Fierce competition between Toxoplasma and Chlamydia for host cell structures in dually infected cells.

Science.gov (United States)

Romano, Julia D; de Beaumont, Catherine; Carrasco, Jose A; Ehrenman, Karen; Bavoil, Patrik M; Coppens, Isabelle

2013-02-01

The prokaryote Chlamydia trachomatis and the protozoan Toxoplasma gondii, two obligate intracellular pathogens of humans, have evolved a similar modus operandi to colonize their host cell and salvage nutrients from organelles. In order to gain fundamental knowledge on the pathogenicity of these microorganisms, we have established a cell culture model whereby single fibroblasts are coinfected by C. trachomatis and T. gondii. We previously reported that the two pathogens compete for the same nutrient pools in coinfected cells and that Toxoplasma holds a significant competitive advantage over Chlamydia. Here we have expanded our coinfection studies by examining the respective abilities of Chlamydia and Toxoplasma to co-opt the host cytoskeleton and recruit organelles. We demonstrate that the two pathogen-containing vacuoles migrate independently to the host perinuclear region and rearrange the host microtubular network around each vacuole. However, Toxoplasma outcompetes Chlamydia to the host microtubule-organizing center to the detriment of the bacterium, which then shifts to a stress-induced persistent state. Solely in cells preinfected with Chlamydia, the centrosomes become associated with the chlamydial inclusion, while the Toxoplasma parasitophorous vacuole displays growth defects. Both pathogens fragment the host Golgi apparatus and recruit Golgi elements to retrieve sphingolipids. This study demonstrates that the productive infection by both Chlamydia and Toxoplasma depends on the capability of each pathogen to successfully adhere to a finely tuned developmental program that aims to remodel the host cell for the pathogen's benefit. In particular, this investigation emphasizes the essentiality of host organelle interception by intravacuolar pathogens to facilitate access to nutrients.

Membrane rafts: a potential gateway for bacterial entry into host cells.

Science.gov (United States)

Hartlova, Anetta; Cerveny, Lukas; Hubalek, Martin; Krocova, Zuzana; Stulik, Jiri

2010-04-01

Pathogenic bacteria have developed various mechanisms to evade host immune defense systems. Invasion of pathogenic bacteria requires interaction of the pathogen with host receptors, followed by activation of signal transduction pathways and rearrangement of the cytoskeleton to facilitate bacterial entry. Numerous bacteria exploit specialized plasma membrane microdomains, commonly called membrane rafts, which are rich in cholesterol, sphingolipids and a special set of signaling molecules which allow entry to host cells and establishment of a protected niche within the host. This review focuses on the current understanding of the raft hypothesis and the means by which pathogenic bacteria subvert membrane microdomains to promote infection.

Host-to-host variation of ecological interactions in polymicrobial infections

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Mukherjee, Sayak; Weimer, Kristin E.; Seok, Sang-Cheol; Ray, Will C.; Jayaprakash, C.; Vieland, Veronica J.; Swords, W. Edward; Das, Jayajit

2015-02-01

Host-to-host variability with respect to interactions between microorganisms and multicellular hosts are commonly observed in infection and in homeostasis. However, the majority of mechanistic models used to analyze host-microorganism relationships, as well as most of the ecological theories proposed to explain coevolution of hosts and microbes, are based on averages across a host population. By assuming that observed variations are random and independent, these models overlook the role of differences between hosts. Here, we analyze mechanisms underlying host-to-host variations of bacterial infection kinetics, using the well characterized experimental infection model of polymicrobial otitis media (OM) in chinchillas, in combination with population dynamic models and a maximum entropy (MaxEnt) based inference scheme. We find that the nature of the interactions between bacterial species critically regulates host-to-host variations in these interactions. Surprisingly, seemingly unrelated phenomena, such as the efficiency of individual bacterial species in utilizing nutrients for growth, and the microbe-specific host immune response, can become interdependent in a host population. The latter finding suggests a potential mechanism that could lead to selection of specific strains of bacterial species during the coevolution of the host immune response and the bacterial species.

Host-to-host variation of ecological interactions in polymicrobial infections.

Science.gov (United States)

Mukherjee, Sayak; Weimer, Kristin E; Seok, Sang-Cheol; Ray, Will C; Jayaprakash, C; Vieland, Veronica J; Swords, W Edward; Das, Jayajit

2014-12-04

Host-to-host variability with respect to interactions between microorganisms and multicellular hosts are commonly observed in infection and in homeostasis. However, the majority of mechanistic models used to analyze host-microorganism relationships, as well as most of the ecological theories proposed to explain coevolution of hosts and microbes, are based on averages across a host population. By assuming that observed variations are random and independent, these models overlook the role of differences between hosts. Here, we analyze mechanisms underlying host-to-host variations of bacterial infection kinetics, using the well characterized experimental infection model of polymicrobial otitis media (OM) in chinchillas, in combination with population dynamic models and a maximum entropy (MaxEnt) based inference scheme. We find that the nature of the interactions between bacterial species critically regulates host-to-host variations in these interactions. Surprisingly, seemingly unrelated phenomena, such as the efficiency of individual bacterial species in utilizing nutrients for growth, and the microbe-specific host immune response, can become interdependent in a host population. The latter finding suggests a potential mechanism that could lead to selection of specific strains of bacterial species during the coevolution of the host immune response and the bacterial species.

Genome-wide host responses against infectious laryngotracheitis virus vaccine infection in chicken embryo lung cells

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Lee Jeongyoon

2012-04-01

Full Text Available Abstract Background Infectious laryngotracheitis virus (ILTV; gallid herpesvirus 1 infection causes high mortality and huge economic losses in the poultry industry. To protect chickens against ILTV infection, chicken-embryo origin (CEO and tissue-culture origin (TCO vaccines have been used. However, the transmission of vaccine ILTV from vaccinated- to unvaccinated chickens can cause severe respiratory disease. Previously, host cell responses against virulent ILTV infections were determined by microarray analysis. In this study, a microarray analysis was performed to understand host-vaccine ILTV interactions at the host gene transcription level. Results The 44 K chicken oligo microarrays were used, and the results were compared to those found in virulent ILTV infection. Total RNAs extracted from vaccine ILTV infected chicken embryo lung cells at 1, 2, 3 and 4 days post infection (dpi, compared to 0 dpi, were subjected to microarray assay using the two color hybridization method. Data analysis using JMP Genomics 5.0 and the Ingenuity Pathway Analysis (IPA program showed that 213 differentially expressed genes could be grouped into a number of functional categories including tissue development, cellular growth and proliferation, cellular movement, and inflammatory responses. Moreover, 10 possible gene networks were created by the IPA program to show intermolecular connections. Interestingly, of 213 differentially expressed genes, BMP2, C8orf79, F10, and NPY were expressed distinctly in vaccine ILTV infection when compared to virulent ILTV infection. Conclusions Comprehensive knowledge of gene expression and biological functionalities of host factors during vaccine ILTV infection can provide insight into host cellular defense mechanisms compared to those of virulent ILTV.

Host-to-host variation of ecological interactions in polymicrobial infections

International Nuclear Information System (INIS)

Mukherjee, Sayak; Seok, Sang-Cheol; Ray, Will C; Jayaprakash, C; Vieland, Veronica J; Das, Jayajit; Weimer, Kristin E; Swords, W Edward

2015-01-01

Host-to-host variability with respect to interactions between microorganisms and multicellular hosts are commonly observed in infection and in homeostasis. However, the majority of mechanistic models used to analyze host–microorganism relationships, as well as most of the ecological theories proposed to explain coevolution of hosts and microbes, are based on averages across a host population. By assuming that observed variations are random and independent, these models overlook the role of differences between hosts. Here, we analyze mechanisms underlying host-to-host variations of bacterial infection kinetics, using the well characterized experimental infection model of polymicrobial otitis media (OM) in chinchillas, in combination with population dynamic models and a maximum entropy (MaxEnt) based inference scheme. We find that the nature of the interactions between bacterial species critically regulates host-to-host variations in these interactions. Surprisingly, seemingly unrelated phenomena, such as the efficiency of individual bacterial species in utilizing nutrients for growth, and the microbe-specific host immune response, can become interdependent in a host population. The latter finding suggests a potential mechanism that could lead to selection of specific strains of bacterial species during the coevolution of the host immune response and the bacterial species. (paper)

Human borna disease virus infection impacts host proteome and histone lysine acetylation in human oligodendroglia cells

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Liu, Xia [Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016 (China); Department of Neurology, The Fifth People' s Hospital of Shanghai, School of Medicine, Fudan University, Shanghai, 200240 (China); Zhao, Libo [Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016 (China); Department of Neurology, The Third People' s Hospital of Chongqing, 400014 (China); Yang, Yongtao [Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016 (China); Chongqing Key Laboratory of Neurobiology, Chongqing Medical University, Chongqing, 400016 (China); Institute of Neuroscience, Chongqing Medical University, Chongqing, 400016 (China); Bode, Liv [Bornavirus Research Group affiliated to the Free University of Berlin, Berlin (Germany); Huang, Hua [Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016 (China); Chongqing Key Laboratory of Neurobiology, Chongqing Medical University, Chongqing, 400016 (China); Institute of Neuroscience, Chongqing Medical University, Chongqing, 400016 (China); Liu, Chengyu [Chongqing Key Laboratory of Neurobiology, Chongqing Medical University, Chongqing, 400016 (China); Institute of Neuroscience, Chongqing Medical University, Chongqing, 400016 (China); Huang, Rongzhong [Department of Rehabilitative Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 400010 (China); Zhang, Liang [Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016 (China); Chongqing Key Laboratory of Neurobiology, Chongqing Medical University, Chongqing, 400016 (China); Institute of Neuroscience, Chongqing Medical University, Chongqing, 400016 (China); and others

2014-09-15

Background: Borna disease virus (BDV) replicates in the nucleus and establishes persistent infections in mammalian hosts. A human BDV strain was used to address the first time, how BDV infection impacts the proteome and histone lysine acetylation (Kac) of human oligodendroglial (OL) cells, thus allowing a better understanding of infection-driven pathophysiology in vitro. Methods: Proteome and histone lysine acetylation were profiled through stable isotope labeling for cell culture (SILAC)-based quantitative proteomics. The quantifiable proteome was annotated using bioinformatics. Histone acetylation changes were validated by biochemistry assays. Results: Post BDV infection, 4383 quantifiable differential proteins were identified and functionally annotated to metabolism pathways, immune response, DNA replication, DNA repair, and transcriptional regulation. Sixteen of the thirty identified Kac sites in core histones presented altered acetylation levels post infection. Conclusions: BDV infection using a human strain impacted the whole proteome and histone lysine acetylation in OL cells. - Highlights: • A human strain of BDV (BDV Hu-H1) was used to infect human oligodendroglial cells (OL cells). • This study is the first to reveal the host proteomic and histone Kac profiles in BDV-infected OL cells. • BDV infection affected the expression of many transcription factors and several HATs and HDACs.

Human borna disease virus infection impacts host proteome and histone lysine acetylation in human oligodendroglia cells

International Nuclear Information System (INIS)

Liu, Xia; Zhao, Libo; Yang, Yongtao; Bode, Liv; Huang, Hua; Liu, Chengyu; Huang, Rongzhong; Zhang, Liang

2014-01-01

Background: Borna disease virus (BDV) replicates in the nucleus and establishes persistent infections in mammalian hosts. A human BDV strain was used to address the first time, how BDV infection impacts the proteome and histone lysine acetylation (Kac) of human oligodendroglial (OL) cells, thus allowing a better understanding of infection-driven pathophysiology in vitro. Methods: Proteome and histone lysine acetylation were profiled through stable isotope labeling for cell culture (SILAC)-based quantitative proteomics. The quantifiable proteome was annotated using bioinformatics. Histone acetylation changes were validated by biochemistry assays. Results: Post BDV infection, 4383 quantifiable differential proteins were identified and functionally annotated to metabolism pathways, immune response, DNA replication, DNA repair, and transcriptional regulation. Sixteen of the thirty identified Kac sites in core histones presented altered acetylation levels post infection. Conclusions: BDV infection using a human strain impacted the whole proteome and histone lysine acetylation in OL cells. - Highlights: • A human strain of BDV (BDV Hu-H1) was used to infect human oligodendroglial cells (OL cells). • This study is the first to reveal the host proteomic and histone Kac profiles in BDV-infected OL cells. • BDV infection affected the expression of many transcription factors and several HATs and HDACs

Selective alterations of the host cell architecture upon infection with parvovirus minute virus of mice

International Nuclear Information System (INIS)

Nueesch, Juerg P.F.; Lachmann, Sylvie; Rommelaere, Jean

2005-01-01

During a productive infection, the prototype strain of parvovirus minute virus of mice (MVMp) induces dramatic morphological alterations to the fibroblast host cell A9, resulting in cell lysis and progeny virus release. In order to understand the mechanisms underlying these changes, we characterized the fate of various cytoskeletal filaments and investigated the nuclear/cytoplasmic compartmentalization of infected cells. While most pronounced effects could be seen on micro- and intermediate filaments, manifest in dramatic rearrangements and degradation of filamentous (F-)actin and vimentin structures, only little impact could be seen on microtubules or the nuclear envelope during the entire monitored time of infection. To further analyze the disruption of the cytoskeletal structures, we investigated the viral impact on selective regulatory pathways. Thereby, we found a correlation between microtubule stability and MVM-induced phosphorylation of α/β tubulin. In contrast, disassembly of actin filaments late in infection could be traced back to the disregulation of two F-actin associated proteins gelsolin and Wiscott-Aldrich Syndrome Protein (WASP). Thereby, an increase in the amount of gelsolin, an F-actin severing protein was observed during infection, accounting for the disruption of stress fibers upon infection. Concomitantly, the actin polymerization activity also diminished due to a loss of WASP, the activator protein of the actin polymerization machinery the Arp2/3 complex. No effects could be seen in amount and distribution of other F-actin regulatory factors such as cortactin, cofilin, and profilin. In summary, the selective attack of MVM towards distinct host cell cytoskeletal structures argues for a regulatory feature during infection, rather than a collapse of the host cell as a mere side effect of virus production

Ehrlichia chaffeensis infection in the reservoir host (white-tailed deer and in an incidental host (dog is impacted by its prior growth in macrophage and tick cell environments.

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Arathy D S Nair

Full Text Available Ehrlichia chaffeensis, transmitted from Amblyomma americanum ticks, causes human monocytic ehrlichiosis. It also infects white-tailed deer, dogs and several other vertebrates. Deer are its reservoir hosts, while humans and dogs are incidental hosts. E. chaffeensis protein expression is influenced by its growth in macrophages and tick cells. We report here infection progression in deer or dogs infected intravenously with macrophage- or tick cell-grown E. chaffeensis or by tick transmission in deer. Deer and dogs developed mild fever and persistent rickettsemia; the infection was detected more frequently in the blood of infected animals with macrophage inoculum compared to tick cell inoculum or tick transmission. Tick cell inoculum and tick transmission caused a drop in tick infection acquisition rates compared to infection rates in ticks fed on deer receiving macrophage inoculum. Independent of deer or dogs, IgG antibody response was higher in animals receiving macrophage inoculum against macrophage-derived Ehrlichia antigens, while it was significantly lower in the same animals against tick cell-derived Ehrlichia antigens. Deer infected with tick cell inoculum and tick transmission caused a higher antibody response to tick cell cultured bacterial antigens compared to the antibody response for macrophage cultured antigens for the same animals. The data demonstrate that the host cell-specific E. chaffeensis protein expression influences rickettsemia in a host and its acquisition by ticks. The data also reveal that tick cell-derived inoculum is similar to tick transmission with reduced rickettsemia, IgG response and tick acquisition of E. chaffeensis.

Mycobacterium-Host Cell Relationships in Granulomatous Lesions in a Mouse Model of Latent Tuberculous Infection

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Elena Ufimtseva

2015-01-01

Full Text Available Tuberculosis (TB is a dangerous infectious disease characterized by a tight interplay between mycobacteria and host cells in granulomatous lesions (granulomas during the latent, asymptomatic stage of infection. Mycobacterium-host cell relationships were analyzed in granulomas obtained from various organs of BALB/c mice with chronic TB infection caused by in vivo exposure to the Bacillus Calmette-Guérin (BCG vaccine. Acid-fast BCG-mycobacteria were found to be morphologically and functionally heterogeneous (in size, shape, and replication rates in colonies in granuloma macrophages, dendritic cells, and multinucleate Langhans giant cells. Cord formation by BCG-mycobacteria in granuloma cells has been observed. Granuloma macrophages retained their ability to ingest damaged lymphocytes and thrombocytes in the phagosomes; however, their ability to destroy BCG-mycobacteria contained in these cells was compromised. No colocalization of BCG-mycobacteria and the LysoTracker dye was observed in the mouse cells. Various relationships between granuloma cells and BCG-mycobacteria were observed in different mice belonging to the same line. Several mice totally eliminated mycobacterial infection. Granulomas in the other mice had mycobacteria actively replicating in cells of different types and forming cords, which is an indicator of mycobacterial virulence and, probably, a marker of the activation of tuberculous infection in animals.

Mycobacterium-Host Cell Relationships in Granulomatous Lesions in a Mouse Model of Latent Tuberculous Infection

Science.gov (United States)

2015-01-01

Tuberculosis (TB) is a dangerous infectious disease characterized by a tight interplay between mycobacteria and host cells in granulomatous lesions (granulomas) during the latent, asymptomatic stage of infection. Mycobacterium-host cell relationships were analyzed in granulomas obtained from various organs of BALB/c mice with chronic TB infection caused by in vivo exposure to the Bacillus Calmette-Guérin (BCG) vaccine. Acid-fast BCG-mycobacteria were found to be morphologically and functionally heterogeneous (in size, shape, and replication rates in colonies) in granuloma macrophages, dendritic cells, and multinucleate Langhans giant cells. Cord formation by BCG-mycobacteria in granuloma cells has been observed. Granuloma macrophages retained their ability to ingest damaged lymphocytes and thrombocytes in the phagosomes; however, their ability to destroy BCG-mycobacteria contained in these cells was compromised. No colocalization of BCG-mycobacteria and the LysoTracker dye was observed in the mouse cells. Various relationships between granuloma cells and BCG-mycobacteria were observed in different mice belonging to the same line. Several mice totally eliminated mycobacterial infection. Granulomas in the other mice had mycobacteria actively replicating in cells of different types and forming cords, which is an indicator of mycobacterial virulence and, probably, a marker of the activation of tuberculous infection in animals. PMID:26064970

Recognizing the SINEs of Infection: Regulation of Retrotransposon Expression and Modulation of Host Cell Processes

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William Dunker

2017-12-01

Full Text Available Short interspersed elements (SINEs are a family of retrotransposons evolutionarily derived from cellular RNA polymerase III transcripts. Over evolutionary time, SINEs have expanded throughout the human genome and today comprise ~11% of total chromosomal DNA. While generally transcriptionally silent in healthy somatic cells, SINE expression increases during a variety of types of stresses, including DNA virus infection. The relevance of SINE expression to viral infection was largely unexplored, however, recent years have seen great progress towards defining the impact of SINE expression on viral replication and host gene expression. Here we review the origin and diversity of SINE elements and their transcriptional control, with an emphasis on how their expression impacts host cell biology during viral infection.

Coliphage 186 replication is delayed when the host cell is UV irradiated before infection

International Nuclear Information System (INIS)

Hooper, I.; Woods, W.H.; Egan, B.

1981-01-01

In contrast to results with injections by lambda and P2, the latent period for infection by coliphage 186 is extended when the host cell is UV irradiated before infection. We find that 186 replication is significantly delayed in such a cell, even though the phage itself has not been irradiated. In contrast, replication of the closely related phage P2 under the same conditions is not affected

Quantification of the host response proteome after mammalian reovirus T1L infection.

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Alicia R Berard

Full Text Available All viruses are dependent upon host cells for replication. Infection can induce profound changes within cells, including apoptosis, morphological changes, and activation of signaling pathways. Many of these alterations have been analyzed by gene arrays to measure the cellular "transcriptome." We used SILAC (stable isotope labeling by amino acids in cell culture, combined with high-throughput 2-D HPLC/mass spectrometry, to determine relative quantitative differences in host proteins at 6 and 24 hours after infecting HEK293 cells with reovirus serotype 1 Lang (T1L. 3,076 host proteins were detected at 6 hpi, of which 132 and 68 proteins were significantly up or down regulated, respectively. 2,992 cellular proteins, of which 104 and 49 were up or down regulated, respectively, were identified at 24 hpi. IPA and DAVID analyses indicated proteins involved in cell death, cell growth factors, oxygen transport, cell structure organization and inflammatory defense response to virus were up-regulated, whereas proteins involved in apoptosis, isomerase activity, and metabolism were down-regulated. These proteins and pathways may be suitable targets for intervention to either attenuate virus infection or enhance oncolytic potential.

Simultaneous transcriptional profiling of bacteria and their host cells.

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Michael S Humphrys

Full Text Available We developed an RNA-Seq-based method to simultaneously capture prokaryotic and eukaryotic expression profiles of cells infected with intracellular bacteria. As proof of principle, this method was applied to Chlamydia trachomatis-infected epithelial cell monolayers in vitro, successfully obtaining transcriptomes of both C. trachomatis and the host cells at 1 and 24 hours post-infection. Chlamydiae are obligate intracellular bacterial pathogens that cause a range of mammalian diseases. In humans chlamydiae are responsible for the most common sexually transmitted bacterial infections and trachoma (infectious blindness. Disease arises by adverse host inflammatory reactions that induce tissue damage & scarring. However, little is known about the mechanisms underlying these outcomes. Chlamydia are genetically intractable as replication outside of the host cell is not yet possible and there are no practical tools for routine genetic manipulation, making genome-scale approaches critical. The early timeframe of infection is poorly understood and the host transcriptional response to chlamydial infection is not well defined. Our simultaneous RNA-Seq method was applied to a simplified in vitro model of chlamydial infection. We discovered a possible chlamydial strategy for early iron acquisition, putative immune dampening effects of chlamydial infection on the host cell, and present a hypothesis for Chlamydia-induced fibrotic scarring through runaway positive feedback loops. In general, simultaneous RNA-Seq helps to reveal the complex interplay between invading bacterial pathogens and their host mammalian cells and is immediately applicable to any bacteria/host cell interaction.

Rodent Plasmodium-infected red blood cells: imaging their fates and interactions within their hosts.

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Claser, Carla; Malleret, Benoit; Peng, Kaitian; Bakocevic, Nadja; Gun, Sin Yee; Russell, Bruce; Ng, Lai Guan; Rénia, Laurent

2014-02-01

Malaria, a disease caused by the Plasmodium parasite, remains one of the most deadly infectious diseases known to mankind. The parasite has a complex life cycle, of which only the erythrocytic stage is responsible for the diverse pathologies induced during infection. To date, the disease mechanisms that underlie these pathologies are still poorly understood. In the case of infections caused by Plasmodium falciparum, the species responsible for most malaria related deaths, pathogenesis is thought to be due to the sequestration of infected red blood cells (IRBCs) in deep tissues. Other human and rodent malaria parasite species are also known to exhibit sequestration. Here, we review the different techniques that allow researchers to study how rodent malaria parasites modify their host cells, the distribution of IRBCs in vivo as well as the interactions between IRBCs and host tissues. © 2013. Published by Elsevier Ireland Ltd. All rights reserved.

RNA-Seq Based Transcriptome Analysis of the Type I Interferon Host Response upon Vaccinia Virus Infection of Mouse Cells

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Bruno Hernáez

2017-01-01

Full Text Available Vaccinia virus (VACV encodes the soluble type I interferon (IFN binding protein B18 that is secreted from infected cells and also attaches to the cell surface, as an immunomodulatory strategy to inhibit the host IFN response. By using next generation sequencing technologies, we performed a detailed RNA-seq study to dissect at the transcriptional level the modulation of the IFN based host response by VACV and B18. Transcriptome profiling of L929 cells after incubation with purified recombinant B18 protein showed that attachment of B18 to the cell surface does not trigger cell signalling leading to transcriptional activation. Consistent with its ability to bind type I IFN, B18 completely inhibited the IFN-mediated modulation of host gene expression. Addition of UV-inactivated virus particles to cell cultures altered the expression of a set of 53 cellular genes, including genes involved in innate immunity. Differential gene expression analyses of cells infected with replication competent VACV identified the activation of a broad range of host genes involved in multiple cellular pathways. Interestingly, we did not detect an IFN-mediated response among the transcriptional changes induced by VACV, even after the addition of IFN to cells infected with a mutant VACV lacking B18. This is consistent with additional viral mechanisms acting at different levels to block IFN responses during VACV infection.

Inhibition of host extracellular signal-regulated kinase (ERK) activation decreases new world alphavirus multiplication in infected cells

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Voss, Kelsey; Amaya, Moushimi [National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, 10650 Pyramid Place, Manassas, VA (United States); Mueller, Claudius [Center for Applied Proteomics and Personalized Medicine, George Mason University, 10900 University Boulevard, Manassas, VA (United States); Roberts, Brian [Leidos Health Life Sciences, 5202 Presidents Court, Suite 110, Frederick, MD (United States); Kehn-Hall, Kylene; Bailey, Charles [National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, 10650 Pyramid Place, Manassas, VA (United States); Petricoin, Emanuel [Center for Applied Proteomics and Personalized Medicine, George Mason University, 10900 University Boulevard, Manassas, VA (United States); Narayanan, Aarthi, E-mail: anaraya1@gmu.edu [National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, 10650 Pyramid Place, Manassas, VA (United States)

2014-11-15

New World alphaviruses belonging to the family Togaviridae are classified as emerging infectious agents and Category B select agents. Our study is focused on the role of the host extracellular signal-regulated kinase (ERK) in the infectious process of New World alphaviruses. Infection of human cells by Venezuelan equine encephalitis virus (VEEV) results in the activation of the ERK-signaling cascade. Inhibition of ERK1/2 by the small molecule inhibitor Ag-126 results in inhibition of viral multiplication. Ag-126-mediated inhibition of VEEV was due to potential effects on early and late stages of the infectious process. While expression of viral proteins was down-regulated in Ag-126 treated cells, we did not observe any influence of Ag-126 on the nuclear distribution of capsid. Finally, Ag-126 exerted a broad-spectrum inhibitory effect on New World alphavirus multiplication, thus indicating that the host kinase, ERK, is a broad-spectrum candidate for development of novel therapeutics against New World alphaviruses. - Highlights: • VEEV infection activated multiple components of the ERK signaling cascade. • Inhibition of ERK activation using Ag-126 inhibited VEEV multiplication. • Activation of ERK by Ceramide C6 increased infectious titers of TC-83. • Ag-126 inhibited virulent strains of all New World alphaviruses. • Ag-126 treatment increased percent survival of infected cells.

Inhibition of host extracellular signal-regulated kinase (ERK) activation decreases new world alphavirus multiplication in infected cells

International Nuclear Information System (INIS)

Voss, Kelsey; Amaya, Moushimi; Mueller, Claudius; Roberts, Brian; Kehn-Hall, Kylene; Bailey, Charles; Petricoin, Emanuel; Narayanan, Aarthi

2014-01-01

New World alphaviruses belonging to the family Togaviridae are classified as emerging infectious agents and Category B select agents. Our study is focused on the role of the host extracellular signal-regulated kinase (ERK) in the infectious process of New World alphaviruses. Infection of human cells by Venezuelan equine encephalitis virus (VEEV) results in the activation of the ERK-signaling cascade. Inhibition of ERK1/2 by the small molecule inhibitor Ag-126 results in inhibition of viral multiplication. Ag-126-mediated inhibition of VEEV was due to potential effects on early and late stages of the infectious process. While expression of viral proteins was down-regulated in Ag-126 treated cells, we did not observe any influence of Ag-126 on the nuclear distribution of capsid. Finally, Ag-126 exerted a broad-spectrum inhibitory effect on New World alphavirus multiplication, thus indicating that the host kinase, ERK, is a broad-spectrum candidate for development of novel therapeutics against New World alphaviruses. - Highlights: • VEEV infection activated multiple components of the ERK signaling cascade. • Inhibition of ERK activation using Ag-126 inhibited VEEV multiplication. • Activation of ERK by Ceramide C6 increased infectious titers of TC-83. • Ag-126 inhibited virulent strains of all New World alphaviruses. • Ag-126 treatment increased percent survival of infected cells

Bst1 is required for Candida albicans infecting host via facilitating cell wall anchorage of Glycosylphosphatidyl inositol anchored proteins

Science.gov (United States)

Liu, Wei; Zou, Zui; Huang, Xin; Shen, Hui; He, Li Juan; Chen, Si Min; Li, Li Ping; Yan, Lan; Zhang, Shi Qun; Zhang, Jun Dong; Xu, Zheng; Xu, Guo Tong; An, Mao Mao; Jiang, Yuan Ying

2016-01-01

Glycosylphosphatidyl inositol anchored proteins (GPI-APs) on fungal cell wall are essential for invasive infections. While the function of inositol deacylation of GPI-APs in mammalian cells has been previously characterized the impact of inositol deacylation in fungi and implications to host infection remains largely unexplored. Herein we describe our identification of BST1, an inositol deacylase of GPI-Aps in Candida albicans, was critical for GPI-APs cell wall attachment and host infection. BST1-deficient C. albicans (bst1Δ/Δ) was associated with severely impaired cell wall anchorage of GPI-APs and subsequen unmasked β-(1,3)-glucan. Consistent with the aberrant cell wall structures, bst1Δ/Δ strain did not display an invasive ability and could be recognized more efficiently by host immune systems. Moreover, BST1 null mutants or those expressing Bst1 variants did not display inositol deacylation activity and exhibited severely attenuated virulence and reduced organic colonization in a murine systemic candidiasis model. Thus, Bst1 can facilitate cell wall anchorage of GPI-APs in C. albicans by inositol deacylation, and is critical for host invasion and immune escape. PMID:27708385

SPOC1-mediated antiviral host cell response is antagonized early in human adenovirus type 5 infection

DEFF Research Database (Denmark)

Schreiner, Sabrina; Kinkley, Sarah; Bürck, Carolin

2013-01-01

, and playing a role in DNA damage response. SPOC1 co-localized with viral replication centers in the host cell nucleus, interacted with Ad DNA, and repressed viral gene expression at the transcriptional level. We discovered that this SPOC1-mediated restriction imposed upon Ad growth is relieved by its...... viruses (HSV-1, HSV-2, HIV-1, and HCV) also depleted SPOC1 in infected cells. Our findings provide a general model for how pathogenic human viruses antagonize intrinsic SPOC1-mediated antiviral responses in their host cells. A better understanding of viral entry and early restrictive functions in host...

Within-host spatiotemporal dynamics of plant virus infection at the cellular level.

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Nicolas Tromas

2014-02-01

Full Text Available A multicellular organism is not a monolayer of cells in a flask; it is a complex, spatially structured environment, offering both challenges and opportunities for viruses to thrive. Whereas virus infection dynamics at the host and within-cell levels have been documented, the intermediate between-cell level remains poorly understood. Here, we used flow cytometry to measure the infection status of thousands of individual cells in virus-infected plants. This approach allowed us to determine accurately the number of cells infected by two virus variants in the same host, over space and time as the virus colonizes the host. We found a low overall frequency of cellular infection (<0.3, and few cells were coinfected by both virus variants (<0.1. We then estimated the cellular contagion rate (R, the number of secondary infections per infected cell per day. R ranged from 2.43 to values not significantly different from zero, and generally decreased over time. Estimates of the cellular multiplicity of infection (MOI, the number of virions infecting a cell, were low (<1.5. Variance of virus-genotype frequencies increased strongly from leaf to cell levels, in agreement with a low MOI. Finally, there were leaf-dependent differences in the ease with which a leaf could be colonized, and the number of virions effectively colonizing a leaf. The modeling of infection patterns suggests that the aggregation of virus-infected cells plays a key role in limiting spread; matching the observation that cell-to-cell movement of plant viruses can result in patches of infection. Our results show that virus expansion at the between-cell level is restricted, probably due to the host environment and virus infection itself.

Bartonella entry mechanisms into mammalian host cells.

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Eicher, Simone C; Dehio, Christoph

2012-08-01

The Gram-negative genus Bartonella comprises arthropod-borne pathogens that typically infect mammals in a host-specific manner. Bartonella bacilliformis and Bartonella quintana are human-specific pathogens, while several zoonotic bartonellae specific for diverse animal hosts infect humans as an incidental host. Clinical manifestations of Bartonella infections range from mild symptoms to life-threatening disease. Following transmission by blood-sucking arthropods or traumatic contact with infected animals, bartonellae display sequential tropisms towards endothelial and possibly other nucleated cells and erythrocytes, the latter in a host-specific manner. Attachment to the extracellular matrix (ECM) and to nucleated cells is mediated by surface-exposed bacterial adhesins, in particular trimeric autotransporter adhesins (TAAs). The subsequent engulfment of the pathogen into a vacuolar structure follows a unique series of events whereby the pathogen avoids the endolysosomal compartments. For Bartonella henselae and assumingly most other species, the infection process is aided at different steps by Bartonella effector proteins (Beps). They are injected into host cells through the type IV secretion system (T4SS) VirB/D4 and subvert host cellular functions to favour pathogen uptake. Bacterial binding to erythrocytes is mediated by Trw, another T4SS, in a strictly host-specific manner, followed by pathogen-forced uptake involving the IalB invasin and subsequent replication and persistence within a membrane-bound intra-erythrocytic compartment. © 2012 Blackwell Publishing Ltd.

The Influence of Virus Infection on the Extracellular pH of the Host Cell Detected on Cell Membrane.

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Liu, Hengjun; Maruyama, Hisataka; Masuda, Taisuke; Honda, Ayae; Arai, Fumihito

2016-01-01

Influenza virus infection can result in changes in the cellular ion levels at 2-3 h post-infection. More H(+) is produced by glycolysis, and the viral M2 proton channel also plays a role in the capture and release of H(+) during both viral entry and egress. Then the cells might regulate the intracellular pH by increasing the export of H(+) from the intracellular compartment. Increased H(+) export could lead indirectly to increased extracellular acidity. To detect changes in extracellular pH of both virus-infected and uninfected cells, pH sensors were synthesized using polystyrene beads (ϕ1 μm) containing Rhodamine B and Fluorescein isothiocyanate (FITC). The fluorescence intensity of FITC can respond to both pH and temperature. So Rhodamine B was also introduced in the sensor for temperature compensation. Then the pH can be measured after temperature compensation. The sensor was adhered to cell membrane for extracellular pH measurement. The results showed that the multiplication of influenza virus in host cell decreased extracellular pH of the host cell by 0.5-0.6 in 4 h after the virus bound to the cell membrane, compared to that in uninfected cells. Immunostaining revealed the presence of viral PB1 protein in the nucleus of virus-bound cells that exhibited extracellular pH changes, but no PB1 protein are detected in virus-unbound cells where the extracellular pH remained constant.

The influence of virus infection on the extracellular pH of the host cell detected on cell membrane

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Hengjun Liu

2016-08-01

Full Text Available Influenza virus infection can result in changes in the cellular ion levels at 2–3 hours post-infection. More H+ is produced by glycolysis, and the viral M2 proton channel also plays a role in the capture and release of H+ during both viral entry and egress. Then the cells might regulate the intracellular pH by increasing the export of H+ from the intracellular compartment. Increased H+ export could lead indirectly to increased extracellular acidity. To detect changes in extracellular pH of both virus-infected and uninfected cells, pH sensors were synthesized using polystyrene beads (1μm containing Rhodamine B and Fluorescein isothiocyanate (FITC. The fluorescence intensity of FITC can respond to both pH and temperature. So Rhodamine B was also introduced in the sensor for temperature compensation. Then the pH can be measured after temperature compensation. The sensor was adhered to cell membrane for extracellular pH measurement. The results showed that the multiplication of influenza virus in host cell decreased extracellular pH of the host cell by 0.5–0.6 in 4 hours after the virus bound to the cell membrane, compared to that in uninfected cells. Immunostaining revealed the presence of viral PB1 subunits in the nucleus of virus-bound cells that exhibited extracellular pH changes, but no PB1 subunits are detected in virus-unbound cells where the extracellular pH remained constant.

Salmonella modulation of host cell gene expression promotes its intracellular growth.

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Sebastian Hannemann

Full Text Available Salmonella Typhimurium has evolved a complex functional interface with its host cell largely determined by two type III secretion systems (T3SS, which through the delivery of bacterial effector proteins modulate a variety of cellular processes. We show here that Salmonella Typhimurium infection of epithelial cells results in a profound transcriptional reprogramming that changes over time. This response is triggered by Salmonella T3SS effector proteins, which stimulate unique signal transduction pathways leading to STAT3 activation. We found that the Salmonella-stimulated changes in host cell gene expression are required for the formation of its specialized vesicular compartment that is permissive for its intracellular replication. This study uncovers a cell-autonomous process required for Salmonella pathogenesis potentially opening up new avenues for the development of anti-infective strategies that target relevant host pathways.

Salmonella modulation of host cell gene expression promotes its intracellular growth.

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Hannemann, Sebastian; Gao, Beile; Galán, Jorge E

2013-01-01

Salmonella Typhimurium has evolved a complex functional interface with its host cell largely determined by two type III secretion systems (T3SS), which through the delivery of bacterial effector proteins modulate a variety of cellular processes. We show here that Salmonella Typhimurium infection of epithelial cells results in a profound transcriptional reprogramming that changes over time. This response is triggered by Salmonella T3SS effector proteins, which stimulate unique signal transduction pathways leading to STAT3 activation. We found that the Salmonella-stimulated changes in host cell gene expression are required for the formation of its specialized vesicular compartment that is permissive for its intracellular replication. This study uncovers a cell-autonomous process required for Salmonella pathogenesis potentially opening up new avenues for the development of anti-infective strategies that target relevant host pathways.

Genome-wide transcriptional profiling of Botrytis cinerea genes targeting plant cell walls during infections of different hosts

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Barbara eBlanco-Ulate

2014-09-01

Full Text Available Cell walls are barriers that impair colonization of host tissues, but also are important reservoirs of energy-rich sugars. Growing hyphae of necrotrophic fungal pathogens, such as Botrytis cinerea (Botrytis, henceforth, secrete enzymes that disassemble cell wall polysaccharides. In this work we describe the annotation of 275 putative secreted Carbohydrate-Active enZymes (CAZymes identified in the Botrytis B05.10 genome. Using RNAseq we determined which Botrytis CAZymes were expressed during infections of lettuce leaves, ripe tomato fruit, and grape berries. On the three hosts, Botrytis expressed a common group of 229 potentially secreted CAZymes, including 28 pectin backbone-modifying enzymes, 21 hemicellulose-modifying proteins, 18 enzymes that might target pectin and hemicellulose side-branches, and 16 enzymes predicted to degrade cellulose. The diversity of the Botrytis CAZymes may be partly responsible for its wide host range. Thirty-six candidate CAZymes with secretion signals were found exclusively when Botrytis interacted with ripe tomato fruit and grape berries. Pectin polysaccharides are notably abundant in grape and tomato cell walls, but lettuce leaf walls have less pectin and are richer in hemicelluloses and cellulose. The results of this study not only suggest that Botrytis targets similar wall polysaccharide networks on fruit and leaves, but also that it may selectively attack host wall polysaccharide substrates depending on the host tissue.

Host cell reactivation and UV-enhanced reactivation in synchronized mammalian cells

International Nuclear Information System (INIS)

Lytle, C.D.; Schmidt, B.J.

1981-01-01

Does host cell reactivation (HCR) or UV-enhanced reactivation (UVER) of UV-irradiated Herpes simplex virus (UV-HSV) vary during the host mammalian cell cycle. The answer could be useful for interpreting UVER and or the two-component nature of the UV-HSV survival curve. Procedures were developed for infection of mitotically-synchronized CV-l monkey kidney cells. All virus survival curves determined at different cell cycle stages had two components with similar D 0 's and intercepts of the second components. Thus, no single stage of the host cell cycle was responsible for the second component of the virus survival curve. When the cells were UV-irradiated immediately prior to infection, enhanced survival of UV-HSV occurred for cell irradiation and virus infection initiated during late G 1 early S phase or late S early G 2 phase but not during early G 1 phase. For infection delayed by 24 h after cell irradiation, UVER was found at all investigated times. These results indicate that: (1) HCR is similar at all stages of the host cell cycle: and (2) the ''induction'' of UVER is not as rapid for cell-irradiation in early G 1 phase. This latter observation may be one reason why normal, contact-inhibited cells do not express UVER as rapidly as faster growing, less contact-inhibited cells. (author)

Differences between Mycobacterium-Host Cell Relationships in Latent Tuberculous Infection of Mice Ex Vivo and Mycobacterial Infection of Mouse Cells In Vitro

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Elena Ufimtseva

2016-01-01

Full Text Available The search for factors that account for the reproduction and survival of mycobacteria, including vaccine strains, in host cells is the priority for studies on tuberculosis. A comparison of BCG-mycobacterial loads in granuloma cells obtained from bone marrow and spleens of mice with latent tuberculous infection and cells from mouse bone marrow and peritoneal macrophage cultures infected with the BCG vaccine in vitro has demonstrated that granuloma macrophages each normally contained a single BCG-Mycobacterium, while those acutely infected in vitro had increased mycobacterial loads and death rates. Mouse granuloma cells were observed to produce the IFNγ, IL-1α, GM-CSF, CD1d, CD25, CD31, СD35, and S100 proteins. None of these activation markers were found in mouse cell cultures infected in vitro or in intact macrophages. Lack of colocalization of lipoarabinomannan-labeled BCG-mycobacteria with the lysosomotropic LysoTracker dye in activated granuloma macrophages suggests that these macrophages were unable to destroy BCG-mycobacteria. However, activated mouse granuloma macrophages could control mycobacterial reproduction in cells both in vivo and in ex vivo culture. By contrast, a considerable increase in the number of BCG-mycobacteria was observed in mouse bone marrow and peritoneal macrophages after BCG infection in vitro, when no expression of the activation-related molecules was detected in these cells.

Absolute Quantification of the Host-To-Parasite DNA Ratio in Theileria parva-Infected Lymphocyte Cell Lines.

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Gotia, Hanzel T; Munro, James B; Knowles, Donald P; Daubenberger, Claudia A; Bishop, Richard P; Silva, Joana C

2016-01-01

Theileria parva is a tick-transmitted intracellular apicomplexan pathogen of cattle in sub-Saharan Africa that causes East Coast fever (ECF). ECF is an acute fatal disease that kills over one million cattle annually, imposing a tremendous burden on African small-holder cattle farmers. The pathology and level of T. parva infections in its wildlife host, African buffalo (Syncerus caffer), and in cattle are distinct. We have developed an absolute quantification method based on quantitative PCR (qPCR) in which recombinant plasmids containing single copy genes specific to the parasite (apical membrane antigen 1 gene, ama1) or the host (hypoxanthine phosphoribosyltransferase 1, hprt1) are used as the quantification reference standards. Our study shows that T. parva and bovine cells are present in similar numbers in T. parva-infected lymphocyte cell lines and that consequently, due to its much smaller genome size, T. parva DNA comprises between 0.9% and 3% of the total DNA samples extracted from these lines. This absolute quantification assay of parasite and host genome copy number in a sample provides a simple and reliable method of assessing T. parva load in infected bovine lymphocytes, and is accurate over a wide range of host-to-parasite DNA ratios. Knowledge of the proportion of target DNA in a sample, as enabled by this method, is essential for efficient high-throughput genome sequencing applications for a variety of intracellular pathogens. This assay will also be very useful in future studies of interactions of distinct host-T. parva stocks and to fully characterize the dynamics of ECF infection in the field.

Host response to Brucella infection: review and future perspective.

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Elfaki, Mohamed G; Alaidan, Alwaleed Abdullah; Al-Hokail, Abdullah Abdulrahman

2015-07-30

Brucellosis is a zoonotic and contagious infectious disease caused by infection with Brucella species. The infecting brucellae are capable of causing a devastating multi-organ disease in humans with serious health complications. The pathogenesis of Brucella infection is influenced largely by host factors, Brucella species/strain, and the ability of invading brucellae to survive and replicate within mononuclear phagocytic cells, preferentially macrophages (Mf). Consequently, the course of human infection may appear as an acute fatal or progress into chronic debilitating infection with periodical episodes that leads to bacteremia and death. The existence of brucellae inside Mf represents one of the strategies used by Brucella to evade the host immune response and is responsible for treatment failure in certain human populations treated with anti-Brucella drugs. Moreover, the persistence of brucellae inside Mf complicates the diagnosis and may affect the host cell signaling pathways with consequent alterations in both innate and adaptive immune responses. Therefore, there is an urgent need to pursue the development of novel drugs and/or vaccine targets against human brucellosis using high throughput technologies in genomics, proteomics, and immunology.

Ebola virus host cell entry.

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Sakurai, Yasuteru

2015-01-01

Ebola virus is an enveloped virus with filamentous structure and causes a severe hemorrhagic fever in human and nonhuman primates. Host cell entry is the first essential step in the viral life cycle, which has been extensively studied as one of the therapeutic targets. A virus factor of cell entry is a surface glycoprotein (GP), which is an only essential viral protein in the step, as well as the unique particle structure. The virus also interacts with a lot of host factors to successfully enter host cells. Ebola virus at first binds to cell surface proteins and internalizes into cells, followed by trafficking through endosomal vesicles to intracellular acidic compartments. There, host proteases process GPs, which can interact with an intracellular receptor. Then, under an appropriate circumstance, viral and endosomal membranes are fused, which is enhanced by major structural changes of GPs, to complete host cell entry. Recently the basic research of Ebola virus infection mechanism has markedly progressed, largely contributed by identification of host factors and detailed structural analyses of GPs. This article highlights the mechanism of Ebola virus host cell entry, including recent findings.

Small RNA Profiling in Dengue Virus 2-Infected Aedes Mosquito Cells Reveals Viral piRNAs and Novel Host miRNAs.

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Miesen, Pascal; Ivens, Alasdair; Buck, Amy H; van Rij, Ronald P

2016-02-01

In Aedes mosquitoes, infections with arthropod-borne viruses (arboviruses) trigger or modulate the expression of various classes of viral and host-derived small RNAs, including small interfering RNAs (siRNAs), PIWI interacting RNAs (piRNAs), and microRNAs (miRNAs). Viral siRNAs are at the core of the antiviral RNA interference machinery, one of the key pathways that limit virus replication in invertebrates. Besides siRNAs, Aedes mosquitoes and cells derived from these insects produce arbovirus-derived piRNAs, the best studied examples being viruses from the Togaviridae or Bunyaviridae families. Host miRNAs modulate the expression of a large number of genes and their levels may change in response to viral infections. In addition, some viruses, mostly with a DNA genome, express their own miRNAs to regulate host and viral gene expression. Here, we perform a comprehensive analysis of both viral and host-derived small RNAs in Aedes aegypti Aag2 cells infected with dengue virus 2 (DENV), a member of the Flaviviridae family. Aag2 cells are competent in producing all three types of small RNAs and provide a powerful tool to explore the crosstalk between arboviral infection and the distinct RNA silencing pathways. Interestingly, besides the well-characterized DENV-derived siRNAs, a specific population of viral piRNAs was identified in infected Aag2 cells. Knockdown of Piwi5, Ago3 and, to a lesser extent, Piwi6 results in reduction of vpiRNA levels, providing the first genetic evidence that Aedes PIWI proteins produce DENV-derived small RNAs. In contrast, we do not find convincing evidence for the production of virus-derived miRNAs. Neither do we find that host miRNA expression is strongly changed upon DENV2 infection. Finally, our deep-sequencing analyses detect 30 novel Aedes miRNAs, complementing the repertoire of regulatory small RNAs in this important vector species.

Metabolic investigation of host/pathogen interaction using MS2-infected Escherichia coli

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Jain Rishi

2009-12-01

Full Text Available Abstract Background RNA viruses are responsible for a variety of illnesses among people, including but not limited to the common cold, the flu, HIV, and ebola. Developing new drugs and new strategies for treating diseases caused by these viruses can be an expensive and time-consuming process. Mathematical modeling may be used to elucidate host-pathogen interactions and highlight potential targets for drug development, as well providing the basis for optimizing patient treatment strategies. The purpose of this work was to determine whether a genome-scale modeling approach could be used to understand how metabolism is impacted by the host-pathogen interaction during a viral infection. Escherichia coli/MS2 was used as the host-pathogen model system as MS2 is easy to work with, harmless to humans, but shares many features with eukaryotic viruses. In addition, the genome-scale metabolic model of E. coli is the most comprehensive model at this time. Results Employing a metabolic modeling strategy known as "flux balance analysis" coupled with experimental studies, we were able to predict how viral infection would alter bacterial metabolism. Based on our simulations, we predicted that cell growth and biosynthesis of the cell wall would be halted. Furthermore, we predicted a substantial increase in metabolic activity of the pentose phosphate pathway as a means to enhance viral biosynthesis, while a break down in the citric acid cycle was predicted. Also, no changes were predicted in the glycolytic pathway. Conclusions Through our approach, we have developed a technique of modeling virus-infected host metabolism and have investigated the metabolic effects of viral infection. These studies may provide insight into how to design better drugs. They also illustrate the potential of extending such metabolic analysis to higher order organisms, including humans.

Toxoplasma gondii infection specifically increases the levels of key host microRNAs.

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Gusti M Zeiner

2010-01-01

Full Text Available The apicomplexan parasite Toxoplasma gondii can infect and replicate in virtually any nucleated cell in many species of warm-blooded animals; thus, it has evolved the ability to exploit well-conserved biological processes common to its diverse hosts. Here we have investigated whether Toxoplasma modulates the levels of host microRNAs (miRNAs during infection.Using microarray profiling and a combination of conventional molecular approaches we report that Toxoplasma specifically modulates the expression of important host microRNAs during infection. We show that both the primary transcripts for miR-17 approximately 92 and miR-106b approximately 25 and the pivotal miRNAs that are derived from miR-17 approximately 92 display increased abundance in Toxoplasma-infected primary human cells; a Toxoplasma-dependent up-regulation of the miR-17 approximately 92 promoter is at least partly responsible for this increase. The abundance of mature miR-17 family members, which are derived from these two miRNA clusters, remains unchanged in host cells infected with the closely related apicomplexan Neospora caninum; thus, the Toxoplasma-induced increase in their abundance is a highly directed process rather than a general host response to infection.Altered levels of miR-17 approximately 92 and miR-106b approximately 25 are known to play crucial roles in mammalian cell regulation and have been implicated in numerous hyperproliferative diseases although the mechanisms driving their altered expression are unknown. Hence, in addition to the implications of these findings on the host-pathogen interaction, Toxoplasma may represent a powerful probe for understanding the normal mechanisms that regulate the levels of key host miRNAs.

Transcriptome and microRNome of Theileria annulata Host Cells

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Rchiad, Zineb

2016-06-01

Tropical Theileriosis is a parasitic disease of calves with a profound economic impact caused by Theileria annulata, an apicomplexan parasite of the genus Theileria. Transmitted by Hyalomma ticks, T. annulata infects and transforms bovine lymphocytes and macrophages into a cancer-like phenotype characterized by all six hallmarks of cancer. In the current study we investigate the transcriptional landscape of T. annulata-infected lymphocytes to define genes and miRNAs regulated by host cell transformation using next generation sequencing. We also define genes and miRNAs differentially expressed as a result of the attenuation of a T.annulata-infected macrophage cell line used as a vaccine. By comparing the transcriptional landscape of one attenuated and two transformed cell lines we identify four genes that we propose as key factors in transformation and virulence of the T. annulata host cells. We also identify miR- 126-5p as a key regulator of infected cells proliferation, adhesion, survival and invasiveness. In addition to the host cell trascriptome we studied T. annulata transcriptome and identified the role of ROS and TGF-β2 in controlling parasite gene expression. Moreover, we have used the deep parasite ssRNA-seq data to refine the available T. annulata annotation. Taken together, this study provides the full list of host cell’s genes and miRNAs transcriptionally perturbed after infection with T. annulata and after attenuation and describes genes and miRNAs never identified before as players in this type of host cell transformation. Moreover, this study provides the first database for the transcriptome of T. annulata and its host cells using next generation sequencing.

Quantitative proteomic analysis of HIV-1 infected CD4+ T cells reveals an early host response in important biological pathways: Protein synthesis, cell proliferation, and T-cell activation

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Navare, Arti T.; Sova, Pavel; Purdy, David E.; Weiss, Jeffrey M. [Department of Microbiology, University of Washington, Seattle, WA (United States); Wolf-Yadlin, Alejandro [Department of Genome Sciences, University of Washington, Seattle, WA (United States); Korth, Marcus J.; Chang, Stewart T.; Proll, Sean C. [Department of Microbiology, University of Washington, Seattle, WA (United States); Jahan, Tahmina A. [Proteomics Resource, UW Medicine at South Lake Union, Seattle, WA (United States); Krasnoselsky, Alexei L.; Palermo, Robert E. [Department of Microbiology, University of Washington, Seattle, WA (United States); Katze, Michael G., E-mail: honey@uw.edu [Department of Microbiology, University of Washington, Seattle, WA (United States); Washington National Primate Research Center, University of Washington, Seattle, WA (United States)

2012-07-20

Human immunodeficiency virus (HIV-1) depends upon host-encoded proteins to facilitate its replication while at the same time inhibiting critical components of innate and/or intrinsic immune response pathways. To characterize the host cell response on protein levels in CD4+ lymphoblastoid SUP-T1 cells after infection with HIV-1 strain LAI, we used mass spectrometry (MS)-based global quantitation with iTRAQ (isobaric tag for relative and absolute quantification). We found 266, 60 and 22 proteins differentially expressed (DE) (P-value{<=}0.05) at 4, 8, and 20 hours post-infection (hpi), respectively, compared to time-matched mock-infected samples. The majority of changes in protein abundance occurred at an early stage of infection well before the de novo production of viral proteins. Functional analyses of these DE proteins showed enrichment in several biological pathways including protein synthesis, cell proliferation, and T-cell activation. Importantly, these early changes before the time of robust viral production have not been described before.

Host density and competency determine the effects of host diversity on trematode parasite infection.

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Jeremy M Wojdak

Full Text Available Variation in host species composition can dramatically alter parasite transmission in natural communities. Whether diverse host communities dilute or amplify parasite transmission is thought to depend critically on species traits, particularly on how hosts affect each other's densities, and their relative competency as hosts. Here we studied a community of potential hosts and/or decoys (i.e. non-competent hosts for two trematode parasite species, Echinostoma trivolvis and Ribeiroia ondatrae, which commonly infect wildlife across North America. We manipulated the density of a focal host (green frog tadpoles, Rana clamitans, in concert with manipulating the diversity of alternative species, to simulate communities where alternative species either (1 replace the focal host species so that the total number of individuals remains constant (substitution or (2 add to total host density (addition. For E. trivolvis, we found that total parasite transmission remained roughly equal (or perhaps decreased slightly when alternative species replaced focal host individuals, but parasite transmission was higher when alternative species were added to a community without replacing focal host individuals. Given the alternative species were roughly equal in competency, these results are consistent with current theory. Remarkably, both total tadpole and per-capita tadpole infection intensity by E. trivolvis increased with increasing intraspecific host density. For R. ondatrae, alternative species did not function as effective decoys or hosts for parasite infective stages, and the diversity and density treatments did not produce clear changes in parasite transmission, although high tank to tank variation in R. ondatrae infection could have obscured patterns.

Trans-suppression of host CDH3 and LOXL4 genes during Cryptosporidium parvum infection involves nuclear delivery of parasite Cdg7_FLc_1000 RNA.

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Ming, Zhenping; Gong, Ai-Yu; Wang, Yang; Zhang, Xin-Tian; Li, Min; Li, Yao; Pang, Jing; Dong, Stephanie; Strauss-Soukup, Juliane K; Chen, Xian-Ming

2018-05-01

Intestinal infection by Cryptosporidium parvum causes significant alterations in the gene expression profile in host epithelial cells. Previous studies demonstrate that a panel of parasite RNA transcripts of low protein-coding potential are delivered into infected host cells and may modulate host gene transcription. Using in vitro models of human intestinal cryptosporidiosis, we report here that trans-suppression of the cadherin 3 (CDH3) and lysyl oxidase like 4 (LOXL4) genes in human intestinal epithelial cells following C. parvum infection involves host delivery of the Cdg7_FLc_1000 RNA, a C. parvum RNA that has been previously demonstrated to be delivered into the nuclei of infected host cells. Downregulation of CDH3 and LOXL4 genes was detected in host epithelial cells following C. parvum infection or in cells expressing the parasite Cdg7_FLc_1000 RNA. Knockdown of Cdg7_FLc_1000 attenuated the trans-suppression of CDH3 and LOXL4 genes in host cells induced by infection. Interestingly, Cdg7_FLc_1000 was detected to be recruited to the promoter regions of both CDH3 and LOXL4 gene loci in host cells following C. parvum infection. Host delivery of Cdg7_FLc_1000 promoted the PH domain zinc finger protein 1 (PRDM1)-mediated H3K9 methylation associated with trans-suppression in the CDH3 gene locus, but not the LOXL4 gene. Therefore, our data suggest that host delivery of Cdg7_FLc_1000 causes CDH3 trans-suppression in human intestinal epithelial cells following C. parvum infection through PRDM1-mediated H3K9 methylation in the CDH3 gene locus, whereas Cdg7_FLc_1000 induces trans-suppression of the host LOXL4 gene through H3K9/H3K27 methylation-independent mechanisms. Copyright © 2018 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

Differences in infectivity between endosymbiotic Chlorella variabilis cultivated outside host Paramecium bursaria for 50 years and those immediately isolated from host cells after one year of reendosymbiosis

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Y. Kodama

2016-01-01

Full Text Available Chlorella variabilis strain NC64A is an intracellular photobiont of the ciliate Paramecium bursaria. NC64A was isolated from P. bursaria nearly 50 years ago and was thereafter cultivated outside the host. This study was undertaken to detect changes in its infectivity to P. bursaria and its auxotrophy for growth outside the host induced during long-term cultivation. NC64A can grow in Modified Bold's Basal Medium but not in C medium, whereas another symbiotic Chlorella variabilis strain, 1N, that was recently isolated from the host grew in C medium but not in Modified Bold's Basal Medium. With regards infectivity, NC64A in the logarithmic phase of growth showed low infectivity to alga-removed P. bursaria cells, whereas those in the early stationary phase showed high infectivity of about 30%. Those in the decay phase of growth showed no infectivity. Results show that NC64A has infectivity, but the infection rate depends on their culture age in the growth curve. Furthermore, NC64A that had been re-infected to P. bursaria for more than one year and isolated from the host showed a nearly 100% infection rate, which indicates that NC64A can recover its infectivity by re-infection to P. bursaria.

Host Factors in Ebola Infection.

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Rasmussen, Angela L

2016-08-31

Ebola virus (EBOV) emerged in West Africa in 2014 to devastating effect, and demonstrated that infection can cause a broad range of severe disease manifestations. As the virus itself was genetically similar to other Zaire ebolaviruses, the spectrum of pathology likely resulted from variable responses to infection in a large and genetically diverse population. This review comprehensively summarizes current knowledge of the host response to EBOV infection, including pathways hijacked by the virus to facilitate replication, host processes that contribute directly to pathogenesis, and host-pathogen interactions involved in subverting or antagonizing host antiviral immunity.

Inhibition of host cell protein synthesis by UV-inactivated poliovirus

International Nuclear Information System (INIS)

Helentjaris, T.; Ehrenfeld, E.

1977-01-01

The ability of poliovirus that was irradiated with UV light at energies up to 2,160 ergs/mm 2 to subsequently inhibit host cell protein synthesis was measured. The inactivation of the host cell shutoff function followed one-hit kinetics. Increasing irradiation did not affect the rate of inhibition until the multiplicity of infection after irradiation was reduced to approximately 1 PFU/cell. At higher functional multiplicities, the rate was unchanged, but an increasing lag before the onset of inhibition was observed with increasing irradiation. The energy levels required to inactivate virus-induced inhibition of host cell protein synthesis suggest that damage to virus RNA rather than to virus capsid proteins is responsible for the loss of function. When the inactivation of host cell shutoff was compared with the inactivation of other viral functions by UV irradiation, it correlated exactly with the loss of infectivity but not with other viral functions measured. Guanidine treatment, which prevents detectable viral RNA and protein synthesis, completely inhibited host cell shutoff by low multiplicities of unirradiated virus infection but not higher multiplicities. When a high multiplicity of virus was first reduced to a low titer by irradiation, host cell shutoff was still evident in the presence of guanidine. The results demonstrate that the complete inhibition of host cell protein synthesis can be accomplished by one infectious viral genome per cell

Merkel cell polyomavirus infection and Merkel cell carcinoma.

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Liu, Wei; MacDonald, Margo; You, Jianxin

2016-10-01

Merkel cell polyomavirus is the only polyomavirus discovered to date that is associated with a human cancer. MCPyV infection is highly prevalent in the general population. Nearly all healthy adults asymptomatically shed MCPyV from their skin. However, in elderly and immunosuppressed individuals, the infection can lead to a lethal form of skin cancer, Merkel cell carcinoma. In the last few years, new findings have established links between MCPyV infection, host immune response, and Merkel cell carcinoma development. This review discusses these recent discoveries on how MCPyV interacts with host cells to achieve persistent infection and, in the immunocompromised population, contributes to MCC development. Copyright © 2016 Elsevier B.V. All rights reserved.

Trichomonas vaginalis and Tritrichomonas foetus: interaction with fibroblasts and muscle cells - new insights into parasite-mediated host cell cytotoxicity

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Ricardo Chaves Vilela

2012-09-01

Full Text Available Trichomonas vaginalis and Tritrichomonas foetus are parasitic, flagellated protists that inhabit the urogenital tract of humans and bovines, respectively. T. vaginalis causes the most prevalent non-viral sexually transmitted disease worldwide and has been associated with an increased risk for human immunodeficiency virus-1 infection in humans. Infections by T. foetus cause significant losses to the beef industry worldwide due to infertility and spontaneous abortion in cows. Several studies have shown a close association between trichomonads and the epithelium of the urogenital tract. However, little is known concerning the interaction of trichomonads with cells from deeper tissues, such as fibroblasts and muscle cells. Published parasite-host cell interaction studies have reported contradictory results regarding the ability of T. foetus and T. vaginalis to interact with and damage cells of different tissues. In this study, parasite-host cell interactions were examined by culturing primary human fibroblasts obtained from abdominal biopsies performed during plastic surgeries with trichomonads. In addition, mouse 3T3 fibroblasts, primary chick embryo myogenic cells and L6 muscle cells were also used as models of target cells. The parasite-host cell cultures were processed for scanning and transmission electron microscopy and were tested for cell viability and cell death. JC-1 staining, which measures mitochondrial membrane potential, was used to determine whether the parasites induced target cell damage. Terminal deoxynucleotidyltransferase-mediated dUTP nick end labelling staining was used as an indicator of chromatin damage. The colorimetric crystal violet assay was performed to ana-lyse the cytotoxicity induced by the parasite. The results showed that T. foetus and T. vaginalis adhered to and were cytotoxic to both fibroblasts and muscle cells, indicating that trichomonas infection of the connective and muscle tissues is likely to occur; such

N-Terminomics TAILS Identifies Host Cell Substrates of Poliovirus and Coxsackievirus B3 3C Proteinases That Modulate Virus Infection

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Jagdeo, Julienne M.; Dufour, Antoine; Klein, Theo; Solis, Nestor; Kleifeld, Oded; Kizhakkedathu, Jayachandran; Luo, Honglin; Overall, Christopher M.

2018-01-01

ABSTRACT Enteroviruses encode proteinases that are essential for processing of the translated viral polyprotein. In addition, viral proteinases also target host proteins to manipulate cellular processes and evade innate antiviral responses to promote replication and infection. Although some host protein substrates of enterovirus proteinases have been identified, the full repertoire of targets remains unknown. We used a novel quantitative in vitro proteomics-based approach, termed terminal amine isotopic labeling of substrates (TAILS), to identify with high confidence 72 and 34 new host protein targets of poliovirus and coxsackievirus B3 (CVB3) 3C proteinases (3Cpros) in HeLa cell and cardiomyocyte HL-1 cell lysates, respectively. We validated a subset of candidate substrates that are targets of poliovirus 3Cpro in vitro including three common protein targets, phosphoribosylformylglycinamidine synthetase (PFAS), hnRNP K, and hnRNP M, of both proteinases. 3Cpro-targeted substrates were also cleaved in virus-infected cells but not noncleavable mutant proteins designed from the TAILS-identified cleavage sites. Knockdown of TAILS-identified target proteins modulated infection both negatively and positively, suggesting that cleavage by 3Cpro promotes infection. Indeed, expression of a cleavage-resistant mutant form of the endoplasmic reticulum (ER)-Golgi vesicle-tethering protein p115 decreased viral replication and yield. As the first comprehensive study to identify and validate functional enterovirus 3Cpro substrates in vivo, we conclude that N-terminomics by TAILS is an effective strategy to identify host targets of viral proteinases in a nonbiased manner. IMPORTANCE Enteroviruses are positive-strand RNA viruses that encode proteases that cleave the viral polyprotein into the individual mature viral proteins. In addition, viral proteases target host proteins in order to modulate cellular pathways and block antiviral responses in order to facilitate virus infection

Identification of RNA Binding Proteins Associated with Dengue Virus RNA in Infected Cells Reveals Temporally Distinct Host Factor Requirements.

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Olga V Viktorovskaya

2016-08-01

Full Text Available There are currently no vaccines or antivirals available for dengue virus infection, which can cause dengue hemorrhagic fever and death. A better understanding of the host pathogen interaction is required to develop effective therapies to treat DENV. In particular, very little is known about how cellular RNA binding proteins interact with viral RNAs. RNAs within cells are not naked; rather they are coated with proteins that affect localization, stability, translation and (for viruses replication.Seventy-nine novel RNA binding proteins for dengue virus (DENV were identified by cross-linking proteins to dengue viral RNA during a live infection in human cells. These cellular proteins were specific and distinct from those previously identified for poliovirus, suggesting a specialized role for these factors in DENV amplification. Knockdown of these proteins demonstrated their function as viral host factors, with evidence for some factors acting early, while others late in infection. Their requirement by DENV for efficient amplification is likely specific, since protein knockdown did not impair the cell fitness for viral amplification of an unrelated virus. The protein abundances of these host factors were not significantly altered during DENV infection, suggesting their interaction with DENV RNA was due to specific recruitment mechanisms. However, at the global proteome level, DENV altered the abundances of proteins in particular classes, including transporter proteins, which were down regulated, and proteins in the ubiquitin proteasome pathway, which were up regulated.The method for identification of host factors described here is robust and broadly applicable to all RNA viruses, providing an avenue to determine the conserved or distinct mechanisms through which diverse viruses manage the viral RNA within cells. This study significantly increases the number of cellular factors known to interact with DENV and reveals how DENV modulates and usurps

The host immune response to Clostridium difficile infection

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2013-01-01

Clostridium difficile infection (CDI) is the most common infectious cause of healthcare-acquired diarrhoea. Outcomes of C. difficile colonization are varied, from asymptomatic carriage to fulminant colitis and death, due in part to the interplay between the pathogenic virulence factors of the bacterium and the counteractive immune responses of the host. Secreted toxins A and B are the major virulence factors of C. difficile and induce a profound inflammatory response by intoxicating intestinal epithelial cells causing proinflammatory cytokine release. Host cell necrosis, vascular permeability and neutrophil infiltration lead to an elevated white cell count, profuse diarrhoea and in severe cases, dehydration, hypoalbuminaemia and toxic megacolon. Other bacterial virulence factors, including surface layer proteins and flagella proteins, are detected by host cell surface signal molecules that trigger downstream cell-mediated immune pathways. Human studies have identified a role for serum and faecal immunoglobulin levels in protection from disease, but the recent development of a mouse model of CDI has enabled studies into the precise molecular interactions that trigger the immune response during infection. Key effector molecules have been identified that can drive towards a protective anti-inflammatory response or a damaging proinflammatory response. The limitations of current antimicrobial therapies for CDI have led to the development of both active and passive immunotherapies, none of which have, as yet been formally approved for CDI. However, recent advances in our understanding of the molecular basis of host immune protection against CDI may provide an exciting opportunity for novel therapeutic developments in the future. PMID:25165542

Fungal invasion of normally non-phagocytic host cells.

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Scott G Filler

2006-12-01

Full Text Available Many fungi that cause invasive disease invade host epithelial cells during mucosal and respiratory infection, and subsequently invade endothelial cells during hematogenous infection. Most fungi invade these normally non-phagocytic host cells by inducing their own uptake. Candida albicans hyphae interact with endothelial cells in vitro by binding to N-cadherin on the endothelial cell surface. This binding induces rearrangement of endothelial cell microfilaments, which results in the endocytosis of the organism. The capsule of Cryptococcus neoformans is composed of glucuronoxylomannan, which binds specifically to brain endothelial cells, and appears to mediate both adherence and induction of endocytosis. The mechanisms by which other fungal pathogens induce their own uptake are largely unknown. Some angioinvasive fungi, such as Aspergillus species and the Zygomycetes, invade endothelial cells from the abluminal surface during the initiation of invasive disease, and subsequently invade the luminal surface of endothelial cells during hematogenous dissemination. Invasion of normally non-phagocytic host cells has different consequences, depending on the type of invading fungus. Aspergillus fumigatus blocks apoptosis of pulmonary epithelial cells, whereas Paracoccidioides brasiliensis induces apoptosis of epithelial cells. This review summarizes the mechanisms by which diverse fungal pathogens invade normally non-phagocytic host cells and discusses gaps in our knowledge that provide opportunities for future research.

Infection of Burkholderia cepacia induces homeostatic responses in the host for their prolonged survival: the microarray perspective.

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Vanitha Mariappan

Full Text Available Burkholderia cepacia is an opportunistic human pathogen associated with life-threatening pulmonary infections in immunocompromised individuals. Pathogenesis of B. cepacia infection involves adherence, colonisation, invasion, survival and persistence in the host. In addition, B. cepacia are also known to secrete factors, which are associated with virulence in the pathogenesis of the infection. In this study, the host factor that may be the cause of the infection was elucidated in human epithelial cell line, A549, that was exposed to live B. cepacia (mid-log phase and its secretory proteins (mid-log and early-stationary phases using the Illumina Human Ref-8 microarray platform. The non-infection A549 cells were used as a control. Expression of the host genes that are related to apoptosis, inflammation and cell cycle as well as metabolic pathways were differentially regulated during the infection. Apoptosis of the host cells and secretion of pro-inflammatory cytokines were found to be inhibited by both live B. cepacia and its secretory proteins. In contrast, the host cell cycle and metabolic processes, particularly glycolysis/glycogenesis and fatty acid metabolism were transcriptionally up-regulated during the infection. Our microarray analysis provided preliminary insights into mechanisms of B. cepacia pathogenesis. The understanding of host response to an infection would provide novel therapeutic targets both for enhancing the host's defences and repressing detrimental responses induced by the invading pathogen.

Host-derived viral transporter protein for nitrogen uptake in infected marine phytoplankton

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Chambouvet, Aurélie; Milner, David S.; Attah, Victoria; Terrado, Ramón; Lovejoy, Connie; Moreau, Hervé; Derelle, Évelyne; Richards, Thomas A.

2017-01-01

Phytoplankton community structure is shaped by both bottom–up factors, such as nutrient availability, and top–down processes, such as predation. Here we show that marine viruses can blur these distinctions, being able to amend how host cells acquire nutrients from their environment while also predating and lysing their algal hosts. Viral genomes often encode genes derived from their host. These genes may allow the virus to manipulate host metabolism to improve viral fitness. We identify in the genome of a phytoplankton virus, which infects the small green alga Ostreococcus tauri, a host-derived ammonium transporter. This gene is transcribed during infection and when expressed in yeast mutants the viral protein is located to the plasma membrane and rescues growth when cultured with ammonium as the sole nitrogen source. We also show that viral infection alters the nature of nitrogen compound uptake of host cells, by both increasing substrate affinity and allowing the host to access diverse nitrogen sources. This is important because the availability of nitrogen often limits phytoplankton growth. Collectively, these data show that a virus can acquire genes encoding nutrient transporters from a host genome and that expression of the viral gene can alter the nutrient uptake behavior of host cells. These results have implications for understanding how viruses manipulate the physiology and ecology of phytoplankton, influence marine nutrient cycles, and act as vectors for horizontal gene transfer. PMID:28827361

Disruptions of Host Immunity and Inflammation by Giardia Duodenalis: Potential Consequences for Co-Infections in the Gastro-Intestinal Tract

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James A. Cotton

2015-11-01

Full Text Available Giardia duodenalis (syn. G. intestinalis, or G. lamblia is a leading cause of waterborne diarrheal disease that infects hundreds of millions of people annually. Research on Giardia has greatly expanded within the last few years, and our understanding of the pathophysiology and immunology on this parasite is ever increasing. At peak infection, Giardia trophozoites induce pathophysiological responses that culminate in the development of diarrheal disease. However, human data has suggested that the intestinal mucosa of Giardia-infected individuals is devoid of signs of overt intestinal inflammation, an observation that is reproduced in animal models. Thus, our understanding of host inflammatory responses to the parasite remain incompletely understood and human studies and experimental data have produced conflicting results. It is now also apparent that certain Giardia infections contain mechanisms capable of modulating their host’s immune responses. As the oral route of Giardia infection is shared with many other gastrointestinal (GI pathogens, co-infections may often occur, especially in places with poor sanitation and/or improper treatment of drinking water. Moreover, Giardia infections may modulate host immune responses and have been found to protect against the development of diarrheal disease in developing countries. The following review summarizes our current understanding of the immunomodulatory mechanisms of Giardia infections and their consequences for the host, and highlights areas for future research. Potential implications of these immunomodulatory effects during GI co-infection are also discussed.

Cd1b-Mediated T Cell Recognition of a Glycolipid Antigen Generated from Mycobacterial Lipid and Host Carbohydrate during Infection

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Moody, D. Branch; Guy, Mark R.; Grant, Ethan; Cheng, Tan-Yun; Brenner, Michael B.; Besra, Gurdyal S.; Porcelli, Steven A.

2000-01-01

T cells recognize microbial glycolipids presented by CD1 proteins, but there is no information regarding the generation of natural glycolipid antigens within infected tissues. Therefore, we determined the molecular basis of CD1b-restricted T cell recognition of mycobacterial glycosylated mycolates, including those produced during tissue infection in vivo. Transfection of the T cell receptor (TCR) α and β chains from a glucose monomycolate (GMM)-specific T cell line reconstituted GMM recognition in TCR-deficient T lymphoblastoma cells. This TCR-mediated response was highly specific for natural mycobacterial glucose-6-O-(2R, 3R) monomycolate, including the precise structure of the glucose moiety, the stereochemistry of the mycolate lipid, and the linkage between the carbohydrate and the lipid. Mycobacterial production of antigenic GMM absolutely required a nonmycobacterial source of glucose that could be supplied by adding glucose to media at concentrations found in mammalian tissues or by infecting tissue in vivo. These results indicate that mycobacteria synthesized antigenic GMM by coupling mycobacterial mycolates to host-derived glucose. Specific T cell recognition of an epitope formed by interaction of host and pathogen biosynthetic pathways provides a mechanism for immune response to those pathogenic mycobacteria that have productively infected tissues, as distinguished from ubiquitous, but innocuous, environmental mycobacteria. PMID:11015438

Potential for Monitoring Gut Microbiota for Diagnosing Infections and Graft-versus-Host Disease in Cancer and Stem Cell Transplant Patients.

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Koh, Andrew Y

2017-11-01

Gut microbiota, the collective community of microorganisms inhabiting the intestine, have been shown to provide many beneficial functions for the host. Recent advances in next-generation sequencing and advanced molecular biology approaches have allowed researchers to identify gut microbiota signatures associated with disease processes and, in some cases, establish causality and elucidate underlying mechanisms. This report reviews 3 commonly used methods for studying the gut microbiota and microbiome (the collective genomes of the gut microorganisms): 16S rRNA gene sequencing, bacterial group or species-specific quantitative polymerase chain reaction (qPCR), and metagenomic shotgun sequencing (MSS). The technical approaches and resources needed for each approach are outlined, and advantages and disadvantages for each approach are summarized. The findings regarding the role of the gut microbiota in the health of patients with cancer and stem cell transplant (SCT) patients (specifically in modulating the development of gut-derived bacterial infections and a posttransplant immune-mediated complication known as graft-vs-host-disease) are reviewed. Finally, there is discussion of the potential viability of these approaches in the actual clinical treatment of cancer and SCT patients. Advances in next-generation sequencing have revolutionized our understanding of the importance of the gut microbiome to human health. Both 16S rRNA gene sequencing and MSS are currently too labor-intensive or computationally burdensome to incorporate into real-time clinical monitoring of gut microbiomes. Yet, the lessons learned from these technologies could be adapted to currently used methods (e.g., qPCR) that could then be rigorously tested in the clinical care of these patients. © 2017 American Association for Clinical Chemistry.

Lymphocytes and macrophages are infected by Theileria equi, but T cells and B cells are not required to establish infection in vivo.

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Joshua D Ramsay

Full Text Available Theileria equi has a biphasic life cycle in horses, with a period of intraleukocyte development followed by patent erythrocytic parasitemia that causes acute and sometimes fatal hemolytic disease. Unlike Theileria spp. that infect cattle (Theileria parva and Theileria annulata, the intraleukocyte stage (schizont of Theileria equi does not cause uncontrolled host cell proliferation or other significant pathology. Nevertheless, schizont-infected leukocytes are of interest because of their potential to alter host cell function and because immune responses directed against this stage could halt infection and prevent disease. Based on cellular morphology, Theileria equi has been reported to infect lymphocytes in vivo and in vitro, but the specific phenotype of schizont-infected cells has yet to be defined. To resolve this knowledge gap in Theileria equi pathogenesis, peripheral blood mononuclear cells were infected in vitro and the phenotype of infected cells determined using flow cytometry and immunofluorescence microscopy. These experiments demonstrated that the host cell range of Theileria equi was broader than initially reported and included B lymphocytes, T lymphocytes and monocyte/macrophages. To determine if B and T lymphocytes were required to establish infection in vivo, horses affected with severe combined immunodeficiency (SCID, which lack functional B and T lymphocytes, were inoculated with Theileria equi sporozoites. SCID horses developed patent erythrocytic parasitemia, indicating that B and T lymphocytes are not necessary to complete the Theileria equi life cycle in vivo. These findings suggest that the factors mediating Theileria equi leukocyte invasion and intracytoplasmic differentiation are common to several leukocyte subsets and are less restricted than for Theileria annulata and Theileria parva. These data will greatly facilitate future investigation into the relationships between Theileria equi leukocyte tropism and pathogenesis

Distinct pathogenesis and host responses during infection of C. elegans by P. aeruginosa and S. aureus.

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Irazoqui, Javier E; Troemel, Emily R; Feinbaum, Rhonda L; Luhachack, Lyly G; Cezairliyan, Brent O; Ausubel, Frederick M

2010-07-01

The genetically tractable model host Caenorhabditis elegans provides a valuable tool to dissect host-microbe interactions in vivo. Pseudomonas aeruginosa and Staphylococcus aureus utilize virulence factors involved in human disease to infect and kill C. elegans. Despite much progress, virtually nothing is known regarding the cytopathology of infection and the proximate causes of nematode death. Using light and electron microscopy, we found that P. aeruginosa infection entails intestinal distention, accumulation of an unidentified extracellular matrix and P. aeruginosa-synthesized outer membrane vesicles in the gut lumen and on the apical surface of intestinal cells, the appearance of abnormal autophagosomes inside intestinal cells, and P. aeruginosa intracellular invasion of C. elegans. Importantly, heat-killed P. aeruginosa fails to elicit a significant host response, suggesting that the C. elegans response to P. aeruginosa is activated either by heat-labile signals or pathogen-induced damage. In contrast, S. aureus infection causes enterocyte effacement, intestinal epithelium destruction, and complete degradation of internal organs. S. aureus activates a strong transcriptional response in C. elegans intestinal epithelial cells, which aids host survival during infection and shares elements with human innate responses. The C. elegans genes induced in response to S. aureus are mostly distinct from those induced by P. aeruginosa. In contrast to P. aeruginosa, heat-killed S. aureus activates a similar response as live S. aureus, which appears to be independent of the single C. elegans Toll-Like Receptor (TLR) protein. These data suggest that the host response to S. aureus is possibly mediated by pathogen-associated molecular patterns (PAMPs). Because our data suggest that neither the P. aeruginosa nor the S. aureus-triggered response requires canonical TLR signaling, they imply the existence of unidentified mechanisms for pathogen detection in C. elegans, with

Distinct pathogenesis and host responses during infection of C. elegans by P. aeruginosa and S. aureus.

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Javier E Irazoqui

2010-07-01

Full Text Available The genetically tractable model host Caenorhabditis elegans provides a valuable tool to dissect host-microbe interactions in vivo. Pseudomonas aeruginosa and Staphylococcus aureus utilize virulence factors involved in human disease to infect and kill C. elegans. Despite much progress, virtually nothing is known regarding the cytopathology of infection and the proximate causes of nematode death. Using light and electron microscopy, we found that P. aeruginosa infection entails intestinal distention, accumulation of an unidentified extracellular matrix and P. aeruginosa-synthesized outer membrane vesicles in the gut lumen and on the apical surface of intestinal cells, the appearance of abnormal autophagosomes inside intestinal cells, and P. aeruginosa intracellular invasion of C. elegans. Importantly, heat-killed P. aeruginosa fails to elicit a significant host response, suggesting that the C. elegans response to P. aeruginosa is activated either by heat-labile signals or pathogen-induced damage. In contrast, S. aureus infection causes enterocyte effacement, intestinal epithelium destruction, and complete degradation of internal organs. S. aureus activates a strong transcriptional response in C. elegans intestinal epithelial cells, which aids host survival during infection and shares elements with human innate responses. The C. elegans genes induced in response to S. aureus are mostly distinct from those induced by P. aeruginosa. In contrast to P. aeruginosa, heat-killed S. aureus activates a similar response as live S. aureus, which appears to be independent of the single C. elegans Toll-Like Receptor (TLR protein. These data suggest that the host response to S. aureus is possibly mediated by pathogen-associated molecular patterns (PAMPs. Because our data suggest that neither the P. aeruginosa nor the S. aureus-triggered response requires canonical TLR signaling, they imply the existence of unidentified mechanisms for pathogen detection in C

Viral/Host interaction in viral infections

International Nuclear Information System (INIS)

Le Grand, R.

2006-01-01

The major objectives of the Neuro-virology Department (SNV for 'Service de Neurovirologie') are related to the study of host/pathogen interactions, particularly during primate lentiviral infections. Various experimental models have been developed such as non-human primates infected with the HIV-related simian immunodeficiency viruses (SIV), as an animal model of human AIDS. The current research programs of the SNV following four main directions: 1) Study of the pathogenesis of primate lentiviral infection, including mucosal transmission of HIV/SIV, primary infection, dissemination to various reservoirs, neuro-pathogenesis and hematopoietic disorders; 2) Prevention of HIV transmission, particularly through vaccination but also by means of microbicides applied to genital mucosa and post-exposure treatment with antiviral drugs; 3) Cellular and molecular pharmacology of new antiviral compounds; 4) Development of new primate models of human hematological disorders like chronic myeloid leukemia cells and development on new gene transfer in hematopoietic cells based on the use of lentiviral vectors Main programs of the SNV will be presented as well as the perspective focused on the use of non invasive in vivo imaging approaches for the exploration of immune and hematopoietic cells

Viral/Host interaction in viral infections

Energy Technology Data Exchange (ETDEWEB)

Le Grand, R. [CEA Fontenay-aux-Roses, Service de Neurovirologie, 92 (France)

2006-07-01

The major objectives of the Neuro-virology Department (SNV for 'Service de Neurovirologie') are related to the study of host/pathogen interactions, particularly during primate lentiviral infections. Various experimental models have been developed such as non-human primates infected with the HIV-related simian immunodeficiency viruses (SIV), as an animal model of human AIDS. The current research programs of the SNV following four main directions: 1) Study of the pathogenesis of primate lentiviral infection, including mucosal transmission of HIV/SIV, primary infection, dissemination to various reservoirs, neuro-pathogenesis and hematopoietic disorders; 2) Prevention of HIV transmission, particularly through vaccination but also by means of microbicides applied to genital mucosa and post-exposure treatment with antiviral drugs; 3) Cellular and molecular pharmacology of new antiviral compounds; 4) Development of new primate models of human hematological disorders like chronic myeloid leukemia cells and development on new gene transfer in hematopoietic cells based on the use of lentiviral vectors Main programs of the SNV will be presented as well as the perspective focused on the use of non invasive in vivo imaging approaches for the exploration of immune and hematopoietic cells.

Contribution of MS-based proteomics to the understanding of Herpes Simplex Virus type 1 interaction with host cells

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Enrique eSantamaría

2012-03-01

Full Text Available Like other DNA viruses, Herpes Simplex Virus type 1 (HSV-1 replicates and proliferates in host cells continuously modulating the host molecular environment. Following a sophisticated temporal expression pattern, HSV-1 encodes at least 89 multifunctional proteins that interplay with and modify the host cell proteome. During the last decade, advances in mass spectrometry applications coupled to the development of proteomic separation methods have allowed to partially monitor the impact of HSV-1 infection in human cells. In this review, we discuss the current use of different proteome fractionation strategies to define HSV-1 targets on two major application areas: i viral protein interactomics to decipher viral protein interactions in host cells and ii differential quantitative proteomics to analyse the virally induced changes in the cellular proteome. Moreover, we will also discuss the potential application of high throughput proteomic approaches to study global proteome dynamics and also post-translational modifications in HSV-1-infected cells, what will greatly improved our molecular knowledge of HSV-1 infection.

Shigella flexneri infection in Caenorhabditis elegans: cytopathological examination and identification of host responses.

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Divya T George

Full Text Available The Gram-negative bacterium Shigella flexneri is the causative agent of shigellosis, a diarrhoeal disease also known as bacillary dysentery. S. flexneri infects the colonic and rectal epithelia of its primate host and induces a cascade of inflammatory responses that culminates in the destruction of the host intestinal lining. Molecular characterization of host-pathogen interactions in this infection has been challenging due to the host specificity of S. flexneri strains, as it strictly infects humans and non-human primates. Recent studies have shown that S. flexneri infects the soil dwelling nematode Caenorhabditis elegans, however, the interactions between S. flexneri and C. elegans at the cellular level and the cause of nematode death are unknown. Here we attempt to gain insight into the complex host-pathogen interactions between S. flexneri and C. elegans. Using transmission electron microscopy, we show that live S. flexneri cells accumulate in the nematode intestinal lumen, produce outer membrane vesicles and invade nematode intestinal cells. Using two-dimensional differential in-gel electrophoresis we identified host proteins that are differentially expressed in response to S. flexneri infection. Four of the identified genes, aco-1, cct-2, daf-19 and hsp-60, were knocked down using RNAi and ACO-1, CCT-2 and DAF-19, which were identified as up-regulated in response to S. flexneri infection, were found to be involved in the infection process. aco-1 RNAi worms were more resistant to S. flexneri infection, suggesting S. flexneri-mediated disruption of host iron homeostasis. cct-2 and daf-19 RNAi worms were more susceptible to infection, suggesting that these genes are induced as a protective mechanism by C. elegans. These observations further our understanding of the processes involved in S. flexneri infection of C. elegans, which is immensely beneficial to the routine use of this new in vivo model to study S. flexneri pathogenesis.

Unfolding Role of a Danger Molecule Adenosine Signaling in Modulation of Microbial Infection and Host Cell Response

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Jaden S. Lee

2018-01-01

Full Text Available Ectonucleotidases CD39 and CD73, specific nucleotide metabolizing enzymes located on the surface of the host, can convert a pro-inflammatory environment driven by a danger molecule extracellular-ATP to an adenosine-mediated anti-inflammatory milieu. Accordingly, CD39/CD73 signaling has been strongly implicated in modulating the intensity, duration, and composition of purinergic danger signals delivered to host. Recent studies have eluted potential roles for CD39 and CD73 in selective triggering of a variety of host immune cells and molecules in the presence of pathogenic microorganisms or microbial virulence molecules. Growing evidence also suggests that CD39 and CD73 present complimentary, but likely differential, actions against pathogens to shape the course and severity of microbial infection as well as the associated immune response. Similarly, adenosine receptors A2A and A2B have been proposed to be major immunomodulators of adenosine signaling during chronic inflammatory conditions induced by opportunistic pathogens, such as oral colonizer Porphyromonas gingivalis. Therefore, we here review the recent studies that demonstrate how complex network of molecules in the extracellular adenosine signaling machinery and their interactions can reshape immune responses and may also be targeted by opportunistic pathogens to establish successful colonization in human mucosal tissues and modulate the host immune response.

The membrane as the gatekeeper of infection: Cholesterol in host-pathogen interaction.

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Kumar, G Aditya; Jafurulla, Md; Chattopadhyay, Amitabha

2016-09-01

The cellular plasma membrane serves as a portal for the entry of intracellular pathogens. An essential step for an intracellular pathogen to gain entry into a host cell therefore is to be able to cross the cell membrane. In this review, we highlight the role of host membrane cholesterol in regulating the entry of intracellular pathogens using insights obtained from work on the interaction of Leishmania and Mycobacterium with host cells. The entry of these pathogens is known to be dependent on host membrane cholesterol. Importantly, pathogen entry is inhibited either upon depletion (or complexation), or enrichment of membrane cholesterol. In other words, an optimum level of host membrane cholesterol is necessary for efficient infection by pathogens. In this overall context, we propose a general mechanism, based on cholesterol-induced conformational changes, involving cholesterol binding sites in host cell surface receptors that are implicated in this process. A therapeutic strategy targeting modulation of membrane cholesterol would have the advantage of avoiding the commonly encountered problem of drug resistance in tackling infection by intracellular pathogens. Insights into the role of host membrane cholesterol in pathogen entry would be instrumental in the development of novel therapeutic strategies to effectively tackle intracellular pathogenesis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Mycoplasma agalactiae Induces Cytopathic Effects in Infected Cells Cultured In Vitro.

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Shrilakshmi Hegde

Full Text Available Mycoplasma agalactiae is the etiological agent of the contagious agalactia syndrome in sheep and goats and causes significant economic losses worldwide. Yet the mechanism of pathogenesis is largely unknown. Even whole-genome sequence analysis of its pathogenic type strain did not lead to any conclusions regarding its virulence or pathogenicity factors. Although inflammation and tissue destruction at the local site of M. agalactiae infection are largely considered as effects of the host immune response, the direct effect of the agent on host cells is not completely understood. The aim of this study was to investigate the effect of M. agalactiae infection on the quality and viability of host cells in vitro. Changes in cell morphology including cell elongation, cytoplasm shrinkage and membrane blebbing were observed in infected HeLa cells. Chromatin condensation and increased caspase-3 cleavage in infected HeLa cells 48 h after infection suggests an apoptosis-like phenomenon in M. agalactiae-infected cells. In compliance with these results, decreased viability and cell lysis of M. agalactiae-infected HeLa cells was also observed. Measurement of the amount of LDH released after M. agalactiae infection revealed a time- and dose-dependent increase in HeLa cell lysis. A significant decrease in LDH released after gentamicin treatment of infected cells confirmed the major role of cytadherent M. agalactiae in inducing host cell lysis. This is the first study illustrating M. agalactiae's induction of cytopathic effects in infected HeLa cells. Further detailed investigation of infected host tissue for apoptotic markers might demonstrate the association between M. agalactiae-induced host cell lysis and the tissue destruction observed during M. agalactiae natural infection.

Nuclear entry of poliovirus protease-polymerase precursor 3CD: implications for host cell transcription shut-off

International Nuclear Information System (INIS)

Sharma, Rakhi; Raychaudhuri, Santanu; Dasgupta, Asim

2004-01-01

Host cell transcription mediated by all three RNA polymerases is rapidly inhibited after infection of mammalian cells with poliovirus (PV). Both genetic and biochemical studies have shown that the virus-encoded protease 3C cleaves the TATA-binding protein and other transcription factors at glutamine-glycine sites and is directly responsible for host cell transcription shut-off. PV replicates in the cytoplasm of infected cells. To shut-off host cell transcription, 3C or a precursor of 3C must enter the nucleus of infected cells. Although the 3C protease itself lacks a nuclear localization signal (NLS), amino acid sequence examination of 3D identified a potential single basic type NLS, KKKRD, spanning amino acids 125-129 within this polypeptide. Thus, a plausible scenario is that 3C enters the nucleus in the form of its precursor, 3CD, which then generates 3C by auto-proteolysis ultimately leading to cleavage of transcription factors in the nucleus. Using transient transfection of enhanced green fluorescent protein (EGFP) fusion polypeptides, we demonstrate here that both 3CD and 3D are capable of entering the nucleus in PV-infected cells. However, both polypeptides remain in the cytoplasm in uninfected HeLa cells. Mutagenesis of the NLS sequence in 3D prevents nuclear entry of 3D and 3CD in PV-infected cells. We also demonstrate that 3CD can be detected in the nuclear fraction from PV-infected HeLa cells as early as 2 h postinfection. Significant amount of 3CD is found associated with the nuclear fraction by 3-4 h of infection. Taken together, these results suggest that both the 3D NLS and PV infection are required for the entry of 3CD into the nucleus and that this may constitute a means by which viral protease 3C is delivered into the nucleus leading to host cell transcription shut-off

Conserved host response to highly pathogenic avian influenza virus infection in human cell culture, mouse and macaque model systems

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McDermott Jason E

2011-11-01

Full Text Available Abstract Background Understanding host response to influenza virus infection will facilitate development of better diagnoses and therapeutic interventions. Several different experimental models have been used as a proxy for human infection, including cell cultures derived from human cells, mice, and non-human primates. Each of these systems has been studied extensively in isolation, but little effort has been directed toward systematically characterizing the conservation of host response on a global level beyond known immune signaling cascades. Results In the present study, we employed a multivariate modeling approach to characterize and compare the transcriptional regulatory networks between these three model systems after infection with a highly pathogenic avian influenza virus of the H5N1 subtype. Using this approach we identified functions and pathways that display similar behavior and/or regulation including the well-studied impact on the interferon response and the inflammasome. Our results also suggest a primary response role for airway epithelial cells in initiating hypercytokinemia, which is thought to contribute to the pathogenesis of H5N1 viruses. We further demonstrate that we can use a transcriptional regulatory model from the human cell culture data to make highly accurate predictions about the behavior of important components of the innate immune system in tissues from whole organisms. Conclusions This is the first demonstration of a global regulatory network modeling conserved host response between in vitro and in vivo models.

Cellular Aspects of Shigella Pathogenesis: Focus on the Manipulation of Host Cell Processes.

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Killackey, Samuel A; Sorbara, Matthew T; Girardin, Stephen E

2016-01-01

Shigella is a Gram-negative bacterium that is responsible for shigellosis. Over the years, the study of Shigella has provided a greater understanding of how the host responds to bacterial infection, and how bacteria have evolved to effectively counter the host defenses. In this review, we provide an update on some of the most recent advances in our understanding of pivotal processes associated with Shigella infection, including the invasion into host cells, the metabolic changes that occur within the bacterium and the infected cell, cell-to-cell spread mechanisms, autophagy and membrane trafficking, inflammatory signaling and cell death. This recent progress sheds a new light into the mechanisms underlying Shigella pathogenesis, and also more generally provides deeper understanding of the complex interplay between host cells and bacterial pathogens in general.

Genetic reprogramming of host cells by bacterial pathogens.

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Tran Van Nhieu, Guy; Arbibe, Laurence

2009-10-29

During the course of infection, pathogens often induce changes in gene expression in host cells and these changes can be long lasting and global or transient and of limited amplitude. Defining how, when, and why bacterial pathogens reprogram host cells represents an exciting challenge that opens up the opportunity to grasp the essence of pathogenesis and its molecular details.

Host nutrition alters the variance in parasite transmission potential.

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Vale, Pedro F; Choisy, Marc; Little, Tom J

2013-04-23

The environmental conditions experienced by hosts are known to affect their mean parasite transmission potential. How different conditions may affect the variance of transmission potential has received less attention, but is an important question for disease management, especially if specific ecological contexts are more likely to foster a few extremely infectious hosts. Using the obligate-killing bacterium Pasteuria ramosa and its crustacean host Daphnia magna, we analysed how host nutrition affected the variance of individual parasite loads, and, therefore, transmission potential. Under low food, individual parasite loads showed similar mean and variance, following a Poisson distribution. By contrast, among well-nourished hosts, parasite loads were right-skewed and overdispersed, following a negative binomial distribution. Abundant food may, therefore, yield individuals causing potentially more transmission than the population average. Measuring both the mean and variance of individual parasite loads in controlled experimental infections may offer a useful way of revealing risk factors for potential highly infectious hosts.

Screening for potential anti-infective agents towards Burkholderia pseudomallei infection

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Eng, Su Anne; Nathan, Sheila

2014-09-01

The established treatment for melioidosis is antibiotic therapy. However, a constant threat to this form of treatment is resistance development of the causative agent, Burkholderia pseudomallei, towards antibiotics. One option to circumvent this threat of antibiotic resistance is to search for new alternative anti-infectives which target the host innate immune system and/or bacterial virulence. In this study, 29 synthetic compounds were evaluated for their potential to increase the lifespan of an infected host. The nematode Caenorhabditis elegans was adopted as the infection model as its innate immune pathways are homologous to humans. Screens were performed in a liquid-based survival assay containing infected worms exposed to individual compounds and survival of untreated and compound-treated worms were compared. A primary screen identified nine synthetic compounds that extended the lifespan of B. pseudomallei-infected worms. Subsequently, a disc diffusion test was performed on these selected compounds to delineate compounds into those that enhanced the survival of worms via antimicrobial activity i.e. reducing the number of infecting bacteria, or into those that did not target pathogen viability. Out of the nine hits selected, two demonstrated antimicrobial effects on B. pseudomallei. Therefore, the findings from this study suggest that the other seven identified compounds are potential anti-infectives which could protect a host against B. pseudomallei infection without developing the risk of drug resistance.

Rhodiolae Kirliowii Radix et Rhizoma and Crataegus pinnatifida Fructus Extracts Effectively Inhibit BK Virus and JC Virus Infection of Host Cells

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San-Yuan Chen

2017-01-01

Full Text Available The human polyomaviruses BK (BKPyV and JC (JCPyV are ubiquitous pathogens long associated with severe disease in immunocompromised individuals. BKPyV causes polyomavirus-associated nephropathy and hemorrhagic cystitis, whereas JCPyV is the causative agent of the fatal demyelinating disease progressive multifocal leukoencephalopathy. No effective therapies targeting these viruses are currently available. The goal of this study was to identify Chinese medicinal herbs with antiviral activity against BKPyV and JCPyV. We screened extracts of Chinese medicinal herbs for the ability to inhibit hemagglutination by BKPyV and JCPyV virus-like particles (VLPs and the ability to inhibit BKPyV and JCPyV binding and infection of host cells. Two of the 40 herbal extracts screened, Rhodiolae Kirliowii Radix et Rhizoma and Crataegus pinnatifida Fructus, had hemagglutination inhibition activity on BKPyV and JCPyV VLPs and further inhibited infection of the cells by BKPyV and JCPyV, as evidenced by reduced expression of viral proteins in BKPyV-infected and JCPyV-infected cells after treatment with Rhodiolae Kirliowii Radix et Rhizoma or Crataegus pinnatifida Fructus extract. The results in this work show that both Rhodiolae Kirliowii Radix et Rhizoma and Crataegus pinnatifida Fructus may be sources of potential antiviral compounds for treating BKPyV and JCPyV infections.

Potential Cellular Signatures of Viral Infections in Human Hematopoietic Cells

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J. Mikovits

2001-01-01

Full Text Available Expression profiling of cellular genes was performed using a 10,000 cDNA human gene array in order to identify expression changes following chronic infection of human hematopoietic cells with Kapsosi’s Sarcoma -associated Virus (KSHV also known as Human Herpesvirus 8 (HHV8 and Human T cell leukemia virus-1 (HTLV-1. We performed cell-free {\\it in vitro} infection of primary bone marrow derived CD34+ cells using semi-purified HHV8 and a mature IL-2 dependent T cell line, KIT 225, using highly concentrated viral stocks prepared from an infectious molecular clone of HTLV-1. Thirty days post infection, mRNA was isolated from infected cultures and uninfected controls and submitted for microarray analysis. More than 400 genes were differentially expressed more than two-fold following HHV8 infection of primary bone marrow derived CD34+ cells. Of these 400, interferon regulatory factor 4 (IRF4, cyclin B2, TBP-associated factor, eukaryotic elongation factor and pim 2 were up-regulated more than 3.5 fold. In contrast, less than 100 genes were differentially expressed more than two-fold following chronic infection of a mature T cell line with HTLV-1. Of these, only cdc7 was up-regulated more than 3.5 fold. These data may provide insight into cellular signatures of infection useful for diagnosis of infection as well as potential targets for therapeutic intervention.

Analysis of Host-Takeover During SPO1 Infection of Bacillus subtilis.

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Stewart, Charles R

2018-01-01

When Bacillus subtilis is infected by bacteriophage SPO1, the phage directs the remodeling of the host cell, converting it into a factory for phage reproduction. Much synthesis of host DNA, RNA, and protein is shut off, and cell division is prevented. Here I describe the protocols by which we have demonstrated those processes, and identified the roles played by specific SPO1 gene products in causing those processes.

Epigenetic silencing of host cell defense genes enhances intracellular survival of the rickettsial pathogen Anaplasma phagocytophilum.

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Jose C Garcia-Garcia

2009-06-01

Full Text Available Intracellular bacteria have evolved mechanisms that promote survival within hostile host environments, often resulting in functional dysregulation and disease. Using the Anaplasma phagocytophilum-infected granulocyte model, we establish a link between host chromatin modifications, defense gene transcription and intracellular bacterial infection. Infection of THP-1 cells with A. phagocytophilum led to silencing of host defense gene expression. Histone deacetylase 1 (HDAC1 expression, activity and binding to the defense gene promoters significantly increased during infection, which resulted in decreased histone H3 acetylation in infected cells. HDAC1 overexpression enhanced infection, whereas pharmacologic and siRNA HDAC1 inhibition significantly decreased bacterial load. HDAC2 does not seem to be involved, since HDAC2 silencing by siRNA had no effect on A. phagocytophilum intracellular propagation. These data indicate that HDAC up-regulation and epigenetic silencing of host cell defense genes is required for A. phagocytophilum infection. Bacterial epigenetic regulation of host cell gene transcription could be a general mechanism that enhances intracellular pathogen survival while altering cell function and promoting disease.

Kupffer cell complement receptor clearance function and host defense.

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Loegering, D J

1986-01-01

Kupffer cells are well known to be important for normal host defense function. The development of methods to evaluate the in vivo function of specific receptors on Kupffer cells has made it possible to assess the role of these receptors in host defense. The rationale for studying complement receptors is based on the proposed important role of these receptors in host defense and on the observation that the hereditary deficiency of a complement receptor is associated with recurrent severe bacterial infections. The studies reviewed here demonstrate that forms of injury that are associated with depressed host defense including thermal injury, hemorrhagic shock, trauma, and surgery also cause a decrease in complement receptor clearance function. This decrease in Kupffer cell receptor clearance function was shown not to be the result of depressed hepatic blood flow or depletion of complement components. Complement receptor function was also depressed following the phagocytosis of particulates that are known to depress Kupffer cell host defense function. Endotoxemia and bacteremia also were associated with a depression of complement receptor function. Complement receptor function was experimentally depressed in uninjured animals by the phagocytosis of IgG-coated erythrocytes. There was a close association between the depression of complement receptor clearance function and increased susceptibility to the lethal effects of endotoxin and bacterial infection. These studies support the hypotheses that complement receptors on Kupffer cells are important for normal host defense and that depression of the function of these receptors impairs host defense.

Enforcing host cell polarity: an apicomplexan parasite strategy towards dissemination.

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Baumgartner, Martin

2011-08-01

The propagation of apicomplexan parasites through transmitting vectors is dependent on effective dissemination of parasites inside the mammalian host. Intracellular Toxoplasma and Theileria parasites face the challenge that their spread inside the host depends in part on the motile capacities of their host cells. In response, these parasites influence the efficiency of dissemination by altering adhesive and/or motile properties of their host cells. Theileria parasites do so by targeting signalling pathways that control host cell actin dynamics. The resulting enforced polar host cell morphology facilitates motility and invasiveness, by establishing focal adhesion and invasion structures at the leading edge of the infected cell. This parasite strategy highlights mechanisms of motility regulation that are also likely relevant for immune or cancer cell motility. Copyright © 2011 Elsevier Ltd. All rights reserved.

Differential stability of host mRNAs in Friend erythroleukemia cells infected with herpes simplex virus type 1

International Nuclear Information System (INIS)

Mayman, B.A.; Nishioka, Y.

1985-01-01

The consequences of herpes simplex virus type 1 infection on cellular macromolecules were investigated in Friend erythroleukemia cells. The patterns of protein synthesis, examined by polyacrylamide gel electrophoresis, demonstrated that by 4 h postinfection the synthesis of many host proteins, with the exception of histones, was inhibited. Examination of the steady-state level of histone H3 mRNA by molecular hybridization of total RNA to a cloned mouse histone H3 complementary DNA probe demonstrated that the ratio of histone H3 mRNA to total RNA remained unchanged for the first 4 h postinfection. In contrast, the steady-state levels of globin and actin mRNAs decreased progressively at early intervals postinfection. Studies on RNA synthesis in isolated nuclei demonstrated that the transcription of the histone H3 gene was inhibited to approximately the same extent as that of actin gene. It was concluded that the stabilization of preexisting histone H3 mRNA was responsible for the persistence of H3 mRNA and histone protein synthesis in herpes simplex virus type 1-infected Friend erythroleukemia cells. The possible mechanisms influencing the differential stability of host mRNAs during the course of productive infection with herpes simplex virus type 1 are discussed

Synthetic immunostimulatory glycans interference with host cell apoptosis upon of Toxoplasma gondii infection, in vitro

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S.H. Eassa

2017-06-01

Full Text Available Toxoplasmosis is a protozoan infection of humans and animals caused by Toxoplasma gondii, and it’s continuous public health and food safety issue. The tachyzoites (Tg of T. gondii are the most important stage, as they come in direct contact with immune cells such as a macrophage. Tg can modulate and prevent apoptosis of immune cells while promoting survival of the pathogen. Infections caused by Tg can be eradicated if immune cells could stimulate apoptosis and kill pathogens upon exposure. Apoptosis is characterized by the release of mediators, namely Caspases (Cas. New means are required for inducing apoptosis and enhance immunity in the infected host cell to control toxoplasmosis. The present study investigated whether Synthetic Immuno-stimulatory Glycans (SIGs influence Cas and Nitric oxide (NO release and led to Tg damage. Galβ1-3Gal-PAA-fluor (SIG1, Fucα1-4GlcNAcβ-PAA-fluor (SIG2 and GlcNAcβ1-3GalNAcα-PAA-fluor (SIG3 constituted samples studied principally. Murine macrophage had been exposed to the Tg then the SIGs effects on Cas and NO production were determined after 20 hours of pathogen phagocytosis. Here we report that the SIGs had potent in vitro activity against T. gondii; SIG2 was more effective than SIG1 and SIG3, representative by SIG2 treated infected macrophages can induced infected macrophages to release Cas1, 3, and 9. Maximum production of NO by infected macrophages was noticed following the expoxure to all SIGs. Therefore the present study provided the method for the selection of SIGs ligands bearing immunostimulatory factor and apoptotic stimuli properties.

Establishment of human papillomavirus infection requires cell cycle progression.

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Dohun Pyeon

2009-02-01

Full Text Available Human papillomaviruses (HPVs are DNA viruses associated with major human cancers. As such there is a strong interest in developing new means, such as vaccines and microbicides, to prevent HPV infections. Developing the latter requires a better understanding of the infectious life cycle of HPVs. The HPV infectious life cycle is closely linked to the differentiation state of the stratified epithelium it infects, with progeny virus only made in the terminally differentiating suprabasal compartment. It has long been recognized that HPV must first establish its infection within the basal layer of stratified epithelium, but why this is the case has not been understood. In part this restriction might reflect specificity of expression of entry receptors. However, this hypothesis could not fully explain the differentiation restriction of HPV infection, since many cell types can be infected with HPVs in monolayer cell culture. Here, we used chemical biology approaches to reveal that cell cycle progression through mitosis is critical for HPV infection. Using infectious HPV16 particles containing the intact viral genome, G1-synchronized human keratinocytes as hosts, and early viral gene expression as a readout for infection, we learned that the recipient cell must enter M phase (mitosis for HPV infection to take place. Late M phase inhibitors had no effect on infection, whereas G1, S, G2, and early M phase cell cycle inhibitors efficiently prevented infection. We conclude that host cells need to pass through early prophase for successful onset of transcription of the HPV encapsidated genes. These findings provide one reason why HPVs initially establish infections in the basal compartment of stratified epithelia. Only this compartment of the epithelium contains cells progressing through the cell cycle, and therefore it is only in these cells that HPVs can establish their infection. By defining a major condition for cell susceptibility to HPV infection, these

Coronavirus infection of polarized epithelial cells

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Rossen, J W; Horzinek, M C; Rottier, P J

1995-01-01

Epithelial cells are the first host cells to be infected by incoming c oronaviruses. Recent observations in vitro show that coronaviruses are released from a specific side of these polarized cells, and this polarized release might be important for the spread of the infection in vivo. Mechanisms for

Characterization of an Sf-rhabdovirus-negative Spodoptera frugiperda cell line as an alternative host for recombinant protein production in the baculovirus-insect cell system.

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Maghodia, Ajay B; Geisler, Christoph; Jarvis, Donald L

2016-06-01

Cell lines derived from the fall armyworm, Spodoptera frugiperda (Sf), are widely used as hosts for recombinant protein production in the baculovirus-insect cell system (BICS). However, it was recently discovered that these cell lines are contaminated with a virus, now known as Sf-rhabdovirus [1]. The detection of this adventitious agent raised a potential safety issue that could adversely impact the BICS as a commercial recombinant protein production platform. Thus, we examined the properties of Sf-RVN, an Sf-rhabdovirus-negative Sf cell line, as a potential alternative host. Nested RT-PCR assays showed Sf-RVN cells had no detectable Sf-rhabdovirus over the course of 60 passages in continuous culture. The general properties of Sf-RVN cells, including their average growth rates, diameters, morphologies, and viabilities after baculovirus infection, were virtually identical to those of Sf9 cells. Baculovirus-infected Sf-RVN and Sf9 cells produced equivalent levels of three recombinant proteins, including an intracellular prokaryotic protein and two secreted eukaryotic glycoproteins, and provided similar N-glycosylation patterns. In fact, except for the absence of Sf-rhabdovirus, the only difference between Sf-RVN and Sf9 cells was SF-RVN produced higher levels of infectious baculovirus progeny. These results show Sf-RVN cells can be used as improved, alternative hosts to circumvent the potential safety hazard associated with the use of Sf-rhabdovirus-contaminated Sf cells for recombinant protein manufacturing with the BICS. Copyright © 2016 Elsevier Inc. All rights reserved.

Mycobacterium tuberculosis controls microRNA-99b (miR-99b) expression in infected murine dendritic cells to modulate host immunity.

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Singh, Yogesh; Kaul, Vandana; Mehra, Alka; Chatterjee, Samit; Tousif, Sultan; Dwivedi, Ved Prakash; Suar, Mrutyunjay; Van Kaer, Luc; Bishai, William R; Das, Gobardhan

2013-02-15

Mycobacterium tuberculosis resides and replicates within host phagocytes by modulating host microbicidal responses. In addition, it suppresses the production of host protective cytokines to prevent activation of and antigen presentation by M. tuberculosis-infected cells, causing dysregulation of host protective adaptive immune responses. Many cytokines are regulated by microRNAs (miRNAs), a newly discovered class of small noncoding RNAs, which have been implicated in modulating host immune responses in many bacterial and viral diseases. Here, we show that miRNA-99b (miR-99b), an orphan miRNA, plays a key role in the pathogenesis of M. tuberculosis infection. We found that miR-99b expression was highly up-regulated in M. tuberculosis strain H37Rv-infected dendritic cells (DCs) and macrophages. Blockade of miR-99b expression by antagomirs resulted in significantly reduced bacterial growth in DCs. Interestingly, knockdown of miR-99b in DCs significantly up-regulated proinflammatory cytokines such as IL-6, IL-12, and IL-1β. Furthermore, mRNA and membrane-bound protein data indicated that inhibition of miR-99b augments TNF-α and TNFRSF-4 production. Thus, miR-99b targets TNF-α and TNFRSF-4 receptor genes. Treatment of anti-miR-99b-transfected DCs with anti-TNF-α antibody resulted in increased bacterial burden. Thus, our findings unveil a novel host evasion mechanism adopted by M. tuberculosis via miR-99b, which may open up new avenues for designing miRNA-based vaccines and therapies.

Mycobacterium tuberculosis Controls MicroRNA-99b (miR-99b) Expression in Infected Murine Dendritic Cells to Modulate Host Immunity*

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Singh, Yogesh; Kaul, Vandana; Mehra, Alka; Chatterjee, Samit; Tousif, Sultan; Dwivedi, Ved Prakash; Suar, Mrutyunjay; Van Kaer, Luc; Bishai, William R.; Das, Gobardhan

2013-01-01

Mycobacterium tuberculosis resides and replicates within host phagocytes by modulating host microbicidal responses. In addition, it suppresses the production of host protective cytokines to prevent activation of and antigen presentation by M. tuberculosis-infected cells, causing dysregulation of host protective adaptive immune responses. Many cytokines are regulated by microRNAs (miRNAs), a newly discovered class of small noncoding RNAs, which have been implicated in modulating host immune responses in many bacterial and viral diseases. Here, we show that miRNA-99b (miR-99b), an orphan miRNA, plays a key role in the pathogenesis of M. tuberculosis infection. We found that miR-99b expression was highly up-regulated in M. tuberculosis strain H37Rv-infected dendritic cells (DCs) and macrophages. Blockade of miR-99b expression by antagomirs resulted in significantly reduced bacterial growth in DCs. Interestingly, knockdown of miR-99b in DCs significantly up-regulated proinflammatory cytokines such as IL-6, IL-12, and IL-1β. Furthermore, mRNA and membrane-bound protein data indicated that inhibition of miR-99b augments TNF-α and TNFRSF-4 production. Thus, miR-99b targets TNF-α and TNFRSF-4 receptor genes. Treatment of anti-miR-99b-transfected DCs with anti-TNF-α antibody resulted in increased bacterial burden. Thus, our findings unveil a novel host evasion mechanism adopted by M. tuberculosis via miR-99b, which may open up new avenues for designing miRNA-based vaccines and therapies. PMID:23233675

Experimental Andes virus infection in deer mice: characteristics of infection and clearance in a heterologous rodent host.

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Jessica R Spengler

Full Text Available New World hantaviruses can cause hantavirus cardiopulmonary syndrome with high mortality in humans. Distinct virus species are hosted by specific rodent reservoirs, which also serve as the vectors. Although regional spillover has been documented, it is unknown whether rodent reservoirs are competent for infection by hantaviruses that are geographically separated, and known to have related, but distinct rodent reservoir hosts. We show that Andes virus (ANDV of South America, carried by the long tailed pygmy rice rat (Oligoryzomys longicaudatus, infects and replicates in vitro and in vivo in the deer mouse (Peromyscus maniculatus, the reservoir host of Sin Nombre virus (SNV, found in North America. In experimentally infected deer mice, viral RNA was detected in the blood, lung, heart and spleen, but virus was cleared by 56 days post inoculation (dpi. All of the inoculated deer mice mounted a humoral immune response by 14 dpi, and produced measurable amounts of neutralizing antibodies by 21 dpi. An up-regulation of Ccl3, Ccl4, Ccl5, and Tgfb, a strong CD4⁺ T-cell response, and down-regulation of Il17, Il21 and Il23 occurred during infection. Infection was transient with an absence of clinical signs or histopathological changes. This is the first evidence that ANDV asymptomatically infects, and is immunogenic in deer mice, a non-natural host species of ANDV. Comparing the immune response in this model to that of the immune response in the natural hosts upon infection with their co-adapted hantaviruses may help clarify the mechanisms governing persistent infection in the natural hosts of hantaviruses.

Canine vector-borne co-infections: Ehrlichia canis and Hepatozoon canis in the same host monocytes.

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Baneth, Gad; Harrus, Shimon; Gal, Arnon; Aroch, Itamar

2015-02-28

The protozoon Hepatozoon canis and the rickettsia Ehrlichia canis are tick-borne pathogens, transmitted by Rhipicephalus sanguineus, which cause canine hepatozoonosis and canine monocytic ehrlichiosis, respectively. Co-infection of the same host monocytes with H. canis and E. canis confirmed by molecular characterization of the infecting agents and quantitative assessment of co-infected cells is described for the first time in three naturally-infected dogs. Blood smear evaluation indicated that at least 50% of the leukocytes infected with H. canis gamonts contained E. canis morulae. Co-infection of the same host cell demonstrated in this report suggests that infection with one pathogen may permit or enhance invasion or prolonged cellular survival of the other. Copyright © 2014 Elsevier B.V. All rights reserved.

Peptide Nucleic Acid Knockdown and Intra-host Cell Complementation of Ehrlichia Type IV Secretion System Effector

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Pratibha Sharma

2017-06-01

Full Text Available Survival of Ehrlichia chaffeensis depends on obligatory intracellular infection. One of the barriers to E. chaffeensis research progress has been the inability, using conventional techniques, to generate knock-out mutants for genes essential for intracellular infection. This study examined the use of Peptide Nucleic Acids (PNAs technology to interrupt type IV secretion system (T4SS effector protein expression in E. chaffeensis followed by intracellular complementation of the effector to determine its requirement for infection. Successful E. chaffeensis infection depends on the E. chaffeensis-specific T4SS protein effector, ehrlichial translocated factor-1 (Etf-1, which induces Rab5-regulated autophagy to provide host cytosolic nutrients required for E. chaffeensis proliferation. Etf-1 is also imported by host cell mitochondria where it inhibits host cell apoptosis to prolong its infection. We designed a PNA specific to Etf-1 and showed that the PNA bound to the target region of single-stranded Etf-1 RNA using a competitive binding assay. Electroporation of E. chaffeensis with this PNA significantly reduced Etf-1 mRNA and protein, and the bacteria's ability to induce host cell autophagy and infect host cells. Etf-1 PNA-mediated inhibition of ehrlichial Etf-1 expression and E. chaffeensis infection could be intracellularly trans-complemented by ectopic expression of Etf-1-GFP in host cells. These data affirmed the critical role of bacterial T4SS effector in host cell autophagy and E. chaffeensis infection, and demonstrated the use of PNA to analyze the gene functions of obligate intracellular bacteria.

Proteome profile of swine testicular cells infected with porcine transmissible gastroenteritis coronavirus.

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Ruili Ma

Full Text Available The interactions occurring between a virus and a host cell during a viral infection are complex. The purpose of this paper was to analyze altered cellular protein levels in porcine transmissible gastroenteritis coronavirus (TGEV-infected swine testicular (ST cells in order to determine potential virus-host interactions. A proteomic approach using isobaric tags for relative and absolute quantitation (iTRAQ-coupled two-dimensional liquid chromatography-tandem mass spectrometry identification was conducted on the TGEV-infected ST cells. The results showed that the 4-plex iTRAQ-based quantitative approach identified 4,112 proteins, 146 of which showed significant changes in expression 48 h after infection. At 64 h post infection, 219 of these proteins showed significant change, further indicating that a larger number of proteomic changes appear to occur during the later stages of infection. Gene ontology analysis of the altered proteins showed enrichment in multiple biological processes, including cell adhesion, response to stress, generation of precursor metabolites and energy, cell motility, protein complex assembly, growth, developmental maturation, immune system process, extracellular matrix organization, locomotion, cell-cell signaling, neurological system process, and cell junction organization. Changes in the expression levels of transforming growth factor beta 1 (TGF-β1, caspase-8, and heat shock protein 90 alpha (HSP90α were also verified by western blot analysis. To our knowledge, this study is the first time the response profile of ST host cells following TGEV infection has been analyzed using iTRAQ technology, and our description of the late proteomic changes that are occurring after the time of vigorous viral production are novel. Therefore, this study provides a solid foundation for further investigation, and will likely help us to better understand the mechanisms of TGEV infection and pathogenesis.

Perturbation of host-cell membrane is a primary mechanism of HIV cytopathology.

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Cloyd, M W; Lynn, W S

1991-04-01

Cytopathic viruses injure cells by a number of different mechanisms. The mechanism by which HIV-1 injures T cells was studied by temporally examining host-cell macromolecular syntheses, stages of the cell cycle, and membrane permeability following acute infection. T cells cytopathically infected at an m.o.i. of 1-5 grew normally for 24-72 hr, depending on the cell line, followed by the first manifestation of cell injury, slowing of cell division. At that time significant amounts of unintegrated HIV DNA and p24 core protein became detectable, and acridine orange flow cytometric cell cycle studies demonstrated the presence of fewer cells in the G2/M stage of the cell cycle. There was no change in the frequency of cells in the S-stage, and metabolic pulsing with radioactive precursors demonstrated that host-cell DNA, RNA, and protein syntheses were normal at that time and normal up to the time cells started to die (approximately 24 hr later), when all three decreased. Cellular lipid synthesis, however, was perturbed when cell multiplication slowed, with phospholipid synthesis reduced and neutral lipid synthesis enhanced. Permeability of the host-cell membrane to small molecules, such as Ca2+ and sucrose, was slightly enhanced early postinfection, and by the time of slowing of cell division, host membrane permeability was greatly increased to both Ca2+ and sucrose (Stokes radius 5.2 A) but not to inulin (Stokes radium 20 A). These changes in host-cell membrane permeability and phospholipid synthesis were not observed in acutely infected H9 cells, which are not susceptible to HIV cytopathology. Thus, HIV-1 appeared to predominantly injure T cells by perturbing host-cell membrane permeability and lipid synthesis, which is similar to the cytopathic mechanisms of paramyxoviruses.

Mycobacterium tuberculosis nuoG is a virulence gene that inhibits apoptosis of infected host cells.

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Kamalakannan Velmurugan

2007-07-01

Full Text Available The survival and persistence of Mycobacterium tuberculosis depends on its capacity to manipulate multiple host defense pathways, including the ability to actively inhibit the death by apoptosis of infected host cells. The genetic basis for this anti-apoptotic activity and its implication for mycobacterial virulence have not been demonstrated or elucidated. Using a novel gain-of-function genetic screen, we demonstrated that inhibition of infection-induced apoptosis of macrophages is controlled by multiple genetic loci in M. tuberculosis. Characterization of one of these loci in detail revealed that the anti-apoptosis activity was attributable to the type I NADH-dehydrogenase of M. tuberculosis, and was mainly due to the subunit of this multicomponent complex encoded by the nuoG gene. Expression of M. tuberculosis nuoG in nonpathogenic mycobacteria endowed them with the ability to inhibit apoptosis of infected human or mouse macrophages, and increased their virulence in a SCID mouse model. Conversely, deletion of nuoG in M. tuberculosis ablated its ability to inhibit macrophage apoptosis and significantly reduced its virulence in mice. These results identify a key component of the genetic basis for an important virulence trait of M. tuberculosis and support a direct causal relationship between virulence of pathogenic mycobacteria and their ability to inhibit macrophage apoptosis.

Host control of human papillomavirus infection and disease.

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Doorbar, John

2018-02-01

Most human papillomaviruses cause inapparent infections, subtly affecting epithelial homeostasis, to ensure genome persistence in the epithelial basal layer. As with conspicuous papillomas, these self-limiting lesions shed viral particles to ensure population level maintenance and depend on a balance between viral gene expression, immune cell stimulation and immune surveillance for persistence. The complex immune evasion strategies, characteristic of high-risk HPV types, also allow the deregulated viral gene expression that underlies neoplasia. Neoplasia occurs at particular epithelial sites where vulnerable cells such as the reserve or cuboidal cells of the cervical transformation zone are found. Beta papillomavirus infection can also predispose an individual with immune deficiencies to the development of cancers. The host control of HPV infections thus involves local interactions between keratinocytes and the adaptive immune response. Effective immune detection and surveillance limits overt disease, leading to HPV persistence as productive microlesions or in a true latent state. Copyright © 2017. Published by Elsevier Ltd.

The structural proteins of epidemic and historical strains of Zika virus differ in their ability to initiate viral infection in human host cells.

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Bos, Sandra; Viranaicken, Wildriss; Turpin, Jonathan; El-Kalamouni, Chaker; Roche, Marjolaine; Krejbich-Trotot, Pascale; Desprès, Philippe; Gadea, Gilles

2018-03-01

Mosquito-borne Zika virus (ZIKV) recently emerged in South Pacific islands and Americas where large epidemics were documented. In the present study, we investigated the contribution of the structural proteins C, prM and E in the permissiveness of human host cells to epidemic strains of ZIKV. To this end, we evaluated the capacity of the epidemic strain BeH819015 to infect epithelial A549 and neuronal SH-SY5Y cells in comparison to the African historical MR766 strain. For that purpose, we generated a molecular clone of BeH819015 and a chimeric clone of MR766 which contains the BeH819015 structural protein region. We showed that ZIKV containing BeH819015 structural proteins was much less efficient in cell-attachment leading to a reduced susceptibility of A549 and SH-SY5Y cells to viral infection. Our data illustrate a previously underrated role for C, prM, and E in ZIKV epidemic strain ability to initiate viral infection in human host cells. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

The homeostasis of Plasmodium falciparum-infected red blood cells.

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Jakob M A Mauritz

2009-04-01

Full Text Available The asexual reproduction cycle of Plasmodium falciparum, the parasite responsible for severe malaria, occurs within red blood cells. A merozoite invades a red cell in the circulation, develops and multiplies, and after about 48 hours ruptures the host cell, releasing 15-32 merozoites ready to invade new red blood cells. During this cycle, the parasite increases the host cell permeability so much that when similar permeabilization was simulated on uninfected red cells, lysis occurred before approximately 48 h. So how could infected cells, with a growing parasite inside, prevent lysis before the parasite has completed its developmental cycle? A mathematical model of the homeostasis of infected red cells suggested that it is the wasteful consumption of host cell hemoglobin that prevents early lysis by the progressive reduction in the colloid-osmotic pressure within the host (the colloid-osmotic hypothesis. However, two critical model predictions, that infected cells would swell to near prelytic sphericity and that the hemoglobin concentration would become progressively reduced, remained controversial. In this paper, we are able for the first time to correlate model predictions with recent experimental data in the literature and explore the fine details of the homeostasis of infected red blood cells during five model-defined periods of parasite development. The conclusions suggest that infected red cells do reach proximity to lytic rupture regardless of their actual volume, thus requiring a progressive reduction in their hemoglobin concentration to prevent premature lysis.

Human subtilase SKI-1/S1P is a master regulator of the HCV Lifecycle and a potential host cell target for developing indirect-acting antiviral agents.

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Andrea D Olmstead

2012-01-01

Full Text Available HCV infection is a major risk factor for liver cancer and liver transplantation worldwide. Overstimulation of host lipid metabolism in the liver by HCV-encoded proteins during viral infection creates a favorable environment for virus propagation and pathogenesis. In this study, we hypothesize that targeting cellular enzymes acting as master regulators of lipid homeostasis could represent a powerful approach to developing a novel class of broad-spectrum antivirals against infection associated with human Flaviviridae viruses such as hepatitis C virus (HCV, whose assembly and pathogenesis depend on interaction with lipid droplets (LDs. One such master regulator of cholesterol metabolic pathways is the host subtilisin/kexin-isozyme-1 (SKI-1--or site-1 protease (S1P. SKI-1/S1P plays a critical role in the proteolytic activation of sterol regulatory element binding proteins (SREBPs, which control expression of the key enzymes of cholesterol and fatty-acid biosynthesis. Here we report the development of a SKI-1/S1P-specific protein-based inhibitor and its application to blocking the SREBP signaling cascade. We demonstrate that SKI-1/S1P inhibition effectively blocks HCV from establishing infection in hepatoma cells. The inhibitory mechanism is associated with a dramatic reduction in the abundance of neutral lipids, LDs, and the LD marker: adipose differentiation-related protein (ADRP/perilipin 2. Reduction of LD formation inhibits virus assembly from infected cells. Importantly, we confirm that SKI-1/S1P is a key host factor for HCV infection by using a specific active, site-directed, small-molecule inhibitor of SKI-1/S1P: PF-429242. Our studies identify SKI-1/S1P as both a novel regulator of the HCV lifecycle and as a potential host-directed therapeutic target against HCV infection and liver steatosis. With identification of an increasing number of human viruses that use host LDs for infection, our results suggest that SKI-1/S1P inhibitors may allow

Insights into Host Cell Modulation and Induction of New Cells by the Corn Smut Ustilago maydis

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Amey Redkar

2017-05-01

Full Text Available Many filamentous fungal pathogens induce drastic modulation of host cells causing abnormal infectious structures such as galls, or tumors that arise as a result of re-programming in the original developmental cell fate of a colonized host cell. Developmental consequences occur predominantly with biotrophic phytopathogens. This suggests that these host structures result as an outcome of efficient defense suppression and intimate fungal–host interaction to suit the pathogen’s needs for completion of its infection cycle. This mini-review mainly summarizes host cell re-programming that occurs in the Ustilago maydis – maize interaction, in which the pathogen deploys cell-type specific effector proteins with varying activities. The fungus senses the physiological status and identity of colonized host cells and re-directs the endogenous developmental program of its host. The disturbance of host cell physiology and cell fate leads to novel cell shapes, increased cell size, and/or the number of host cells. We particularly highlight the strategies of U. maydis to induce physiologically varied host organs to form the characteristic tumors in both vegetative and floral parts of maize.

Approach to skin and soft tissue infections in non-HIV immunocompromised hosts.

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Burke, Victoria E; Lopez, Fred A

2017-08-01

Skin and soft tissue infections are frequent contributors to morbidity and mortality in the immunocompromised host. This article reviews the changing epidemiology and clinical manifestations of the most common cutaneous pathogens in non-HIV immunocompromised hosts, including patients with solid organ transplants, stem cell transplants, solid tumors, hematologic malignancies, and receiving chronic immunosuppressive therapy for inflammatory disorders. Defects in the innate or adaptive immune response can predispose the immunocompromised host to certain cutaneous infections in a predictive fashion. Cutaneous lesions in patients with neutrophil defects are commonly due to bacteria, Candida, or invasive molds. Skin lesions in patients with cellular or humoral immunodeficiencies can be due to encapsulated bacteria, Nocardia, mycobacteria, endemic fungal infections, herpesviruses, or parasites. Skin lesions may reflect primary inoculation or, more commonly, disseminated infection. Tissue samples for microscopy, culture, and histopathology are critical to making an accurate diagnosis given the nonspecific and heterogeneous appearance of these skin lesions due to a blunted immune response. As the population of non-HIV immunosuppressed hosts expands with advances in medical therapies, the frequency and variety of cutaneous diseases in these hosts will increase.

Temporal dynamics of host molecular responses differentiate symptomatic and asymptomatic influenza a infection.

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Yongsheng Huang

2011-08-01

Full Text Available Exposure to influenza viruses is necessary, but not sufficient, for healthy human hosts to develop symptomatic illness. The host response is an important determinant of disease progression. In order to delineate host molecular responses that differentiate symptomatic and asymptomatic Influenza A infection, we inoculated 17 healthy adults with live influenza (H3N2/Wisconsin and examined changes in host peripheral blood gene expression at 16 timepoints over 132 hours. Here we present distinct transcriptional dynamics of host responses unique to asymptomatic and symptomatic infections. We show that symptomatic hosts invoke, simultaneously, multiple pattern recognition receptors-mediated antiviral and inflammatory responses that may relate to virus-induced oxidative stress. In contrast, asymptomatic subjects tightly regulate these responses and exhibit elevated expression of genes that function in antioxidant responses and cell-mediated responses. We reveal an ab initio molecular signature that strongly correlates to symptomatic clinical disease and biomarkers whose expression patterns best discriminate early from late phases of infection. Our results establish a temporal pattern of host molecular responses that differentiates symptomatic from asymptomatic infections and reveals an asymptomatic host-unique non-passive response signature, suggesting novel putative molecular targets for both prognostic assessment and ameliorative therapeutic intervention in seasonal and pandemic influenza.

Detection of PR-39, a porcine host defence peptide, in different cell sub-linages in pigs infected with Actinobacillus pleuropneumoniae.

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Gabner, S; Egerbacher, M; Gasse, H; Hewicker-Trautwein, M; Höltig, D; Waldmann, K-H; Blecha, F; Saalmüller, A; Hennig-Pauka, I

2017-10-01

Innate immunity is critically important for the outcome of infection in many diseases. It was previously shown that cathelicidin PR-39, an important porcine multifunctional host defence peptide, is elevated in bronchoalveolar lavage fluid and respiratory tract tissue after experimental infection with Actinobacillus pleuropneumoniae (A.pp.). To date, neutrophil polymorphonuclear leukocytes (PMNs) are thought to be the only source of PR-39. The aim of this study was to further characterize PR-39⁺ cells and selected immune cell populations in lung tissue during the peracute (7-10 hours), acute (2 days), reconvalescent (7 days) and chronic (21 days) stages of experimental infection with A.pp. serotype 2. In total, six mock-infected control pigs and 12 infected pigs were examined. Using immunofluorescence double-labeling, antibodies against PR-39 were combined with antibodies against CD3 (T-cells), CD79 (B-cells), Iba1 (activated macrophages), TTF-1 (lung epithelial cells expressing surfactant proteins), macrophage/L1 protein and myeloperoxidase (MPO, cells of the myeloid linage). In the peracute and acute phases of infection, total PR-39⁺ cells and myeloid linage cells increased, whereas CD3⁺ cells and TTF-1⁺ cells decreased. Double labeling revealed that most Macrophage/L1 protein+ cells and to a lesser extent MPO⁺ cells co-expressed PR-39. In addition, few bronchial epithelial cells and type 2 alveolar epithelial cells (both identified with TTF-1) produced PR-39. Occasionally, CD3⁺ T cells expressing PR-39 were seen in infected animals. Taken together, this study identifies cell types, other than PMNs, in lungs of A.pp.-infected pigs that are capable of producing PR-39. In addition, these findings provide further insights into the dynamics of different immune cell populations during A.pp.-infection.

Structural Basis of the Interaction of a Trypanosoma cruzi Surface Molecule Implicated in Oral Infection with Host Cells and Gastric Mucin

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Cortez, Cristian; Yoshida, Nobuko; Bahia, Diana; Sobreira, Tiago J.P.

2012-01-01

Host cell invasion and dissemination within the host are hallmarks of virulence for many pathogenic microorganisms. As concerns Trypanosoma cruzi, which causes Chagas disease, the insect vector-derived metacyclic trypomastigotes (MT) initiate infection by invading host cells, and later blood trypomastigotes disseminate to diverse organs and tissues. Studies with MT generated in vitro and tissue culture-derived trypomastigotes (TCT), as counterparts of insect-borne and bloodstream parasites, have implicated members of the gp85/trans-sialidase superfamily, MT gp82 and TCT Tc85-11, in cell invasion and interaction with host factors. Here we analyzed the gp82 structure/function characteristics and compared them with those previously reported for Tc85-11. One of the gp82 sequences identified as a cell binding site consisted of an α-helix, which connects the N-terminal β-propeller domain to the C-terminal β-sandwich domain where the second binding site is nested. In the gp82 structure model, both sites were exposed at the surface. Unlike gp82, the Tc85-11 cell adhesion sites are located in the N-terminal β-propeller region. The gp82 sequence corresponding to the epitope for a monoclonal antibody that inhibits MT entry into target cells was exposed on the surface, upstream and contiguous to the α-helix. Located downstream and close to the α-helix was the gp82 gastric mucin binding site, which plays a central role in oral T. cruzi infection. The sequences equivalent to Tc85-11 laminin-binding sites, which have been associated with the parasite ability to overcome extracellular matrices and basal laminae, was poorly conserved in gp82, compatible with its reduced capacity to bind laminin. Our study indicates that gp82 is structurally suited for MT to initiate infection by the oral route, whereas Tc85-11, with its affinity for laminin, would facilitate the parasite dissemination through diverse organs and tissues. PMID:22860068

How pathogens use linear motifs to perturb host cell networks

KAUST Repository

Via, Allegra; Uyar, Bora; Brun, Christine; Zanzoni, Andreas

2015-01-01

Molecular mimicry is one of the powerful stratagems that pathogens employ to colonise their hosts and take advantage of host cell functions to guarantee their replication and dissemination. In particular, several viruses have evolved the ability to interact with host cell components through protein short linear motifs (SLiMs) that mimic host SLiMs, thus facilitating their internalisation and the manipulation of a wide range of cellular networks. Here we present convincing evidence from the literature that motif mimicry also represents an effective, widespread hijacking strategy in prokaryotic and eukaryotic parasites. Further insights into host motif mimicry would be of great help in the elucidation of the molecular mechanisms behind host cell invasion and the development of anti-infective therapeutic strategies.

Host gene expression profiles in ferrets infected with genetically distinct henipavirus strains.

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Alberto J Leon

2018-03-01

Full Text Available Henipavirus infection causes severe respiratory and neurological disease in humans that can be fatal. To characterize the pathogenic mechanisms of henipavirus infection in vivo, we performed experimental infections in ferrets followed by genome-wide gene expression analysis of lung and brain tissues. The Hendra, Nipah-Bangladesh, and Nipah-Malaysia strains caused severe respiratory and neurological disease with animals succumbing around 7 days post infection. Despite the presence of abundant viral shedding, animal-to-animal transmission did not occur. The host gene expression profiles of the lung tissue showed early activation of interferon responses and subsequent expression of inflammation-related genes that coincided with the clinical deterioration. Additionally, the lung tissue showed unchanged levels of lymphocyte markers and progressive downregulation of cell cycle genes and extracellular matrix components. Infection in the brain resulted in a limited breadth of the host responses, which is in accordance with the immunoprivileged status of this organ. Finally, we propose a model of the pathogenic mechanisms of henipavirus infection that integrates multiple components of the host responses.

A T4SS Effector Targets Host Cell Alpha-Enolase Contributing to Brucella abortus Intracellular Lifestyle.

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Marchesini, María I; Morrone Seijo, Susana M; Guaimas, Francisco F; Comerci, Diego J

2016-01-01

Brucella abortus , the causative agent of bovine brucellosis, invades and replicates within cells inside a membrane-bound compartment known as the Brucella containing vacuole (BCV). After trafficking along the endocytic and secretory pathways, BCVs mature into endoplasmic reticulum-derived compartments permissive for bacterial replication. Brucella Type IV Secretion System (VirB) is a major virulence factor essential for the biogenesis of the replicative organelle. Upon infection, Brucella uses the VirB system to translocate effector proteins from the BCV into the host cell cytoplasm. Although the functions of many translocated proteins remain unknown, some of them have been demonstrated to modulate host cell signaling pathways to favor intracellular survival and replication. BPE123 (BAB2_0123) is a B. abortus VirB-translocated effector protein recently identified by our group whose function is yet unknown. In an attempt to identify host cell proteins interacting with BPE123, a pull-down assay was performed and human alpha-enolase (ENO-1) was identified by LC/MS-MS as a potential interaction partner of BPE123. These results were confirmed by immunoprecipitation assays. In bone-marrow derived macrophages infected with B. abortus , ENO-1 associates to BCVs in a BPE123-dependent manner, indicating that interaction with translocated BPE123 is also occurring during the intracellular phase of the bacterium. Furthermore, ENO-1 depletion by siRNA impaired B. abortus intracellular replication in HeLa cells, confirming a role for α-enolase during the infection process. Indeed, ENO-1 activity levels were enhanced upon B. abortus infection of THP-1 macrophagic cells, and this activation is highly dependent on BPE123. Taken together, these results suggest that interaction between BPE123 and host cell ENO-1 contributes to the intracellular lifestyle of B. abortus .

Comparative Proteomics Identifies Host Immune System Proteins Affected by Infection with Mycobacterium bovis.

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Vladimir López

2016-03-01

Full Text Available Mycobacteria of the Mycobacterium tuberculosis complex (MTBC greatly impact human and animal health worldwide. The mycobacterial life cycle is complex, and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Eurasian wild boar (Sus scrofa are natural reservoir hosts for MTBC and a model for mycobacterial infection and tuberculosis (TB. In the wild boar TB model, mycobacterial infection affects the expression of innate and adaptive immune response genes in mandibular lymph nodes and oropharyngeal tonsils, and biomarkers have been proposed as correlates with resistance to natural infection. However, the mechanisms used by mycobacteria to manipulate host immune response are not fully characterized. Our hypothesis is that the immune system proteins under-represented in infected animals, when compared to uninfected controls, are used by mycobacteria to guarantee pathogen infection and transmission. To address this hypothesis, a comparative proteomics approach was used to compare host response between uninfected (TB- and M. bovis-infected young (TB+ and adult animals with different infection status [TB lesions localized in the head (TB+ or affecting multiple organs (TB++]. The results identified host immune system proteins that play an important role in host response to mycobacteria. Calcium binding protein A9, Heme peroxidase, Lactotransferrin, Cathelicidin and Peptidoglycan-recognition protein were under-represented in TB+ animals when compared to uninfected TB- controls, but protein levels were higher as infection progressed in TB++ animals when compared to TB- and/or TB+ adult wild boar. MHCI was the only protein over-represented in TB+ adult wild boar when compared to uninfected TB- controls. The results reported here suggest that M. bovis manipulates host immune response by reducing the production of immune system proteins. However, as infection progresses, wild boar immune response recovers to

Comparative Proteomics Identifies Host Immune System Proteins Affected by Infection with Mycobacterium bovis.

Science.gov (United States)

López, Vladimir; Villar, Margarita; Queirós, João; Vicente, Joaquín; Mateos-Hernández, Lourdes; Díez-Delgado, Iratxe; Contreras, Marinela; Alves, Paulo C; Alberdi, Pilar; Gortázar, Christian; de la Fuente, José

2016-03-01

Mycobacteria of the Mycobacterium tuberculosis complex (MTBC) greatly impact human and animal health worldwide. The mycobacterial life cycle is complex, and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Eurasian wild boar (Sus scrofa) are natural reservoir hosts for MTBC and a model for mycobacterial infection and tuberculosis (TB). In the wild boar TB model, mycobacterial infection affects the expression of innate and adaptive immune response genes in mandibular lymph nodes and oropharyngeal tonsils, and biomarkers have been proposed as correlates with resistance to natural infection. However, the mechanisms used by mycobacteria to manipulate host immune response are not fully characterized. Our hypothesis is that the immune system proteins under-represented in infected animals, when compared to uninfected controls, are used by mycobacteria to guarantee pathogen infection and transmission. To address this hypothesis, a comparative proteomics approach was used to compare host response between uninfected (TB-) and M. bovis-infected young (TB+) and adult animals with different infection status [TB lesions localized in the head (TB+) or affecting multiple organs (TB++)]. The results identified host immune system proteins that play an important role in host response to mycobacteria. Calcium binding protein A9, Heme peroxidase, Lactotransferrin, Cathelicidin and Peptidoglycan-recognition protein were under-represented in TB+ animals when compared to uninfected TB- controls, but protein levels were higher as infection progressed in TB++ animals when compared to TB- and/or TB+ adult wild boar. MHCI was the only protein over-represented in TB+ adult wild boar when compared to uninfected TB- controls. The results reported here suggest that M. bovis manipulates host immune response by reducing the production of immune system proteins. However, as infection progresses, wild boar immune response recovers to limit pathogen

Parasitic infection improves survival from septic peritonitis by enhancing mast cell responses to bacteria in mice.

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Rachel E Sutherland

Full Text Available Mammals are serially infected with a variety of microorganisms, including bacteria and parasites. Each infection reprograms the immune system's responses to re-exposure and potentially alters responses to first-time infection by different microorganisms. To examine whether infection with a metazoan parasite modulates host responses to subsequent bacterial infection, mice were infected with the hookworm-like intestinal nematode Nippostrongylus brasiliensis, followed in 2-4 weeks by peritoneal injection of the pathogenic bacterium Klebsiella pneumoniae. Survival from Klebsiella peritonitis two weeks after parasite infection was better in Nippostrongylus-infected animals than in unparasitized mice, with Nippostrongylus-infected mice having fewer peritoneal bacteria, more neutrophils, and higher levels of protective interleukin 6. The improved survival of Nippostrongylus-infected mice depends on IL-4 because the survival benefit is lost in mice lacking IL-4. Because mast cells protect mice from Klebsiella peritonitis, we examined responses in mast cell-deficient Kit(W-sh/Kit(W-sh mice, in which parasitosis failed to improve survival from Klebsiella peritonitis. However, adoptive transfer of cultured mast cells to Kit(W-sh/Kit(W-sh mice restored survival benefits of parasitosis. These results show that recent infection with Nippostrongylus brasiliensis protects mice from Klebsiella peritonitis by modulating mast cell contributions to host defense, and suggest more generally that parasitosis can yield survival advantages to a bacterially infected host.

Host age modulates parasite infectivity, virulence and reproduction.

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Izhar, Rony; Ben-Ami, Frida

2015-07-01

Host age is one of the most striking differences among hosts within most populations, but there is very little data on how age-dependent effects impact ecological and evolutionary dynamics of both the host and the parasite. Here, we examined the influence of host age (juveniles, young and old adults) at parasite exposure on host susceptibility, fecundity and survival as well as parasite transmission, using two clones of the water flea Daphnia magna and two clones of its bacterial parasite Pasteuria ramosa. Younger D. magna were more susceptible to infection than older ones, regardless of host or parasite clone. Also, younger-infected D. magna became castrated faster than older hosts, but host and parasite clone effects contributed to this trait as well. Furthermore, the early-infected D. magna produced considerably more parasite transmission stages than late-infected ones, while host age at exposure did not affect virulence as it is defined in models (host mortality). When virulence is defined more broadly as the negative effects of infection on host fitness, by integrating the parasitic effects on host fecundity and mortality, then host age at exposure seems to slide along a negative relationship between host and parasite fitness. Thus, the virulence-transmission trade-off differs strongly among age classes, which in turn affects predictions of optimal virulence. Age-dependent effects on host susceptibility, virulence and parasite transmission could pose an important challenge for experimental and theoretical studies of infectious disease dynamics and disease ecology. Our results present a call for a more explicit stage-structured theory for disease, which will incorporate age-dependent epidemiological parameters. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

Efferocytosis of Pathogen-Infected Cells

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Niloofar Karaji

2017-12-01

Full Text Available The prompt and efficient clearance of unwanted and abnormal cells by phagocytes is termed efferocytosis and is crucial for organism development, maintenance of tissue homeostasis, and regulation of the immune system. Dying cells are recognized by phagocytes through pathways initiated via “find me” signals, recognition via “eat me” signals and down-modulation of regulatory “don’t eat me” signals. Pathogen infection may trigger cell death that drives phagocytic clearance in an immunologically silent, or pro-inflammatory manner, depending on the mode of cell death. In many cases, efferocytosis is a mechanism for eliminating pathogens and pathogen-infected cells; however, some pathogens have subverted this process and use efferocytic mechanisms to avoid innate immune detection and assist phagocyte infection. In parallel, phagocytes can integrate signals received from infected dying cells to elicit the most appropriate effector response against the infecting pathogen. This review focuses on pathogen-induced cell death signals that drive infected cell recognition and uptake by phagocytes, and the outcomes for the infected target cell, the phagocyte, the pathogen and the host.

Viral and Host Factors Required for Avian H5N1 Influenza A Virus Replication in Mammalian Cells

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Hong Zhang

2013-06-01

Full Text Available Following the initial and sporadic emergence into humans of highly pathogenic avian H5N1 influenza A viruses in Hong Kong in 1997, we have come to realize the potential for avian influenza A viruses to be transmitted directly from birds to humans. Understanding the basic viral and cellular mechanisms that contribute to infection of mammalian species with avian influenza viruses is essential for developing prevention and control measures against possible future human pandemics. Multiple physical and functional cellular barriers can restrict influenza A virus infection in a new host species, including the cell membrane, the nuclear envelope, the nuclear environment, and innate antiviral responses. In this review, we summarize current knowledge on viral and host factors required for avian H5N1 influenza A viruses to successfully establish infections in mammalian cells. We focus on the molecular mechanisms underpinning mammalian host restrictions, as well as the adaptive mutations that are necessary for an avian influenza virus to overcome them. It is likely that many more viral and host determinants remain to be discovered, and future research in this area should provide novel and translational insights into the biology of influenza virus-host interactions.

Infection history of the blood-meal host dictates pathogenic potential of the Lyme disease spirochete within the feeding tick vector.

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Bharti Bhatia

2018-04-01

Full Text Available Lyme disease in humans is caused by several genospecies of the Borrelia burgdorferi sensu lato (s.l. complex of spirochetal bacteria, including B. burgdorferi, B. afzelii and B. garinii. These bacteria exist in nature as obligate parasites in an enzootic cycle between small vertebrate hosts and Ixodid tick vectors, with humans representing incidental hosts. During the natural enzootic cycle, infected ticks in endemic areas feed not only upon naïve hosts, but also upon seropositive infected hosts. In the current study, we considered this environmental parameter and assessed the impact of the immune status of the blood-meal host on the phenotype of the Lyme disease spirochete within the tick vector. We found that blood from a seropositive host profoundly attenuates the infectivity (>104 fold of homologous spirochetes within the tick vector without killing them. This dramatic neutralization of vector-borne spirochetes was not observed, however, when ticks and blood-meal hosts carried heterologous B. burgdorferi s.l. strains, or when mice lacking humoral immunity replaced wild-type mice as blood-meal hosts in similar experiments. Mechanistically, serum-mediated neutralization does not block induction of host-adapted OspC+ spirochetes during tick feeding, nor require tick midgut components. Significantly, this study demonstrates that strain-specific antibodies elicited by B. burgdorferi s.l. infection neutralize homologous bacteria within feeding ticks, before the Lyme disease spirochetes enter a host. The blood meal ingested from an infected host thereby prevents super-infection by homologous spirochetes, while facilitating transmission of heterologous B. burgdorferi s.l. strains. This finding suggests that Lyme disease spirochete diversity is stably maintained within endemic populations in local geographic regions through frequency-dependent selection of rare alleles of dominant polymorphic surface antigens.

The influenza fingerprints: NS1 and M1 proteins contribute to specific host cell ultrastructure signatures upon infection by different influenza A viruses

Energy Technology Data Exchange (ETDEWEB)

Terrier, Olivier; Moules, Vincent; Carron, Coralie; Cartet, Gaeelle [Equipe VirCell, Laboratoire de Virologie et Pathologie Humaine, VirPath EMR 4610, Universite de Lyon, Universite Claude Bernard Lyon 1, Hospices Civils de Lyon, Faculte de medecine RTH Laennec, rue Guillaume Paradin, F-69008 Lyon (France); Frobert, Emilie [Laboratoire de Virologie, Centre de Biologie et de Pathologie Est, Hospices Civils de Lyon, 59 boulevard Pinel, F-69677 Bron Cedex, Lyon (France); Yver, Matthieu; Traversier, Aurelien [Equipe VirCell, Laboratoire de Virologie et Pathologie Humaine, VirPath EMR 4610, Universite de Lyon, Universite Claude Bernard Lyon 1, Hospices Civils de Lyon, Faculte de medecine RTH Laennec, rue Guillaume Paradin, F-69008 Lyon (France); Wolff, Thorsten [Division of Influenza/Respiratory Viruses, Robert Koch Institute, Nordufer 20, D-13353 Berlin (Germany); Riteau, Beatrice [Laboratoire de Virologie et Pathologie Humaine, VirPath EMR 4610, Universite de Lyon, Universite Claude Bernard Lyon 1, Hospices Civils de Lyon, Faculte de medecine RTH Laennec, rue Guillaume Paradin, F-69008 Lyon (France); Naffakh, Nadia [Institut Pasteur, Unite de Genetique Moleculaire des Virus Respiratoires, URA CNRS 3015, EA302 Universite Paris Diderot, Paris (France); and others

2012-10-10

Influenza A are nuclear replicating viruses which hijack host machineries in order to achieve optimal infection. Numerous functional virus-host interactions have now been characterized, but little information has been gathered concerning their link to the virally induced remodeling of the host cellular architecture. In this study, we infected cells with several human and avian influenza viruses and we have analyzed their ultrastructural modifications by using electron and confocal microscopy. We discovered that infections lead to a major and systematic disruption of nucleoli and the formation of a large number of diverse viral structures showing specificity that depended on the subtype origin and genomic composition of viruses. We identified NS1 and M1 proteins as the main actors in the remodeling of the host ultra-structure and our results suggest that each influenza A virus strain could be associated with a specific cellular fingerprint, possibly correlated to the functional properties of their viral components.

The influenza fingerprints: NS1 and M1 proteins contribute to specific host cell ultrastructure signatures upon infection by different influenza A viruses

International Nuclear Information System (INIS)

Terrier, Olivier; Moules, Vincent; Carron, Coralie; Cartet, Gaëlle; Frobert, Emilie; Yver, Matthieu; Traversier, Aurelien; Wolff, Thorsten; Riteau, Beatrice; Naffakh, Nadia

2012-01-01

Influenza A are nuclear replicating viruses which hijack host machineries in order to achieve optimal infection. Numerous functional virus–host interactions have now been characterized, but little information has been gathered concerning their link to the virally induced remodeling of the host cellular architecture. In this study, we infected cells with several human and avian influenza viruses and we have analyzed their ultrastructural modifications by using electron and confocal microscopy. We discovered that infections lead to a major and systematic disruption of nucleoli and the formation of a large number of diverse viral structures showing specificity that depended on the subtype origin and genomic composition of viruses. We identified NS1 and M1 proteins as the main actors in the remodeling of the host ultra-structure and our results suggest that each influenza A virus strain could be associated with a specific cellular fingerprint, possibly correlated to the functional properties of their viral components.

Cytotoxic Vibrio T3SS1 Rewires Host Gene Expression to Subvert Cell Death Signaling and Activate Cell Survival Networks

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De Nisco, Nicole J.; Kanchwala, Mohammed; Li, Peng; Fernandez, Jessie; Xing, Chao; Orth, Kim

2017-01-01

Bacterial effectors are potent manipulators of host signaling pathways. The marine bacterium Vibrio parahaemolyticus (V. para), delivers effectors into host cells through two type three secretion systems (T3SS). The ubiquitous T3SS1 is vital for V. para survival in the environment, whereas T3SS2 causes acute gastroenteritis in human hosts. Although the natural host is undefined, T3SS1 effectors attack highly conserved cellular processes and pathways to orchestrate non-apoptotic cell death. Much is known about how T3SS1 effectors function in isolation, but we wanted to understand how their concerted action globally affects host cell signaling. To assess the host response to T3SS1, we compared gene expression changes over time in primary fibroblasts infected with V. para that have a functional T3SS1 (T3SS1+) to those in cells infected with V. para lacking T3SS1 (T3SS1−). Overall, the host transcriptional response to both T3SS1+ and T3SS1− V. para was rapid, robust, and temporally dynamic. T3SS1 re-wired host gene expression by specifically altering the expression of 398 genes. Although T3SS1 effectors target host cells at the posttranslational level to cause cytotoxicity, network analysis indicated that V. para T3SS1 also precipitates a host transcriptional response that initially activates cell survival and represses cell death networks. The increased expression of several key pro-survival transcripts mediated by T3SS1 was dependent on a host signaling pathway that is silenced later in infection by the posttranslational action of T3SS1. Taken together, our analysis reveals a complex interplay between roles of T3SS1 as both a transcriptional and posttranslational manipulator of host cell signaling. PMID:28512145

Mixed infections reveal virulence differences between host-specific bee pathogens.

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Klinger, Ellen G; Vojvodic, Svjetlana; DeGrandi-Hoffman, Gloria; Welker, Dennis L; James, Rosalind R

2015-07-01

Dynamics of host-pathogen interactions are complex, often influencing the ecology, evolution and behavior of both the host and pathogen. In the natural world, infections with multiple pathogens are common, yet due to their complexity, interactions can be difficult to predict and study. Mathematical models help facilitate our understanding of these evolutionary processes, but empirical data are needed to test model assumptions and predictions. We used two common theoretical models regarding mixed infections (superinfection and co-infection) to determine which model assumptions best described a group of fungal pathogens closely associated with bees. We tested three fungal species, Ascosphaera apis, Ascosphaera aggregata and Ascosphaera larvis, in two bee hosts (Apis mellifera and Megachile rotundata). Bee survival was not significantly different in mixed infections vs. solo infections with the most virulent pathogen for either host, but fungal growth within the host was significantly altered by mixed infections. In the host A. mellifera, only the most virulent pathogen was present in the host post-infection (indicating superinfective properties). In M. rotundata, the most virulent pathogen co-existed with the lesser-virulent one (indicating co-infective properties). We demonstrated that the competitive outcomes of mixed infections were host-specific, indicating strong host specificity among these fungal bee pathogens. Published by Elsevier Inc.

Transcriptional portrait of Actinobacillus pleuropneumoniae during acute disease--potential strategies for survival and persistence in the host.

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Kirstine Klitgaard

Full Text Available BACKGROUND: Gene expression profiles of bacteria in their natural hosts can provide novel insight into the host-pathogen interactions and molecular determinants of bacterial infections. In the present study, the transcriptional profile of the porcine lung pathogen Actinobacillus pleuropneumoniae was monitored during the acute phase of infection in its natural host. METHODOLOGY/PRINCIPAL FINDINGS: Bacterial expression profiles of A. pleuropneumoniae isolated from lung lesions of 25 infected pigs were compared in samples taken 6, 12, 24 and 48 hours post experimental challenge. Within 6 hours, focal, fibrino hemorrhagic lesions could be observed in the pig lungs, indicating that A. pleuropneumoniae had managed to establish itself successfully in the host. We identified 237 differentially regulated genes likely to encode functions required by the bacteria for colonization and survival in the host. This group was dominated by genes involved in various aspects of energy metabolism, especially anaerobic respiration and carbohydrate metabolism. Remodeling of the bacterial envelope and modifications of posttranslational processing of proteins also appeared to be of importance during early infection. The results suggested that A. pleuropneumoniae is using various strategies to increase its fitness, such as applying Na+ pumps as an alternative way of gaining energy. Furthermore, the transcriptional data provided potential clues as to how A. pleuropneumoniae is able to circumvent host immune factors and survive within the hostile environment of host macrophages. This persistence within macrophages may be related to urease activity, mobilization of various stress responses and active evasion of the host defenses by cell surface sialylation. CONCLUSIONS/SIGNIFICANCE: The data presented here highlight the importance of metabolic adjustments to host conditions as virulence factors of infecting microorganisms and help to provide insight into the mechanisms

Recombination every day: abundant recombination in a virus during a single multi-cellular host infection.

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Remy Froissart

2005-03-01

Full Text Available Viral recombination can dramatically impact evolution and epidemiology. In viruses, the recombination rate depends on the frequency of genetic exchange between different viral genomes within an infected host cell and on the frequency at which such co-infections occur. While the recombination rate has been recently evaluated in experimentally co-infected cell cultures for several viruses, direct quantification at the most biologically significant level, that of a host infection, is still lacking. This study fills this gap using the cauliflower mosaic virus as a model. We distributed four neutral markers along the viral genome, and co-inoculated host plants with marker-containing and wild-type viruses. The frequency of recombinant genomes was evaluated 21 d post-inoculation. On average, over 50% of viral genomes recovered after a single host infection were recombinants, clearly indicating that recombination is very frequent in this virus. Estimates of the recombination rate show that all regions of the genome are equally affected by this process. Assuming that ten viral replication cycles occurred during our experiment-based on data on the timing of coat protein detection-the per base and replication cycle recombination rate was on the order of 2 x 10(-5 to 4 x 10(-5. This first determination of a virus recombination rate during a single multi-cellular host infection indicates that recombination is very frequent in the everyday life of this virus.

Comparative proteomics analysis of Spodoptera frugiperda cells during Autographa californica multiple nucleopolyhedrovirus infection.

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Yu, Qian; Xiong, Youhua; Gao, Hang; Liu, Jianliang; Chen, Zhiqiang; Wang, Qin; Wen, Dongling

2015-08-04

Increasing evidence sugggest that in addition of balculovirus controling insect host, host cells also responds to balculovirus infection. However, compared to existing knowledge on virus gene, host cell responses are relatively poorly understood. In this study, Spodoptera frugiperda (Sf9) cells were infected with Autographa californica multiple nucleopolyhedrovirus (AcMNPV). The protein composition and protein changes of Spodoptera frugiperda (Sf9) cells of different infection stages were analysed by isobaric tag for relative and absolute quantification (iTRAQ) techniques. A total of 4004 Sf9 proteins were identified by iTRAQ and 413 proteins were found as more than 1.5-fold changes in abundance. The 413 proteins were categorised according to GO classification for insects and were categorised into: biological process, molecular function and cellular component. The determination of the protein changes in infected Sf9 cells would help to better understanding of host cell responses and facilitate better design of this virus-host cell interaction in pest insect control and other related fields.

Polypeptide synthesis in alphavirus-infected aedes albopictus cells during the establishment of persistent infection

International Nuclear Information System (INIS)

Richardson, M.A.; Boulton, R.W.; Raghow, R.S.; Dalgarno, L.

1980-01-01

Polypeptide synthesis was examined in mosquito cells during the establishment of a persistent infection with two alphaviruses, Ross River virus (RRV) and Semliki Forest virus (SFV), and in vertebrate cells cytopathically-infected with the same viruses. In Aedes albopictus cells, RRV reached peak titres at 34-48 hours p.i. At 12 hours 85 per cent of cells assayed as infected by infective centre assay; by 48 hours when persistence was established, virus production was reduced and <5 per cent of cells assayed as infected. There was not shutdown of host polypeptide synthesis during infection. Viral polypeptide synthesis was maximal between 10 and 24 hours p.i. The major viral polypeptides labelled were nucleocapsid protein and envelope protein(s).The precursor polypeptide p95 which was prominent in infected BHK cells was not detected in mosquito cells. Similar results were obtained on SFV infection. During the establishment of persistence there was a coordinate decline in the synthesis of RRV polypeptides, reaching undetectable levels by 72 hours p.i. Subculturing persistently-infected cells led to a small increase in viral polypeptide synthesis and virus titre. In contrast, during RRV growth in BHK cells host protein synthesis was severely inhibited and by 9-11 hours p.i. virus-specific polypeptide synthesis represented more than 90 per cent of total protein synthetic activity. (author)

Deciphering the landscape of host barriers to Listeria monocytogenes infection.

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Zhang, Ting; Abel, Sören; Abel Zur Wiesch, Pia; Sasabe, Jumpei; Davis, Brigid M; Higgins, Darren E; Waldor, Matthew K

2017-06-13

Listeria monocytogenes is a common food-borne pathogen that can disseminate from the intestine and infect multiple organs. Here, we used sequence tag-based analysis of microbial populations (STAMP) to investigate L monocytogenes population dynamics during infection. We created a genetically barcoded library of murinized L monocytogenes and then used deep sequencing to track the pathogen's dissemination routes and quantify its founding population ( N b ) sizes in different organs. We found that the pathogen disseminates from the gastrointestinal tract to distal sites through multiple independent routes and that N b sizes vary greatly among tissues, indicative of diverse host barriers to infection. Unexpectedly, comparative analyses of sequence tags revealed that fecally excreted organisms are largely derived from the very small number of L. monocytogenes cells that colonize the gallbladder. Immune depletion studies suggest that distinct innate immune cells restrict the pathogen's capacity to establish replicative niches in the spleen and liver. Finally, studies in germ-free mice suggest that the microbiota plays a critical role in the development of the splenic, but not the hepatic, barriers that prevent L. monocytogenes from seeding these organs. Collectively, these observations illustrate the potency of the STAMP approach to decipher the impact of host factors on population dynamics of pathogens during infection.

Host and Pathogen Copper-Transporting P-Type ATPases Function Antagonistically during Salmonella Infection.

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Ladomersky, Erik; Khan, Aslam; Shanbhag, Vinit; Cavet, Jennifer S; Chan, Jefferson; Weisman, Gary A; Petris, Michael J

2017-09-01

Copper is an essential yet potentially toxic trace element that is required by all aerobic organisms. A key regulator of copper homeostasis in mammalian cells is the copper-transporting P-type ATPase ATP7A, which mediates copper transport from the cytoplasm into the secretory pathway, as well as copper export across the plasma membrane. Previous studies have shown that ATP7A-dependent copper transport is required for killing phagocytosed Escherichia coli in a cultured macrophage cell line. In this investigation, we expanded on these studies by generating Atp7a LysMcre mice, in which the Atp7a gene was specifically deleted in cells of the myeloid lineage, including macrophages. Primary macrophages isolated from Atp7a LysMcre mice exhibit decreased copper transport into phagosomal compartments and a reduced ability to kill Salmonella enterica serovar Typhimurium compared to that of macrophages isolated from wild-type mice. The Atp7a LysMcre mice were also more susceptible to systemic infection by S Typhimurium than wild-type mice. Deletion of the S Typhimurium copper exporters, CopA and GolT, was found to decrease infection in wild-type mice but not in the Atp7a LysMcre mice. These studies suggest that ATP7A-dependent copper transport into the phagosome mediates host defense against S Typhimurium, which is counteracted by copper export from the bacteria via CopA and GolT. These findings reveal unique and opposing functions for copper transporters of the host and pathogen during infection. Copyright © 2017 American Society for Microbiology.

Analysis of differentially expressed proteins in Yersinia enterocolitica-infected HeLa cells.

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Alugubelly, Navatha; Hercik, Kamil; Kibler, Peter; Nanduri, Bindu; Edelmann, Mariola J

2016-05-01

Yersinia enterocolitica is a facultative intracellular pathogen and a causative agent of yersiniosis, which can be contracted by ingestion of contaminated food. Yersinia secretes virulence factors to subvert critical pathways in the host cell. In this study we utilized shotgun label-free proteomics to study differential protein expression in epithelial cells infected with Y.enterocolitica. We identified a total of 551 proteins, amongst which 42 were downregulated (including Prostaglandin E Synthase 3, POH-1 and Karyopherin alpha) and 22 were upregulated (including Rab1 and RhoA) in infected cells. We validated some of these results by western blot analysis of proteins extracted from Caco-2 and HeLa cells. The proteomic dataset was used to identify host canonical pathways and molecular functions modulated by this infection in the host cells. This study constitutes a proteome of Yersinia-infected cells and can support new discoveries in the area of host-pathogen interactions. We describe a proteome of Yersinia enterocolitica-infected HeLa cells, including a description of specific proteins differentially expressed upon infection, molecular functions as well as pathways altered during infection. This proteomic study can lead to a better understanding of Y. enterocolitica pathogenesis in human epithelial cells. Copyright © 2016. Published by Elsevier B.V.

Early Trypanosoma cruzi Infection Reprograms Human Epithelial Cells

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María Laura Chiribao

2014-01-01

Full Text Available Trypanosoma cruzi, the causative agent of Chagas disease, has the peculiarity, when compared with other intracellular parasites, that it is able to invade almost any type of cell. This property makes Chagas a complex parasitic disease in terms of prophylaxis and therapeutics. The identification of key host cellular factors that play a role in the T. cruzi invasion is important for the understanding of disease pathogenesis. In Chagas disease, most of the focus is on the response of macrophages and cardiomyocytes, since they are responsible for host defenses and cardiac lesions, respectively. In the present work, we studied the early response to infection of T. cruzi in human epithelial cells, which constitute the first barrier for establishment of infection. These studies identified up to 1700 significantly altered genes regulated by the immediate infection. The global analysis indicates that cells are literally reprogrammed by T. cruzi, which affects cellular stress responses (neutrophil chemotaxis, DNA damage response, a great number of transcription factors (including the majority of NFκB family members, and host metabolism (cholesterol, fatty acids, and phospholipids. These results raise the possibility that early host cell reprogramming is exploited by the parasite to establish the initial infection and posterior systemic dissemination.

ARF6, PI3-kinase and host cell actin cytoskeleton in Toxoplasma gondii cell invasion

International Nuclear Information System (INIS)

Vieira da Silva, Claudio; Alves da Silva, Erika; Costa Cruz, Mario; Chavrier, Philippe; Arruda Mortara, Renato

2009-01-01

Toxoplasma gondii infects a variety of different cell types in a range of different hosts. Host cell invasion by T. gondii occurs by active penetration of the host cell, a process previously described as independent of host actin polymerization. Also, the parasitophorous vacuole has been shown to resist fusion with endocytic and exocytic pathways of the host cell. ADP-ribosylation factor-6 (ARF6) belongs to the ARF family of small GTP-binding proteins. ARF6 regulates membrane trafficking and actin cytoskeleton rearrangements at the plasma membrane. Here, we have observed that ARF6 is recruited to the parasitophorous vacuole of tachyzoites of T. gondii RH strain and it also plays an important role in the parasite cell invasion with activation of PI3-kinase and recruitment of PIP 2 and PIP 3 to the parasitophorous vacuole of invading parasites. Moreover, it was verified that maintenance of host cell actin cytoskeleton integrity is important to parasite invasion.

Shigella infection of intestinal epithelium and circumvention of the host innate defense system.

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Ashida, Hiroshi; Ogawa, Michinaga; Mimuro, Hitomi; Sasakawa, Chihiro

2009-01-01

Shigella, Gram-negative bacteria closely related to Escherichia coli, are highly adapted human pathogens that cause bacillary dysentery. Although Shigella have neither adherence factors nor flagella required for attaching or accessing the intestinal epithelium, Shigella are capable of colonizing the intestinal epithelium by exploiting epithelial-cell functions and circumventing the host innate immune response. During Shigella infection, they deliver many numbers of effectors through the type III secretion system into the surrounding space and directly into the host-cell cytoplasm. The effectors play pivotal roles from the onset of bacterial infection through to the establishment of the colonization of the intestinal epithelium, such as bacterial invasion, intracellular survival, subversion of the host immune defense response, and maintenance of the infectious foothold. These examples suggest that Shigella have evolved highly sophisticated infectious and intracellular strategies to establish replicative niches in the intestinal epithelium.

Identification of microRNAs Involved in the Host Response to Enterovirus 71 Infection by a Deep Sequencing Approach

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Lunbiao Cui

2010-01-01

Full Text Available Role of microRNA (miRNA has been highlighted in pathogen-host interactions recently. To identify cellular miRNAs involved in the host response to enterovirus 71 (EV71 infection, we performed a comprehensive miRNA profiling in EV71-infected Hep2 cells through deep sequencing. 64 miRNAs were found whose expression levels changed for more than 2-fold in response to EV71 infection. Gene ontology analysis revealed that many of these mRNAs play roles in neurological process, immune response, and cell death pathways, which are known to be associated with the extreme virulence of EV71. To our knowledge, this is the first study on host miRNAs expression alteration response to EV71 infection. Our findings supported the hypothesis that certain miRNAs might be essential in the host-pathogen interactions.

Telomerase Activity Impacts on Epstein-Barr Virus Infection of AGS Cells

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Rac, Jürgen; Haas, Florian; Schumacher, Andrina; Middeldorp, Jaap M.; Delecluse, Henri-Jacques; Speck, Roberto F.

2015-01-01

The Epstein-Barr virus (EBV) is transmitted from host-to-host via saliva and is associated with epithelial malignancies including nasopharyngeal carcinoma (NPC) and some forms of gastric carcinoma (GC). Nevertheless, EBV does not transform epithelial cells in vitro where it is rapidly lost from infected primary epithelial cells or epithelial tumor cells. Long-term infection by EBV, however, can be established in hTERT-immortalized nasopharyngeal epithelial cells. Here, we hypothesized that increased telomerase activity in epithelial cells enhances their susceptibility to infection by EBV. Using HONE-1, AGS and HEK293 cells we generated epithelial model cell lines with increased or suppressed telomerase activity by stable ectopic expression of hTERT or of a catalytically inactive, dominant negative hTERT mutant. Infection experiments with recombinant prototypic EBV (rB95.8), recombinant NPC EBV (rM81) with increased epithelial cell tropism compared to B95.8, or recombinant B95.8 EBV with BZLF1-knockout that is not able to undergo lytic replication, revealed that infection frequencies positively correlate with telomerase activity in AGS cells but also partly depend on the cellular background. AGS cells with increased telomerase activity showed increased expression mainly of latent EBV genes, suggesting that increased telomerase activity directly acts on the EBV infection of epithelial cells by facilitating latent EBV gene expression early upon virus inoculation. Thus, our results indicate that infection of epithelial cells by EBV is a very selective process involving, among others, telomerase activity and cellular background to allow for optimized host-to-host transmission via saliva. PMID:25856387

Dual analysis of the murine cytomegalovirus and host cell transcriptomes reveal new aspects of the virus-host cell interface.

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Vanda Juranic Lisnic

Full Text Available Major gaps in our knowledge of pathogen genes and how these gene products interact with host gene products to cause disease represent a major obstacle to progress in vaccine and antiviral drug development for the herpesviruses. To begin to bridge these gaps, we conducted a dual analysis of Murine Cytomegalovirus (MCMV and host cell transcriptomes during lytic infection. We analyzed the MCMV transcriptome during lytic infection using both classical cDNA cloning and sequencing of viral transcripts and next generation sequencing of transcripts (RNA-Seq. We also investigated the host transcriptome using RNA-Seq combined with differential gene expression analysis, biological pathway analysis, and gene ontology analysis. We identify numerous novel spliced and unspliced transcripts of MCMV. Unexpectedly, the most abundantly transcribed viral genes are of unknown function. We found that the most abundant viral transcript, recently identified as a noncoding RNA regulating cellular microRNAs, also codes for a novel protein. To our knowledge, this is the first viral transcript that functions both as a noncoding RNA and an mRNA. We also report that lytic infection elicits a profound cellular response in fibroblasts. Highly upregulated and induced host genes included those involved in inflammation and immunity, but also many unexpected transcription factors and host genes related to development and differentiation. Many top downregulated and repressed genes are associated with functions whose roles in infection are obscure, including host long intergenic noncoding RNAs, antisense RNAs or small nucleolar RNAs. Correspondingly, many differentially expressed genes cluster in biological pathways that may shed new light on cytomegalovirus pathogenesis. Together, these findings provide new insights into the molecular warfare at the virus-host interface and suggest new areas of research to advance the understanding and treatment of cytomegalovirus

Putative alternative polyadenylation (APA) events in the early interaction of Salmonella enterica Typhimurium and human host cells.

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Afonso-Grunz, Fabian

2015-12-01

The immune response of epithelial cells upon infection is mediated by changing activity levels of a variety of proteins along with changes in mRNA, and also ncRNA abundance. Alternative polyadenylation (APA) represents a mechanism that diversifies gene expression similar to alternative splicing. T-cell activation, neuronal activity, development and several human diseases including viral infections involve APA, but at present it remains unclear if this mechanism is also implicated in the response to bacterial infections. Our recently published study of interacting Salmonella enterica Typhimurium and human host cells includes genome-wide expression profiles of human epithelial cells prior and subsequent to infection with the invasive pathogen. The generated dataset (GEO accession number: GSE61730) covers several points of time post infection, and one of these interaction stages was additionally profiled with MACE-based dual 3'Seq, which allows for identification of polyadenylation (PA) sites. The present study features the polyadenylation landscape in early interacting cells based on this data, and provides a comparison of the identified PA sites with those of a corresponding 3P-Seq dataset of non-interacting cells. Differential PA site usage of FTL , PRDX1 and VAPA results in transcription of mRNA isoforms with distinct sets of miRNA and protein binding sites that influence processing, localization, stability, and translation of the respective mRNA. APA of these candidate genes consequently harbors the potential to modulate the host cell response to bacterial infection.

Putative alternative polyadenylation (APA events in the early interaction of Salmonella enterica Typhimurium and human host cells

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Fabian Afonso-Grunz

2015-12-01

Full Text Available The immune response of epithelial cells upon infection is mediated by changing activity levels of a variety of proteins along with changes in mRNA, and also ncRNA abundance. Alternative polyadenylation (APA represents a mechanism that diversifies gene expression similar to alternative splicing. T-cell activation, neuronal activity, development and several human diseases including viral infections involve APA, but at present it remains unclear if this mechanism is also implicated in the response to bacterial infections. Our recently published study of interacting Salmonella enterica Typhimurium and human host cells includes genome-wide expression profiles of human epithelial cells prior and subsequent to infection with the invasive pathogen. The generated dataset (GEO accession number: GSE61730 covers several points of time post infection, and one of these interaction stages was additionally profiled with MACE-based dual 3'Seq, which allows for identification of polyadenylation (PA sites. The present study features the polyadenylation landscape in early interacting cells based on this data, and provides a comparison of the identified PA sites with those of a corresponding 3P-Seq dataset of non-interacting cells. Differential PA site usage of FTL, PRDX1 and VAPA results in transcription of mRNA isoforms with distinct sets of miRNA and protein binding sites that influence processing, localization, stability, and translation of the respective mRNA. APA of these candidate genes consequently harbors the potential to modulate the host cell response to bacterial infection.

Human innate lymphoid cells (ILCs) in filarial infections.

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Bonne-Année, S; Nutman, T B

2018-02-01

Filarial infections are characteristically chronic and can cause debilitating diseases governed by parasite-induced innate and adaptive immune responses. Filarial parasites traverse or establish niches in the skin (migrating infective larvae), in nonmucosal tissues (adult parasite niche) and in the blood or skin (circulating microfilariae) where they intersect with the host immune response. While several studies have demonstrated that filarial parasites and their antigens can modulate myeloid cells (monocyte, macrophage and dendritic cell subsets), T- and B-lymphocytes and skin resident cell populations, the role of innate lymphoid cells during filarial infections has only recently emerged. Despite the identification and characterization of innate lymphoid cells (ILCs) in murine helminth infections, little is actually known about the role of human ILCs during parasitic infections. The focus of this review will be to highlight the composition of ILCs in the skin, lymphatics and blood; where the host-parasite interaction is well-defined and to examine the role of ILCs during filarial infections. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Cross-species infection trials reveal cryptic parasite varieties and a putative polymorphism shared among host species.

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Luijckx, Pepijn; Duneau, David; Andras, Jason P; Ebert, Dieter

2014-02-01

A parasite's host range can have important consequences for ecological and evolutionary processes but can be difficult to infer. Successful infection depends on the outcome of multiple steps and only some steps of the infection process may be critical in determining a parasites host range. To test this hypothesis, we investigated the host range of the bacterium Pasteuria ramosa, a Daphnia parasite, and determined the parasites success in different stages of the infection process. Multiple genotypes of Daphnia pulex, Daphnia longispina and Daphnia magna were tested with four Pasteuria genotypes using infection trials and an assay that determines the ability of the parasite to attach to the hosts esophagus. We find that attachment is not specific to host species but is specific to host genotype. This may suggest that alleles on the locus controlling attachment are shared among different host species that diverged 100 million year. However, in our trials, Pasteuria was never able to reproduce in nonnative host species, suggesting that Pasteuria infecting different host species are different varieties, each with a narrow host range. Our approach highlights the explanatory power of dissecting the steps of the infection process and resolves potentially conflicting reports on parasite host ranges. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Trichomonas vaginalis exosomes deliver cargo to host cells and mediate host∶parasite interactions.

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Olivia Twu

Full Text Available Trichomonas vaginalis is a common sexually transmitted parasite that colonizes the human urogential tract where it remains extracellular and adheres to epithelial cells. Infections range from asymptomatic to highly inflammatory, depending on the host and the parasite strain. Here, we use a combination of methodologies including cell fractionation, immunofluorescence and electron microscopy, RNA, proteomic and cytokine analyses and cell adherence assays to examine pathogenic properties of T. vaginalis. We have found that T.vaginalis produces and secretes microvesicles with physical and biochemical properties similar to mammalian exosomes. The parasite-derived exosomes are characterized by the presence of RNA and core, conserved exosomal proteins as well as parasite-specific proteins. We demonstrate that T. vaginalis exosomes fuse with and deliver their contents to host cells and modulate host cell immune responses. Moreover, exosomes from highly adherent parasite strains increase the adherence of poorly adherent parasites to vaginal and prostate epithelial cells. In contrast, exosomes from poorly adherent strains had no measurable effect on parasite adherence. Exosomes from parasite strains that preferentially bind prostate cells increased binding of parasites to these cells relative to vaginal cells. In addition to establishing that parasite exosomes act to modulate host∶parasite interactions, these studies are the first to reveal a potential role for exosomes in promoting parasite∶parasite communication and host cell colonization.

Persistence, impacts and environmental drivers of covert infections in invertebrate hosts

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Inês Fontes

2017-11-01

Full Text Available Abstract Background Persistent covert infections of the myxozoan, Tetracapsuloides bryosalmonae, in primary invertebrate hosts (the freshwater bryozoan, Fredericella sultana have been proposed to represent a reservoir for proliferative kidney disease in secondary fish hosts. However, we have limited understanding of how covert infections persist and vary in bryozoan populations over time and space and how they may impact these populations. In addition, previous studies have likely underestimated covert infection prevalence. To improve our understanding of the dynamics, impacts and implications of covert infections we employed a highly sensitive polymerase chain reaction (PCR assay and undertook the first investigation of covert infections in the field over an annual period by sampling bryozoans every 45 days from three populations within each of three rivers. Results Covert infections persisted throughout the year and prevalence varied within and between rivers, but were often > 50%. Variation in temperature and water chemistry were linked with changes in prevalence in a manner consistent with the maintenance of covert infections during periods of low productivity and thus poor growth conditions for both bryozoans and T. bryosalmonae. The presence and increased severity of covert infections reduced host growth but only when bryozoans were also investing in the production of overwintering propagules (statoblasts. However, because statoblast production is transitory, this effect is unlikely to greatly impact the capacity of bryozoan populations to act as persistent sources of infections and hence potential disease outbreaks in farmed and wild fish populations. Conclusions We demonstrate that covert infections are widespread and persist over space and time in bryozoan populations. To our knowledge, this is the first long-term study of covert infections in a field setting. Review of the results of this and previous studies enables us to identify

Host social behavior and parasitic infection: A multifactorial approach

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Ezenwa, V.O.

2004-01-01

I examined associations between several components of host social organization, including group size and gregariousness, group stability, territoriality and social class, and gastrointestinal parasite load in African bovids. At an intraspecific level, group size was positively correlated with parasite prevalence, but only when the parasite was relatively host specific and only among host species living in stable groups. Social class was also an important predictor of infection rates. Among gazelles, territorial males had higher parasite intensities than did either bachelor males or females and juveniles, suggesting that highly territorial individuals may be either more exposed or more susceptible to parasites. Associations among territoriality, grouping, and parasitism were also found across taxa. Territorial host genera were more likely to be infected with strongyle nematodes than were nonterritorial hosts, and gregarious hosts were more infected than were solitary hosts. Analyses also revealed that gregariousness and territoriality had an interactive effect on individual parasite richness, whereby hosts with both traits harbored significantly more parasite groups than did hosts with only one or neither trait. Overall, study results indicate that multiple features of host social behavior influence infection risk and suggest that synergism between traits also has important effects on host parasite load.

Phage adsorption and lytic propagation in Lactobacillus plantarum: Could host cell starvation affect them?

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Briggiler Marc?, Mari?ngeles; Reinheimer, Jorge; Quiberoni, Andrea

2015-01-01

Background Bacteriophages constitute a great threat to the activity of lactic acid bacteria used in industrial processes. Several factors can influence the infection cycle of bacteriophages. That is the case of the physiological state of host cells, which could produce inhibition or delay of the phage infection process. In the present work, the influence of Lactobacillus plantarum host cell starvation on phage B1 adsorption and propagation was investigated. Result First, cell growth kinetics ...

Activation of Natural Killer cells during microbial infections

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Amir eHorowitz

2012-01-01

Full Text Available Natural killer (NK cells are large granular lymphocytes that express a diverse array of germline encoded inhibitory and activating receptors for MHC Class I and Class I-like molecules, classical co-stimulatory ligands and cytokines. The ability of NK cells to be very rapidly activated by inflammatory cytokines, to secrete effector cytokines and to kill infected or stressed host cells, suggests that they may be among the very early responders during infection. Recent studies have also identified a small number of pathogen-derived ligands that can bind to NK cell surface receptors and directly induce their activation. Here we review recent studies that have begun to elucidate the various pathways by which viral, bacterial and parasite pathogens activate NK cells. We also consider two emerging themes of NK cell-pathogen interactions, namely their contribution to adaptive immune responses and their potential to take on regulatory and immunomodulatory functions.

Cell wall glycoproteins at interaction sites between parasitic giant dodder (Cuscuta reflexa) and its host Pelargonium zonale.

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Striberny, Bernd; Krause, Kirsten

2015-01-01

The process of host plant penetration by parasitic dodder (genus Cuscuta) is accompanied by molecular and structural changes at the host/parasite interface. Recently, changes in pectin methyl esterification levels in the host cell walls abutting parasitic cells in established infection sites were reported. In addition to that, we show here that the composition of cell wall glycoproteins in Cuscuta-infected Pelargonium zonale undergoes substantial changes. While several arabinogalactan protein epitopes exhibit decreased abundances in the vicinity of the Cuscuta reflexa haustorium, extensins tend to increase in the infected areas.

Temperature shift and host cell contact up-regulate sporozoite expression of Plasmodium falciparum genes involved in hepatocyte infection.

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Anthony Siau

Full Text Available Plasmodium sporozoites are deposited in the skin by Anopheles mosquitoes. They then find their way to the liver, where they specifically invade hepatocytes in which they develop to yield merozoites infective to red blood cells. Relatively little is known of the molecular interactions during these initial obligatory phases of the infection. Recent data suggested that many of the inoculated sporozoites invade hepatocytes an hour or more after the infective bite. We hypothesised that this pre-invasive period in the mammalian host prepares sporozoites for successful hepatocyte infection. Therefore, the genes whose expression becomes modified prior to hepatocyte invasion would be those likely to code for proteins implicated in the subsequent events of invasion and development. We have used P. falciparum sporozoites and their natural host cells, primary human hepatocytes, in in vitro co-culture system as a model for the pre-invasive period. We first established that under co-culture conditions, sporozoites maintain infectivity for an hour or more, in contrast to a drastic loss in infectivity when hepatocytes were not included. Thus, a differential transcriptome of salivary gland sporozoites versus sporozoites co-cultured with hepatocytes was established using a pan-genomic P. falciparum microarray. The expression of 532 genes was found to have been up-regulated following co-culture. A fifth of these genes had no orthologues in the genomes of Plasmodium species used in rodent models of malaria. Quantitative RT-PCR analysis of a selection of 21 genes confirmed the reliability of the microarray data. Time-course analysis further indicated two patterns of up-regulation following sporozoite co-culture, one transient and the other sustained, suggesting roles in hepatocyte invasion and liver stage development, respectively. This was supported by functional studies of four hitherto uncharacterized proteins of which two were shown to be sporozoite surface

Infection Unit Density as an Index of Infection Potential of Arbuscular Mycorrhizal Fungi.

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Ohtomo, Ryo; Kobae, Yoshihiro; Morimoto, Sho; Oka, Norikuni

2018-03-29

The effective use of arbuscular mycorrhizal (AM) fungal function to promote host plant phosphate uptake in agricultural practice requires the accurate quantitative evaluation of AM fungal infection potential in field soil or AM fungal inoculation material. The number of infection units (IUs), intraradical fungal structures derived from single root entries formed after a short cultivation period, may reflect the number of propagules in soil when pot soil is completely permeated by the host root. However, the original IU method, in which all AM propagules in a pot are counted, requires the fine tuning of plant growing conditions and is considered to be laborious. The objective of the present study was to test whether IU density, not the total count of IU, but the number of IUs per unit root length, reflects the density of AM fungal propagules in soil. IU density assessed after 12 d of host plant cultivation and 3,3'-diaminobenzidine (DAB) staining showed a stronger linear correlation with propagule density than the mean infection percentage (MIP). In addition, IU density was affected less by the host plant species than MIP. We suggest that IU density provides a more rapid and reliable quantitation of the propagule density of AM fungi than MIP or the original IU method. Thus, IU density may be a more robust index of AM fungal infection potential for research and practical applications.

Invasion of Eukaryotic Cells by Legionella Pneumophila: A Common Strategy for all Hosts?

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Paul S Hoffman

1997-01-01

Full Text Available Legionella pneumophila is an environmental micro-organism capable of producing an acute lobar pneumonia, commonly referred to as Legionnaires’ disease, in susceptible humans. Legionellae are ubiquitous in aquatic environments, where they survive in biofilms or intracellularly in various protozoans. Susceptible humans become infected by breathing aerosols laden with the bacteria. The target cell for human infection is the alveolar macrophage, in which the bacteria abrogate phagolysosomal fusion. The remarkable ability of L pneumophila to infect a wide range of eukaryotic cells suggests a common strategy that exploits very fundamental cellular processes. The bacteria enter host cells via coiling phagocytosis and quickly subvert organelle trafficking events, leading to formation of a replicative phagosome in which the bacteria multiply. Vegetative growth continues for 8 to 10 h, after which the bacteria develop into a short, highly motile form called the ‘mature form’. The mature form exhibits a thickening of the cell wall, stains red with the Gimenez stain, and is between 10 and 100 times more infectious than agar-grown bacteria. Following host cell lysis, the released bacteria infect other host cells, in which the mature form differentiates into a Gimenez-negative vegetative form, and the cycle begins anew. Virulence of L pneumophila is considered to be multifactorial, and there is growing evidence for both stage specific and sequential gene expression. Thus, L pneumophila may be a good model system for dissecting events associated with the host-parasite interactions.

The cytotoxic type 3 secretion system 1 of Vibrio rewires host gene expression to subvert cell death and activate cell survival pathways.

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De Nisco, Nicole J; Kanchwala, Mohammed; Li, Peng; Fernandez, Jessie; Xing, Chao; Orth, Kim

2017-05-16

Bacterial effectors potently manipulate host signaling pathways. The marine bacterium Vibrio parahaemolyticus ( V. para ) delivers effectors into host cells through two type 3 secretion systems (T3SSs). T3SS1 is vital for V. para survival in the environment, whereas T3SS2 causes acute gastroenteritis in human hosts. Although the natural host is undefined, T3SS1 effectors attack highly conserved cellular processes and pathways to orchestrate nonapoptotic cell death. To understand how the concerted action of T3SS1 effectors globally affects host cell signaling, we compared gene expression changes over time in primary fibroblasts infected with V. para that have a functional T3SS1 (T3SS1 + ) to those in cells infected with V. para lacking T3SS1 (T3SS1 - ). Overall, the host transcriptional response to both T3SS1 + and T3SS1 - V. para was rapid, robust, and temporally dynamic. T3SS1 rewired host gene expression by specifically altering the expression of 398 genes. Although T3SS1 effectors targeted host cells at the posttranslational level to cause cytotoxicity, V. para T3SS1 also precipitated a host transcriptional response that initially activated cell survival and repressed cell death networks. The increased expression of several key prosurvival transcripts mediated by T3SS1 depended on a host signaling pathway that is silenced posttranslationally later in infection. Together, our analysis reveals a complex interplay between the roles of T3SS1 as both a transcriptional and posttranslational manipulator of host cell signaling. Copyright © 2017, American Association for the Advancement of Science.

Gene expression profiling of the host response to HIV-1 B, C, or A/E infection in monocyte-derived dendritic cells

International Nuclear Information System (INIS)

Solis, Mayra; Wilkinson, Peter; Romieu, Raphaelle; Hernandez, Eduardo; Wainberg, Mark A.; Hiscott, John

2006-01-01

Dendritic cells (DC) are among the first targets of human immunodeficiency virus type-1 (HIV-1) infection and in turn play a crucial role in viral transmission to T cells and in the regulation of the immune response. The major group of HIV-1 has diversified genetically based on variation in env sequences and comprise at least 11 subtypes. Because little is known about the host response elicited against different HIV-1 clade isolates in vivo, we sought to use gene expression profiling to identify genes regulated by HIV-1 subtypes B, C, and A/E upon de novo infection of primary immature monocyte-derived DC (iMDDCs). A total of 3700 immune-related genes were subjected to a significance analysis of microarrays (SAM); 656 genes were selected as significant and were further divided into 8 functional categories. Regardless of the time of infection, 20% of the genes affected by HIV-1 were involved in signal transduction, followed by 14% of the genes identified as transcription-related genes, and 7% were classified as playing a role in cell proliferation and cell cycle. Furthermore, 7% of the genes were immune response genes. By 72 h postinfection, genes upregulated by subtype B included the inhibitor of the matrix metalloproteinase TIMP2 and the heat shock protein 40 homolog (Hsp40) DNAJB1, whereas the IFN inducible gene STAT1, the MAPK1/ERK2 kinase regulator ST5, and the chemokine CXCL3 and SHC1 genes were induced by subtypes C and A/E. These analyses distinguish a temporally regulated host response to de novo HIV-1 infection in primary dendritic cells

Estimating immunoregulatory gene networks in human herpesvirus type 6-infected T cells

International Nuclear Information System (INIS)

Takaku, Tomoiku; Ohyashiki, Junko H.; Zhang, Yu; Ohyashiki, Kazuma

2005-01-01

The immune response to viral infection involves complex network of dynamic gene and protein interactions. We present here the dynamic gene network of the host immune response during human herpesvirus type 6 (HHV-6) infection in an adult T-cell leukemia cell line. Using a pathway-focused oligonucleotide DNA microarray, we found a possible association between chemokine genes regulating Th1/Th2 balance and genes regulating T-cell proliferation during HHV-6B infection. Gene network analysis using an integrated comprehensive workbench, VoyaGene, revealed that a gene encoding a TEC-family kinase, ITK, might be a putative modulator in the host immune response against HHV-6B infection. We conclude that Th2-dominated inflammatory reaction in host cells may play an important role in HHV-6B-infected T cells, thereby suggesting the possibility that ITK might be a therapeutic target in diseases related to dysregulation of Th1/Th2 balance. This study describes a novel approach to find genes related with the complex host-virus interaction using microarray data employing the Bayesian statistical framework

Contemporary theories of cervical carcinogenesis: the virus, the host, and the stem cell.

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Crum, C P

2000-03-01

Cervical cancer is a complex disease that, by its association with human papillomavirus (HPV), has elicited research in a broad range of areas pertaining to its basic diagnostic and clinical aspects. The complexity of this association lies not only in the fundamental relationship between virus and cancer but also in its translation to pathologic diagnosis and clinical management. Offshoots from the relationship of virus to pathology include studies targeting the link between papillomavirus infection and cervical epithelial abnormalities, the molecular epidemiology of papillomavirus infection, and the potential use of HPV testing as either a screening technique or a tool for managing women who have Pap smear abnormalities. A second variable that is critical to the pathogenesis of cervical neoplasia is the cervical transformation zone. The wide range of invasive and noninvasive lesion phenotypes associated with HPV infection in this region indicate that not only the virus but also specific host target epithelial cells in the transformation zone play an important part in the development of cervical neoplasia. Further understanding of this relationship between the virus and the host epithelium will hinge on determining the subtypes of epithelial cells in the transformation zone and their phenotypic response to infection. New technologies, such as expression arrays, promise to clarify, if not resolve, the complexity of molecular interactions leading to the multiplicity of tumor phenotypes associated with HPV infection of the uterine cervix.

Cdc42 promotes host defenses against fatal infection

DEFF Research Database (Denmark)

Lee, Keunwook; Boyd, Kelli L; Parekh, Diptiben V

2013-01-01

attempted to specifically delete it in these cells by crossing the Cdc42(fl/fl) mouse with a FSP-1 cre mouse, which is thought to mediate recombination exclusively in fibroblasts. Surprisingly, the FSP-1cre;Cdc42(fl/fl) mice died at 3 weeks of age due to overwhelming suppurative upper airway infections...... showed that in addition to fibroblasts, the FSP-1 cre deleted Cdc42 very efficiently in all leukocytes. Thus, by using this non-specific cre mouse we inadvertently demonstrated the importance of Cdc42 in host protection from lethal infections and suggest a critical role for this small GTPase in innate...

The Host Response in Patients with Sepsis Developing Intensive Care Unit-acquired Secondary Infections.

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van Vught, Lonneke A; Wiewel, Maryse A; Hoogendijk, Arie J; Frencken, Jos F; Scicluna, Brendon P; Klein Klouwenberg, Peter M C; Zwinderman, Aeilko H; Lutter, Rene; Horn, Janneke; Schultz, Marcus J; Bonten, Marc M J; Cremer, Olaf L; van der Poll, Tom

2017-08-15

Sepsis can be complicated by secondary infections. We explored the possibility that patients with sepsis developing a secondary infection while in the intensive care unit (ICU) display sustained inflammatory, vascular, and procoagulant responses. To compare systemic proinflammatory host responses in patients with sepsis who acquire a new infection with those who do not. Consecutive patients with sepsis with a length of ICU stay greater than 48 hours were prospectively analyzed for the development of ICU-acquired infections. Twenty host response biomarkers reflective of key pathways implicated in sepsis pathogenesis were measured during the first 4 days after ICU admission and at the day of an ICU-acquired infection or noninfectious complication. Of 1,237 admissions for sepsis (1,089 patients), 178 (14.4%) admissions were complicated by ICU-acquired infections (at Day 10 [6-13], median with interquartile range). Patients who developed a secondary infection showed higher disease severity scores and higher mortality up to 1 year than those who did not. Analyses of biomarkers in patients who later went on to develop secondary infections revealed a more dysregulated host response during the first 4 days after admission, as reflected by enhanced inflammation, stronger endothelial cell activation, a more disturbed vascular integrity, and evidence for enhanced coagulation activation. Host response reactions were similar at the time of ICU-acquired infectious or noninfectious complications. Patients with sepsis who developed an ICU-acquired infection showed a more dysregulated proinflammatory and vascular host response during the first 4 days of ICU admission than those who did not develop a secondary infection.

Effector Protein Cig2 Decreases Host Tolerance of Infection by Directing Constitutive Fusion of Autophagosomes with the Coxiella-Containing Vacuole

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Lara J. Kohler

2016-07-01

Full Text Available Coxiella burnetii replicates in an acidified lysosome-derived vacuole. Biogenesis of the Coxiella-containing vacuole (CCV requires bacterial effector proteins delivered into host cells by the Dot/Icm secretion system. Genetic and cell biological analysis revealed that an effector protein called Cig2 promotes constitutive fusion of autophagosomes with the CCV to maintain this compartment in an autolysosomal stage of maturation. This distinguishes the CCV from other pathogen-containing vacuoles that are targeted by the host autophagy pathway, which typically confers host resistance to infection by delivering the pathogen to a toxic lysosomal environment. By maintaining the CCV in an autolysosomal stage of maturation, Cig2 enabled CCV homotypic fusion and enhanced bacterial virulence in the Galleria mellonella (wax moth model of infection by a mechanism that decreases host tolerance. Thus, C. burnetii residence in an autolysosomal organelle alters host tolerance of infection, which indicates that Cig2-dependent manipulation of a lysosome-derived vacuole influences the host response to infection.

Host DNA synthesis-suppressing factor in culture fluid of tissue cultures infected with measles virus

International Nuclear Information System (INIS)

Minagawa, T.; Nakaya, C.; Iida, H.

1974-01-01

Host DNA synthesis is suppressed by the culture fluid of cell cultures infected with measles virus. This activity in the culture fluid is initiated somewhat later than the growth of infectious virus. Ninety percent of host DNA synthesis in HeLa cells is inhibited by culture fluid of 3-day-old cell cultures of Vero or HeLa cells infected with measles virus. This suppressing activity is not a property of the virion, but is due to nonvirion-associated componentnent which shows none of the activities of measles virus such as hemagglutination, hemolysis, or cell fusion nor does it have the antigenicity of measles virus as tested by complement-fixation or hemagglutination-inhibiting antibody blocking tests. Neutralization of the activity of this component is not attained with the pooled sera of convalescent measles patients. This component has molecular weights of about 45,000, 20,000, and 3,000 and appears to be a heat-stable protein. The production of host DNA suppressing factor (DSF) is blocked by cycloheximide. Neither uv-inactivated nor antiserum-neutralized measles virus produce DSF. Furthermore, such activity of nonvirion-associated component is not detected in the culture fluid of cultures infected with other RNA viruses such as poliovirus, vesicular stomatitis virus, or Sindbis virus. (auth)

Protective role of host aquaporin 6 against Hazara virus, a model for Crimean-Congo hemorrhagic fever virus infection.

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Molinas, Andrea; Mirazimi, Ali; Holm, Angelika; Loitto, Vesa M; Magnusson, Karl-Eric; Vikström, Elena

2016-04-01

Crimean-Congo hemorrhagic fever virus (CCHFV) is an arthropod-borne pathogen that causes infectious disease with severe hemorrhagic manifestations in vascular system in humans. The proper function of the cells in the vascular system is critically regulated by aquaporins (AQP), water channels that facilitate fluxes of water and small solutes across membranes. With Hazara virus as a model for CCHFV, we investigated the effects of viruses on AQP6 and the impact of AQP6 on virus infectivity in host cells, using transiently expressed GFP-AQP6 cells, immunofluorescent assay for virus detection, epifluorescent imaging of living cells and confocal microscopy. In GFP-AQP6 expressing cells, Hazara virus reduced both the cellular and perinuclear AQP6 distribution and changed the cell area. Infection of human cell with CCHFV strain IbAR 10200 downregulated AQP6 expression at mRNA level. Interestingly, the overexpression of AQP6 in host cells decreased the infectivity of Hazara virus, speaking for a protective role of AQP6. We suggest the possibility for AQP6 being a novel player in the virus-host interactions, which may lead to less severe outcomes of an infection. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

RNA interference silences Microplitis demolitor bracovirus genes and implicates glc1.8 in disruption of adhesion in infected host cells

International Nuclear Information System (INIS)

Beck, Markus; Strand, Michael R.

2003-01-01

The family Polydnaviridae consists of ds-DNA viruses that are symbiotically associated with certain parasitoid wasps. PDVs are transmitted vertically but also are injected by wasps into hosts where they cause several physiological alterations including immunosuppression. The PDV genes responsible for mediating immunosuppression and other host alterations remain poorly characterized in large measure because viral mutants cannot be produced to study gene function. Here we report the use of RNA interference (RNAi) to specifically silence the glc1.8 and egf1.0 genes from Microplitis demolitor bracovirus (MdBV) in High Five cells derived from the lepidopteran Trichoplusia ni. Dose-response studies indicated that MdBV infects High Five cells and blocks the ability of these cells to adhere to culture plates. This response was very similar to what occurs in two classes of hemocytes, granular cells, and plasmatocytes, after infection by MdBV. Screening of monoclonal antibody (mAb) markers that distinguish different classes of lepidopteran hemocytes indicated that High Five cells cross-react with three mAbs that recognize granular cells from T. ni. Double-stranded RNA (dsRNA) complementary to glc1.8 specifically silenced glc1.8 expression and rescued the adhesive phenotype of High Five cells. Reciprocally, dsRNA complementary to egf1.0 silenced egf1.0 expression but had no effect on adhesion. The simplicity and potency of RNAi could be extremely useful for analysis of other PDV genes

Infective Larvae of Brugia malayi Induce Polarization of Host Macrophages that Helps in Immune Evasion

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Aditi Sharma

2018-02-01

Full Text Available Filarial parasites suppress, divert, or polarize the host immune response to aid their survival. However, mechanisms that govern the polarization of host MΦs during early filarial infection are not completely understood. In this study, we infected BALB/c mice with infective larvae stage-3 of Brugia malayi (Bm-L3 and studied their effect on the polarization of splenic MΦs. Results showed that MΦs displayed M2-phenotype by day 3 p.i. characterized by upregulated IL-4, but reduced IL-12 and Prostaglandin-D2 secretion. Increased arginase activity, higher arginase-1 but reduced NOS2 expression and poor phagocytic and antigen processing capacity was also observed. M2 MΦs supported T-cell proliferation and characteristically upregulated p-ERK but downregulated NF-κB-p65 and NF-κB-p50/105. Notably, Bm-L3 synergized with host regulatory T-cells (Tregs and polarized M2 MΦs to regulatory MΦs (Mregs by day 7 p.i., which secreted copious amounts of IL-10 and prostaglandin-E2. Mregs also showed upregulated expression levels of MHC-II, CD80, and CD86 and exhibited increased antigen-processing capacity but displayed impaired activation of NF-κB-p65 and NF-κB-p50/105. Neutralization of Tregs by anti-GITR + anti-CD25 antibodies checked the polarization of M2 MΦs to Mregs, decreased accumulation of regulatory B cells and inflammatory monocytes, and reduced secretion of IL-10, but enhanced IL-4 production and percentages of eosinophils, which led to Bm-L3 killing. In summary, we report hitherto undocumented effects of early Bm-L3 infection on the polarization of splenic MΦs and show how infective larvae deftly utilize the functional plasticity of host MΦs to establish themselves inside the host.

Establishment of Myotis myotis cell lines--model for investigation of host-pathogen interaction in a natural host for emerging viruses.

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Xiaocui He

Full Text Available Bats are found to be the natural reservoirs for many emerging viruses. In most cases, severe clinical signs caused by such virus infections are normally not seen in bats. This indicates differences in the virus-host interactions and underlines the necessity to develop natural host related models to study these phenomena. Due to the strict protection of European bat species, immortalized cell lines are the only alternative to investigate the innate anti-virus immune mechanisms. Here, we report about the establishment and functional characterization of Myotis myotis derived cell lines from different tissues: brain (MmBr, tonsil (MmTo, peritoneal cavity (MmPca, nasal epithelium (MmNep and nervus olfactorius (MmNol after immortalization by SV 40 large T antigen. The usefulness of these cell lines to study antiviral responses has been confirmed by analysis of their susceptibility to lyssavirus infection and the mRNA patterns of immune-relevant genes after poly I:C stimulation. Performed experiments indicated varying susceptibility to lyssavirus infection with MmBr being considerably less susceptible than the other cell lines. Further investigation demonstrated a strong activation of interferon mediated antiviral response in MmBr contributing to its resistance. The pattern recognition receptors: RIG-I and MDA5 were highly up-regulated during rabies virus infection in MmBr, suggesting their involvement in promotion of antiviral responses. The presence of CD14 and CD68 in MmBr suggested MmBr cells are microglia-like cells which play a key role in host defense against infections in the central nervous system (CNS. Thus the expression pattern of MmBr combined with the observed limitation of lyssavirus replication underpin a protective mechanism of the CNS controlling the lyssavirus infection. Overall, the established cell lines are important tools to analyze antiviral innate immunity in M. myotis against neurotropic virus infections and present a valuable

Establishment of Myotis myotis cell lines--model for investigation of host-pathogen interaction in a natural host for emerging viruses.

Science.gov (United States)

He, Xiaocui; Korytář, Tomáš; Zhu, Yaqing; Pikula, Jiří; Bandouchova, Hana; Zukal, Jan; Köllner, Bernd

2014-01-01

Bats are found to be the natural reservoirs for many emerging viruses. In most cases, severe clinical signs caused by such virus infections are normally not seen in bats. This indicates differences in the virus-host interactions and underlines the necessity to develop natural host related models to study these phenomena. Due to the strict protection of European bat species, immortalized cell lines are the only alternative to investigate the innate anti-virus immune mechanisms. Here, we report about the establishment and functional characterization of Myotis myotis derived cell lines from different tissues: brain (MmBr), tonsil (MmTo), peritoneal cavity (MmPca), nasal epithelium (MmNep) and nervus olfactorius (MmNol) after immortalization by SV 40 large T antigen. The usefulness of these cell lines to study antiviral responses has been confirmed by analysis of their susceptibility to lyssavirus infection and the mRNA patterns of immune-relevant genes after poly I:C stimulation. Performed experiments indicated varying susceptibility to lyssavirus infection with MmBr being considerably less susceptible than the other cell lines. Further investigation demonstrated a strong activation of interferon mediated antiviral response in MmBr contributing to its resistance. The pattern recognition receptors: RIG-I and MDA5 were highly up-regulated during rabies virus infection in MmBr, suggesting their involvement in promotion of antiviral responses. The presence of CD14 and CD68 in MmBr suggested MmBr cells are microglia-like cells which play a key role in host defense against infections in the central nervous system (CNS). Thus the expression pattern of MmBr combined with the observed limitation of lyssavirus replication underpin a protective mechanism of the CNS controlling the lyssavirus infection. Overall, the established cell lines are important tools to analyze antiviral innate immunity in M. myotis against neurotropic virus infections and present a valuable tool for a

Establishment of Myotis myotis Cell Lines - Model for Investigation of Host-Pathogen Interaction in a Natural Host for Emerging Viruses

Science.gov (United States)

He, Xiaocui; Korytář, Tomáš; Zhu, Yaqing; Pikula, Jiří; Bandouchova, Hana; Zukal, Jan; Köllner, Bernd

2014-01-01

Bats are found to be the natural reservoirs for many emerging viruses. In most cases, severe clinical signs caused by such virus infections are normally not seen in bats. This indicates differences in the virus-host interactions and underlines the necessity to develop natural host related models to study these phenomena. Due to the strict protection of European bat species, immortalized cell lines are the only alternative to investigate the innate anti-virus immune mechanisms. Here, we report about the establishment and functional characterization of Myotis myotis derived cell lines from different tissues: brain (MmBr), tonsil (MmTo), peritoneal cavity (MmPca), nasal epithelium (MmNep) and nervus olfactorius (MmNol) after immortalization by SV 40 large T antigen. The usefulness of these cell lines to study antiviral responses has been confirmed by analysis of their susceptibility to lyssavirus infection and the mRNA patterns of immune-relevant genes after poly I:C stimulation. Performed experiments indicated varying susceptibility to lyssavirus infection with MmBr being considerably less susceptible than the other cell lines. Further investigation demonstrated a strong activation of interferon mediated antiviral response in MmBr contributing to its resistance. The pattern recognition receptors: RIG-I and MDA5 were highly up-regulated during rabies virus infection in MmBr, suggesting their involvement in promotion of antiviral responses. The presence of CD14 and CD68 in MmBr suggested MmBr cells are microglia-like cells which play a key role in host defense against infections in the central nervous system (CNS). Thus the expression pattern of MmBr combined with the observed limitation of lyssavirus replication underpin a protective mechanism of the CNS controlling the lyssavirus infection. Overall, the established cell lines are important tools to analyze antiviral innate immunity in M. myotis against neurotropic virus infections and present a valuable tool for a

Donor genotype in the Interleukin-7 receptor α-chain predicts risk of graft-versus-host disease and cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation

DEFF Research Database (Denmark)

Kielsen, Katrine; Enevold, Christian; Heilmann, Carsten

2018-01-01

The efficacy of allogeneic hematopoietic stem cell transplantation (HSCT) is challenged by acute and chronic graft-versus-host disease (aGVHD and cGVHD) and viral infections due to long-lasting immunodeficiency. Interleukin-7 (IL-7) is a cytokine essential for de novo T cell generation in thymus.......1-3.8, P = 0.034) and with significantly increased risk of extensive cGVHD (HR = 2.0, 95% CI = 1.1-3.6, P = 0.025) after adjustment for potential risk factors. In addition, the TT genotype was associated with a higher risk of cytomegalovirus (CMV) infection post-transplant (HR = 2.4, 95% CI = 1.2-4.3, P.......7, 95% CI = 1.2-2.3, P = 0.0027) and increased treatment-related mortality (HR = 2.3, 95% CI = 1.3-4.0, P = 0.0047), but was not associated with the risk of relapse (P = 0.35). In conclusion, the IL-7Rα rs6897932 genotype of the donor is predictive of aGVHD and cGVHD, CMV infection, and mortality...

Severe hindrance of viral infection propagation in spatially extended hosts.

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José A Capitán

Full Text Available The production of large progeny numbers affected by high mutation rates is a ubiquitous strategy of viruses, as it promotes quick adaptation and survival to changing environments. However, this situation often ushers in an arms race between the virus and the host cells. In this paper we investigate in depth a model for the dynamics of a phenotypically heterogeneous population of viruses whose propagation is limited to two-dimensional geometries, and where host cells are able to develop defenses against infection. Our analytical and numerical analyses are developed in close connection to directed percolation models. In fact, we show that making the space explicit in the model, which in turn amounts to reducing viral mobility and hindering the infective ability of the virus, connects our work with similar dynamical models that lie in the universality class of directed percolation. In addition, we use the fact that our model is a multicomponent generalization of the Domany-Kinzel probabilistic cellular automaton to employ several techniques developed in the past in that context, such as the two-site approximation to the extinction transition line. Our aim is to better understand propagation of viral infections with mobility restrictions, e.g., in crops or in plant leaves, in order to inspire new strategies for effective viral control.

Genome-wide analysis of gene expression and protein secretion of Babesia canis during virulent infection identifies potential pathogenicity factors.

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Eichenberger, Ramon M; Ramakrishnan, Chandra; Russo, Giancarlo; Deplazes, Peter; Hehl, Adrian B

2017-06-13

Infections of dogs with virulent strains of Babesia canis are characterized by rapid onset and high mortality, comparable to complicated human malaria. As in other apicomplexan parasites, most Babesia virulence factors responsible for survival and pathogenicity are secreted to the host cell surface and beyond where they remodel and biochemically modify the infected cell interacting with host proteins in a very specific manner. Here, we investigated factors secreted by B. canis during acute infections in dogs and report on in silico predictions and experimental analysis of the parasite's exportome. As a backdrop, we generated a fully annotated B. canis genome sequence of a virulent Hungarian field isolate (strain BcH-CHIPZ) underpinned by extensive genome-wide RNA-seq analysis. We find evidence for conserved factors in apicomplexan hemoparasites involved in immune-evasion (e.g. VESA-protein family), proteins secreted across the iRBC membrane into the host bloodstream (e.g. SA- and Bc28 protein families), potential moonlighting proteins (e.g. profilin and histones), and uncharacterized antigens present during acute crisis in dogs. The combined data provides a first predicted and partially validated set of potential virulence factors exported during fatal infections, which can be exploited for urgently needed innovative intervention strategies aimed at facilitating diagnosis and management of canine babesiosis.

Staphylococcus aureus requires less virulence to establish an infection in diabetic hosts.

Science.gov (United States)

Tuchscherr, Lorena; Korpos, Èva; van de Vyver, Hélène; Findeisen, Clais; Kherkheulidze, Salome; Siegmund, Anke; Deinhardt-Emmer, Stefanie; Bach, Olaf; Rindert, Martin; Mellmann, Alexander; Sunderkötter, Cord; Peters, Georg; Sorokin, Lydia; Löffler, Bettina

2018-05-22

Staphylococcus aureus is the most frequent pathogen causing diabetic foot infections. Here, we investigated the degree of bacterial virulence required to establish invasive tissue infections in diabetic organisms. Staphylococcal isolates from diabetic and non-diabetic foot ulcers were tested for their virulence in in vitro functional assays of host cell invasion and cytotoxicity. Isolates from diabetes mellitus type I/II patients exhibited less virulence than isolates from non-diabetic patients, but were nevertheless able to establish severe infections. In some cases, non-invasive isolates were detected deep within diabetic wounds, even though the strains were non-pathogenic in cell culture models. Testing of defined isolates in murine footpad injection models revealed that both low- and high-virulent bacterial strains persisted in higher numbers in diabetic compared to non-diabetic hosts, suggesting that hyperglycemia favors bacterial survival. Additionally, the bacterial load was higher in NOD mice, which have a compromised immune system, compared to C57Bl/6 mice. Our results reveal that high as well as low-virulent staphylococcal strains are able to cause soft tissue infections and to persist in diabetic humans and mice, suggesting a reason for the frequent and endangering infections in patients with diabetes. Copyright © 2018 Elsevier GmbH. All rights reserved.

Cystic fibrosis-niche adaptation of Pseudomonas aeruginosa reduces virulence in multiple infection hosts.

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Nicola Ivan Lorè

Full Text Available The opportunistic pathogen Pseudomonas aeruginosa is able to thrive in diverse ecological niches and to cause serious human infection. P. aeruginosa environmental strains are producing various virulence factors that are required for establishing acute infections in several host organisms; however, the P. aeruginosa phenotypic variants favour long-term persistence in the cystic fibrosis (CF airways. Whether P. aeruginosa strains, which have adapted to the CF-niche, have lost their competitive fitness in the other environment remains to be investigated. In this paper, three P. aeruginosa clonal lineages, including early strains isolated at the onset of infection, and late strains, isolated after several years of chronic lung infection from patients with CF, were analysed in multi-host model systems of acute infection. P. aeruginosa early isolates caused lethality in the three non-mammalian hosts, namely Caenorhabditis elegans, Galleria mellonella, and Drosophila melanogaster, while late adapted clonal isolates were attenuated in acute virulence. When two different mouse genetic background strains, namely C57Bl/6NCrl and Balb/cAnNCrl, were used as acute infection models, early P. aeruginosa CF isolates were lethal, while late isolates exhibited reduced or abolished acute virulence. Severe histopathological lesions, including high leukocytes recruitment and bacterial load, were detected in the lungs of mice infected with P. aeruginosa CF early isolates, while late isolates were progressively cleared. In addition, systemic bacterial spread and invasion of epithelial cells, which were detected for P. aeruginosa CF early strains, were not observed with late strains. Our findings indicate that niche-specific selection in P. aeruginosa reduced its ability to cause acute infections across a broad range of hosts while maintaining the capacity for chronic infection in the CF host.

Combining genomic sequencing methods to explore viral diversity and reveal potential virus-host interactions

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Cheryl-Emiliane Tien Chow

2015-04-01

Full Text Available Viral diversity and virus-host interactions in oxygen-starved regions of the ocean, also known as oxygen minimum zones (OMZs, remain relatively unexplored. Microbial community metabolism in OMZs alters nutrient and energy flow through marine food webs, resulting in biological nitrogen loss and greenhouse gas production. Thus, viruses infecting OMZ microbes have the potential to modulate community metabolism with resulting feedback on ecosystem function. Here, we describe viral communities inhabiting oxic surface (10m and oxygen-starved basin (200m waters of Saanich Inlet, a seasonally anoxic fjord on the coast of Vancouver Island, British Columbia using viral metagenomics and complete viral fosmid sequencing on samples collected between April 2007 and April 2010. Of 6459 open reading frames (ORFs predicted across all 34 viral fosmids, 77.6% (n=5010 had no homology to reference viral genomes. These fosmids recruited a higher proportion of viral metagenomic sequences from Saanich Inlet than from nearby northeastern subarctic Pacific Ocean (Line P waters, indicating differences in the viral communities between coastal and open ocean locations. While functional annotations of fosmid ORFs were limited, recruitment to NCBI’s non-redundant ‘nr’ database and publicly available single-cell genomes identified putative viruses infecting marine thaumarchaeal and SUP05 proteobacteria to provide potential host linkages with relevance to coupled biogeochemical cycling processes in OMZ waters. Taken together, these results highlight the power of coupled analyses of multiple sequence data types, such as viral metagenomic and fosmid sequence data with prokaryotic single cell genomes, to chart viral diversity, elucidate genomic and ecological contexts for previously unclassifiable viral sequences, and identify novel host interactions in natural and engineered ecosystems.

The host cell sulfonation pathway contributes to retroviral infection at a step coincident with provirus establishment.

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James W Bruce

2008-11-01

Full Text Available The early steps of retrovirus replication leading up to provirus establishment are highly dependent on cellular processes and represent a time when the virus is particularly vulnerable to antivirals and host defense mechanisms. However, the roles played by cellular factors are only partially understood. To identify cellular processes that participate in these critical steps, we employed a high volume screening of insertionally mutagenized somatic cells using a murine leukemia virus (MLV vector. This approach identified a role for 3'-phosphoadenosine 5'-phosphosulfate synthase 1 (PAPSS1, one of two enzymes that synthesize PAPS, the high energy sulfate donor used in all sulfonation reactions catalyzed by cellular sulfotransferases. The role of the cellular sulfonation pathway was confirmed using chemical inhibitors of PAPS synthases and cellular sulfotransferases. The requirement for sulfonation was mapped to a stage during or shortly after MLV provirus establishment and influenced subsequent gene expression from the viral long terminal repeat (LTR promoter. Infection of cells by an HIV vector was also shown to be highly dependent on the cellular sulfonation pathway. These studies have uncovered a heretofore unknown regulatory step of retroviral replication, have defined a new biological function for sulfonation in nuclear gene expression, and provide a potentially valuable new target for HIV/AIDS therapy.

Using Proteomics to Understand How Leishmania Parasites Survive inside the Host and Establish Infection.

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Veras, Patrícia Sampaio Tavares; Bezerra de Menezes, Juliana Perrone

2016-08-19

Leishmania is a protozoan parasite that causes a wide range of different clinical manifestations in mammalian hosts. It is a major public health risk on different continents and represents one of the most important neglected diseases. Due to the high toxicity of the drugs currently used, and in the light of increasing drug resistance, there is a critical need to develop new drugs and vaccines to control Leishmania infection. Over the past few years, proteomics has become an important tool to understand the underlying biology of Leishmania parasites and host interaction. The large-scale study of proteins, both in parasites and within the host in response to infection, can accelerate the discovery of new therapeutic targets. By studying the proteomes of host cells and tissues infected with Leishmania, as well as changes in protein profiles among promastigotes and amastigotes, scientists hope to better understand the biology involved in the parasite survival and the host-parasite interaction. This review demonstrates the feasibility of proteomics as an approach to identify new proteins involved in Leishmania differentiation and intracellular survival.

Host-microbe interactions that shape the pathogenesis of Acinetobacter baumannii infection

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Mortensen, Brittany L.; Skaar, Eric P.

2013-01-01

Summary Acinetobacter baumannii is an opportunistic pathogen that has emerged as a prevalent source of nosocomial infections, most frequently causing ventilator-associated pneumonia. The emergence of pan-drug resistant strains magnifies the problem by reducing viable treatment options and effectively increasing the mortality rate associated with Acinetobacter infections. In light of this rising threat, research on A. baumannii epidemiology, antibiotic resistance, and pathogenesis is accelerating. The recent development of both in vitro and in vivo models has enabled studies probing the host-Acinetobacter interface. Bacterial genetic screens and comparative genomic studies have led to the identification of several A. baumannii virulence factors. Additionally, investigations into host defense mechanisms using animal models or cell culture have provided insight into the innate immune response to infection. This review highlights some of the key attributes of A. baumannii virulence with an emphasis on bacterial interactions with the innate immune system. PMID:22640368

A MAM7 peptide-based inhibitor of Staphylococcus aureus adhesion does not interfere with in vitro host cell function.

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Catherine Alice Hawley

Full Text Available Adhesion inhibitors that block the attachment of pathogens to host tissues may be used synergistically with or as an alternative to antibiotics. The wide-spread bacterial adhesin Multivalent Adhesion Molecule (MAM 7 has recently emerged as a candidate molecule for a broad-spectrum adhesion inhibitor which may be used to prevent bacterial colonization of wounds. Here we have tested if the antibacterial properties of a MAM-based inhibitor could be used to competitively inhibit adhesion of methicillin-resistant Staphylococcus aureus (MRSA to host cells. Additionally, we analyzed its effect on host cellular functions linked to the host receptor fibronectin, such as migration, adhesion and matrix formation in vitro, to evaluate potential side effects prior to advancing our studies to in vivo infection models. As controls, we used inhibitors based on well-characterized bacterial adhesin-derived peptides from F1 and FnBPA, which are known to affect host cellular functions. Inhibitors based on F1 or FnBPA blocked MRSA attachment but at the same time abrogated important cellular functions. A MAM7-based inhibitor did not interfere with host cell function while showing good efficacy against MRSA adhesion in a tissue culture model. These observations provide a possible candidate for a bacterial adhesion inhibitor that does not cause adverse effects on host cells while preventing bacterial infection.

Murid herpesvirus-4 exploits dendritic cells to infect B cells.

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Miguel Gaspar

2011-11-01

Full Text Available Dendritic cells (DCs play a central role in initiating immune responses. Some persistent viruses infect DCs and can disrupt their functions in vitro. However, these viruses remain strongly immunogenic in vivo. Thus what role DC infection plays in the pathogenesis of persistent infections is unclear. Here we show that a persistent, B cell-tropic gamma-herpesvirus, Murid Herpesvirus-4 (MuHV-4, infects DCs early after host entry, before it establishes a substantial infection of B cells. DC-specific virus marking by cre-lox recombination revealed that a significant fraction of the virus latent in B cells had passed through a DC, and a virus attenuated for replication in DCs was impaired in B cell colonization. In vitro MuHV-4 dramatically altered the DC cytoskeleton, suggesting that it manipulates DC migration and shape in order to spread. MuHV-4 therefore uses DCs to colonize B cells.

Quantitative proteomics of Spodoptera frugiperda cells during growth and baculovirus infection.

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Nuno Carinhas

Full Text Available Baculovirus infection of Spodoptera frugiperda cells is a system of choice to produce a range of recombinant proteins, vaccines and, potentially, gene therapy vectors. While baculovirus genomes are well characterized, the genome of S. frugiperda is not sequenced and the virus-host molecular interplay is sparsely known. Herein, we describe the application of stable isotope labeling by amino acids in cell culture (SILAC to obtain the first comparative proteome quantitation of S. frugiperda cells during growth and early baculovirus infection. The proteome coverage was maximized by compiling a search database with protein annotations from insect species. Of interest were differentially proteins related to energy metabolism, endoplasmic reticulum and oxidative stress, yet not investigated in the scope of baculovirus infection. Further, the reduced expression of key viral-encoded proteins early in the infection cycle is suggested to be related with decreased viral replication at high cell density culture. These findings have implications for virological research and improvement of baculovirus-based bioprocesses.

Meta-analyses of the proportion of Japanese encephalitis virus infection in vectors and vertebrate hosts.

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Oliveira, Ana R S; Cohnstaedt, Lee W; Strathe, Erin; Hernández, Luciana Etcheverry; McVey, D Scott; Piaggio, José; Cernicchiaro, Natalia

2017-09-07

Japanese encephalitis (JE) is a zoonosis in Southeast Asia vectored by mosquitoes infected with the Japanese encephalitis virus (JEV). Japanese encephalitis is considered an emerging exotic infectious disease with potential for introduction in currently JEV-free countries. Pigs and ardeid birds are reservoir hosts and play a major role on the transmission dynamics of the disease. The objective of the study was to quantitatively summarize the proportion of JEV infection in vectors and vertebrate hosts from data pertaining to observational studies obtained in a systematic review of the literature on vector and host competence for JEV, using meta-analyses. Data gathered in this study pertained to three outcomes: proportion of JEV infection in vectors, proportion of JEV infection in vertebrate hosts, and minimum infection rate (MIR) in vectors. Random-effects subgroup meta-analysis models were fitted by species (mosquito or vertebrate host species) to estimate pooled summary measures, as well as to compute the variance between studies. Meta-regression models were fitted to assess the association between different predictors and the outcomes of interest and to identify sources of heterogeneity among studies. Predictors included in all models were mosquito/vertebrate host species, diagnostic methods, mosquito capture methods, season, country/region, age category, and number of mosquitos per pool. Mosquito species, diagnostic method, country, and capture method represented important sources of heterogeneity associated with the proportion of JEV infection; host species and region were considered sources of heterogeneity associated with the proportion of JEV infection in hosts; and diagnostic and mosquito capture methods were deemed important contributors of heterogeneity for the MIR outcome. Our findings provide reference pooled summary estimates of vector competence for JEV for some mosquito species, as well as of sources of variability for these outcomes. Moreover, this

Apoptosis in HEp-2 cells infected with Ureaplasma diversum.

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Amorim, Aline Teixeira; Marques, Lucas Miranda; Santos, Angelita Maria Oliveira Gusmão; Martins, Hellen Braga; Barbosa, Maysa Santos; Rezende, Izadora Souza; Andrade, Ewerton Ferraz; Campos, Guilherme Barreto; Lobão, Tássia Neves; Cortez, Beatriz Araujo; Monezi, Telma Alvez; Machado-Santelli, Glaucia Maria; Timenetsky, Jorge

2014-09-04

Bacterial pathogens have many strategies for infecting and persisting in host cells. Adhesion, invasion and intracellular life are important features in the biology of mollicutes. The intracellular location of Ureaplasma diversum may trigger disturbances in the host cell. This includes activation or inhibition of pro and anti-apoptotic factors, which facilitate the development of host damage. The aim of the present study was to associate U. diversum infection in HEp-2 cells and apoptosis induction. Cells were infected for 72hs with four U. diversum clinical isolates and an ATCC strain. The U. diversum invasion was analyzed by Confocal Laser Scanning Microscopy and gentamicin invasion assay. The apoptosis was evaluated using pro-apoptotic and anti-apoptotic gene expression, and FITC Annexin V/Dead Cell Apoptosis Kit. The number of internalized ureaplasma in HEp-2 cells increased significantly throughout the infection. The flow cytometry analysis with fluorochromes to detect membrane depolarization and gene expression for caspase 2, 3 and 9 increased in infected cells after 24 hours. However, after 72 hours a considerable decrease of apoptotic cells was observed. The data suggests that apoptosis may be initially induced by some isolates in association with HEp-2 cells, but over time, there was no evidence of apoptosis in the presence of ureaplasma and HEp-2 cells. The initial increase and then decrease in apoptosis could be related to bacterial pathogen-associated molecular pattern (PAMPS). Moreover, the isolates of U. diversum presented differences in the studied parameters for apoptosis. It was also observed that the amount of microorganisms was not proportional to the induction of apoptosis in HEp-2 cells.

Impact of the Respiratory Microbiome on Host Responses to Respiratory Viral Infection

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Maxime Pichon

2017-11-01

Full Text Available Viruses are responsible for most of both upper and lower acute respiratory infections (ARIs. The microbiome—the ecological community of microorganisms sharing the body space, which has gained considerable interest over the last decade—is modified in health and disease states. Even if most of these disturbances have been previously described in relation to chronic disorders of the gastrointestinal microbiome, after a short reminder of microbiome characteristics and methods of characterization, this review will describe the impact of the microbiome (mainly respiratory on host responses to viral ARIs. The microbiome has a direct environmental impact on the host cells but also an indirect impact on the immune system, by enhancing innate or adaptive immune responses. In microbial infections, especially in viral infections, these dramatic modifications could lead to a dramatic impact responsible for severe clinical outcomes. Studies focusing on the microbiome associated with transcriptomic analyses of the host response and deep characterization of the pathogen would lead to a better understanding of viral pathogenesis and open avenues for biomarker development and innovative therapeutics.

Fungal cell gigantism during mammalian infection.

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Oscar Zaragoza

2010-06-01

Full Text Available The interaction between fungal pathogens with the host frequently results in morphological changes, such as hyphae formation. The encapsulated pathogenic fungus Cryptococcus neoformans is not considered a dimorphic fungus, and is predominantly found in host tissues as round yeast cells. However, there is a specific morphological change associated with cryptococcal infection that involves an increase in capsule volume. We now report another morphological change whereby gigantic cells are formed in tissue. The paper reports the phenotypic characterization of giant cells isolated from infected mice and the cellular changes associated with giant cell formation. C. neoformans infection in mice resulted in the appearance of giant cells with cell bodies up to 30 microm in diameter and capsules resistant to stripping with gamma-radiation and organic solvents. The proportion of giant cells ranged from 10 to 80% of the total lung fungal burden, depending on infection time, individual mice, and correlated with the type of immune response. When placed on agar, giant cells budded to produce small daughter cells that traversed the capsule of the mother cell at the speed of 20-50 m/h. Giant cells with dimensions that approximated those in vivo were observed in vitro after prolonged culture in minimal media, and were the oldest in the culture, suggesting that giant cell formation is an aging-dependent phenomenon. Giant cells recovered from mice displayed polyploidy, suggesting a mechanism by which gigantism results from cell cycle progression without cell fission. Giant cell formation was dependent on cAMP, but not on Ras1. Real-time imaging showed that giant cells were engaged, but not engulfed by phagocytic cells. We describe a remarkable new strategy for C. neoformans to evade the immune response by enlarging cell size, and suggest that gigantism results from replication without fission, a phenomenon that may also occur with other fungal pathogens.

Fungal cell gigantism during mammalian infection.

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Zaragoza, Oscar; García-Rodas, Rocío; Nosanchuk, Joshua D; Cuenca-Estrella, Manuel; Rodríguez-Tudela, Juan Luis; Casadevall, Arturo

2010-06-17

The interaction between fungal pathogens with the host frequently results in morphological changes, such as hyphae formation. The encapsulated pathogenic fungus Cryptococcus neoformans is not considered a dimorphic fungus, and is predominantly found in host tissues as round yeast cells. However, there is a specific morphological change associated with cryptococcal infection that involves an increase in capsule volume. We now report another morphological change whereby gigantic cells are formed in tissue. The paper reports the phenotypic characterization of giant cells isolated from infected mice and the cellular changes associated with giant cell formation. C. neoformans infection in mice resulted in the appearance of giant cells with cell bodies up to 30 microm in diameter and capsules resistant to stripping with gamma-radiation and organic solvents. The proportion of giant cells ranged from 10 to 80% of the total lung fungal burden, depending on infection time, individual mice, and correlated with the type of immune response. When placed on agar, giant cells budded to produce small daughter cells that traversed the capsule of the mother cell at the speed of 20-50 m/h. Giant cells with dimensions that approximated those in vivo were observed in vitro after prolonged culture in minimal media, and were the oldest in the culture, suggesting that giant cell formation is an aging-dependent phenomenon. Giant cells recovered from mice displayed polyploidy, suggesting a mechanism by which gigantism results from cell cycle progression without cell fission. Giant cell formation was dependent on cAMP, but not on Ras1. Real-time imaging showed that giant cells were engaged, but not engulfed by phagocytic cells. We describe a remarkable new strategy for C. neoformans to evade the immune response by enlarging cell size, and suggest that gigantism results from replication without fission, a phenomenon that may also occur with other fungal pathogens.

Host epithelial cell invasion by Campylobacter jejuni: trigger or zipper mechanism?

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Tadhg eÓ Cróinín

2012-03-01

Full Text Available Campylobacter jejuni, a spiral-shaped Gram-negative pathogen, is a highly frequent cause of gastrointestinal foodborne illness in humans worldwide. Clinical outcome of C. jejuni infections ranges from mild to severe diarrheal disease, and some other complications including reactive arthritis and Guillain–Barré syndrome. This review article highlights various C. jejuni pathogenicity factors, host cell determinants and proposed signaling mechanisms involved in human host cell invasion and their potential role in the development of C. jejuni-mediated disease. A model is presented which outlines the various important interactions of C. jejuni with the intestinal epithelium, and we discuss the pro’s and con’s for the zipper over the trigger mechanism of invasion. Future work should clarify the contradictory role of some previously identified factors, and should identify and characterize novel virulence determinants, which are crucial to provide fresh insights into the diversity of strategies employed by this pathogen to cause disease.

FRET imaging of hemoglobin concentration in Plasmodium falciparum-infected red cells.

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Alessandro Esposito

Full Text Available During its intraerythrocytic asexual reproduction cycle Plasmodium falciparum consumes up to 80% of the host cell hemoglobin, in large excess over its metabolic needs. A model of the homeostasis of falciparum-infected red blood cells suggested an explanation based on the need to reduce the colloid-osmotic pressure within the host cell to prevent its premature lysis. Critical for this hypothesis was that the hemoglobin concentration within the host cell be progressively reduced from the trophozoite stage onwards.The experiments reported here were designed to test this hypothesis by direct measurements of the hemoglobin concentration in live, infected red cells. We developed a novel, non-invasive method to quantify the hemoglobin concentration in single cells, based on Förster resonance energy transfer between hemoglobin molecules and the fluorophore calcein. Fluorescence lifetime imaging allowed the quantitative mapping of the hemoglobin concentration within the cells. The average fluorescence lifetimes of uninfected cohorts was 270+/-30 ps (mean+/-SD; N = 45. In the cytoplasm of infected cells the fluorescence lifetime of calcein ranged from 290+/-20 ps for cells with ring stage parasites to 590+/-13 ps and 1050+/-60 ps for cells with young trophozoites and late stage trophozoite/early schizonts, respectively. This was equivalent to reductions in hemoglobin concentration spanning the range from 7.3 to 2.3 mM, in line with the model predictions. An unexpected ancillary finding was the existence of a microdomain under the host cell membrane with reduced calcein quenching by hemoglobin in cells with mature trophozoite stage parasites.The results support the predictions of the colloid-osmotic hypothesis and provide a better understanding of the homeostasis of malaria-infected red cells. In addition, they revealed the existence of a distinct peripheral microdomain in the host cell with limited access to hemoglobin molecules indicating the

Multiple factors and processes involved in host cell killing by bacteriophage Mu: characterization and mapping.

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Waggoner, B T; Marrs, C F; Howe, M M; Pato, M L

1984-07-15

The regions of bacteriophage Mu involved in host cell killing were determined by infection of a lambda-immune host with 12 lambda pMu-transducing phages carrying different amounts of Mu DNA beginning at the left end. Infecting lambda pMu phages containing 5.0 (+/- 0.2) kb or less of the left end of Mu DNA did not kill the lambda-immune host, whereas lambda pMu containing 5.1 kb did kill, thus locating the right end of the kil gene between approximately 5.0 and 5.1 kb. For the Kil+ phages the extent of killing increased as the multiplicity of infection (m.o.i.) increased. In addition, killing was also affected by the presence of at least two other regions of Mu DNA: one, located between 5.1 and 5.8 kb, decreased the extent of killing; the other, located between 6.3 and 7.9 kb, greatly increased host cell killing. Killing was also assayed after lambda pMu infection of a lambda-immune host carrying a mini-Mu deleted for most of the B gene and the middle region of Mu DNA. Complementation of mini-Mu replication by infecting B+ lambda pMu phages resulted in killing of the lambda-immune, mini-Mu-containing host, regardless of the presence or absence of the Mu kil gene. The extent of host cell killing increased as the m.o.i. of the infecting lambda pMu increased, and was further enhanced by both the presence of the kil gene and the region located between 6.3 and 7.9 kb. These distinct processes of kil-mediated killing in the absence of replication and non-kil-mediated killing in the presence of replication were also observed after induction of replication-deficient and kil mutant prophages, respectively.

Cell death by pyroptosis drives CD4 T-cell depletion in HIV-1 infection

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Doitsh, Gilad; Galloway, Nicole L. K.; Geng, Xin; Yang, Zhiyuan; Monroe, Kathryn M.; Zepeda, Orlando; Hunt, Peter W.; Hatano, Hiroyu; Sowinski, Stefanie; Muñoz-Arias, Isa; Greene, Warner C.

2014-01-01

The pathway causing CD4 T-cell death in HIV-infected hosts remains poorly understood although apoptosis has been proposed as a key mechanism. We now show that caspase-3-mediated apoptosis accounts for the death of only a small fraction of CD4 T cells corresponding to those that are both activated and productively infected. The remaining over 95% of quiescent lymphoid CD4 T cells die by caspase-1-mediated pyroptosis triggered by abortive viral infection. Pyroptosis corresponds to an intensely inflammatory form of programmed cell death in which cytoplasmic contents and pro-inflammatory cytokines, including IL-1β, are released. This death pathway thus links the two signature events in HIV infection--CD4 T-cell depletion and chronic inflammation--and creates a pathogenic vicious cycle in which dying CD4 T cells release inflammatory signals that attract more cells to die. This cycle can be broken by caspase 1 inhibitors shown to be safe in humans, raising the possibility of a new class of `anti-AIDS' therapeutics targeting the host rather than the virus.

The Typhoid Toxin Promotes Host Survival and the Establishment of a Persistent Asymptomatic Infection

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Del Bel Belluz, Lisa; Guidi, Riccardo; Pateras, Ioannis S.

2016-01-01

Bacterial genotoxins, produced by several Gram-negative bacteria, induce DNA damage in the target cells. While the responses induced in the host cells have been extensively studied in vitro, the role of these effectors during the course of infection remains poorly characterized. To address this i...

The relationship between host lifespan and pathogen reservoir potential: an analysis in the system Arabidopsis thaliana--cucumber mosaic virus.

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Jean Michel Hily

2014-11-01

Full Text Available Identification of the determinants of pathogen reservoir potential is central to understand disease emergence. It has been proposed that host lifespan is one such determinant: short-lived hosts will invest less in costly defenses against pathogens, so that they will be more susceptible to infection, more competent as sources of infection and/or will sustain larger vector populations, thus being effective reservoirs for the infection of long-lived hosts. This hypothesis is sustained by analyses of different hosts of multihost pathogens, but not of different genotypes of the same host species. Here we examined this hypothesis by comparing two genotypes of the plant Arabidopsis thaliana that differ largely both in life-span and in tolerance to its natural pathogen Cucumber mosaic virus (CMV. Experiments with the aphid vector Myzus persicae showed that both genotypes were similarly competent as sources for virus transmission, but the short-lived genotype was more susceptible to infection and was able to sustain larger vector populations. To explore how differences in defense against CMV and its vector relate to reservoir potential, we developed a model that was run for a set of experimentally-determined parameters, and for a realistic range of host plant and vector population densities. Model simulations showed that the less efficient defenses of the short-lived genotype resulted in higher reservoir potential, which in heterogeneous host populations may be balanced by the longer infectious period of the long-lived genotype. This balance was modulated by the demography of both host and vector populations, and by the genetic composition of the host population. Thus, within-species genetic diversity for lifespan and defenses against pathogens will result in polymorphisms for pathogen reservoir potential, which will condition within-population infection dynamics. These results are relevant for a better understanding of host-pathogen co-evolution, and of

Chlamydia trachomatis infections and subfertility: opportunities to translate host pathogen genomic data into public health.

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Lal, J A; Malogajski, J; Verweij, S P; de Boer, P; Ambrosino, E; Brand, A; Ouburg, S; Morré, S A

2013-01-01

Chlamydia trachomatis (CT) infections in women can result in tubal pathology (TP). Worldwide 10-15% of all couples are subfertile, meaning they did not get pregnant after 1 year. Part of the routine subfertility diagnostics is the Chlamydia Antibody Test (CAT) to decide for laparoscopy or not in order to diagnose TP. The CAT positive and negative predictive value is such that many unneeded laparoscopies are done and many TP cases are missed. Addition of host genetic markers related to infection susceptibility and severity could potentially improve the clinical management of couples who suffer from subfertility. In the present study, the potential translational and clinical value of adding diagnostic host genetic marker profiles on the basis of infection and inflammation to the current clinical management of subfertility was investigated. This review provides an overview of the current state of the art of host genetic markers in relation to CT infection, proposes a new clinical diagnostic approach, and investigates how the Learning-Adapting-Leveling model (LAL, a public health genomic (PHG) model) can be of value and provide insight to see whether these host genetic markers can be translated into public health. This review shows that the preliminary basis of adding host genetic marker profiles to the current diagnostic procedures of subfertility is present but has to be further developed before implementation into health care can be achieved. CT infection is an example in the field of PHG with potential diagnostic to be taken up in the future in the field of subfertility diagnosis with a time line for integration to be dependent on enhanced participation of many stakeholders in the field of PHG which could be advanced through the LAL model. Copyright © 2013 S. Karger AG, Basel.

Host cell reactivation in mammalian cells

International Nuclear Information System (INIS)

Lytle, C.D.; Benane, S.G.; Stafford, J.E.

1976-01-01

The survival of UV-irradiated herpes simplex virus was determined in cultured Potoroo (a marsupial) and human cells under lighting conditions which promoted photereactivation. Photoreactivation was readily demonstrated for herpes virus in two lines of Potoroo cells with dose reduction factors of 0.7 to 0.8 for ovary cells and 0.5 to 0.7 for kidney cells. Light from Blacklite (near UV) lamps was more effective than from Daylight (mostly visible) lamps, suggesting that near UV radiation was more effecient for photoreactivation in Potoroo cells. The quantitative and qualitative aspects of this photoreactivation were similar to those reported for a similar virus infecting chick embryo cells. UV-survival curves of herpes virus in Potoroo cells indicated a high level of 'dark' host cell reactivation. No photoreactivation was found for UV-irradiated vaccinia virus in Potoroo cells. A similar photoreactivation study was done using special control lighting (lambda>600 nm) and human cells with normal repair and with cells deficient in excision repair (XP). No photoreactivation was found for UV-irradiated herpes virus in either human cell with either Blacklite or Daylight lamps as the sources of photoreactivating light. This result contrasts with a report of photoreactivation for a herpes virus in the same XP cells using incandescent lamps. (author)

Cell wall composition profiling of parasitic giant dodder (Cuscuta reflexa) and its hosts: a priori differences and induced changes.

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Johnsen, Hanne R; Striberny, Bernd; Olsen, Stian; Vidal-Melgosa, Silvia; Fangel, Jonatan U; Willats, William G T; Rose, Jocelyn K C; Krause, Kirsten

2015-08-01

Host plant penetration is the gateway to survival for holoparasitic Cuscuta and requires host cell wall degradation. Compositional differences of cell walls may explain why some hosts are amenable to such degradation while others can resist infection. Antibody-based techniques for comprehensive profiling of cell wall epitopes and cell wall-modifying enzymes were applied to several susceptible hosts and a resistant host of Cuscuta reflexa and to the parasite itself. Infected tissue of Pelargonium zonale contained high concentrations of de-esterified homogalacturonans in the cell walls, particularly adjacent to the parasite's haustoria. High pectinolytic activity in haustorial extracts and high expression levels of pectate lyase genes suggest that the parasite contributes directly to wall remodeling. Mannan and xylan concentrations were low in P. zonale and in five susceptible tomato introgression lines, but high in the resistant Solanum lycopersicum cv M82, and in C. reflexa itself. Knowledge of the composition of resistant host cell walls and the parasite's own cell walls is useful in developing strategies to prevent infection by parasitic plants. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Diversity of susceptible hosts in canine distemper virus infection: a systematic review and data synthesis.

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Martinez-Gutierrez, Marlen; Ruiz-Saenz, Julian

2016-05-12

Canine distemper virus (CDV) is the etiological agent of one of the most infectious diseases of domestic dogs, also known as a highly prevalent viral infectious disease of carnivores and posing a conservation threat to endangered species around the world. To get a better panorama of CDV infection in different Orders, a retrospective and documental systematic review of the role of CDV in different non-dog hosts was conducted. The bibliographical data were collected from MedLine/PubMed and Scopus databases. Data related to Order, Family, Genus and Species of the infected animals, the presence or absence of clinical signs, mortality, serological, molecular or antigenic confirmation of CDV infection, geographic location, were collected and summarized. Two hundred seventeen scientific articles were considered eligible which includes reports of serological evaluation, and antigenic or genomic confirmation of CDV infection in non-dog hosts. CDV infects naturally and experimentally different members of the Orders Carnivora (in 12 Families), Rodentia (four Families), Primates (two Families), Artiodactyla (three Families) and Proboscidea (one Family). The Order Carnivora (excluding domestic dogs) accounts for the vast majority (87.5%) of the records. Clinical disease associated with CDV infection was reported in 51.8% of the records and serological evidence of CDV infection in apparently healthy animals was found in 49.5% of the records. High mortality rate was showed in some of the recorded infections in Orders different to Carnivora. In non-dog hosts, CDV has been reported all continents with the exception of Australasia and in 43 different countries. The results of this systematic review demonstrate that CDV is able to infect a very wide range of host species from many different Orders and emphasizes the potential threat of infection for endangered wild species as well as raising concerns about potential zoonotic threats following the cessation of large-scale measles

Inhibition of Wnt Signaling Pathways Impairs Chlamydia trachomatis Infection in Endometrial Epithelial Cells.

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Kintner, Jennifer; Moore, Cheryl G; Whittimore, Judy D; Butler, Megan; Hall, Jennifer V

2017-01-01

Chlamydia trachomatis infections represent the predominant cause of bacterial sexually transmitted infections. As an obligate intracellular bacterium, C. trachomatis is dependent on the host cell for survival, propagation, and transmission. Thus, factors that affect the host cell, including nutrition, cell cycle, and environmental signals, have the potential to impact chlamydial development. Previous studies have demonstrated that activation of Wnt/β-catenin signaling benefits C. trachomatis infections in fallopian tube epithelia. In cervical epithelial cells chlamydiae sequester β-catenin within the inclusion. These data indicate that chlamydiae interact with the Wnt signaling pathway in both the upper and lower female genital tract (FGT). However, hormonal activation of canonical and non-canonical Wnt signaling pathways is an essential component of cyclic remodeling in another prominent area of the FGT, the endometrium. Given this information, we hypothesized that Wnt signaling would impact chlamydial infection in endometrial epithelial cells. To investigate this hypothesis, we analyzed the effect of Wnt inhibition on chlamydial inclusion development and elementary body (EB) production in two endometrial cell lines, Ishikawa (IK) and Hec-1B, in nonpolarized cell culture and in a polarized endometrial epithelial (IK)/stromal (SHT-290) cell co-culture model. Inhibition of Wnt by the small molecule inhibitor (IWP2) significantly decreased inclusion size in IK and IK/SHT-290 cultures ( p Wnt inhibition caused chlamydiae to become aberrant in morphology. EB formation was also impaired in IK, Hec-1B and IK/SHT-290 cultures regardless of whether Wnt inhibition occurred throughout, in the middle (24 hpi) or late (36 hpi) during the development cycle. Overall, these data lead us to conclude that Wnt signaling in the endometrium is a key host pathway for the proper development of C. trachomatis .

Bacteria Facilitate Enteric Virus Co-infection of Mammalian Cells and Promote Genetic Recombination.

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Erickson, Andrea K; Jesudhasan, Palmy R; Mayer, Melinda J; Narbad, Arjan; Winter, Sebastian E; Pfeiffer, Julie K

2018-01-10

RNA viruses exist in genetically diverse populations due to high levels of mutations, many of which reduce viral fitness. Interestingly, intestinal bacteria can promote infection of several mammalian enteric RNA viruses, but the mechanisms and consequences are unclear. We screened a panel of 41 bacterial strains as a platform to determine how different bacteria impact infection of poliovirus, a model enteric virus. Most bacterial strains, including those extracted from cecal contents of mice, bound poliovirus, with each bacterium binding multiple virions. Certain bacterial strains increased viral co-infection of mammalian cells even at a low virus-to-host cell ratio. Bacteria-mediated viral co-infection correlated with bacterial adherence to cells. Importantly, bacterial strains that induced viral co-infection facilitated genetic recombination between two different viruses, thereby removing deleterious mutations and restoring viral fitness. Thus, bacteria-virus interactions may increase viral fitness through viral recombination at initial sites of infection, potentially limiting abortive infections. Copyright © 2017 Elsevier Inc. All rights reserved.

The chlamydial periplasmic stress response serine protease cHtrA is secreted into host cell cytosol

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Flores Rhonda

2011-04-01

Full Text Available Abstract Background The periplasmic High Temperature Requirement protein A (HtrA plays important roles in bacterial protein folding and stress responses. However, the role of chlamydial HtrA (cHtrA in chlamydial pathogenesis is not clear. Results The cHtrA was detected both inside and outside the chlamydial inclusions. The detection was specific since both polyclonal and monoclonal anti-cHtrA antibodies revealed similar intracellular labeling patterns that were only removed by absorption with cHtrA but not control fusion proteins. In a Western blot assay, the anti-cHtrA antibodies detected the endogenous cHtrA in Chlamydia-infected cells without cross-reacting with any other chlamydial or host cell antigens. Fractionation of the infected cells revealed cHtrA in the host cell cytosol fraction. The periplasmic cHtrA protein appeared to be actively secreted into host cell cytosol since no other chlamydial periplasmic proteins were detected in the host cell cytoplasm. Most chlamydial species secreted cHtrA into host cell cytosol and the secretion was not inhibitable by a type III secretion inhibitor. Conclusion Since it is hypothesized that chlamydial organisms possess a proteolysis strategy to manipulate host cell signaling pathways, secretion of the serine protease cHtrA into host cell cytosol suggests that the periplasmic cHtrA may also play an important role in chlamydial interactions with host cells.

Brucella abortus choloylglycine hydrolase affects cell envelope composition and host cell internalization.

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María Inés Marchesini

Full Text Available Choloylglycine hydrolase (CGH, E.C. 3.5.1.24 is a conjugated bile salt hydrolase that catalyses the hydrolysis of the amide bond in conjugated bile acids. Bile salt hydrolases are expressed by gastrointestinal bacteria, and they presumably decrease the toxicity of host's conjugated bile salts. Brucella species are the causative agents of brucellosis, a disease affecting livestock and humans. CGH confers Brucella the ability to deconjugate and resist the antimicrobial action of bile salts, contributing to the establishment of a successful infection through the oral route in mice. Additionally, cgh-deletion mutant was also attenuated in intraperitoneally inoculated mice, which suggests that CGH may play a role during systemic infection other than hydrolyzing conjugated bile acids. To understand the role CGH plays in B. abortus virulence, we infected phagocytic and epithelial cells with a cgh-deletion mutant (Δcgh and found that it is defective in the internalization process. This defect along with the increased resistance of Δcgh to the antimicrobial action of polymyxin B, prompted an analysis of the cell envelope of this mutant. Two-dimensional electrophoretic profiles of Δcgh cell envelope-associated proteins showed an altered expression of Omp2b and different members of the Omp25/31 family. These results were confirmed by Western blot analysis with monoclonal antibodies. Altogether, the results indicate that Brucella CGH not only participates in deconjugation of bile salts but also affects overall membrane composition and host cell internalization.

Staphylococcus aureus produces membrane-derived vesicles that induce host cell death.

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Mamata Gurung

Full Text Available Gram-negative bacteria produce outer membrane vesicles that play a role in the delivery of virulence factors to host cells. However, little is known about the membrane-derived vesicles (MVs produced by gram-positive bacteria. The present study examined the production of MVs from Staphylococcus aureus and investigated the delivery of MVs to host cells and subsequent cytotoxicity. Four S. aureus strains tested, two type strains and two clinical isolates, produced spherical nanovesicles during in vitro culture. MVs were also produced during in vivo infection of a clinical S. aureus isolate in a mouse pneumonia model. Proteomic analysis showed that 143 different proteins were identified in the S. aureus-derived MVs. S. aureus MVs were interacted with the plasma membrane of host cells via a cholesterol-rich membrane microdomain and then delivered their component protein A to host cells within 30 min. Intact S. aureus MVs induced apoptosis of HEp-2 cells in a dose-dependent manner, whereas lysed MVs neither delivered their component into the cytosol of host cells nor induced cytotoxicity. In conclusion, this study is the first report that S. aureus MVs are an important vehicle for delivery of bacterial effector molecules to host cells.

Direct identification of the Meloidogyne incognita secretome reveals proteins with host cell reprogramming potential.

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Stéphane Bellafiore

2008-10-01

Full Text Available The root knot nematode, Meloidogyne incognita, is an obligate parasite that causes significant damage to a broad range of host plants. Infection is associated with secretion of proteins surrounded by proliferating cells. Many parasites are known to secrete effectors that interfere with plant innate immunity, enabling infection to occur; they can also release pathogen-associated molecular patterns (PAMPs, e.g., flagellin that trigger basal immunity through the nematode stylet into the plant cell. This leads to suppression of innate immunity and reprogramming of plant cells to form a feeding structure containing multinucleate giant cells. Effectors have generally been discovered using genetics or bioinformatics, but M. incognita is non-sexual and its genome sequence has not yet been reported. To partially overcome these limitations, we have used mass spectrometry to directly identify 486 proteins secreted by M. incognita. These proteins contain at least segmental sequence identity to those found in our 3 reference databases (published nematode proteins; unpublished M. incognita ESTs; published plant proteins. Several secreted proteins are homologous to plant proteins, which they may mimic, and they contain domains that suggest known effector functions (e.g., regulating the plant cell cycle or growth. Others have regulatory domains that could reprogram cells. Using in situ hybridization we observed that most secreted proteins were produced by the subventral glands, but we found that phasmids also secreted proteins. We annotated the functions of the secreted proteins and classified them according to roles they may play in the development of root knot disease. Our results show that parasite secretomes can be partially characterized without cognate genomic DNA sequence. We observed that the M. incognita secretome overlaps the reported secretome of mammalian parasitic nematodes (e.g., Brugia malayi, suggesting a common parasitic behavior and a possible

Cytoarchitecture of Zika virus infection in human neuroblastoma and Aedes albopictus cell lines

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Offerdahl, Danielle K.; Dorward, David W.; Hansen, Bryan T.; Bloom, Marshall E.

2017-01-01

The Zika virus (ZIKV) pandemic is a global concern due to its role in the development of congenital anomalies of the central nervous system. This mosquito-borne flavivirus alternates between mammalian and mosquito hosts, but information about the biogenesis of ZIKV is limited. Using a human neuroblastoma cell line (SK-N-SH) and an Aedes albopictus mosquito cell line (C6/36), we characterized ZIKV infection by immunofluorescence, transmission electron microscopy (TEM), and electron tomography (ET) to better understand infection in these disparate host cells. ZIKV replicated well in both cell lines, but infected SK-N-SH cells suffered a lytic crisis. Flaviviruses scavenge host cell membranes to serve as replication platforms and ZIKV showed the hallmarks of this process. Via TEM, we identified virus particles and 60–100 nm spherular vesicles. ET revealed these vesicular replication compartments contain smaller 20–30 nm spherular structures. Our studies indicate that SK-N-SH and C6/36 cells are relevant models for viral cytoarchitecture study. - Highlights: •First electron tomography of Zika virus cytoarchitecture. •Comparison of Zika virus infection in human neuroblastoma and mosquito cells. •Ultrastructure of Zika virus infection in human neuroblastoma and mosquito cells.

Cytoarchitecture of Zika virus infection in human neuroblastoma and Aedes albopictus cell lines

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Offerdahl, Danielle K. [Laboratory of Virology, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT (United States); Dorward, David W.; Hansen, Bryan T. [Microscopy Unit, Research Technology Branch, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT (United States); Bloom, Marshall E., E-mail: mbloom@nih.gov [Laboratory of Virology, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT (United States)

2017-01-15

The Zika virus (ZIKV) pandemic is a global concern due to its role in the development of congenital anomalies of the central nervous system. This mosquito-borne flavivirus alternates between mammalian and mosquito hosts, but information about the biogenesis of ZIKV is limited. Using a human neuroblastoma cell line (SK-N-SH) and an Aedes albopictus mosquito cell line (C6/36), we characterized ZIKV infection by immunofluorescence, transmission electron microscopy (TEM), and electron tomography (ET) to better understand infection in these disparate host cells. ZIKV replicated well in both cell lines, but infected SK-N-SH cells suffered a lytic crisis. Flaviviruses scavenge host cell membranes to serve as replication platforms and ZIKV showed the hallmarks of this process. Via TEM, we identified virus particles and 60–100 nm spherular vesicles. ET revealed these vesicular replication compartments contain smaller 20–30 nm spherular structures. Our studies indicate that SK-N-SH and C6/36 cells are relevant models for viral cytoarchitecture study. - Highlights: •First electron tomography of Zika virus cytoarchitecture. •Comparison of Zika virus infection in human neuroblastoma and mosquito cells. •Ultrastructure of Zika virus infection in human neuroblastoma and mosquito cells.

Orientia tsutsugamushi ankyrin repeat-containing protein family members are Type 1 secretion system substrates that traffic to the host cell endoplasmic reticulum.

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VieBrock, Lauren; Evans, Sean M; Beyer, Andrea R; Larson, Charles L; Beare, Paul A; Ge, Hong; Singh, Smita; Rodino, Kyle G; Heinzen, Robert A; Richards, Allen L; Carlyon, Jason A

2014-01-01

Scrub typhus is an understudied, potentially fatal infection that threatens one billion persons in the Asia-Pacific region. How the causative obligate intracellular bacterium, Orientia tsutsugamushi, facilitates its intracellular survival and pathogenesis is poorly understood. Many intracellular bacterial pathogens utilize the Type 1 (T1SS) or Type 4 secretion system (T4SS) to translocate ankyrin repeat-containing proteins (Anks) that traffic to distinct subcellular locations and modulate host cell processes. The O. tsutsugamushi genome encodes one of the largest known bacterial Ank repertoires plus T1SS and T4SS components. Whether these potential virulence factors are expressed during infection, how the Anks are potentially secreted, and to where they localize in the host cell are not known. We determined that O. tsutsugamushi transcriptionally expresses 20 unique ank genes as well as genes for both T1SS and T4SS during infection of mammalian host cells. Examination of the Anks' C-termini revealed that the majority of them resemble T1SS substrates. Escherichia coli expressing a functional T1SS was able to secrete chimeric hemolysin proteins bearing the C-termini of 19 of 20 O. tsutsugamushi Anks in an HlyBD-dependent manner. Thus, O. tsutsugamushi Anks C-termini are T1SS-compatible. Conversely, Coxiella burnetii could not secrete heterologously expressed Anks in a T4SS-dependent manner. Analysis of the subcellular distribution patterns of 20 ectopically expressed Anks revealed that, while 6 remained cytosolic or trafficked to the nucleus, 14 localized to, and in some cases, altered the morphology of the endoplasmic reticulum. This study identifies O. tsutsugamushi Anks as T1SS substrates and indicates that many display a tropism for the host cell secretory pathway.

CD151, a novel host factor of nuclear export signaling in influenza virus infection.

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Qiao, Yongkang; Yan, Yan; Tan, Kai Sen; Tan, Sheryl S L; Seet, Ju Ee; Arumugam, Thiruma Valavan; Chow, Vincent T K; Wang, De Yun; Tran, Thai

2018-05-01

Despite advances in our understanding of the mechanisms of influenza A virus (IAV) infection, the crucial virus-host interactions during the viral replication cycle still remain incomplete. Tetraspanin CD151 is highly expressed in the human respiratory tract, but its pathological role in IAV infection is unknown. We sought to characterize the functional role and mechanisms of action of CD151 in IAV infection of the upper and lower respiratory tracts with H1N1 and H3N2 strains. We used CD151-null mice in an in vivo model of IAV infection and clinical donor samples of in vitro-differentiated human nasal epithelial cells cultured at air-liquid interface. As compared with wild-type infected mice, CD151-null infected mice exhibited a significant reduction in virus titer and improvement in survival that is associated with pronounced host antiviral response and inflammasome activation together with accelerated lung repair. Interestingly, we show that CD151 complexes newly synthesized viral proteins with host nuclear export proteins and stabilizes microtubule complexes, which are key processes necessary for the polarized trafficking of viral progeny to the host plasma membrane for assembly. Our results provide new mechanistic insights into our understanding of IAV infection. We show that CD151 is a critical novel host factor of nuclear export signaling whereby the IAV nuclear export uses it to complement its own nuclear export proteins (a site not targeted by current therapy), making this regulation unique, and holds promise for the development of novel alternative/complementary strategies to reduce IAV severity. Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Host behaviour and physiology underpin individual variation in avian influenza virus infection in migratory Bewick's swans.

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Hoye, Bethany J; Fouchier, Ron A M; Klaassen, Marcel

2012-02-07

Individual variation in infection modulates both the dynamics of pathogens and their impact on host populations. It is therefore crucial to identify differential patterns of infection and understand the mechanisms responsible. Yet our understanding of infection heterogeneity in wildlife is limited, even for important zoonotic host-pathogen systems, owing to the intractability of host status prior to infection. Using novel applications of stable isotope ecology and eco-immunology, we distinguish antecedent behavioural and physiological traits associated with avian influenza virus (AIV) infection in free-living Bewick's swans (Cygnus columbianus bewickii). Swans infected with AIV exhibited higher serum δ13C (-25.3±0.4) than their non-infected counterparts (-26.3±0.2). Thus, individuals preferentially foraging in aquatic rather than terrestrial habitats experienced a higher risk of infection, suggesting that the abiotic requirements of AIV give rise to heterogeneity in pathogen exposure. Juveniles were more likely to be infected (30.8% compared with 11.3% for adults), shed approximately 15-fold higher quantity of virus and exhibited a lower specific immune response than adults. Together, these results demonstrate the potential for heterogeneity in infection to have a profound influence on the dynamics of pathogens, with concomitant impacts on host habitat selection and fitness.

A Fluorescent Cell-Based System for Imaging Zika Virus Infection in Real-Time

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Michael J. McFadden

2018-02-01

Full Text Available Zika virus (ZIKV is a re-emerging flavivirus that is transmitted to humans through the bite of an infected mosquito or through sexual contact with an infected partner. ZIKV infection during pregnancy has been associated with numerous fetal abnormalities, including prenatal lethality and microcephaly. However, until recent outbreaks in the Americas, ZIKV has been relatively understudied, and therefore the biology and pathogenesis of ZIKV infection remain incompletely understood. Better methods to study ZIKV infection in live cells could enhance our understanding of the biology of ZIKV and the mechanisms by which ZIKV contributes to fetal abnormalities. To this end, we developed a fluorescent cell-based reporter system allowing for live imaging of ZIKV-infected cells. This system utilizes the protease activity of the ZIKV non-structural proteins 2B and 3 (NS2B-NS3 to specifically mark virus-infected cells. Here, we demonstrate the utility of this fluorescent reporter for identifying cells infected by ZIKV strains of two lineages. Further, we use this system to determine that apoptosis is induced in cells directly infected with ZIKV in a cell-autonomous manner. Ultimately, approaches that can directly track ZIKV-infected cells at the single cell-level have the potential to yield new insights into the host-pathogen interactions that regulate ZIKV infection and pathogenesis.

Toxoplasma gondii Infection Is Associated with Mitochondrial Dysfunction in-Vitro

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Genevieve Syn

2017-12-01

Full Text Available Upon invasion of host cells, the ubiquitous pathogen Toxoplasma gondii manipulates several host processes, including re-organization of host organelles, to create a replicative niche. Host mitochondrial association to T. gondii parasitophorous vacuoles is rapid and has roles in modulating host immune responses. Here gene expression profiling of T. gondii infected cells reveals enrichment of genes involved in oxidative phosphorylation (OXPHOS and mitochondrial dysfunction 6 h post-infection. We identified 11 hub genes (HIF-1α, CASP8, FN1, POU5F1, CD44, ISG15, HNRNPA1, MDM2, RPL35, VHL, and NUPR1 and 10 predicted upstream regulators, including 4 endogenous regulators RICTOR, KDM5A, RB1, and D-glucose. We characterized a number of mitochondrial parameters in T. gondii infected human foreskin fibroblast cells over a 36 h time-course. In addition to the usual rapid recruitment and apparent enlargement of mitochondria around the parasitophorous vacuole we observed fragmented host mitochondria in infected cells, not linked to cellular apoptosis, from 24 h post-infection. An increase in mitochondrial superoxide levels in T. gondii infected cells was observed that required active parasite invasion and peaked at 30 h post-infection. Measurement of OXPHOS proteins showed decreased expression of Complex IV in infected cells at 24 h post-infection, followed by decreased expression of Complexes I and II at 36 h post-infection. No change occurred in Complex V. No difference in host mitochondrial membrane potential between infected and mock-infected cells was observed at any time. Our results show perturbation of host mitochondrial function following T. gondii infection that likely impacts on pathogenesis of disease.

Alterations in the nuclear proteome of HIV-1 infected T-cells

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DeBoer, Jason; Jagadish, Teena; Haverland, Nicole A.; Madson, Christian J.; Ciborowski, Pawel; Belshan, Michael

2014-01-01

Virus infection of a cell involves the appropriation of host factors and the innate defensive response of the cell. The identification of proteins critical for virus replication may lead to the development of novel, cell-based inhibitors. In this study we mapped the changes in T-cell nuclei during human immunodeficiency virus type 1 (HIV-1) at 20 hpi. Using a stringent data threshold, a total of 13 and 38 unique proteins were identified in infected and uninfected cells, respectively, across all biological replicates. An additional 15 proteins were found to be differentially regulated between infected and control nuclei. STRING analysis identified four clusters of protein–protein interactions in the data set related to nuclear architecture, RNA regulation, cell division, and cell homeostasis. Immunoblot analysis confirmed the differential expression of several proteins in both C8166-45 and Jurkat E6-1 T-cells. These data provide a map of the response in host cell nuclei upon HIV-1 infection. - Highlights: • We identify changes in the expression of nuclear proteins during HIV-1 infection. • 163 nuclear proteins were found differentially regulated during HIV-1 infection. • Bioinformatic analysis identified several nuclear pathways altered by HIV infection. • Candidate factors were validated in two independent cell lines

Alterations in the nuclear proteome of HIV-1 infected T-cells

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DeBoer, Jason [Department of Medical Microbiology and Immunology, Creighton University, 2500 California Plaza, Omaha, NE 68178 (United States); Jagadish, Teena; Haverland, Nicole A. [Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198 (United States); Madson, Christian J. [Department of Medical Microbiology and Immunology, Creighton University, 2500 California Plaza, Omaha, NE 68178 (United States); Ciborowski, Pawel [Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198 (United States); The Nebraska Center for Virology, University of Nebraska, Lincoln 68583 (United States); Belshan, Michael, E-mail: michaelbelshan@creighton.edu [Department of Medical Microbiology and Immunology, Creighton University, 2500 California Plaza, Omaha, NE 68178 (United States); The Nebraska Center for Virology, University of Nebraska, Lincoln 68583 (United States)

2014-11-15

Virus infection of a cell involves the appropriation of host factors and the innate defensive response of the cell. The identification of proteins critical for virus replication may lead to the development of novel, cell-based inhibitors. In this study we mapped the changes in T-cell nuclei during human immunodeficiency virus type 1 (HIV-1) at 20 hpi. Using a stringent data threshold, a total of 13 and 38 unique proteins were identified in infected and uninfected cells, respectively, across all biological replicates. An additional 15 proteins were found to be differentially regulated between infected and control nuclei. STRING analysis identified four clusters of protein–protein interactions in the data set related to nuclear architecture, RNA regulation, cell division, and cell homeostasis. Immunoblot analysis confirmed the differential expression of several proteins in both C8166-45 and Jurkat E6-1 T-cells. These data provide a map of the response in host cell nuclei upon HIV-1 infection. - Highlights: • We identify changes in the expression of nuclear proteins during HIV-1 infection. • 163 nuclear proteins were found differentially regulated during HIV-1 infection. • Bioinformatic analysis identified several nuclear pathways altered by HIV infection. • Candidate factors were validated in two independent cell lines.

Targeting host factors to treat West Nile and dengue viral infections.

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Krishnan, Manoj N; Garcia-Blanco, Mariano A

2014-02-10

West Nile (WNV) and Dengue (DENV) viruses are major arboviral human pathogens belonging to the genus Flavivirus. At the current time, there are no approved prophylactics (e.g., vaccines) or specific therapeutics available to prevent or treat human infections by these pathogens. Due to their minimal genome, these viruses require many host molecules for their replication and this offers a therapeutic avenue wherein host factors can be exploited as treatment targets. Since several host factors appear to be shared by many flaviviruses the strategy may result in pan-flaviviral inhibitors and may also attenuate the rapid emergence of drug resistant mutant viruses. The scope of this strategy is greatly enhanced by the recent en masse identification of host factors impacting on WNV and DENV infection. Excellent proof-of-principle experimental demonstrations for host-targeted control of infection and infection-induced pathogenesis have been reported for both WNV and DENV. These include exploiting not only those host factors supporting infection, but also targeting host processes contributing to pathogenesis and innate immune responses. While these early studies validated the host-targeting approach, extensive future investigations spanning a range of aspects are needed for a successful deployment in humans.

Involvement of Cryptosporidium parvum Cdg7_FLc_1000 RNA in the Attenuation of Intestinal Epithelial Cell Migration via Trans-Suppression of Host Cell SMPD3.

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Ming, Zhenping; Gong, Ai-Yu; Wang, Yang; Zhang, Xin-Tian; Li, Min; Mathy, Nicholas W; Strauss-Soukup, Juliane K; Chen, Xian-Ming

2017-12-27

Intestinal infection by Cryptosporidium parvum causes inhibition of epithelial turnover, but underlying mechanisms are unclear. Previous studies demonstrate that a panel of parasite RNA transcripts of low protein-coding potential are delivered into infected epithelial cells. Using in vitro and in vivo models of intestinal cryptosporidiosis, we report here that host delivery of parasite Cdg7_FLc_1000 RNA results in inhibition of epithelial cell migration through suppression of the gene encoding sphingomyelinase 3 (SMPD3). Delivery of Cdg7_FLc_1000 into infected cells promotes the histone methyltransferase G9a-mediated H3K9 methylation in the SMPD3 locus. The DNA-binding transcriptional repressor, PR domain zinc finger protein 1, is required for the assembly of Cdg7_FLc_1000 into the G9a complex and associated with the enrichment of H3K9 methylation at the gene locus. Pathologically, nuclear transfer of Cryptosporidium parvum Cdg7_FLc_1000 RNA is involved in the attenuation of intestinal epithelial cell migration via trans-suppression of host cell SMPD3. © The Author(s) 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Polymeric mannosides prevent DC-SIGN-mediated cell-infection by cytomegalovirus.

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Brument, S; Cheneau, C; Brissonnet, Y; Deniaud, D; Halary, F; Gouin, S G

2017-09-20

Human cytomegalovirus (HCMV) is a beta-herpesvirus with a high prevalence in the population. HCMV is asymptomatic for immunocompetent adults but is a leading cause of morbidity for new born and immunocompromised patients. It was recently shown that the envelope glycoprotein B (gB) of HCMV interacts with the Dendritic Cell-Specific ICAM-3 Grabbing Non integrin (DC-SIGN) to infect the host. In this work we developed a set of DC-SIGN blockers based on mono-, di-, tetra and polyvalent mannosides. The multivalent mannosides were designed to interact with the carbohydrate recognition domains of DC-SIGN in a chelate or bind and recapture process, and represent the first chemical antiadhesives of HCMV reported so far. Polymeric dextrans coated with triazolylheptylmannoside (THM) ligands were highly potent, blocking the gB and DC-SIGN interaction at nanomolar concentrations. The compounds were further assessed for their ability to prevent the DC-SIGN mediated HCMV infection of dendritic cells. A dextran polymer coated with an average of 902 THM ligands showed an outstanding effect in blocking the HCMV trans-infection with IC 50 values down to the picomolar range (nanomolar when expressed in THM concentration). Each THM moiety on the polymer surpassed the antiadhesive effect of the methylmannoside reference by more than four orders of magnitude. The compound proved non-cytotoxic at the high concentration of 2 mM and therefore represents an interesting antiadhesive candidate against HCMV and potentially against other virus hijacking dendritic cells to infect the host.

Immune response of T cells during herpes simplex virus type 1 (HSV-1) infection.

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Zhang, Jie; Liu, Huan; Wei, Bin

Herpes simplex virus type 1 (HSV-1), a neurotropic member of the alphaherpes virus family, is among the most prevalent and successful human pathogens. HSV-1 can cause serious diseases at every stage of life including fatal disseminated disease in newborns, cold sores, eye disease, and fatal encephalitis in adults. HSV-1 infection can trigger rapid immune responses, and efficient inhibition and clearance of HSV-1 infection rely on both the innate and adaptive immune responses of the host. Multiple strategies have been used to restrict host innate immune responses by HSV-1 to facilitate its infection in host cells. The adaptive immunity of the host plays an important role in inhibiting HSV-1 infections. The activation and regulation of T cells are the important aspects of the adaptive immunity. They play a crucial role in host-mediated immunity and are important for clearing HSV-1. In this review, we examine the findings on T cell immune responses during HSV-1 infection, which hold promise in the design of new vaccine candidates for HSV-1.

Characteristics of siRNAs derived from Southern rice black-streaked dwarf virus in infected rice and their potential role in host gene regulation.

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Xu, Donglin; Zhou, Guohui

2017-02-10

Virus-derived siRNAs (vsiRNAs)-mediated RNA silencing plays important roles in interaction between plant viruses and their hosts. Southern rice black-streaked dwarf virus (SRBSDV) is a newly emerged devastating rice reovirus with ten dsRNA genomic segments. The characteristics of SRBSDV-derived siRNAs and their biological implications in SRBSDV-rice interaction remain unexplored. VsiRNAs profiling from SRBSDV-infected rice samples was done via small RNA deep sequencing. The putative rice targets of abundantly expressed vsiRNAs were bioinformatically predicted and subjected to functional annotation. Differential expression analysis of rice targets and RNA silencing components between infected and healthy samples was done using RT-qPCR. The vsiRNA was barely detectable at 14 days post infection (dpi) but abundantly present along with elevated expression level of the viral genome at 28 dpi. From the 28-dpi sample, 70,878 reads of 18 ~ 30-nt vsiRNAs were recognized (which mostly were 21-nt and 22-nt), covering 75 ~ 91% of the length of the ten genomic segments respectively. 86% of the vsiRNAs had a rice genes, including several types of host resistance or pathogenesis related genes encoding F-box/LRR proteins, receptor-like protein kinases, universal stress proteins, tobamovirus multiplication proteins, and RNA silencing components OsDCL2a and OsAGO17 respectively, some of which showed down regulation in infected plants in RT-qPCR. GO and KEGG classification showed that a majority of the predicted targets were related to cell parts and cellular processes and involved in carbohydrate metabolism, translation, and signal transduction. The silencing component genes OsDCL2a, OsDCL2b, OsDCL4, and OsAGO18 were down regulated, while OsAGO1d, OsAGO2, OsRDR1 and OsRDR6 were up regulated, significantly, upon SRBSDV infection. SRBSDV can regulate the expression of rice RNA silencing pathway components and the virus might compromise host defense and influence host

Relationship between VacA Toxin and Host Cell Autophagy in Helicobacter pylori Infection of the Human Stomach: A Few Answers, Many Questions

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Vittorio Ricci

2016-07-01

Full Text Available Helicobacter pylori is a Gram-negative bacterium that colonizes the stomach of about half the global population and represents the greatest risk factor for gastric malignancy. The relevance of H. pylori for gastric cancer development is equivalent to that of tobacco smoking for lung cancer. VacA toxin seems to play a pivotal role in the overall strategy of H. pylori towards achieving persistent gastric colonization. This strategy appears to involve the modulation of host cell autophagy. After an overview of autophagy and its role in infection and carcinogenesis, I critically review current knowledge about the action of VacA on host cell autophagy during H. pylori infection of the human stomach. Although VacA is a key player in modulation of H. pylori-induced autophagy, a few discrepancies in the data are also evident and many questions remain to be answered. We are thus still far from a definitive understanding of the molecular mechanisms through which VacA affects autophagy and the consequences of this toxin action on the overall pathogenic activity of H. pylori.

Effects of copper nanoparticle exposure on host defense in a murine pulmonary infection model

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Grassian Vicki H

2011-09-01

Full Text Available Abstract Background Human exposure to nanoparticles (NPs and environmental bacteria can occur simultaneously. NPs induce inflammatory responses and oxidative stress but may also have immune-suppressive effects, impairing macrophage function and altering epithelial barrier functions. The purpose of this study was to assess the potential pulmonary effects of inhalation and instillation exposure to copper (Cu NPs using a model of lung inflammation and host defense. Methods We used Klebsiella pneumoniae (K.p. in a murine lung infection model to determine if pulmonary bacterial clearance is enhanced or impaired by Cu NP exposure. Two different exposure modes were tested: sub-acute inhalation (4 hr/day, 5 d/week for 2 weeks, 3.5 mg/m3 and intratracheal instillation (24 hr post-exposure, 3, 35, and 100 μg/mouse. Pulmonary responses were evaluated by lung histopathology plus measurement of differential cell counts, total protein, lactate dehydrogenase (LDH activity, and inflammatory cytokines in bronchoalveolar lavage (BAL fluid. Results Cu NP exposure induced inflammatory responses with increased recruitment of total cells and neutrophils to the lungs as well as increased total protein and LDH activity in BAL fluid. Both inhalation and instillation exposure to Cu NPs significantly decreased the pulmonary clearance of K.p.-exposed mice measured 24 hr after bacterial infection following Cu NP exposure versus sham-exposed mice also challenged with K.p (1.4 × 105 bacteria/mouse. Conclusions Cu NP exposure impaired host defense against bacterial lung infections and induced a dose-dependent decrease in bacterial clearance in which even our lowest dose demonstrated significantly lower clearance than observed in sham-exposed mice. Thus, exposure to Cu NPs may increase the risk of pulmonary infection.

Virus-host interaction in feline immunodeficiency virus (FIV) infection.

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Taniwaki, Sueli Akemi; Figueiredo, Andreza Soriano; Araujo, João Pessoa

2013-12-01

Feline immunodeficiency virus (FIV) infection has been the focus of several studies because this virus exhibits genetic and pathogenic characteristics that are similar to those of the human immunodeficiency virus (HIV). FIV causes acquired immunodeficiency syndrome (AIDS) in cats, nevertheless, a large fraction of infected cats remain asymptomatic throughout life despite of persistent chronic infection. This slow disease progression may be due to the presence of factors that are involved in the natural resistance to infection and the immune response that is mounted by the animals, as well as due to the adaptation of the virus to the host. Therefore, the study of virus-host interaction is essential to the understanding of the different patterns of disease course and the virus persistence in the host, and to help with the development of effective vaccines and perhaps the cure of FIV and HIV infections. Copyright © 2013 Elsevier Ltd. All rights reserved.

Host cell subversion by Toxoplasma GRA16, an exported dense granule protein that targets the host cell nucleus and alters gene expression.

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Bougdour, Alexandre; Durandau, Eric; Brenier-Pinchart, Marie-Pierre; Ortet, Philippe; Barakat, Mohamed; Kieffer, Sylvie; Curt-Varesano, Aurélie; Curt-Bertini, Rose-Laurence; Bastien, Olivier; Coute, Yohann; Pelloux, Hervé; Hakimi, Mohamed-Ali

2013-04-17

After invading host cells, Toxoplasma gondii multiplies within a parasitophorous vacuole (PV) that is maintained by parasite proteins secreted from organelles called dense granules. Most dense granule proteins remain within the PV, and few are known to access the host cell cytosol. We identify GRA16 as a dense granule protein that is exported through the PV membrane and reaches the host cell nucleus, where it positively modulates genes involved in cell-cycle progression and the p53 tumor suppressor pathway. GRA16 binds two host enzymes, the deubiquitinase HAUSP and PP2A phosphatase, which exert several functions, including regulation of p53 and the cell cycle. GRA16 alters p53 levels in a HAUSP-dependent manner and induces nuclear translocation of the PP2A holoenzyme. Additionally, certain GRA16-deficient strains exhibit attenuated virulence, indicating the importance of these host alterations in pathogenesis. Therefore, GRA16 represents a potentially emerging subfamily of exported dense granule proteins that modulate host function. Copyright © 2013 Elsevier Inc. All rights reserved.

Animal herpesviruses and their zoonotic potential for cross-species infection

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Grzegorz Woźniakowski

2015-05-01

Full Text Available Herpesviruses of humans and animals cause severe diseases that influence not only the health and epidemiological status but are also economically important in the context of food production. The members of Herpesviridae are host specific agents that also share many properties that potentially make them capable of crossing the species barriers. The objective of presented review paper was to summarize the relationship between herpesviruses of animals and humans and their zoonotic potential. In humans, the most epidemiologically important herpesviruses are represented by Human herepesvirus-1 and Human herpesvirus-2, which are commonly known as herpes simplex virus type 1 and 2, varicella-zooster virus (VZV, Epstein-Barr virus (EBV, Kaposi’s Sarcoma-associated herpesvirus (KSHV, cytomegalovirus (CMV, as well as Human herpesviruses: HHV-6A, HHV-6B, and HHV-7. However, in terms of the potential to cross the species barrier, there are a few herpesviruses, including B virus disease (CeHV-1, Marek’s disease virus (MDV, Equid herpesvirus-1 (EHV-1 or pseudorabies virus (PRV, which are potentially able to infect different hosts. To summarize, in advantageous conditions the host specific herpesviruses may pose a threat for public health but also may exert a negative impact on the economical aspects of animal production. The most probable of these are zoonotic infections caused by B virus disease; however, close contact between infected animal hosts and humans may lead to transmission and replication of other Herpesviridae members.

Shigella reroutes host cell central metabolism to obtain high-flux nutrient supply for vigorous intracellular growth.

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Kentner, David; Martano, Giuseppe; Callon, Morgane; Chiquet, Petra; Brodmann, Maj; Burton, Olga; Wahlander, Asa; Nanni, Paolo; Delmotte, Nathanaël; Grossmann, Jonas; Limenitakis, Julien; Schlapbach, Ralph; Kiefer, Patrick; Vorholt, Julia A; Hiller, Sebastian; Bumann, Dirk

2014-07-08

Shigella flexneri proliferate in infected human epithelial cells at exceptionally high rates. This vigorous growth has important consequences for rapid progression to life-threatening bloody diarrhea, but the underlying metabolic mechanisms remain poorly understood. Here, we used metabolomics, proteomics, and genetic experiments to determine host and Shigella metabolism during infection in a cell culture model. The data suggest that infected host cells maintain largely normal fluxes through glycolytic pathways, but the entire output of these pathways is captured by Shigella, most likely in the form of pyruvate. This striking strategy provides Shigella with an abundant favorable energy source, while preserving host cell ATP generation, energy charge maintenance, and survival, despite ongoing vigorous exploitation. Shigella uses a simple three-step pathway to metabolize pyruvate at high rates with acetate as an excreted waste product. The crucial role of this pathway for Shigella intracellular growth suggests targets for antimicrobial chemotherapy of this devastating disease.

RNAi screen reveals an Abl kinase-dependent host cell pathway involved in Pseudomonas aeruginosa internalization.

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Julia F Pielage

2008-03-01

Full Text Available Internalization of the pathogenic bacterium Pseudomonas aeruginosa by non-phagocytic cells is promoted by rearrangements of the actin cytoskeleton, but the host pathways usurped by this bacterium are not clearly understood. We used RNAi-mediated gene inactivation of approximately 80 genes known to regulate the actin cytoskeleton in Drosophila S2 cells to identify host molecules essential for entry of P. aeruginosa. This work revealed Abl tyrosine kinase, the adaptor protein Crk, the small GTPases Rac1 and Cdc42, and p21-activated kinase as components of a host signaling pathway that leads to internalization of P. aeruginosa. Using a variety of complementary approaches, we validated the role of this pathway in mammalian cells. Remarkably, ExoS and ExoT, type III secreted toxins of P. aeruginosa, target this pathway by interfering with GTPase function and, in the case of ExoT, by abrogating P. aeruginosa-induced Abl-dependent Crk phosphorylation. Altogether, this work reveals that P. aeruginosa utilizes the Abl pathway for entering host cells and reveals unexpected complexity by which the P. aeruginosa type III secretion system modulates this internalization pathway. Our results furthermore demonstrate the applicability of using RNAi screens to identify host signaling cascades usurped by microbial pathogens that may be potential targets for novel therapies directed against treatment of antibiotic-resistant infections.

Modulation of antigen presenting cell functions during chronic HPV infection

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Abate Assefa Bashaw

2017-12-01

Full Text Available High-risk human papillomaviruses (HR-HPV infect basal keratinocytes, where in some individuals they evade host immune responses and persist. Persistent HR-HPV infection of the cervix causes precancerous neoplasia that can eventuate in cervical cancer. Dendritic cells (DCs are efficient in priming/cross-priming antigen-specific T cells and generating antiviral and antitumor cytotoxic CD8+ T cells. However, HR-HPV have adopted various immunosuppressive strategies, with modulation of DC function crucial to escape from the host adaptive immune response. HPV E6 and E7 oncoproteins alter recruitment and localization of epidermal DCs, while soluble regulatory factors derived from HPV-induced hyperplastic epithelium change DC development and influence initiation of specific cellular immune responses. This review focuses on current evidence for HR-HPV manipulation of antigen presentation in dendritic cells and escape from host immunity.

Electron Microscopy of Ebola Virus-Infected Cells.

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Noda, Takeshi

2017-01-01

Ebola virus (EBOV) replicates in host cells, where both viral and cellular components show morphological changes during the process of viral replication from entry to budding. These steps in the replication cycle can be studied using electron microscopy (EM), including transmission electron microscopy (TEM) and scanning electron microscopy (SEM), which is one of the most useful methods for visualizing EBOV particles and EBOV-infected cells at the ultrastructural level. This chapter describes conventional methods for EM sample preparation of cultured cells infected with EBOV.

Long-term infection and vertical transmission of a gammaretrovirus in a foreign host species.

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Sakuma, Toshie; Tonne, Jason M; Malcolm, Jessica A; Thatava, Tayaramma; Ohmine, Seiga; Peng, Kah-Whye; Ikeda, Yasuhiro

2012-01-01

Increasing evidence has indicated natural transspecies transmission of gammaretroviruses; however, viral-host interactions after initial xeno-exposure remain poorly understood. Potential association of xenotropic murine leukemia virus-related virus (XMRV) in patients with prostate cancer and chronic fatigue syndrome has attracted broad interests in this topic. Although recent studies have indicated that XMRV is unlikely a human pathogen, further understanding of XMRV xenoinfection would allow in vivo modeling of the initial steps of gammaretroviral interspecies transmission, evolution and dissemination in a new host population. In this study, we monitored the long-term consequences of XMRV infection and its possible vertical transmission in a permissive foreign host, wild-derived Mus pahari mice. One year post-infection, XMRV-infected mice showed no notable pathological changes, while proviral DNA was detected in three out of eight mice. XMRV-infected mice remained seropositive throughout the study although the levels of gp70 Env- and p30 capsid-specific antibodies gradually decreased. When vertical XMRV transmission was assessed, no viremia, humoral immune responses nor endogenization were observed in nine offspring from infected mothers, yet one offspring was found PCR-positive for XMRV-specific sequences. Amplified viral sequences from the offspring showed several mutations, including one amino acid deletion in the receptor binding domain of Env SU. Our results therefore demonstrate long-term asymptomatic infection, low incidence of vertical transmission and limited evolution of XMRV upon transspecies infection of a permissive new host, Mus pahari.

Long-term infection and vertical transmission of a gammaretrovirus in a foreign host species.

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Toshie Sakuma

Full Text Available Increasing evidence has indicated natural transspecies transmission of gammaretroviruses; however, viral-host interactions after initial xeno-exposure remain poorly understood. Potential association of xenotropic murine leukemia virus-related virus (XMRV in patients with prostate cancer and chronic fatigue syndrome has attracted broad interests in this topic. Although recent studies have indicated that XMRV is unlikely a human pathogen, further understanding of XMRV xenoinfection would allow in vivo modeling of the initial steps of gammaretroviral interspecies transmission, evolution and dissemination in a new host population. In this study, we monitored the long-term consequences of XMRV infection and its possible vertical transmission in a permissive foreign host, wild-derived Mus pahari mice. One year post-infection, XMRV-infected mice showed no notable pathological changes, while proviral DNA was detected in three out of eight mice. XMRV-infected mice remained seropositive throughout the study although the levels of gp70 Env- and p30 capsid-specific antibodies gradually decreased. When vertical XMRV transmission was assessed, no viremia, humoral immune responses nor endogenization were observed in nine offspring from infected mothers, yet one offspring was found PCR-positive for XMRV-specific sequences. Amplified viral sequences from the offspring showed several mutations, including one amino acid deletion in the receptor binding domain of Env SU. Our results therefore demonstrate long-term asymptomatic infection, low incidence of vertical transmission and limited evolution of XMRV upon transspecies infection of a permissive new host, Mus pahari.

A novel mechanism of bacterial toxin transfer within host blood cell-derived microvesicles.

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Anne-lie Ståhl

2015-02-01

Full Text Available Shiga toxin (Stx is the main virulence factor of enterohemorrhagic Escherichia coli, which are non-invasive strains that can lead to hemolytic uremic syndrome (HUS, associated with renal failure and death. Although bacteremia does not occur, bacterial virulence factors gain access to the circulation and are thereafter presumed to cause target organ damage. Stx was previously shown to circulate bound to blood cells but the mechanism by which it would potentially transfer to target organ cells has not been elucidated. Here we show that blood cell-derived microvesicles, shed during HUS, contain Stx and are found within patient renal cortical cells. The finding was reproduced in mice infected with Stx-producing Escherichia coli exhibiting Stx-containing blood cell-derived microvesicles in the circulation that reached the kidney where they were transferred into glomerular and peritubular capillary endothelial cells and further through their basement membranes followed by podocytes and tubular epithelial cells, respectively. In vitro studies demonstrated that blood cell-derived microvesicles containing Stx undergo endocytosis in glomerular endothelial cells leading to cell death secondary to inhibited protein synthesis. This study demonstrates a novel virulence mechanism whereby bacterial toxin is transferred within host blood cell-derived microvesicles in which it may evade the host immune system.

Targeting Host Factors to Treat West Nile and Dengue Viral Infections

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Manoj N. Krishnan

2014-02-01

Full Text Available West Nile (WNV and Dengue (DENV viruses are major arboviral human pathogens belonging to the genus Flavivirus. At the current time, there are no approved prophylactics (e.g., vaccines or specific therapeutics available to prevent or treat human infections by these pathogens. Due to their minimal genome, these viruses require many host molecules for their replication and this offers a therapeutic avenue wherein host factors can be exploited as treatment targets. Since several host factors appear to be shared by many flaviviruses the strategy may result in pan-flaviviral inhibitors and may also attenuate the rapid emergence of drug resistant mutant viruses. The scope of this strategy is greatly enhanced by the recent en masse identification of host factors impacting on WNV and DENV infection. Excellent proof-of-principle experimental demonstrations for host-targeted control of infection and infection-induced pathogenesis have been reported for both WNV and DENV. These include exploiting not only those host factors supporting infection, but also targeting host processes contributing to pathogenesis and innate immune responses. While these early studies validated the host-targeting approach, extensive future investigations spanning a range of aspects are needed for a successful deployment in humans.

Time-Course Study of the Transcriptome of Peripheral Blood Mononuclear Cells (PBMCs) from Sheep Infected with Fasciola hepatica

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Scheerlinck, Jean-Pierre; Ansell, Brendan R. E.; Hall, Ross S.; Gasser, Robin B.; Jex, Aaron R.

2016-01-01

Fasciola hepatica is a parasitic trematode that infects a wide range of mammalian hosts, including livestock and humans, in temperate and tropical regions globally. This trematode causes the disease fascioliasis, which consists of an acute phase (≤ 12 weeks) during which juvenile parasites migrate through the host liver tissues, and a chronic phase (> 12 weeks) following the establishment of adult parasites in the liver bile ducts. Few studies have explored the progression of the host response over the course of Fasciola infection in the same animals. In this study, we characterized transcriptomic changes in peripheral blood mononuclear cells (PBMCs) collected from sheep at three time points over the first eight weeks of infection relative to uninfected controls. In total, 183 and 76 genes were found to be differentially transcribed at two and eight weeks post-infection respectively. Functional and pathway analysis of differentially transcribed genes revealed changes related to T-cell activation that may underpin a Th2-biased immune response against this parasite. This first insight into the dynamics of host responses during the early stages of infection improves the understanding of the pathogenesis of acute fascioliasis, informs vaccine development and presents a set of PBMC markers with diagnostic potential. PMID:27438474

Time-Course Study of the Transcriptome of Peripheral Blood Mononuclear Cells (PBMCs from Sheep Infected with Fasciola hepatica.

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Cristian A Alvarez Rojas

Full Text Available Fasciola hepatica is a parasitic trematode that infects a wide range of mammalian hosts, including livestock and humans, in temperate and tropical regions globally. This trematode causes the disease fascioliasis, which consists of an acute phase (≤ 12 weeks during which juvenile parasites migrate through the host liver tissues, and a chronic phase (> 12 weeks following the establishment of adult parasites in the liver bile ducts. Few studies have explored the progression of the host response over the course of Fasciola infection in the same animals. In this study, we characterized transcriptomic changes in peripheral blood mononuclear cells (PBMCs collected from sheep at three time points over the first eight weeks of infection relative to uninfected controls. In total, 183 and 76 genes were found to be differentially transcribed at two and eight weeks post-infection respectively. Functional and pathway analysis of differentially transcribed genes revealed changes related to T-cell activation that may underpin a Th2-biased immune response against this parasite. This first insight into the dynamics of host responses during the early stages of infection improves the understanding of the pathogenesis of acute fascioliasis, informs vaccine development and presents a set of PBMC markers with diagnostic potential.

The effect of Bulgarian propolis against Trypanosoma cruzi and during its interaction with host cells

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Andréia Pires Dantas

2006-03-01

Full Text Available Propolis has shown activity against pathogenic microorganisms that cause diseases in humans and animals. The ethanol (Et-Blg and acetone (Ket-Blg extracts from a Bulgarian propolis, with known chemical compositions, presented similar activity against tissue culture-derived amastigotes. The treatment of Trypanosoma cruzi-infected skeletal muscle cells with Et-Blg led to a decrease of infection and of the intracellular proliferation of amastigotes, while damage to the host cell was observed only at concentration 12.5 times higher than those affecting the parasite. Ultrastructural analysis of the effect of both extracts in epimastigotes revealed that the main targets were the mitochondrion and reservosomes. Et-Blg also affected the mitochondrion-kinetoplast complex in trypomastigotes, offering a potential target for chemotherapeutic agents.

A Multi-Omic View of Host-Pathogen-Commensal Interplay in Salmonella-Mediated Intestinal Infection

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Kaiser, Brooke LD; Li, Jie; Sanford, James A.; Kim, Young-Mo; Kronewitter, Scott R.; Jones, Marcus B.; Peterson, Christine; Peterson, Scott N.; Frank, Bryan C.; Purvine, Samuel O.; Brown, Joseph N.; Metz, Thomas O.; Smith, Richard D.; Heffron, Fred; Adkins, Joshua N.

2013-06-26

The potential for commensal microorganisms indigenous to a host (the ‘microbiome’ or ‘microbiota’) to alter infection outcome by influencing host-pathogen interplay is largely unknown. We used a multi-omics “systems” approach, incorporating proteomics, metabolomics, glycomics, and metagenomics, to explore the molecular interplay between the murine host, the pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium), and commensal gut microorganisms during intestinal infection with S. Typhimurium. We find proteomic evidence that S. Typhimurium thrives within the infected 129/SvJ mouse gut without antibiotic pre-treatment, inducing inflammation and disrupting the intestinal microbiome (e.g., suppressing Bacteroidetes and Firmicutes while promoting growth of Salmonella and Enterococcus). Alteration of the host microbiome population structure was highly correlated with gut environmental changes, including the accumulation of metabolites normally consumed by commensal microbiota. Finally, the less characterized phase of S. Typhimurium’s lifecycle was investigated, and both proteomic and glycomic evidence suggests S. Typhimurium may take advantage of increased fucose moieties to metabolize fucose while growing in the gut. The application of multiple omics measurements to Salmonella-induced intestinal inflammation provides insights into complex molecular strategies employed during pathogenesis between host, pathogen, and the microbiome.

Rapid host immune response and viral dynamics in herpes simplex virus-2 infection

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Schiffer, Joshua T; Corey, Lawrence

2014-01-01

Herpes Simplex Virus-2 (HSV-2) is episodically shed throughout the human genital tract. While high viral load correlates with development of genital ulcers, shedding also commonly occurs even when ulcers are not present, allowing for silent transmission during coitus and contributing to high seroprevalence of HSV-2 worldwide. Frequent viral reactivation occurs despite diverse and complementary host and viral mechanisms within ganglionic tissue that predispose towards latency, suggesting that viral replication may be constantly occurring in a small minority of neurons within the ganglia. Within genital mucosa, the in vivo expansion and clearance rates of HSV-2 are extremely rapid. Resident dendritic cells and memory HSV-specific T cells persist at prior sites of genital tract reactivation, and in conjunction with prompt innate recognition of infected cells, lead to rapid containment of infected cells. Shedding episodes vary greatly in duration and severity within a single person over time: this heterogeneity appears best explained by variation in the densities of host immunity across the genital tract. The fact that immune responses usually control viral replication in genital skin prior to development of lesions provides optimism that enhancing such responses could lead to effective vaccines and immunotherapies. PMID:23467247

Cytotoxic CD4 T Cells: Differentiation, Function, and Application to Dengue Virus Infection.

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Tian, Yuan; Sette, Alessandro; Weiskopf, Daniela

2016-01-01

Dengue virus (DENV) has spread through most tropical and subtropical areas of the world and represents a serious public health problem. The control of DENV infection has not yet been fully successful due to lack of effective therapeutics or vaccines. Nevertheless, a better understanding of the immune responses against DENV infection may reveal new strategies for eliciting and improving antiviral immunity. T cells provide protective immunity against various viral infections by generating effector cells that cooperate to eliminate antigens and memory cells that can survive for long periods with enhanced abilities to control recurring pathogens. Following activation, CD8 T cells can migrate to sites of infection and kill infected cells, whereas CD4 T cells contribute to the elimination of pathogens by trafficking to infected tissues and providing help to innate immune responses, B cells, as well as CD8 T cells. However, it is now evident that CD4 T cells can also perform cytotoxic functions and induce the apoptosis of target cells. Importantly, accumulating studies demonstrate that cytotoxic CD4 T cells develop following DENV infections and may play a crucial role in protecting the host from severe dengue disease. We review our current understanding of the differentiation and function of cytotoxic CD4 T cells, with a focus on DENV infection, and discuss the potential of harnessing these cells for the prevention and treatment of DENV infection and disease.

IL-18 potentiated whole blood IFN-γ assay can identify cell-mediated immune responses towards Lawsonia intracellularis in experimentally infected pigs

DEFF Research Database (Denmark)

Riber, Ulla; Jakobsen, Jeanne Toft; Hvass, Henriette Cordes

Lawsonia intracellularis is an obligate intracellular bacteria causing proliferative enteropathy (PE) in pigs. The infection causes diarrhoea, retarded growth and sudden death in pigs and is one of the most economically important diseases in the swine industry worldwide. The infection is one...... indications that cell-mediated immune responses (CMI) are important for the protection against infections with L. intracellularis and in mice models IFN-γ has been shown to play a key role in the host defence against experimental infections . In L. intracellularis infected pigs, IFN-γ is only sparsely...

RNAi screen reveals host cell kinases specifically involved in Listeria monocytogenes spread from cell to cell.

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Ryan Chong

Full Text Available Intracellular bacterial pathogens, such as Listeria monocytogenes and Rickettsia conorii display actin-based motility in the cytosol of infected cells and spread from cell to cell through the formation of membrane protrusions at the cell cortex. Whereas the mechanisms supporting cytosolic actin-based motility are fairly well understood, it is unclear whether specific host factors may be required for supporting the formation and resolution of membrane protrusions. To address this gap in knowledge, we have developed high-throughput fluorescence microscopy and computer-assisted image analysis procedures to quantify pathogen spread in human epithelial cells. We used the approach to screen a siRNA library covering the human kinome and identified 7 candidate kinases whose depletion led to severe spreading defects in cells infected with L. monocytogenes. We conducted systematic validation procedures with redundant silencing reagents and confirmed the involvement of the serine/threonine kinases, CSNK1A1 and CSNK2B. We conducted secondary assays showing that, in contrast with the situation observed in CSNK2B-depleted cells, L. monocytogenes formed wild-type cytosolic tails and displayed wild-type actin-based motility in the cytosol of CSNK1A1-depleted cells. Furthermore, we developed a protrusion formation assay and showed that the spreading defect observed in CSNK1A1-depleted cells correlated with the formation of protrusion that did not resolve into double-membrane vacuoles. Moreover, we developed sending and receiving cell-specific RNAi procedures and showed that CSNK1A was required in the sending cells, but was dispensable in the receiving cells, for protrusion resolution. Finally, we showed that the observed defects were specific to Listeria monocytogenes, as Rickettsia conorii displayed wild-type cell-to-cell spread in CSNK1A1- and CSNK2B-depleted cells. We conclude that, in addition to the specific host factors supporting cytosolic actin

Flavivirus infection from mosquitoes in vitro reveals cell entry at the plasma membrane

International Nuclear Information System (INIS)

Vancini, Ricardo; Kramer, Laura D.; Ribeiro, Mariana; Hernandez, Raquel; Brown, Dennis

2013-01-01

Dengue and West Nile viruses are enveloped RNA viruses that belong to genus Flavivirus (family Flaviviridae) and are considered important mosquito-borne viral pathogenic agents worldwide. A potential target for intervention strategies is the virus cell entry mechanism. Previous studies of flavivirus entry have focused on the effects of biochemical and molecular inhibitors on viral entry leading to controversial conclusions suggesting that the process is dependent upon endocytosis and low pH mediated membrane fusion. In this study we analyzed the early events in the infection process by means of electron microscopy and immuno-gold labeling of viral particles during cell entry, and used as a new approach for infecting cells with viruses obtained directly from mosquitoes. The results show that Dengue and West Nile viruses may infect cells by a mechanism that involves direct penetration of the host cell plasma membrane as proposed for alphaviruses.

Flavivirus infection from mosquitoes in vitro reveals cell entry at the plasma membrane

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Vancini, Ricardo [Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC (United States); Kramer, Laura D. [Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany, Albany, NY (United States); Ribeiro, Mariana; Hernandez, Raquel [Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC (United States); Brown, Dennis, E-mail: dennis_brown@ncsu.edu [Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC (United States)

2013-01-20

Dengue and West Nile viruses are enveloped RNA viruses that belong to genus Flavivirus (family Flaviviridae) and are considered important mosquito-borne viral pathogenic agents worldwide. A potential target for intervention strategies is the virus cell entry mechanism. Previous studies of flavivirus entry have focused on the effects of biochemical and molecular inhibitors on viral entry leading to controversial conclusions suggesting that the process is dependent upon endocytosis and low pH mediated membrane fusion. In this study we analyzed the early events in the infection process by means of electron microscopy and immuno-gold labeling of viral particles during cell entry, and used as a new approach for infecting cells with viruses obtained directly from mosquitoes. The results show that Dengue and West Nile viruses may infect cells by a mechanism that involves direct penetration of the host cell plasma membrane as proposed for alphaviruses.

Identification of host response signatures of infection.

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Branda, Steven S.; Sinha, Anupama; Bent, Zachary

2013-02-01

Biological weapons of mass destruction and emerging infectious diseases represent a serious and growing threat to our national security. Effective response to a bioattack or disease outbreak critically depends upon efficient and reliable distinguishing between infected vs healthy individuals, to enable rational use of scarce, invasive, and/or costly countermeasures (diagnostics, therapies, quarantine). Screening based on direct detection of the causative pathogen can be problematic, because culture- and probe-based assays are confounded by unanticipated pathogens (e.g., deeply diverged, engineered), and readily-accessible specimens (e.g., blood) often contain little or no pathogen, particularly at pre-symptomatic stages of disease. Thus, in addition to the pathogen itself, one would like to detect infection-specific host response signatures in the specimen, preferably ones comprised of nucleic acids (NA), which can be recovered and amplified from tiny specimens (e.g., fingerstick draws). Proof-of-concept studies have not been definitive, however, largely due to use of sub-optimal sample preparation and detection technologies. For purposes of pathogen detection, Sandia has developed novel molecular biology methods that enable selective isolation of NA unique to, or shared between, complex samples, followed by identification and quantitation via Second Generation Sequencing (SGS). The central hypothesis of the current study is that variations on this approach will support efficient identification and verification of NA-based host response signatures of infectious disease. To test this hypothesis, we re-engineered Sandia's sophisticated sample preparation pipelines, and developed new SGS data analysis tools and strategies, in order to pioneer use of SGS for identification of host NA correlating with infection. Proof-of-concept studies were carried out using specimens drawn from pathogen-infected non-human primates (NHP). This work provides a strong foundation for

Survival relative to new and ancestral host plants, phytoplasma infection, and genetic constitution in host races of a polyphagous insect disease vector

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Maixner, Michael; Albert, Andreas; Johannesen, Jes

2014-01-01

Dissemination of vectorborne diseases depends strongly on the vector's host range and the pathogen's reservoir range. Because vectors interact with pathogens, the direction and strength of a vector's host shift is vital for understanding epidemiology and is embedded in the framework of ecological specialization. This study investigates survival in host-race evolution of a polyphagous insect disease vector, Hyalesthes obsoletus, whether survival is related to the direction of the host shift (from field bindweed to stinging nettle), the interaction with plant-specific strains of obligate vectored pathogens/symbionts (stolbur phytoplasma), and whether survival is related to genetic differentiation between the host races. We used a twice repeated, identical nested experimental design to study survival of the vector on alternative hosts and relative to infection status. Survival was tested with Kaplan–Meier analyses, while genetic differentiation between vector populations was quantified with microsatellite allele frequencies. We found significant direct effects of host plant (reduced survival on wrong hosts) and sex (males survive longer than females) in both host races and relative effects of host (nettle animals more affected than bindweed animals) and sex (males more affected than females). Survival of bindweed animals was significantly higher on symptomatic than nonsymptomatic field bindweed, but in the second experiment only. Infection potentially had a positive effect on survival in nettle animals but due to low infection rates the results remain suggestive. Genetic differentiation was not related to survival. Greater negative plant-transfer effect but no negative effect of stolbur in the derived host race suggests preadaptation to the new pathogen/symbiont strain before strong diversifying selection during the specialization process. Physiological maladaptation or failure to accept the ancestral plant will have similar consequences, namely positive assortative

Comparative proteomics analysis of apoptotic Spodoptera frugiperda cells during p35 knockout Autographa californica multiple nucleopolyhedrovirus infection.

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Yu, Qian; Xiong, Youhua; Liu, Jianliang; Wang, Qin; Qiu, Yuanxin; Wen, Dongling

2016-06-01

Infection with Autographa californica multiple nucleopolyhedrovirus (AcMNPV) mutants lacking a functional p35 gene can induce host cell apoptosis, which provides the possibility to use the potential of these viruses in the biological control of pest insects. Nonetheless, the proteomics or the protein changes of Spodoptera frugiperda (Sf9) cells infected with p35 knockout AcMNPV have not yet been studied. To further improve the use of AcMNPV, we set out to analyze the protein composition and protein changes of Sf9 cells of different infection stages by isobaric tag for relative and absolute quantification (iTRAQ) techniques. A total of 4004 sf9 proteins were identified by iTRAQ. After comparation of the significantly expressed 483 proteins from p35koAcMNPV-infected Sf9 cells and the significantly expressed 413 proteins from wtAcMNPV-infected Sf9 cells, we found that 226 proteins were specific to p35koAcMNPV-infected Sf9 cells. The 226 proteins were categorized according to GO classification for insects and were categorized into: biological processes, molecular functions and cellular components. Of interest, the most up-regulated proteins related to Epstein-Barr virus infection, RNA transport, Calcium signaling pathway, cGMP-PKG signaling pathway, oxidative phosphorylation and N-Glycan biosynthesis. Determination of the protein changes in p35 knockout AcMNPV-infected Sf9 cells would facilitate the better use of this virus-host cell interaction in pest insect control and other related fields. Copyright © 2016 Elsevier Inc. All rights reserved.

Nipah virus infects specific subsets of porcine peripheral blood mononuclear cells.

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Beata Stachowiak

Full Text Available Nipah virus (NiV, a zoonotic paramyxovirus, is highly contagious in swine, and can cause fatal infections in humans following transmission from the swine host. The main viral targets in both species are the respiratory and central nervous systems, with viremia implicated as a mode of dissemination of NiV throughout the host. The presented work focused on the role of peripheral blood mononuclear cells (PBMC in the viremic spread of the virus in the swine host. B lymphocytes, CD4-CD8-, as well as CD4+CD8- T lymphocytes were not permissive to NiV, and expansion of the CD4+CD8- cells early post infection was consistent with functional humoral response to NiV infection observed in swine. In contrast, significant drop in the CD4+CD8- T cell frequency was observed in piglets which succumbed to the experimental infection, supporting the hypothesis that antibody development is the critical component of the protective immune response. Productive viral replication was detected in monocytes, CD6+CD8+ T lymphocytes and NK cells by recovery of infectious virus in the cell supernatants. Virus replication was supported by detection of the structural N and the non-structural C proteins or by detection of genomic RNA increase in the infected cells. Infection of T cells carrying CD6 marker, a strong ligand for the activated leukocyte cell adhesion molecule ALCAM (CD166 highly expressed on the microvascular endothelial cell of the blood-air and the blood-brain barrier may explain NiV preferential tropism for small blood vessels of the lung and brain.

Resiniferatoxin modulates the Th1 immune response and protects the host during intestinal nematode infection.

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Muñoz-Carrillo, J L; Contreras-Cordero, J F; Muñoz-López, J L; Maldonado-Tapia, C H; Muñoz-Escobedo, J J; Moreno-García, M A

2017-09-01

In the early stage of the intestinal phase of Trichinella spiralis infection, the host triggers a Th1-type immune response with the aim of eliminating the parasite. However, this response damages the host which favours the survival of the parasite. In the search for novel pharmacological strategies that inhibit the Th1 immune response and assist the host against T. spiralis infection, a recent study showed that resiniferatoxin had anti-inflammatory activity contributed to the host in T. spiralis infection. In this study, we evaluated whether RTX modulates the host immune response through the inhibition of Th1 cytokines in the intestinal phase. In addition, it was determined whether the treatment with RTX affects the infectivity of T. spiralis-L1 and the development of the T. spiralis life cycle. Our results show that RTX decreased serum levels of IL-12, INF-γ, IL-1β, TNF-α and parasite burden on muscle tissue. It was observed that T. spiralis-L1 treated with RTX decreased their infectivity affecting the development of the T. spiralis life cycle in mouse. These results demonstrate that RTX is able to inhibit the production of Th1 cytokines, contributing to the defence against T. spiralis, which places it as a potential drug modulator of the immune response. © 2017 John Wiley & Sons Ltd.

Easy labeling of proliferative phase and sporogonic phase of microsporidia Nosema bombycis in host cells.

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Jie Chen

Full Text Available Microsporidia are eukaryotic, unicellular parasites that have been studied for more than 150 years. These organisms are extraordinary in their ability to invade a wide range of hosts including vertebrates and invertebrates, such as human and commercially important animals. A lack of appropriate labeling methods has limited the research of the cell cycle and protein locations in intracellular stages. In this report, an easy fluorescent labeling method has been developed to mark the proliferative and sporogonic phases of microsporidia Nosema bombycis in host cells. Based on the presence of chitin, Calcofluor White M2R was used to label the sporogonic phase, while β-tubulin antibody coupled with fluorescence secondary antibody were used to label the proliferative phase by immunofluorescence. This method is simple, efficient and can be used on both infected cells and tissue slices, providing a great potential application in microsporidia research.

Tumor Necrosis Factor-α Is Required for Mast Cell-Mediated Host Immunity Against Cutaneous Staphylococcus aureus Infection.

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Liu, Chao; Ouyang, Wei; Xia, Jingyan; Sun, Xiaoru; Zhao, Liying; Xu, Feng

2018-05-08

Mast cells (MCs) play a key role in immune process response to invading pathogens. This study assessed the involvement of MCs in controlling Staphylococcus aureus infection in a cutaneous infection model of MC-deficient (KitW-sh/W-sh) mice. KitW-sh/W-sh mice developed significantly larger skin lesions after the cutaneous S. aureus challenge, when compared to wild-type (WT) mice, while MC dysfunction reduced the inflammation response to S. aureus. The levels of tumor necrosis factor (TNF)-α in skin tissues were significantly decreased in KitW-sh/W-sh mice upon infection. Moreover, the exogenous administration of MCs or recombinant TNF-α effectively restored the immune response against S. aureus in KitW-sh/W-sh mice via the recruitment of neutrophils to the infected site. These results indicate that the effects of MC deficiency are largely attributed to the decrease in production of TNF-α in cutaneous S. aureus infection. In addition, S. aureus-induced MC activation was dependent on the c-kit receptor-activated phosphoinositide 3-kinase (PI3K)/AKT/P65-nuclear factor (NF-κB) pathway, which was confirmed by treatment with Masitinib (a c-kit receptor inhibitor), Wortmannin (a PI3K inhibitor), and pyrrolidine dithiocarbamate (a NF-κB inhibitor), respectively. The present study identifies the critical role of MCs in the host defense against S. aureus infection.

microRNA Response to Listeria monocytogenes Infection in Epithelial Cells

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Izar, Benjamin; Mannala, Gopala Krishna; Mraheil, Mobarak Abu; Chakraborty, Trinad; Hain, Torsten

2012-01-01

microRNAs represent a family of very small non-coding RNAs that control several physiologic and pathologic processes, including host immune response and cancer by antagonizing a number of target mRNAs. There is limited knowledge about cell expression and the regulatory role of microRNAs following bacterial infections. We investigated whether infection with a Gram-positive bacterium leads to altered expression of microRNAs involved in the host cell response in epithelial cells. Caco-2 cells were infected with Listeria monocytogenes EGD-e, a mutant strain (ΔinlAB or Δhly) or incubated with purified listeriolysin (LLO). Total RNA was isolated and microRNA and target gene expression was compared to the expression in non-infected cells using microRNA microarrays and qRT-PCR. We identified and validated five microRNAs (miR- 146b, miR-16, let-7a1, miR-145 and miR-155) that were significantly deregulated following listerial infection. We show that expression patterns of particular microRNAs strongly depend on pathogen localization and the presence of bacterial effector proteins. Strikingly, miR-155 which was shown to have an important role in inflammatory responses during infection was induced by wild-type bacteria, by LLO-deficient bacteria and following incubation with purified LLO. It was downregulated following ΔinlAB infection indicating a new potent role for internalins in listerial pathogenicity and miRNA regulation. Concurrently, we observed differences in target transcript expression of the investigated miRNAs. We provide first evidence that L. monocytogenes infection leads to deregulation of a set of microRNAs with important roles in host response. Distinct microRNA expression depends on both LLO and pathogen localization. PMID:22312311

Glycosylation-related gene expression in HT29-MTX-E12 cells upon infection by Helicobacter pylori.

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Cairns, Michael T; Gupta, Ananya; Naughton, Julie A; Kane, Marian; Clyne, Marguerite; Joshi, Lokesh

2017-10-07

To identify glycosylation-related genes in the HT29 derivative cell line, HT29-MTX-E12, showing differential expression on infection with Helicobacter pylori ( H. pylori ). Polarised HT29-MTX-E12 cells were infected for 24 h with H. pylori strain 26695. After infection RNA was isolated from both infected and non-infected host cells. Sufficient infections were carried out to provide triplicate samples for microarray analysis and for qRT-PCR analysis. RNA was isolated and hybridised to Affymetrix arrays. Analysis of microarray data identified genes significantly differentially expressed upon infection. Genes were grouped into gene ontology functional categories. Selected genes associated with host glycan structure (glycosyltransferases, hydrolases, lectins, mucins) were validated by real-time qRT-PCR analysis. Infection of host cells was confirmed by the isolation of live bacteria after 24 h incubation and by PCR amplification of bacteria-specific genes from the host cell RNA. H. pylori do not survive incubation under the adopted culture conditions unless they associate with the adherent mucus layer of the host cell. Microarray analysis identified a total of 276 genes that were significantly differentially expressed ( P < 0.05) upon H. pylori infection and where the fold change in expression was greater than 2. Six of these genes are involved in glycosylation-related processes. Real-time qRT-PCR demonstrated significant downregulation (1.8-fold, P < 0.05) of the mucin MUC20. REG4 was heavily expressed and significantly downregulated (3.1-fold, P < 0.05) upon infection. Gene ontology analysis was consistent with previous studies on H. pylori infection. Gene expression data suggest that infection with H. pylori causes a decrease in glycan synthesis, resulting in shorter and simpler glycan structures.

Systems Analysis of Early Host Gene Expression Provides Clues for Transient Mycobacterium avium ssp avium vs. Persistent Mycobacterium avium ssp paratuberculosis Intestinal Infections.

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Khare, Sangeeta; Drake, Kenneth L; Lawhon, Sara D; Nunes, Jairo E S; Figueiredo, Josely F; Rossetti, Carlos A; Gull, Tamara; Everts, Robin E; Lewin, Harris A; Adams, Leslie Garry

It has long been a quest in ruminants to understand how two very similar mycobacterial species, Mycobacterium avium ssp. paratuberculosis (MAP) and Mycobacterium avium ssp. avium (MAA) lead to either a chronic persistent infection or a rapid-transient infection, respectively. Here, we hypothesized that when the host immune response is activated by MAP or MAA, the outcome of the infection depends on the early activation of signaling molecules and host temporal gene expression. To test our hypothesis, ligated jejuno-ileal loops including Peyer's patches in neonatal calves were inoculated with PBS, MAP, or MAA. A temporal analysis of the host transcriptome profile was conducted at several times post-infection (0.5, 1, 2, 4, 8 and 12 hours). When comparing the transcriptional responses of calves infected with the MAA versus MAP, discordant patterns of mucosal expression were clearly evident, and the numbers of unique transcripts altered were moderately less for MAA-infected tissue than were mucosal tissues infected with the MAP. To interpret these complex data, changes in the gene expression were further analyzed by dynamic Bayesian analysis. Bayesian network modeling identified mechanistic genes, gene-to-gene relationships, pathways and Gene Ontologies (GO) biological processes that are involved in specific cell activation during infection. MAP and MAA had significant different pathway perturbation at 0.5 and 12 hours post inoculation. Inverse processes were observed between MAP and MAA response for epithelial cell proliferation, negative regulation of chemotaxis, cell-cell adhesion mediated by integrin and regulation of cytokine-mediated signaling. MAP inoculated tissue had significantly lower expression of phagocytosis receptors such as mannose receptor and complement receptors. This study reveals that perturbation of genes and cellular pathways during MAP infection resulted in host evasion by mucosal membrane barrier weakening to access entry in the ileum

Cytokines and the anorexia of infection: potential mechanisms and treatments.

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McCarthy, D O

2000-04-01

Anorexia during infection is thought to be mediated by immunoregulatory cytokines such as interleukins 1 and 6 and tumor necrosis factor. This article reviews the potential mechanisms of action by which these cytokines are thought to suppress food intake during infection and examines the proposition that blocking of cytokine activity might be one approach to improving food intake of the infected host.

In vitro studies of Rickettsia-host cell interactions: Confocal laser scanning microscopy of Rickettsia helvetica-infected eukaryotic cell lines.

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Speck, Stephanie; Kern, Tanja; Aistleitner, Karin; Dilcher, Meik; Dobler, Gerhard; Essbauer, Sandra

2018-02-01

Rickettsia (R.) helvetica is the most prevalent rickettsia found in Ixodes ricinus ticks in Germany. Several studies reported antibodies against R. helvetica up to 12.5% in humans investigated, however, fulminant clinical cases are rare indicating a rather low pathogenicity compared to other rickettsiae. We investigated growth characteristics of R. helvetica isolate AS819 in two different eukaryotic cell lines with focus on ultra-structural changes of host cells during infection determined by confocal laser scanning microscopy. Further investigations included partially sequencing of rickA, sca4 and sca2 genes, which have been reported to encode proteins involved in cell-to-cell spread and virulence in some rickettsiae. R. helvetica grew constantly but slowly in both cell lines used. Confocal laser scanning microscopy revealed that the dissemination of R. helvetica AS819 in both cell lines was rather mediated by cell break-down and bacterial release than cell-to-cell spread. The cytoskeleton of both investigated eukaryotic cell lines was not altered. R. helvetica possesses rickA, but its expression is not sufficient to promote actin-based motility as demonstrated by confocal laser scanning microscopy. Hypothetical Sca2 and Sca4 proteins were deduced from nucleotide gene sequences but the predicted amino acid sequences were disrupted or truncated compared to other rickettsiae most likely resulting in non-functional proteins. Taken together, these results might give a first hint to the underlying causes of the reduced virulence and pathogenicity of R. helvetica.

Transcriptome analysis reveals the host response to Schmallenberg virus in bovine cells and antagonistic effects of the NSs protein.

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Blomström, Anne-Lie; Gu, Quan; Barry, Gerald; Wilkie, Gavin; Skelton, Jessica K; Baird, Margaret; McFarlane, Melanie; Schnettler, Esther; Elliott, Richard M; Palmarini, Massimo; Kohl, Alain

2015-04-19

Schmallenberg virus (SBV) is a member of the Orthobunyavirus genus (Bunyaviridae family) causing malformations and abortions in ruminants. Although, as for other members of this family/genus, the non-structural protein NSs has been shown to be an interferon antagonist, very little is known regarding the overall inhibitory effects and targets of orthobunyavirus NSs proteins on host gene expression during infection. Therefore, using RNA-seq this study describes changes to the transcriptome of primary bovine cells following infection with Schmallenberg virus (SBV) or with a mutant lacking the non-structural protein NSs (SBVdelNSs) providing a detailed comparison of the effect of NSs expression on the host cell. The sequence reads from all samples (uninfected cells, SBV and SBVdelNSs) assembled well to the bovine host reference genome (on average 87.43% of the reads). During infection with SBVdelNSs, 649 genes were differentially expressed compared to uninfected cells (78.7% upregulated) and many of these were known antiviral and IFN-stimulated genes. On the other hand, only nine genes were differentially expressed in SBV infected cells compared to uninfected control cells, demonstrating the strong inhibitory effect of NSs on cellular gene expression. However, the majority of the genes that were expressed during SBV infection are involved in restriction of viral replication and spread indicating that SBV does not completely manage to shutdown the host antiviral response. In this study we show the effects of SBV NSs on the transcriptome of infected cells as well as the cellular response to wild type SBV. Although NSs is very efficient in shutting down genes of the host innate response, a number of possible antiviral factors were identified. Thus the data from this study can serve as a base for more detailed mechanistic studies of SBV and other orthobunyaviruses.

Salmonella enterica serovar-specific transcriptional reprogramming of infected cells.

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Hannemann, Sebastian; Galán, Jorge E

2017-07-01

Despite their high degree of genomic similarity, different Salmonella enterica serovars are often associated with very different clinical presentations. In humans, for example, the typhoidal S. enterica serovar Typhi causes typhoid fever, a life-threatening systemic disease. In contrast, the non-typhoidal S. enterica serovar Typhimurium causes self-limiting gastroenteritis. The molecular bases for these different clinical presentations are incompletely understood. The ability to re-program gene expression in host cells is an essential virulence factor for typhoidal and non-typhoidal S. enterica serovars. Here, we have compared the transcriptional profile of cultured epithelial cells infected with S. Typhimurium or S. Typhi. We found that both serovars stimulated distinct transcriptional responses in infected cells that are associated with the stimulation of specific signal transduction pathways. These specific responses were associated with the presence of a distinct repertoire of type III secretion effector proteins. These observations provide major insight into the molecular bases for potential differences in the pathogenic mechanisms of typhoidal and non-typhoidal S. enterica serovars.

Mechanisms of Disease: Host-Pathogen Interactions between Burkholderia Species and Lung Epithelial Cells

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David, Jonathan; Bell, Rachel E.; Clark, Graeme C.

2015-01-01

Members of the Burkholderia species can cause a range of severe, often fatal, respiratory diseases. A variety of in vitro models of infection have been developed in an attempt to elucidate the mechanism by which Burkholderia spp. gain entry to and interact with the body. The majority of studies have tended to focus on the interaction of bacteria with phagocytic cells with a paucity of information available with regard to the lung epithelium. However, the lung epithelium is becoming more widely recognized as an important player in innate immunity and the early response to infections. Here we review the complex relationship between Burkholderia species and epithelial cells with an emphasis on the most pathogenic species, Burkholderia pseudomallei and Burkholderia mallei. The current gaps in knowledge in our understanding are highlighted along with the epithelial host-pathogen interactions that offer potential opportunities for therapeutic intervention. PMID:26636042

Pathogenesis and host response in Syrian hamsters following intranasal infection with Andes virus.

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David Safronetz

2011-12-01

Full Text Available Hantavirus pulmonary syndrome (HPS, also referred to as hantavirus cardiopulmonary syndrome (HCPS, is a rare but frequently fatal disease caused by New World hantaviruses. In humans HPS is associated with severe pulmonary edema and cardiogenic shock; however, the pathogenesis of this disease remains unclear largely due to a lack of suitable animal models for the study of disease progression. In this study we monitored clinical, virological, pathophysiological parameters and host immunological responses to decipher pathological factors and events in the lethal Syrian hamster model of HPS following intranasal inoculation of Andes virus. Transcriptional profiling of the host gene responses demonstrated a suppression of innate immune responses in most organs analyzed during the early stage of infection, except for in the lung which had low level activation of several pro-inflammatory genes. During this phase Andes virus established a systemic infection in hamsters, with viral antigen readily detectable in the endothelium of the majority of tissues analyzed by 7-8 days post-inoculation. Despite wide-spread infection, histological analysis confirmed pathological abnormalities were almost exclusively found in the lungs. Immediately preceding clinical signs of disease, intense activation of pro-inflammatory and Th1/Th2 responses were observed in the lungs as well as the heart, but not in peripheral organs, suggesting that localized immune-modulations by infection is paramount to pathogenesis. Throughout the course of infection a strong suppression of regulatory T-cell responses was noted and is hypothesized to be the basis of the aberrant immune activations. The unique and comprehensive monitoring of host immune responses to hantavirus infection increases our understanding of the immuno-pathogenesis of HPS and will facilitate the development of treatment strategies targeting deleterious host immunological responses.

Isolation and Host Range of Bacteriophage with Lytic Activity against Methicillin-Resistant Staphylococcus aureus and Potential Use as a Fomite Decontaminant.

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Kyle C Jensen

Full Text Available Staphylococcus aureus (SA is a commensal bacterium and opportunistic pathogen commonly associated with humans and is capable of causing serious disease and death including sepsis, pneumonia, and meningitis. Methicillin-resistant SA (MRSA isolates are typically resistant to many available antibiotics with the common exception of vancomycin. The presence of vancomycin resistance in some SA isolates combined with the current heavy use of vancomycin to treat MRSA infections indicates that MRSA may achieve broad resistance to vancomycin in the near future. New MRSA treatments are clearly needed. Bacteriophages (phages are viruses that infect bacteria, commonly resulting in death of the host bacterial cell. Phage therapy entails the use of phage to treat or prevent bacterial infections. In this study, 12 phages were isolated that can replicate in human SA and/or MRSA isolates as a potential way to control these infections. 5 phage were discovered through mitomycin C induction of prophage and 7 others as extracellular viruses. Primary SA strains were also isolated from environmental sources to be used as tools for phage discovery and isolation as well as to examine the target cell host range of the phage isolates by spot testing. Primary isolates were tested for susceptibility to oxacillin in order to determine which were MRSA. Experiments were performed to assess the host range and killing potential of newly discovered phage, and significant reductions in bacterial load were detected. We explored the utility of some phage to decontaminate fomites (glass and cloth and found a significant reduction in colony forming units of MRSA following phage treatment, including tests of a phage cocktail against a cocktail of MRSA isolates. Our findings suggest that phage treatment can be used as an effective tool to decontaminate human MRSA from both hard surfaces and fabrics.

Enhanced capacity of DNA repair in human cytomegalovirus-infected cells

International Nuclear Information System (INIS)

Nishiyama, Y.; Rapp, F.

1981-01-01

Plaque formation in Vero cells by UV-irradiated herpes simplex virus was enhanced by infection with human cytomegalovirus (HCMV), UV irradiation, or treatment with methylmethanesulfonate. Preinfection of Vero cells with HCMV enhanced reactivation of UV-irradiated herpes simplex virus more significantly than did treatment with UV or methylmethanesulfonate alone. A similar enhancement by HCMV was observed in human embryonic fibroblasts, but not in xeroderma pigmentosum (XP12BE) cells. It was also found that HCMV infection enhanced hydroxyurea-resistant DNA synthesis induced by UV light or methylmethanesulfonate. Alkaline sucrose gradient sedimentation analysis revealed an enhanced rate of synthesis of all size classes of DNA in UV-irradiated HCMV-infected Vero cells. However, HCMV infection did not induce repairable lesions in cellular DNA and did not significantly inhibit host cell DNA synthesis, unlike UV or methylmethanesulfonate. These results indicate that HCMV enhanced DNA repair capacity in the host cells without producing detectable lesions in cellular DNA and without inhibiting DNA synthesis. This repair appeared to be error proof for UV-damaged herpes simplex virus DNA when tested with herpes simplex virus thymidine kinase-negative mutants

Real-time whole-body visualization of Chikungunya Virus infection and host interferon response in zebrafish.

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Nuno Palha

Full Text Available Chikungunya Virus (CHIKV, a re-emerging arbovirus that may cause severe disease, constitutes an important public health problem. Herein we describe a novel CHIKV infection model in zebrafish, where viral spread was live-imaged in the whole body up to cellular resolution. Infected cells emerged in various organs in one principal wave with a median appearance time of ∼14 hours post infection. Timing of infected cell death was organ dependent, leading to a shift of CHIKV localization towards the brain. As in mammals, CHIKV infection triggered a strong type-I interferon (IFN response, critical for survival. IFN was mainly expressed by neutrophils and hepatocytes. Cell type specific ablation experiments further demonstrated that neutrophils play a crucial, unexpected role in CHIKV containment. Altogether, our results show that the zebrafish represents a novel valuable model to dynamically visualize replication, pathogenesis and host responses to a human virus.

Host cell tropism mediated by Australian bat lyssavirus envelope glycoproteins.

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Weir, Dawn L; Smith, Ina L; Bossart, Katharine N; Wang, Lin-Fa; Broder, Christopher C

2013-09-01

Australian bat lyssavirus (ABLV) is a rhabdovirus of the lyssavirus genus capable of causing fatal rabies-like encephalitis in humans. There are two variants of ABLV, one circulating in pteropid fruit bats and another in insectivorous bats. Three fatal human cases of ABLV infection have been reported with the third case in 2013. Importantly, two equine cases also arose in 2013; the first occurrence of ABLV in a species other than bats or humans. We examined the host cell entry of ABLV, characterizing its tropism and exploring its cross-species transmission potential using maxGFP-encoding recombinant vesicular stomatitis viruses that express ABLV G glycoproteins. Results indicate that the ABLV receptor(s) is conserved but not ubiquitous among mammalian cell lines and that the two ABLV variants can utilize alternate receptors for entry. Proposed rabies virus receptors were not sufficient to permit ABLV entry into resistant cells, suggesting that ABLV utilizes an unknown alternative receptor(s). Published by Elsevier Inc.

Porphyromonas gingivalis as a Model Organism for Assessing Interaction of Anaerobic Bacteria with Host Cells.

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Wunsch, Christopher M; Lewis, Janina P

2015-12-17

Anaerobic bacteria far outnumber aerobes in many human niches such as the gut, mouth, and vagina. Furthermore, anaerobic infections are common and frequently of indigenous origin. The ability of some anaerobic pathogens to invade human cells gives them adaptive measures to escape innate immunity as well as to modulate host cell behavior. However, ensuring that the anaerobic bacteria are live during experimental investigation of the events may pose challenges. Porphyromonas gingivalis, a Gram-negative anaerobe, is capable of invading a variety of eukaryotic non-phagocytic cells. This article outlines how to successfully culture and assess the ability of P. gingivalis to invade human umbilical vein endothelial cells (HUVECs). Two protocols were developed: one to measure bacteria that can successfully invade and survive within the host, and the other to visualize bacteria interacting with host cells. These techniques necessitate the use of an anaerobic chamber to supply P. gingivalis with an anaerobic environment for optimal growth. The first protocol is based on the antibiotic protection assay, which is largely used to study the invasion of host cells by bacteria. However, the antibiotic protection assay is limited; only intracellular bacteria that are culturable following antibiotic treatment and host cell lysis are measured. To assess all bacteria interacting with host cells, both live and dead, we developed a protocol that uses fluorescent microscopy to examine host-pathogen interaction. Bacteria are fluorescently labeled with 2',7'-Bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF-AM) and used to infect eukaryotic cells under anaerobic conditions. Following fixing with paraformaldehyde and permeabilization with 0.2% Triton X-100, host cells are labeled with TRITC phalloidin and DAPI to label the cell cytoskeleton and nucleus, respectively. Multiple images taken at different focal points (Z-stack) are obtained for temporal

A novel host-proteome signature for distinguishing between acute bacterial and viral infections.

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Kfir Oved

Full Text Available Bacterial and viral infections are often clinically indistinguishable, leading to inappropriate patient management and antibiotic misuse. Bacterial-induced host proteins such as procalcitonin, C-reactive protein (CRP, and Interleukin-6, are routinely used to support diagnosis of infection. However, their performance is negatively affected by inter-patient variability, including time from symptom onset, clinical syndrome, and pathogens. Our aim was to identify novel viral-induced host proteins that can complement bacterial-induced proteins to increase diagnostic accuracy. Initially, we conducted a bioinformatic screen to identify putative circulating host immune response proteins. The resulting 600 candidates were then quantitatively screened for diagnostic potential using blood samples from 1002 prospectively recruited patients with suspected acute infectious disease and controls with no apparent infection. For each patient, three independent physicians assigned a diagnosis based on comprehensive clinical and laboratory investigation including PCR for 21 pathogens yielding 319 bacterial, 334 viral, 112 control and 98 indeterminate diagnoses; 139 patients were excluded based on predetermined criteria. The best performing host-protein was TNF-related apoptosis-inducing ligand (TRAIL (area under the curve [AUC] of 0.89; 95% confidence interval [CI], 0.86 to 0.91, which was consistently up-regulated in viral infected patients. We further developed a multi-protein signature using logistic-regression on half of the patients and validated it on the remaining half. The signature with the highest precision included both viral- and bacterial-induced proteins: TRAIL, Interferon gamma-induced protein-10, and CRP (AUC of 0.94; 95% CI, 0.92 to 0.96. The signature was superior to any of the individual proteins (P<0.001, as well as routinely used clinical parameters and their combinations (P<0.001. It remained robust across different physiological systems

Genetic-and-epigenetic Interspecies Networks for Cross-talk Mechanisms in Human Macrophages and Dendritic Cells During MTB Infection

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Cheng-Wei Li

2016-10-01

Full Text Available Tuberculosis is caused by Mycobacterium tuberculosis (Mtb infection. Mtb is one of the oldest human pathogens, and evolves mechanisms implied in human evolution. The lungs are the first organ exposed to aerosol-transmitted Mtb during gaseous exchange. Therefore, the guards of the immune system in the lungs, such as macrophages (Mϕs and dendritic cells (DCs, are the most important defense against Mtb infection. There have been several studies discussing the functions of Mϕs and DCs during Mtb infection, but the genome-wide pathways and networks are still incomplete. Furthermore, the immune response induced by Mϕs and DCs varies. Therefore, we analyzed the cross-talk genome-wide genetic-and-epigenetic interspecies networks (GWGEINs between Mϕs vs. Mtb and DCs vs. Mtb to determine the varying mechanisms of both the host and pathogen as it relates to Mϕs and DCs during early Mtb infection.First, we performed database mining to construct candidate cross-talk GWGEIN between human cells and Mtb. Then we constructed dynamic models to characterize the molecular mechanisms, including intraspecies gene/microRNA (miRNA regulation networks (GRNs, intraspecies protein-protein interaction networks (PPINs, and the interspecies PPIN of the cross-talk GWGEIN. We applied a system identification method and a system order detection scheme to dynamic models to identify the real cross-talk GWGEINs using the microarray data of Mϕs, DCs and Mtb.After identifying the real cross-talk GWGEINs, the principal network projection (PNP method was employed to construct host-pathogen core networks (HPCNs between Mϕs vs. Mtb and DCs vs. Mtb during infection process. Thus, we investigated the underlying cross-talk mechanisms between the host and the pathogen to determine how the pathogen counteracts host defense mechanisms in Mϕs and DCs during Mtb H37Rv early infection. Based on our findings, we propose Rv1675c as a potential drug target because of its important defensive

Proteome data from a host-pathogen interaction study with Staphylococcus aureus and human lung epithelial cells

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Kristin Surmann

2016-06-01

Full Text Available To simultaneously obtain proteome data of host and pathogen from an internalization experiment, human alveolar epithelial A549 cells were infected with Staphylococcus aureus HG001 which carried a plasmid (pMV158GFP encoding a continuously expressed green fluorescent protein (GFP. Samples were taken hourly between 1.5 h and 6.5 h post infection. By fluorescence activated cell sorting GFP-expressing bacteria could be enriched from host cell debris, but also infected host cells could be separated from those which did not carry bacteria after contact (exposed. Additionally, proteome data of A549 cells which were not exposed to S. aureus but underwent the same sample processing steps are provided as a control. Time-resolved changes in bacterial protein abundance were quantified in a label-free approach. Proteome adaptations of host cells were monitored by comparative analysis to a stable isotope labeled cell culture (SILAC standard. Proteins were extracted from the cells, digested proteolytically, measured by nanoLC–MS/MS, and subsequently identified by database search and then quantified. The data presented here are related to a previously published research article describing the interplay of S. aureus HG001 and human epithelial cells (Surmann et al., 2015 [1]. They have been deposited to the ProteomeXchange platform with the identifiers PRIDE: http://www.ebi.ac.uk/pride/archive/projects/PXD002384 for the S. aureus HG001 proteome dataset and PRIDE: http://www.ebi.ac.uk/pride/archive/projects/PXD002388 for the A549 proteome dataset.

Cytoarchitecture of Zika virus infection in human neuroblastoma and Aedes albopictus cell lines.

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Offerdahl, Danielle K; Dorward, David W; Hansen, Bryan T; Bloom, Marshall E

2017-01-15

The Zika virus (ZIKV) pandemic is a global concern due to its role in the development of congenital anomalies of the central nervous system. This mosquito-borne flavivirus alternates between mammalian and mosquito hosts, but information about the biogenesis of ZIKV is limited. Using a human neuroblastoma cell line (SK-N-SH) and an Aedes albopictus mosquito cell line (C6/36), we characterized ZIKV infection by immunofluorescence, transmission electron microscopy (TEM), and electron tomography (ET) to better understand infection in these disparate host cells. ZIKV replicated well in both cell lines, but infected SK-N-SH cells suffered a lytic crisis. Flaviviruses scavenge host cell membranes to serve as replication platforms and ZIKV showed the hallmarks of this process. Via TEM, we identified virus particles and 60-100nm spherular vesicles. ET revealed these vesicular replication compartments contain smaller 20-30nm spherular structures. Our studies indicate that SK-N-SH and C6/36 cells are relevant models for viral cytoarchitecture study. Published by Elsevier Inc.

Mycobacterium tuberculosis infection induces non-apoptotic cell death of human dendritic cells

LENUS (Irish Health Repository)

Ryan, Ruth CM

2011-10-24

Abstract Background Dendritic cells (DCs) connect innate and adaptive immunity, and are necessary for an efficient CD4+ and CD8+ T cell response after infection with Mycobacterium tuberculosis (Mtb). We previously described the macrophage cell death response to Mtb infection. To investigate the effect of Mtb infection on human DC viability, we infected these phagocytes with different strains of Mtb and assessed viability, as well as DNA fragmentation and caspase activity. In parallel studies, we assessed the impact of infection on DC maturation, cytokine production and bacillary survival. Results Infection of DCs with live Mtb (H37Ra or H37Rv) led to cell death. This cell death proceeded in a caspase-independent manner, and without nuclear fragmentation. In fact, substrate assays demonstrated that Mtb H37Ra-induced cell death progressed without the activation of the executioner caspases, 3\\/7. Although the death pathway was triggered after infection, the DCs successfully underwent maturation and produced a host-protective cytokine profile. Finally, dying infected DCs were permissive for Mtb H37Ra growth. Conclusions Human DCs undergo cell death after infection with live Mtb, in a manner that does not involve executioner caspases, and results in no mycobactericidal effect. Nonetheless, the DC maturation and cytokine profile observed suggests that the infected cells can still contribute to TB immunity.

Proteomic Analysis of Rhizoctonia solani Identifies Infection-specific, Redox Associated Proteins and Insight into Adaptation to Different Plant Hosts*

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Anderson, Jonathan P.; Hane, James K.; Stoll, Thomas; Pain, Nicholas; Hastie, Marcus L.; Kaur, Parwinder; Hoogland, Christine; Gorman, Jeffrey J.; Singh, Karam B.

2016-01-01

Rhizoctonia solani is an important root infecting pathogen of a range of food staples worldwide including wheat, rice, maize, soybean, potato and others. Conventional resistance breeding strategies are hindered by the absence of tractable genetic resistance in any crop host. Understanding the biology and pathogenicity mechanisms of this fungus is important for addressing these disease issues, however, little is known about how R. solani causes disease. This study capitalizes on recent genomic studies by applying mass spectrometry based proteomics to identify soluble, membrane-bound and culture filtrate proteins produced under wheat infection and vegetative growth conditions. Many of the proteins found in the culture filtrate had predicted functions relating to modification of the plant cell wall, a major activity required for pathogenesis on the plant host, including a number found only under infection conditions. Other infection related proteins included a high proportion of proteins with redox associated functions and many novel proteins without functional classification. The majority of infection only proteins tested were confirmed to show transcript up-regulation during infection including a thaumatin which increased susceptibility to R. solani when expressed in Nicotiana benthamiana. In addition, analysis of expression during infection of different plant hosts highlighted how the infection strategy of this broad host range pathogen can be adapted to the particular host being encountered. Data are available via ProteomeXchange with identifier PXD002806. PMID:26811357

Lymphotropism and host responses during acute wild-type canine distemper virus infections in a highly susceptible natural host

DEFF Research Database (Denmark)

Nielsen, Line; Søgaard, Mette; Jensen, Trine Hammer

2009-01-01

The mechanisms behind the in vivo virulence of immunosuppressive wild-type Morbillivirus infections are still not fully understood. To investigate lymphotropism and host responses we have selected the natural host model of canine distemper virus (CDV) infection in mink. This model displays...

Host genetic variation influences gene expression response to rhinovirus infection.

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Minal Çalışkan

2015-04-01

Full Text Available Rhinovirus (RV is the most prevalent human respiratory virus and is responsible for at least half of all common colds. RV infections may result in a broad spectrum of effects that range from asymptomatic infections to severe lower respiratory illnesses. The basis for inter-individual variation in the response to RV infection is not well understood. In this study, we explored whether host genetic variation is associated with variation in gene expression response to RV infections between individuals. To do so, we obtained genome-wide genotype and gene expression data in uninfected and RV-infected peripheral blood mononuclear cells (PBMCs from 98 individuals. We mapped local and distant genetic variation that is associated with inter-individual differences in gene expression levels (eQTLs in both uninfected and RV-infected cells. We focused specifically on response eQTLs (reQTLs, namely, genetic associations with inter-individual variation in gene expression response to RV infection. We identified local reQTLs for 38 genes, including genes with known functions in viral response (UBA7, OAS1, IRF5 and genes that have been associated with immune and RV-related diseases (e.g., ITGA2, MSR1, GSTM3. The putative regulatory regions of genes with reQTLs were enriched for binding sites of virus-activated STAT2, highlighting the role of condition-specific transcription factors in genotype-by-environment interactions. Overall, we suggest that the 38 loci associated with inter-individual variation in gene expression response to RV-infection represent promising candidates for affecting immune and RV-related respiratory diseases.

Host genetic variation influences gene expression response to rhinovirus infection.

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Çalışkan, Minal; Baker, Samuel W; Gilad, Yoav; Ober, Carole

2015-04-01

Rhinovirus (RV) is the most prevalent human respiratory virus and is responsible for at least half of all common colds. RV infections may result in a broad spectrum of effects that range from asymptomatic infections to severe lower respiratory illnesses. The basis for inter-individual variation in the response to RV infection is not well understood. In this study, we explored whether host genetic variation is associated with variation in gene expression response to RV infections between individuals. To do so, we obtained genome-wide genotype and gene expression data in uninfected and RV-infected peripheral blood mononuclear cells (PBMCs) from 98 individuals. We mapped local and distant genetic variation that is associated with inter-individual differences in gene expression levels (eQTLs) in both uninfected and RV-infected cells. We focused specifically on response eQTLs (reQTLs), namely, genetic associations with inter-individual variation in gene expression response to RV infection. We identified local reQTLs for 38 genes, including genes with known functions in viral response (UBA7, OAS1, IRF5) and genes that have been associated with immune and RV-related diseases (e.g., ITGA2, MSR1, GSTM3). The putative regulatory regions of genes with reQTLs were enriched for binding sites of virus-activated STAT2, highlighting the role of condition-specific transcription factors in genotype-by-environment interactions. Overall, we suggest that the 38 loci associated with inter-individual variation in gene expression response to RV-infection represent promising candidates for affecting immune and RV-related respiratory diseases.

In vivo Host Environment Alters Pseudomonas aeruginosa Susceptibility to Aminoglycoside Antibiotics

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Pan, Xiaolei; Dong, Yuanyuan; Fan, Zheng; Liu, Chang; Xia, Bin; Shi, Jing; Bai, Fang; Jin, Yongxin; Cheng, Zhihui; Jin, Shouguang; Wu, Weihui

2017-01-01

During host infection, Pseudomonas aeruginosa coordinately regulates the expression of numerous genes to adapt to the host environment while counteracting host clearance mechanisms. As infected patients take antibiotics, the invading bacteria encounter antibiotics in the host milieu. P. aeruginosa is highly resistant to antibiotics due to multiple chromosomally encoded resistant determinants. And numerous in vitro studies have demonstrated the regulatory mechanisms of antibiotic resistance related genes in response to antibiotics. However, it is not well-known how host environment affects bacterial response to antibiotics. In this study, we found that P. aeruginosa cells directly isolated from mice lungs displayed higher susceptibility to tobramycin than in vitro cultured bacteria. In vitro experiments demonstrated that incubation with A549 and differentiated HL60 (dHL60) cells sensitized P. aeruginosa to tobramycin. Further studies revealed that reactive oxygen species produced by the host cells contributed to the increased bacterial susceptibility. At the same concentration of tobramycin, presence of A549 and dHL60 cells resulted in higher expression of heat shock proteins, which are known inducible by tobramycin. Further analyses revealed decreased membrane potential upon incubation with the host cells and modification of lipopolysaccharide, which contributed to the increased susceptibility to tobramycin. Therefore, our results demonstrate that contact with host cells increased bacterial susceptibility to tobramycin. PMID:28352614

A mathematical modelling framework for linked within-host and between-host dynamics for infections with free-living pathogens in the environment.

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Garira, Winston; Mathebula, Dephney; Netshikweta, Rendani

2014-10-01

In this study we develop a mathematical modelling framework for linking the within-host and between-host dynamics of infections with free-living pathogens in the environment. The resulting linked models are sometimes called immuno-epidemiological models. However, there is still no generalised framework for linking the within-host and between-host dynamics of infectious diseases. Furthermore, for infections with free-living pathogens in the environment, there is an additional stumbling block in that there is a gap in knowledge on how environmental factors (through water, air, soil, food, fomites, etc.) alter many aspects of such infections including susceptibility to infective dose, persistence of infection, pathogen shedding and severity of the disease. In this work, we link the two subsystems (within-host and between-host models) by identifying the within-host and between-host variables and parameters associated with the environmental dynamics of the pathogen and then design a feedback of the variables and parameters across the within-host and between-host models using human schistosomiasis as a case study. We study the mathematical properties of the linked model and show that the model is epidemiologically well-posed. Using results from the analysis of the endemic equilibrium expression, the disease reproductive number R0, and numerical simulations of the full model, we adequately account for the reciprocal influence of the linked within-host and between-host models. In particular, we illustrate that for human schistosomiasis, the outcome of infection at the individual level determines if, when and how much the individual host will further transmit the infectious agent into the environment, eventually affecting the spread of the infection in the host population. We expect the conceptual modelling framework developed here to be applicable to many infectious disease with free-living pathogens in the environment beyond the specific disease system of human

Host cell reactivation of uv- and X-ray-damaged herpes simplex virus by Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines

International Nuclear Information System (INIS)

Henderson, E.E.; Long, W.K.

1981-01-01

The efficacy of using an infected centers assay, employing herpes simplex virus-infected, Epstein-Barr virus-transformed lymphoblastoid cell lines (LCLs) as components, to study host cell reactivation has been explored. Herpes simplex virus type 1 (HSV-1) was shown through the infected centers assay to have detectable but varying ability to lytically infect LCLs established from chromosomal breakage syndromes or closely related genetic disorders. The rate of HSV inactivation by ultraviolet (uv) irradiation was faster in LCLs established from Cockaynes's syndrome than in normal LCLs, and faster still in LCLs established from xeroderma pigmentosum. These results indicate that Cockayne's syndrome, while having what appears to be quantitatively normal levels of uv-induced DNA repair replication, shows decreased ability to host cell reactivated uv-damaged HSV. In direct contrast, X-irradiated HSV showed identical survival when assayed on normal LCLs or LCLs established from ataxia telangiectasia showing increased sensitivity to X irradiation as measured by colony formation. Through the infected centers assay, it has also been possible to demonstrate low levels of multiplicity reactivation of mutagen-damaged HSV in permanently proliferating LCLs

Melaleuca alternifolia Concentrate Inhibits in Vitro Entry of Influenza Virus into Host Cells

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Lifang Jiang

2013-08-01

Full Text Available Influenza virus causes high morbidity among the infected population annually and occasionally the spread of pandemics. Melaleuca alternifolia Concentrate (MAC is an essential oil derived from a native Australian tea tree. Our aim was to investigate whether MAC has any in vitro inhibitory effect on influenza virus infection and what mechanism does the MAC use to fight the virus infection. In this study, the antiviral activity of MAC was examined by its inhibition of cytopathic effects. In silico prediction was performed to evaluate the interaction between MAC and the viral haemagglutinin. We found that when the influenza virus was incubated with 0.010% MAC for one hour, no cytopathic effect on MDCK cells was found after the virus infection and no immunofluorescence signal was detected in the host cells. Electron microscopy showed that the virus treated with MAC retained its structural integrity. By computational simulations, we found that terpinen-4-ol, which is the major bioactive component of MAC, could combine with the membrane fusion site of haemagglutinin. Thus, we proved that MAC could prevent influenza virus from entering the host cells by disturbing the normal viral membrane fusion procedure.

Impact of Childhood Malnutrition on Host Defense and Infection.

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Ibrahim, Marwa K; Zambruni, Mara; Melby, Christopher L; Melby, Peter C

2017-10-01

The global impact of childhood malnutrition is staggering. The synergism between malnutrition and infection contributes substantially to childhood morbidity and mortality. Anthropometric indicators of malnutrition are associated with the increased risk and severity of infections caused by many pathogens, including viruses, bacteria, protozoa, and helminths. Since childhood malnutrition commonly involves the inadequate intake of protein and calories, with superimposed micronutrient deficiencies, the causal factors involved in impaired host defense are usually not defined. This review focuses on literature related to impaired host defense and the risk of infection in primary childhood malnutrition. Particular attention is given to longitudinal and prospective cohort human studies and studies of experimental animal models that address causal, mechanistic relationships between malnutrition and host defense. Protein and micronutrient deficiencies impact the hematopoietic and lymphoid organs and compromise both innate and adaptive immune functions. Malnutrition-related changes in intestinal microbiota contribute to growth faltering and dysregulated inflammation and immune function. Although substantial progress has been made in understanding the malnutrition-infection synergism, critical gaps in our understanding remain. We highlight the need for mechanistic studies that can lead to targeted interventions to improve host defense and reduce the morbidity and mortality of infectious diseases in this vulnerable population. Copyright © 2017 American Society for Microbiology.

Dendritic Cells Activate and Mature after Infection with Mycobacterium tuberculosis

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Mamo Gezahagne

2011-07-01

Full Text Available Abstract Background Dendritic cells (DCs can take up an array of different antigens, including microorganisms which they can process and present more effectively than any other antigen presenting cell. However, whether the interaction between the human DC and Mycobacterium tuberculosis represents a defense mechanism by the invaded host, or helping the invader to evade the defense mechanism of the host is still not clearly understood. Findings To analyze the interactions between M. tuberculosis and immune cells, human peripheral blood monocyte-derived immature DCs were infected with M. tuberculosis H37Rv wild type strain and flow cytometry was used to analyse cell surface expression markers. The ability of the M. tuberculosis infected DC to induce T cell proliferation using 5 and 6-carboxyfluorescein diacetate succinimidyl ester (CFSE dilution technique was also investigated. DCs were found to internalize the mycobacteria and show dose dependent infection and necrosis with different multiplicity of infection. Flow cytometry analysis of cell surface expression markers CD40, CD54, CD80, CD83, CD86 and HLA DR in infected DC revealed significant (p M. tuberculosis in comparison to immature DC with no stimulation. Lipopolysaccharide (LPS from Salmonella abortus equi, a known DC maturation agent, was used as a positive control and showed a comparable up regulation of cell surface markers as observed with M. tuberculosis infected DC. It was revealed that the M. tuberculosis infected DC induced T cell proliferation. Conclusion These data clearly demonstrate that M. tuberculosis induces activation and maturation of human monocyte-derived immature DC as well as induces T cell proliferation in vitro.

Mistletoe infection alters the transpiration flow path and suppresses water regulation of host trees during extreme events

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Griebel, A.; Maier, C.; Barton, C. V.; Metzen, D.; Renchon, A.; Boer, M. M.; Pendall, E.

2017-12-01

Mistletoe is a globally distributed group of parasitic plants that infiltrates the vascular tissue of its host trees to acquire water, carbon and nutrients, making it a leading agent of biotic disturbance. Many mistletoes occur in water-limited ecosystems, thus mistletoe infection in combination with increased climatic stress may exacerbate water stress and potentially accelerate mortality rates of infected trees during extreme events. This is an emerging problem in Australia, as mistletoe distribution is increasing and clear links between mistletoe infection and mortality have been established. However, direct observations about how mistletoes alter host physiological processes during extreme events are rare, which impedes our understanding of mechanisms underlying increased tree mortality rates. We addressed this gap by continuously monitoring stem and branch sap flow and a range of leaf traits of infected and uninfected trees of two co-occurring eucalypt species during a severe heatwave in south-eastern Australia. We demonstrate that mistletoes' leaf water potentials were maintained 30% lower than hosts' to redirect the trees' transpiration flow path towards mistletoe leaves. Eucalypt leaves reduced water loss through stomatal regulation when atmospheric dryness exceeded 2 kPa, but the magnitude of stomatal regulation in non-infected eucalypts differed by species (between 40-80%). Remarkably, when infected, sap flow rates of stems and branches of both eucalypt species remained unregulated even under extreme atmospheric dryness (>8 kPa). Our observations indicate that excessive water use of mistletoes likely increases xylem cavitation rates in hosts during prolonged droughts and supports that hydraulic failure contributes to increased mortality of infected trees. Hence, in order to accurately model the contribution of biotic disturbances to tree mortality under a changing climate, it will be crucial to increase our process-based understanding of the interaction

Role of natural killer cells in innate protection against lethal ebola virus infection.

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Warfield, Kelly L; Perkins, Jeremy G; Swenson, Dana L; Deal, Emily M; Bosio, Catharine M; Aman, M Javad; Yokoyama, Wayne M; Young, Howard A; Bavari, Sina

2004-07-19

Ebola virus is a highly lethal human pathogen and is rapidly driving many wild primate populations toward extinction. Several lines of evidence suggest that innate, nonspecific host factors are potentially critical for survival after Ebola virus infection. Here, we show that nonreplicating Ebola virus-like particles (VLPs), containing the glycoprotein (GP) and matrix protein virus protein (VP)40, administered 1-3 d before Ebola virus infection rapidly induced protective immunity. VLP injection enhanced the numbers of natural killer (NK) cells in lymphoid tissues. In contrast to live Ebola virus, VLP treatment of NK cells enhanced cytokine secretion and cytolytic activity against NK-sensitive targets. Unlike wild-type mice, treatment of NK-deficient or -depleted mice with VLPs had no protective effect against Ebola virus infection and NK cells treated with VLPs protected against Ebola virus infection when adoptively transferred to naive mice. The mechanism of NK cell-mediated protection clearly depended on perforin, but not interferon-gamma secretion. Particles containing only VP40 were sufficient to induce NK cell responses and provide protection from infection in the absence of the viral GP. These findings revealed a decisive role for NK cells during lethal Ebola virus infection. This work should open new doors for better understanding of Ebola virus pathogenesis and direct the development of immunotherapeutics, which target the innate immune system, for treatment of Ebola virus infection.

Early host responses of seasonal and pandemic influenza A viruses in primary well-differentiated human lung epithelial cells.

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Rachael L Gerlach

Full Text Available Replication, cell tropism and the magnitude of the host's antiviral immune response each contribute to the resulting pathogenicity of influenza A viruses (IAV in humans. In contrast to seasonal IAV in human cases, the 2009 H1N1 pandemic IAV (H1N1pdm shows a greater tropism for infection of the lung similar to H5N1. We hypothesized that host responses during infection of well-differentiated, primary human bronchial epithelial cells (wd-NHBE may differ between seasonal (H1N1 A/BN/59/07 and H1N1pdm isolates from a fatal (A/KY/180/10 and nonfatal (A/KY/136/09 case. For each virus, the level of infectious virus and host response to infection (gene expression and apical/basal cytokine/chemokine profiles were measured in wd-NHBE at 8, 24, 36, 48 and 72 hours post-infection (hpi. At 24 and 36 hpi, KY/180 showed a significant, ten-fold higher titer as compared to the other two isolates. Apical cytokine/chemokine levels of IL-6, IL-8 and GRO were similar in wd-NHBE cells infected by each of these viruses. At 24 and 36 hpi, NHBE cells had greater levels of pro-inflammatory cytokines including IFN-α, CCL2, TNF-α, and CCL5, when infected by pandemic viruses as compared with seasonal. Polarization of IL-6 in wd-NHBE cells was greatest at 36 hpi for all isolates. Differential polarized secretion was suggested for CCL5 across isolates. Despite differences in viral titer across isolates, no significant differences were observed in KY/180 and KY/136 gene expression intensity profiles. Microarray profiles of wd-NHBE cells diverged at 36 hpi with 1647 genes commonly shared by wd-NHBE cells infected by pandemic, but not seasonal isolates. Significant differences were observed in cytokine signaling, apoptosis, and cytoskeletal arrangement pathways. Our studies revealed differences in temporal dynamics and basal levels of cytokine/chemokine responses of wd-NHBE cells infected with each isolate; however, wd-NHBE cell gene intensity profiles were not significantly

Influenza H5N1 virus infection of polarized human alveolar epithelial cells and lung microvascular endothelial cells

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Yuen Kit M

2009-10-01

Full Text Available Abstract Background Highly pathogenic avian influenza (HPAI H5N1 virus is entrenched in poultry in Asia and Africa and continues to infect humans zoonotically causing acute respiratory disease syndrome and death. There is evidence that the virus may sometimes spread beyond respiratory tract to cause disseminated infection. The primary target cell for HPAI H5N1 virus in human lung is the alveolar epithelial cell. Alveolar epithelium and its adjacent lung microvascular endothelium form host barriers to the initiation of infection and dissemination of influenza H5N1 infection in humans. These are polarized cells and the polarity of influenza virus entry and egress as well as the secretion of cytokines and chemokines from the virus infected cells are likely to be central to the pathogenesis of human H5N1 disease. Aim To study influenza A (H5N1 virus replication and host innate immune responses in polarized primary human alveolar epithelial cells and lung microvascular endothelial cells and its relevance to the pathogenesis of human H5N1 disease. Methods We use an in vitro model of polarized primary human alveolar epithelial cells and lung microvascular endothelial cells grown in transwell culture inserts to compare infection with influenza A subtype H1N1 and H5N1 viruses via the apical or basolateral surfaces. Results We demonstrate that both influenza H1N1 and H5N1 viruses efficiently infect alveolar epithelial cells from both apical and basolateral surface of the epithelium but release of newly formed virus is mainly from the apical side of the epithelium. In contrast, influenza H5N1 virus, but not H1N1 virus, efficiently infected polarized microvascular endothelial cells from both apical and basolateral aspects. This provides a mechanistic explanation for how H5N1 virus may infect the lung from systemic circulation. Epidemiological evidence has implicated ingestion of virus-contaminated foods as the source of infection in some instances and our

Diversity and environmental relations of cryptic, systemic Botrytis infections in symptomless hosts.

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Michael W. Shaw

2016-05-01

Full Text Available Botrytis species are generally considered to be aggressive, necrotrophic plant pathogens. By contrast to this general perception, however, Botrytis species could frequently be isolated from the interior of multiple tissues in apparently healthy hosts of many species. Infection frequencies reached 50% of samples or more, but were commonly less, and cryptic infections were rare or absent in some plant species. Prevalence varied substantially from year to year and from tissue to tissue, but some host species routinely had high prevalence. The same genotype was found to occur throughout a host, representing mycelial spread. B. cinerea and B. pseudocinerea are the species that most commonly occur as cryptic infections, but phylogenetically distant isolates of Botrytis were also detected, one of which does not correspond to previously described species. Sporulation and visible damage occurred only when infected tissues were stressed, or became mature or senescent. There was no evidence of cryptic infection having a deleterious effect on growth of the host, and prevalence was probably greater in plants grown in high light conditions. Isolates from cryptic infections were often capable of causing disease (to varying extents when spore suspensions were inoculated onto their own host as well as on distinct host species, arguing against co-adaptation between cryptic isolates and their hosts. These data collectively suggest that several Botrytis species, including the most notorious pathogenic species, exist frequently in cryptic form to an extent that has thus far largely been neglected, and do not need to cause disease on healthy hosts in order to complete their life-cycles.

Blood Groups in Infection and Host Susceptibility.

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Cooling, Laura

2015-07-01

Blood group antigens represent polymorphic traits inherited among individuals and populations. At present, there are 34 recognized human blood groups and hundreds of individual blood group antigens and alleles. Differences in blood group antigen expression can increase or decrease host susceptibility to many infections. Blood groups can play a direct role in infection by serving as receptors and/or coreceptors for microorganisms, parasites, and viruses. In addition, many blood group antigens facilitate intracellular uptake, signal transduction, or adhesion through the organization of membrane microdomains. Several blood groups can modify the innate immune response to infection. Several distinct phenotypes associated with increased host resistance to malaria are overrepresented in populations living in areas where malaria is endemic, as a result of evolutionary pressures. Microorganisms can also stimulate antibodies against blood group antigens, including ABO, T, and Kell. Finally, there is a symbiotic relationship between blood group expression and maturation of the gastrointestinal microbiome. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Blood Groups in Infection and Host Susceptibility

Science.gov (United States)

2015-01-01

SUMMARY Blood group antigens represent polymorphic traits inherited among individuals and populations. At present, there are 34 recognized human blood groups and hundreds of individual blood group antigens and alleles. Differences in blood group antigen expression can increase or decrease host susceptibility to many infections. Blood groups can play a direct role in infection by serving as receptors and/or coreceptors for microorganisms, parasites, and viruses. In addition, many blood group antigens facilitate intracellular uptake, signal transduction, or adhesion through the organization of membrane microdomains. Several blood groups can modify the innate immune response to infection. Several distinct phenotypes associated with increased host resistance to malaria are overrepresented in populations living in areas where malaria is endemic, as a result of evolutionary pressures. Microorganisms can also stimulate antibodies against blood group antigens, including ABO, T, and Kell. Finally, there is a symbiotic relationship between blood group expression and maturation of the gastrointestinal microbiome. PMID:26085552

The Pla Protease of Yersinia pestis Degrades Fas Ligand to Manipulate Host Cell Death and Inflammation

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Caulfield, Adam J.; Walker, Margaret E.; Gielda, Lindsay M.; Lathem, Wyndham W.

2014-01-01

SUMMARY Pneumonic plague is a deadly respiratory disease caused by Yersinia pestis. The bacterial protease Pla contributes to disease progression and manipulation of host immunity, but the mechanisms by which this occurs are largely unknown. Here we show that Pla degrades the apoptotic signaling molecule Fas ligand (FasL) to prevent host cell apoptosis and inflammation. Wild-type Y. pestis, but not a Pla mutant (Δpla), degrades FasL, which results in decreased downstream caspase-3/7 activation and reduced apoptosis. Similarly, lungs of mice challenged with wild-type Y. pestis show reduced levels of FasL and activated caspase-3/7 compared to Δpla infection. Consistent with a role for FasL in regulating immune responses, Δpla infection results in aberrant pro-inflammatory cytokine levels. The loss of FasL or inhibition of caspase activity alters host inflammatory responses and enables enhanced Y. pestis outgrowth in the lungs. Thus, by degrading FasL, Y. pestis manipulates host cell death pathways to facilitate infection. PMID:24721571

Temporal activation of anti- and pro-apoptotic factors in human gingival fibroblasts infected with the periodontal pathogen, Porphyromonas gingivalis: potential role of bacterial proteases in host signalling

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Takehara Tadamichi

2006-03-01

Full Text Available Abstract Background Porphyromonas gingivalis is the foremost oral pathogen of adult periodontitis in humans. However, the mechanisms of bacterial invasion and the resultant destruction of the gingival tissue remain largely undefined. Results We report host-P. gingivalis interactions in primary human gingival fibroblast (HGF cells. Quantitative immunostaining revealed the need for a high multiplicity of infection for optimal infection. Early in infection (2–12 h, P. gingivalis activated the proinflammatory transcription factor NF-kappa B, partly via the PI3 kinase/AKT pathway. This was accompanied by the induction of cellular anti-apoptotic genes, including Bfl-1, Boo, Bcl-XL, Bcl2, Mcl-1, Bcl-w and Survivin. Late in infection (24–36 h the anti-apoptotic genes largely shut down and the pro-apoptotic genes, including Nip3, Hrk, Bak, Bik, Bok, Bax, Bad, Bim and Moap-1, were activated. Apoptosis was characterized by nuclear DNA degradation and activation of caspases-3, -6, -7 and -9 via the intrinsic mitochondrial pathway. Use of inhibitors revealed an anti-apoptotic function of NF-kappa B and PI3 kinase in P. gingivalis-infected HGF cells. Use of a triple protease mutant P. gingivalis lacking three major gingipains (rgpA rgpB kgp suggested a role of some or all these proteases in myriad aspects of bacteria-gingival interaction. Conclusion The pathology of the gingival fibroblast in P. gingivalis infection is affected by a temporal shift from cellular survival response to apoptosis, regulated by a number of anti- and pro-apoptotic molecules. The gingipain group of proteases affects bacteria-host interactions and may directly promote apoptosis by intracellular proteolytic activation of caspase-3.

Predators and patterns of within-host growth can mediate both among-host competition and evolution of transmission potential of parasites.

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Auld, Stuart K J R; Hall, Spencer R; Housley Ochs, Jessica; Sebastian, Mathew; Duffy, Meghan A

2014-08-01

Parasite prevalence shows tremendous spatiotemporal variation. Theory indicates that this variation might stem from life-history characteristics of parasites and key ecological factors. Here, we illustrate how the interaction of an important predator and the schedule of transmission potential of two parasites can explain parasite abundance. A field survey showed that a noncastrating fungus (Metschnikowia bicuspidata) commonly infected a dominant zooplankton host (Daphnia dentifera), while a castrating bacterial parasite (Pasteuria ramosa) was rare. This result seemed surprising given that the bacterium produces many more infectious propagules (spores) than the fungus upon host death. The fungus's dominance can be explained by the schedule of within-host growth of parasites (i.e., how transmission potential changes over the course of infection) and the release of spores from "sloppy" predators (Chaoborus spp., who consume Daphnia prey whole and then later regurgitate the carapace and parasite spores). In essence, sloppy predators create a niche that the faster-schedule fungus currently occupies. However, a selection experiment showed that the slower-schedule bacterium can evolve into this faster-schedule, predator-mediated niche (but pays a cost in maximal spore yield to do so). Hence, our study shows how parasite life history can interact with predation to strongly influence the ecology, epidemiology, and evolution of infectious disease.

Follicular helper T cells promote liver pathology in mice during Schistosoma japonicum infection.

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Xiaojun Chen

2014-05-01

Full Text Available Following Schistosoma japonicum (S. japonicum infection, granulomatous responses are induced by parasite eggs trapped in host organs, particular in the liver, during the acute stage of disease. While excessive liver granulomatous responses can lead to more severe fibrosis and circulatory impairment in chronically infected host. However, the exact mechanism of hepatic granuloma formation has remained obscure. In this study, we for the first time showed that follicular helper T (Tfh cells are recruited to the liver to upregulate hepatic granuloma formation and liver injury in S. japonicum-infected mice, and identified a novel function of macrophages in Tfh cell induction. In addition, our results showed that the generation of Tfh cells driven by macrophages is dependent on cell-cell contact and the level of inducible costimulator ligand (ICOSL on macrophages which is regulated by CD40-CD40L signaling. Our findings uncovered a previously unappreciated role for Tfh cells in liver pathology caused by S. japonicum infection in mice.

Generational distribution of a Candida glabrata population: Resilient old cells prevail, while younger cells dominate in the vulnerable host.

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Bouklas, Tejas; Alonso-Crisóstomo, Luz; Székely, Tamás; Diago-Navarro, Elizabeth; Orner, Erika P; Smith, Kalie; Munshi, Mansa A; Del Poeta, Maurizio; Balázsi, Gábor; Fries, Bettina C

2017-05-01

Similar to other yeasts, the human pathogen Candida glabrata ages when it undergoes asymmetric, finite cell divisions, which determines its replicative lifespan. We sought to investigate if and how aging changes resilience of C. glabrata populations in the host environment. Our data demonstrate that old C. glabrata are more resistant to hydrogen peroxide and neutrophil killing, whereas young cells adhere better to epithelial cell layers. Consequently, virulence of old compared to younger C. glabrata cells is enhanced in the Galleria mellonella infection model. Electron microscopy images of old C. glabrata cells indicate a marked increase in cell wall thickness. Comparison of transcriptomes of old and young C. glabrata cells reveals differential regulation of ergosterol and Hog pathway associated genes as well as adhesion proteins, and suggests that aging is accompanied by remodeling of the fungal cell wall. Biochemical analysis supports this conclusion as older cells exhibit a qualitatively different lipid composition, leading to the observed increased emergence of fluconazole resistance when grown in the presence of fluconazole selection pressure. Older C. glabrata cells accumulate during murine and human infection, which is statistically unlikely without very strong selection. Therefore, we tested the hypothesis that neutrophils constitute the predominant selection pressure in vivo. When we altered experimentally the selection pressure by antibody-mediated removal of neutrophils, we observed a significantly younger pathogen population in mice. Mathematical modeling confirmed that differential selection of older cells is sufficient to cause the observed demographic shift in the fungal population. Hence our data support the concept that pathogenesis is affected by the generational age distribution of the infecting C. glabrata population in a host. We conclude that replicative aging constitutes an emerging trait, which is selected by the host and may even play an

Uptake and intra-inclusion accumulation of exogenous immunoglobulin by Chlamydia-infected cells

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Croteau Nancy L

2008-12-01

Full Text Available Abstract Background Obligate intracellular pathogens belonging to the Chlamydiaceae family possess a number of mechanisms by which to manipulate the host cell and surrounding environment. Such capabilities include the inhibition of apoptosis, down-regulation of major histocompatability complex (MHC and CD1/d gene expression, and the acquisition of host-synthesized nutrients. It is also documented that a limited number of host-derived macromolecules such as β-catenin and sphingomyelin accumulate within the inclusion. Results This report provides evidence that immunoglobulin, inherently present in the extracellular environment in vivo and in vitro, enters infected cells and accumulates within the chlamydial inclusion. Using epi-fluorescent and confocal microscopy, this selective uptake of Ig is shown to occur among human leukocytes in vivo as well as cells cultured in vitro. These findings were confirmed by detection of IgG in the lysate of infected cells by western blot hybridization. Sequestered antibodies appear to be present during the entire course of the chlamydial developmental cycle and are distributed throughout this compartment. IgG pre-labeled with fluorescein, when added to the supernatant of infected cell cultures, was also imported and readily visualized. Accumulation of these molecules within the inclusion and the failure of bovine serum albumin or F(ab'2 fragments to accumulate in a similar manner suggests the process of entry is specific for intact IgG molecules and not a result of pinocytosis, diffusion, or any other mass endocytic event. Conclusion Sequestration of a host cell-derived protein within the chlamydial inclusion, although unexpected, is not an unprecedented occurrence. However, selective accumulation of an exogenous host protein, such as extracellular IgG, has not been previously reported in connection with chlamydial infections. The selectivity of this process may indicate that this uptake plays an important role

Increased expression of the regulatory T cell-associated marker CTLA-4 in bovine leukemia virus infection.

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Suzuki, Saori; Konnai, Satoru; Okagawa, Tomohiro; Ikebuchi, Ryoyo; Nishimori, Asami; Kohara, Junko; Mingala, Claro N; Murata, Shiro; Ohashi, Kazuhiko

2015-02-15

Regulatory T cells (Tregs) play a critical role in the maintenance of the host's immune system. Tregs, particularly CD4(+)CD25(+)Foxp3(+) T cells, have been reported to be involved in the immune evasion mechanism of tumors and several pathogens that cause chronic infections. Recent studies showed that a Treg-associated marker, cytotoxic T-lymphocyte antigen 4 (CTLA-4), is closely associated with the progression of several diseases. We recently reported that the proportion of Foxp3(+)CD4(+) cells was positively correlated with the number of lymphocytes, virus titer, and virus load but inversely correlated with IFN-γ expression in cattle infected with bovine leukemia virus (BLV), which causes chronic infection and lymphoma in its host. Here the kinetics of CTLA-4(+) cells were analyzed in BLV-infected cattle. CTLA-4 mRNA was predominantly expressed in CD4(+) T cells in BLV-infected cattle, and the expression was positively correlated with Foxp3 mRNA expression. To test for differences in the protein expression level of CTLA-4, we measured the proportion of CTLA-4-expressing cells by flow cytometry. In cattle with persistent lymphocytosis (PL), mean fluorescence intensities (MFIs) of CTLA-4 on CD4(+) and CD25(+) T cells were significantly increased compared with that in control and aleukemic (AL) cattle. The percentage of CTLA-4(+) cells in the CD4(+) T cell subpopulation was positively correlated with TGF-β mRNA expression, suggesting that CD4(+)CTLA-4(+) T cells have a potentially immunosuppressive function in BLV infection. In the limited number of cattle that were tested, the anti-CTLA-4 antibody enhanced the expression of CD69, IL-2, and IFN-γ mRNA in anti-programmed death ligand 1 (PD-L1) antibody-treated peripheral blood mononuclear cells from BLV-infected cattle. Together with previous findings, the present results indicate that Tregs may be involved in the inhibition of T cell function during BLV infection. Copyright © 2014 Elsevier B.V. All rights

Alemtuzumab-induced elimination of HIV-1-infected immune cells.

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Ruxrungtham, Kiat; Sirivichayakul, Sunee; Buranapraditkun, Supranee; Krause, Werner

2016-01-01

Currently, there is no drug known that is able to eradicate either HIV or HIV-infected host cells. The effectiveness of all available treatments is based on the prevention of viral replication. We investigated whether the monoclonal, CD52 receptor-targeting antibody, alemtuzumab, which is currently approved for the treatment of multiple sclerosis, is able to eliminate HIV-infected immune cells. In blood samples from healthy donors and from HIV-1-infected subjects who were either treatment-naïve or resistant to HAART, we studied whether the CD52 expression on T cells and their subsets (CD3, CD4, CD8), B cells (CD19), dendritic cells (CD123) and monocytes (CD11c) is retained in HIV-1 infection and whether alemtuzumab is able to eradicate infected cells, using four-colour flow cytometry. We found that CD52 expression on immune cells is retained in HIV-1 infection regardless of CD4 cell count, viral load and treatment status, and is amenable to alemtuzumab-induced depletion. For the first time it could be shown in vitro that HIV-1-infected immune cells can be eliminated by using the monoclonal antibody alemtuzumab.

Bat lung epithelial cells show greater host species-specific innate resistance than MDCK cells to human and avian influenza viruses.

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Slater, Tessa; Eckerle, Isabella; Chang, Kin-Chow

2018-04-10

With the recent discovery of novel H17N10 and H18N11 influenza viral RNA in bats and report on high frequency of avian H9 seroconversion in a species of free ranging bats, an important issue to address is the extent bats are susceptible to conventional avian and human influenza A viruses. To this end, three bat species (Eidolon helvum, Carollia perspicillata and Tadarida brasiliensis) of lung epithelial cells were separately infected with two avian and two human influenza viruses to determine their relative host innate immune resistance to infection. All three species of bat cells were more resistant than positive control Madin-Darby canine kidney (MDCK) cells to all four influenza viruses. TB1-Lu cells lacked sialic acid α2,6-Gal receptors and were most resistant among the three bat species. Interestingly, avian viruses were relatively more replication permissive in all three bat species of cells than with the use of human viruses which suggest that bats could potentially play a role in the ecology of avian influenza viruses. Chemical inhibition of the JAK-STAT pathway in bat cells had no effect on virus production suggesting that type I interferon signalling is not a major factor in resisting influenza virus infection. Although all three species of bat cells are relatively more resistant to influenza virus infection than control MDCK cells, they are more permissive to avian than human viruses which suggest that bats could have a contributory role in the ecology of avian influenza viruses.

High content image based analysis identifies cell cycle inhibitors as regulators of Ebola virus infection.