlated to heterotrophic bacterial and net community production as well as the ambient bacterial abundance, confirming that lysogeny is a prevailing life strategy under unfavourable-for-the-hosts conditions. Further, the phytoplankton community, assessed by chlorophyll a concentration and the release of >0.4 μm transparent exopolymeric particles, was correlated with the occurrence of lysogeny, indicating a possible link between photosynthetic processes and bacterial growth. Higher FLC was found occasionally at the highest pCO2-treated mesocosm in parallel to subtle differences in the phytoplankton community. This observation suggests that elevated pCO2 could lead to short-term alterations in lysogenic dynamics coupled to phytoplankton-derived processes. Correlation of FLIC with any environmental parameter could have been obscured by the sampling time or the synchronization of lysis to microbial processes not assessed in this experiment. Furthermore, alterations in microbial and viral assemblage composition and gene expression could be a confounding factor. Viral-induced modifications in organic matter flow affect bacterial growth and could interact with ocean acidification with unpredictable ecological consequences.

  10. Stable expression and replication of hepatitis B virus genome in an integrated state in a human hepatoma cell line transfected with the cloned viral DNA

    International Nuclear Information System (INIS)

    Tsurimoto, T.; Fujiyama, A.; Matsubara, K.

    1987-01-01

    A human hepatocellular carcinoma cell line (Huh6-c15) was transfected with a recombinant DNA molecule that consists of tandemly arranged hepatitis B virus (HBV) genome and a neomycin-resistant gene. One clone resistant to G-418 produces and releases surface antigen and e antigen into medium at a high level and accumulates core particles intracellularly. This clone has a chromosomally integrated set of the original recombinant DNA and produces a 3.5-kilobase transcript corresponding to the pregenome RNA as well as HBV DNAs in an extrachromosomal form. Most of these DNAs were in single-stranded or partially double-stranded form and were packaged in the intracellular core particles. In the medium, particles were detected that contained HBV DNA and were morphologically indistinguishable from Dane particles. These results demonstrate that the HBV genome in an integrated state acted as a template for viral gene expression and replication. The cells were maintained for more than 6 months without losing the ability to produce the extrachromosomal HBV DNA and Dane-like particles. Thus, the cells can be used as a model system for analyses of gene expression and DNA replication of HBV in human hepatocytes

  11. Stable expression and replication of hepatitis B virus genome in an integrated state in a human hepatoma cell line transfected with the cloned viral DNA.

    Science.gov (United States)

    Tsurimoto, T; Fujiyama, A; Matsubara, K

    1987-01-01

    A human hepatocellular carcinoma cell line (Huh6-c15) was transfected with a recombinant DNA molecule that consists of tandemly arranged hepatitis B virus (HBV) genome and a neomycin-resistant gene. One clone resistant to G-418 produces and releases surface antigen and e antigen into medium at a high level and accumulates core particles intracellularly. This clone has a chromosomally integrated set of the original recombinant DNA and produces a 3.5-kilobase transcript corresponding to the pregenome RNA as well as HBV DNAs in an extrachromosomal form. Most of these DNAs were in single-stranded or partially double-stranded form and were packaged in the intracellular core particles. In the medium, particles were detected that contained HBV DNA and were morphologically indistinguishable from Dane particles. These results demonstrate that the HBV genome in an integrated state acted as a template for viral gene expression and replication. The cells were maintained for more than 6 months without losing the ability to produce the extrachromosomal HBV DNA and Dane-like particles. Thus, the cells can be used as a model system for analyses of gene expression and DNA replication of HBV in human hepatocytes.

  12. Cyclin-dependent kinase suppression by WEE1 kinase protects the genome through control of replication initiation and nucleotide consumption

    DEFF Research Database (Denmark)

    Beck, Halfdan; Nähse-Kumpf, Viola; Larsen, Marie Sofie Yoo

    2012-01-01

    Activation of oncogenes or inhibition of WEE1 kinase deregulates Cyclin-dependent kinase (CDK) activity and leads to replication stress, however, the underlying mechanism is not understood. We now show that elevation of CDK activity by inhibiting WEE1 kinase rapidly increases initiation of replic...... that deregulated CDK activity, such as that occurring following inhibition of WEE1 kinase or activation of oncogenes, induces replication stress and loss of genomic integrity through increased firing of replication origins and subsequent nucleotide shortage.......Activation of oncogenes or inhibition of WEE1 kinase deregulates Cyclin-dependent kinase (CDK) activity and leads to replication stress, however, the underlying mechanism is not understood. We now show that elevation of CDK activity by inhibiting WEE1 kinase rapidly increases initiation...

  13. Hibiscus chlorotic ringspot virus coat protein is essential for cell-to-cell and long-distance movement but not for viral RNA replication.

    Directory of Open Access Journals (Sweden)

    Shengniao Niu

    Full Text Available Hibiscus chlorotic ringspot virus (HCRSV is a member of the genus Carmovirus in the family Tombusviridae. In order to study its coat protein (CP functions on virus replication and movement in kenaf (Hibiscus cannabinus L., two HCRSV mutants, designated as p2590 (A to G in which the first start codon ATG was replaced with GTG and p2776 (C to G in which proline 63 was replaced with alanine, were constructed. In vitro transcripts of p2590 (A to G were able to replicate to a similar level as wild type without CP expression in kenaf protoplasts. However, its cell-to-cell movement was not detected in the inoculated kenaf cotyledons. Structurally the proline 63 in subunit C acts as a kink for β-annulus formation during virion assembly. Progeny of transcripts derived from p2776 (C to G was able to move from cell-to-cell in inoculated cotyledons but its long-distance movement was not detected. Virions were not observed in partially purified mutant virus samples isolated from 2776 (C to G inoculated cotyledons. Removal of the N-terminal 77 amino acids of HCRSV CP by trypsin digestion of purified wild type HCRSV virions resulted in only T = 1 empty virus-like particles. Taken together, HCRSV CP is dispensable for viral RNA replication but essential for cell-to-cell movement, and virion is required for the virus systemic movement. The proline 63 is crucial for HCRSV virion assembly in kenaf plants and the N-terminal 77 amino acids including the β-annulus domain is required in T = 3 assembly in vitro.

  14. Hibiscus Chlorotic Ringspot Virus Coat Protein Is Essential for Cell-to-Cell and Long-Distance Movement but Not for Viral RNA Replication

    Science.gov (United States)

    Niu, Shengniao; Gil-Salas, Francisco M.; Tewary, Sunil Kumar; Samales, Ashwin Kuppusamy; Johnson, John; Swaminathan, Kunchithapadam; Wong, Sek-Man

    2014-01-01

    Hibiscus chlorotic ringspot virus (HCRSV) is a member of the genus Carmovirus in the family Tombusviridae. In order to study its coat protein (CP) functions on virus replication and movement in kenaf (Hibiscus cannabinus L.), two HCRSV mutants, designated as p2590 (A to G) in which the first start codon ATG was replaced with GTG and p2776 (C to G) in which proline 63 was replaced with alanine, were constructed. In vitro transcripts of p2590 (A to G) were able to replicate to a similar level as wild type without CP expression in kenaf protoplasts. However, its cell-to-cell movement was not detected in the inoculated kenaf cotyledons. Structurally the proline 63 in subunit C acts as a kink for β-annulus formation during virion assembly. Progeny of transcripts derived from p2776 (C to G) was able to move from cell-to-cell in inoculated cotyledons but its long-distance movement was not detected. Virions were not observed in partially purified mutant virus samples isolated from 2776 (C to G) inoculated cotyledons. Removal of the N-terminal 77 amino acids of HCRSV CP by trypsin digestion of purified wild type HCRSV virions resulted in only T = 1 empty virus-like particles. Taken together, HCRSV CP is dispensable for viral RNA replication but essential for cell-to-cell movement, and virion is required for the virus systemic movement. The proline 63 is crucial for HCRSV virion assembly in kenaf plants and the N-terminal 77 amino acids including the β-annulus domain is required in T = 3 assembly in vitro. PMID:25402344

  15. Infection with equine infectious anemia virus vaccine strain EIAVDLV121 causes no visible histopathological lesions in target organs in association with restricted viral replication and unique cytokine response.

    Science.gov (United States)

    Liu, Qiang; Ma, Jian; Wang, Xue-Feng; Xiao, Fei; Li, Li-Jia; Zhang, Jiao-Er; Lin, Yue-Zhi; Du, Cheng; He, Xi-Jun; Wang, Xiaojun; Zhou, Jian-Hua

    2016-02-01

    The live equine infectious anemia virus (EIAV) vaccine strain EIAVDLV121 was developed by in vitro attenuation of a virulent strain, EIAVLN40, in the 1970s, and it has been demonstrated to induce protective immunity under laboratory and natural EIAV infection conditions. The detailed biological features of this attenuated virus remain to be further investigated. Experimental inoculation with EIAVDLV121 did not result in clinical symptoms even with immunosuppressive treatment in our previous studies. Here, we further investigated whether the replication of the vaccine strain EIAVDLV121 in experimentally infected horses causes histopathological lesions to develop in the targeted organs. Both the lungs and the spleen have been demonstrated to support EIAV replication. By evaluating the gross macroscopic and histological changes, we found that EIAVDLV121 did not cause detectable histopathological lesions and that it replicated several hundred times more slowly than its parental virulent strain, EIAVLN40, in tissues. Immunochemical assays of these tissues indicated that the primary target cells of EIAVDLV121 were monocytes/macrophages, but that EIAVLN40 also infected alveolar epithelial cells and vascular endothelial cells. In addition, both of these viral strains promoted the up- and down-regulation of the expression of various cytokines and chemokines, implicating the potential involvement of these cellular factors in the pathological outcomes of EIAV infection and host immune responses. Taken together, these results demonstrate that the EIAV vaccine strain does not cause obvious histopathological lesions or clinical symptoms and that it induces a unique cytokine response profile. These features are considered essential for EIAVDLV121 to function as an effective live vaccine. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Small RNAs targeting the 5' end of the viral polymerase gene segments specifically interfere with influenza type A virus replication.

    Science.gov (United States)

    Martelli, Francesco; Salata, Cristiano; Calistri, Arianna; Parolin, Cristina; Azzi, Alberta; Palù, Giorgio; Giannecchini, Simone

    2015-09-20

    Human and avian influenza A viruses, associated with seasonal epidemics and occasionally with pandemics, have a high impact on public health. The development of new antivirals to counteract the emergence of drug resistant influenza virus variants is a main concern. The aim of this study was to develop systems for the efficient and stable expression of small therapeutic RNAs into influenza virus infected cells in order to get further insights on the efficacy of nucleic acid-based antiviral strategies. To this end, lentiviral vectors expressing either microRNAs or antisense-RNAs targeting the 5' end of the PA, PB1 and PB2 influenza virus genomic sequences were generated. Derivative recombinant lentiviral particles were employed to transduce the influenza virus highly susceptible human alveolar basal epithelial A549 cells. The expression of both RNA molecules led to a reduction up to 3 logs of the viral titer when transduced A549 cells were challenged with different human and avian subtypes of influenza type A virus. Importantly, no inhibition of influenza type B virus was observed. Overall our data support the development of nucleic acid-based antiviral strategies to control human and avian influenza A virus infection. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Comparative analysis of seven viral nuclear export signals (NESs reveals the crucial role of nuclear export mediated by the third NES consensus sequence of nucleoprotein (NP in influenza A virus replication.

    Directory of Open Access Journals (Sweden)

    Nopporn Chutiwitoonchai

    Full Text Available The assembly of influenza virus progeny virions requires machinery that exports viral genomic ribonucleoproteins from the cell nucleus. Currently, seven nuclear export signal (NES consensus sequences have been identified in different viral proteins, including NS1, NS2, M1, and NP. The present study examined the roles of viral NES consensus sequences and their significance in terms of viral replication and nuclear export. Mutation of the NP-NES3 consensus sequence resulted in a failure to rescue viruses using a reverse genetics approach, whereas mutation of the NS2-NES1 and NS2-NES2 sequences led to a strong reduction in viral replication kinetics compared with the wild-type sequence. While the viral replication kinetics for other NES mutant viruses were also lower than those of the wild-type, the difference was not so marked. Immunofluorescence analysis after transient expression of NP-NES3, NS2-NES1, or NS2-NES2 proteins in host cells showed that they accumulated in the cell nucleus. These results suggest that the NP-NES3 consensus sequence is mostly required for viral replication. Therefore, each of the hydrophobic (Φ residues within this NES consensus sequence (Φ1, Φ2, Φ3, or Φ4 was mutated, and its viral replication and nuclear export function were analyzed. No viruses harboring NP-NES3 Φ2 or Φ3 mutants could be rescued. Consistent with this, the NP-NES3 Φ2 and Φ3 mutants showed reduced binding affinity with CRM1 in a pull-down assay, and both accumulated in the cell nucleus. Indeed, a nuclear export assay revealed that these mutant proteins showed lower nuclear export activity than the wild-type protein. Moreover, the Φ2 and Φ3 residues (along with other Φ residues within the NP-NES3 consensus were highly conserved among different influenza A viruses, including human, avian, and swine. Taken together, these results suggest that the Φ2 and Φ3 residues within the NP-NES3 protein are important for its nuclear export function

  18. A marginal structural model to estimate the causal effect of antidepressant medication treatment on viral suppression among homeless and marginally housed persons with HIV.

    Science.gov (United States)

    Tsai, Alexander C; Weiser, Sheri D; Petersen, Maya L; Ragland, Kathleen; Kushel, Margot B; Bangsberg, David R

    2010-12-01

    Depression strongly predicts nonadherence to human immunodeficiency virus (HIV) antiretroviral therapy, and adherence is essential to maintaining viral suppression. This suggests that pharmacologic treatment of depression may improve virologic outcomes. However, previous longitudinal observational analyses have inadequately adjusted for time-varying confounding by depression severity, which could yield biased estimates of treatment effect. Application of marginal structural modeling to longitudinal observation data can, under certain assumptions, approximate the findings of a randomized controlled trial. To determine whether antidepressant medication treatment increases the probability of HIV viral suppression. Community-based prospective cohort study with assessments conducted every 3 months. Community-based research field site in San Francisco, California. One hundred fifty-eight homeless and marginally housed persons with HIV who met baseline immunologic (CD4+ T-lymphocyte count, 13) inclusion criteria, observed from April 2002 through August 2007. Probability of achieving viral suppression to less than 50 copies/mL. Secondary outcomes of interest were probability of being on an antiretroviral therapy regimen, 7-day self-reported percentage adherence to antiretroviral therapy, and probability of reporting complete (100%) adherence. Marginal structural models estimated a 2.03 greater odds of achieving viral suppression (95% confidence interval [CI], 1.15-3.58; P = .02) resulting from antidepressant medication treatment. In addition, antidepressant medication use increased the probability of antiretroviral uptake (weighted odds ratio, 3.87; 95% CI, 1.98-7.58; P effect is likely attributable to improved adherence to a continuum of HIV care, including increased uptake and adherence to antiretroviral therapy.

  19. Assessing the HIV Care Continuum in Latin America: progress in clinical retention, cART use and viral suppression

    Science.gov (United States)

    Rebeiro, Peter F; Cesar, Carina; Shepherd, Bryan E; De Boni, Raquel B; Cortés, Claudia P; Rodriguez, Fernanda; Belaunzarán-Zamudio, Pablo; Pape, Jean W; Padgett, Denis; Hoces, Daniel; McGowan, Catherine C; Cahn, Pedro

    2016-01-01

    Introduction We assessed trends in HIV Care Continuum outcomes associated with delayed disease progression and reduced transmission within a large Latin American cohort over a decade: clinical retention, combination antiretroviral therapy (cART) use and viral suppression (VS). Methods Adults from Caribbean, Central and South America network for HIV epidemiology clinical cohorts in seven countries contributed data between 2003 and 2012. Retention was defined as two or more HIV care visits annually, >90 days apart. cART was defined as prescription of three or more antiretroviral agents annually. VS was defined as HIV-1 RNA <200 copies/mL at last measurement annually. cART and VS denominators were subjects with at least one visit annually. Multivariable modified Poisson regression was used to assess temporal trends and examine associations between age, sex, HIV transmission mode, cohort, calendar year and time in care. Results Among 18,799 individuals in retention analyses, 14,380 in cART analyses and 13,330 in VS analyses, differences existed between those meeting indicator definitions versus those not by most characteristics. Retention, cART and VS significantly improved from 2003 to 2012 (63 to 77%, 74 to 91% and 53 to 82%, respectively; p<0.05, each). Female sex (risk ratio (RR)=0.97 vs. males) and injection drug use as HIV transmission mode (RR=0.83 vs. male sexual contact with males (MSM)) were significantly associated with lower retention, but unrelated with cART or VS. MSM (RR=0.96) significantly decreased the probability of cART compared with heterosexual transmission. Conclusions HIV Care Continuum outcomes improved over time in Latin America, though disparities for vulnerable groups remain. Efforts must be made to increase retention, cART and VS, while engaging in additional research to sustain progress in these settings. PMID:27065108

  20. Improving ART programme retention and viral suppression are key to maximising impact of treatment as prevention - a modelling study.

    Science.gov (United States)

    McCreesh, Nicky; Andrianakis, Ioannis; Nsubuga, Rebecca N; Strong, Mark; Vernon, Ian; McKinley, Trevelyan J; Oakley, Jeremy E; Goldstein, Michael; Hayes, Richard; White, Richard G

    2017-08-09

    UNAIDS calls for fewer than 500,000 new HIV infections/year by 2020, with treatment-as-prevention being a key part of their strategy for achieving the target. A better understanding of the contribution to transmission of people at different stages of the care pathway can help focus intervention services at populations where they may have the greatest effect. We investigate this using Uganda as a case study. An individual-based HIV/ART model was fitted using history matching. 100 model fits were generated to account for uncertainties in sexual behaviour, HIV epidemiology, and ART coverage up to 2015 in Uganda. A number of different ART scale-up intervention scenarios were simulated between 2016 and 2030. The incidence and proportion of transmission over time from people with primary infection, post-primary ART-naïve infection, and people currently or previously on ART was calculated. In all scenarios, the proportion of transmission by ART-naïve people decreases, from 70% (61%-79%) in 2015 to between 23% (15%-40%) and 47% (35%-61%) in 2030. The proportion of transmission by people on ART increases from 7.8% (3.5%-13%) to between 14% (7.0%-24%) and 38% (21%-55%). The proportion of transmission by ART dropouts increases from 22% (15%-33%) to between 31% (23%-43%) and 56% (43%-70%). People who are currently or previously on ART are likely to play an increasingly large role in transmission as ART coverage increases in Uganda. Improving retention on ART, and ensuring that people on ART remain virally suppressed, will be key in reducing HIV incidence in Uganda.

  1. Interferon-inducible ribonuclease ISG20 inhibits hepatitis B virus replication through directly binding to the epsilon stem-loop structure of viral RNA.

    Directory of Open Access Journals (Sweden)

    Yuanjie Liu

    2017-04-01

    Full Text Available Hepatitis B virus (HBV replicates its DNA genome through reverse transcription of a viral RNA pregenome. We report herein that the interferon (IFN stimulated exoribonuclease gene of 20 KD (ISG20 inhibits HBV replication through degradation of HBV RNA. ISG20 expression was observed at basal level and was highly upregulated upon IFN treatment in hepatocytes, and knock down of ISG20 resulted in elevation of HBV replication and attenuation of IFN-mediated antiviral effect. The sequence element conferring the susceptibility of HBV RNA to ISG20-mediated RNA degradation was mapped at the HBV RNA terminal redundant region containing epsilon (ε stem-loop. Furthermore, ISG20-induced HBV RNA degradation relies on its ribonuclease activity, as the enzymatic inactive form ISG20D94G was unable to promote HBV RNA decay. Interestingly, ISG20D94G retained antiviral activity against HBV DNA replication by preventing pgRNA encapsidation, resulting from a consequence of ISG20-ε interaction. This interaction was further characterized by in vitro electrophoretic mobility shift assay (EMSA and ISG20 was able to bind HBV ε directly in absence of any other cellular proteins, indicating a direct ε RNA binding capability of ISG20; however, cofactor(s may be required for ISG20 to efficiently degrade ε. In addition, the lower stem portion of ε is the major ISG20 binding site, and the removal of 4 base pairs from the bottom portion of ε abrogated the sensitivity of HBV RNA to ISG20, suggesting that the specificity of ISG20-ε interaction relies on both RNA structure and sequence. Furthermore, the C-terminal Exonuclease III (ExoIII domain of ISG20 was determined to be responsible for interacting with ε, as the deletion of ExoIII abolished in vitro ISG20-ε binding and intracellular HBV RNA degradation. Taken together, our study sheds light on the underlying mechanisms of IFN-mediated HBV inhibition and the antiviral mechanism of ISG20 in general.

  2. Herpes Simplex Virus 1 Mutant with Point Mutations in UL39 Is Impaired for Acute Viral Replication in Mice, Establishment of Latency, and Explant-Induced Reactivation.

    Science.gov (United States)

    Mostafa, Heba H; Thompson, Thornton W; Konen, Adam J; Haenchen, Steve D; Hilliard, Joshua G; Macdonald, Stuart J; Morrison, Lynda A; Davido, David J

    2018-04-01

    In the process of generating herpes simplex virus 1 (HSV-1) mutations in the viral regulatory gene encoding infected cell protein 0 (ICP0), we isolated a viral mutant, termed KOS-NA, that was severely impaired for acute replication in the eyes and trigeminal ganglia (TG) of mice, defective in establishing a latent infection, and reactivated poorly from explanted TG. To identify the secondary mutation(s) responsible for the impaired phenotypes of this mutant, we sequenced the KOS-NA genome and noted that it contained two nonsynonymous mutations in UL39 , which encodes the large subunit of ribonucleotide reductase, ICP6. These mutations resulted in lysine-to-proline (residue 393) and arginine-to-histidine (residue 950) substitutions in ICP6. To determine whether alteration of these amino acids was responsible for the KOS-NA phenotypes in vivo , we recombined the wild-type UL39 gene into the KOS-NA genome and rescued its acute replication phenotypes in mice. To further establish the role of UL39 in KOS-NA's decreased pathogenicity, the UL39 mutations were recombined into HSV-1 (generating UL39 mut ), and this mutant virus showed reduced ocular and TG replication in mice comparable to that of KOS-NA. Interestingly, ICP6 protein levels were reduced in KOS-NA-infected cells relative to the wild-type protein. Moreover, we observed that KOS-NA does not counteract caspase 8-induced apoptosis, unlike wild-type strain KOS. Based on alignment studies with other HSV-1 ICP6 homologs, our data suggest that amino acid 950 of ICP6 likely plays an important role in ICP6 accumulation and inhibition of apoptosis, consequently impairing HSV-1 pathogenesis in a mouse model of HSV-1 infection. IMPORTANCE HSV-1 is a major human pathogen that infects ∼80% of the human population and can be life threatening to infected neonates or immunocompromised individuals. Effective therapies for treatment of recurrent HSV-1 infections are limited, which emphasizes a critical need to understand in

  3. A mutation in the DNA polymerase accessory factor of herpes simplex virus 1 restores viral DNA replication in the presence of raltegravir.

    Science.gov (United States)

    Zhou, Bin; Yang, Kui; Wills, Elizabeth; Tang, Liang; Baines, Joel D

    2014-10-01

    Previous reports showed that raltegravir, a recently approved antiviral compound that targets HIV integrase, can inhibit the nuclease function of human cytomegalovirus (HCMV terminase) in vitro. In this study, subtoxic levels of raltegravir were shown to inhibit the replication of four different herpesviruses, herpes simplex virus 1 (HSV-1), HSV-2, HCMV, and mouse cytomegalovirus, by 30- to 700-fold, depending on the dose and the virus tested. Southern blotting and quantitative PCR revealed that raltegravir inhibits DNA replication of HSV-1 rather than cleavage of viral DNA. A raltegravir-resistant HSV-1 mutant was generated by repeated passage in the presence of 200 μM raltegravir. The genomic sequence of the resistant virus, designated clone 7, contained mutations in 16 open reading frames. Of these, the mutations F198S in unique long region 15 (UL15; encoding the large terminase subunit), A374V in UL32 (required for DNA cleavage and packaging), V296I in UL42 (encoding the DNA polymerase accessory factor), and A224S in UL54 (encoding ICP27, an important transcriptional regulator) were introduced independently into the wild-type HSV-1(F) genome, and the recombinant viruses were tested for raltegravir resistance. Viruses bearing both the UL15 and UL32 mutations inserted within the genome of the UL42 mutant were also tested. While the UL15, UL32, and UL54 mutant viruses were fully susceptible to raltegravir, any virus bearing the UL42 mutation was as resistant to raltegravir as clone 7. Overall, these results suggest that raltegravir may be a valuable therapeutic agent against herpesviruses and the antiviral activity targets the DNA polymerase accessory factor rather than the nuclease activity of the terminase. This paper shows that raltegravir, the antiretrovirus drug targeting integrase, is effective against various herpesviruses. Drug resistance mapped to the herpesvirus DNA polymerase accessory factor, which was an unexpected finding. Copyright © 2014

  4. Optimizing prevention of HIV mother to child transmission: Duration of antiretroviral therapy and viral suppression at delivery among pregnant Malawian women.

    Science.gov (United States)

    Chagomerana, Maganizo B; Miller, William C; Tang, Jennifer H; Hoffman, Irving F; Mthiko, Bryan C; Phulusa, Jacob; John, Mathias; Jumbe, Allan; Hosseinipour, Mina C

    2018-01-01

    Effective antiretroviral therapy during pregnancy minimizes the risk of vertical HIV transmission. Some women present late in their pregnancy for first antenatal visit; whether these women achieve viral suppression by delivery and how suppression varies with time on ART is unclear. We conducted a prospective cohort study of HIV-infected pregnant women initiating antiretroviral therapy for the first time at Bwaila Hospital in Lilongwe, Malawi from June 2015 to November 2016. Multivariable Poisson models with robust variance estimators were used to estimate risk ratios (RR) and 95% confidence intervals (CI) of the association between duration of ART and both viral load (VL) ≥1000 copies/ml and VL ≥40 copies/ml at delivery. Of the 252 women who had viral load testing at delivery, 40 (16%) and 78 (31%) had VL ≥1000 copies/ml and VL ≥40 copies/ml, respectively. The proportion of women with poor adherence to ART was higher among women who were on ART for ≤12 weeks (9/50 = 18.0%) than among those who were on ART for 13-35 weeks (18/194 = 9.3%). Compared to women who were on ART for ≤12 weeks, women who were on ART for 13-20 weeks (RR = 0.52; 95% CI: 0.36-0.74) or 21-35 weeks (RR = 0.26; 95% CI: 0.14-0.48) had a lower risk of VL ≥40 copies/ml at delivery. Similar comparisons for VL ≥1000 copies/ml at delivery showed decrease in risk although not significant for those on ART 13-20 weeks. Longer duration of ART during pregnancy was associated with suppressed viral load at delivery. Early ANC attendance in pregnancy to facilitate prompt ART initiation for HIV-positive women is essential in the effort to eliminate HIV vertical transmission.

  5. Expression of an IRF-3 fusion protein and mouse estrogen receptor, inhibits hepatitis C viral replication in RIG-I-deficient Huh 7.5 cells

    Directory of Open Access Journals (Sweden)

    Liu Chen

    2011-09-01

    Full Text Available Abstract Interferon Regulatory Factor-3 (IRF-3 plays a central role in the induction of interferon (IFN production and succeeding interferon-stimulated genes (ISG expression en route for restraining hepatitis C virus (HCV infection. Here, we established a stable Huh7.5-IRF3ER cell line expressing a fusion protein of IRF-3 and mouse estrogen receptor (ER to examine IFN production and anti-HCV effects of IRF-3 in retinoic acid inducible-gene-I (RIG-I deficient Huh 7.5 cells. Homodimerization of the IRF-3ER fusion protein was detected by Western blotting after treatment with the estrogen receptor agonist 4-hydrotamoxifen (4-HT in Huh7.5-IRF3ER cells. Expression of IFN-α, IFN-β, and their inhibitory effects on HCV replication were demonstrated by real-time polymerase chain reaction (PCR. Peak expression of IFN-α and IFN-β was achieved 24-hours post 4-HT treatment, coinciding with the appearance of phosphorylated signal transducer and activator of transcription (STAT proteins. Additionally, HCV viral replication declined in time-dependent fashion. In previous studies, a novel IFN-mediated pathway regulating expression of 1-8U and heterogeneous nuclear ribonucleoprotein M (hnRNP M inhibited HCV internal ribosomal entry site (IRES-dependent translation. When expression of ISGs such as 1-8U and hnRNP M were measured in 4-HT-treated Huh7.5-IRF3ER cells, both genes were positively regulated by activation of the IRF-3ER fusion protein. In conclusion, the anti-HCV effects of IRF-3ER homodimerization inhibited HCV RNA replication as well as HCV IRES-dependent translation in Huh7.5-IRF3ER cells. The results of this study indicate that IRF-3ER homodimerization is a key step to restore IFN expression in Huh7.5-IRF3ER cells and in achieving its anti-HCV effects.

  6. Ultrastructural Characterization of Zika Virus Replication Factories

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    Mirko Cortese

    2017-02-01

    Full Text Available Summary: A global concern has emerged with the pandemic spread of Zika virus (ZIKV infections that can cause severe neurological symptoms in adults and newborns. ZIKV is a positive-strand RNA virus replicating in virus-induced membranous replication factories (RFs. Here we used various imaging techniques to investigate the ultrastructural details of ZIKV RFs and their relationship with host cell organelles. Analyses of human hepatic cells and neural progenitor cells infected with ZIKV revealed endoplasmic reticulum (ER membrane invaginations containing pore-like openings toward the cytosol, reminiscent to RFs in Dengue virus-infected cells. Both the MR766 African strain and the H/PF/2013 Asian strain, the latter linked to neurological diseases, induce RFs of similar architecture. Importantly, ZIKV infection causes a drastic reorganization of microtubules and intermediate filaments forming cage-like structures surrounding the viral RF. Consistently, ZIKV replication is suppressed by cytoskeleton-targeting drugs. Thus, ZIKV RFs are tightly linked to rearrangements of the host cell cytoskeleton. : Cortese et al. show that ZIKV infection in both human hepatoma and neuronal progenitor cells induces drastic structural modification of the cellular architecture. Microtubules and intermediate filaments surround the viral replication factory composed of vesicles corresponding to ER membrane invagination toward the ER lumen. Importantly, alteration of microtubule flexibility impairs ZIKV replication. Keywords: Zika virus, flavivirus, human neural progenitor cells, replication factories, replication organelles, microtubules, intermediate filaments, electron microscopy, electron tomography, live-cell imaging

  7. The intrinsically disordered N-terminal arm of the brome mosaic virus coat protein specifically recognizes the RNA motif that directs the initiation of viral RNA replication.

    Science.gov (United States)

    Jacobs, Alexander; Hoover, Haley; Smith, Edward; Clemmer, David E; Kim, Chul-Hyun; Kao, C Cheng

    2018-01-09

    In the brome mosaic virus (BMV) virion, the coat protein (CP) selectively contacts the RNA motifs that regulate translation and RNA replication (Hoover et al., 2016. J. Virol. 90, 7748). We hypothesize that the unstructured N-terminal arm (NTA) of the BMV CP can specifically recognize RNA motifs. Using ion mobility spectrometry-mass spectrometry, we demonstrate that peptides containing the NTA of the CP were found to preferentially bind to an RNA hairpin motif that directs the initiation of BMV RNA synthesis. RNA binding causes the peptide to change from heterogeneous structures to a single family of structures. Fluorescence anisotropy, fluorescence quenching and size exclusion chromatography experiments all confirm that the NTA can specific recognize the RNA motif. The peptide introduced into plants along with BMV virion increased accumulation of the BMV CP and accelerated the rate of minus-strand RNA synthesis. The intrinsically disordered BMV NTA could thus specifically recognize BMV RNAs to affect viral infection. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  8. GAPDH--a recruits a plant virus movement protein to cortical virus replication complexes to facilitate viral cell-to-cell movement.

    Directory of Open Access Journals (Sweden)

    Masanori Kaido

    2014-11-01

    Full Text Available The formation of virus movement protein (MP-containing punctate structures on the cortical endoplasmic reticulum is required for efficient intercellular movement of Red clover necrotic mosaic virus (RCNMV, a bipartite positive-strand RNA plant virus. We found that these cortical punctate structures constitute a viral replication complex (VRC in addition to the previously reported aggregate structures that formed adjacent to the nucleus. We identified host proteins that interacted with RCNMV MP in virus-infected Nicotiana benthamiana leaves using a tandem affinity purification method followed by mass spectrometry. One of these host proteins was glyceraldehyde 3-phosphate dehydrogenase-A (NbGAPDH-A, which is a component of the Calvin-Benson cycle in chloroplasts. Virus-induced gene silencing of NbGAPDH-A reduced RCNMV multiplication in the inoculated leaves, but not in the single cells, thereby suggesting that GAPDH-A plays a positive role in cell-to-cell movement of RCNMV. The fusion protein of NbGAPDH-A and green fluorescent protein localized exclusively to the chloroplasts. In the presence of RCNMV RNA1, however, the protein localized to the cortical VRC as well as the chloroplasts. Bimolecular fluorescence complementation assay and GST pulldown assay confirmed in vivo and in vitro interactions, respectively, between the MP and NbGAPDH-A. Furthermore, gene silencing of NbGAPDH-A inhibited MP localization to the cortical VRC. We discuss the possible roles of NbGAPDH-A in the RCNMV movement process.

  9. Inhibition of BmNPV replication in silkworm cells using inducible and regulated artificial microRNA precursors targeting the essential viral gene lef-11.

    Science.gov (United States)

    Zhang, Jun; He, Qian; Zhang, Chun-Dong; Chen, Xiang-Yun; Chen, Xue-Mei; Dong, Zhan-Qi; Li, Na; Kuang, Xiu-Xiu; Cao, Ming-Ya; Lu, Cheng; Pan, Min-Hui

    2014-04-01

    Bombyx mori nucleopolyhedrovirus (BmNPV) is a major silkworm pathogen, causing substantial economic losses to the sericulture industry annually. We demonstrate a novel anti-BmNPV system expressing mature artificial microRNAs (amiRNAs) targeting the viral lef-11 gene. The mature amiRNAs inhibited the lef-11 gene in silkworm BmN-SWU1 cells. Antiviral assays demonstrated that mature amiRNAs silenced the gene and inhibited BmNPV proliferation efficiently. As constitutive overexpression of mature amiRNAs may induce acute cellular toxicity, we further developed a novel virus-induced amiRNA expression system. The amiRNA cassette is regulated by a baculovirus-induced fusion promoter. This baculovirus-induced RNA interference system is strictly regulated by virus infection, which functions in a negative feedback loop to activate the expression of mature amiRNAs against lef-11 and subsequently control inhibition of BmNPV replication. Our study advances the use of a regulatable amiRNA cassette as a safe and effective tool for research of basic insect biology and antiviral application. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Herpes simplex virus type 1-induced FasL expression in human monocytic cells and its implications for cell death, viral replication, and immune evasion.

    Science.gov (United States)

    Iannello, Alexandre; Debbeche, Olfa; El Arabi, Raoudha; Samarani, Suzanne; Hamel, David; Rozenberg, Flore; Heveker, Nikolaus; Ahmad, Ali

    2011-02-01

    Herpes simplex virus type 1 (HSV-1) is a ubiquitously occurring pathogen that infects humans early in childhood. The virus persists as a latent infection in dorsal root ganglia, especially of the trigeminal nerve, and frequently becomes reactivated in humans under conditions of stress. Monocytic cells constitute an important component of the innate and adaptive immune responses. We show here for the first time that HSV-1 stimulates human FasL promoter and induces de novo expression of FasL on the surface of human monocytic cells, including monocytes and macrophages. This virus-induced FasL expression causes death of monocytic cells growing in suspension, but not in monolayers (e.g., macrophages). The addition of a broad-spectrum caspase inhibitor, as well as anti-FasL antibodies, reduced cell death but increased viral replication in the virus-infected cell cultures. We also show here for the first time that the virus-induced de novo expression of FasL on the cell surface acts as an immune evasion mechanism by causing the death of interacting human CD4+ T cells, CD8+ T cells, and natural killer (NK) cells. Our study provides novel insights on FasL expression and cell death in HSV-infected human monocytic cells and their impact on interacting immune cells.

  11. Experimental infection with the Paderborn isolate of classical swine fever virus in 10-week-old pigs: determination of viral replication kinetics by quantitative RT-PCR, virus isolation and antigen ELISA

    DEFF Research Database (Denmark)

    Uttenthal, Åse; Storgaard, Torben; Oleksiewicz, M.B.

    2003-01-01

    We performed experimental infection in 10-week-old pigs with the Paderborn isolate of classical swine fever virus (CSFV). Despite being epidemiologically linked to the major CSFV outbreak in The Netherlands in 1997, the in vivo replication kinetics of this isolate have to our knowledge not been...... described in detail previously. We found that oronasal infection with 10(4.7) TCID50 produced mortality in three out of five pigs after 29-31 days, and severe clinical symptoms in one out of five pigs, while one out of five pigs exhibited no clinical symptoms. At this infection dose, pigs had viral RNA...... viral RNA in serum for more than 30 days, and exhibited only mild clinical symptoms. We observed an excellent correlation between clinical symptoms and viral RNA loads in serum, while serum antibody levels were low. Clinically affected pigs had up to 1000-fold higher serum viral RNA loads than did pigs...

  12. Suppressing active replication of a live attenuated simian immunodeficiency virus vaccine does not abrogate protection from challenge

    International Nuclear Information System (INIS)

    Gabriel, Benjamin; Fiebig, Uwe; Hohn, Oliver; Plesker, Roland; Coulibaly, Cheick; Cichutek, Klaus; Mühlebach, Michael D.; Bannert, Norbert; Kurth, Reinhard; Norley, Stephen

    2016-01-01

    Although safety concerns preclude the use of live attenuated HIV vaccines in humans, they provide a useful system for identifying the elusive correlates of protective immunity in the SIV/macaque animal model. However, a number of pieces of evidence suggest that protection may result from prior occupancy of susceptible target cells by the vaccine virus rather than the immune response. To address this, we developed a Nef-deletion variant of an RT-SHIV whose active replication could be shut off by treatment with RT-inhibitors. Groups of macaques were inoculated with the ∆Nef-RT-SHIV and immune responses allowed to develop before antiretroviral treatment and subsequent challenge with wild-type SIVmac239. Vaccinated animals either resisted infection fully or significantly controlled the subsequent viremia. However, there was no difference between animals undergoing replication of the vaccine virus and those without. This strongly suggests that competition for available target cells does not play a role in protection. - Highlights: • A Nef-deleted RT-SHIV was used as a live attenuated vaccine in macaques. • Vaccine virus replication was shut down to investigate its role in protection. • Ongoing vaccine virus replication did not appear to be necessary for protection. • An analysis of T- and B-cell responses failed to identify a correlate of protection.

  13. Inhibition of cyclophilin A suppresses H2O2-enhanced replication of HCMV through the p38 MAPK signaling pathway.

    Science.gov (United States)

    Xiao, Jun; Song, Xin; Deng, Jiang; Lv, Liping; Ma, Ping; Gao, Bo; Zhou, Xipeng; Zhang, Yanyu; Xu, Jinbo

    2016-09-01

    Human cytomegalovirus (HCMV) infection can be accelerated by intracellular and extracellular hydrogen peroxide (H2O2) stimulation, mediated by the activation of the p38 mitogen-activated protein kinase (MAPK) pathway. However, it remains unknown whether host gene expression is involved in H2O2-upregulated HCMV replication. Here, we show that the expression of the host gene, cyclophilin A (CyPA), could be facilitated by treatment with H2O2 in a dose-dependent manner. Experiments with CyPA-specific siRNA, or with cyclosporine A, an inhibitor of CyPA, confirmed that H2O2-mediated upregulation of HCMV replication is specifically mediated by upregulation of CyPA expression. Furthermore, depletion or inhibition of CyPA reduced H2O2-induced p38 activation, consistent with that of H2O2-upregulated HCMV lytic replication. These results show that H2O2 is capable of activating ROS-CyPA-p38 MAPK interactions to enhance HCMV replication.

  14. Suppressing active replication of a live attenuated simian immunodeficiency virus vaccine does not abrogate protection from challenge

    Energy Technology Data Exchange (ETDEWEB)

    Gabriel, Benjamin; Fiebig, Uwe; Hohn, Oliver [Robert Koch-Institut, Berlin (Germany); Plesker, Roland; Coulibaly, Cheick; Cichutek, Klaus; Mühlebach, Michael D. [Paul-Ehrlich-Institut, Langen (Germany); Bannert, Norbert; Kurth, Reinhard [Robert Koch-Institut, Berlin (Germany); Norley, Stephen, E-mail: NorleyS@rki.de [Robert Koch-Institut, Berlin (Germany)

    2016-02-15

    Although safety concerns preclude the use of live attenuated HIV vaccines in humans, they provide a useful system for identifying the elusive correlates of protective immunity in the SIV/macaque animal model. However, a number of pieces of evidence suggest that protection may result from prior occupancy of susceptible target cells by the vaccine virus rather than the immune response. To address this, we developed a Nef-deletion variant of an RT-SHIV whose active replication could be shut off by treatment with RT-inhibitors. Groups of macaques were inoculated with the ∆Nef-RT-SHIV and immune responses allowed to develop before antiretroviral treatment and subsequent challenge with wild-type SIVmac239. Vaccinated animals either resisted infection fully or significantly controlled the subsequent viremia. However, there was no difference between animals undergoing replication of the vaccine virus and those without. This strongly suggests that competition for available target cells does not play a role in protection. - Highlights: • A Nef-deleted RT-SHIV was used as a live attenuated vaccine in macaques. • Vaccine virus replication was shut down to investigate its role in protection. • Ongoing vaccine virus replication did not appear to be necessary for protection. • An analysis of T- and B-cell responses failed to identify a correlate of protection.

  15. miR-200c targets nuclear factor IA to suppress HBV replication and gene expression via repressing HBV Enhancer I activity.

    Science.gov (United States)

    Tian, Hui; He, Zhenkun

    2018-03-01

    Hepatitis B virus (HBV) chronic infection is a health problem in the worldwide, with a underlying higher risk of liver cirrhosis and hepaticocellular carcinoma. A number of studies indicate that microRNAs (miRNAs) play vital roles in HBV replication. This study was designed to explore the potential molecular mechanism of miR-200c in HBV replication. The expression of miR-200c, nuclear factor IA (NFIA) mRNA, HBV DNA, and HBV RNA (pregenomic RNA (pgRNA), and total RNA) were measured by qRCR. The levels of HBsAg and HBeAg were detected by ELISA. NFIA expression at protein level was measured by western blot. The direct interaction between miR-200c and NFIA were identified by Targetscan software and Dual-Luciferase reporter analysis. Enhance I activity were detected by Dual-Luciferase reporter assay. miR-200c expression was prominently reduced in pHBV1.3-tranfected Huh7 and in stable HBV-producing cell line (HepG2.2.15). The enforced expression of miR-200c significantly suppressed HBV replication, as demonstrated by the reduced levels of HBV protein (HBsAg and HBeAg) and, DNA and RNA (pgRNA and total RNA) levels. NFIA was proved to be a target of miR-200c and NFIA overexpression notably stimulated HBV replication. In addition, the inhibitory effect of miR-200c on HBV Enhance I activity was abolished following restoration of NFIA. miR-200c repressed HBV replication by directly targeting NFIA, which might provide a novel therapeutic target for HBV infection. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  16. Direct infection of dendritic cells during chronic viral infection suppresses antiviral T cell proliferation and induces IL-10 expression in CD4 T cells.

    Directory of Open Access Journals (Sweden)

    Carmen Baca Jones

    Full Text Available Elevated levels of systemic IL-10 have been associated with several chronic viral infections, including HCV, EBV, HCMV and LCMV. In the chronic LCMV infection model, both elevated IL-10 and enhanced infection of dendritic cells (DCs are important for viral persistence. This report highlights the relationship between enhanced viral tropism for DCs and the induction of IL-10 in CD4 T cells, which we identify as the most frequent IL-10-expressing cell type in chronic LCMV infection. Here we report that infected CD8αneg DCs express elevated IL-10, induce IL-10 expression in LCMV specific CD4 T cells, and suppress LCMV-specific T cell proliferation. DCs exposed in vivo to persistent LCMV retain the capacity to stimulate CD4 T cell proliferation but induce IL-10 production by both polyclonal and LCMV-specific CD4 T cells. Our study delineates the unique effects of direct infection versus viral exposure on DCs. Collectively these data point to enhanced infection of DCs as a key trigger of the IL-10 induction cascade resulting in maintenance of elevated IL-10 expression in CD4 T cells and inhibition of LCMV-specific CD4 and CD8 T cell proliferation.

  17. Influence of Jail Incarceration and Homelessness Patterns on Engagement in HIV Care and HIV Viral Suppression among New York City Adults Living with HIV/AIDS.

    Directory of Open Access Journals (Sweden)

    Sungwoo Lim

    Full Text Available Both homelessness and incarceration are associated with housing instability, which in turn can disrupt continuity of HIV medical care. Yet, their impacts have not been systematically assessed among people living with HIV/AIDS (PLWHA.We studied a retrospective cohort of 1,698 New York City PLWHA with both jail incarceration and homelessness during 2001-05 to evaluate whether frequent transitions between jail incarceration and homelessness were associated with a lower likelihood of continuity of HIV care during a subsequent one-year follow-up period. Using matched jail, single-adult homeless shelter, and HIV registry data, we performed sequence analysis to identify trajectories of these events and assessed their influence on engagement in HIV care and HIV viral suppression via marginal structural modeling.Sequence analysis identified four trajectories; 72% of the cohort had sporadic experiences of both brief incarceration and homelessness, whereas others experienced more consistent incarceration or homelessness during early or late months. Trajectories were not associated with differential engagement in HIV care during follow-up. However, compared with PLWHA experiencing early bouts of homelessness and later minimal incarceration/homelessness events, we observed a lower prevalence of viral suppression among PLWHA with two other trajectories: those with sporadic, brief occurrences of incarceration/homelessness (0.67, 95% CI = 0.50,0.90 and those with extensive incarceration experiences (0.62, 95% CI = 0.43,0.88.Housing instability due to frequent jail incarceration and homelessness or extensive incarceration may exert negative influences on viral suppression. Policies and services that support housing stability should be strengthened among incarcerated and sheltered PLWHA to reduce risk of adverse health conditions.

  18. Long-term Mortality in HIV-Positive Individuals Virally Suppressed for >3 Years With Incomplete CD4 Recovery

    DEFF Research Database (Denmark)

    Engsig, Frederik N; Zangerle, Robert; Katsarou, Olga

    2014-01-01

    of the suppressed period. Logistic regression was used to identify risk factors for incomplete CD4 recovery (≤200 cells/µL) and Cox regression to identify associations with mortality. RESULTS: Of 5550 eligible individuals, 835 (15%) did not reach a CD4 count >200 cells/µL after 3 years of suppression. Increasing...

  19. Suppression of leaky expression of adenovirus genes by insertion of microRNA-targeted sequences in the replication-incompetent adenovirus vector genome

    Directory of Open Access Journals (Sweden)

    Kahori Shimizu

    2014-01-01

    Full Text Available Leaky expression of adenovirus (Ad genes occurs following transduction with a conventional replication-incompetent Ad vector, leading to an induction of cellular immunity against Ad proteins and Ad protein-induced toxicity, especially in the late phase following administration. To suppress the leaky expression of Ad genes, we developed novel Ad vectors by incorporating four tandem copies of sequences with perfect complementarity to miR-122a or miR-142-3p into the 3′-untranslated region (UTR of the E2A, E4, or pIX gene, which were mainly expressed from the Ad vector genome after transduction. These Ad vectors easily grew to high titers comparable to those of a conventional Ad vector in conventional 293 cells. The leaky expression of these Ad genes in mouse organs was significantly suppressed by 2- to 100-fold, compared with a conventional Ad vector, by insertion of the miRNA-targeted sequences. Notably, the Ad vector carrying the miR-122a–targeted sequences into the 3′-UTR of the E4 gene expressed higher and longer-term transgene expression and more than 20-fold lower levels of all the Ad early and late genes examined in the liver than a conventional Ad vector. miR-122a–mediated suppression of the E4 gene expression in the liver significantly reduced the hepatotoxicity which an Ad vector causes via both adaptive and non-adaptive immune responses.

  20. A comparison of self-report and antiretroviral detection to inform estimates of antiretroviral therapy coverage, viral load suppression and HIV incidence in Kwazulu-Natal, South Africa.

    Science.gov (United States)

    Huerga, Helena; Shiferie, Fisseha; Grebe, Eduard; Giuliani, Ruggero; Farhat, Jihane Ben; Van-Cutsem, Gilles; Cohen, Karen

    2017-09-29

    Accurately identifying individuals who are on antiretroviral therapy (ART) is important to determine ART coverage and proportion on ART who are virally suppressed. ART is also included in recent infection testing algorithms used to estimate incidence. We compared estimates of ART coverage, viral load suppression rates and HIV incidence using ART self-report and detection of antiretroviral (ARV) drugs and we identified factors associated with discordance between the methods. Cross-sectional population-based survey in KwaZulu-Natal, South Africa. Individuals 15-59 years were eligible. Interviews included questions about ARV use. Rapid HIV testing was performed at the participants' home. Blood specimens were collected for ARV detection, LAg-Avidity HIV incidence testing and viral load quantification in HIV-positive individuals. Multivariate logistic regression models were used to identify socio-demographic covariates associated with discordance between self-reported ART and ARV detection. Of the 5649 individuals surveyed, 1423 were HIV-positive. Median age was 34 years and 76.3% were women. ART coverage was estimated at 51.4% (95%CI:48.5-54.3), 53.1% (95%CI:50.2-55.9) and 56.1% (95%CI:53.5-58.8) using self-reported ART, ARV detection and both methods combined (classified as ART exposed if ARV detected and/or ART reported) respectively. ART coverage estimates using the 3 methods were fairly similar within sex and age categories except in individuals aged 15-19 years: 33.3% (95%CI:23.3-45.2), 33.8% (95%CI:23.9-45.4%) and 44.3% (95%CI:39.3-46.7) using self-reported ART, ARV detection and both methods combined. Viral suppression below 1000cp/mL in individuals on ART was estimated at 89.8% (95%CI:87.3-91.9), 93.1% (95%CI:91.0-94.8) and 88.7% (95%CI:86.2-90.7) using self-reported ART, ARV detection and both methods combined respectively. HIV incidence was estimated at 1.4 (95%CI:0.8-2.0) new cases/100 person-years when employing no measure of ARV use, 1.1/100PY (95%CI:0

  1. Serine 192 in the tiny RS repeat of the adenoviral L4-33K splicing enhancer protein is essential for function and reorganization of the protein to the periphery of viral replication centers

    Energy Technology Data Exchange (ETDEWEB)

    Oestberg, Sara, E-mail: sara.ostberg@imbim.uu.se [Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 75123 Uppsala (Sweden); Toermaenen Persson, Heidi, E-mail: heidi.tormanen.persson@imbim.uu.se [Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 75123 Uppsala (Sweden); Akusjaervi, Goeran, E-mail: goran.akusjarvi@imbim.uu.se [Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, 75123 Uppsala (Sweden)

    2012-11-25

    The adenovirus L4-33K protein is a key regulator involved in the temporal shift from early to late pattern of mRNA expression from the adenovirus major late transcription unit. L4-33K is a virus-encoded alternative splicing factor, which enhances processing of 3 Prime splice sites with a weak sequence context. Here we show that L4-33K expressed from a plasmid is localized at the nuclear margin of uninfected cells. During an infection L4-33K is relocalized to the periphery of E2A-72K containing viral replication centers. We also show that serine 192 in the tiny RS repeat of the conserved carboxy-terminus of L4-33K, which is critical for the splicing enhancer function of L4-33K, is necessary for the nuclear localization and redistribution of the protein to viral replication sites. Collectively, our results show a good correlation between the activity of L4-33K as a splicing enhancer protein and its localization to the periphery of viral replication centers.

  2. Suppression of cytochrome P450 reductase (POR) expression in hepatoma cells replicates the hepatic lipidosis observed in hepatic POR-null mice.

    Science.gov (United States)

    Porter, Todd D; Banerjee, Subhashis; Stolarczyk, Elzbieta I; Zou, Ling

    2011-06-01

    Cytochrome P450 reductase (POR) is a microsomal electron transport protein essential to cytochrome P450-mediated drug metabolism and sterol and bile acid synthesis. The conditional deletion of hepatic POR gene expression in mice results in a marked decrease in plasma cholesterol levels counterbalanced by the accumulation of triglycerides in lipid droplets in hepatocytes. To evaluate the role of cholesterol and bile acid synthesis in this hepatic lipidosis, as well as the possible role of lipid transport from peripheral tissues, we developed a stable, small interfering RNA (siRNA)-mediated cell culture model for the suppression of POR. POR mRNA and protein expression were decreased by greater than 50% in McArdle-RH7777 rat hepatoma cells 10 days after transfection with a POR-siRNA expression plasmid, and POR expression was nearly completely extinguished by day 20. Immunofluorescent analysis revealed a marked accumulation of lipid droplets in cells by day 15, accompanied by a nearly 2-fold increase in cellular triglyceride content, replicating the lipidosis seen in hepatic POR-null mouse liver. In contrast, suppression of CYP51A1 (lanosterol demethylase) did not result in lipid accumulation, indicating that loss of cholesterol synthesis is not the basis for this lipidosis. Indeed, addition of cholesterol to the medium appeared to augment the lipidosis in POR-suppressed cells, whereas removal of lipids from the medium reversed the lipidosis. Oxysterols did not accumulate in POR-suppressed cells, discounting a role for liver X receptor in stimulating triglyceride synthesis, but addition of chenodeoxycholate significantly repressed lipid accumulation, suggesting that the absence of bile acids and loss of farnesoid X receptor stimulation lead to excessive triglyceride synthesis.

  3. Higher risk sexual behaviour is associated with unawareness of HIV-positivity and lack of viral suppression - implications for Treatment as Prevention.

    Science.gov (United States)

    Huerga, Helena; Venables, Emilie; Ben-Farhat, Jihane; van Cutsem, Gilles; Ellman, Tom; Kenyon, Chris

    2017-11-23

    Efficacy of Treatment as Prevention Strategy depends on a variety of factors including individuals' likelihood to test and initiate treatment, viral load and sexual behaviour. We tested the hypothesis that people with higher risk sexual behaviour are less likely to know their HIV-positive status and be virologically suppressed. A cross-sectional population-based survey of individuals aged 15-59 years old was conducted in 2013 in KwaZulu-Natal, South Africa. A two-stage cluster probability sampling was used. After adjustment for age and sex, lack of awareness of HIV-positivity was strongly associated with having more than one sexual partner in the preceding year (aOR: 2.1, 95%CI: 1.5-3.1). Inconsistent condom use was more common in individuals with more than one sexual partner (aOR: 16.6, 95%CI: 7.6-36.7) and those unaware (aOR: 3.7, 95%CI: 2.6-5.4). Among people aware of their HIV-positivity, higher risk sexual behaviour was associated with lack of viral suppression (aOR: 2.2, 95%CI: 1.1-4.5). Risky sexual behaviour seems associated with factors linked to poor health-seeking behaviour which may have negative implications for HIV testing and Treatment as Prevention. Innovative strategies, driven by improved epidemiological and anthropological understanding, are needed to enable comprehensive approaches to HIV prevention.

  4. The expanding functions of cellular helicases: the tombusvirus RNA replication enhancer co-opts the plant eIF4AIII-like AtRH2 and the DDX5-like AtRH5 DEAD-box RNA helicases to promote viral asymmetric RNA replication.

    Directory of Open Access Journals (Sweden)

    Nikolay Kovalev

    2014-04-01

    Full Text Available Replication of plus-strand RNA viruses depends on recruited host factors that aid several critical steps during replication. Several of the co-opted host factors bind to the viral RNA, which plays multiple roles, including mRNA function, as an assembly platform for the viral replicase (VRC, template for RNA synthesis, and encapsidation during infection. It is likely that remodeling of the viral RNAs and RNA-protein complexes during the switch from one step to another requires RNA helicases. In this paper, we have discovered a second group of cellular RNA helicases, including the eIF4AIII-like yeast Fal1p and the DDX5-like Dbp3p and the orthologous plant AtRH2 and AtRH5 DEAD box helicases, which are co-opted by tombusviruses. Unlike the previously characterized DDX3-like AtRH20/Ded1p helicases that bind to the 3' terminal promoter region in the viral minus-strand (-RNA, the other class of eIF4AIII-like RNA helicases bind to a different cis-acting element, namely the 5' proximal RIII(- replication enhancer (REN element in the TBSV (-RNA. We show that the binding of AtRH2 and AtRH5 helicases to the TBSV (-RNA could unwind the dsRNA structure within the RIII(- REN. This unique characteristic allows the eIF4AIII-like helicases to perform novel pro-viral functions involving the RIII(- REN in stimulation of plus-strand (+RNA synthesis. We also show that AtRH2 and AtRH5 helicases are components of the tombusvirus VRCs based on co-purification experiments. We propose that eIF4AIII-like helicases destabilize dsRNA replication intermediate within the RIII(- REN that promotes bringing the 5' and 3' terminal (-RNA sequences in close vicinity via long-range RNA-RNA base pairing. This newly formed RNA structure promoted by eIF4AIII helicase together with AtRH20 helicase might facilitate the recycling of the viral replicases for multiple rounds of (+-strand synthesis, thus resulting in asymmetrical viral replication.

  5. The expanding functions of cellular helicases: the tombusvirus RNA replication enhancer co-opts the plant eIF4AIII-like AtRH2 and the DDX5-like AtRH5 DEAD-box RNA helicases to promote viral asymmetric RNA replication.

    Science.gov (United States)

    Kovalev, Nikolay; Nagy, Peter D

    2014-04-01

    Replication of plus-strand RNA viruses depends on recruited host factors that aid several critical steps during replication. Several of the co-opted host factors bind to the viral RNA, which plays multiple roles, including mRNA function, as an assembly platform for the viral replicase (VRC), template for RNA synthesis, and encapsidation during infection. It is likely that remodeling of the viral RNAs and RNA-protein complexes during the switch from one step to another requires RNA helicases. In this paper, we have discovered a second group of cellular RNA helicases, including the eIF4AIII-like yeast Fal1p and the DDX5-like Dbp3p and the orthologous plant AtRH2 and AtRH5 DEAD box helicases, which are co-opted by tombusviruses. Unlike the previously characterized DDX3-like AtRH20/Ded1p helicases that bind to the 3' terminal promoter region in the viral minus-strand (-)RNA, the other class of eIF4AIII-like RNA helicases bind to a different cis-acting element, namely the 5' proximal RIII(-) replication enhancer (REN) element in the TBSV (-)RNA. We show that the binding of AtRH2 and AtRH5 helicases to the TBSV (-)RNA could unwind the dsRNA structure within the RIII(-) REN. This unique characteristic allows the eIF4AIII-like helicases to perform novel pro-viral functions involving the RIII(-) REN in stimulation of plus-strand (+)RNA synthesis. We also show that AtRH2 and AtRH5 helicases are components of the tombusvirus VRCs based on co-purification experiments. We propose that eIF4AIII-like helicases destabilize dsRNA replication intermediate within the RIII(-) REN that promotes bringing the 5' and 3' terminal (-)RNA sequences in close vicinity via long-range RNA-RNA base pairing. This newly formed RNA structure promoted by eIF4AIII helicase together with AtRH20 helicase might facilitate the recycling of the viral replicases for multiple rounds of (+)-strand synthesis, thus resulting in asymmetrical viral replication.

  6. Structure-function relationship of viral cis-acting RNA elements : the role of the OriI and OriR in enterovirus replication

    NARCIS (Netherlands)

    Ooij, Martinus Johannes Maria van

    2007-01-01

    The genus Enterovirus belongs to Picornaviridae, a family of small, non-enveloped, lytic RNA viruses. They contain a single-stranded RNA genome of positive polarity of approximately 7,500 nucleotides. A viral protein VPg is specifically linked to the 5'terminus of the viral RNA. IRES-mediated

  7. Enhanced suppression of adenovirus replication by triple combination of anti-adenoviral siRNAs, soluble adenovirus receptor trap sCAR-Fc and cidofovir.

    Science.gov (United States)

    Pozzuto, Tanja; Röger, Carsten; Kurreck, Jens; Fechner, Henry

    2015-08-01

    Adenoviruses (Ad) generally induce mild self-limiting respiratory or intestinal infections but can also cause serious disease with fatal outcomes in immunosuppressed patients. Antiviral drug therapy is an important treatment for adenoviral infections but its efficiency is limited. Recently, we have shown that gene silencing by RNA interference (RNAi) is a promising new approach to inhibit adenoviral infection. In the present in vitro study, we examined whether the efficiency of an RNAi-based anti-adenoviral therapy can be further increased by combination with a virus receptor trap sCAR-Fc and with the antiviral drug cidofovir. Initially, three siRNAs, siE1A_4, siIVa2_2 and Pol-si2, targeting the adenoviral E1A, IVa2 and DNA polymerase mRNAs, respectively, were used for gene silencing. Replication of the Ad was inhibited in a dose dependent manner by each siRNA, but the efficiency of inhibition differed (Pol-si2>siIVa2_2>siE1A_4). Double or triple combinations of the siRNAs compared with single siRNAs did not result in a measurably higher suppression of Ad replication. Combination of the siRNAs (alone or mixes of two or three siRNAs) with sCAR-Fc markedly increased the suppression of adenoviral replication compared to the same siRNA treatment without sCAR-Fc. Moreover, the triple combination of a mix of all three siRNAs, sCAR-Fc and cidofovir was about 23-fold more efficient than the combination of siRNAs mix/sCAR-Fc and about 95-fold more efficient than the siRNA mix alone. These data demonstrate that co-treatment of cells with sCAR-Fc and cidofovir is suitable to increase the efficiency of anti-adenoviral siRNAs. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Brief Report: Prolonged Viral Suppression Over a 12-Year Follow-up of HIV-Infected Patients: The Persistent Impact of Adherence at 4 Months After Initiation of Combined Antiretroviral Therapy in the ANRS CO8 APROCO-COPILOTE Cohort.

    Science.gov (United States)

    Protopopescu, Camelia; Carrieri, Maria P; Raffi, François; Picard, Odile; Hardel, Lucile; Piroth, Lionel; Jadand, Corinne; Pierret, Janine; Spire, Bruno; Leport, Catherine

    2017-03-01

    The effect of early adherence on long-term viral suppression was assessed among 1281 patients with HIV starting a protease inhibitor-containing regimen in 1997-1999, followed up to 12 years. Association between 4-month adherence (3-level score) and prolonged viral suppression was evaluated using a multivariate mixed logistic model in 891 eligible patients. High 4-months adherence [odds ratio (95% confidence interval): 3.72 (1.98 to 6.98)] was associated with long-term prolonged viral suppression, irrespective of maintenance adherence. This unexpected long-term virological impact of early adherence reinforces the message that, when starting antiretrovirals, all means should be mobilized to ensure optimum early adherence to achieve prolonged antiretroviral success.

  9. Replication-uncoupled histone deposition during adenovirus DNA replication.

    Science.gov (United States)

    Komatsu, Tetsuro; Nagata, Kyosuke

    2012-06-01

    In infected cells, the chromatin structure of the adenovirus genome DNA plays critical roles in its genome functions. Previously, we reported that in early phases of infection, incoming viral DNA is associated with both viral core protein VII and cellular histones. Here we show that in late phases of infection, newly synthesized viral DNA is also associated with histones. We also found that the knockdown of CAF-1, a histone chaperone that functions in the replication-coupled deposition of histones, does not affect the level of histone H3 bound on viral chromatin, although CAF-1 is accumulated at viral DNA replication foci together with PCNA. Chromatin immunoprecipitation assays using epitope-tagged histone H3 demonstrated that histone variant H3.3, which is deposited onto the cellular genome in a replication-independent manner, is selectively associated with both incoming and newly synthesized viral DNAs. Microscopic analyses indicated that histones but not USF1, a transcription factor that regulates viral late gene expression, are excluded from viral DNA replication foci and that this is achieved by the oligomerization of the DNA binding protein (DBP). Taken together, these results suggest that histone deposition onto newly synthesized viral DNA is most likely uncoupled with viral DNA replication, and a possible role of DBP oligomerization in this replication-uncoupled histone deposition is discussed.

  10. Human immunodeficiency virus integrase inhibitors efficiently suppress feline immunodeficiency virus replication in vitro and provide a rationale to redesign antiretroviral treatment for feline AIDS

    Science.gov (United States)

    Savarino, Andrea; Pistello, Mauro; D'Ostilio, Daniela; Zabogli, Elisa; Taglia, Fabiana; Mancini, Fabiola; Ferro, Stefania; Matteucci, Donatella; De Luca, Laura; Barreca, Maria Letizia; Ciervo, Alessandra; Chimirri, Alba; Ciccozzi, Massimo; Bendinelli, Mauro

    2007-01-01

    Background Treatment of feline immunodeficiency virus (FIV) infection has been hampered by the absence of a specific combination antiretroviral treatment (ART). Integrase strand transfer inhibitors (INSTIs) are emerging as a promising new drug class for HIV-1 treatment, and we evaluated the possibility of inhibiting FIV replication using INSTIs. Methods Phylogenetic analysis of lentiviral integrase (IN) sequences was carried out using the PAUP* software. A theoretical three-dimensional structure of the FIV IN catalytic core domain (CCD) was obtained by homology modeling based on a crystal structure of HIV-1 IN CCD. The interaction of the transferred strand of viral DNA with the catalytic cavity of FIV IN was deduced from a crystal structure of a structurally similar transposase complexed with transposable DNA. Molecular docking simulations were conducted using a genetic algorithm (GOLD). Antiviral activity was tested in feline lymphoblastoid MBM cells acutely infected with the FIV Petaluma strain. Circular and total proviral DNA was quantified by real-time PCR. Results The calculated INSTI-binding sites were found to be nearly identical in FIV and HIV-1 IN CCDs. The close similarity of primate and feline lentivirus IN CCDs was also supported by phylogenetic analysis. In line with these bioinformatic analyses, FIV replication was efficiently inhibited in acutely infected cell cultures by three investigational INSTIs, designed for HIV-1 and belonging to different classes. Of note, the naphthyridine carboxamide INSTI, L-870,810 displayed an EC50 in the low nanomolar range. Inhibition of FIV integration in situ was shown by real-time PCR experiments that revealed accumulation of circular forms of FIV DNA within cells treated with L-870,810. Conclusion We report a drug class (other than nucleosidic reverse transcriptase inhibitors) that is capable of inhibiting FIV replication in vitro. The present study helped establish L-870,810, a compound successfully tested in

  11. Human immunodeficiency virus integrase inhibitors efficiently suppress feline immunodeficiency virus replication in vitro and provide a rationale to redesign antiretroviral treatment for feline AIDS

    Directory of Open Access Journals (Sweden)

    Ciervo Alessandra

    2007-10-01

    Full Text Available Abstract Background Treatment of feline immunodeficiency virus (FIV infection has been hampered by the absence of a specific combination antiretroviral treatment (ART. Integrase strand transfer inhibitors (INSTIs are emerging as a promising new drug class for HIV-1 treatment, and we evaluated the possibility of inhibiting FIV replication using INSTIs. Methods Phylogenetic analysis of lentiviral integrase (IN sequences was carried out using the PAUP* software. A theoretical three-dimensional structure of the FIV IN catalytic core domain (CCD was obtained by homology modeling based on a crystal structure of HIV-1 IN CCD. The interaction of the transferred strand of viral DNA with the catalytic cavity of FIV IN was deduced from a crystal structure of a structurally similar transposase complexed with transposable DNA. Molecular docking simulations were conducted using a genetic algorithm (GOLD. Antiviral activity was tested in feline lymphoblastoid MBM cells acutely infected with the FIV Petaluma strain. Circular and total proviral DNA was quantified by real-time PCR. Results The calculated INSTI-binding sites were found to be nearly identical in FIV and HIV-1 IN CCDs. The close similarity of primate and feline lentivirus IN CCDs was also supported by phylogenetic analysis. In line with these bioinformatic analyses, FIV replication was efficiently inhibited in acutely infected cell cultures by three investigational INSTIs, designed for HIV-1 and belonging to different classes. Of note, the naphthyridine carboxamide INSTI, L-870,810 displayed an EC50 in the low nanomolar range. Inhibition of FIV integration in situ was shown by real-time PCR experiments that revealed accumulation of circular forms of FIV DNA within cells treated with L-870,810. Conclusion We report a drug class (other than nucleosidic reverse transcriptase inhibitors that is capable of inhibiting FIV replication in vitro. The present study helped establish L-870,810, a compound

  12. Different effect of proteasome inhibition on vesicular stomatitis virus and poliovirus replication.

    Directory of Open Access Journals (Sweden)

    Nickolay Neznanov

    2008-04-01

    Full Text Available Proteasome activity is an important part of viral replication. In this study, we examined the effect of proteasome inhibitors on the replication of vesicular stomatitis virus (VSV and poliovirus. We found that the proteasome inhibitors significantly suppressed VSV protein synthesis, virus accumulation, and protected infected cells from toxic effect of VSV replication. In contrast, poliovirus replication was delayed, but not diminished in the presence of the proteasome inhibitors MG132 and Bortezomib. We also found that inhibition of proteasomes stimulated stress-related processes, such as accumulation of chaperone hsp70, phosphorylation of eIF2alpha, and overall inhibition of translation. VSV replication was sensitive to this stress with significant decline in replication process. Poliovirus growth was less sensitive with only delay in replication. Inhibition of proteasome activity suppressed cellular and VSV protein synthesis, but did not reduce poliovirus protein synthesis. Protein kinase GCN2 supported the ability of proteasome inhibitors to attenuate general translation and to suppress VSV replication. We propose that different mechanisms of translational initiation by VSV and poliovirus determine their sensitivity to stress induced by the inhibition of proteasomes. To our knowledge, this is the first study that connects the effect of stress induced by proteasome inhibition with the efficiency of viral infection.

  13. Cellular microRNA miR-26a suppresses replication of porcine reproductive and respiratory syndrome virus by activating innate antiviral immunity.

    Science.gov (United States)

    Jia, Xiaojuan; Bi, Yuhai; Li, Jing; Xie, Qing; Yang, Hanchun; Liu, Wenjun

    2015-05-27

    Porcine reproductive and respiratory syndrome (PRRS) has caused large economic losses in the swine industry in recent years. Current PRRS vaccines fail to effectively prevent and control this disease. Consequently, there is a need to develop new antiviral strategies. MicroRNAs play critical roles in intricate host-pathogen interaction networks, but the involvement of miRNAs during PRRS virus (PRRSV) infection is not well understood. In this study, pretreatment with miR-26a induced a significant inhibition of PRRSV replication and remission of the cytopathic effect in MARC-145 cells, and this antiviral effect was sustained for at least 120 h. Luciferase reporter analysis showed that the PRRSV genome was not the target of miRNA-26a. Instead, RNA-seq analysis demonstrated that miR-26a significantly up-regulated innate anti-viral responses, including activating the type I interferon (IFN) signaling pathway and promoting the production of IFN-stimulated genes. These findings suggest that delivery of miR-26a may provide a potential strategy for anti-PRRSV therapies.

  14. High levels of adherence and viral suppression in a nationally representative sample of HIV-infected adults on antiretroviral therapy for 6, 12 and 18 months in Rwanda.

    Directory of Open Access Journals (Sweden)

    Batya Elul

    Full Text Available BACKGROUND: Generalizable data are needed on the magnitude and determinants of adherence and virological suppression among patients on antiretroviral therapy (ART in Africa. METHODS: We conducted a cross-sectional survey with chart abstraction, patient interviews and site assessments in a nationally representative sample of adults on ART for 6, 12 and 18 months at 20 sites in Rwanda. Adherence was assessed using 3- and 30-day patient recall. A systematically selected sub-sample had viral load (VL measurements. Multivariable logistic regression examined predictors of non-perfect (40 copies/ml. RESULTS: Overall, 1,417 adults were interviewed and 837 had VL measures. Ninety-four percent and 78% reported perfect adherence for the last 3 and 30 days, respectively. Eighty-three percent had undetectable VL. In adjusted models, characteristics independently associated with higher odds of non-perfect 30-day adherence were: being on ART for 18 months (vs. 6 months; younger age; reporting severe (vs. no or few side effects in the prior 30 days; having no documentation of CD4 cell count at ART initiation (vs. having a CD4 cell count of <200 cells/µL; alcohol use; and attending sites which initiated ART services in 2003-2004 and 2005 (vs. 2006-2007; sites with ≥600 (vs. <600 patients on ART; or sites with peer educators. Participation in an association for people living with HIV/AIDS; and receiving care at sites which regularly conduct home-visits were independently associated with lower odds of non-adherence. Higher odds of having a detectable VL were observed among patients at sites with peer educators. Being female; participating in an association for PLWHA; and using a reminder tool were independently associated with lower odds of having detectable VL. CONCLUSIONS: High levels of adherence and viral suppression were observed in the Rwandan national ART program, and associated with potentially modifiable factors.

  15. Condomless Sex Among Virally Suppressed Women With HIV With Regular HIV-Serodiscordant Sexual Partners in the Era of Treatment as Prevention.

    Science.gov (United States)

    Patterson, Sophie; Carter, Allison; Nicholson, Valerie; Webster, Kath; Ding, Erin; Kestler, Mary; Ogilvie, Gina; de Pokomandy, Alexandra; Loutfy, Mona; Kaida, Angela

    2017-12-01

    Sexual HIV transmission does not occur with sustained undetectable viral load (VL) on antiretroviral therapy (ART). Awareness of ART prevention benefits and its influence on condom use among women with HIV (WWH) remain unexplored. We estimated prevalence and correlates of condomless sex with regular HIV-serodiscordant partners among WWH with undetectable VL on ART. We used baseline questionnaire data from the community-based longitudinal Canadian HIV Women's Sexual and Reproductive Health Cohort Study (CHIWOS). We included WWH self-reporting vaginal/anal sex with ≥1 HIV-negative/unknown status regular partner within 6 months, and undetectable VL (prevention benefits. Logistic regression identified factors independently associated with condomless sex. Of 271 participants (19% of the CHIWOS cohort), median age was 41 (interquartile range: 34-47), 51% were in a relationship, 55% reported condomless sex, and 75% were aware of ART prevention benefits. Among women aware, 63% reported condomless sex compared with 32% of women not aware (P prevention benefits (adjusted odds ratio: 4.08; 95% confidence interval: 2.04 to 8.16), white ethnicity, ≥high-school education, residing in British Columbia, and being in a relationship. Virally suppressed women aware of ART prevention benefits had 4-fold greater odds of condomless sex. Advancing safer sex discussions beyond condoms is critical to support women in regular serodiscordant partnerships to realize options for safe and satisfying sexuality in the Treatment-as-Prevention era.

  16. Model of OSBP-Mediated Cholesterol Supply to Aichi Virus RNA Replication Sites Involving Protein-Protein Interactions among Viral Proteins, ACBD3, OSBP, VAP-A/B, and SAC1.

    Science.gov (United States)

    Ishikawa-Sasaki, Kumiko; Nagashima, Shigeo; Taniguchi, Koki; Sasaki, Jun

    2018-04-15

    Positive-strand RNA viruses, including picornaviruses, utilize cellular machinery for genome replication. Previously, we reported that each of the 2B, 2BC, 2C, 3A, and 3AB proteins of Aichi virus (AiV), a picornavirus, forms a complex with the Golgi apparatus protein ACBD3 and phosphatidylinositol 4-kinase IIIβ (PI4KB) at viral RNA replication sites (replication organelles [ROs]), enhancing PI4KB-dependent phosphatidylinositol 4-phosphate (PI4P) production. Here, we demonstrate AiV hijacking of the cellular cholesterol transport system involving oxysterol-binding protein (OSBP), a PI4P-binding cholesterol transfer protein. AiV RNA replication was inhibited by silencing cellular proteins known to be components of this pathway, OSBP, the ER membrane proteins VAPA and VAPB (VAP-A/B), the PI4P-phosphatase SAC1, and PI-transfer protein β. OSBP, VAP-A/B, and SAC1 were present at RNA replication sites. We also found various previously unknown interactions among the AiV proteins (2B, 2BC, 2C, 3A, and 3AB), ACBD3, OSBP, VAP-A/B, and SAC1, and the interactions were suggested to be involved in recruiting the component proteins to AiV ROs. Importantly, the OSBP-2B interaction enabled PI4P-independent recruitment of OSBP to AiV ROs, indicating preferential recruitment of OSBP among PI4P-binding proteins. Protein-protein interaction-based OSBP recruitment has not been reported for other picornaviruses. Cholesterol was accumulated at AiV ROs, and inhibition of OSBP-mediated cholesterol transfer impaired cholesterol accumulation and AiV RNA replication. Electron microscopy showed that AiV-induced vesicle-like structures were close to ER membranes. Altogether, we conclude that AiV directly recruits the cholesterol transport machinery through protein-protein interactions, resulting in formation of membrane contact sites between the ER and AiV ROs and cholesterol supply to the ROs. IMPORTANCE Positive-strand RNA viruses utilize host pathways to modulate the lipid composition of

  17. Transmissible Gastroenteritis Coronavirus Genome Packaging Signal Is Located at the 5′ End of the Genome and Promotes Viral RNA Incorporation into Virions in a Replication-Independent Process

    Science.gov (United States)

    Morales, Lucia; Mateos-Gomez, Pedro A.; Capiscol, Carmen; del Palacio, Lorena; Sola, Isabel

    2013-01-01

    Preferential RNA packaging in coronaviruses involves the recognition of viral genomic RNA, a crucial process for viral particle morphogenesis mediated by RNA-specific sequences, known as packaging signals. An essential packaging signal component of transmissible gastroenteritis coronavirus (TGEV) has been further delimited to the first 598 nucleotides (nt) from the 5′ end of its RNA genome, by using recombinant viruses transcribing subgenomic mRNA that included potential packaging signals. The integrity of the entire sequence domain was necessary because deletion of any of the five structural motifs defined within this region abrogated specific packaging of this viral RNA. One of these RNA motifs was the stem-loop SL5, a highly conserved motif in coronaviruses located at nucleotide positions 106 to 136. Partial deletion or point mutations within this motif also abrogated packaging. Using TGEV-derived defective minigenomes replicated in trans by a helper virus, we have shown that TGEV RNA packaging is a replication-independent process. Furthermore, the last 494 nt of the genomic 3′ end were not essential for packaging, although this region increased packaging efficiency. TGEV RNA sequences identified as necessary for viral genome packaging were not sufficient to direct packaging of a heterologous sequence derived from the green fluorescent protein gene. These results indicated that TGEV genome packaging is a complex process involving many factors in addition to the identified RNA packaging signal. The identification of well-defined RNA motifs within the TGEV RNA genome that are essential for packaging will be useful for designing packaging-deficient biosafe coronavirus-derived vectors and providing new targets for antiviral therapies. PMID:23966403

  18. Reduction of hepatitis C virus NS5A hyperphosphorylation by selective inhibition of cellular kinases activates viral RNA replication in cell culture.

    Science.gov (United States)

    Neddermann, Petra; Quintavalle, Manuela; Di Pietro, Chiara; Clementi, Angelica; Cerretani, Mauro; Altamura, Sergio; Bartholomew, Linda; De Francesco, Raffaele

    2004-12-01

    Efficient replication of hepatitis C virus (HCV) subgenomic RNA in cell culture requires the introduction of adaptive mutations. In this report we describe a system which enables efficient replication of the Con1 subgenomic replicon in Huh7 cells without the introduction of adaptive mutations. The starting hypothesis was that high amounts of the NS5A hyperphosphorylated form, p58, inhibit replication and that reduction of p58 by inhibition of specific kinase(s) below a certain threshold enables HCV replication. Upon screening of a panel of kinase inhibitors, we selected three compounds which inhibited NS5A phosphorylation in vitro and the formation of NS5A p58 in cell culture. Cells, transfected with the HCV Con1 wild-type sequence, support HCV RNA replication upon addition of any of the three compounds. The effect of the kinase inhibitors was found to be synergistic with coadaptive mutations in NS3. This is the first direct demonstration that the presence of high amounts of NS5A-p58 causes inhibition of HCV RNA replication in cell culture and that this inhibition can be relieved by kinase inhibitors.

  19. The utility of siRNA transcripts produced by RNA polymerase i in down regulating viral gene expression and replication of negative- and positive-strand RNA viruses

    International Nuclear Information System (INIS)

    McCown, Matthew; Diamond, Michael S.; Pekosz, Andrew

    2003-01-01

    Short interfering double-stranded RNAs (siRNAs) expressed under the control of an RNA polymerase I promoter system were used to target gene expression of influenza A and West Nile virus. Decreased RNA and protein expression was induced in a sequence-specific manner--reducing sequence complementarity from 21 to 17 nucleotides abrogated the siRNA effect. Reduced M 2 expression resulted in a decrease in total and infectious influenza A virus production. WNV protein expression, genomic RNA, and infectious virus production were all dramatically reduced by siRNAs targeting two distinct viral sequences. The data demonstrate the utility of plasmid-driven siRNAs in regulating the expression of single viral genes, global viral gene expression, as a potential antiviral treatment, and as a genetic tool for viruses whose genomes are difficult to manipulate

  20. The virion-associated open reading frame 49 of murine gammaherpesvirus 68 promotes viral replication both in vitro and in vivo as a derepressor of RTA.

    Science.gov (United States)

    Noh, Cheol-Woo; Cho, Hye-Jeong; Kang, Hye-Ri; Jin, Hyun Yong; Lee, Shaoying; Deng, Hongyu; Wu, Ting-Ting; Arumugaswami, Vaithilingaraja; Sun, Ren; Song, Moon Jung

    2012-01-01

    Replication and transcription activator (RTA), an immediate-early gene, is a key molecular switch to evoke lytic replication of gammaherpesviruses. Open reading frame 49 (ORF49) is conserved among gammaherpesviruses and shown to cooperate with RTA in regulating virus lytic replication. Here we show a molecular mechanism and in vivo functions of murine gammaherpesvirus 68 (MHV-68 or γHV-68) ORF49. MHV-68 ORF49 was transcribed and translated as a late gene. The ORF49 protein was associated with a virion, interacting with the ORF64 large tegument protein and the ORF25 capsid protein. Moreover, ORF49 directly bound to RTA and its negative cellular regulator, poly(ADP-ribose) polymerase-1 (PARP-1), and disrupted the interactions of RTA and PARP-1. Productive replication of an ORF49-deficient mutant virus (49S) was attenuated in vivo as well as in vitro. Likewise, latent infection was also impaired in the spleen of 49S-infected mice. Taken together, our results suggest that the virion-associated ORF49 protein may promote virus replication both in vitro and in vivo by providing an optimal environment in the early phase of virus infection as a derepressor of RTA.

  1. DNA replication and cancer

    DEFF Research Database (Denmark)

    Boyer, Anne-Sophie; Walter, David; Sørensen, Claus Storgaard

    2016-01-01

    A dividing cell has to duplicate its DNA precisely once during the cell cycle to preserve genome integrity avoiding the accumulation of genetic aberrations that promote diseases such as cancer. A large number of endogenous impacts can challenge DNA replication and cells harbor a battery of pathways...... to promote genome integrity during DNA replication. This includes suppressing new replication origin firing, stabilization of replicating forks, and the safe restart of forks to prevent any loss of genetic information. Here, we describe mechanisms by which oncogenes can interfere with DNA replication thereby...... causing DNA replication stress and genome instability. Further, we describe cellular and systemic responses to these insults with a focus on DNA replication restart pathways. Finally, we discuss the therapeutic potential of exploiting intrinsic replicative stress in cancer cells for targeted therapy....

  2. Viral suppression and adherence among HIV-infected children and adolescents on antiretroviral therapy: results of a multicenter study

    Directory of Open Access Journals (Sweden)

    Maria L.S. Cruz

    2014-12-01

    Full Text Available OBJECTIVE: To evaluate treatment adherence among perinatally-infected pediatric human immunodeficiency virus (HIV patients followed in pediatric centers in Brazil. METHODS: This was a cross-sectional multicenter study. Medical records were reviewed and adherence scale, assessment of caregivers' quality of life (WHOQOL-BREF, anxiety, depression, and alcohol/substances use/abuse were assessed. Outcomes included self-reported 100% adherence in the last three days and HIV viral load (VL < 50 copies/mL. Statistical analyses included contingency tables and respective statistics, and multivariable logistic regression. RESULTS: 260 subjects were enrolled: 78% children and 22% adolescents; 93% of caregivers for the children and 77% of adolescents reported 100% adherence; 57% of children and 49% of adolescents had VL < 50 copies/mL. In the univariate analyses, HIV diagnosis for screening due to maternal infection, lower caregiver scores for anxiety, and higher scores in physical and psychological domains of WHOQOL-BREF were associated with 100% adherence. Shorter intervals between pharmacy visits were associated with VL < 50 copies/mL (p ≤ 0.01. Multivariable regression demonstrated that caregivers who did not abuse alcohol/other drugs (OR = 0.49; 95% CI: 0.27-0.89 and median interval between pharmacy visits < 33 days (OR = 0.97; 95% CI: 0.95-0.98 were independently associated with VL < 50 copies/mL; whereas lower caregiver scores for anxiety (OR = 2.57; 95% CI: 1.27-5.19 and children's HIV diagnosis for screening due to maternal infection (OR = 2.25; 95% CI: 1.12-4.50 were found to be independently associated with 100% adherence. CONCLUSIONS: Pediatric HIV programs should perform routine assessment of caregivers' quality of life, and anxiety and depression symptoms. In this setting, pharmacy records are essential to help identify less-than-optimal adherence.

  3. Viral suppression and adherence among HIV-infected children and adolescents on antiretroviral therapy: results of a multicenter study.

    Science.gov (United States)

    Cruz, Maria L S; Cardoso, Claudete A A; Darmont, Mariana Q; Souza, Edvaldo; Andrade, Solange D; D'Al Fabbro, Marcia M; Fonseca, Rosana; Bellido, Jaime G; Monteiro, Simone S; Bastos, Francisco I

    2014-01-01

    To evaluate treatment adherence among perinatally-infected pediatric human immunodeficiency virus (HIV) patients followed in pediatric centers in Brazil. This was a cross-sectional multicenter study. Medical records were reviewed and adherence scale, assessment of caregivers' quality of life (WHOQOL-BREF), anxiety, depression, and alcohol/substances use/abuse were assessed. Outcomes included self-reported 100% adherence in the last three days and HIV viral load (VL)Statistical analyses included contingency tables and respective statistics, and multivariable logistic regression. 260 subjects were enrolled: 78% children and 22% adolescents; 93% of caregivers for the children and 77% of adolescents reported 100% adherence; 57% of children and 49% of adolescents had VLpsychological domains of WHOQOL-BREF were associated with 100% adherence. Shorter intervals between pharmacy visits were associated with VL<50 copies/mL (p ≤ 0.01). Multivariable regression demonstrated that caregivers who did not abuse alcohol/other drugs (OR=0.49; 95% CI: 0.27-0.89) and median interval between pharmacy visits<33 days (OR=0.97; 95% CI: 0.95-0.98) were independently associated with VL<50 copies/mL; whereas lower caregiver scores for anxiety (OR=2.57; 95% CI: 1.27-5.19) and children's HIV diagnosis for screening due to maternal infection (OR=2.25; 95% CI: 1.12-4.50) were found to be independently associated with 100% adherence. Pediatric HIV programs should perform routine assessment of caregivers' quality of life, and anxiety and depression symptoms. In this setting, pharmacy records are essential to help identify less-than-optimal adherence. Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  4. Transcriptional profiling reveals molecular signatures associated with HIV permissiveness in Th1Th17 cells and identifies Peroxisome Proliferator-Activated Receptor Gamma as an intrinsic negative regulator of viral replication

    Science.gov (United States)

    2013-01-01

    Background We previously demonstrated that primary Th1Th17 cells are highly permissive to HIV-1, whereas Th1 cells are relatively resistant. Molecular mechanisms underlying these differences remain unknown. Results Exposure to replication competent and single-round VSV-G pseudotyped HIV strains provide evidence that superior HIV replication in Th1Th17 vs. Th1 cells was regulated by mechanisms located at entry and post-entry levels. Genome-wide transcriptional profiling identified transcripts upregulated (n = 264) and downregulated (n = 235) in Th1Th17 vs. Th1 cells (p-value Th17 (nuclear receptors, trafficking, p38/MAPK, NF-κB, p53/Ras, IL-23) vs. Th1 cells (proteasome, interferon α/β). Differentially expressed genes were classified into biological categories using Gene Ontology. Th1Th17 cells expressed typical Th17 markers (IL-17A/F, IL-22, CCL20, RORC, IL-26, IL-23R, CCR6) and transcripts functionally linked to regulating cell trafficking (CEACAM1, MCAM), activation (CD28, CD40LG, TNFSF13B, TNFSF25, PTPN13, MAP3K4, LTB, CTSH), transcription (PPARγ, RUNX1, ATF5, ARNTL), apoptosis (FASLG), and HIV infection (CXCR6, FURIN). Differential expression of CXCR6, PPARγ, ARNTL, PTPN13, MAP3K4, CTSH, SERPINB6, PTK2, and ISG20 was validated by RT-PCR, flow cytometry and/or confocal microscopy. The nuclear receptor PPARγ was preferentially expressed by Th1Th17 cells. PPARγ RNA interference significantly increased HIV replication at levels post-entry and prior HIV-DNA integration. Finally, the activation of PPARγ pathway via the agonist Rosiglitazone induced the nuclear translocation of PPARγ and a robust inhibition of viral replication. Conclusions Thus, transcriptional profiling in Th1Th17 vs. Th1 cells demonstrated that HIV permissiveness is associated with a superior state of cellular activation and limited antiviral properties and identified PPARγ as an intrinsic negative regulator of viral replication. Therefore, triggering PPARγ pathway via non

  5. Modification of picornavirus genomic RNA using 'click' chemistry shows that unlinking of the VPg peptide is dispensable for translation and replication of the incoming viral RNA

    NARCIS (Netherlands)

    Langereis, Martijn A|info:eu-repo/dai/nl/304823597; Feng, Qian; Nelissen, Frank H T; Virgen-Slane, Richard; van der Heden van Noort, Gerbrand J; Maciejewski, Sonia; Filippov, Dmitri V; Semler, Bert L; van Delft, Floris L; van Kuppeveld, Frank J M|info:eu-repo/dai/nl/156614723

    Picornaviruses constitute a large group of viruses comprising medically and economically important pathogens such as poliovirus, coxsackievirus, rhinovirus, enterovirus 71 and foot-and-mouth disease virus. A unique characteristic of these viruses is the use of a viral peptide (VPg) as primer for

  6. Conserved retinoblastoma protein-binding motif in human cytomegalovirus UL97 kinase minimally impacts viral replication but affects susceptibility to maribavir

    Directory of Open Access Journals (Sweden)

    Chou Sunwen

    2009-01-01

    Full Text Available Abstract The UL97 kinase has been shown to phosphorylate and inactivate the retinoblastoma protein (Rb and has three consensus Rb-binding motifs that might contribute to this activity. Recombinant viruses containing mutations in the Rb-binding motifs generally replicated well in human foreskin fibroblasts with only a slight delay in replication kinetics. Their susceptibility to the specific UL97 kinase inhibitor, maribavir, was also examined. Mutation of the amino terminal motif, which is involved in the inactivation of Rb, also renders the virus hypersensitive to the drug and suggests that the motif may play a role in its mechanism of action.

  7. Twelve-Month Antiretroviral Therapy Suppresses Plasma and Genital Viral Loads but Fails to Alter Genital Levels of Cytokines, in a Cohort of HIV-Infected Rwandan Women.

    Directory of Open Access Journals (Sweden)

    Pascale Ondoa

    Full Text Available Genital viral load (GVL is the main determinant of sexual transmission of human immune-deficiency virus (HIV. The effect of antiretroviral therapy (ART on local cervico-vaginal immunological factors associated with GVL is poorly described. We aimed to identify the risk factors of detectable GVL, and the impact of ART on HIV genital shedding and its correlates in a cohort of HIV-infected women, attending HIV care in Kigali, Rwanda.All participants were evaluated for GVL, plasma viral load (PVL, CD4 count, various sexually-transmitted infections (STIs at baseline and at month 12. Genital concentration of 19 cytokines and mRNA expression of APOBEC3G and BST2, two host HIV restriction factors, were evaluated at baseline in all participants. Cytokine levels were re-assessed at month 12 only in participants eligible for ART at baseline. Risk factors of GVL ≥ 40 copies/mL at baseline and month 12 were assessed using logistic regression. Effect of 12-month ART on various local and systemic immunological parameters was examined using a paired t-test and McNemar as appropriate.96 of the 247 women enrolled in the study were eligible for ART. After 12 months of ART, PVL and GVL decreased to undetectable level in respectively 74 and 88% of treated participants. ART did not affect cytokine levels. HIV genital shedding occurred only when PVL was detectable. At baseline, GVL was independently associated with IL-1β after controlling for PVL, age and N. gonorrhea infection (95% CI 1.32-2.15 and at month 12 with MIP-1β (95% CI 0.96-21.32 after controlling for baseline GVL, PVL and month 12 IL-8.Suppressive ART does not necessarily reduce genital level of immune activation. Minimizing all conditions favoring genital inflammation, including active detection and treatment of STIs, might reduce the risk of HIV transmission as supplement to the provision of potent ART.

  8. Novel use of surveillance data to detect HIV-infected persons with sustained high viral load and durable virologic suppression in New York City.

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    Arpi S Terzian

    Full Text Available Monitoring of the uptake and efficacy of ART in a population often relies on cross-sectional data, providing limited information that could be used to design specific targeted intervention programs. Using repeated measures of viral load (VL surveillance data, we aimed to estimate and characterize the proportion of persons living with HIV/AIDS (PLWHA in New York City (NYC with sustained high VL (SHVL and durably suppressed VL (DSVL.Retrospective cohort study of all persons reported to the NYC HIV Surveillance Registry who were alive and ≥12 years old by the end of 2005 and who had ≥2 VL tests in 2006 and 2007. SHVL and DSVL were defined as PLWHA with 2 consecutive VLs ≥100,000 copies/mL and PLWHA with all VLs ≤400 copies/mL, respectively. Logistic regression models using generalized estimating equations were used to model the association between SHVL and covariates. There were 56,836 PLWHA, of whom 7% had SHVL and 38% had DSVL. Compared to those without SHVL, persons with SHVL were more likely to be younger, black and have injection drug use (IDU risk. PLWHA with SHVL were more likely to die by 2007 and be younger by nearly ten years, on average.Nearly 60% of PLWHA in 2005 had multiple VLs, of whom almost 40% had DSVL, suggesting successful ART uptake. A small proportion had SHVL, representing groups known to have suboptimal engagement in care. This group should be targeted for additional outreach to reduce morbidity and secondary transmission. Measures based on longitudinal analyses of surveillance data in conjunction with cross-sectional measures such as community viral load represent more precise and powerful tools for monitoring ART effectiveness and potential impact on disease transmission than cross-sectional measures alone.

  9. The Combination of the R263K and T66I Resistance Substitutions in HIV-1 Integrase Is Incompatible with High-Level Viral Replication and the Development of High-Level Drug Resistance.

    Science.gov (United States)

    Liang, Jiaming; Mesplède, Thibault; Oliveira, Maureen; Anstett, Kaitlin; Wainberg, Mark A

    2015-11-01

    The R263K substitution in integrase has been selected in tissue culture with dolutegravir (DTG) and has been reported for several treatment-experienced individuals receiving DTG as part of salvage therapy. The R263K substitution seems to be incompatible with the presence of common resistance mutations associated with raltegravir (RAL), a different integrase strand transfer inhibitor (INSTI). T66I is a substitution that is common in individuals who have developed resistance against a different INSTI termed elvitegravir (EVG), but it is not known whether these two mutations might be compatible in the context of resistance against DTG or what impact the combination of these substitutions might have on resistance against INSTIs. E138K is a common secondary substitution observed with various primary resistance substitutions in RAL- and EVG-treated individuals. Viral infectivity, replicative capacity, and resistance against INSTIs were measured in cell-based assays. Strand transfer and 3' processing activities were measured biochemically. The combination of the R263K and T66I substitutions decreased HIV-1 infectivity, replicative capacity, and strand transfer activity. The addition of the E138K substitution partially compensated for these deficits and resulted in high levels of resistance against EVG but not against DTG or RAL. These findings suggest that the presence of the T66I substitution will not compromise the activity of DTG and may also help to prevent the additional generation of the R263K mutation. Our observations support the use of DTG in second-line therapy for individuals who experience treatment failure with EVG due to the T66I substitution. The integrase strand transfer inhibitors (INSTIs) elvitegravir and dolutegravir are newly developed inhibitors against human immunodeficiency virus type 1 (HIV-1). HIV drug-resistant mutations in integrase that can arise in individuals treated with elvitegravir commonly include the T66I substitution, whereas R263K is a

  10. Genomic polymorphism of the pandemic A (H1N1 influenza viruses correlates with viral replication, virulence, and pathogenicity in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Lili Xu

    Full Text Available The novel pandemic A (H1N1 virus was first identified in Mexico in April 2009 and quickly spread worldwide. Like all influenzas, the H1N1 strain-specific properties of replication, virulence, and pathogenicity are a result of the particular genomic sequence and concerted expression of multiple genes. Thus, specific mutations may support increased virulence and may be useful as biomarkers of potential threat to human health. We performed comparative genomic analysis of ten strains of the 2009 pandemic A (H1N1 influenza viruses to determine whether genotypes associated with clinical phenotypes, which ranged from mild to severe illness and up to lethal. Virus replication capacity was tested for each strain in vitro using cultured epithelial cells, while virulence and pathogenicity were investigated in vivo using the BALB/c mouse model. The results indicated that A/Sichuan/1/2009 strain had significantly higher replication ability and virulence than the other strains, and five unique non-synonymous mutations were identified in important gene-encoding sequences. These mutations led to amino acid substitutions in HA (L32I, PA (A343T, PB1 (K353R and T566A, and PB2 (T471M, and may be critical molecular determinants for replication, virulence, and pathogenicity. Our results suggested that the replication capacity in vitro and virulence in vivo of the 2009 pandemic A (H1N1 viruses were not associated with the clinical phenotypes. This study offers new insights into the transmission and evolution of the 2009 pandemic A (H1N1 virus.

  11. CD4 cell count and the risk of AIDS or death in HIV-Infected adults on combination antiretroviral therapy with a suppressed viral load: a longitudinal cohort study from COHERE.

    Directory of Open Access Journals (Sweden)

    Jim Young

    Full Text Available Most adults infected with HIV achieve viral suppression within a year of starting combination antiretroviral therapy (cART. It is important to understand the risk of AIDS events or death for patients with a suppressed viral load.Using data from the Collaboration of Observational HIV Epidemiological Research Europe (2010 merger, we assessed the risk of a new AIDS-defining event or death in successfully treated patients. We accumulated episodes of viral suppression for each patient while on cART, each episode beginning with the second of two consecutive plasma viral load measurements 500 copies/µl, the first of two consecutive measurements between 50-500 copies/µl, cART interruption or administrative censoring. We used stratified multivariate Cox models to estimate the association between time updated CD4 cell count and a new AIDS event or death or death alone. 75,336 patients contributed 104,265 suppression episodes and were suppressed while on cART for a median 2.7 years. The mortality rate was 4.8 per 1,000 years of viral suppression. A higher CD4 cell count was always associated with a reduced risk of a new AIDS event or death; with a hazard ratio per 100 cells/µl (95% CI of: 0.35 (0.30-0.40 for counts <200 cells/µl, 0.81 (0.71-0.92 for counts 200 to <350 cells/µl, 0.74 (0.66-0.83 for counts 350 to <500 cells/µl, and 0.96 (0.92-0.99 for counts ≥500 cells/µl. A higher CD4 cell count became even more beneficial over time for patients with CD4 cell counts <200 cells/µl.Despite the low mortality rate, the risk of a new AIDS event or death follows a CD4 cell count gradient in patients with viral suppression. A higher CD4 cell count was associated with the greatest benefit for patients with a CD4 cell count <200 cells/µl but still some slight benefit for those with a CD4 cell count ≥500 cells/µl.

  12. The Glycoprotein and the Matrix Protein of Rabies Virus Affect Pathogenicity by Regulating Viral Replication and Facilitating Cell-to-Cell Spread▿

    OpenAIRE

    Pulmanausahakul, Rojjanaporn; Li, Jianwei; Schnell, Matthias J.; Dietzschold, Bernhard

    2007-01-01

    While the glycoprotein (G) of rabies virus (RV) is known to play a predominant role in the pathogenesis of rabies, the function of the RV matrix protein (M) in RV pathogenicity is not completely clear. To further investigate the roles of these proteins in viral pathogenicity, we constructed chimeric recombinant viruses by exchanging the G and M genes of the attenuated SN strain with those of the highly pathogenic SB strain. Infection of mice with these chimeric viruses revealed a significant ...

  13. Replicative homeostasis II: Influence of polymerase fidelity on RNA virus quasispecies biology: Implications for immune recognition, viral autoimmunity and other "virus receptor" diseases

    OpenAIRE

    Sallie, Richard

    2005-01-01

    Abstract Much of the worlds' population is in active or imminent danger from established infectious pathogens, while sporadic and pandemic infections by these and emerging agents threaten everyone. RNA polymerases (RNApol) generate enormous genetic and consequent antigenic heterogeneity permitting both viruses and cellular pathogens to evade host defences. Thus, RNApol causes more morbidity and premature mortality than any other molecule. The extraordinary genetic heterogeneity defining viral...

  14. A novel class of anti-HIV agents with multiple copies of enfuvirtide enhances inhibition of viral replication and cellular transmission in vitro.

    Directory of Open Access Journals (Sweden)

    Chien-Hsing Chang

    Full Text Available We constructed novel HIV-1 fusion inhibitors that may overcome the current limitations of enfuvirtide, the first such therapeutic in this class. The three prototypes generated by the Dock-and-Lock (DNL technology to comprise four copies of enfuvirtide tethered site-specifically to the Fc end of different humanized monoclonal antibodies potently neutralize primary isolates (both R5-tropic and X4-tropic, as well as T-cell-adapted strains of HIV-1 in vitro. All three prototypes show EC(50 values in the subnanomolar range, which are 10- to 100-fold lower than enfuvirtide and attainable whether or not the constitutive antibody targets HIV-1. The potential of such conjugates to purge latently infected cells was also demonstrated in a cell-to-cell viral inhibition assay by measuring their efficacy to inhibit the spread of HIV-1(LAI from infected human peripheral blood mononuclear cells to Jurkat T cells over a period of 30 days following viral activation with 100 nM SAHA (suberoylanilide hydroxamic acid. The IgG-like half-life was not significantly different from that of the parental antibody, as shown by the mean serum concentration of one prototype in mice at 72 h. These encouraging results provide a rationale to develop further novel anti-HIV agents by coupling additional antibodies of interest with alternative HIV-inhibitors via recombinantly-produced, self-assembling, modules.

  15. Addition of E138K to R263K in HIV integrase increases resistance to dolutegravir, but fails to restore activity of the HIV integrase enzyme and viral replication capacity.

    Science.gov (United States)

    Mesplède, Thibault; Osman, Nathan; Wares, Melissa; Quashie, Peter K; Hassounah, Said; Anstett, Kaitlin; Han, Yingshan; Singhroy, Diane N; Wainberg, Mark A

    2014-10-01

    The results of several clinical trials suggest that the integrase inhibitor dolutegravir may be less prone than other drugs to the emergence of HIV drug resistance mutations in treatment-naive patients. We have shown that the R263K mutation commonly emerged during tissue culture selection studies with dolutegravir and conferred low levels of resistance to this drug while simultaneously diminishing both HIV replication capacity and integrase enzymatic activity. E138K has been identified as a secondary mutation for dolutegravir in selection studies and has also been observed as a secondary mutation in the clinic for the integrase inhibitors raltegravir and elvitegravir. We used biochemical cell-free strand-transfer assays and tissue culture assays to characterize the effects of the E138K/R263K combination of mutations on resistance to dolutegravir, integrase enzyme activity and HIV-1 replication capacity. We show here that the addition of the E138K substitution to R263K increased the resistance of HIV-1 to dolutegravir but failed to restore viral replication capacity, integrase strand-transfer activity and integration within cellular DNA. We also show that the addition of E138K to R263K did not increase the resistance to raltegravir or elvitegravir. The addition of the E138K substitution to R263K was also less detrimental to integrase strand-transfer activity and integration than a different secondary mutation at position H51Y that had also been selected in culture. The E138K substitution failed to restore the defect in viral replication capacity that is associated with R263K, confirming previous selection studies that failed to identify compensatory mutation(s) for the latter primary mutation. This study suggests that the R263K resistance pathway may represent an evolutionary dead end for HIV in treatment-naive individuals who are treated with dolutegravir and will need to be confirmed by the long-term use of dolutegravir in the clinic. © The Author 2014. Published

  16. Luteolin-7-O-Glucoside Present in Lettuce Extracts Inhibits Hepatitis B Surface Antigen Production and Viral Replication by Human Hepatoma Cells in Vitro

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    Xiao-Xian Cui

    2017-12-01

    Full Text Available Hepatitis B virus (HBV infection is endemic in Asia and chronic hepatitis B (CHB is a major public health issue worldwide. Current treatment strategies for CHB are not satisfactory as they induce a low rate of hepatitis B surface antigen (HBsAg loss. Extracts were prepared from lettuce hydroponically cultivated in solutions containing glycine or nitrate as nitrogen sources. The lettuce extracts exerted potent anti-HBV effects in HepG2 cell lines in vitro, including significant HBsAg inhibition, HBV replication and transcription inhibition, without exerting cytotoxic effects. When used in combination interferon-alpha 2b (IFNα-2b or lamivudine (3TC, the lettuce extracts synergistically inhibited HBsAg expression and HBV replication. By using differential metabolomics analysis, Luteolin-7-O-glucoside was identified and confirmed as a functional component of the lettuce extracts and exhibited similar anti-HBV activity as the lettuce extracts in vitro. The inhibition rate on HBsAg was up to 77.4%. Moreover, both the lettuce extracts and luteolin-7-O-glucoside functioned as organic antioxidants and, significantly attenuated HBV-induced intracellular reactive oxygen species (ROS accumulation. Luteolin-7-O-glucoside also normalized ROS-induced mitochondrial membrane potential damage, which suggests luteolin-7-O-glucoside inhibits HBsAg and HBV replication via a mechanism involving the mitochondria. Our findings suggest luteolin-7-O-glucoside may have potential value for clinical application in CHB and may enhance HBsAg and HBV clearance when used as a combination therapy.

  17. Simian virus 40 large T-antigen point mutants that are defective in viral DNA replication but competent in oncogenic transformation.

    OpenAIRE

    Manos, M M; Gluzman, Y

    1984-01-01

    The large T antigen of simian virus 40 (SV40) is a multifunctional protein that is essential in both the virus lytic cycle and the oncogenic transformation of cells by SV40. To investigate the role of the numerous biochemical and physiological activities of T antigen in the lytic and transformation processes, we have studied DNA replication-deficient, transformation-competent large T-antigen mutants. Here we describe the genetic and biochemical analyses of two such mutants, C2/SV40 and C11/SV...

  18. White matter structure alterations in HIV-1-infected men with sustained suppression of viraemia on treatment

    NARCIS (Netherlands)

    Su, Tanja; Caan, Matthan W. A.; Wit, Ferdinand W. N. M.; Schouten, Judith; Geurtsen, Gert J.; Cole, James H.; Sharp, David J.; Vos, Frans M.; Prins, Maria; Portegies, Peter; Reiss, Peter; Majoie, Charles B.

    2016-01-01

    Cognitive impairment is highly prevalent in HIV-1-infected (HIV+) patients, despite adequate suppression of viral replication by combination antiretroviral therapy (cART). Cerebral white matter structure alterations are often associated with cognitive impairment and have commonly been reported in

  19. Genetic determinants in HIV-1 Gag and Env V3 are related to viral response to combination antiretroviral therapy with a protease inhibitor.

    Science.gov (United States)

    Ho, Sarah K; Perez, Elena E; Rose, Stephanie L; Coman, Roxana M; Lowe, Amanda C; Hou, Wei; Ma, Changxing; Lawrence, Robert M; Dunn, Ben M; Sleasman, John W; Goodenow, Maureen M

    2009-08-24

    To identify novel viral determinants in HIV-1 protease, Gag, and envelope V3 that relate to outcomes to initial protease inhibitor-based antiretroviral therapy. A longitudinal cohort study of protease inhibitor-naive, HIV-infected individuals was designed to identify genetic variables in viral Gag and envelope sequences associated with response to antiretroviral therapy. Genetic and statistical models, including amino acid profiles, phylogenetic analyses, receiver operating characteristic analyses, and covariation analyses, were used to evaluate viral sequences and clinical variables from individuals who developed immune reconstitution with or without suppression of viral replication. Pretherapy chemokine (C-X-C motif) receptor 4-using V3 regions had significant associations with viral failure (P = 0.04). Amino acid residues in protease covaried with Gag residues, particularly in p7(NC), independent of cleavage sites. Pretherapy V3 charge combined with p6(Pol) and p2/p7(NC) cleavage site genotypes produced the best three-variable model to predict viral suppression in 88% of individuals. Combinations of baseline CD4 cell percentage with genetic determinants in Gag-protease predicted viral fitness in 100% of individuals who failed to suppress viral replication. Baseline genetic determinants in Gag p6(Pol) and p2/p7(NC), as well as envelope, provide novel combinations of biomarkers for predicting emergence of viral resistance to initial therapy regimens.

  20. Effect of ambient temperature on viral replication and serum antibody titers following administration of a commercial intranasal modified-live infectious bovine rhinotracheitis-parainfluenza-3 virus vaccine to beef cattle housed in high- and moderate-ambient temperature environments.

    Science.gov (United States)

    Grissett, Gretchen P; White, Brad J; Anderson, David E; Larson, Robert E; Miesner, Matt D

    2014-12-01

    To evaluate the effect of ambient temperature on viral replication and serum antibody titers following administration of an intranasal modified-live infectious bovine rhinotracheitis (IBR)-parainfluenza-3 (PI3) virus vaccine to beef calves housed in high- (> 32°C) and moderate- (21°C) ambient temperature environments. 28 calves (mean weight, 206.8 kg). Calves were randomly allocated to 4 treatment groups (housed outdoors during high ambient temperature with [HAT; n = 10] or without [HAC; 4] vaccination or housed indoors in a moderate ambient temperature with [MAT; 10] or without [MAC; 4] vaccination). Rectal and nasal mucosal temperatures were recorded every 2 hours from 8 AM to 8 PM on days 0 (vaccination) and 1. Nasal swab specimens were obtained on days 0 through 7 for virus isolation. Serum samples were collected on days 0, 7, 14, and 28 for determination of antibody titers. Mean rectal temperature did not differ among the treatment groups. Mean nasal temperature for the HAT group was significantly higher than that for the MAT group at 6, 24, 30, 32, and 38 hours after vaccination. Viable IBR virus was isolated from all vaccinated calves on days 1 through 6. Two weeks after vaccination, vaccinated calves had anti-IBR antibody titers that were significantly greater than those for unvaccinated calves. Mean anti-IBR antibody titers did not differ significantly between the HAT and MAT groups. Results indicated that, following vaccination with an intranasal modified-live IBR-PI3 virus vaccine, IBR viral replication and serum antibody titers did not differ significantly between calves housed in high- and moderate-ambient temperature environments.

  1. Effects of chloroquine on viral infections: an old drug against today's diseases?

    Science.gov (United States)

    Savarino, Andrea; Boelaert, Johan R; Cassone, Antonio; Majori, Giancarlo; Cauda, Roberto

    2003-11-01

    Chloroquine is a 9-aminoquinoline known since 1934. Apart from its well-known antimalarial effects, the drug has interesting biochemical properties that might be applied against some viral infections. Chloroquine exerts direct antiviral effects, inhibiting pH-dependent steps of the replication of several viruses including members of the flaviviruses, retroviruses, and coronaviruses. Its best-studied effects are those against HIV replication, which are being tested in clinical trials. Moreover, chloroquine has immunomodulatory effects, suppressing the production/release of tumour necrosis factor alpha and interleukin 6, which mediate the inflammatory complications of several viral diseases. We review the available information on the effects of chloroquine on viral infections, raising the question of whether this old drug may experience a revival in the clinical management of viral diseases such as AIDS and severe acute respiratory syndrome, which afflict mankind in the era of globalisation.

  2. Flock House virus subgenomic RNA3 is replicated and its replication correlates with transactivation of RNA2

    International Nuclear Information System (INIS)

    Eckerle, Lance D.; Albarino, Cesar G.; Ball, L. Andrew.

    2003-01-01

    The nodavirus Flock House virus has a bipartite genome composed of RNAs 1 and 2, which encode the catalytic component of the RNA-dependent RNA polymerase (RdRp) and the capsid protein precursor, respectively. In addition to catalyzing replication of the viral genome, the RdRp also transcribes from RNA1 a subgenomic RNA3, which is both required for and suppressed by RNA2 replication. Here, we show that in the absence of RNA1 replication, FHV RdRp replicated positive-sense RNA3 transcripts fully and copied negative-sense RNA3 transcripts into positive strands. The two nonstructural proteins encoded by RNA3 were dispensable for replication, but sequences in the 3'-terminal 58 nucleotides were required. RNA3 variants that failed to replicate also failed to transactivate RNA2. These results imply that RNA3 is naturally produced both by transcription from RNA1 and by subsequent RNA1-independent replication and that RNA3 replication may be necessary for transactivation of RNA2

  3. Enhancing patient navigation to improve intervention session attendance and viral load suppression of persons with HIV and substance use: a secondary post hoc analysis of the Project HOPE study.

    Science.gov (United States)

    Stitzer, Maxine; Matheson, Tim; Cunningham, Colin; Sorensen, James L; Feaster, Daniel J; Gooden, Lauren; Hammond, Alexis S; Fitzsimons, Heather; Metsch, Lisa R

    2017-06-27

    Interventions are needed to improve viral suppression rates among persons with HIV and substance use. A 3-arm randomized multi-site study (Metsch et al. in JAMA 316:156-70, 2016) was conducted to evaluate the effect on HIV outcomes of usual care referral to HIV and substance use services (N = 253) versus patient navigation delivered alone (PN: N = 266) or together with contingency management (PN + CM; N = 271) that provided financial incentives targeting potential behavioral mediators of viral load suppression. This secondary analysis evaluates the effects of financial incentives on attendance at PN sessions and the relationship between session attendance and viral load suppression at end of the intervention. Frequency of sessions attended was analyzed over time and by distribution of individual session attendance frequency (PN vs PN + CM). Percent virally suppressed (≤200 copies/mL) at 6 months was compared for low, medium and high rate attenders. In PN + CM a total of $220 could be earned for attendance at 11 PN sessions over the 6-month intervention with payments ranging from $10 to $30 under an escalating schedule. The majority (74%) of PN-only participants attended 6 or more sessions but only 28% attended 10 or more and 16% attended all eleven sessions. In contrast, 90% of PN + CM attended 6 or more visits, 69% attended 10 or more and 57% attended all eleven sessions (attendance distribution χ 2 [11] = 105.81; p Study results support use of attendance incentives to improve rates of contact between service providers and patients, particularly patients who are difficult to engage in care. Trial Registration clinicaltrials.govIdentifier: NCT01612169.

  4. Reported Church Attendance at the Time of Entry into HIV Care is Associated with Viral Load Suppression at 12 Months.

    Science.gov (United States)

    Van Wagoner, Nicholas; Elopre, Latesha; Westfall, Andrew O; Mugavero, Michael J; Turan, Janet; Hook, Edward W

    2016-08-01

    The Southeast has high rates of church attendance and HIV infection rates. We evaluated the relationship between church attendance and HIV viremia in a Southeastern US, HIV-infected cohort. Viremia (viral load ≥200 copies/ml) was analyzed 12 months after initiation of care. Univariate and multivariable logistic regression models were fit for variables potentially related to viremia. Of 382 patients, 74 % were virally suppressed at 12 months. Protective variables included church attendance (AOR 0.5; 95 % CI 0.2, 0.9), being on antiretroviral therapy (AOR 0.01; 95 % CI 0.004, 0.04), CD4(+) T lymphocyte count 200-350 cells/mm(3) at care entry (AOR 0.3; 95 % 0.1, 0.9), and education (AOR 0.5; 95 % CI 0.2, 0.9). Variables predicting viremia included black race (AOR 3.2; 95 % CI 1.4, 7.4) and selective disclosure of HIV status (AOR 2.7; 95 % CI 1.2, 5.6). Church attendance may provide needed support for patients entering HIV care for the first time. El Sur Este de los Estados Unidos tiene tasas altas de visitas a iglesias y de infección por VIH. Evaluamos la relación entre visitas a iglesias y viremia por VIH en una cohorte de pacientes infectados con VIH en el Sur Este de los EEUU. La viremia (carga viral ≥ 200 copias/ml) fue analizada a los 12 meses de iniciar el cuidado médico. Los modelos de regresión logística univariado y multivariado fueron ajustados para variables potencialmente relacionadas a viremia. De 382 pacientes, 75 % tuvieron supresión virológica a los 12 meses. Variables que ofrecieron protección fueron visitas a iglesias (AOR 0.5; IC95 % 0.2-0.9), recibir terapia antiretroviral (AOR 0.01; IC95 % 0.004,0.04), recuento de linfocitos T CD4 + 200-350 al iniciar cuidado médico (AOR 0.3; IC95 % 0.1,09), y educación (AOR 0.5; IC95 % 0.2,0.9). Las variables que predijeron viremia incluyeron raza negra (AOR 3.2; IC95 % 1.4,7.4) y la comunicación selectiva del diagnóstico de VIH a otras personas (AOR 2.7; 95 % IC 1

  5. Mode of transgene expression after fusion to early or late viral genes of a conditionally replicating adenovirus via an optimized internal ribosome entry site in vitro and in vivo

    International Nuclear Information System (INIS)

    Rivera, Angel A.; Wang Minghui; Suzuki, Kaori; Uil, Taco G.; Krasnykh, Victor; Curiel, David T.; Nettelbeck, Dirk M.

    2004-01-01

    The expression of therapeutic genes by oncolytic viruses is a promising strategy to improve viral oncolysis, to augment gene transfer compared with a nonreplicating adenoviral vector, or to combine virotherapy and gene therapy. Both the mode of transgene expression and the locale of transgene insertion into the virus genome critically determine the efficacy of this approach. We report here on the properties of oncolytic adenoviruses which contain the luciferase cDNA fused via an optimized internal ribosome entry site (IRES) to the immediate early adenoviral gene E1A (AdΔE1AIL), the early gene E2B (AdΔE2BIL), or the late fiber gene (AdΔfiberIL). These viruses showed distinct kinetics of transgene expression and luciferase activity. Early after infection, luciferase activities were lower for these viruses, especially for AdΔE2BIL, compared with nonreplicating AdTL, which contained the luciferase gene expressed from the strong CMV promoter. However, 6 days after infection, luciferase activities were approximately four (AdΔE1AIL) to six (AdΔfiberIL) orders of magnitude higher than for AdTL, reflecting virus replication and efficient transgene expression. Similar results were obtained in vivo after intratumoral injection of AdΔE2BIL, AdΔfiberIL, and AdTL. AdΔfiberIL and the parental virus, Ad5-Δ24, resulted in similar cytotoxicity, but AdΔE2BIL and AdΔE1AIL were slightly attenuated. Disruption of the expression of neighboring viral genes by insertion of the transgene was minimal for AdΔE2BIL and AdΔfiberIL, but substantial for AdΔE1AIL. Our observations suggest that insertion of IRES-transgene cassettes into viral transcription units is an attractive strategy for the development of armed oncolytic adenoviruses with defined kinetics and strength of transgene expression

  6. Conserved residues in the coiled-coil pocket of human immunodeficiency virus type 1 gp41 are essential for viral replication and interhelical interaction

    International Nuclear Information System (INIS)

    Mo Hongmei; Konstantinidis, Alex K.; Stewart, Kent D.; Dekhtyar, Tatyana; Ng, Teresa; Swift, Kerry; Matayoshi, Edmund D.; Kati, Warren; Kohlbrenner, William; Molla, Akhteruzzaman

    2004-01-01

    The human immunodeficiency virus type 1 (HIV-1) gp41 plays an important role in mediating the fusion of HIV with host cells. During the fusion process, three N-terminal helices and three C-terminal helices pack in an anti-parallel direction to form a six-helix bundle. X-ray crystallographic analysis of the gp41 core demonstrated that within each coiled-coil interface, there is a deep and large pocket, formed by a cluster of residues in the N-helix coiled-coil. In this report, we systematically analyzed the role of seven conserved residues that are either lining or packing this pocket on the infectivity and interhelical interaction using novel approaches. Our results show that residues L568, V570, W571, and K574 of the N-helix that are lining the side chain and right wall of the pocket are important for establishing a productive infection. Mutations V570A and W571A completely abolished replication, while replication of the L568A and K574A mutants was significantly attenuated relative to wild type. Similarly, residues W628, W631, and I635 of the C-helix that insert into the pocket are essential for infectivity. The impaired infectivity of these seven mutants is in part attributed to the loss in binding affinity of the interhelical interaction. Molecular modeling of the crystal structure of the coiled-coil further shows that alanine substitution of those residues disrupts the hydrophobic interaction between the N- and C-helix. These results suggest that the conserved residues in the coiled-coil domain play a key role in HIV infection and this coiled-coil pocket is a good target for development of inhibitors against HIV. In addition, our data indicate that the novel fluorescence polarization assay described in this study could be valuable in screening for inhibitors that block the interhelical interaction and HIV entry

  7. A selective barrier to horizontal gene transfer in the T4-type bacteriophages that has preserved a core genome with the viral replication and structural genes.

    Science.gov (United States)

    Filée, Jonathan; Bapteste, Eric; Susko, Edward; Krisch, H M

    2006-09-01

    Genomic analysis of bacteriophages frequently reveals a mosaic structure made up from modules that come from disparate sources. This fact has led to the general acceptance of the notion that rampant and promiscuous lateral gene transfer (LGT) plays a critical role in phage evolution. However, recent sequencing of a series of the T4-type phages has revealed that these large and complex genomes all share 2 substantial syntenous blocks of genes encoding the replication and virion structural genes. To analyze the pattern of inheritance of this core T4 genome, we compared the complete genome sequences of 16 T4-type phages. We identified a set of 24 genes present in all these T4-type genomes. Somewhat surprisingly, only one of these genes, that encodes for ribonucleotide reductase (NrdA), displayed evidence of LGT with the bacterial host. We test the congruence of the inheritance of the other 23 markers using heat map analyses and comparison of a reference topology with the 23 individual gene phylogenies. The vast majority of these core genes share a common evolutionary history. In contrast, analyses of all the noncore genes present in the same 16 genomes, located in the hyperplastic regions of the genome, show considerable evidence of frequent LGT. The similar evolution of the core replication and virion structural genes in the T4-type phage genomes suggests that, unlike the situation in many other phage groups, such portions of T4-type genome have been inherited as a block, without significant LGT, from a distant common ancestor. The preservation of the synteny of the core T4 genome could result from several factors acting in synergy, such as the constraints imposed by the sophisticated regulation of the transcription. Moreover, numerous and complex protein-protein interactions during virion morphogenesis could also impose a supplementary barrier against LGT. Finally, there may be some real evolutionary advantage to maintaining large regions of conserved sequence. Such

  8. Exon level transcriptomic profiling of HIV-1-infected CD4(+ T cells reveals virus-induced genes and host environment favorable for viral replication.

    Directory of Open Access Journals (Sweden)

    Michaël Imbeault

    Full Text Available HIV-1 is extremely specialized since, even amongst CD4(+ T lymphocytes (its major natural reservoir in peripheral blood, the virus productively infects only a small proportion of cells under an activated state. As the percentage of HIV-1-infected cells is very low, most studies have so far failed to capture the precise transcriptomic profile at the whole-genome scale of cells highly susceptible to virus infection. Using Affymetrix Exon array technology and a reporter virus allowing the magnetic isolation of HIV-1-infected cells, we describe the host cell factors most favorable for virus establishment and replication along with an overview of virus-induced changes in host gene expression occurring exclusively in target cells productively infected with HIV-1. We also establish that within a population of activated CD4(+ T cells, HIV-1 has no detectable effect on the transcriptome of uninfected bystander cells at early time points following infection. The data gathered in this study provides unique insights into the biology of HIV-1-infected CD4(+ T cells and identifies genes thought to play a determinant role in the interplay between the virus and its host. Furthermore, it provides the first catalogue of alternative splicing events found in primary human CD4(+ T cells productively infected with HIV-1.

  9. Class A scavenger receptor 1 (MSR1 restricts hepatitis C virus replication by mediating toll-like receptor 3 recognition of viral RNAs produced in neighboring cells.

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    Hiromichi Dansako

    Full Text Available Persistent infections with hepatitis C virus (HCV may result in life-threatening liver disease, including cirrhosis and cancer, and impose an important burden on human health. Understanding how the virus is capable of achieving persistence in the majority of those infected is thus an important goal. Although HCV has evolved multiple mechanisms to disrupt and block cellular signaling pathways involved in the induction of interferon (IFN responses, IFN-stimulated gene (ISG expression is typically prominent in the HCV-infected liver. Here, we show that Toll-like receptor 3 (TLR3 expressed within uninfected hepatocytes is capable of sensing infection in adjacent cells, initiating a local antiviral response that partially restricts HCV replication. We demonstrate that this is dependent upon the expression of class A scavenger receptor type 1 (MSR1. MSR1 binds extracellular dsRNA, mediating its endocytosis and transport toward the endosome where it is engaged by TLR3, thereby triggering IFN responses in both infected and uninfected cells. RNAi-mediated knockdown of MSR1 expression blocks TLR3 sensing of HCV in infected hepatocyte cultures, leading to increased cellular permissiveness to virus infection. Exogenous expression of Myc-MSR1 restores TLR3 signaling in MSR1-depleted cells with subsequent induction of an antiviral state. A series of conserved basic residues within the carboxy-terminus of the collagen superfamily domain of MSR1 are required for binding and transport of dsRNA, and likely facilitate acidification-dependent release of dsRNA at the site of TLR3 expression in the endosome. Our findings reveal MSR1 to be a critical component of a TLR3-mediated pattern recognition receptor response that exerts an antiviral state in both infected and uninfected hepatocytes, thereby limiting the impact of HCV proteins that disrupt IFN signaling in infected cells and restricting the spread of HCV within the liver.

  10. Selective expansion of viral variants following experimental transmission of a reconstituted feline immunodeficiency virus quasispecies.

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    Brian J Willett

    Full Text Available Following long-term infection with virus derived from the pathogenic GL8 molecular clone of feline immunodeficiency virus (FIV, a range of viral variants emerged with distinct modes of interaction with the viral receptors CD134 and CXCR4, and sensitivities to neutralizing antibodies. In order to assess whether this viral diversity would be maintained following subsequent transmission, a synthetic quasispecies was reconstituted comprising molecular clones bearing envs from six viral variants and its replicative capacity compared in vivo with a clonal preparation of the parent virus. Infection with either clonal (Group 1 or diverse (Group 2 challenge viruses, resulted in a reduction in CD4+ lymphocytes and an increase in CD8+ lymphocytes. Proviral loads were similar in both study groups, peaking by 10 weeks post-infection, a higher plateau (set-point being achieved and maintained in study Group 1. Marked differences in the ability of individual viral variants to replicate were noted in Group 2; those most similar to GL8 achieved higher viral loads while variants such as the chimaeras bearing the B14 and B28 Envs grew less well. The defective replication of these variants was not due to suppression by the humoral immune response as virus neutralising antibodies were not elicited within the study period. Similarly, although potent cellular immune responses were detect