Pfeiffer Dirk U
Full Text Available Abstract Background Currently, the highly pathogenic avian influenza virus (HPAIV of the subtype H5N1 is believed to have reached an endemic cycle in Vietnam. We used routine surveillance data on HPAIV H5N1 poultry outbreaks in Vietnam to estimate and compare the within-flock reproductive number of infection (R0 for periods before (second epidemic wave, 2004-5; depopulation-based disease control and during (fourth epidemic wave, beginning 2007; vaccination-based disease control vaccination. Results Our results show that infected premises (IPs in the initial (exponential phases of outbreak periods have the highest R0 estimates. The IPs reported during the outbreak period when depopulation-based disease control was implemented had higher R0 estimates than IPs reported during the outbreak period when vaccination-based disease control was used. In the latter period, in some flocks of a defined size and species composition, within-flock transmission estimates were not significantly below the threshold for transmission (R0 Conclusions Our results indicate that the current control policy based on depopulation plus vaccination has protected the majority of poultry flocks against infection. However, in some flocks the determinants associated with suboptimal protection need to be further investigated as these may explain the current pattern of infection in animal and human populations.
Tran Minh Quan
Full Text Available Arbovirus infections are a serious concern in tropical countries due to their high levels of transmission and morbidity. With the outbreaks of chikungunya (CHIKV in surrounding regions in recent years and the fact that the environment in Vietnam is suitable for the vectors of CHIKV, the possibility of transmission of CHIKV in Vietnam is of great interest. However, information about CHIKV activity in Vietnam remains limited.In order to address this question, we performed a systematic review of CHIKV in Vietnam and a CHIKV seroprevalence survey. The seroprevalence survey tested for CHIKV IgG in population serum samples from individuals of all ages in 2015 from four locations in Vietnam.The four locations were An Giang province (n = 137, Ho Chi Minh City (n = 136, Dak Lak province (n = 137, and Hue City (n = 136. The findings give us evidence of some CHIKV activity: 73/546 of overall samples were seropositive (13.4%. The age-adjusted seroprevalences were 12.30% (6.58-18.02, 13.42% (7.16-19.68, 7.97% (3.56-12.38, and 3.72% (1.75-5.69 in An Giang province, Ho Chi Minh City, Dak Lak province, and Hue City respectively. However, the age-stratified seroprevalence suggests that the last transmission ended around 30 years ago, consistent with results from the systematic review. We see no evidence for on-going transmission in three of the locations, though with some evidence of recent exposure in Dak Lak, most likely due to transmission in neighbouring countries. Before the 1980s, when transmission was occurring, we estimate on average 2-4% of the population were infected each year in HCMC and An Giang and Hue (though transmision ended earlier in Hue. We estimate lower transmission in Dak Lak, with around 1% of the population infected each year.In conclusion, we find evidence of past CHIKV transmission in central and southern Vietnam, but no evidence of recent sustained transmission. When transmission of CHIKV did occur, it appeared to be widespread and
Hoa, Le Nguyen Minh; Tuan, Nguyen Anh; My, Pham Ha; Huong, Tran Thi Kieu; Chi, Nguyen Thi Yen; Hau Thu, Trang Thi; Carrique-Mas, Juan; Duong, Mai Thuy; Tho, Nguyen Dang; Hoang, Nguyen Dang; Thanh, To Long; Diep, Nguyen Thi; Duong, Nguyen van; Toan, Tran Khanh; Tung, Trinh Son; Mai, Le Quynh; Iqbal, Munir; Wertheim, Heiman; van Doorn, H Rogier; Bryant, Juliet E; The Vizions Consortium
Rural farming communities in northern Vietnam do not routinely practice vaccination for influenza A viruses (IAV) for either humans or poultry, which enables us to study transmission intensity via seroepidemiology. Using samples from a longitudinal cohort of farming households, we determined the number of symptomatic and asymptomatic human infections for seasonal IAV and avian A/H9 over 2 years. As expected, we detected virologically confirmed acute cases of seasonal IAV in humans, as well as large numbers of subclinical seroconversions to A/H1pdm [55/265 (21 %)], A/H3 [95/265 (36 %)] and A/H9 [24/265 (9 %)]. Five of the A/H9 human seroconverters likely represented true infections rather than heterosubtypic immunity, because the individuals seroconverted solely to A/H9. Among co-located poultry, we found significantly higher seroprevalance for A/H5 compared to A/H9 in both chickens and ducks [for northern study sites overall, 337/1105 (30.5 %) seropositive for A/H5 and 123/1105 (11.1 %) seropositive for A/H9].
Full Text Available An unprecedented number of Ebola virus infections among healthcare workers and patients have raised questions about our understanding of Ebola virus transmission. Here, we explore different routes of Ebola virus transmission between people, summarizing the known epidemiological and experimental data. From this data, we expose important gaps in Ebola virus research pertinent to outbreak situations. We further propose experiments and methods of data collection that will enable scientists to fill these voids in our knowledge about the transmission of Ebola virus.
Otrashevskaia, E V; Kulak, M V; Otrashevskaia, A V; Karpov, I A; Fisenko, E G; Ignat'ev, G M
In this work we report the mumps vaccine virus shedding based on the laboratory confirmed cases of the mumps virus (MuV) infection. The likely epidemiological sources of the transmitted mumps virus were children who were recently vaccinated with the mumps vaccine containing Leningrad-Zagreb or Leningrad-3 MuV. The etiology of the described cases of the horizontal transmission of both mumps vaccine viruses was confirmed by PCR with the sequential restriction analysis.
Neumann, Gabriele; Kawaoka, Yoshihiro
Influenza A viruses cause respiratory infections that range from asymptomatic to deadly in humans. Widespread outbreaks (pandemics) are attributable to ‘novel’ viruses that possess a viral hemagglutinin (HA) gene to which humans lack immunity. After a pandemic, these novel viruses form stable virus lineages in humans and circulate until they are replaced by other novel viruses. The factors and mechanisms that facilitate virus transmission among hosts and the establishment of novel lineages are not completely understood, but the HA and basic polymerase 2 (PB2) proteins are thought to play essential roles in these processes by enabling avian influenza viruses to infect mammals and replicate efficiently in their new host. Here, we summarize our current knowledge of the contributions of HA, PB2, and other viral components to virus transmission and the formation of new virus lineages. PMID:25812763
Takemae, N; Nguyen, P T; Le, V T; Nguyen, T N; To, T L; Nguyen, T D; Pham, V P; Vo, H V; Le, Q V T; Do, H T; Nguyen, D T; Uchida, Y; Saito, T
Three subtypes-H1N1, H1N2 and H3N2-of influenza A viruses of swine (IAVs-S) are currently endemic in swine worldwide, but there is considerable genotypic diversity among each subtype and limited geographical distribution. Through IAVs-S monitoring in Vietnam, two H1N2 influenza A viruses were isolated from healthy pigs in Ba Ria-Vung Tau Province, Southern Vietnam, on 2 December 2016. BLAST and phylogenetic analyses revealed that their HA and NA genes were derived from those of European avian-like H1N2 IAVs-S that contained avian-origin H1 and human-like N2 genes, and were particularly closely related to those of IAVs-S circulating in the Netherlands, Germany or Denmark. In addition, the internal genes of these Vietnamese isolates were derived from human A(H1N1)pdm09 viruses, suggesting that the Vietnamese H1N2 IAVs-S are reassortants between European H1N2 IAVs-S and human A(H1N1)pdm09v. The appearance of European avian-like H1N2 IAVs-S in Vietnam marks their first transmission outside Europe. Our results and statistical analyses of the number of live pigs imported into Vietnam suggest that the European avian-like H1N2 IAVs-S may have been introduced into Vietnam with their hosts through international trade. These findings highlight the importance of quarantining imported pigs to impede the introduction of new IAVs-S. © 2018 Blackwell Verlag GmbH.
Frédéric M. Hamelin; Linda J.S. Allen; Holly R. Prendeville; M. Reza Hajimorad; Michael J. Jeger
The evolution of plant virus transmission pathways is studied through transmission via seed, pollen, oravector. We address the questions: under what circumstances does vector transmission make pollen transmission redundant? Can evolution lead to the coexistence of multiple virus transmission pathways? We restrict the analysis to an annual plant population in which...
Campbell, R N
Thirty soilborne viruses or virus-like agents are transmitted by five species of fungal vectors. Ten polyhedral viruses, of which nine are in the family Tombusviridae, are acquired in the in vitro manner and do not occur within the resting spores of their vectors, Olpidium brassicae and O. bornovanus. Fungal vectors for other viruses in the family should be sought even though tombusviruses are reputed to be soil transmitted without a vector. Eighteen rod-shaped viruses belonging to the furo- and bymovirus groups and to an unclassified group are acquired in the in vivo manner and survive within the resting spores of their vector, O. brassicae, Polymyxa graminis, P. betae, and Spongospora subterranea. The viral coat protein has an essential role in in vitro transmission. With in vivo transmission a site in the coat protein-read through protein (CP-RT) of beet necrotic yellow vein furovirus determines vector transmissibility as does a site in a similar 98-kDa polyprotein of barley mild mosaic bymovirus. The mechanisms by which virions move (or are moved) into and out of the protoplasm of zoospores or of thalli needs study.
Sharmi W Thor
Full Text Available Highly pathogenic avian influenza (HPAI H5N1 is endemic in Vietnamese poultry and has caused sporadic human infection in Vietnam since 2003. Human infections with HPAI H5N1 are of concern due to a high mortality rate and the potential for the emergence of pandemic viruses with sustained human-to-human transmission. Viruses isolated from humans in southern Vietnam have been classified as clade 1 with a single genome constellation (VN3 since their earliest detection in 2003. This is consistent with detection of this clade/genotype in poultry viruses endemic to the Mekong River Delta and surrounding regions. Comparison of H5N1 viruses detected in humans from southern Vietnamese provinces during 2012 and 2013 revealed the emergence of a 2013 reassortant virus with clade 1.1.2 hemagglutinin (HA and neuraminidase (NA surface protein genes but internal genes derived from clade 220.127.116.11a viruses (A/Hubei/1/2010-like; VN12. Closer analysis revealed mutations in multiple genes of this novel genotype (referred to as VN49 previously associated with increased virulence in animal models and other markers of adaptation to mammalian hosts. Despite the changes identified between the 2012 and 2013 genotypes analyzed, their virulence in a ferret model was similar. Antigenically, the 2013 viruses were less cross-reactive with ferret antiserum produced to the clade 1 progenitor virus, A/Vietnam/1203/2004, but reacted with antiserum produced against a new clade 1.1.2 WHO candidate vaccine virus (A/Cambodia/W0526301/2012 with comparable hemagglutination inhibition titers as the homologous antigen. Together, these results indicate changes to both surface and internal protein genes of H5N1 viruses circulating in southern Vietnam compared to 2012 and earlier viruses.
Nguyen, Dung Van; Suzuki, Junko; Minami, Shohei; Yonemitsu, Kenzo; Nagata, Nao; Kuwata, Ryusei; Shimoda, Hiroshi; Vu, Chien Kim; Truong, Thuy Quoc; Maeda, Ken
Canine distemper virus (CDV) is one of the most serious pathogens found in many species of carnivores, including domestic dogs. In this study, hemagglutinin (H) genes were detected in five domestic Vietnamese dogs with diarrhea, and two CDVs were successfully isolated from dogs positive for H genes. The complete genome of one isolate, CDV/dog/HCM/33/140816, was determined. Phylogenetic analysis showed that all Vietnamese CDVs belonged to the Asia-1 genotype. In addition, the H proteins of Vietnamese CDV strains were the most homologous to those of Chinese CDVs (98.4% to 99.3% identity). These results indicated that the Asia-1 genotype of CDV was the predominant genotype circulating among the domestic dog population in Vietnam and that transboundary transmission of CDV has occurred between Vietnam and China.
Emmie de Wit
Full Text Available Based on epidemiological data, it is believed that human-to-human transmission plays an important role in Nipah virus outbreaks. No experimental data are currently available on the potential routes of human-to-human transmission of Nipah virus. In a first dose-finding experiment in Syrian hamsters, it was shown that Nipah virus was predominantly shed via the respiratory tract within nasal and oropharyngeal secretions. Although Nipah viral RNA was detected in urogenital and rectal swabs, no infectious virus was recovered from these samples, suggesting no viable virus was shed via these routes. In addition, hamsters inoculated with high doses shed significantly higher amounts of viable Nipah virus particles in comparison with hamsters infected with lower inoculum doses. Using the highest inoculum dose, three potential routes of Nipah virus transmission were investigated in the hamster model: transmission via fomites, transmission via direct contact and transmission via aerosols. It was demonstrated that Nipah virus is transmitted efficiently via direct contact and inefficiently via fomites, but not via aerosols. These findings are in line with epidemiological data which suggest that direct contact with nasal and oropharyngeal secretions of Nipah virus infected individuals resulted in greater risk of Nipah virus infection. The data provide new and much-needed insights into the modes and efficiency of Nipah virus transmission and have important public health implications with regards to the risk assessment and management of future Nipah virus outbreaks.
Ta, Hoang-Anh; Nguyen, Doan-Phuong; Causse, Sandrine; Nguyen, Thanh-Duc; Ngo, Vinh-Vien; Hébrard, Eugénie
Rice grassy stunt virus (RGSV, Tenuivirus) recently emerged on rice in Vietnam, causing high yield losses during 2006-2009. The genetic diversity of RGSV is poorly documented. In this study, the two genes encoded by each ambisense segment RNA3 and RNA5 of RGSV isolates from six provinces of South Vietnam were sequenced. P3 and Pc3 (RNA3) have unknown function, P5 (RNA5) encodes the putative silencing suppressor, and Pc5 (RNA5) encodes the nucleocapsid protein (N). The sequences of 17 Vietnamese isolates were compared with reference isolates from North and South Philippines. The average nucleotide diversity among the isolates was low. We confirmed a higher variability of RNA3 than RNA5 and Pc3 than P3. No relationships between the genetic diversity and the geographic distribution of RGSV isolates could be ascertained, likely because of the long-distance migration of the insect vector. This data will contribute to a better understanding on the RGSV epidemiology in South Vietnam, a prerequisite for further management of the disease and rice breeding for resistance.
Sosna William A
Full Text Available Abstract Background There is limited knowledge about the potential routes for H5N1 influenza virus transmission to and between humans, and it is not clear whether humans can be infected through inhalation of aerosolized H5N1 virus particles. Ferrets are often used as a animal model for humans in influenza pathogenicity and transmissibility studies. In this manuscript, a nose-only bioaerosol inhalation exposure system that was recently developed and validated was used in an inhalation exposure study of aerosolized A/Vietnam/1203/2004 (H5N1 virus in ferrets. The clinical spectrum of influenza resulting from exposure to A/Vietnam/1203/2004 (H5N1 through intranasal verses inhalation routes was analyzed. Results Ferrets were successfully infected through intranasal instillation or through inhalation of small particle aerosols with four different doses of Influenza virus A/Vietnam/1203/2004 (H5N1. The animals developed severe influenza encephalomyelitis following intranasal or inhalation exposure to 101, 102, 103, or 104 infectious virus particles per ferret. Conclusions Aerosolized Influenza virus A/Vietnam/1203/2004 (H5N1 is highly infectious and lethal in ferrets. Clinical signs appeared earlier in animals infected through inhalation of aerosolized virus compared to those infected through intranasal instillation.
Le, Mai Quynh; Lam, Ha Minh; Cuong, Vuong Duc; Lam, Tommy Tsan-Yuk; Halpin, Rebecca A; Wentworth, David E; Hien, Nguyen Tran; Thanh, Le Thi; Phuong, Hoang Vu Mai; Horby, Peter; Boni, Maciej F
Understanding global influenza migration and persistence is crucial for vaccine strain selection. Using 240 new human influenza A virus whole genomes collected in Vietnam during 2001-2008, we looked for persistence patterns and migratory connections between Vietnam and other countries. We found that viruses in Vietnam migrate to and from China, Hong Kong, Taiwan, Cambodia, Japan, South Korea, and the United States. We attempted to reduce geographic bias by generating phylogenies subsampled at the year and country levels. However, migration events in these phylogenies were still driven by the presence or absence of sequence data, indicating that an epidemiologic study design that controls for prevalence is required for robust migration analysis. With whole-genome data, most migration events are not detectable from the phylogeny of the hemagglutinin segment alone, although general migratory relationships between Vietnam and other countries are visible in the hemagglutinin phylogeny. It is possible that virus lineages in Vietnam persisted for >1 year.
Le, Mai Quynh; Lam, Ha Minh; Cuong, Vuong Duc; Lam, Tommy Tsan-Yuk; Halpin, Rebecca A; Wentworth, David E; Hien, Nguyen Tran; Thanh, Le Thi; Phuong, Hoang Vu Mai; Horby, Peter
Understanding global influenza migration and persistence is crucial for vaccine strain selection. Using 240 new human influenza A virus whole genomes collected in Vietnam during 2001–2008, we looked for persistence patterns and migratory connections between Vietnam and other countries. We found that viruses in Vietnam migrate to and from China, Hong Kong, Taiwan, Cambodia, Japan, South Korea, and the United States. We attempted to reduce geographic bias by generating phylogenies subsampled at the year and country levels. However, migration events in these phylogenies were still driven by the presence or absence of sequence data, indicating that an epidemiologic study design that controls for prevalence is required for robust migration analysis. With whole-genome data, most migration events are not detectable from the phylogeny of the hemagglutinin segment alone, although general migratory relationships between Vietnam and other countries are visible in the hemagglutinin phylogeny. It is possible that virus lineages in Vietnam persisted for >1 year. PMID:24188643
Herfst, S; Imai, M; Kawaoka, Y; Fouchier, R A M
Influenza A viruses cause yearly epidemics and occasional pandemics. In addition, zoonotic influenza A viruses sporadically infect humans and may cause severe respiratory disease and fatalities. Fortunately, most of these viruses do not have the ability to be efficiently spread among humans via aerosols or respiratory droplets (airborne transmission) and to subsequently cause a pandemic. However, adaptation of these zoonotic viruses to humans by mutation or reassortment with human influenza A viruses may result in airborne transmissible viruses with pandemic potential. Although our knowledge of factors that affect mammalian adaptation and transmissibility of influenza viruses is still limited, we are beginning to understand some of the biological traits that drive airborne transmission of influenza viruses among mammals. Increased understanding of the determinants and mechanisms of airborne transmission may aid in assessing the risks posed by avian influenza viruses to human health, and preparedness for such risks. This chapter summarizes recent discoveries on the genetic and phenotypic traits required for avian influenza viruses to become airborne transmissible between mammals.
First page Back Continue Last page Overview Graphics. Virus isolation: Specimen type and probable transmission. Over 500 CHIK virus isolations were made. 4 from male Ae. Aegypti (?TOT). 6 from CSF (neurological involvement). 1 from a 4-day old child (transplacental transmission.
Pham, Duc Anh; Leuangwutiwong, Pornsawan; Jittmittraphap, Akanitt; Luplertlop, Nattanej; Bach, Hoa Khanh; Akkarathamrongsin, Srunthron; Theamboonlers, Apiradee; Poovorawan, Yong
This study aimed to update the prevalence of the various Hepatitis C virus genotypes in Vietnamese blood donors. One hundred and three HCV antibody-positive plasma samples were collected from blood donors at the National Institute of Hematology and Blood Transfusion, Hanoi, Vietnam. All specimens were subjected to RT-PCR of the 5' untranslated region (UTR) to confirm the presence of HCV RNA. The core and NS5B regions of thh positive samples were subsequently amplified by RT-PCR followed by direct sequencing and phylogenetic analysis. Seventy out of 103 samples (68.0%) were RNA positive. Core and NS5B were successfully amplified and sequences were obtained for 70 and 65 samples, respectively. Phylogenetic analysis revealed that genotype 6a was the most predominant among Vietnamese blood donors with a prevalence of 37.1% (26/70), followed by genotype 1a at 30.0% (21/70) and genotype 1b at 17.1% (12/70). The prevalence of two other genotype 6 variants, 6e and 61 was 8.6% and 1.4%, respectively. Further analysis of recent studies showed that the geographic distribution of genotype 6 covered mainly southern China and the mainland of Southeast Asia including Vietnam, Laos, Thailand, and Myanmar. The GenBank accession numbers for the sequences reported in this study are FJ768772-FJ768906.
This document presents the energy profile of Vietnam: energy organizations and policy; companies: Petrovietnam (oil), Vietgas (gas), Power Company 1, 2 and 3 (PC1, PC2, PC3) and Electricite du Vietnam (electric power), Vinacoal (coal); supplies (resources, electric power, oil, gas and coal); prices; consumption; projects and perspectives. (J.S.)
taken with the eager collaboration of Vietnam's government, have since ... social sciences; and environment and natural resource management) was ... deliberate and increasing openness to the world of trade, investment, and knowl- edge ... Vietnam design trade liberalization and competition policies (in part as preparation.
Full Text Available Highly pathogenic avian influenza (HPAI H5N1 viruses have caused dramatic economic losses to the poultry industry of Vietnam and continue to pose a serious threat to public health. As of June 2008, Vietnam had reported nearly one third of worldwide laboratory confirmed human H5N1 infections. To better understand the emergence, spread and evolution of H5N1 in Vietnam we studied over 300 H5N1 avian influenza viruses isolated from Vietnam since their first detection in 2001. Our phylogenetic analyses indicated that six genetically distinct H5N1 viruses were introduced into Vietnam during the past seven years. The H5N1 lineage that evolved following the introduction in 2003 of the A/duck/Hong Kong/821/2002-like viruses, with clade 1 hemagglutinin (HA, continued to predominate in southern Vietnam as of May 2007. A virus with a clade 2.3.4 HA newly introduced into northern Vietnam in 2007, reassorted with pre-existing clade 1 viruses, resulting in the emergence of novel genotypes with neuraminidase (NA and/or internal gene segments from clade 1 viruses. A total of nine distinct genotypes have been present in Vietnam since 2001, including five that were circulating in 2007. At least four of these genotypes appear to have originated in Vietnam and represent novel H5N1 viruses not reported elsewhere. Geographic and temporal analyses of H5N1 infection dynamics in poultry suggest that the majority of viruses containing new genes were first detected in northern Vietnam and subsequently spread to southern Vietnam after reassorting with pre-existing local viruses in northern Vietnam. Although the routes of entry and spread of H5N1 in Vietnam remain speculative, enhanced poultry import controls and virologic surveillance efforts may help curb the entry and spread of new HPAI viral genes.
Chu, Dinh-Toi; Ngoc, Vo Truong Nhu; Tao, Yang
Zika virus infection and its associated microcephaly have being receiving global concern. This infection has spread widely since the first outbreak was recorded in Africa in 1952. Now, it has been reported in over 70 countries on five continents including Africa, North and South America, Asia, and Europe. Vietnam is one of the most recent countries which had cases of Zika virus infection at the end of 2016. This country has also reported the first case of a microcephaly-born baby which was probably linked to Zika virus infection. However, information on the Zika virus epidemic in Vietnam is still limited. This brief report intends to update the current Zika virus epidemic, and to discuss challenges and perspectives in controlling this infection in Vietnam.
Yen, Hui-Ling; Lipatov, Aleksandr S; Ilyushina, Natalia A; Govorkova, Elena A; Franks, John; Yilmaz, Neziha; Douglas, Alan; Hay, Alan; Krauss, Scott; Rehg, Jerold E; Hoffmann, Erich; Webster, Robert G
The abilities to infect and transmit efficiently among humans are essential for a novel influenza A virus to cause a pandemic. To evaluate the pandemic potential of widely disseminated H5N1 influenza viruses, a ferret contact model using experimental groups comprised of one inoculated ferret and two contact ferrets was used to study the transmissibility of four human H5N1 viruses isolated from 2003 to 2006. The effects of viral pathogenicity and receptor binding specificity (affinity to synthetic sialosaccharides with alpha2,3 or alpha2,6 linkages) on transmissibility were assessed. A/Vietnam/1203/04 and A/Vietnam/JP36-2/05 viruses, which possess "avian-like" alpha2,3-linked sialic acid (SA) receptor specificity, caused neurological symptoms and death in ferrets inoculated with 10(3) 50% tissue culture infectious doses. A/Hong Kong/213/03 and A/Turkey/65-596/06 viruses, which show binding affinity for "human-like" alpha2,6-linked SA receptors in addition to their affinity for alpha2,3-linked SA receptors, caused mild clinical symptoms and were not lethal to the ferrets. No transmission of A/Vietnam/1203/04 or A/Turkey/65-596/06 virus was detected. One contact ferret developed neutralizing antibodies to A/Hong Kong/213/03 but did not exhibit any clinical signs or detectable virus shedding. In two groups, one of two naïve contact ferrets had detectable virus after 6 to 8 days when housed together with the A/Vietnam/JP36-2/05 virus-inoculated ferrets. Infected contact ferrets showed severe clinical signs, although little or no virus was detected in nasal washes. This limited virus shedding explained the absence of secondary transmission from the infected contact ferret to the other naïve ferret that were housed together. Our results suggest that despite their receptor binding affinity, circulating H5N1 viruses retain molecular determinants that restrict their spread among mammalian species.
This document summarizes the main energy facts and data about Vietnam: institutions and energy policy, energy companies (Petrovietnam (oil), Vietgas (gas), Electricity of Vietnam (EVN), Vinacoal (coal)), energy production (resources, electricity, oil, natural gas, coal), energy prices (motor fuels and electricity), energy consumption, and future energy issues and prospects (exploitation of new fossil fuel resources, building of new refineries and power stations). The main economic, supply and demand, and energy balance indicators are summarized in tables and graphics. (J.S.)
Attention in this discussion of Vietnam is directed to the following: people; geography; history; government; the economy (agriculture and industry, trade and balance of payments); foreign relations; and relations between the US and Vietnam. In mid-1983 the population was estimated at 57,610,000 with an annual growth rate of 2.4%. Ethnic Vietnamese constitute almost 90% of the population. Various ethnic groups make up the remaining 10% of the population, with approximately 1.2 million Chinese being the most numerous and concentrated in southern Vietnam. The 2nd largest minority, the Montagnards (mountain tribesmen) comprise 2 main ethnolinguistic groups--Malayo Polynesia and Mon-Khmer. The most important political institution in Vietnam is the Vietnamese Communisty Party. All but 4 party Politburo members concurrently hold high positions in the government. The most important powers within the Vietnamese government, as opposed to the Communisty Party, are the executive agencies. Under the overly ambitious initial 5 year plan and the more conservative 1981-85 plan, the Vietnamese have made little progress in raising output and living standards beyond the levels of the 1960s. Guidelines of the 1981-85 plan call for attaining food self sufficiency, strengthening export and consumer industries, as well as the heavy industries that support them, and improving transport and energy production. The US does not have diplomatic relations with Vietnam.
Nguyen, Doan C.; Uyeki, Timothy M.; Jadhao, Samadhan; Maines, Taronna; Shaw, Michael; Matsuoka, Yumiko; Smith, Catherine; Rowe, Thomas; Lu, Xiuhua; Hall, Henrietta; Xu, Xiyan; Balish, Amanda; Klimov, Alexander; Tumpey, Terrence M.; Swayne, David E.; Huynh, Lien P. T.; Nghiem, Ha K.; Nguyen, Hanh H. T.; Hoang, Long T.; Cox, Nancy J.; Katz, Jacqueline M.
Since 1997, outbreaks of highly pathogenic (HP) H5N1 and circulation of H9N2 viruses among domestic poultry in Asia have posed a threat to public health. To better understand the extent of transmission of avian influenza viruses (AIV) to humans in Asia, we conducted a cross-sectional virologic study in live bird markets (LBM) in Hanoi, Vietnam, in October 2001. Specimens from 189 birds and 18 environmental samples were collected at 10 LBM. Four influenza A viruses of the H4N6 (n = 1), H5N2 (n = 1), and H9N3 (n = 2) subtypes were isolated from healthy ducks for an isolation frequency of over 30% from this species. Two H5N1 viruses were isolated from healthy geese. The hemagglutinin (HA) genes of these H5N1 viruses possessed multiple basic amino acid motifs at the cleavage site, were HP for experimentally infected chickens, and were thus characterized as HP AIV. These HA genes shared high amino acid identities with genes of other H5N1 viruses isolated in Asia during this period, but they were genetically distinct from those of H5N1 viruses isolated from poultry and humans in Vietnam during the early 2004 outbreaks. These viruses were not highly virulent for experimentally infected ducks, mice, or ferrets. These results establish that HP H5N1 viruses with properties similar to viruses isolated in Hong Kong and mainland China circulated in Vietnam as early as 2001, suggest a common source for H5N1 viruses circulating in these Asian countries, and provide a framework to better understand the recent widespread emergence of HP H5N1 viruses in Asia. PMID:15767421
The Dong Phung
Full Text Available In order to conduct an effective monetary policy, the Central bank should have a clear understanding of the mechanism of the money transfer and the importance of different transmission channels, and the impact of these transmission channels on the sectors of the economy, especially on the manufacturing sector.
Carrel, Margaret A.; Emch, Michael; Jobe, R. Todd; Moody, Aaron; Wan, Xiu-Feng
Background Vietnam is one of the countries most affected by outbreaks of H5N1 highly pathogenic avian influenza viruses. First identified in Vietnam in poultry in 2001 and in humans in 2004, the virus has since caused 111 cases and 56 deaths in humans. In 2003/2004 H5N1 outbreaks, nearly the entire poultry population of Vietnam was culled. Our earlier study (Wan et al., 2008, PLoS ONE, 3(10): e3462) demonstrated that there have been at least six independent H5N1 introductions into Vietnam and...
This podcast discusses a study about the probable unusual transmission of Zika Virus Infection from a scientist to his wife, published in the May 2011 issue of Emerging Infectious Diseases. Dr. Brian Foy, Associate Professor at Colorado State University, shares details of this event.
Kristensen, C.S.; Bøtner, Anette; Takai, H.
A series of three experiments, differing primarily in airflow volume, were performed to evaluate the likelihood of airborne transmission of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) from infected to non-infected pigs. Pigs were housed in two units (unit A and unit B) located 1 m...
Monica Dwi Hartanti
Full Text Available Dengue is a disease that is caused by dengue virus and transmitted to humans through the bite of infected Aedes mosquitoes, especially Aedes aegypti. The disease is hyper-endemic in Southeast Asia, where a more severe form, dengue hemorrhagic fever (DHF and dengue shock syndrome (DSS, is a major public health concern. The purpose of the present study was to find evidence of dengue virus transovarial transmision in local vectors in Jakarta. Fifteen Aedes larvae were collected in 2009 from two areas in Tebet subdistrict in South Jakarta, namely one area with the highest and one with the lowest DHF prevalence. All mosquitoes were reared inside two cages in the laboratory, eight mosquitoes in one cage and seven mosquitoes in another cage and given only sucrose solution as their food. The results showed that 20% of the mosquitoes were positive for dengue virus. Dengue virus detection with an immunohistochemical method demonstrated the occurrence of transovarial transmission in local DHF vectors in Tebet subdistrict. Transovarial dengue infection in Ae.aegypti larvae appeared to maintain or enhance epidemics. Further research is needed to investigate the relation of dengue virus transovarial transmission with DHF endemicity in Jakarta.
Monica Dwi Hartanti
Full Text Available Dengue is a disease that is caused by dengue virus and transmitted to humans through the bite of infected Aedes mosquitoes, especially Aedes aegypti. The disease is hyper-endemic in Southeast Asia, where a more severe form, dengue hemorrhagic fever (DHF and dengue shock syndrome (DSS, is a major public health concern. The purpose of the present study was to find evidence of dengue virus transovarial transmision in local vectors in Jakarta. Fifteen Aedes larvae were collected in 2009 from two areas in Tebet subdistrict in South Jakarta, namely one area with the highest and one with the lowest DHF prevalence. All mosquitoes were reared inside two cages in the laboratory, eight mosquitoes in one cage and seven mosquitoes in another cage and given only sucrose solution as their food. The results showed that 20% of the mosquitoes were positive for dengue virus. Dengue virus detection with an immunohistochemical method demonstrated the occurrence of transovarial transmission in local DHF vectors in Tebet subdistrict. Transovarial dengue infection in Ae.aegypti larvae appeared to maintain or enhance epidemics. Further research is needed to investigate the relation of dengue virus transovarial transmission with DHF endemicity in Jakarta.
This podcast discusses a study about the probable unusual transmission of Zika Virus Infection from a scientist to his wife, published in the May 2011 issue of Emerging Infectious Diseases. Dr. Brian Foy, Associate Professor at Colorado State University, shares details of this event. Created: 5/23/2011 by National Center for Emerging Zoonotic and Infectious Diseases (NCEZID). Date Released: 5/25/2011.
Dung, Bui Thi; Doanh, Pham Ngoc; The, Dang Tat; Loan, Ho Thi; Losson, Bertrand; Caron, Yannick
Freshwater snails of the family Lymnaeidae play an important role in the transmission of fascioliasis worldwide. In Vietnam, 2 common lymnaeid species, Lymnaea swinhoei and Lymnaea viridis, can be recognized on the basis of morphology, and a third species, Lymnaea sp., is known to exist. Recent studies have raised controversy about their role in transmission of Fasciola spp. because of confusion in identification of the snail hosts. The aim of this study is, therefore, to clarify the identities of lymnaeid snails in Vietnam by a combination of morphological and molecular approaches. The molecular analyses using the second internal transcribed spacer (ITS2) of the nuclear ribosomal DNA clearly showed that lymnaeids in Vietnam include 3 species, Austropeplea viridis (morphologically identified as L. viridis), Radix auricularia (morphologically identified as L. swinhoei) and Radix rubiginosa (morphologically identified as Lymnaea sp.). R. rubiginosa is a new record for Vietnam. Among them, only A. viridis was found to be infected with Fasciola spp. These results provide a new insight into lymnaeid snails in Vietnam. Identification of lymnaeid snails in Vietnam and their role in the liver fluke transmission should be further investigated.
Le, Mai T. Q.; Wertheim, Heiman F. L.; Nguyen, Hien D.; Taylor, Walter; Hoang, Phuong V. M.; Vuong, Cuong D.; Nguyen, Hang L. K.; Nguyen, Ha H.; Nguyen, Thai Q.; Nguyen, Trung V.; van, Trang D.; Ngoc, Bich T.; Bui, Thinh N.; Nguyen, Binh G.; Nguyen, Liem T.; Luong, San T.; Phan, Phuc H.; Pham, Hung V.; Nguyen, Tung; Fox, Annette; Nguyen, Cam V.; Do, Ha Q.; Crusat, Martin; Farrar, Jeremy; Nguyen, Hien T.; de Jong, Menno D.; Horby, Peter
BACKGROUND: Prior to 2007, highly pathogenic avian influenza (HPAI) H5N1 viruses isolated from poultry and humans in Vietnam were consistently reported to be clade 1 viruses, susceptible to oseltamivir but resistant to amantadine. Here we describe the re-emergence of human HPAI H5N1 virus infections
Do Manh Cuong
Full Text Available Abstract Background Malaria is still prevalent in rural communities of central Vietnam even though, due to deforestation, the primary vector Anopheles dirus is uncommon. In these situations little is known about the secondary vectors which are responsible for maintaining transmission. Basic information on the identification of the species in these rural communities is required so that transmission parameters, such as ecology, behaviour and vectorial status can be assigned to the appropriate species. Methods In two rural villages - Khe Ngang and Hang Chuon - in Truong Xuan Commune, Quang Binh Province, north central Vietnam, a series of longitudinal entomological surveys were conducted during the wet and dry seasons from 2003 - 2007. In these surveys anopheline mosquitoes were collected in human landing catches, paired human and animal bait collections, and from larval surveys. Specimens belonging to species complexes were identified by PCR and sequence analysis, incrimination of vectors was by detection of circumsporozoite protein using an enzyme-linked immunosorbent assay. Results Over 80% of the anopheline fauna was made up of Anopheles sinensis, Anopheles aconitus, Anopheles harrisoni, Anopheles maculatus, Anopheles sawadwongporni, and Anopheles philippinensis. PCR and sequence analysis resolved identification issues in the Funestus Group, Maculatus Group, Hyrcanus Group and Dirus Complex. Most species were zoophilic and while all species could be collected biting humans significantly higher densities were attracted to cattle and buffalo. Anopheles dirus was the most anthropophilic species but was uncommon making up only 1.24% of all anophelines collected. Anopheles sinensis, An. aconitus, An. harrisoni, An. maculatus, An. sawadwongporni, Anopheles peditaeniatus and An. philippinensis were all found positive for circumsporozoite protein. Heterogeneity in oviposition site preference between species enabled vector densities to be high in both
Carrel, Margaret A; Emch, Michael; Jobe, R Todd; Moody, Aaron; Wan, Xiu-Feng
Vietnam is one of the countries most affected by outbreaks of H5N1 highly pathogenic avian influenza viruses. First identified in Vietnam in poultry in 2001 and in humans in 2004, the virus has since caused 111 cases and 56 deaths in humans. In 2003/2004 H5N1 outbreaks, nearly the entire poultry population of Vietnam was culled. Our earlier study (Wan et al., 2008, PLoS ONE, 3(10): e3462) demonstrated that there have been at least six independent H5N1 introductions into Vietnam and there were nine newly emerged reassortants from 2001 to 2007 in Vietnam. H5N1 viruses in Vietnam cluster distinctly around Hanoi and Ho Chi Minh City. However, the nature of the relationship between genetic divergence and geographic patterns is still unclear. In this study, we hypothesized that genetic distances between H5N1 viruses in Vietnam are correlated with geographic distances, as the result of distinct population and environment patterns along Vietnam's long north to south longitudinal extent. Based on this hypothesis, we combined spatial statistical methods with genetic analytic techniques and explicitly used geographic space to explore genetic evolution of H5N1 highly pathogenic avian influenza viruses at the sub-national scale in Vietnam. Our dataset consisted of 125 influenza viruses (with whole genome sets) isolated in Vietnam from 2003 to 2007. Our results document the significant effect of space and time on genetic evolution and the rise of two regional centers of genetic mixing by 2007. These findings give insight into processes underlying viral evolution and suggest that genetic differentiation is associated with the distance between concentrations of human and poultry populations around Hanoi and Ho Chi Minh City. The results show that genetic evolution of H5N1 viruses in Vietnamese domestic poultry is highly correlated with the location and spread of those viruses in geographic space. This correlation varies by scale, time, and gene, though a classic isolation by
Margaret A Carrel
Full Text Available Vietnam is one of the countries most affected by outbreaks of H5N1 highly pathogenic avian influenza viruses. First identified in Vietnam in poultry in 2001 and in humans in 2004, the virus has since caused 111 cases and 56 deaths in humans. In 2003/2004 H5N1 outbreaks, nearly the entire poultry population of Vietnam was culled. Our earlier study (Wan et al., 2008, PLoS ONE, 3(10: e3462 demonstrated that there have been at least six independent H5N1 introductions into Vietnam and there were nine newly emerged reassortants from 2001 to 2007 in Vietnam. H5N1 viruses in Vietnam cluster distinctly around Hanoi and Ho Chi Minh City. However, the nature of the relationship between genetic divergence and geographic patterns is still unclear.In this study, we hypothesized that genetic distances between H5N1 viruses in Vietnam are correlated with geographic distances, as the result of distinct population and environment patterns along Vietnam's long north to south longitudinal extent. Based on this hypothesis, we combined spatial statistical methods with genetic analytic techniques and explicitly used geographic space to explore genetic evolution of H5N1 highly pathogenic avian influenza viruses at the sub-national scale in Vietnam. Our dataset consisted of 125 influenza viruses (with whole genome sets isolated in Vietnam from 2003 to 2007. Our results document the significant effect of space and time on genetic evolution and the rise of two regional centers of genetic mixing by 2007. These findings give insight into processes underlying viral evolution and suggest that genetic differentiation is associated with the distance between concentrations of human and poultry populations around Hanoi and Ho Chi Minh City.The results show that genetic evolution of H5N1 viruses in Vietnamese domestic poultry is highly correlated with the location and spread of those viruses in geographic space. This correlation varies by scale, time, and gene, though a classic
Fátima Mitiko TENGAN
Full Text Available In order to contribute to a better understanding of the forms of acquisition of hepatitis C virus (HCV in Brazil, with special emphasis on sexual transmission, we determined the presence of HCV infection in regular partners and in non-sexual home communicants of blood donors seen at Fundação Pró-Sangue Hemocentro de São Paulo from January 1992 to July 1996. Of 154 blood donors with HCV infection (index cases, 111 had had regular partners for at least 6 months. Sixty-eight of 111 partners were evaluated for HCV infection. Of these, 8 (11.76% were considered to have current or previous HCV infection; a history of sexually transmissible diseases and index cases with a positive HCV-RNA test were more prevalent among partners with HCV infection. Of the 68 index cases whose partners were studied, 56 had non-sexual home communicants. Of the total of 81 home communicants, 66 accepted to be evaluated for HCV infection. None of them was HCV-positive, suggesting that the high prevalence of HCV infection among partners may be attributed at least partially to sexual transmission.
Van H. Pham
Conclusions: Measles viruses responsible for outbreaks in Southern Vietnam belonged to a genotype D8 variant group which had unique amino acid sequences in the N gene. Our report provides important genomic information about the virus for measles elimination in Southeast Asia.
Mai T Q Le
Full Text Available Prior to 2007, highly pathogenic avian influenza (HPAI H5N1 viruses isolated from poultry and humans in Vietnam were consistently reported to be clade 1 viruses, susceptible to oseltamivir but resistant to amantadine. Here we describe the re-emergence of human HPAI H5N1 virus infections in Vietnam in 2007 and the characteristics of the isolated viruses.Respiratory specimens from patients suspected to be infected with avian influenza in 2007 were screened by influenza and H5 subtype specific polymerase chain reaction. Isolated H5N1 strains were further characterized by genome sequencing and drug susceptibility testing. Eleven poultry outbreak isolates from 2007 were included in the sequence analysis. Eight patients, all of them from northern Vietnam, were diagnosed with H5N1 in 2007 and five of them died. Phylogenetic analysis of H5N1 viruses isolated from humans and poultry in 2007 showed that clade 2.3.4 H5N1 viruses replaced clade 1 viruses in northern Vietnam. Four human H5N1 strains had eight-fold reduced in-vitro susceptibility to oseltamivir as compared to clade 1 viruses. In two poultry isolates the I117V mutation was found in the neuraminidase gene, which is associated with reduced susceptibility to oseltamivir. No mutations in the M2 gene conferring amantadine resistance were found.In 2007, H5N1 clade 2.3.4 viruses replaced clade 1 viruses in northern Vietnam and were susceptible to amantadine but showed reduced susceptibility to oseltamivir. Combination antiviral therapy with oseltamivir and amantadine for human cases in Vietnam is recommended.
Schrauwen, Eefje JA; Fouchier, Ron AM
A wide range of influenza A viruses of pigs and birds have infected humans in the last decade, sometimes with severe clinical consequences. Each of these so-called zoonotic infections provides an opportunity for virus adaptation to the new host. Fortunately, most of these human infections do not yield viruses with the ability of sustained human-to-human transmission. However, animal influenza viruses have acquired the ability of sustained transmission between humans to cause pandemics on rare occasions in the past, and therefore, influenza virus zoonoses continue to represent threats to public health. Numerous recent studies have shed new light on the mechanisms of adaptation and transmission of avian and swine influenza A viruses in mammals. In particular, several studies provided insights into the genetic and phenotypic traits of influenza A viruses that may determine airborne transmission. Here, we summarize recent studies on molecular determinants of virulence and adaptation of animal influenza A virus and discuss the phenotypic traits associated with airborne transmission of newly emerging influenza A viruses. Increased understanding of the determinants and mechanisms of virulence and transmission may aid in assessing the risks posed by animal influenza viruses to human health, and preparedness for such risks. PMID:26038511
Conclusions: The transmissibility of Zika virus infection appears to be comparable to those of dengue and chikungunya viruses. Considering that Aedes species are a shared vector, this finding indicates that Zika virus replication within the vector is perhaps comparable to dengue and chikungunya.
Takakuwa, Hiroki; Yamashiro, Tetsu; Le, Mai Q; Phuong, Lien S; Ozaki, Hiroichi; Tsunekuni, Ryota; Usui, Tatsufumi; Ito, Hiroshi; Yamaguchi, Tsuyoshi; Ito, Toshihiro; Murase, Toshiyuki; Ono, Etsuro; Otsuki, Koichi
Due to concerns that wild birds could possibly spread H5N1 viruses, surveillance was conducted to monitor the types of avian influenza viruses circulating among the wild birds migrating to or inhabiting in northern Vietnam from 2006 to 2009. An H5N2 virus isolated from a Eurasian woodcock had a close phylogenetic relationship to H5 viruses recently isolated in South Korea and Japan, suggesting that H5N2 has been shared between Vietnam, South Korea, and Japan. An H9N2 virus isolated from a Chinese Hwamei was closely related to two H9N2 viruses that were isolated from humans in Hong Kong in 2009, suggesting that an H9N2 strain relevant to the human isolates had been transmitted to and maintained among the wild bird population in Vietnam and South China. The results support the idea that wild bird species play a significant role in the spread and maintenance of avian influenza and that this also occurs in Vietnam. Copyright © 2013 Elsevier Ltd. All rights reserved.
Kamenova, I.; Lohuis, H.; Peters, D.
The aphid transmissibility of seven Plum pox virus (PPV) isolates and the amino acid sequences of their coat proteins were analysed Two aphid transmissible isolates PPV-A and PPV-P contained the DAG amino triplet, while DAL or NAG replaced this triplet in the coat proteins of non-aphid transmissible
Vu, Le T; Long, Ngo T; Brito, Barbara; Stenfeldt, Carolina; Phuong, Nguyen T; Hoang, Bui H; Pauszek, Steven J; Hartwig, Ethan J; Smoliga, George R; Vu, Pham P; Quang, Le T V; Hung, Vo V; Tho, Nguyen D; Dong, Pham V; Minh, Phan Q; Bertram, Miranda; Fish, Ian H; Rodriguez, Luis L; Dung, Do H; Arzt, Jonathan
In recent years, foot-and-mouth disease virus (FMDV) serotype O, topotype Middle East-South Asia (ME-SA), lineage Ind-2001d has spread from the Indian subcontinent to the Middle East, North Africa, and Southeast Asia. In the current report, we describe the first detection of this lineage in Vietnam in May, 2015 in Đắk Nông province. Three subsequent outbreaks caused by genetically related viruses occurred between May-October, 2015 after which the virus was not detected in clinical outbreaks for at least 15 subsequent months. The observed outbreaks affected (in chronological order): cattle in Đắk Nông province, pigs in Đắk Lắk province and Đắk Nông province, and cattle in Ninh Thuận province. The clinical syndromes associated with these outbreaks were consistent with typical FMD in the affected species. Overall attack rate on affected premises was 0.85 in pigs and 0.93 in cattle over the course of the outbreak. Amongst 378 pigs at risk on affected premises, 85 pigs died during the outbreaks; there were no deaths among cattle. The manner in which FMDV/O/ME-SA/Ind-2001d was introduced into Vietnam remains undetermined; however, movement of live cattle is the suspected route. This incursion has substantial implications for epidemiology and control of FMD in Southeast Asia.
Merrill, M H; Tenbroeck, C
In confirming Kelser's work on the transmission of equine encephalomyelitis of the western type by Aëdes aegypti it has been learned that the mosquitoes must be fed virus of high titer if positive results are to be secured. A period of from 4 to 5 days after feeding either on infected guinea pigs or on brain containing virus must elapse before the disease is transmitted by biting, but after this time transmission regularly results for a period of about 2 months. By inoculation, virus can be demonstrated in the bodies of infected mosquitoes for the duration of life. Although virus multiplies in the mosquitoes and is generally distributed in their bodies, repeated attempts to demonstrate it in the eggs from females known to be infected as well as in larvae, pupae, and adults from such eggs have been uniformly negative. Larvae have not taken up virus added to the water in which they were living. Male mosquitoes have been infected with virus by feeding but they have not transmitted the virus to normal females, nor have males transmitted the virus from infected to normal females. When virus of the eastern instead of the western type is used transmission experiments with Aëdes aegypti are negative. Apparently this virus is incapable of penetrating the intestinal mucosa of the mosquito. If, however, it is inoculated into the body cavity by needle puncture it persists and transmission experiments are positive.
Michiel van Boven
Full Text Available Accumulating infections of highly pathogenic H5N1 avian influenza in humans underlines the need to track the ability of these viruses to spread among humans. A human-transmissible avian influenza virus is expected to cause clusters of infections in humans living in close contact. Therefore, epidemiological analysis of infection clusters in human households is of key importance. Infection clusters may arise from transmission events from (i the animal reservoir, (ii humans who were infected by animals (primary human-to-human transmission, or (iii humans who were infected by humans (secondary human-to-human transmission. Here we propose a method of analysing household infection data to detect changes in the transmissibility of avian influenza viruses in humans at an early stage. The method is applied to an outbreak of H7N7 avian influenza virus in The Netherlands that was the cause of more than 30 human-to-human transmission events. The analyses indicate that secondary human-to-human transmission is plausible for the Dutch household infection data. Based on the estimates of the within-household transmission parameters, we evaluate the effectiveness of antiviral prophylaxis, and conclude that it is unlikely that all household infections can be prevented with current antiviral drugs. We discuss the applicability of our method for the detection of emerging human-to-human transmission of avian influenza viruses in particular, and for the analysis of within-household infection data in general.
Bengtsson, Linus; Lu, Xin; Liljeros, Fredrik; Thanh, Hoang Huy; Thorson, Anna
Survey data from men who have sex with men (MSM) in Asian cities indicate ongoing and drastic increases in HIV prevalence. It is unknown which behavioural factors are most important in driving these epidemics. We aimed to analyse detailed sexual behaviour data among MSM in Vietnam and to model HIV transmission using improved assumptions on sexual network structure. Vietnam. Internet-using men who had ever had sex (any type) with a man, aged ≥18 years and living in Vietnam. The study was cross-sectional, population-based and performed in 2012, using online respondent-driven sampling. The Internet-based survey instrument was completed by 982 participants, of which 857 were eligible. Questions included sociodemography and retrospective sexual behaviour, including number of unprotected anal sex (UAS) acts per partner. Estimated basic reproductive number over 3 months as a function of transmission risk per UAS act; frequency distributions of number of UAS partners and UAS acts during last 3 months. 36% (CI 32% to 42%) reported UAS at least once during the last 3 months. 36% (CI 32% to 41%) had ever taken an HIV test and received the result. UAS partner numbers and number of UAS acts were both highly skewed and positively correlated. Using a weighted configuration model, taking into account partner numbers, frequency of UAS and their correlations, we estimated the basic reproductive number (R0) over 3 months. The results indicated rapid transmission over a wide range of values of per-act transmissibility. Men with multiple partners had unexpectedly high UAS frequency per partner, paired with low HIV testing rates. The study highlights the importance of collecting data on frequency of UAS acts and indicates the need to rapidly scale-up HIV prevention services and testing opportunities for MSM in Vietnam.
Takemae, Nobuhiro; Harada, Michiyo; Nguyen, Phuong Thanh; Nguyen, Tung; Nguyen, Tien Ngoc; To, Thanh Long; Nguyen, Tho Dang; Pham, Vu Phong; Le, Vu Tri; Do, Hoa Thi; Vo, Hung Van; Le, Quang Vinh Tin; Tran, Tan Minh; Nguyen, Thanh Duy; Thai, Phuong Duy; Nguyen, Dang Hoang; Le, Anh Quynh Thi; Nguyen, Diep Thi; Uchida, Yuko; Saito, Takehiko
Active surveillance of influenza A viruses of swine (IAV-S) involving 262 farms and 10 slaughterhouses in seven provinces in northern and southern Vietnam from 2010 to 2015 yielded 388 isolates from 32 farms; these viruses were classified into H1N1, H1N2, and H3N2 subtypes. Whole-genome sequencing followed by phylogenetic analysis revealed that the isolates represented 15 genotypes, according to the genetic constellation of the eight segments. All of the H1N1 viruses were entirely A(H1N1)pdm09 viruses, whereas all of the H1N2 and H3N2 viruses were reassortants among 5 distinct ancestral viruses: H1 and H3 triple-reassortant (TR) IAV-S that originated from North American pre-2009 human seasonal H1, human seasonal H3N2, and A(H1N1)pdm09 viruses. Notably, 93% of the reassortant IAV-S retained M genes that were derived from A(H1N1)pdm09, suggesting some advantage in terms of their host adaptation. Bayesian Markov chain Monte Carlo analysis revealed that multiple introductions of A(H1N1)pdm09 and TR IAV-S into the Vietnamese pig population have driven the genetic diversity of currently circulating Vietnamese IAV-S. In addition, our results indicate that a reassortant IAV-S with human-like H3 and N2 genes and an A(H1N1)pdm09 origin M gene likely caused a human case in Ho Chi Minh City in 2010. Our current findings indicate that human-to-pig transmission as well as cocirculation of different IAV-S have contributed to diversifying the gene constellations of IAV-S in Vietnam. This comprehensive genetic characterization of 388 influenza A viruses of swine (IAV-S) isolated through active surveillance of Vietnamese pig farms from 2010 through 2015 provides molecular epidemiological insight into the genetic diversification of IAV-S in Vietnam after the emergence of A(H1N1)pdm09 viruses. Multiple reassortments among A(H1N1)pdm09 viruses and enzootic IAV-S yielded 14 genotypes, 9 of which carried novel gene combinations. The reassortants that carried M genes derived from A(H1N1
Le, Van Phan; Vu, Thi Thu Hang; Duong, Hong-Quan; Than, Van Thai; Song, Daesub
Foot-and-mouth disease virus (FMDV) is one of the highest risk factors that affects the animal industry of the country. The virus causes production loss and high ratio mortality in young cloven-hoofed animals in Vietnam. The VP1 coding gene of 80 FMDV samples (66 samples of the serotype O and 14 samples of the serotype A) collected from endemic outbreaks during 2006-2014 were analyzed to investigate their phylogeny and genetic relationship with other available FMDVs globally. Phylogenetic analysis indicated that the serotype O strains were clustered into two distinct viral topotypes (the SEA and ME-SA), while the serotype A strains were all clustered into the genotype IX. Among the study strains, the amino acid sequence identities were shared at a level of 90.1-100, 92.9-100, and 92.8-100% for the topotypes SEA, ME-SA, and genotype IX, respectively. Substitutions leading to changes in the amino acid sequence, which are critical for the VP1 antigenic sites were also identified. Our results showed that the studied strains are most closely related to the recent FMDV isolates from Southeast Asian countries (Myanmar, Thailand, Cambodia, Malaysia, and Laos), but are distinct from the earlier FMDV isolates within the genotypes. This study provides important evidence of recent movement of FMDVs serotype O and A into Vietnam within the last decade and their genetic accumulation to be closely related to strains causing FMD in surrounding countries.
Roundy, Christopher M; Azar, Sasha R; Rossi, Shannan L; Huang, Jing H; Leal, Grace; Yun, Ruimei; Fernandez-Salas, Ildefonso; Vitek, Christopher J; Paploski, Igor A D; Kitron, Uriel; Ribeiro, Guilherme S; Hanley, Kathryn A; Weaver, Scott C; Vasilakis, Nikos
To test whether Zika virus has adapted for more efficient transmission by Aedes aegypti mosquitoes, leading to recent urban outbreaks, we fed mosquitoes from Brazil, the Dominican Republic, and the United States artificial blood meals containing 1 of 3 Zika virus strains (Senegal, Cambodia, Mexico) and monitored infection, dissemination, and virus in saliva. Contrary to our hypothesis, Cambodia and Mexica strains were less infectious than the Senegal strain. Only mosquitoes from the Dominican Republic transmitted the Cambodia and Mexica strains. However, blood meals from viremic mice were more infectious than artificial blood meals of comparable doses; the Cambodia strain was not transmitted by mosquitoes from Brazil after artificial blood meals, whereas 61% transmission occurred after a murine blood meal (saliva titers up to 4 log 10 infectious units/collection). Although regional origins of vector populations and virus strain influence transmission efficiency, Ae. aegypti mosquitoes appear to be competent vectors of Zika virus in several regions of the Americas.
Pica, Natalie; Chou, Yi-Ying; Bouvier, Nicole M.
Epidemic influenza is typically caused by infection with viruses of the A and B types and can result in substantial morbidity and mortality during a given season. Here we demonstrate that influenza B viruses can replicate in the upper respiratory tract of the guinea pig and that viruses of the two main lineages can be transmitted with 100% efficiency between inoculated and naïve animals in both contact and noncontact models. Our results also indicate that, like in the case for influenza A virus, transmission of influenza B viruses is enhanced at colder temperatures, providing an explanation for the seasonality of influenza epidemics in temperate climates. We therefore present, for the first time, a small animal model with which to study the underlying mechanisms of influenza B virus transmission. PMID:22301149
Carrel, Margaret; Wan, Xiu-Feng; Nguyen, Tung; Emch, Michael
Locating areas where genetic change is inhibited can illuminate underlying processes that drive evolution of pathogens. The persistence of highly pathogenic H5N1 avian influenza in Vietnam since 2003, and the continuous molecular evolution of Vietnamese avian influenza viruses, indicates that local environmental factors are supportive not only of incidence but also of viral adaptation. This article explores whether gene flow is constant across Vietnam, or whether there exist boundary areas where gene flow exhibits discontinuity. Using a dataset of 125 highly pathogenic H5N1 avian influenza viruses, principal components analysis and wombling analysis are used to indicate the location, magnitude, and statistical significance of genetic boundaries. Results show that a small number of geographically minor boundaries to gene flow in highly pathogenic H5N1 avian influenza viruses exist in Vietnam, but that overall there is little division in genetic exchange. This suggests that differences in genetic characteristics of viruses from one region to another are not the result of barriers to H5N1 viral exchange in Vietnam, and that H5N1 avian influenza is able to spread relatively unimpeded across the country. PMID:22350419
Vetter, Pauline; Fischer, William A; Schibler, Manuel; Jacobs, Michael; Bausch, Daniel G; Kaiser, Laurent
The magnitude of the 2013-2016 Ebola virus disease outbreak in West Africa was unprecedented, with >28 500 reported cases and >11 000 deaths. Understanding the key elements of Ebola virus transmission is necessary to implement adequate infection prevention and control measures to protect healthcare workers and halt transmission in the community. We performed an extensive PubMed literature review encompassing the period from discovery of Ebola virus, in 1976, until 1 June 2016 to evaluate the evidence on modes of Ebola virus shedding and transmission. Ebola virus has been isolated by cell culture from blood, saliva, urine, aqueous humor, semen, and breast milk from infected or convalescent patients. Ebola virus RNA has been noted in the following body fluids days or months after onset of illness: saliva (22 days), conjunctiva/tears (28 days), stool (29 days), vaginal fluid (33 days), sweat (44 days), urine (64 days), amniotic fluid (38 days), aqueous humor (101 days), cerebrospinal fluid (9 months), breast milk (16 months [preliminary data]), and semen (18 months). Nevertheless, the only documented cases of secondary transmission from recovered patients have been through sexual transmission. We did not find strong evidence supporting respiratory or fomite-associated transmission. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail email@example.com.
Boven, M. van; Koopmans, M.; Du Ry van Beest Holle, M.; Meijer, Adam; Klinkenberg, D.; Donnelly, C.A.; Heesterbeek, J.A.P.
Accumulating infections of highly pathogenic H5N1 avian influenza in humans underlines the need to track the ability of these viruses to spread among humans. A human-transmissible avian influenza virus is expected to cause clusters of infections in humans living in close contact. Therefore,
Boven, van R.M.; Koopmans, M.; Du Ry Beest Holle, van M.; Meijer, A.; Klinkenberg, D.; Donnelly, C.; Heesterbeek, J.A.P.
Accumulating infections of highly pathogenic H5N1 avian influenza in humans underlines the need to track the ability of these viruses to spread among humans. A human-transmissible avian influenza virus is expected to cause clusters of infections in humans living in close contact. Therefore,
Knowledge of the transmission of highly pathogenic avian influenza (HPAI) virus still has gaps, complicating epidemic control. A model was developed to back-calculate the day HPAI virus was introduced into a flock, based on within-flock mortality data of the Dutch HPAI H7N7 epidemic (2003). The
van der Sluijs, Mirjam Tineke Willemijn; de Smit, Abraham J; Moormann, Rob J M
Bluetongue is an economically important disease of ruminants. The causative agent, Bluetongue virus (BTV), is mainly transmitted by insect vectors. This review focuses on vector-free BTV transmission, and its epizootic and economic consequences. Vector-free transmission can either be vertical, from dam to fetus, or horizontal via direct contract. For several BTV-serotypes, vertical (transplacental) transmission has been described, resulting in severe congenital malformations. Transplacental transmission had been mainly associated with live vaccine strains. Yet, the European BTV-8 strain demonstrated a high incidence of transplacental transmission in natural circumstances. The relevance of transplacental transmission for the epizootiology is considered limited, especially in enzootic areas. However, transplacental transmission can have a substantial economic impact due to the loss of progeny. Inactivated vaccines have demonstrated to prevent transplacental transmission. Vector-free horizontal transmission has also been demonstrated. Since direct horizontal transmission requires close contact of animals, it is considered only relevant for within-farm spreading of BTV. The genetic determinants which enable vector-free transmission are present in virus strains circulating in the field. More research into the genetic changes which enable vector-free transmission is essential to better evaluate the risks associated with outbreaks of new BTV serotypes and to design more appropriate control measures.
Vesicular Stomatitis (VS) is caused by the Vesicular Stomatitis Virus (VSV), a negative single stranded RNA arthropod-borne virus member of the Family Rhabdoviridae. The virion is composed of the host derived plasma membrane, the envelope, and an internal ribonucleoprotein core. The envelope contain...
Milazzo, Mary L.; Cajimat, Maria N.B.; Duno, Gloria; Duno, Freddy; Utrera, Antonio
Samples from rodents captured on a farm in Venezuela in February 1997 were tested for arenavirus, antibody against Guanarito virus (GTOV), and antibody against Pirital virus (PIRV). Thirty-one (48.4%) of 64 short-tailed cane mice (Zygodontomys brevicauda) were infected with GTOV, 1 Alston’s cotton rat (Sigmodon alstoni) was infected with GTOV, and 36 (64.3%) of 56 other Alston’s cotton rats were infected with PIRV. The results of analyses of field and laboratory data suggested that horizontal transmission is the dominant mode of GTOV transmission in Z. brevicauda mice and that vertical transmission is an important mode of PIRV transmission in S. alstoni rats. The results also suggested that bodily secretions and excretions from most GTOV-infected short-tailed cane mice and most PIRV-infected Alston’s cotton rats may transmit the viruses to humans. PMID:22172205
Benjamin J Cowling
Full Text Available While influenza A and B viruses can be transmitted via respiratory droplets, the importance of small droplet nuclei "aerosols" in transmission is controversial.In Hong Kong and Bangkok, in 2008-11, subjects were recruited from outpatient clinics if they had recent onset of acute respiratory illness and none of their household contacts were ill. Following a positive rapid influenza diagnostic test result, subjects were randomly allocated to one of three household-based interventions: hand hygiene, hand hygiene plus face masks, and a control group. Index cases plus their household contacts were followed for 7-10 days to identify secondary infections by reverse transcription polymerase chain reaction (RT-PCR testing of respiratory specimens. Index cases with RT-PCR-confirmed influenza B were included in the present analyses. We used a mathematical model to make inferences on the modes of transmission, facilitated by apparent differences in clinical presentation of secondary infections resulting from aerosol transmission. We estimated that approximately 37% and 26% of influenza B virus transmission was via the aerosol mode in households in Hong Kong and Bangkok, respectively. In the fitted model, influenza B virus infections were associated with a 56%-72% risk of fever plus cough if infected via aerosol route, and a 23%-31% risk of fever plus cough if infected via the other two modes of transmission.Aerosol transmission may be an important mode of spread of influenza B virus. The point estimates of aerosol transmission were slightly lower for influenza B virus compared to previously published estimates for influenza A virus in both Hong Kong and Bangkok. Caution should be taken in interpreting these findings because of the multiple assumptions inherent in the model, including that there is limited biological evidence to date supporting a difference in the clinical features of influenza B virus infection by different modes.
Linard, Catherine; Tersago, Katrien; Leirs, Herwig
of this study is to better understand the causal link between environmental features and PUUV prevalence in bank vole population in Belgium, and hence with transmission risk to humans. Our hypothesis was that environmental conditions controlling the direct and indirect transmission paths differ....... Based on logistic regressions, we show that PUUV prevalence among bank voles is more linked to variables favouring the survival of the virus in the environment, and thus the indirect transmission: low winter temperatures are strongly linked to prevalence among bank voles, and high soil moisture...... is linked to the number of NE cases among humans. The transmission risk to humans therefore depends on the efficiency of the indirect transmission path. Human risk behaviours, such as the propensity for people to go in forest areas that best support the virus, also influence the number of human cases...
Introduction: Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections in hemodialysis (HD) patients are associated with adverse outcomes, especially after kidney transplantation. Review: In the HD setting, cross-contamination to patients via environmental surfaces, supplies, equipment, multiple-dose medication vials ...
sex, and social status with the subjects served as control. Voluntary counseling ... to HIV antibody. Conclusions: Blood transfusion is still a risk factor for HIV transmission .... 1.6% documented by Al-Mahroos and Ebrahim in Bahrain. Island.
Nitwara Wikan; Yupin Suputtamongkol; Sutee Yoksan; Duncan R. Smith; Prasert Auewarakul
Objective: To identify immunological evidence of Zika virus transmission in Thailand. Methods: To undertake a preliminary serosurvey of possible exposure to Zika virus, 21 serum samples from cohort of acute undifferentiated fever patients were examined for immunoreactivity to Zika, Dengue, Japanese encephalitis and Chikungunya envelope antigens by Western blot analysis. Results: Twenty of the 21 serum samples showed immunoreactivity to at least one of the antigens, with seven samples showing immunoreactivity to all antigens. Of particular note, two serum samples showed immunoreactivity only to Zika envelope antigen, with no immunoreactivity to other envelope antigens. Conclusions: This study presents the first evidence of Zika virus transmission in Thailand, although as yet the relationship between transmission and possible cases of Zika fever in Thailand requires further investigation.
Erin M McDonald
Full Text Available The Spondweni serogroup of viruses (Flaviviridae, Flavivirus is comprised of Spondweni virus (SPONV and Zika virus (ZIKV, which are mosquito-borne viruses capable of eliciting human disease. Numerous cases of ZIKV sexual transmission in humans have been documented following the emergence of the Asian genotype in the Americas. The African ZIKV genotype virus was previously implicated in the first reported case of ZIKV sexual transmission. Reports of SPONV infection in humans have been associated with non-specific febrile illness, but no association with sexual transmission has been reported. In order to assess the relative efficiency of sexual transmission of different ZIKV strains and the potential capacity of SPONV to be sexually transmitted, viral loads in the male reproductive tract and in seminal fluids were assessed in interferon α/β and -γ receptor deficient (AG129 mice. Male mice were inoculated subcutaneously with Asian genotype ZIKV strains PRVABC59 (Puerto Rico, 2015, FSS13025 (Cambodia, 2010, or P6-740 (Malaysia, 1966; African genotype ZIKV strain DakAr41524 (Senegal, 1984; or SPONV strain SAAr94 (South Africa, 1955. Infectious virus was detected in 60-72% of ejaculates collected from AG129 mice inoculated with ZIKV strains. In contrast, only 4% of ejaculates from SPONV-inoculated AG129 males were found to contain infectious virus, despite viral titers in the testes that were comparable to those of ZIKV-inoculated mice. Based on these results, future studies should be undertaken to assess the role of viral genetic determinants and host tropism that dictate the differential sexual transmission potential of ZIKV and SPONV.
Auguste, Albert J; Lemey, Philippe; Bergren, Nicholas A; Giambalvo, Dileyvic; Moncada, Maria; Morón, Dulce; Hernandez, Rosa; Navarro, Juan-Carlos; Weaver, Scott C
Phylogenetic analysis of yellow fever virus (YFV) strains isolated from Venezuela strongly supports YFV maintenance in situ in Venezuela, with evidence of regionally independent evolution within the country. However, there is considerable YFV movement from Brazil to Venezuela and between Trinidad and Venezuela.
Creanga, Adrian; Thi Nguyen, Diep; Gerloff, Nancy; Thi Do, Hoa; Balish, Amanda; Dang Nguyen, Hoang; Jang, Yunho; Thi Dam, Vui; Thor, Sharmi; Jones, Joyce; Simpson, Natosha; Shu, Bo; Emery, Shannon; Berman, LaShondra; Nguyen, Ha T; Bryant, Juliet E; Lindstrom, Steve; Klimov, Alexander; Donis, Ruben O; Davis, C Todd; Nguyen, Tung
Phylogenetic analyses of 169 influenza A(H5N1) virus genomes were conducted for samples collected through active surveillance and outbreak responses in Vietnam between September 2010 and September 2012. While clade 1.1 viruses persisted in southern regions, three genetically distinct subgroups of clade 18.104.22.168 were found in northern and central Vietnam. The identification of each subgroup corresponded with detection of novel reassortants, likely due to their overlapping circulation throughout the country. While the previously identified clade 1.1 and A/Hubei/1/2010-like 22.214.171.124 genotypes remained the predominant viruses detected, four viruses were found to be reassortants between A/Hubei/1/2010-like (HA, NA, PB2, PB1, PA, NP) and A/duck/Vietnam/NCVD-885/2010-like (M, NS) viruses and one virus was identified as having A/duck/Vietnam/NCVD-885/2010-like HA, NA, PB1, and NP with A/Hubei/1/2010-like PB2 and PA genes. Additionally, clade 126.96.36.199 A/Hong Kong/6841/2010-like viruses, first detected in mid-2012, were identified as reassortants comprised of A/Hubei/1/2010-like PB2 and PA and A/duck/Vietnam/NCVD-885/2010-like PB1, NP, NA, M, NS genes. Published by Elsevier Inc.
Lowery, D Thomas; Vickers, Patricia M; Bittner, Lori A; Stobbs, Lorne W; Foottit, Robert G
Utilization of timed virus acquisition access probes in studies of plum pox virus (PPV) transmission by aphids demonstrated that endemic species transmitted the virus readily from plum, Prunus domestica (L.) Batsch; peach, P. persica (L.); or dwarf flowering almond, P. glandulosa Thunberg., to peach seedlings. The green peach aphid, Myzus persicae (Sulzer), was shown to be the most efficient vector. Acquisition of virus by green peach aphids from infected peach leaves resulted in 18-28% infected peach seedlings, while aphids previously fed on infected leaves of plum transferred virus to 36% of peach seedlings. Although the spirea aphid, Aphis spiraecola (Patch), was a less efficient vector than M. persicae it is perhaps more important for the spread of PPV due to its greater abundance and occurrence earlier in the season when peach trees are thought to be more susceptible to infection. Virus transmission rates varied depending on the virus source and healthy test plant species. In contrast to many previous studies, aphid inoculation of the experimental host Nicotiana benthamiana Domin occurred at a low rate, never exceeding 4%. Acquisition of PPV by M. persicae from infected peach fruit was greatly reduced compared with acquisition from leaves. The results of this research indicate that the Ontario isolate of PPV-D is readily transmissible by aphids to peach and natural spread of the virus needs to be considered in future management or eradication programs. © Her Majesty in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada. Published by Oxford University Press on behalf of Entomological Society of America.
Christina L Hutson
Full Text Available Monkeypox virus (MPXV is endemic within Africa where it sporadically is reported to cause outbreaks of human disease. In 2003, an outbreak of human MPXV occurred in the US after the importation of infected African rodents. Since the eradication of smallpox (caused by an orthopoxvirus (OPXV related to MPXV and cessation of routine smallpox vaccination (with the live OPXV vaccinia, there is an increasing population of people susceptible to OPXV diseases. Previous studies have shown that the prairie dog MPXV model is a functional animal model for the study of systemic human OPXV illness. Studies with this model have demonstrated that infected animals are able to transmit the virus to naive animals through multiple routes of exposure causing subsequent infection, but were not able to prove that infected animals could transmit the virus exclusively via the respiratory route. Herein we used the model system to evaluate the hypothesis that the Congo Basin clade of MPXV is more easily transmitted, via respiratory route, than the West African clade. Using a small number of test animals, we show that transmission of viruses from each of the MPXV clade was minimal via respiratory transmission. However, transmissibility of the Congo Basin clade was slightly greater than West African MXPV clade (16.7% and 0% respectively. Based on these findings, respiratory transmission appears to be less efficient than those of previous studies assessing contact as a mechanism of transmission within the prairie dog MPXV animal model.
Vinh, Hoang Quang; Phimpraphai, Waraphon; Tangkawattana, Sirikachorn; Smith, John F; Kaewkes, Sasithorn; Dung, Do Trung; Duong, Tran Thanh; Sripa, Banchob
Clonorchis sinensis is major fish-borne trematode, endemic in North Vietnam. Risk factors described so far include individual eating behaviors and environmental factors. Here, additional to conventional risk factors, we report on socially influenced liver fluke transmission in endemic communities. A cross-sectional study on risk factors and fish sharing networks was conducted in 4 villages of Gia Thinh Commune, Ninh Binh Province. A total of 510 residents in 272 households were recruited for risk factor analysis while 220 households, 28 fishermen and 10 fish-sellers were enrolled for social network study. Fecal examination for C. sinensis eggs was performed. Average C. sinensis infection rate at Gia Thinh commune was 16.5% (range 2% to 34.4%). Higher infection rates were significantly associated with males, lower educational levels, eating raw fish, and location of the villages. Social network analysis (SNA) showed a strong positive correlation between ego network size (number of households in fish sharing network) and quantity of raw fish consumed (r=0.603, Psinensis infection transmission in northern Vietnam. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Christie, Athalia; Davies-Wayne, Gloria J; Cordier-Lassalle, Thierry; Cordier-Lasalle, Thierry; Blackley, David J; Laney, A Scott; Williams, Desmond E; Shinde, Shivam A; Badio, Moses; Lo, Terrence; Mate, Suzanne E; Ladner, Jason T; Wiley, Michael R; Kugelman, Jeffrey R; Palacios, Gustavo; Holbrook, Michael R; Janosko, Krisztina B; de Wit, Emmie; van Doremalen, Neeltje; Munster, Vincent J; Pettitt, James; Schoepp, Randal J; Verhenne, Leen; Evlampidou, Iro; Kollie, Karsor K; Sieh, Sonpon B; Gasasira, Alex; Bolay, Fatorma; Kateh, Francis N; Nyenswah, Tolbert G; De Cock, Kevin M
On March 20, 2015, 30 days after the most recent confirmed Ebola Virus Disease (Ebola) patient in Liberia was isolated, Ebola was laboratory confirmed in a woman in Monrovia. The investigation identified only one epidemiologic link to Ebola: unprotected vaginal intercourse with a survivor. Published reports from previous outbreaks have demonstrated Ebola survivors can continue to harbor virus in immunologically privileged sites for a period of time after convalescence. Ebola virus has been isolated from semen as long as 82 days after symptom onset and viral RNA has been detected in semen up to 101 days after symptom onset. One instance of possible sexual transmission of Ebola has been reported, although the accompanying evidence was inconclusive. In addition, possible sexual transmission of Marburg virus, a filovirus related to Ebola, was documented in 1968. This report describes the investigation by the Government of Liberia and international response partners of the source of Liberia's latest Ebola case and discusses the public health implications of possible sexual transmission of Ebola virus. Based on information gathered in this investigation, CDC now recommends that contact with semen from male Ebola survivors be avoided until more information regarding the duration and infectiousness of viral shedding in body fluids is known. If male survivors have sex (oral, vaginal, or anal), a condom should be used correctly and consistently every time.
Zaaijer, H. L.; Appelman, P.; Frijstein, G.
Hepatitis C virus (HCV)-infected physicians have been reported to infect some of their patients during exposure-prone procedures (EPPs). There is no European consensus on the policy for the prevention of this transmission. To help define an appropriate preventive policy, we determined the prevalence
Jatropha curcas, a plant with great biodiesel potential is also used to reduce the population of whiteflies, Bemisia tabaci on cassava fields when planted as a hedge. We therefore, investigated the transmission of African cassava mosaic virus (ACMV) by the whitefly vector from cassava to seedlings of 10 accessions of J.
Trung, N.V.; Matamoros, S.; Carrique-Mas, J.J.; Nghia, N.H.; Nhung, N.T.; Chieu, T.T.B.; Mai, H.H.; Van Rooijen, W.; Campbell, J.; Wagenaar, J.A.; Hardon, A.; Mai, N.T.N.; Hieu, T.Q.; Thwaites, G.; de Jong, M.D.; Schultsz, C.; Hoa, N.T.
We investigated the consequences of colistin use in backyard chicken farms in Vietnam by examining the prevalence of mcr-1 in fecal samples from chickens and humans. Detection of mcr-1–carrying bacteria in chicken samples was associated with colistin use and detection in human samples with exposure
Trung, Nguyen Vinh; Matamoros, Sébastien; Carrique-Mas, Juan J.; Nghia, Nguyen Huu; Nhung, Nguyen Thi; Chieu, Tran Thi Bich; Mai, Ho Huynh; van Rooijen, Willemien; Campbell, James; Wagenaar, Jaap A.; Hardon, Anita; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Thwaites, Guy; de Jong, Menno D.; Schultsz, Constance; Hoa, Ngo Thi
We investigated the consequences of colistin use in backyard chicken farms in Vietnam by examining the prevalence of mcr-1 in fecal samples from chickens and humans. Detection of mcr-1-carrying bacteria in chicken samples was associated with colistin use and detection in human samples with exposure
Nishiura, Hiroshi; Kinoshita, Ryo; Mizumoto, Kenji; Yasuda, Yohei; Nah, Kyeongah
Zika virus has spread internationally through countries in the South Pacific and Americas. The present study aimed to estimate the basic reproduction number, R0, of Zika virus infection as a measurement of the transmission potential, reanalyzing past epidemic data from the South Pacific. Incidence data from two epidemics, one on Yap Island, Federal State of Micronesia in 2007 and the other in French Polynesia in 2013-2014, were reanalyzed. R0 of Zika virus infection was estimated from the early exponential growth rate of these two epidemics. The maximum likelihood estimate (MLE) of R0 for the Yap Island epidemic was in the order of 4.3-5.8 with broad uncertainty bounds due to the small sample size of confirmed and probable cases. The MLE of R0 for French Polynesia based on syndromic data ranged from 1.8 to 2.0 with narrow uncertainty bounds. The transmissibility of Zika virus infection appears to be comparable to those of dengue and chikungunya viruses. Considering that Aedes species are a shared vector, this finding indicates that Zika virus replication within the vector is perhaps comparable to dengue and chikungunya. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.
Phan, T G; Nguyen, T A; Yan, H; Okitsu, S; Ushijima, H
A novel reverse transcription-multiplex polymerase chain reaction (RT-multiplex PCR) assay that can detect enteroviruses, hepatitis A and E viruses and influenza A virus from various hosts (avian species, human, swine and horse) was developed. The identification of that group of viruses was performed with the mixture of four pairs of published specific primers (F1 and R1, P3 and P4, 2s and 2as, MMU42 and MMU43) for amplifying viral genomes and specifically generated four different amplicon sizes of 440, 267, 146 and 219 bp for enteroviruses, hepatitis A and E viruses and influenza A virus, respectively. A total of 276 fecal specimens (previously screened for rotavirus, adenovirus, norovirus, sapovirus and astrovirus-negative) from infants and children admitted into hospital with acute gastroenteritis in Ho Chi Minh city, Vietnam during October 2002 and September 2003 were collected and further tested for the presence of those viruses by RT-multiplex PCR. Enteroviruses were identified in 27 specimens and this represented 9.8%. No hepatitis A and E viruses and influenza A virus was found among these subjects. The sensitivity and specificity of RT-multiplex PCR were also assessed and demonstrated the strong validation against RT-monoplex PCR. Taken together, the findings clearly indicated that this novel RT-multiplex PCR is a simple and potential assay for rapid, sensitive, specific and cost-effective laboratory diagnosis to investigate molecular epidemiology of acute gastroenteritis caused by enteroviruses, hepatitis A and E viruses and influenza A virus. This report is the first, to our knowledge, detecting these kinds of viruses in diarrheal feces from infants and children in Vietnam.
Blackley, David J; Wiley, Michael R; Ladner, Jason T; Fallah, Mosoka; Lo, Terrence; Gilbert, Merle L; Gregory, Christopher; D'ambrozio, Jonathan; Coulter, Stewart; Mate, Suzanne; Balogun, Zephaniah; Kugelman, Jeffrey; Nwachukwu, William; Prieto, Karla; Yeiah, Adolphus; Amegashie, Fred; Kearney, Brian; Wisniewski, Meagan; Saindon, John; Schroth, Gary; Fakoli, Lawrence; Diclaro, Joseph W; Kuhn, Jens H; Hensley, Lisa E; Jahrling, Peter B; Ströher, Ute; Nichol, Stuart T; Massaquoi, Moses; Kateh, Francis; Clement, Peter; Gasasira, Alex; Bolay, Fatorma; Monroe, Stephan S; Rambaut, Andrew; Sanchez-Lockhart, Mariano; Scott Laney, A; Nyenswah, Tolbert; Christie, Athalia; Palacios, Gustavo
On 29 June 2015, Liberia's respite from Ebola virus disease (EVD) was interrupted for the second time by a renewed outbreak ("flare-up") of seven confirmed cases. We demonstrate that, similar to the March 2015 flare-up associated with sexual transmission, this new flare-up was a reemergence of a Liberian transmission chain originating from a persistently infected source rather than a reintroduction from a reservoir or a neighboring country with active transmission. Although distinct, Ebola virus (EBOV) genomes from both flare-ups exhibit significantly low genetic divergence, indicating a reduced rate of EBOV evolution during persistent infection. Using this rate of change as a signature, we identified two additional EVD clusters that possibly arose from persistently infected sources. These findings highlight the risk of EVD flare-ups even after an outbreak is declared over.
Several FMDV carrier cattle were identified in Vietnam by recovery of infectious virus from oropharyngeal fluid. This report contains the first near-complete genome sequences of seven viruses isolated from a single carrier animal over the course of one year. Understanding within-host viral evolution...
Full Text Available Zika is a flavivirus transmitted to humans through either the bites of infected Aedes mosquitoes or sexual transmission. Zika has been linked to congenital anomalies such as microcephaly. In this paper, we analyze a new system of ordinary differential equations which incorporates human vertical transmission of Zika virus, the birth of babies with microcephaly and asymptomatically infected individuals. The Zika model is locally and globally asymptotically stable when the basic reproduction number is less than unity. Our model shows that asymptomatic individuals amplify the disease burden in the community, and the most important parameters for ZIKV spread are the death rate of mosquitoes, the mosquito biting rate, the mosquito recruitment rate, and the transmission per contact to mosquitoes and to adult humans. Scenario exploration indicates that personal-protection is a more effective control strategy than mosquito-reduction strategy. It also shows that delaying conception reduces the number of microcephaly cases, although this does little to prevent Zika transmission in the broader community. However, by coupling aggressive vector control and personal protection use, it is possible to reduce both microcephaly and Zika transmission. 2000 Mathematics Subject Classifications: 92B05, 93A30, 93C15. Keywords: Zika virus, Vertical transmission, Microcephaly, Stability, Control
Keita, Mory; Duraffour, Sophie; Loman, Nicholas J.; Rambaut, Andrew; Diallo, Boubacar; Magassouba, Nfaly; Carroll, Miles W.; Quick, Joshua; Sall, Amadou A.; Glynn, Judith R.; Formenty, Pierre; Faye, Ousmane
In October 2015, a new case of Ebola virus disease in Guinea was detected. Case investigation, serology, and whole-genome sequencing indicated possible transmission of the virus from an Ebola virus disease survivor to another person and then to the case-patient reported here. This transmission chain over 11 months suggests slow Ebola virus evolution. PMID:27869596
Keita, Mory; Duraffour, Sophie; Loman, Nicholas J; Rambaut, Andrew; Diallo, Boubacar; Magassouba, Nfaly; Carroll, Miles W; Quick, Joshua; Sall, Amadou A; Glynn, Judith R; Formenty, Pierre; Subissi, Lorenzo; Faye, Ousmane
In October 2015, a new case of Ebola virus disease in Guinea was detected. Case investigation, serology, and whole-genome sequencing indicated possible transmission of the virus from an Ebola virus disease survivor to another person and then to the case-patient reported here. This transmission chain over 11 months suggests slow Ebola virus evolution.
Gammeltoft, Tine; Rasch, Vibeke; Bui, Kim Chi
's faith in their futures and childbearing capacities. Based on the findings, the authors discuss the new forms of gendered uncertainty that arise in the era of HIV/AIDS in Vietnam. They conclude that prevention of mother-to-child transmission, including the counseling offered by health providers, plays...
Mohammad S. Khuroo
Full Text Available Hepatitis E virus (HEV, an RNA virus of the Hepeviridae family, has marked heterogeneity. While all five HEV genotypes can cause human infections, genotypes HEV-1 and -2 infect humans alone, genotypes HEV-3 and -4 primarily infect pigs, boars and deer, and genotype HEV-7 primarily infects dromedaries. The global distribution of HEV has distinct epidemiological patterns based on ecology and socioeconomic factors. In resource-poor countries, disease presents as large-scale waterborne epidemics, and few epidemics have spread through person-to-person contact; however, endemic diseases within these countries can potentially spread through person-to-person contact or fecally contaminated water and foods. Vertical transmission of HEV from infected mother to fetus causes high fetal and perinatal mortality. Other means of transmission, such as zoonotic transmission, can fluctuate depending upon the region and strain of the virus. For instance, zoonotic transmission can sometimes play an insignificant role in human infections, such as in India, where human and pig HEV infections are unrelated. However, recently China and Southeast Asia have experienced a zoonotic spread of HEV-4 from pigs to humans and this has become the dominant mode of transmission of hepatitis E in eastern China. Zoonotic HEV infections in humans occur by eating undercooked pig flesh, raw liver, and sausages; through vocational contact; or via pig slurry, which leads to environmental contamination of agricultural products and seafood. Lastly, blood transfusion-associated HEV infections occur in many countries and screening of donors for HEV RNA is currently under serious consideration. To summarize, HEV genotypes 1 and 2 cause epidemic and endemic diseases in resource poor countries, primarily spreading through contaminated drinking water. HEV genotypes 3 and 4 on the other hand, cause autochthonous infections in developed, and many developing countries, by means of a unique zoonotic
Hofmeister, Megan G; Foster, Monique A; Teshale, Eyasu H
There are many similarities in the epidemiology and transmission of hepatitis A virus (HAV) and hepatitis E virus (HEV) genotype (gt)3 infections in the United States. Both viruses are enterically transmitted, although specific routes of transmission are more clearly established for HAV than for HEV: HAV is restricted to humans and primarily spread through the fecal-oral route, while HEV is zoonotic with poorly understood modes of transmission in the United States. New cases of HAV infection have decreased dramatically in the United States since infant vaccination was recommended in 1996. In recent years, however, outbreaks have occurred among an increasingly susceptible adult population. Although HEV is the most common cause of acute viral hepatitis in developing countries, it is rarely diagnosed in the United States. Copyright © 2018 Cold Spring Harbor Laboratory Press; all rights reserved.
Full Text Available The current Ebola virus outbreak has highlighted the uncertainties surrounding many aspects of Ebola virus virology, including routes of transmission. The scientific community played a leading role during the outbreak-potentially, the largest of its kind-as many of the questions surrounding ebolaviruses have only been interrogated in the laboratory. Scientists provided an invaluable resource for clinicians, public health officials, policy makers, and the lay public in understanding the progress of Ebola virus disease and the continuing outbreak. Not all of the scientific communication, however, was accurate or effective. There were multiple instances of published articles during the height of the outbreak containing potentially misleading scientific language that spurred media overreaction and potentially jeopardized preparedness and policy decisions at critical points. Here, we use articles declaring the potential for airborne transmission of Ebola virus as a case study in the inaccurate reporting of basic science, and we provide recommendations for improving the communication about unknown aspects of disease during public health crises.
Kilianski, Andy; Evans, Nicholas G
The current Ebola virus outbreak has highlighted the uncertainties surrounding many aspects of Ebola virus virology, including routes of transmission. The scientific community played a leading role during the outbreak-potentially, the largest of its kind-as many of the questions surrounding ebolaviruses have only been interrogated in the laboratory. Scientists provided an invaluable resource for clinicians, public health officials, policy makers, and the lay public in understanding the progress of Ebola virus disease and the continuing outbreak. Not all of the scientific communication, however, was accurate or effective. There were multiple instances of published articles during the height of the outbreak containing potentially misleading scientific language that spurred media overreaction and potentially jeopardized preparedness and policy decisions at critical points. Here, we use articles declaring the potential for airborne transmission of Ebola virus as a case study in the inaccurate reporting of basic science, and we provide recommendations for improving the communication about unknown aspects of disease during public health crises.
Fauteux-Daniel, Sébastien; Larouche, Ariane; Calderon, Virginie; Boulais, Jonathan; Béland, Chanel; Ransy, Doris G; Boucher, Marc; Lamarre, Valérie; Lapointe, Normand; Boucoiran, Isabelle; Le Campion, Armelle; Soudeyns, Hugo
Hepatitis C virus (HCV) can be transmitted from mother to child during pregnancy and childbirth. However, the timing and precise biological mechanisms that are involved in this process are incompletely understood, as are the determinants that influence transmission of particular HCV variants. Here we report results of a longitudinal assessment of HCV quasispecies diversity and composition in 5 cases of vertical HCV transmission, including 3 women coinfected with human immunodeficiency virus type 1 (HIV-1). The population structure of HCV variant spectra based on E2 envelope gene sequences (nucleotide positions 1491 to 1787), including hypervariable regions 1 and 2, was characterized using next-generation sequencing and median-joining network analysis. Compatible with a loose transmission bottleneck, larger numbers of shared HCV variants were observed in the presence of maternal coinfection. Coalescent Bayesian Markov chain Monte Carlo simulations revealed median times of transmission between 24.9 weeks and 36.1 weeks of gestation, with some confidence intervals ranging into the 1st trimester, considerably earlier than previously thought. Using recombinant autologous HCV pseudoparticles, differences were uncovered in HCV-specific antibody responses between coinfected mothers and mothers infected with HCV alone, in whom generalized absence of neutralization was observed. Finally, shifts in HCV quasispecies composition were seen in children around 1 year of age, compatible with the disappearance of passively transferred maternal immunoglobulins and/or the development of HCV-specific humoral immunity. Taken together, these results provide insights into the timing, dynamics, and biologic mechanisms involved in vertical HCV transmission and inform preventative strategies. IMPORTANCE Although it is well established that hepatitis C virus (HCV) can be transmitted from mother to child, the manner and the moment at which transmission operates have been the subject of
O'Toole, B I; Burton, M J; Rothwell, A; Outram, S; Dadds, M; Catts, S V
To assess the association between parental post-traumatic stress disorder (PTSD) and offspring PTSD and its specificity for other disorders in a non-clinical epidemiological cohort of Australian Vietnam veterans, their partners and their sons and daughters. Veterans were interviewed twice, in 1992-1994 and 2005-2006; partners were interviewed in 2006-2007, and their offspring in 2012-2014. A total of 125 sons and 168 daughters were interviewed from 197 families, 137 of which also included partners who were the mothers of the children. Statistical analysis used multi-level modelling to compute odds ratios and 95% confidence intervals while controlling for clustering effects within families. Parent PTSD diagnoses were examined for associations with offspring trauma exposure, PTSD and other psychiatric diagnoses. Veteran PTSD increased the risk of PTSD and no other disorder in both sons and daughters; partner PTSD did not. Veteran depression was also a risk factor for sons' PTSD, and alcohol disorder was linked to alcohol dependence in sons and PTSD in daughters, but not when controlling for veteran PTSD. We conclude that PTSD in a Vietnam veteran father increases the risk specifically for PTSD in his sons and daughters. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Nguyen, Diep T; Bryant, Juliet E; Davis, C Todd; Nguyen, Long V; Pham, Long T; Loth, Leo; Inui, Ken; Nguyen, Tung; Jang, Yunho; To, Thanh L; Nguyen, Tho D; Hoang, Diep T; Do, Hoa T; Nguyen, Trang T; Newman, Scott; Jennifer Siembieda; Pham, Dong V
Active surveillance for avian influenza (Al) viruses in poultry sold at live bird markets (LBMs) was conducted in 44 of 63 provinces throughout Vietnam over two periods from September 2011 to February 2012 and October 2012 to June 2013. The study objectives were to assess the prevalence of avian influenza type A, H5, and H5N1 subtype viruses and characterize the geographical and temporal distribution of H5N1 virus genetic variants across the country. Monthly sampling was conducted in 394 LBMs located in 372 communes. A total of 9790 oropharyngeal swabs from poultry were screened for influenza A virus by real-time reverse-transcriptase PCR Virus isolation was attempted on all positive samples in embryonated chicken eggs, and the HA1 region of each H5 virus isolate was sequenced. Market prevalence of H5 subtype virus was 32.2% (127/394) over the cumulative 15 mo of surveillance. Phylogenetic analyses indicated that clade 1.1 viruses persisted in the south, whereas three genetically distinct subgroups of dade 188.8.131.52 were found simultaneously in northern, central, and southern Vietnam. Clade 184.108.40.206c viruses first appeared in July 2012 and spread rapidly to the center and south of Vietnam in late 2012, where they were predominant among clade 220.127.116.11 viruses and were detected in both active LBM surveillance and poultry outbreaks. Given the overlapping geographic distribution of dade variants and the antigenic divergence previously described for these dades, current AI poultry vaccines used in Vietnam may require bivalent formulations containing representatives of both dade 1.1 and dade 18.104.22.168 viruses.
Insects are critical for the spread of most plant virus diseases, with >75% of plant viruses depending on an insects for transmission to new, uninfected hosts. However, little is known about the molecular and cellular factors in the insect that are important for virus transmission. The black-faced l...
Ciota, Alexander T; Bialosuknia, Sean M; Ehrbar, Dylan J; Kramer, Laura D
To determine the potential role of vertical transmission in Zika virus expansion, we evaluated larval pools of perorally infected Aedes aegypti and Ae. albopictus adult female mosquitoes; ≈1/84 larvae tested were Zika virus-positive; and rates varied among mosquito populations. Thus, vertical transmission may play a role in Zika virus spread and maintenance.
During the process of circulative plant virus transmission by insect vectors, viruses interact with different insect vector tissues prior to transmission to a new host plant. An area of intense debate in the field is whether bacterial symbionts of insect vectors are involved in the virus transmissi...
Defendorf, Charles M; Paul, Sindy; Scott, George J
Hepatitis C virus (HCV) infection poses significant adverse health effects. Improper use of vials, needles, syringes, intravenous bags, tubing, and connectors for injections and infusions is a current preventable cause of iatrogenic HCV transmission. Numerous cases have demonstrated the need for continued vigilance and the widespread nature of this iatrogenic infection risk across a variety of medical practice settings in the United States. Failure to implement the evidence-based Centers for Disease Control and Prevention (CDC) infection prevention guidelines exposes patients to preventable harm. The guidelines establish the requirement to notify patients in cases of suspected virus transmission, as well as to screen those patients who would not otherwise have been at risk for HCV seroconversion and other bloodborne pathogens. Legal and regulatory ramifications, including state, criminal, and tort laws, hold physicians and other health care professionals accountable to use safe injection practices. This article reviews the major health risks of HCV infection, significant effects of iatrogenic infection transmission, CDC guidelines for safe injection practices, and legal regulations and ramifications designed to promote safe injection practices.
...-2011-0011] Public Health Service Guideline for Reducing Transmission of Human Immunodeficiency Virus... public comment on the draft Public Health Service Guideline for Reducing Transmission of Human..., Attn: Public Health Service Guideline for Reducing Transmission of Human Immunodeficiency Virus (HIV...
Bawo, Luke; Fallah, Mosoka; Kateh, Francis; Nagbe, Thomas; Clement, Peter; Gasasira, Alex; Mahmoud, Nuha; Musa, Emmanuel; Lo, Terrence Q; Pillai, Satish K; Seeman, Sara; Sunshine, Brittany J; Weidle, Paul J; Nyensweh, Tolbert
Following 42 days since the last Ebola virus disease (Ebola) patient was discharged from a Liberian Ebola treatment unit (ETU), September 3, 2015, marks the second time in a 4-month period that the World Health Organization (WHO) has declared Liberia free of Ebola virus transmission (1). The first confirmed Ebola cases in West Africa were identified in southeastern Guinea on March 23, 2014, and within 1 week, cases were identified and confirmed in Liberia (1). Since then, Liberia has reported 5,036 confirmed and probable Ebola cases and 4,808 Ebola-related deaths. The epidemic in Liberia peaked in late summer and early fall of 2014, when more than 200 confirmed and probable cases were reported each week .
Meyer, A; Dinh, T X; Han, T A; Do, D V; Nhu, T V; Pham, L T; Nguyen, T T T; Newman, S; Häsler, B; Pfeiffer, D U; Vergne, T
Highly pathogenic avian influenza (HPAI) viruses continue to threaten smallholder poultry producers in several South-east Asian countries, including Vietnam. In particular, the free-grazing duck system has been repeatedly highlighted as a major risk factor for HPAI outbreaks. Free-grazing ducks, which scavenge on rice paddies after the harvest, account for a large proportion of the duck population in Vietnam and the wider South-east Asian region. However, the structure and dynamics of the free-grazing duck production from farm to consumption has not been described for Vietnam. In this study, we used a value chain approach to provide a complete picture of the actors involved in the production and marketing of free-grazing duck eggs and spent layer ducks, as well as to investigate the governance structure of this food system. Group interviews and key informant interviews were conducted in two provinces located in the Mekong River Delta (MRD) and the Red River Delta (RRD). The results presented here highlight similarities and differences in farming and trade practices between the two provinces. The trade of spent layer ducks involved large volumes of live ducks being sent to China and Cambodia for consumption, generating a substantial risk of transboundary spread of pathogens, including HPAI viruses. We describe the major role of "duck yards", which act as hubs in the northbound trade of spent layer ducks. These yards should be considered as essential links in the value chain of spent layer ducks when considering HPAI surveillance and control. The veterinary authorities are only marginally involved in the value chain activities, and their influence could be strengthened by increasing surveillance activities for instance in duck yards. Last, we discuss the dynamics of the duck value chain and further implications for future HPAI management policies. © 2017 The Authors. Transboundary and Emerging Diseases Published by Blackwell Verlag GmbH.
de Carvalho Ferreira, H C; Pauszek, S J; Ludi, A; Huston, C L; Pacheco, J M; Le, V T; Nguyen, P T; Bui, H H; Nguyen, T D; Nguyen, T; Nguyen, T T; Ngo, L T; Do, D H; Rodriguez, L; Arzt, J
Foot-and-mouth disease (FMD) is a major constraint to transboundary trade in animal products, yet much of its natural ecology and epidemiology in endemic regions is still poorly understood. To address this gap, a multidisciplinary, molecular and conventional epidemiological approach was applied to an investigation of endemic FMD in Vietnam. Within the study space, it was found that 22.3% of sampled ruminants had previously been infected with FMD virus (FMDV), of which 10.8% were persistent, asymptomatic carriers (2.4% of the total population). Descriptive data collected from targeted surveillance and a farm questionnaire showed a significantly lower prevalence of FMDV infection for dairy farms. In contrast, farms of intermediate size and/or history of infection in 2010 were at increased risk of FMD exposure. At the individual animal level, buffalo had the highest exposure risk (over cattle), and there was spatial heterogeneity in exposure risk at the commune level. Conversely, carrier prevalence was higher for beef cattle, suggesting lower susceptibility of buffalo to persistent FMDV infection. To characterize virus strains currently circulating in Vietnam, partial FMDV genomic (VP1) sequences from carrier animals collected between 2012 and 2013 (N = 27) and from FMDV outbreaks between 2009 and 2013 (N = 79) were compared by phylogenetic analysis. Sequence analysis suggested that within the study period, there were two apparent novel introductions of serotype A viruses and that the dominant lineage of serotype O in Vietnam shifted from SEA/Mya-98 to ME-SA/PanAsia. FMDV strains shared close ancestors with FMDV from other South-East Asian countries indicating substantial transboundary movement of the predominant circulating strains. Close genetic relationships were observed between carrier and outbreak viruses, which may suggest that asymptomatic carriers of FMDV contribute to regional disease persistence. Multiple viral sequences obtained from carrier cattle
Heitmann, Anna; Jansen, Stephanie; Lühken, Renke; Leggewie, Mayke; Badusche, Marlis; Pluskota, Björn; Becker, Norbert; Vapalahti, Olli; Schmidt-Chanasit, Jonas; Tannich, Egbert
Mosquitoes collected in Germany in 2016, including Culex pipiens pipiens biotype pipiens, Culex torrentium and Aedes albopictus, as well as Culex pipiens pipiens biotype molestus (in colony since 2011) were experimentally infected with Zika virus (ZIKV) at 18 °C or 27 °C. None of the Culex taxa showed vector competence for ZIKV. In contrast, Aedes albopictus were susceptible for ZIKV but only at 27 °C, with transmission rates similar to an Aedes aegypti laboratory colony tested in parallel. This article is copyright of The Authors, 2017.
Full Text Available According to Chinese Guideline of Prevention and Treatment for Chronic Hepatitis B which is published in October, 2015, hepatitis B virus (HBV is mainly transmitted via injection, vertical transmission, and sexual contact, furthermore, invasive procedures including pedicure and tattooing as well as sharing shavers and toothbrushes are also regarded as risk factors. These traditional HBV transmission pathways are in accordance with the corresponding WHO guideline. However, some of the statements in the guidelines such as close contact with active HBV carriers like sharing hygiene facilities and dining together as well as bites by blood-sucking arthropod like mosquito do not transmit HBV need to be questioned because related previous studies did not support these statements.
Foppa Ivo M
Full Text Available Abstract Background Since its 1999 emergence in New York City, West Nile virus (WNV has become the most important and widespread cause of mosquito-transmitted disease in North America. Its sweeping spread from the Atlantic to the Pacific coast was accompanied by widespread mortality among wild birds, especially corvids. Only sporadic avian mortality had previously been associated with this infection in the Old World. Here, we examine the possibility that reservoir host mortality may intensify transmission, both by concentrating vector mosquitoes on remaining hosts and by preventing the accumulation of "herd immunity". Results Inspection of the Ross-Macdonald expression of the basic reproductive number (R0 suggests that this quantity may increase with reservoir host mortality. Computer simulation confirms this finding and indicates that the level of virulence is positively associated with the numbers of infectious mosquitoes by the end of the epizootic. The presence of reservoir incompetent hosts in even moderate numbers largely eliminated the transmission-enhancing effect of host mortality. Local host die-off may prevent mosquitoes to "waste" infectious blood meals on immune host and may thus facilitate perpetuation and spread of transmission. Conclusion Under certain conditions, host mortality may enhance transmission of WNV and similarly maintained arboviruses and thus facilitate their emergence and spread. The validity of the assumptions upon which this argument is built need to be empirically examined.
Muhammad Altaf Khan
Full Text Available Hepatitis B is a globally infectious disease. Mathematical modeling of HBV transmission is an interesting research area. In this paper, we present characteristics of HBV virus transmission in the form of a mathematical model. We analyzed the effect of immigrants in the model to study the effect of immigrants for the host population. We added the following flow parameters: “the transmission between migrated and exposed class” and “the transmission between migrated and acute class.” With these new features, we obtained a compartment model of six differential equations. First, we find the basic threshold quantity Ro and then find the local asymptotic stability of disease-free equilibrium and endemic equilibrium. Furthermore, we find the global stability of the disease-free and endemic equilibria. Previous similar publications have not added the kind of information about the numerical results of the model. In our case, from numerical simulation, a detailed discussion of the parameters and their numerical results is presented. We claim that with these assumptions and by adding the migrated class, the model informs policy for governments, to be aware of the immigrants and subject them to tests about the disease status. Immigrants for short visits and students should be subjected to tests to reduce the number of immigrants with disease.
Frise, Rebecca; Bradley, Konrad; van Doremalen, Neeltje; Galiano, Monica; Elderfield, Ruth A.; Stilwell, Peter; Ashcroft, Jonathan W.; Fernandez-Alonso, Mirian; Miah, Shahjahan; Lackenby, Angie; Roberts, Kim L.; Donnelly, Christl A.; Barclay, Wendy S.
Influenza viruses cause annual seasonal epidemics and occasional pandemics. It is important to elucidate the stringency of bottlenecks during transmission to shed light on mechanisms that underlie the evolution and propagation of antigenic drift, host range switching or drug resistance. The virus spreads between people by different routes, including through the air in droplets and aerosols, and by direct contact. By housing ferrets under different conditions, it is possible to mimic various routes of transmission. Here, we inoculated donor animals with a mixture of two viruses whose genomes differed by one or two reverse engineered synonymous mutations, and measured the transmission of the mixture to exposed sentinel animals. Transmission through the air imposed a tight bottleneck since most recipient animals became infected by only one virus. In contrast, a direct contact transmission chain propagated a mixture of viruses suggesting the dose transferred by this route was higher. From animals with a mixed infection of viruses that were resistant and sensitive to the antiviral drug oseltamivir, resistance was propagated through contact transmission but not by air. These data imply that transmission events with a looser bottleneck can propagate minority variants and may be an important route for influenza evolution. PMID:27430528
Lukashov, V. V.; Goudsmit, J.
We and others have shown that in individual human immunodeficiency virus type 1 (HIV-1) infection, the adaptive evolution of HIV-1 is influenced by host immune competence. In this study, we tested the hypothesis that in addition to selective forces operating within the host, transmission bottlenecks
Blitvich, Bradley J
West Nile virus (WNV) is a flavivirus that is maintained in a bird-mosquito transmission cycle. Humans, horses and other non-avian vertebrates are usually incidental hosts, but evidence is accumulating that this might not always be the case. Historically, WNV has been associated with asymptomatic infections and sporadic disease outbreaks in humans and horses in Africa, Europe, Asia and Australia. However, since 1994, the virus has caused frequent outbreaks of severe neuroinvasive disease in humans and horses in Europe and the Mediterranean Basin. In 1999, WNV underwent a dramatic expansion of its geographic range, and was reported for the first time in the Western Hemisphere during an outbreak of human and equine encephalitis in New York City. The outbreak was accompanied by extensive and unprecedented avian mortality. Since then, WNV has dispersed across the Western Hemisphere and is now found throughout the USA, Canada, Mexico and the Caribbean, and parts of Central and South America. WNV has been responsible for >27,000 human cases, >25,000 equine cases and hundreds of thousands of avian deaths in the USA but, surprisingly, there have been only sparse reports of WNV disease in vertebrates in the Caribbean and Latin America. This review summarizes our current understanding of WNV with particular emphasis on its transmission dynamics and changing epidemiology.
Full Text Available Zika virus (ZIKV has emerged as a new global health threat. Since its first discovery in Zika forest in Uganda, this virus has been isolated from several mosquito species, including Aedes aegypti and Aedes albopictus. The geographical distribution of these mosquito species across tropical and subtropical regions has led to several outbreaks, including the recent pandemic in Brazil, followed by the Pacific islands and other areas of North and South America. This has gained attention of the scientific community to elucidate the epidemiology and transmission of ZIKV. Despite its strong attention on clinical aspects for healthcare professionals, the relationships between ZIKV and its principal vectors, A. aegypti and A. albopictus, have not gained substantial interest in the scientific research community. As such, this review aims to summarize the current knowledge on ZIKV tropism and some important mechanisms which may be employed by the virus for effective strategies on viral survival in mosquitoes. In addition, this review identifies the areas of research that should be placed attention to, for which to be exploited for novel mosquito control strategies.
Tham, Hong-Wai; Balasubramaniam, Vinod; Ooi, Man K.; Chew, Miaw-Fang
Zika virus (ZIKV) has emerged as a new global health threat. Since its first discovery in Zika forest in Uganda, this virus has been isolated from several mosquito species, including Aedes aegypti and Aedes albopictus. The geographical distribution of these mosquito species across tropical and subtropical regions has led to several outbreaks, including the recent pandemic in Brazil, followed by the Pacific islands and other areas of North and South America. This has gained attention of the scientific community to elucidate the epidemiology and transmission of ZIKV. Despite its strong attention on clinical aspects for healthcare professionals, the relationships between ZIKV and its principal vectors, A. aegypti and A. albopictus, have not gained substantial interest in the scientific research community. As such, this review aims to summarize the current knowledge on ZIKV tropism and some important mechanisms which may be employed by the virus for effective strategies on viral survival in mosquitoes. In addition, this review identifies the areas of research that should be placed attention to, for which to be exploited for novel mosquito control strategies. PMID:29875751
Xia, Zhi-Qiang; Wang, Shi-Fu; Li, Shen-Long; Huang, Liu-Yu; Zhang, Wen-Yi; Sun, Gui-Quan; Gai, Zhong-Tao; Jin, Zhen
Ebola virus disease (EVD) has erupted many times in some zones since it was first found in 1976. The 2014 EVD outbreak in West Africa is the largest ever, which has caused a large number of deaths and the most serious country is Liberia during the outbreak period. Based on the data released by World Health Organization and the actual transmission situations, we investigate the impact of different transmission routes on the EVD outbreak in Liberia and estimate the basic reproduction number R0 = 2.012 in the absence of effective control measures. Through sensitivity and uncertainty analysis, we reveal that the transmission coefficients of suspected and probable cases have stronger correlations on the basic reproduction number. Furthermore, we study the influence of control measures (isolation and safe burial measures) on EVD outbreak. It is found that if combined control measures are taken, the basic reproduction number will be less than one and thus EVD in Liberia may be well contained. The obtained results may provide new guidance to prevent and control the spread of disease.
Full Text Available Carefully calibrated transmission models have the potential to guide public health officials on the nature and scale of the interventions required to control epidemics. In the context of the ongoing Ebola virus disease (EVD epidemic in Liberia, Drake and colleagues, in this issue of PLOS Biology, employed an elegant modeling approach to capture the distributions of the number of secondary cases that arise in the community and health care settings in the context of changing population behaviors and increasing hospital capacity. Their findings underscore the role of increasing the rate of safe burials and the fractions of infectious individuals who seek hospitalization together with hospital capacity to achieve epidemic control. However, further modeling efforts of EVD transmission and control in West Africa should utilize the spatial-temporal patterns of spread in the region by incorporating spatial heterogeneity in the transmission process. Detailed datasets are urgently needed to characterize temporal changes in population behaviors, contact networks at different spatial scales, population mobility patterns, adherence to infection control measures in hospital settings, and hospitalization and reporting rates.
Full Text Available Korean ginseng (Panax ginseng is the most popular herb for medical purpose in Korea. Recently, viral diseases from Korean ginseng showing various degrees of severe mottling, variegation and mosaic symptoms have caused quantity losses of Korean ginseng in a large number of farms. Watermelon mosaic virus (named WMVgin was identified as a causal agent for the disease of Korean ginseng. Interestingly, WMV-gin failed to infect both Korean ginseng plant and susceptible host species including cucurbitaceous plants by mechanical inoculation. However, WMV-gin could successfully infect Korean ginseng by transmission of two aphid species (Myzus persicae and Aphis gossypii. It is likely that transmission of WMV-gin was done by both the aphid species during feeding behavior of the two aphid species on Korean ginseng, though the aphids dislike feeding in Korea ginseng. Similarly, a strain of WMV (WMV-wm isolated from watermelon was transmitted successfully to Korean ginseng plant by the two aphid species, but not by mechanical inoculations. Transmission assays using M. persicae and A. gossypii clearly showed both WMV-gin and WMV-wm were not transmitted from infected Korean ginseng plant to cucurbit species that are good host species for WMV. These results suggest WMV disease occurring in Korean ginseng plant can be controlled by ecological approaches.
Full Text Available Non-self recognition is a common phenomenon among organisms; it often leads to innate immunity to prevent the invasion of parasites and maintain the genetic polymorphism of organisms. Fungal vegetative incompatibility is a type of non-self recognition which often induces programmed cell death (PCD and restricts the spread of molecular parasites. It is not clearly known whether virus infection could attenuate non-self recognition among host individuals to facilitate its spread. Here, we report that a hypovirulence-associated mycoreovirus, named Sclerotinia sclerotiorum mycoreovirus 4 (SsMYRV4, could suppress host non-self recognition and facilitate horizontal transmission of heterologous viruses. We found that cell death in intermingled colony regions between SsMYRV4-infected Sclerotinia sclerotiorum strain and other tested vegetatively incompatible strains was markedly reduced and inhibition barrage lines were not clearly observed. Vegetative incompatibility, which involves Heterotrimeric guanine nucleotide-binding proteins (G proteins signaling pathway, is controlled by specific loci termed het (heterokaryon incompatibility loci. Reactive oxygen species (ROS plays a key role in vegetative incompatibility-mediated PCD. The expression of G protein subunit genes, het genes, and ROS-related genes were significantly down-regulated, and cellular production of ROS was suppressed in the presence of SsMYRV4. Furthermore, SsMYRV4-infected strain could easily accept other viruses through hyphal contact and these viruses could be efficiently transmitted from SsMYRV4-infected strain to other vegetatively incompatible individuals. Thus, we concluded that SsMYRV4 is capable of suppressing host non-self recognition and facilitating heterologous viruses transmission among host individuals. These findings may enhance our understanding of virus ecology, and provide a potential strategy to utilize hypovirulence-associated mycoviruses to control fungal diseases.
Full Text Available H9N2 avian influenza A viruses are endemic in poultry of many Eurasian countries and have caused repeated human infections in Asia since 1998. To evaluate the potential threat of H9N2 viruses to humans, we investigated the replication and transmission efficiency of H9N2 viruses in the ferret model. Five wild-type (WT H9N2 viruses, isolated from different avian species from 1988 through 2003, were tested in vivo and found to replicate in ferrets. However these viruses achieved mild peak viral titers in nasal washes when compared to those observed with a human H3N2 virus. Two of these H9N2 viruses transmitted to direct contact ferrets, however no aerosol transmission was detected in the virus displaying the most efficient direct contact transmission. A leucine (Leu residue at amino acid position 226 in the hemagglutinin (HA receptor-binding site (RBS, responsible for human virus-like receptor specificity, was found to be important for the transmission of the H9N2 viruses in ferrets. In addition, an H9N2 avian-human reassortant virus, which contains the surface glycoprotein genes from an H9N2 virus and the six internal genes of a human H3N2 virus, showed enhanced replication and efficient transmission to direct contacts. Although no aerosol transmission was observed, the virus replicated in multiple respiratory tissues and induced clinical signs similar to those observed with the parental human H3N2 virus. Our results suggest that the establishment and prevalence of H9N2 viruses in poultry pose a significant threat for humans.
Chen, Shuilian; Zhang, Heng; Luo, Meiling; Chen, Jingfang; Yao, Dong; Chen, Faming; Liu, Ruchun; Chen, Tianmu
We report rabies virus transmission among solid organ transplantation recipients in Changsha, China, in 2016. Two recipients were confirmed to have rabies and died. Our findings suggest that more attention should be paid to the possibility of rabies virus transmission through organ transplantation for clinical and public health reasons.
Colenutt, C.; Gonzales, J.L.; Paton, D.J.; Gloster, J.; Nelson, N.; Sanders, C.
Foot-and-mouth disease virus (FMDV) control measures rely on understanding of virus transmission mechanisms. Direct contact between naïve and infected animals or spread by contaminated fomites is prevented by quarantines and rigorous decontamination procedures during outbreaks. Transmission of
Phung, Thi Bich Thuy; Alestig, Erik; Nguyen, Thanh Liem; Hannoun, Charles; Lindh, Magnus
There are eight known genotypes of hepatitis B virus, A-H, and several subgenotypes, with rather well-defined geographic distributions. HBV genotypes were evaluated in 153 serum samples from Hanoi, Vietnam. Of the 87 samples that could be genotyped, genotype B was found in 67 (77%) and genotype C in 19 (22%). All genotype C strains were of subgenotype C1, and the majority of genotype B strains were B4, while a few were B2. The genotype X/C recombinant strain, identified previously in Swedish patients of indigenous Vietnamese origin, was found in one sample. This variant, proposed to be classified as genotype I, has been found recently also by others in Vietnam and Laos. The current study indicates that the genotype X/C recombinant may represent approximately 1% of the HBV strains circulating in Vietnam. (c) 2010 Wiley-Liss, Inc.
Lauer, J L; VanDrunen, N A; Washburn, J W; Balfour, H H
The transmission of hepatitis B virus (HBV) in clinical laboratory areas was delineated by the use of hepatitis B surface antigen (HBsAg) as presumptive evidence for the presence of the infective agent. Twenty-six (34%) of 76 environmental surfaces sampled were positive for HBsAg. The outer surfaces of blood- and serum-specimen containers had HBsAg contamination rates of 55% (six of 11) and 44% (four of nine), respectively. Subsequent handling of pipetting aids, marking devices, and other items led to their contamination and further dissemination of HBsAg. An assay instrument for complete determinations of blood cell counts was observed to splatter and drip blood during its operation. The contamination rate for environmental surfaces associated with this instrument was 15%. The data indicate that transmission of HBV in the clinical laboratory is subtle and mainly via hand contact with contaminated items during the various steps of blood processing. These data support the concept that the portal of entry of HBV is through inapparent breaks in skin and mucous membranes.
Seibert, Christopher W.; Rahmat, Saad; Krause, Jens C.; Eggink, Dirk; Albrecht, Randy A.; Goff, Peter H.; Krammer, Florian; Duty, J. Andrew; Bouvier, Nicole M.; García-Sastre, Adolfo
A serum hemagglutination inhibition (HAI) titer of 40 or greater is thought to be associated with reduced influenza virus pathogenesis in humans and is often used as a correlate of protection in influenza vaccine studies. We have previously demonstrated that intramuscular vaccination of guinea pigs with inactivated influenza virus generates HAI titers greater than 300 but does not protect vaccinated animals from becoming infected with influenza virus by transmission from an infected cage mate. Only guinea pigs intranasally inoculated with a live influenza virus or a live attenuated virus vaccine, prior to challenge, were protected from transmission (A. C. Lowen et al., J. Virol. 83:2803–2818, 2009.). Because the serum HAI titer is mostly determined by IgG content, these results led us to speculate that prevention of viral transmission may require IgA antibodies or cellular immune responses. To evaluate this hypothesis, guinea pigs and ferrets were administered a potent, neutralizing mouse IgG monoclonal antibody, 30D1 (Ms 30D1 IgG), against the A/California/04/2009 (H1N1) virus hemagglutinin and exposed to respiratory droplets from animals infected with this virus. Even though HAI titers were greater than 160 1 day postadministration, Ms 30D1 IgG did not prevent airborne transmission to passively immunized recipient animals. In contrast, intramuscular administration of recombinant 30D1 IgA (Ms 30D1 IgA) prevented transmission to 88% of recipient guinea pigs, and Ms 30D1 IgA was detected in animal nasal washes. Ms 30D1 IgG administered intranasally also prevented transmission, suggesting the importance of mucosal immunity in preventing influenza virus transmission. Collectively, our data indicate that IgG antibodies may prevent pathogenesis associated with influenza virus infection but do not protect from virus infection by airborne transmission, while IgA antibodies are more important for preventing transmission of influenza viruses. PMID:23698296
Richard, Mathilde; Fouchier, Ron A.M.
Many respiratory viruses of humans originate from animals. For instance, there are now eight paramyxoviruses, four coronaviruses and four orthomxoviruses that cause recurrent epidemics in humans but were once confined to other hosts. In the last decade, several members of the same virus families have jumped the species barrier from animals to humans. Fortunately, these viruses have not become established in humans, because they lacked the ability of sustained transmission between humans. However, these outbreaks highlighted the lack of understanding of what makes a virus transmissible. In part triggered by the relatively high frequency of occurrence of influenza A virus zoonoses and pandemics, the influenza research community has started to investigate the viral genetic and biological traits that drive virus transmission via aerosols or respiratory droplets between mammals. Here we summarize recent discoveries on the genetic and phenotypic traits required for airborne transmission of zoonotic influenza viruses of subtypes H5, H7 and H9 and pandemic viruses of subtypes H1, H2 and H3. Increased understanding of the determinants and mechanisms of respiratory virus transmission is not only key from a basic scientific perspective, but may also aid in assessing the risks posed by zoonotic viruses to human health, and preparedness for such risks. PMID:26385895
Full Text Available West Nile virus (WNV and Rift Valley fever virus (RVFV are two emerging arboviruses transmitted by Culex pipiens species that includes two biotypes: pipiens and molestus. In Lebanon, human cases caused by WNV and RVFV have never been reported. However, the introduction of these viruses in the country is likely to occur through the migratory birds and animal trades. In this study, we evaluated the ability of Cx. pipiens, a predominant mosquito species in urban and rural regions in Lebanon, to transmit WNV and RVFV. Culex egg rafts were collected in the West Bekaa district, east of Lebanon and adult females of Cx. pipiens were experimentally infected with WNV and RVFV Clone 13 strain at titers of 1.6×108 and 1.33×107 plaque forming units (PFU/mL, respectively. We estimated viral infection, dissemination and transmission at 3, 7, 14 and 19 days post infection (dpi. Results showed that infection was higher for WNV than for RVFV from 3 dpi to 19 dpi. Viral dissemination and transmission started from 3 dpi for WNV; and only from 19 dpi for RVFV. Moreover, Cx. pipiens were able to excrete in saliva a higher number of viral particles of WNV (1028 ± 405 PFU/saliva at 19 dpi than RVFV (42 PFU/saliva at 19 dpi. Cx. pipiens from Lebanon are efficient experimental vectors of WNV and to a lower extent, RVFV. These findings should stimulate local authorities to establish an active entomological surveillance in addition to animal surveys for both viruses in the country.
Peters, Lars; Weis, Nina M; Lindhardt, Bjarne Orskov
Infections with the hepatitis C virus (HCV) occur primarily through percutaneous transmission, while sexual transmission seems to be rare. Recently, in some European cities, an increasing incidence of sexually transmitted HCV infection among HIV-infected homosexual males has been reported. We...... describe four cases of acute HCV infection among HIV-infected homosexual males, where sexual transmission was likely. Udgivelsesdato: 2006-Oct-16...
Bravo De Rueda, C.; Jong, de M.C.M.; Eble, P.L.; Dekker, A.
The quantitative role of sheep in the transmission of foot-and-mouth disease virus (FMDV) is not well known. To estimate the role of sheep in the transmission of FMDV, a direct contact transmission experiment with 10 groups of animals each consisting of 2 infected lambs and 1 contact calf was
Levitt, Abby L; Singh, Rajwinder; Cox-Foster, Diana L; Rajotte, Edwin; Hoover, Kelli; Ostiguy, Nancy; Holmes, Edward C
There are a number of RNA virus pathogens that represent a serious threat to the health of managed honey bees (Apis mellifera). That some of these viruses are also found in the broader pollinator community suggests the wider environmental spread of these viruses, with the potential for a broader impact on ecosystems. Studies on the ecology and evolution of these viruses in the arthropod community as a whole may therefore provide important insights into these potential impacts. We examined managed A. mellifera colonies, nearby non-Apis hymenopteran pollinators, and other associated arthropods for the presence of five commonly occurring picorna-like RNA viruses of honey bees - black queen cell virus, deformed wing virus, Israeli acute paralysis virus, Kashmir bee virus and sacbrood virus. Notably, we observed their presence in several arthropod species. Additionally, detection of negative-strand RNA using strand-specific RT-PCR assays for deformed wing virus and Israeli acute paralysis virus suggests active replication of deformed wing virus in at least six non-Apis species and active replication of Israeli acute paralysis virus in one non-Apis species. Phylogenetic analysis of deformed wing virus also revealed that this virus is freely disseminating across the species sampled in this study. In sum, our study indicates that these viruses are not specific to the pollinator community and that other arthropod species have the potential to be involved in disease transmission in pollinator populations. Copyright © 2013 Elsevier B.V. All rights reserved.
H. E. Simmons; Holly Prendeville; J. P. Dunham; M. J. Ferrari; J. D. Earnest; D. Pilson; G. P. Munkvold; E. C. Holmes; A. G. Stephenson
Zucchini yellow mosaic virus (ZYMV) is an economically important pathogen of cucurbits that is transmitted both horizontally and vertically. Although ZYMV is seed-transmitted in Cucurbita pepo, the potential for seed transmission in virus-resistant transgenic cultivars is not known. We crossed and backcrossed a transgenic...
Do, Vinh Thi; Ho, Hien Thi; Nguyen, Tri Manh; Do, Huynh Khac
We conducted a cross-sectional study among 148 women who were regular sexual partners of male injecting drug users in Tien Du, Bac Ninh province, Vietnam to identify the rate of HIV infection and factors associated with HIV transmission among them. HIV infection rate among sexual partners was high, 11.5%. Sexual violence was prevalent, 63.5% among sexual partners; 94.1% (16/17) among those with HIV. We discovered an association between sexual violence and HIV infection. Sexual partners suffering from sexual violence caused by their regular sexual partners faced 9.24 times higher HIV risk than those who did not have sexual violence.
Full Text Available Hepatitis C virus (HCV is a genetically diverse pathogen infecting approximately 2-3% of the world's population. Herein, we describe results of a large, multicentre serological and molecular epidemiological study cataloguing the prevalence and genetic diversity of HCV in five regions of Vietnam; Ha Noi, Hai Phong, Da Nang, Khanh Hoa and Can Tho. Individuals (n=8654 with varying risk factors for infection were analysed for the presence of HCV Ab/Ag and, in a subset of positive specimens, for HCV RNA levels (n=475 and genotype (n=282. In lower risk individuals, including voluntary blood donors, military recruits and pregnant women, the prevalence of infection was 0.5% (n=26/5250. Prevalence rates were significantly higher (p<0.001 in intravenous drug users (IDUs; 55.6%, n=556/1000, dialysis patients (26.6%, n=153/575 commercial sex workers (CSWs; 8.7%, n=87/1000, and recipients of multiple blood transfusions (6.0%, n=32/529. The prevalence of HCV in dialysis patients varied but remained high in all regions (11-43% and was associated with the receipt of blood transfusions [OR: 2.08 (1.85-2.34, p=0.001], time from first transfusion [OR: 1.07 (1.01-1.13, p=0.023], duration of dialysis [OR: 1.31 (1.19-1.43, p<0.001] and male gender [OR: 1.60 (1.06-2.41, p=0.026]. Phylogenetic analysis revealed high genetic diversity, particularly amongst dialysis and multi-transfused patients, identifying subtypes 1a (33%, 1b (27%, 2a (0.4%, 3a (0.7%, 3b (1.1%, 6a (18.8%, 6e (6.0%, 6h (4.6%, 6l (6.4% and 2 clusters of novel genotype 6 variants (2.1%. HCV genotype 1 predominated in Vietnam (60%, n=169/282 but the proportion of infections attributable to genotype 1 varied between regions and risk groups and, in the Southern part of Vietnam, genotype 6 viruses dominated in dialysis and multi-transfused patients (73.9%. This study confirms a high prevalence of HCV infection in Vietnamese IDUs and, notably, reveals high levels of HCV infection associated with dialysis and
Uyeki, Timothy M.; Nguyen, Doan C.; Rowe, Thomas; Lu, Xiuhua; Hu-Primmer, Jean; Huynh, Lien P.; Hang, Nguyen L. K.; Katz, Jacqueline M.
BACKGROUND: The frequency of avian influenza A virus infections among poultry workers is not well understood. METHODS: A seroprevalence study of market poultry workers and persons without occupational poultry exposure was conducted during 2001 in Hanoi, Vietnam. Sera were tested for avian influenza H5 and H9 antibodies by microneutralization and Western blot assays. RESULTS: Seroprevalence of H5 and H9 antibodies was 4% and 3% in poultry workers and 1% and 3.5% in non-poultry workers, respect...
Van Nguyen, Dung; Van Nguyen, Cuong; Bonsall, David; Ngo, Tue Tri; Carrique-Mas, Juan; Pham, Anh Hong; Bryant, Juliet E; Thwaites, Guy; Baker, Stephen; Woolhouse, Mark; Simmonds, Peter
Rodents and bats are now widely recognised as important sources of zoonotic virus infections in other mammals, including humans. Numerous surveys have expanded our knowledge of diverse viruses in a range of rodent and bat species, including their origins, evolution, and range of hosts. In this study of pegivirus and human hepatitis-related viruses, liver and serum samples from Vietnamese rodents and bats were examined by PCR and sequencing. Nucleic acids homologous to human hepatitis B, C, E viruses were detected in liver samples of 2 (1.3%) of 157 bats, 38 (8.1%), and 14 (3%) of 470 rodents, respectively. Hepacivirus-like viruses were frequently detected (42.7%) in the bamboo rat, Rhizomys pruinosus , while pegivirus RNA was only evident in 2 (0.3%) of 638 rodent serum samples. Complete or near-complete genome sequences of HBV, HEV and pegivirus homologues closely resembled those previously reported from rodents and bats. However, complete coding region sequences of the rodent hepacivirus-like viruses substantially diverged from all of the currently classified variants and potentially represent a new species in the Hepacivirus genus. Of the viruses identified, their routes of transmission and potential to establish zoonoses remain to be determined.
Miranda-Saksena, Monica; Boadle, Ross; Cunningham, Anthony L
Transmission electron microscopy (TEM) provides the resolution necessary to identify both viruses and subcellular components of cells infected with many types of viruses, including herpes simplex virus. Recognized as a powerful tool in both diagnostic and research-based virology laboratories, TEM has made possible the identification of new viruses and has contributed to the elucidation of virus life cycle and virus-host cell interaction. Whilst there are many sample preparation techniques for TEM, conventional processing using chemical fixation and resin embedding remains a useful technique, available in virtually all EM laboratories, for studying virus/cell ultrastructure. In this chapter, we describe the preparation of herpes simplex virus-infected primary neurons, grown on plastic cover slips, to allow sectioning of neurons and axons in their growth plane. This technique allows TEM examination of cell bodies, axons, growth cones, and varicosities, providing powerful insights into virus-cell interaction.
Shen, Mingwang; Xiao, Yanni; Rong, Libin
Since the re-emergence of Ebola in West Africa in 2014, comprehensive and stringent interventions have been implemented to decelerate the spread of the disease. The effectiveness of interventions still remains unclear. In this paper, we develop an epidemiological model that includes various controlling measures to systematically evaluate their effects on the disease transmission dynamics. By fitting the model to reported cumulative cases and deaths in Guinea, Sierra Leone and Liberia until March 22, 2015, we estimate the basic reproduction number in these countries as 1.2552, 1.6093 and 1.7994, respectively. Model analysis shows that there exists a threshold of the effectiveness of isolation, below which increasing the fraction of latent individuals diagnosed prior to symptoms onset or shortening the duration between symptoms onset and isolation may lead to more Ebola infection. This challenges an existing view. Media coverage plays a substantial role in reducing the final epidemic size. The response to reported cumulative infected cases and deaths may have a different effect on the epidemic spread in different countries. Among all the interventions, we find that shortening the duration between death and burial and improving the effectiveness of isolation are two effective interventions for controlling the outbreak of Ebola virus infection.
Moosavy, Seyed Hamid; Davoodian, Parivash; Nazarnezhad, Mirza Ali; Nejatizaheh, Abdolazim; Eftekhar, Ebrahim; Mahboobi, Hamidreza
Hepatitis C infection is one of the main causes of chronic liver disorders worldwide. Nearly three percent (3%) of the world population has an HCV infection. Prevalence of HCV infection was higher in some groups such as injected drug users (IDUs) and HIV positive populations. Acute hepatitis has proven asymptomatic in most cases, and delay of diagnosis might lead to late onset of hepatocellular carcinoma and cirrhosis. Some host characteristics such as age, gender, body mass index, and viral properties are associated with HCV outcome hepatitis. Although disease progression is typically slow, some risk factors such as alcohol abuse and coinfection of patients with HBV and HIV can worsen the disease. On the other hand, viral overload is one of the main causes of prediction of HCV infection outcome. Prevalence of HCV infection will increase if we do not consider means of transmission, virus behaviors, and immunologic responses. Rapid diagnostic tests can help us to create preventive strategies among undeveloped villages and prisoners. Screening and training of the high-risk population such as IV drug users, dialysis patients, and hemophiliacs must be one of main HCV preventive programs. The present review is intended to help health policymakers to design suitable preventive and management programs.
Xiao, Fei; Fofana, Isabel; Heydmann, Laura
Hepatitis C virus (HCV) is transmitted between hepatocytes via classical cell entry but also uses direct cell-cell transfer to infect neighboring hepatocytes. Viral cell-cell transmission has been shown to play an important role in viral persistence allowing evasion from neutralizing antibodies....... In contrast, the role of HCV cell-cell transmission for antiviral resistance is unknown. Aiming to address this question we investigated the phenotype of HCV strains exhibiting resistance to direct-acting antivirals (DAAs) in state-of-the-art model systems for cell-cell transmission and spread. Using HCV...... genotype 2 as a model virus, we show that cell-cell transmission is the main route of viral spread of DAA-resistant HCV. Cell-cell transmission of DAA-resistant viruses results in viral persistence and thus hampers viral eradication. We also show that blocking cell-cell transmission using host...
Costa-Hurtado, Mar; Shepherd, Eric; DeJesus, Eric; Smith, Diane; Spackman, Erica; Kapczynski, Darrell R.; Suarez, David L.; Stallknecht, David E.; Swayne, David E.
ABSTRACT Wild aquatic birds have been associated with the intercontinental spread of H5 subtype highly pathogenic avian influenza (HPAI) viruses of the A/goose/Guangdong/1/96 (Gs/GD) lineage during 2005, 2010, and 2014, but dispersion by wild waterfowl has not been implicated with spread of other HPAI viruses. To better understand why Gs/GD H5 HPAI viruses infect and transmit more efficiently in waterfowl than other HPAI viruses, groups of mallard ducks were challenged with one of 14 different H5 and H7 HPAI viruses, including a Gs/GD lineage H5N1 (clade 2.2) virus from Mongolia, part of the 2005 dispersion, and the H5N8 and H5N2 index HPAI viruses (clade 22.214.171.124) from the United States, part of the 2014 dispersion. All virus-inoculated ducks and contact exposed ducks became infected and shed moderate to high titers of the viruses, with the exception that mallards were resistant to Ck/Pennsylvania/83 and Ck/Queretaro/95 H5N2 HPAI virus infection. Clinical signs were only observed in ducks challenged with the H5N1 2005 virus, which all died, and with the H5N8 and H5N2 2014 viruses, which had decreased weight gain and fever. These three viruses were also shed in higher titers by the ducks, which could facilitate virus transmission and spread. This study highlights the possible role of wild waterfowl in the spread of HPAI viruses. IMPORTANCE The spread of H5 subtype highly pathogenic avian influenza (HPAI) viruses of the Gs/GD lineage by migratory waterfowl is a serious concern for animal and public health. H5 and H7 HPAI viruses are considered to be adapted to gallinaceous species (chickens, turkeys, quail, etc.) and less likely to infect and transmit in wild ducks. In order to understand why this is different with certain Gs/GD lineage H5 HPAI viruses, we compared the pathogenicity and transmission of several H5 and H7 HPAI viruses from previous poultry outbreaks to Gs/GD lineage H5 viruses, including H5N1 (clade 2.2), H5N8 and H5N2 (clade 126.96.36.199) viruses, in
Cha, Ra Mi; Smith, Diane; Shepherd, Eric; Davis, C Todd; Donis, Ruben; Nguyen, Tung; Nguyen, Hoang Dang; Do, Hoa Thi; Inui, Ken; Suarez, David L; Swayne, David E; Pantin-Jackwood, Mary
Domestic ducks are the second most abundant poultry species in many Asian countries including Vietnam, and play a critical role in the epizootiology of H5N1 highly pathogenic avian influenza (HPAI) [FAO]. In this study, we examined the protective efficacy in ducks of two commercial H5N1 vaccines widely used in Vietnam; Re-1 containing A/goose/Guangdong/1/1996 hemagglutinin (HA) clade 0 antigens, and Re-5 containing A/duck/Anhui/1/2006 HA clade 2.3.4 antigens. Ducks received two doses of either vaccine at 7 and at 14 or 21 days of age followed by challenge at 30 days of age with viruses belonging to the HA clades 1.1, 188.8.131.52, 184.108.40.206.A and 220.127.116.11.B isolated between 2008 and 2011 in Vietnam. Ducks vaccinated with the Re-1 vaccine were protected after infection with the two H5N1 HPAI viruses isolated in 2008 (HA clades 1.1 and 18.104.22.168) showing no mortality and limited virus shedding. The Re-1 and Re-5 vaccines conferred 90-100% protection against mortality after challenge with the 2010 H5N1 HPAI viruses (HA clade 22.214.171.124.A); but vaccinated ducks shed virus for more than 7 days after challenge. Similarly, the Re-1 and Re-5 vaccines only showed partial protection against the 2011 H5N1 HPAI viruses (HA clade 126.96.36.199.A and 188.8.131.52.B), with a high proportion of vaccinated ducks shedding virus for more than 10 days. Furthermore, 50% mortality was observed in ducks vaccinated with Re-1 and challenged with the 184.108.40.206.B virus. The HA proteins of the 2011 challenge viruses had the greatest number of amino acid differences from the two vaccines as compared to the viruses from 2008 and 2009, which correlates with the lesser protection observed with these viruses. These studies demonstrate the suboptimal protection conferred by the Re-1 and Re-5 commercial vaccines in ducks against H5N1 HPAI clade 220.127.116.11 viruses, and underscore the importance of monitoring vaccine efficacy in the control of H5N1 HPAI in ducks. Published by Elsevier Ltd.
Li, Chunhua; Yuan, Manqiong; Lu, Ling; Lu, Teng; Xia, Wenjie; Pham, Van H; Vo, An X D; Nguyen, Mindie H; Abe, Kenji
Vietnam has a unique history in association with foreign countries, which may have resulted in multiple introductions of the alien HCV strains to mix with those indigenous ones. In this study, we characterized the HCV sequences in Core-E1 and NS5B regions from 236 Vietnamese individuals. We identified multiple HCV lineages; 6a, 6 e, 6h, 6k, 6l, 6 o, 6p, and two novel variants may represent the indigenous strains; 1a was probably introduced from the US; 1b and 2a possibly originated in East Asia; while 2i, 2j, and 2m were likely brought by French explorers. We inferred the evolutionary history for four major subtypes: 1a, 1b, 6a, and 6 e. The obtained Bayesian Skyline Plots (BSPs) consistently showed the rapid HCV population growth from 1955 to 1963 until 1984 or after, corresponding to the era of the Vietnam War. We also estimated HCV growth rates and reconstructed phylogeographic trees for comparing subtypes 1a, 1b, and HCV-2. Copyright © 2014 Elsevier Inc. All rights reserved.
Vu, Lan T H; Bui, Dieu
The burden of cervical cancer is increasing in Vietnam in the recent years, infection with high risk HPV being the cause. This study aimed to examine the prevalence of HPV and the distribution of HPV specific types among the general population in 5 big cities in Vietnam. Totals of 1500 women in round 1 and 3000 in round 2 were interviewed and underwent gynecological examination. HPV infection status, and HPV genotyping test were performed for all participants. Results indicated that the prevalence of HPV infection in 5 cities ranged from 6.1% to 10.2% with Can Tho having highest prevalence. The most common HPV types in all 5 cities were HPV 16, 18 and 58. Most of the positive cases were infected with high risk HPV, especially in Hanoi and Can Tho where more than 90% positive cases were high risk HPV. Furthermore, in Can Tho more than 60% of women were infected with multiple HPV types. The information from this study can be used to provide updated data for planning preventive activities for cervical cancer in the studied cities.
... in these fluids, but CDC and partners are working together to study how long the virus persists in ... Health, CDC, and the World Health Organization are working together to determine how long Ebola virus persists or ...
immune-electron microscopy (IEM) from patients' feces. They reported this virus particle as the causative agent of winter vomiting outbreaks in Norwalk (Kapikian et al.,. 1972). This is the remarkable landmark study of non- bacterial gastroenteritis viruses, especially for small round structured viruses (SRSVs). After that, many.
Takemae, Nobuhiro; Nguyen, Tung; Ngo, Long Thanh; Hiromoto, Yasuaki; Uchida, Yuko; Pham, Vu Phong; Kageyama, Tsutomu; Kasuo, Shizuko; Shimada, Shinichi; Yamashita, Yasutaka; Goto, Kaoru; Kubo, Hideyuki; Le, Vu Tri; Van Vo, Hung; Do, Hoa Thi; Nguyen, Dang Hoang; Hayashi, Tsuyoshi; Matsuu, Aya; Saito, Takehiko
The antigenicity of the influenza A virus hemagglutinin is responsible for vaccine efficacy in protecting pigs against swine influenza virus (SIV) infection. However, the antigenicity of SIV strains currently circulating in Japan and Vietnam has not been well characterized. We examined the antigenicity of classical H1 SIVs, pandemic A(H1N1)2009 (A(H1N1)pdm09) viruses, and seasonal human-lineage SIVs isolated in Japan and Vietnam. A hemagglutination inhibition (HI) assay was used to determine antigenic differences that differentiate the recent Japanese H1N2 and H3N2 SIVs from the H1N1 and H3N2 domestic vaccine strains. Minor antigenic variation between pig A(H1N1)pdm09 viruses was evident by HI assay using 13 mAbs raised against homologous virus. A Vietnamese H1N2 SIV, whose H1 gene originated from a human strain in the mid-2000s, reacted poorly with post-infection ferret serum against human vaccine strains from 2000-2010. These results provide useful information for selection of optimal strains for SIV vaccine production.
Ramey, Andrew M; Pearce, John M; Ely, Craig R; Guy, Lisa M Sheffield; Irons, David B; Derksen, Dirk V; Ip, Hon S
Twenty avian influenza viruses were isolated from seven wild migratory bird species sampled at St. Lawrence Island, Alaska. We tested predictions based on previous phylogenetic analyses of avian influenza viruses that support spatially dependent trans-hemispheric gene flow and frequent interspecies transmission at a location situated at the Asian-North American interface. Through the application of phylogenetic and genotypic approaches, our data support functional dilution by distance of trans-hemispheric reassortants and interspecific virus transmission. Our study confirms infection of divergent avian taxa with nearly identical avian influenza strains in the wild. Findings also suggest that H16N3 viruses may contain gene segments with unique phylogenetic positions and that further investigation of how host specificity may impact transmission of H13 and H16 viruses is warranted. Copyright © 2010. Published by Elsevier Inc.
de Waal, L. (Leon); S.L. Smits (Saskia); E.J.B. Veldhuis Kroeze (Edwin); G. van Amerongen (Geert); Pohl, M.O. (Marie O.); Osterhaus, A.D.M.E. (Albert D. M. E.); K.J. Stittelaar (Koert)
textabstractHuman respiratory syncytial virus (HRSV) causes substantial morbidity and mortality in vulnerable patients, such as the very young, the elderly, and immunocompromised individuals of any age. Nosocomial transmission of HRSV remains a serious challenge in hospital settings, with
Full Text Available In the last few years, several reassortant subtypes of highly pathogenic avian influenza viruses (HPAI H5Nx have emerged in East Asia. These new viruses, mostly of subtype H5N1, H5N2, H5N6, and H5N8 belonging to clade 18.104.22.168, have been found in several Asian countries and have caused outbreaks in poultry in China, South Korea, and Vietnam. HPAI H5Nx also have spread over considerable distances with the introduction of viruses belonging to the same 22.214.171.124 clade in the U.S. (2014–2015 and in Europe (2014–2015 and 2016–2017. In this paper, we examine the emergence and spread of these new viruses in Asia in relation to published datasets on HPAI H5Nx distribution, movement of migratory waterfowl, avian influenza risk models, and land-use change analyses. More specifically, we show that between 2000 and 2015, vast areas of northeast China have been newly planted with rice paddy fields (3.21 million ha in Heilongjiang, Jilin, and Liaoning in areas connected to other parts of Asia through migratory pathways of wild waterfowl. We hypothesize that recent land use changes in northeast China have affected the spatial distribution of wild waterfowl, their stopover areas, and the wild-domestic interface, thereby altering transmission dynamics of avian influenza viruses across flyways. Detailed studies of the habitat use by wild migratory birds, of the extent of the wild–domestic interface, and of the circulation of avian influenza viruses in those new planted areas may help to shed more light on this hypothesis, and on the possible impact of those changes on the long-distance patterns of avian influenza transmission.
Bárcena, J; Morales, M; Vázquez, B; Boga, J A; Parra, F; Lucientes, J; Pagès-Manté, A; Sánchez-Vizcaíno, J M; Blasco, R; Torres, J M
We have developed a new strategy for immunization of wild rabbit populations against myxomatosis and rabbit hemorrhagic disease (RHD) that uses recombinant viruses based on a naturally attenuated field strain of myxoma virus (MV). The recombinant viruses expressed the RHDV major capsid protein (VP60) including a linear epitope tag from the transmissible gastroenteritis virus (TGEV) nucleoprotein. Following inoculation, the recombinant viruses induced specific antibody responses against MV, RHDV, and the TGEV tag. Immunization of wild rabbits by the subcutaneous and oral routes conferred protection against virulent RHDV and MV challenges. The recombinant viruses showed a limited horizontal transmission capacity, either by direct contact or in a flea-mediated process, promoting immunization of contact uninoculated animals.
Gutiérrez-Bugallo, Gladys; Rodriguez-Roche, Rosmari; Díaz, Gisell; Vázquez, Antonio A; Alvarez, Mayling; Rodríguez, Magdalena; Bisset, Juan A; Guzman, Maria G
While horizontal transmission (human-mosquito-human) of dengue viruses largely determines the epidemiology of the disease, vertical transmission (infected female mosquito- infected offspring) has been suggested as a mechanism that ensures maintenance of the virus during adverse conditions for horizontal transmission to occur. The purpose of this study was to analyze the natural infection of larval stages of Aedes aegypti (Diptera: Culicidae) with the dengue virus (DENV) in Cuba. Here, we report vertical transmission of DENV-3 genotype III in natural populations of Ae. aegypti through RT-PCR detection and serotyping plus sequencing. Our report constitutes the first record of vertical transmission of DENV in Ae. aegypti from Cuba with details of its serotype and genotype. Copyright © 2017 Elsevier B.V. All rights reserved.
Full Text Available Many viral pathogens are persistently transmitted by insect vectors and cause agricultural or health problems. Generally, an insect vector can use autophagy as an intrinsic antiviral defense mechanism against viral infection. Whether viruses can evolve to exploit autophagy to promote their transmission by insect vectors is still unknown. Here, we show that the autophagic process is triggered by the persistent replication of a plant reovirus, rice gall dwarf virus (RGDV in cultured leafhopper vector cells and in intact insects, as demonstrated by the appearance of obvious virus-containing double-membrane autophagosomes, conversion of ATG8-I to ATG8-II and increased level of autophagic flux. Such virus-containing autophagosomes seem able to mediate nonlytic viral release from cultured cells or facilitate viral spread in the leafhopper intestine. Applying the autophagy inhibitor 3-methyladenine or silencing the expression of Atg5 significantly decrease viral spread in vitro and in vivo, whereas applying the autophagy inducer rapamycin or silencing the expression of Torc1 facilitate such viral spread. Furthermore, we find that activation of autophagy facilitates efficient viral transmission, whereas inhibiting autophagy blocks viral transmission by its insect vector. Together, these results indicate a plant virus can induce the formation of autophagosomes for carrying virions, thus facilitating viral spread and transmission by its insect vector. We believe that such a role for virus-induced autophagy is common for vector-borne persistent viruses during their transmission by insect vectors.
Yassine, Hadi M; Al-Natour, Mohammad Q; Lee, Chang-Won; Saif, Yehya M
The triple reassortant H3N2 viruses were isolated for the first time from pigs in 1998 and are known to be endemic in swine and turkey populations in the United States. In 2004, we isolated two H3N2 triple reassortant viruses from two turkey breeder flocks in Ohio and Illinois. Infected hens showed no clinical signs, but experienced a complete cessation of egg production. In this study, we evaluated three triple reassortant H3N2 isolates of turkey origin and one isolate of swine origin for their transmission between swine and turkeys. Although all 4 viruses tested share high genetic similarity in all 8 genes, only the Ohio strain (A/turkey/Ohio/313053/04) was shown to transmit efficiently both ways between swine and turkeys. One isolate, A/turkey/North Carolina/03, was able to transmit from pigs to turkeys but not vice versa. Neither of the other two viruses transmitted either way. Sequence analysis of the HA1 gene of the Ohio strain showed one amino acid change (D to A) at residue 190 of the receptor binding domain upon transmission from turkeys to pigs. The Ohio virus was then tested for intraspecies transmission in three different avian species. The virus was shown to replicate and transmit among turkeys, replicate but does not transmit among chickens, and did not replicate in ducks. Identifying viruses with varying inter- and intra-species transmission potential should be useful for further studies on the molecular basis of interspecies transmission.
Nguyet Minh Nguyen
Full Text Available Primary health care facilities frequently manage dengue cases on an ambulatory basis for the duration of the patient's illness. There is a great opportunity for specific messaging, aimed to reduce dengue virus (DENV transmission in and around the home, to be directly targeted toward this high-risk ambulatory patient group, as part of an integrated approach to dengue management. The extent however, to which physicians understand, and can themselves effectively communicate strategies to stop focal DENV transmission around an ambulatory dengue case is unknown; the matter of patient comprehension and recollection then ensues. In addition, the effectiveness of N,N-diethyl-3-methylbenzamide (DEET-based insect repellent in protecting dengue patients from Aedes aegypti mosquitoes' bites has not been investigated.A knowledge, attitude and practice (KAP survey, focusing on the mechanisms of DENV transmission and prevention, was performed using semi-structured questionnaires. This survey was targeted towards the patients and family members providing supportive care, and physicians routinely involved in dengue patient management in Southern Vietnam. An additional clinical observational study was conducted to measure the efficacy of a widely-used 13% DEET-based insect repellent to repel Ae. aegypti mosquitoes from the forearms of dengue cases and matched healthy controls.Among both the physician (n = 50 and patient (n = 49 groups there were several respondents lacking a coherent understanding of DENV transmission, leading to some inappropriate attitudes and inadequate acute preventive practices in the household. The application of insect repellent to protect patients and their relatives from mosquito bites was frequently recommended by majority of physicians (78% participating in the survey. Nevertheless, our tested topical application of 13% DEET conferred only ~1hr median protection time from Ae. aegypti landing. This is notably shorter than that
Kebede, Yenew; Dorigo-Zetsma, Wendelien; Mengistu, Yohannes; Mekonnen, Yared; Schaap, Ab; Wolday, Dawit; Sanders, Eduard J.; Messele, Tsehaynesh; Coutinho, Roel A.; Dukers, Nicole H. T. M.
The herpes simplex virus type 2 (HSV-2) and human immunodeficiency virus (HIV) epidemics are believed to fuel each other, especially in sub-Saharan countries. In Ethiopia during 1997 - 2002, a retrospective study was conducted to examine risk factors for infection and transmission of HSV-2, in a
Yen, Hui-Ling; Lipatov, Aleksandr S.; Ilyushina, Natalia A.; Govorkova, Elena A.; Franks, John; Yilmaz, Neziha; Douglas, Alan; Hay, Alan; Krauss, Scott; Rehg, Jerold E.; Hoffmann, Erich; Webster, Robert G.
The abilities to infect and transmit efficiently among humans are essential for a novel influenza A virus to cause a pandemic. To evaluate the pandemic potential of widely disseminated H5N1 influenza viruses, a ferret contact model using experimental groups comprised of one inoculated ferret and two contact ferrets was used to study the transmissibility of four human H5N1 viruses isolated from 2003 to 2006. The effects of viral pathogenicity and receptor binding specificity (affinity to synth...
Mulcahy, D.; Pascho, R.J.
The control of epizootics of infectious haematopoietic necrosis (IHN) virus in salmonid fishes is presently based on examination and certification of adult brood fish to prevent the introduction of virus-infected eggs into hatcheries (Canadian Fisheries and Marine Service 1976; McDaniel 1979). This strategy is based on the assumption that the virus is vertically transmitted in association with the gametes. However, evidence for vertical transmission of IHN virus is circumstantial, based mostly on the appearance of the disease outside the enzootic area (the west coast of North America) in fish hatched from eggs obtained from within that area (Plumb 1972; Holway & Smith 1973; Wolf, Quimby, Pettijohn & Landolt 1973; Sano, Nishimura, Okamoto, Yamazaki, Hanada & Watanabe1977; Carlisle, Schat & Elston 1979). An indirect demonstration of vertical transmission was made by placing known virus-free fish in the water above and below raceways containing fish that suffered an IHN epizootic in an effort to eliminate waterborne virus as a source of infection (Wingfield & Chan 1970). The fish placed below the raceway developed IHN, due to waterborne virus released from the affected fish in the raceway, but the fish placed above the raceway failed to develop IHN. These results suggested that the source of infection of the fish in the raceway was not the water supply, although it is possible that the virus was no longer present in the water supply at the time the sentinel fish were exposed to the water.
Van, Song Nguyen; Khac, Minh Nguyen; Dimberg, Jan; Matussek, Andreas; Henningsson, Anna J
The goal of the present study was to determine the prevalence and distribution of high-risk human papilloma virus (HPV) genotypes in women from two districts in and around Da Nang city, Vietnam. All participants were randomly selected, 200 from the Hai Chau district and 200 from the Son Tra district. The detection and genotyping of HPV were performed by real-time polymerase chain reaction (PCR) technique. Out of a total of 400 women, we found that 38 (9.5%) were infected with a high-risk HPV genotype, the most prevalent genotypes being 16, 18, 58 and 59. By assessment of the HPV findings in relation to sociodemographic characteristics, we found significant differences between the two study districts and between the age groups, as well as differences associated with occupation and the use of contraceptives. The proportion of high-risk genotypes other than 16 and 18 was relatively high, and since the HPV genotype distribution is known to vary greatly across populations, the information from this study can be used for planning of screening and vaccination programs in Da Nang. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.
Roermund, van H.J.W.; Eblé, P.L.; Jong, de M.C.M.; Dekker, A.
Many studies have shown transmission of foot-and-mouth disease virus (FMDV) within groups of pigs, even when vaccinated, but only limited information is available on transmission between pens. Three new experiments were carried out in two replicates, which consisted of infectious pigs housed in a
Hartemink, N.A.; Davis, S.A.; Reiter, P.; Hubálek, Z.; Heesterbeek, J.A.P.
West Nile virus (WNV) is principally considered to be maintained in a mosquito–bird transmission cycle. Under experimental conditions, several other transmission routes have been observed, but the significance of these additional routes in nature is unknown. Here, we derive an expression for the
Goris, N.E.; Eble, P.L.; Jong, de M.C.M.; Clercq, K.
Foot-and-mouth disease is an extremely infectious and devastating disease affecting all species of cloven-hoofed animals. To understand the epidemiology of the causative virus and predict viral transmission dynamics, quantified transmission parameters are essential to decision makers and modellers
A B Sudeep
Full Text Available Background & objectives: Bagaza virus (BAGV, a flavivirus synonymous with Israel turkey meningoencephalitis virus, has been found to circulate in India. BAGV has recently been held responsible for inducing febrile illness in humans and causing unusually high mortality to wild birds in Spain. A study was therefore, undertaken to determine its replication kinetics in certain mosquitoes and to determine vector competence and potential of the mosquitoes to transmit BAGV experimentally. Methods: Aedes aegypti, Culex tritaeniorhynchus and Cx quinquefasciatus mosquitoes were inoculated with BAGV; samples were harvested every day and titrated in BHK-21 cell line. Vector competence and experimental transmission were determined by examining the saliva of infected mosquitoes for virus and induction of sickness in suckling mice, respectively. Results: Cx. tritaeniorhynchus and Ae. aegypti mosquitoes yielded 5 log 10 and 4.67 log 10 TCID 50 /ml of virus on day 3 post-infection (PI, respectively while Cx. quinquefasciatus yielded a titre of 4 log 10 TCID 50 /ml on day 4 PI. BAGV was detected in saliva of all the infected mosquitoes demonstrating their vector competence. Experimental transmission of BAGV to infant mice as well as transovarial transmission was demonstrated by Cx. tritaeniorhynchus but not by Ae. aegypti and Cx. quinquefasciatus mosquitoes. Interpretation & conclusions: Replication of BAGV to high titres and dissemination to saliva in three most prevalent mosquitoes in India is of immense public health importance. Though no major outbreak involving man has been reported yet, BAGV has a potential to cause outbreaks in future.
Switchgrass mosaic virus (SwMV) was identified in switchgrass (Panicum virgatum) and was proposed as a new marafivirus based on its genome sequence and comparison with its closest relative, Maize rayado fino virus (MRFV), a type member of the genus, Marafivirus. MRFV only infects maize (Zea mays) an...
Tomato spotted wilt virus (TSWV), member of the genus Tospovirus within the family Bunyaviridae, ranks among the top ten of economically most important plant viruses. Tospoviruses cause significant yield losses in agricultural crops such as tomato,
Lucia Regina Cangussu da Silva
Full Text Available Abstract: The Zika virus epidemic that started in Brazil in 2014 has spread to >30 countries and territories in Latin America, leading to a rapid rise in the incidence of microcephalic newborns and adults with neurological complications. At the beginning of the outbreak, little was known about Zika virus morphology, genome structure, modes of transmission, and its potential to cause neurological malformations and disorders. With the advancement of basic science, discoveries of the mechanisms of strain variability, viral transfer to the fetus, and neurovirulence were published. These will certainly lead to the development of strategies to block vertical viral transmission, neuronal invasion, and pathogenesis in the near future. This paper reviews the current literature on Zika virus infections, with the aim of gaining a holistic insight into their etiology and pathogenesis. We discuss Zika virus history and epidemiology in Brazil, viral structure and taxonomy, old and newly identified transmission modes, and neurological consequences of infection.
Medeiros Sheila de
Full Text Available Abstract Background Feline immunodeficiency virus (FIV is a naturally occurring lentivirus that infects cats. The primary mode of transmission occurs through bite wounds, and other routes are difficult to observe in nature. Findings The purpose of this study was to evaluate FIV transmission from queen to kitten in a colony of naturally infected stray cats. With this aim, a queen was monitored over a period of three years. A blood sample was taken to amplify and sequence gag, pol and env regions of the virus from the queen, two kittens and other cats from the colony. Conclusion Phylogenetic analysis showed evidence of queen to kitten transmission.
Medeiros, Sheila de Oliveira; Martins, Angelica Nascimento; Dias, Carlos Gabriel Almeida; Tanuri, Amilcar; Brindeiro, Rodrigo de Moraes
Feline immunodeficiency virus (FIV) is a naturally occurring lentivirus that infects cats. The primary mode of transmission occurs through bite wounds, and other routes are difficult to observe in nature. The purpose of this study was to evaluate FIV transmission from queen to kitten in a colony of naturally infected stray cats. With this aim, a queen was monitored over a period of three years. A blood sample was taken to amplify and sequence gag, pol and env regions of the virus from the queen, two kittens and other cats from the colony. Phylogenetic analysis showed evidence of queen to kitten transmission.
Full Text Available BACKGROUND & AIMS: In the Netherlands, a selective hepatitis B virus (HBV vaccination programme started in 2002 for men having sex with men, drug users, commercial sex workers and heterosexuals with frequent partner changes. We assessed the programme's effectiveness to guide policy on HBV prevention. METHODS: We analysed reports of acute HBV infection in the Netherlands between 2004 and 2010 requesting serum from patients for HBV-genome S- and C-region sequencing. We used coalescence analyses to assess genetic diversity of nonimported genotype-A cases over time. RESULTS: 1687 patients with acute HBV infection were reported between 2004 and 2010. The incidence of reported acute HBV infection decreased from 1.8 to 1.2 per 100,000 inhabitants, mostly due to a reduction in the number of cases in men who have sex with men. Men were overrepresented among cases with an unknown route of transmission, especially among genotype A2 cases mainly associated with transmission through male homosexual contact. The genetic diversity of nonimported genotype-A strains obtained from men who have sex with men decreased from 2006 onwards, suggesting HBV incidence in this group decreased. CONCLUSIONS: The selective HBV-vaccination programme for behavioural high-risk groups very likely reduced the incidence of HBV infection in the Netherlands mainly by preventing HBV infections in men who have sex with men. A considerable proportion of cases in men who did not report risk behaviour was probably acquired through homosexual contact. Our findings support continuation of the programme, and adopting similar approaches in other countries where HBV transmission is focused in high-risk adults.
Koedijk, Femke; van Ballegooijen, Marijn; Cremer, Jeroen; Bruisten, Sylvia; Coutinho, Roel
Background & Aims In the Netherlands, a selective hepatitis B virus (HBV) vaccination programme started in 2002 for men having sex with men, drug users, commercial sex workers and heterosexuals with frequent partner changes. We assessed the programme's effectiveness to guide policy on HBV prevention. Methods We analysed reports of acute HBV infection in the Netherlands between 2004 and 2010 requesting serum from patients for HBV-genome S- and C-region sequencing. We used coalescence analyses to assess genetic diversity of nonimported genotype-A cases over time. Results 1687 patients with acute HBV infection were reported between 2004 and 2010. The incidence of reported acute HBV infection decreased from 1.8 to 1.2 per 100,000 inhabitants, mostly due to a reduction in the number of cases in men who have sex with men. Men were overrepresented among cases with an unknown route of transmission, especially among genotype A2 cases mainly associated with transmission through male homosexual contact. The genetic diversity of nonimported genotype-A strains obtained from men who have sex with men decreased from 2006 onwards, suggesting HBV incidence in this group decreased. Conclusions The selective HBV-vaccination programme for behavioural high-risk groups very likely reduced the incidence of HBV infection in the Netherlands mainly by preventing HBV infections in men who have sex with men. A considerable proportion of cases in men who did not report risk behaviour was probably acquired through homosexual contact. Our findings support continuation of the programme, and adopting similar approaches in other countries where HBV transmission is focused in high-risk adults. PMID:23922651
Eble, P.L.; Bouma, A.; Bruin, de M.G.M.; Hemert-Kluitenberg, van F.; Oirschot, van J.T.; Dekker, A.
The objective of this study was to investigate whether and at what time interval could vaccination reduce transmission of foot-and-Mouth disease virus (FMDV) among pigs. Reduction of virus transmission by vaccination was determined experimentally. Transmission of FMDV was studied in three groups of
Full Text Available Human immunodeficiency virus type I (HIV-1 infects target cells through interaction with the CD4 molecule and chemokine receptors, mainly CCR5 and CXCR4. Viral isolates can be phenotypically classified based on the co-receptor they utilize to infect target cells. Thus, R5 and X4 virus use respectively CCR5 and CXCR4, whereas R5X4 virus can use either CCR5 or CXCR4. This review describes the central role played by co-receptor expression and usage for HIV-1 cell tropism, transmission and pathogenesis. We discuss various hypotheses proposed to explain the preferential transmission of R5 viruses and the mechanisms driving the change of HIV-1 co-receptor usage in the course of infection. Recent insights in the intrinsic variability of R5 viruses and their role in influencing disease progression in both adults and children are also discussed.
Cavarelli, Mariangela; Scarlatti, Gabriella
Human immunodeficiency virus type I (HIV-1) infects target cells through interaction with the CD4 molecule and chemokine receptors, mainly CCR5 and CXCR4. Viral isolates can be phenotypically classified based on the co-receptor they utilize to infect target cells. Thus, R5 and X4 virus use respectively CCR5 and CXCR4, whereas R5X4 virus can use either CCR5 or CXCR4. This review describes the central role played by co-receptor expression and usage for HIV-1 cell tropism, transmission and pathogenesis. We discuss various hypotheses proposed to explain the preferential transmission of R5 viruses and the mechanisms driving the change of HIV-1 co-receptor usage in the course of infection. Recent insights in the intrinsic variability of R5 viruses and their role in influencing disease progression in both adults and children are also discussed.
Pereira Oliveira, Graziele; Tavares Silva Fernandes, André; Lopes de Assis, Felipe; Augusto Alves, Pedro; Moreira Franco Luiz, Ana Paula; Barcelos Figueiredo, Leandra; Costa de Almeida, Cláudia Maria; Pires Ferreira Travassos, Carlos Eurico; de Souza Trindade, Giliane; Santos Abrahão, Jônatas; Geessien Kroon, Erna
Bovine vaccinia (BV) is an emerging zoonosis caused by the Vaccinia virus (VACV), genus Orthopoxvirus (OPV), Poxviridae family. In general, human cases are related to direct contact with sick cattle but there is a lack of information about human-to-human transmission of VACV during BV outbreaks. In this study, we epidemiologically and molecularly show a case of VACV transmission between humans in São Francisco de Itabapoana County, Rio de Janeiro state. Our group collected samples from the patients, a 49-year-old patient and his son. Our results showed that patients had developed anti-OPV IgG or IgM antibodies and presented neutralizing antibodies against OPV. The VACV isolates displayed high identity (99.9%) and were grouped in the same phylogenetic tree branch. Our data indicate that human-to-human VACV transmission occurred during a BV outbreak, raising new questions about the risk factors of the VACV transmission chain. PMID:24615135
Le, Mai Quynh; Horby, Peter; Fox, Annette; Nguyen, Hien Tran; Le Nguyen, Hang Khanh; Hoang, Phuong Mai Vu; Nguyen, Khanh Cong; de Jong, Menno D.; Jeeninga, Rienk E.; Rogier van Doorn, H.; Farrar, Jeremy; Wertheim, Heiman F. L.
Laboratory-confirmed cases of subclinical infection with avian influenza A(H5N1) virus in humans are rare, and the true number of these cases is unknown. We describe the identification of a laboratory-confirmed subclinical case in a woman during an influenza A(H5N1) contact investigation in northern
Full Text Available Computer viruses remain a significant threat to computer networks. In this paper, the incorporation of new computers to the network and the removing of old computers from the network are considered. Meanwhile, the computers are equipped with antivirus software on the computer network. The computer virus model is established. Through the analysis of the model, disease-free and endemic equilibrium points are calculated. The stability conditions of the equilibria are derived. To illustrate our theoretical analysis, some numerical simulations are also included. The results provide a theoretical basis to control the spread of computer virus.
Belser, Jessica A; Gustin, Kortney M; Pearce, Melissa B; Maines, Taronna R; Zeng, Hui; Pappas, Claudia; Sun, Xiangjie; Carney, Paul J; Villanueva, Julie M; Stevens, James; Katz, Jacqueline M; Tumpey, Terrence M
On 29 March 2013, the Chinese Center for Disease Control and Prevention confirmed the first reported case of human infection with an avian influenza A(H7N9) virus. The recent human infections with H7N9 virus, totalling over 130 cases with 39 fatalities to date, have been characterized by severe pulmonary disease and acute respiratory distress syndrome (ARDS). This is concerning because H7 viruses have typically been associated with ocular disease in humans, rather than severe respiratory disease. This recent outbreak underscores the need to better understand the pathogenesis and transmission of these viruses in mammals. Here we assess the ability of A/Anhui/1/2013 and A/Shanghai/1/2013 (H7N9) viruses, isolated from fatal human cases, to cause disease in mice and ferrets and to transmit to naive animals. Both H7N9 viruses replicated to higher titre in human airway epithelial cells and in the respiratory tract of ferrets compared to a seasonal H3N2 virus. Moreover, the H7N9 viruses showed greater infectivity and lethality in mice compared to genetically related H7N9 and H9N2 viruses. The H7N9 viruses were readily transmitted to naive ferrets through direct contact but, unlike the seasonal H3N2 virus, did not transmit readily by respiratory droplets. The lack of efficient respiratory droplet transmission was corroborated by low receptor-binding specificity for human-like α2,6-linked sialosides. Our results indicate that H7N9 viruses have the capacity for efficient replication in mammals and human airway cells and highlight the need for continued public health surveillance of this emerging virus.
Creanga, Adrian; Hang, Nguyen Le Khanh; Cuong, Vuong Duc; Nguyen, Ha T; Phuong, Hoang Vu Mai; Thanh, Le Thi; Thach, Nguyen Co; Hien, Pham Thi; Tung, Nguyen; Jang, Yunho; Balish, Amanda; Dang, Nguyen Hoang; Duong, Mai Thuy; Huong, Ngo Thu; Hoa, Do Ngoc; Tho, Nguyen Dang; Klimov, Alexander; Kapella, Bryan K; Gubareva, Larisa; Kile, James C; Hien, Nguyen Tran; Mai, Le Quynh; Davis, C Todd
Mutation and reassortment of highly pathogenic avian influenza A(H5N1) viruses at the animal-human interface remain a major concern for emergence of viruses with pandemic potential. To understand the relationship of H5N1 viruses circulating in poultry and those isolated from humans, comprehensive phylogenetic and molecular analyses of viruses collected from both hosts in Vietnam between 2003 and 2010 were performed. We examined the temporal and spatial distribution of human cases relative to H5N1 poultry outbreaks and characterized the genetic lineages and amino acid substitutions in each gene segment identified in humans relative to closely related viruses from avian hosts. Six hemagglutinin clades and 8 genotypes were identified in humans, all of which were initially identified in poultry. Several amino acid mutations throughout the genomes of viruses isolated from humans were identified, indicating the potential for poultry viruses infecting humans to rapidly acquire molecular markers associated with mammalian adaptation and antiviral resistance. Published by Oxford University Press for the Infectious Diseases Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.
U.S. Department of Health & Human Services — Interactive visualization: http://www.cdc.gov/chikungunya/modeling/index.html. This dataset contains monthly predictions for the spread of chikungunya virus...
David F. Attaway
Full Text Available Summary: As evidence linking Zika virus with serious health complications strengthens, public health officials and clinicians worldwide need to know which locations are likely to be at risk for autochthonous Zika infections. We created risk maps for epidemic and endemic Aedes-borne Zika virus infections globally using a predictive analysis method that draws on temperature, precipitation, elevation, land cover, and population density variables to identify locations suitable for mosquito activity seasonally or year-round. Aedes mosquitoes capable of transmitting Zika and other viruses are likely to live year-round across many tropical areas in the Americas, Africa, and Asia. Our map provides an enhanced global projection of where vector control initiatives may be most valuable for reducing the risk of Zika virus and other Aedes-borne infections. Keywords: Geographic information systems, Geographic information science, Risk mapping, Zika, Aedes modeling
Attaway, David F; Waters, Nigel M; Geraghty, Estella M; Jacobsen, Kathryn H
As evidence linking Zika virus with serious health complications strengthens, public health officials and clinicians worldwide need to know which locations are likely to be at risk for autochthonous Zika infections. We created risk maps for epidemic and endemic Aedes-borne Zika virus infections globally using a predictive analysis method that draws on temperature, precipitation, elevation, land cover, and population density variables to identify locations suitable for mosquito activity seasonally or year-round. Aedes mosquitoes capable of transmitting Zika and other viruses are likely to live year-round across many tropical areas in the Americas, Africa, and Asia. Our map provides an enhanced global projection of where vector control initiatives may be most valuable for reducing the risk of Zika virus and other Aedes-borne infections. Copyright © 2016 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.
Background: Serodiscordant couples, have been used to study heterosexual transmission risk because of the high frequency of sexual acts that occur in stable relationships. The hormonal changes during pregnancy could influence heterosexual transmission in serodiscordant relationships. The prevalence of ...
Victor A. Brugman
Full Text Available Over the past three decades, a range of mosquito-borne viruses that threaten public and veterinary health have emerged or re-emerged in Europe. Mosquito surveillance activities have highlighted the Culex pipiens species complex as being critical for the maintenance of a number of these viruses. This species complex contains morphologically similar forms that exhibit variation in phenotypes that can influence the probability of virus transmission. Critical amongst these is the choice of host on which to feed, with different forms showing different feeding preferences. This influences the ability of the mosquito to vector viruses and facilitate transmission of viruses to humans and domestic animals. Biases towards blood-feeding on avian or mammalian hosts have been demonstrated for different Cx. pipiens ecoforms and emerging evidence of hybrid populations across Europe adds another level of complexity to virus transmission. A range of molecular methods based on DNA have been developed to enable discrimination between morphologically indistinguishable forms, although this remains an active area of research. This review provides a comprehensive overview of developments in the understanding of the ecology, behaviour and genetics of Cx. pipiens in Europe, and how this influences arbovirus transmission.
Hernández-Triana, Luis M.; Medlock, Jolyon M.; Fooks, Anthony R.; Carpenter, Simon; Johnson, Nicholas
Over the past three decades, a range of mosquito-borne viruses that threaten public and veterinary health have emerged or re-emerged in Europe. Mosquito surveillance activities have highlighted the Culex pipiens species complex as being critical for the maintenance of a number of these viruses. This species complex contains morphologically similar forms that exhibit variation in phenotypes that can influence the probability of virus transmission. Critical amongst these is the choice of host on which to feed, with different forms showing different feeding preferences. This influences the ability of the mosquito to vector viruses and facilitate transmission of viruses to humans and domestic animals. Biases towards blood-feeding on avian or mammalian hosts have been demonstrated for different Cx. pipiens ecoforms and emerging evidence of hybrid populations across Europe adds another level of complexity to virus transmission. A range of molecular methods based on DNA have been developed to enable discrimination between morphologically indistinguishable forms, although this remains an active area of research. This review provides a comprehensive overview of developments in the understanding of the ecology, behaviour and genetics of Cx. pipiens in Europe, and how this influences arbovirus transmission. PMID:29473903
Li, Hui; Stoddard, Mark B; Wang, Shuyi; Blair, Lily M; Giorgi, Elena E; Parrish, Erica H; Learn, Gerald H; Hraber, Peter; Goepfert, Paul A; Saag, Michael S; Denny, Thomas N; Haynes, Barton F; Hahn, Beatrice H; Ribeiro, Ruy M; Perelson, Alan S; Korber, Bette T; Bhattacharya, Tanmoy; Shaw, George M
A precise molecular identification of transmitted hepatitis C virus (HCV) genomes could illuminate key aspects of transmission biology, immunopathogenesis and natural history. We used single genome sequencing of 2,922 half or quarter genomes from plasma viral RNA to identify transmitted/founder (T/F) viruses in 17 subjects with acute community-acquired HCV infection. Sequences from 13 of 17 acute subjects, but none of 14 chronic controls, exhibited one or more discrete low diversity viral lineages. Sequences within each lineage generally revealed a star-like phylogeny of mutations that coalesced to unambiguous T/F viral genomes. Numbers of transmitted viruses leading to productive clinical infection were estimated to range from 1 to 37 or more (median = 4). Four acutely infected subjects showed a distinctly different pattern of virus diversity that deviated from a star-like phylogeny. In these cases, empirical analysis and mathematical modeling suggested high multiplicity virus transmission from individuals who themselves were acutely infected or had experienced a virus population bottleneck due to antiviral drug therapy. These results provide new quantitative and qualitative insights into HCV transmission, revealing for the first time virus-host interactions that successful vaccines or treatment interventions will need to overcome. Our findings further suggest a novel experimental strategy for identifying full-length T/F genomes for proteome-wide analyses of HCV biology and adaptation to antiviral drug or immune pressures.
Shan, Chao; Muruato, Antonio E; Jagger, Brett W; Richner, Justin; Nunes, Bruno T D; Medeiros, Daniele B A; Xie, Xuping; Nunes, Jannyce G C; Morabito, Kaitlyn M; Kong, Wing-Pui; Pierson, Theodore C; Barrett, Alan D; Weaver, Scott C; Rossi, Shannan L; Vasconcelos, Pedro F C; Graham, Barney S; Diamond, Michael S; Shi, Pei-Yong
Zika virus infection during pregnancy can cause congenital abnormities or fetal demise. The persistence of Zika virus in the male reproductive system poses a risk of sexual transmission. Here we demonstrate that live-attenuated Zika virus vaccine candidates containing deletions in the 3' untranslated region of the Zika virus genome (ZIKV-3'UTR-LAV) prevent viral transmission during pregnancy and testis damage in mice, as well as infection of nonhuman primates. After a single-dose vaccination, pregnant mice challenged with Zika virus at embryonic day 6 and evaluated at embryonic day 13 show markedly diminished levels of viral RNA in maternal, placental, and fetal tissues. Vaccinated male mice challenged with Zika virus were protected against testis infection, injury, and oligospermia. A single immunization of rhesus macaques elicited a rapid and robust antibody response, conferring complete protection upon challenge. Furthermore, the ZIKV-3'UTR-LAV vaccine candidates have a desirable safety profile. These results suggest that further development of ZIKV-3'UTR-LAV is warranted for humans.Zika virus infection can result in congenital disorders and cause disease in adults, and there is currently no approved vaccine. Here Shan et al. show that a single dose of a live-attenuated Zika vaccine prevents infection, testis damage and transmission to the fetus during pregnancy in different animal models.
Yu. V. Ostankova
Full Text Available Aim. Analysis of phylogenetic relationships of HIV isolates obtained from a child 8 years old and HIV-positive parents to search for a possible source of infection.Materials and methods. The blood plasma samples of 3 patients (father, mother and child HIV from Veliky Novgorod were used. Presented in a group of patients were directed to conduct epidemiological investigation cases of HIV-1 infection a child from a dysfunctional family. In the present study we used genotyping by direct sequencing of the site of the polymerase gene (pol length of 1285 nt., The gene encoding the protease (PR length of 465 nt. and a portion of the reverse transcriptase (RT gene length of 820 nt.Results. The study allowed the identification of the HIV virus in clinical samples. HIV-1 subtype A1 (IDU-A was detected in all cases. Phylogenetic analysis of isolates, where the control samples using HIV-1 isolates obtained previously from Veliky Novgorod, possible to identify grouped in a separate cluster sample from the mother, father and child, which makes it possible to conclude about intrafamily HIV infected child by one of his parents. The nucleotide identity of the samples obtained from the mother and the child, showed a higher percentage of similarity – 98.4%, compared with the identity of the samples between the father and the mother and between father and child (96.2% and 94.2%, respectively. Differences natural polymorphisms in protease and reverse transcriptase genes of the parents and the child are discussed. Conclusion. The analysis of phylogenetic relationships of HIV isolates showed that the source of infection of the child 8 years old, born and living in socially disadvantaged families with HIV-positive parents, is his mother. Way parenteral transmission of infection by random simultaneous trauma in the mother and child
Timothy M Uyeki
Full Text Available BACKGROUND: The frequency of avian influenza A virus infections among poultry workers is not well understood. METHODS: A seroprevalence study of market poultry workers and persons without occupational poultry exposure was conducted during 2001 in Hanoi, Vietnam. Sera were tested for avian influenza H5 and H9 antibodies by microneutralization and Western blot assays. RESULTS: Seroprevalence of H5 and H9 antibodies was 4% and 3% in poultry workers and 1% and 3.5% in non-poultry workers, respectively. CONCLUSIONS: Seroprevalence of H5 and H9 antibodies was low among Hanoi market poultry workers in 2001, but can serve as a baseline for additional studies.
Rowe, Thomas; Lu, Xiuhua; Hu-Primmer, Jean; Huynh, Lien P.; Hang, Nguyen L. K.; Katz, Jacqueline M.
Background The frequency of avian influenza A virus infections among poultry workers is not well understood. Methods A seroprevalence study of market poultry workers and persons without occupational poultry exposure was conducted during 2001 in Hanoi, Vietnam. Sera were tested for avian influenza H5 and H9 antibodies by microneutralization and Western blot assays. Results Seroprevalence of H5 and H9 antibodies was 4% and 3% in poultry workers and 1% and 3.5% in non-poultry workers, respectively. Conclusions Seroprevalence of H5 and H9 antibodies was low among Hanoi market poultry workers in 2001, but can serve as a baseline for additional studies. PMID:22928049
Reflections of an Associated Press special correspondent on a return visit to Vietnam 15 years after the war. Discusses the social and economic impact of the war on Vietnam. Examines the plight of the Vietnamese who served in the U.S. military, discussing the problems of Amerasians. Recounts the efforts of U.S. veterans to rebuild Vietnam. (RW)
Full Text Available The ability of influenza A viruses (IAVs to cross species barriers and evade host immunity is a major public health concern. Studies on the phylodynamics of IAVs across different scales - from the individual to the population - are essential for devising effective measures to predict, prevent or contain influenza emergence. Understanding how IAVs spread and evolve during outbreaks is critical for the management of epidemics. Reconstructing the transmission network during a single outbreak by sampling viral genetic data in time and space can generate insights about these processes. Here, we obtained intra-host viral sequence data from horses infected with equine influenza virus (EIV to reconstruct the spread of EIV during a large outbreak. To this end, we analyzed within-host viral populations from sequences covering 90% of the infected yards. By combining gene sequence analyses with epidemiological data, we inferred a plausible transmission network, in turn enabling the comparison of transmission patterns during the course of the outbreak and revealing important epidemiological features that were not apparent using either approach alone. The EIV populations displayed high levels of genetic diversity, and in many cases we observed distinct viral populations containing a dominant variant and a number of related minor variants that were transmitted between infectious horses. In addition, we found evidence of frequent mixed infections and loose transmission bottlenecks in these naturally occurring populations. These frequent mixed infections likely influence the size of epidemics.
Full Text Available 1. Abstract The triple reassortant H3N2 viruses were isolated for the first time from pigs in 1998 and are known to be endemic in swine and turkey populations in the United States. In 2004, we isolated two H3N2 triple reassortant viruses from two turkey breeder flocks in Ohio and Illinois. Infected hens showed no clinical signs, but experienced a complete cessation of egg production. In this study, we evaluated three triple reassortant H3N2 isolates of turkey origin and one isolate of swine origin for their transmission between swine and turkeys. Although all 4 viruses tested share high genetic similarity in all 8 genes, only the Ohio strain (A/turkey/Ohio/313053/04 was shown to transmit efficiently both ways between swine and turkeys. One isolate, A/turkey/North Carolina/03, was able to transmit from pigs to turkeys but not vice versa. Neither of the other two viruses transmitted either way. Sequence analysis of the HA1 gene of the Ohio strain showed one amino acid change (D to A at residue 190 of the receptor binding domain upon transmission from turkeys to pigs. The Ohio virus was then tested for intraspecies transmission in three different avian species. The virus was shown to replicate and transmit among turkeys, replicate but does not transmit among chickens, and did not replicate in ducks. Identifying viruses with varying inter- and intra-species transmission potential should be useful for further studies on the molecular basis of interspecies transmission.
Sabeena, Sasidharanpillai; Bhat, Parvati; Kamath, Veena; Arunkumar, Govindakarnavar
There is strong evidence to suggest vertical and horizontal modes of transmission of human papilloma virus (HPV), an established etiologic agent of cervical cancer. Infants, children, and adults can acquire both high-risk and low-risk infections by birth or by close contact even though HPV is mainly transmitted sexually. A thorough review of the literature was performed to assess the possible non-sexual modes of transmission of HPV. An electronic search of databases for review articles, cross-sectional studies, cohort studies, and case reports on non-sexual modes of transmission among sexually unexposed women and children was carried out using search terms such as "human papilloma virus, HPV, transmission, horizontal transmission, vertical transmission, and fomites". Articles published between 1983 and 2015 were retrieved. Epidemiological and clinical data support various non-sexual modes of transmission especially at the time of birth and by close contact. Even though the role of fomites in the transmission of HPV is not well established, HPV-DNA positivity has been reported in transvaginal ultrasound probes and colposcopes after routine disinfection. Awareness needs to be spread among the public about alternate modes of transmission. For a proper understanding of the exact natural history of HPV infection acquired via the non-sexual route, long-term prospective studies need to be undertaken. © 2017 Japan Society of Obstetrics and Gynecology.
In the last decade, a wide range of avian influenza viruses (AIVs) have infected various mammalian hosts and continuously threaten both human and animal health. It is a result of overcoming the inter-species barrier which is mostly associated with gene reassortment and accumulation of mutations in their gene segments. Several recent studies have shed insights into the phenotypic and genetic changes that are involved in the interspecies transmission of AIVs. These studies have a major focus on transmission from avian to mammalian species due to the high zoonotic potential of the viruses. As more mammalian species have been infected with these viruses, there is higher risk of genetic evolution of these viruses that may lead to the next human pandemic which represents and raises public health concern. Thus, understanding the mechanism of interspecies transmission and molecular determinants through which the emerging AIVs can acquire the ability to transmit to humans and other mammals is an important key in evaluating the potential risk caused by AIVs among humans. Here, we summarize previous and recent studies on molecular markers that are specifically involved in the transmission of avian-derived influenza viruses to various mammalian hosts including humans, pigs, horses, dogs, and marine mammals. PMID:29236050
Jong, E de; Peters, A.M.; Rahamat-Langendoen, J.C.; Blijlevens, N.M.A.
Immunocompromised patients are especially at risk for developing chronic hepatitis E virus (HEV) infection, which may result in progressive liver disease and cirrhosis. In addition, treatment of chronic HEV infection in these patients often includes dose reduction of immunosuppressive therapy and
Poel, van der W.H.M.
Abstract Hepatitis E virus (HEV), genus Hepevirus, family hepeviridae is a main cause of epidemic hepatitis in developing countries and single cases of hepatitis in higher income countries. There are at least four HEV genotypes which have different epidemiologic and clinical features. Hepatitis E
Vogels, Chantal B.F.; Hartemink, Nienke; Koenraadt, Constantianus J.M.
West Nile virus (WNV) is a mosquito-borne flavivirus which has caused repeated outbreaks in humans in southern and central Europe, but thus far not in northern Europe. The main mosquito vector for WNV, Culex pipiens, consists of two behaviourally distinct biotypes, pipiens and molestus, which can
Dec 29, 2008 ... soil nutrients, altitude and temperature on the biology of maize streak virus (MSV) / vector populations is discussed. ... status of maize host plants and its effects on population dynamics of Cicadulina mbila Naudé. (Homoptera: ..... time necessary for the leafhopper to reach the mesophyll of the leaf and ingest ...
Full Text Available A mosaic disease of pumpkin (Cucurbita maxima was spread widely in Sulawesi. Since the virus had not yet been identified, a study was conducted to identify the disease through mechanical inoculation, aphid vector transmission, host range, and electron microscopic test. Crude sap of infected pumpkin leaf samples was rubbed on the cotyledons of healthy pumpkin seedlings for mechanical inoculation. For insect transmission, five infective aphids were infected per seedling. Seedlings of eleven different species were inoculated mechanically for host range test. Clarified sap was examined under the electron microscope. Seeds of two pumpkin fruits from two different infected plants were planted and observed for disease transmission up to one-month old seedlings. The mosaic disease was transmitted mechanically from crude sap of different leaf samples to healthy pumpkin seedlings showing mosaic symptoms. The virus also infected eight cucurbits, i.e., cucumber (Cucumis sativus, green melon (Cucumis melo, orange/rock melon (C. melo, zucchini (Cucurbita pepo, pumpkin (Cucurbita maxima, water melon (Citrulus vulgaris, Bennicosa hispida, and blewah (Cucurbita sp.. Aphids transmitted the disease from one to other pumpkin seedlings. The virus was not transmitted by seed. The mosaic disease of pumpkin at Maros, South Sulawesi, was associated with flexious particles of approximately 750 nm length, possibly a potyvirus, such as water melon mosaic virus rather than papaya ringspot virus or zucchini yellow mosaic virus.
Naveen K Vaidya
Full Text Available Baiyangdian (BYD virus is a recently-identified mosquito-borne flavivirus that causes severe disease in ducks, with extremely rapid transmission, up to 15% mortality within 10 days and 90% reduction in egg production on duck farms within 5 days of infection. Because of the zoonotic nature of flaviviruses, the characterization of BYD virus and its epidemiology are important public health concerns. Here, we develop a mathematical model for the transmission dynamics of this novel virus. We validate the model against BYD outbreak data collected from duck farms in Southeast China, as well as experimental data obtained from an animal facility. Based on our model, the basic reproductive number of BYD virus is high (R(0 = 21 indicating that this virus is highly transmissible, consistent with the dramatic epidemiology observed in BYDV-affected duck farms. Our results indicate that younger ducks are more vulnerable to BYD disease and that ducks infected with BYD virus reduce egg production (to about 33% on average for about 3 days post-infection; after 3 days infected ducks are no longer able to produce eggs. Using our model, we predict that control measures which reduce contact between mosquitoes and ducks such as mosquito nets are more effective than insecticides.
Full Text Available Background. An international spread of Zika virus (ZIKV infection has attracted global attention. ZIKV is conveyed by a mosquito vector, Aedes species, which also acts as the vector species of dengue and chikungunya viruses. Methods. Arrival time of ZIKV importation (i.e., the time at which the first imported case was diagnosed in each imported country was collected from publicly available data sources. Employing a survival analysis model in which the hazard is an inverse function of the effective distance as informed by the airline transportation network data, and using dengue and chikungunya virus transmission data, risks of importation and local transmission were estimated. Results. A total of 78 countries with imported case(s have been identified, with the arrival time ranging from 1 to 44 weeks since the first ZIKV was identified in Brazil, 2015. Whereas the risk of importation was well explained by the airline transportation network data, the risk of local transmission appeared to be best captured by additionally accounting for the presence of dengue and chikungunya viruses. Discussion. The risk of importation may be high given continued global travel of mildly infected travelers but, considering that the public health concerns over ZIKV infection stems from microcephaly, it is more important to focus on the risk of local and widespread transmission that could involve pregnant women. The predicted risk of local transmission was frequently seen in tropical and subtropical countries with dengue or chikungunya epidemic experience.
Campbell, Karen M.; Haldeman, Kristin; Lehnig, Chris; Munayco, Cesar V.; Halsey, Eric S.; Laguna-Torres, V. Alberto; Yagui, Mart?n; Morrison, Amy C.; Lin, Chii-Dean; Scott, Thomas W.
Background Dengue is one of the most aggressively expanding mosquito-transmitted viruses. The human burden approaches 400 million infections annually. Complex transmission dynamics pose challenges for predicting location, timing, and magnitude of risk; thus, models are needed to guide prevention strategies and policy development locally and globally. Weather regulates transmission-potential via its effects on vector dynamics. An important gap in understanding risk and roadblock in model devel...
Wasmo Wakmana; M.S. Kontong; D.S. Teakle; D.M. Persley
A mosaic disease of pumpkin (Cucurbita maxima) was spread widely in Sulawesi. Since the virus had not yet been identified, a study was conducted to identify the disease through mechanical inoculation, aphid vector transmission, host range, and electron microscopic test. Crude sap of infected pumpkin leaf samples was rubbed on the cotyledons of healthy pumpkin seedlings for mechanical inoculation. For insect transmission, five infective aphids were infected per seedling. Seedlings of eleven di...
Wakmana, Wasmo; Kontong, M.S; Teakle, D.S; Persley, D.M
A mosaic disease of pumpkin (Cucurbita maxima) was spread widely in Sulawesi. Since the virus had not yet been identified, a study was conducted to identify the disease through mechanical inoculation, aphid vector transmission, host range, and electron microscopic test. Crude sap of infected pumpkin leaf samples was rubbed on the cotyledons of healthy pumpkin seedlings for mechanical inoculation. For insect transmission, five infective aphids were infected per seedling. Seedlings of eleven di...
Bronwyn A Clayton
Full Text Available Person-to-person transmission is a key feature of human Nipah virus outbreaks in Bangladesh. In contrast, in an outbreak of Nipah virus in Malaysia, people acquired infections from pigs. It is not known whether this important epidemiological difference is driven primarily by differences between NiV Bangladesh (NiV-BD and Malaysia (NiV-MY at a virus level, or by environmental or host factors. In a time course study, ferrets were oronasally exposed to equivalent doses of NiV-BD or NiV-MY. More rapid onset of productive infection and higher levels of virus replication in respiratory tract tissues were seen for NiV-BD compared to NiV-MY, corroborating our previous report of increased oral shedding of NiV-BD in ferrets and suggesting a contributory mechanism for increased NiV-BD transmission between people compared to NiV-MY. However, we recognize that transmission occurs within a social and environmental framework that may have an important and differentiating role in NiV transmission rates. With this in mind, ferret-to-ferret transmission of NiV-BD and NiV-MY was assessed under differing viral exposure conditions. Transmission was not identified for either virus when naïve ferrets were cohoused with experimentally-infected animals. In contrast, all naïve ferrets developed acute infection following assisted and direct exposure to oronasal fluid from animals that were shedding either NiV-BD or NiV-MY. Our findings for ferrets indicate that, although NiV-BD may be shed at higher levels than NiV-MY, transmission risk may be equivalently low under exposure conditions provided by cohabitation alone. In contrast, active transfer of infected bodily fluids consistently results in transmission, regardless of the virus strain. These observations suggest that the risk of NiV transmission is underpinned by social and environmental factors, and will have practical implications for managing transmission risk during outbreaks of human disease.
Aliota, Matthew T; Peinado, Stephen A; Velez, Ivan Dario; Osorio, Jorge E
Zika virus (ZIKV) is causing an explosive outbreak of febrile disease in the Americas. There are no effective antiviral therapies or licensed vaccines for this virus, and mosquito control strategies have not been adequate to contain the virus. A promising candidate for arbovirus control and prevention relies on the introduction of the intracellular bacterium Wolbachia into Aedes aegypti mosquitoes. This primarily has been proposed as a tool to control dengue virus (DENV) transmission; however, evidence suggests Wolbachia infections confer protection for Ae. aegypti against other arboviruses. At present, it is unknown whether or not ZIKV can infect, disseminate, and be transmitted by Wolbachia-infected Ae. aegypti. Using Ae. aegypti infected with the wMel strain of Wolbachia that are being released in Medellin, Colombia, we report that these mosquitoes have reduced vector competence for ZIKV. These results support the use of Wolbachia biocontrol as a multivalent strategy against Ae. aegypti-transmitted viruses.
Karlsson, Erik A.; Ip, Hon S.; Hall, Jeffrey S.; Yoon, Sun W.; Johnson, Jordan; Beck, Melinda A.; Webby, Richard J.; Schultz-Cherry, Stacey
The ongoing human H7N9 influenza infections highlight the threat of emerging avian influenza viruses. In 2011, an avian H3N8 influenza virus isolated from moribund New England harbour seals was shown to have naturally acquired mutations known to increase the transmissibility of highly pathogenic H5N1 influenza viruses. To elucidate the potential human health threat, here we evaluate a panel of avian H3N8 viruses and find that the harbour seal virus displays increased affinity for mammalian receptors, transmits via respiratory droplets in ferrets and replicates in human lung cells. Analysis of a panel of human sera for H3N8 neutralizing antibodies suggests that there is no population-wide immunity to these viruses. The prevalence of H3N8 viruses in birds and multiple mammalian species including recent isolations from pigs and evidence that it was a past human pandemic virus make the need for surveillance and risk analysis of these viruses of public health importance.
Sharing of toothbrushes among siblings was found to be a significantly associated risk factor. Only 6.4% of mothers knew their hepatitis B status. Conclusion: There is a gradual fall in the prevalence of HBsAg in our environment due to HB immunization. Sharing of toothbrushes may be a potent means of transmission of HBV ...
Yoon, I.K.; Getis, A.; Aldstadt, J.; Rothman, A.L.; Tannitisupawong, D.; Koenraadt, C.J.M.; Fansiri, T.; Jones, J.W.; Morrison, A.C.; Jarman, R.G.; Nisalak, A.; Mammen Jr., M.P.; Thammapalo, S.; Srikiatkhachorn, A.; Green, S.; Libraty, D.H.; Gibbons, R.V.; Endy, T.; Pimgate, C.; Scott, T.W.
Background Based on spatiotemporal clustering of human dengue virus (DENV) infections, transmission is thought to occur at fine spatiotemporal scales by horizontal transfer of virus between humans and mosquito vectors. To define the dimensions of local transmission and quantify the factors that
Saeland, E.; Jong, de M.A.W.P.; Nabatov, A.; Kalay, H.; Kooijk, van Y.; Geijtenbeek, T.B.H.
Mother-to-child transmission of human immunodeficiency virus-1 (HIV-1) occurs frequently via breast-feeding. HIV-1 targets DC-SIGN+ dendritic cells (DCs) in mucosal areas that allow efficient transmission of the virus to T cells. Here, we demonstrate that the epithelial mucin MUC1, abundant in milk,
Full Text Available Many animal and plant viruses rely on vectors for their transmission from host to host. Grapevine fanleaf virus (GFLV, a picorna-like virus from plants, is transmitted specifically by the ectoparasitic nematode Xiphinema index. The icosahedral capsid of GFLV, which consists of 60 identical coat protein subunits (CP, carries the determinants of this specificity. Here, we provide novel insight into GFLV transmission by nematodes through a comparative structural and functional analysis of two GFLV variants. We isolated a mutant GFLV strain (GFLV-TD poorly transmissible by nematodes, and showed that the transmission defect is due to a glycine to aspartate mutation at position 297 (Gly297Asp in the CP. We next determined the crystal structures of the wild-type GFLV strain F13 at 3.0 Å and of GFLV-TD at 2.7 Å resolution. The Gly297Asp mutation mapped to an exposed loop at the outer surface of the capsid and did not affect the conformation of the assembled capsid, nor of individual CP molecules. The loop is part of a positively charged pocket that includes a previously identified determinant of transmission. We propose that this pocket is a ligand-binding site with essential function in GFLV transmission by X. index. Our data suggest that perturbation of the electrostatic landscape of this pocket affects the interaction of the virion with specific receptors of the nematode's feeding apparatus, and thereby severely diminishes its transmission efficiency. These data provide a first structural insight into the interactions between a plant virus and a nematode vector.
Adams, Laura; Bello-Pagan, Melissa; Lozier, Matthew; Ryff, Kyle R; Espinet, Carla; Torres, Jomil; Perez-Padilla, Janice; Febo, Mitchelle Flores; Dirlikov, Emilio; Martinez, Alma; Munoz-Jordan, Jorge; Garcia, Myriam; Segarra, Marangely Olivero; Malave, Graciela; Rivera, Aidsa; Shapiro-Mendoza, Carrie; Rosinger, Asher; Kuehnert, Matthew J; Chung, Koo-Whang; Pate, Lisa L; Harris, Angela; Hemme, Ryan R; Lenhart, Audrey; Aquino, Gustavo; Zaki, Sherif; Read, Jennifer S; Waterman, Stephen H; Alvarado, Luisa I; Alvarado-Ramy, Francisco; Valencia-Prado, Miguel; Thomas, Dana; Sharp, Tyler M; Rivera-Garcia, Brenda
Zika virus is a flavivirus transmitted primarily by Aedes aegypti and Aedes albopictus mosquitoes, and infection can be asymptomatic or result in an acute febrile illness with rash (1). Zika virus infection during pregnancy is a cause of microcephaly and other severe birth defects (2). Infection has also been associated with Guillain-Barré syndrome (GBS) (3) and severe thrombocytopenia (4,5). In December 2015, the Puerto Rico Department of Health (PRDH) reported the first locally acquired case of Zika virus infection. This report provides an update to the epidemiology of and public health response to ongoing Zika virus transmission in Puerto Rico (6,7). A confirmed case of Zika virus infection is defined as a positive result for Zika virus testing by reverse transcription-polymerase chain reaction (RT-PCR) for Zika virus in a blood or urine specimen. A presumptive case is defined as a positive result by Zika virus immunoglobulin M (IgM) enzyme-linked immunosorbent assay (MAC-ELISA)* and a negative result by dengue virus IgM ELISA, or a positive test result by Zika IgM MAC-ELISA in a pregnant woman. An unspecified flavivirus case is defined as positive or equivocal results for both Zika and dengue virus by IgM ELISA. During November 1, 2015-July 7, 2016, a total of 23,487 persons were evaluated by PRDH and CDC Dengue Branch for Zika virus infection, including asymptomatic pregnant women and persons with signs or symptoms consistent with Zika virus disease or suspected GBS; 5,582 (24%) confirmed and presumptive Zika virus cases were identified. Persons with Zika virus infection were residents of 77 (99%) of Puerto Rico's 78 municipalities. During 2016, the percentage of positive Zika virus infection cases among symptomatic males and nonpregnant females who were tested increased from 14% in February to 64% in June. Among 9,343 pregnant women tested, 672 had confirmed or presumptive Zika virus infection, including 441 (66%) symptomatic women and 231 (34%) asymptomatic
Sluijs, van der M.T.W.; Schroer-Joosten, D.P.H.; Fid-Fourkour, A.; Vrijenhoek, M.P.; Debyser, I.; Moulin, V.; Moormann, R.J.M.; Smit, de A.J.
The Bluetongue virus serotype 8 (BTV-8) strain, which emerged in Europe in 2006, had an unusually high ability to cause foetal infection in pregnant ruminants. Other serotypes of BTV had already been present in Europe for more than a decade, but transplacental transmission of these strains had never
Intervention methods to control the transmission of noroviruses and other enteric and respiratory viruses
Human noroviruses are the leading cause of acute and outbreak associated gastroenteritis worldwide. The outbreaks
Nielsen, Sandra Cathrine Abel; Mourier, Tobias; Baandrup, Ulrik
In 2010, a chimpanzee died at Copenhagen Zoo following an outbreak of respiratory disease among chimpanzees in the zoo. Identification of coxsackie B3 virus, a common human pathogen, as the causative agent, and its severe manifestation, raise questions about pathogenicity and transmissibility among...
Dr. Mike Miller reads an abridged version of the article, Dengue Virus Transmission by Blood Stem Cell Donor after Travel to Sri Lanka; Germany, 2013. Created: 9/22/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID). Date Released: 10/8/2014.
Lewis, D.E.; Yoffe, B.; Bosworth, C.G.; Hollinger, F.B.; Rich, R.R.
Epidemiological data suggest that transmission of human immunodeficiency virus (HIV) occurs primarily by transference of virally infected cells. However, the efficiency of lytic productive infection induced by HIV after transmission of cell-associated virus vs. free virus is difficult to assess. The present studies compare the extent of depletion of CD4+ (helper/inducer) T cells after mixing uninfected cells with either free HIV or irradiated HIV-infected allogeneic or autologous cells in vitro. Rapid CD4+ cellular depletion occurred only in cultures containing allogeneic infected cells or after addition of a nonspecific T cell activation signal to cultures with autologous infected cells. These in vitro observations strongly support the epidemiological implication that interactions between infected and uninfected cells are the most efficient means of transmission and HIV-induced cytopathology in vivo. They also provide direct support for the concept that immunological stimulation by foreign cells infected with HIV dramatically increases the likelihood of transmission. These in vitro observations suggest a model for the acquisition of HIV in vivo and the role of cellular activation in dissemination of the virus to uninfected cells in an infected individual
William Hale reads an abridged version of the Emerging Infectious Diseasesâ dispatch, West Nile Virus RNA in Tissues from Donor Associated with Transmission to Organ Transplant Recipients. Created: 11/19/2013 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID). Date Released: 11/21/2013.
Lee, Justin; Malmberg, Jennifer L; Wood, Britta A; Hladky, Sahaja; Troyer, Ryan; Roelke, Melody; Cunningham, Mark; McBride, Roy; Vickers, Winston; Boyce, Walter; Boydston, Erin; Serieys, Laurel; Riley, Seth; Crooks, Kevin; VandeWoude, Sue
Owing to a complex history of host-parasite coevolution, lentiviruses exhibit a high degree of species specificity. Given the well-documented viral archeology of human immunodeficiency virus (HIV) emergence following human exposures to simian immunodeficiency virus (SIV), an understanding of processes that promote successful cross-species lentiviral transmissions is highly relevant. We previously reported natural cross-species transmission of a subtype of feline immunodeficiency virus, puma lentivirus A (PLVA), between bobcats ( Lynx rufus ) and mountain lions ( Puma concolor ) for a small number of animals in California and Florida. In this study, we investigate host-specific selection pressures, within-host viral fitness, and inter- versus intraspecies transmission patterns among a larger collection of PLV isolates from free-ranging bobcats and mountain lions. Analyses of proviral and viral RNA levels demonstrate that PLVA fitness is severely restricted in mountain lions compared to that in bobcats. We document evidence of diversifying selection in three of six PLVA genomes from mountain lions, but we did not detect selection among 20 PLVA isolates from bobcats. These findings support the hypothesis that PLVA is a bobcat-adapted virus which is less fit in mountain lions and under intense selection pressure in the novel host. Ancestral reconstruction of transmission events reveals that intraspecific PLVA transmission has occurred among panthers ( Puma concolor coryi ) in Florida following the initial cross-species infection from bobcats. In contrast, interspecific transmission from bobcats to mountain lions predominates in California. These findings document outcomes of cross-species lentiviral transmission events among felids that compare to the emergence of HIV from nonhuman primates. IMPORTANCE Cross-species transmission episodes can be singular, dead-end events or can result in viral replication and spread in the new species. The factors that determine which
Orsel, K.; Dekker, A.; Bouma, A.; Stegeman, J.A.; Jong, de M.C.M.
Sheep are well known to be susceptible for foot and mouth disease virus (FMDV), but it is unknown whether the infection can spread and persist in a sheep population. We therefore quantified virus transmission by performing experiments with FMD virus strain O/NET/2001 in groups of lambs. We used six
Ngo Xuan, T.; Verreth, J.A.J.; Vlak, J.M.; Jong, de M.C.M.
White spot syndrome virus (WSSV), a rod-shaped double-stranded DNA virus, is an infectious agent causing fatal disease in shrimp farming around the globe. Within shrimp populations WSSV is transmitted very fast, however, the modes and dynamics of transmission of this virus are not well understood.
Rozado-Aguirre, Zuriñe; Adams, Ian; Collins, Larissa; Fox, Adrian; Dickinson, Matthew; Boonham, Neil
A new Torradovirus tentatively named Carrot torrado virus (CaTV) was an incidental finding following a next generation sequencing study investigating internal vascular necrosis in carrot. The closest related viruses are Lettuce necrotic leaf curl virus (LNLCV) found in the Netherlands in 2011 and Motherwort yellow mottle virus (MYMoV) found in Korea in 2014. Primers for reverse transcriptase-PCR (RT-PCR) and RT-qPCR were designed with the aim of testing for the presence of virus in plant samples collected from the field. Both methods successfully amplified the target from infected samples but not from healthy control samples. The specificity of the CaTV assay was also checked against other known carrot viruses and no cross-reaction was seen. A comparative study between methods showed RT-qPCR was the most reliable method, giving positive results in samples where RT-PCR fails. Evaluation of the Ct values following RT-qPCR and a direct comparison demonstrated this was due to improved sensitivity. The previous published Torradovirus genus specific RT-PCR primers were tested and shown to detect CaTV. Also, virus transmission experiments carried out suggest that unlike other species of the same genus, Carrot torrado virus could be aphid-transmitted. Copyright © 2016 Elsevier B.V. All rights reserved.
Lumley, Sarah; Horton, Daniel L; Hernandez-Triana, Luis L M; Johnson, Nicholas; Fooks, Anthony R; Hewson, Roger
Rift Valley fever virus (RVFV) is a mosquito-borne arbovirus causing severe disease in humans and ruminants. Spread of RVFV out of Africa has raised concerns that it could emerge in Europe or the USA. Virus persistence is dependent on successful infection of, replication in, and transmission to susceptible vertebrate and invertebrate hosts, modulated by virus-host and vector-virus interactions. The principal accepted theory for the long-term maintenance of RVFV involves vertical transmission (VT) of virus to mosquito progeny, with the virus surviving long inter-epizootic periods within the egg. This VT hypothesis, however, is yet to be comprehensively proven. Here, evidence for and against the VT of RVFV is reviewed along with the identification of factors limiting its detection in natural and experimental data. The observations of VT for other arboviruses in the genera Alphavirus, Flavivirus and Orthobunyavirus are discussed within the context of RVFV. The review concludes that VT of RVFV is likely but that current data are insufficient to irrefutably prove this hypothesis.
Full Text Available Despite considerable research efforts, little is yet known about key epidemiological parameters of H5N1 highly pathogenic influenza viruses in their avian hosts. Here we show how these parameters can be estimated using a limited number of birds in experimental transmission studies. Our quantitative estimates, based on Bayesian methods of inference, reveal that (i the period of latency of H5N1 influenza virus in unvaccinated chickens is short (mean: 0.24 days; 95% credible interval: 0.099-0.48 days; (ii the infectious period of H5N1 virus in unvaccinated chickens is approximately 2 days (mean: 2.1 days; 95%CI: 1.8-2.3 days; (iii the reproduction number of H5N1 virus in unvaccinated chickens need not be high (mean: 1.6; 95%CI: 0.90-2.5, although the virus is expected to spread rapidly because it has a short generation interval in unvaccinated chickens (mean: 1.3 days; 95%CI: 1.0-1.5 days; and (iv vaccination with genetically and antigenically distant H5N2 vaccines can effectively halt transmission. Simulations based on the estimated parameters indicate that herd immunity may be obtained if at least 80% of chickens in a flock are vaccinated. We discuss the implications for the control of H5N1 avian influenza virus in areas where it is endemic.
Rebekah J Kent
Full Text Available BACKGROUND: The natural history and potential impact of mosquito-specific flaviviruses on the transmission efficiency of West Nile virus (WNV is unknown. The objective of this study was to determine whether or not prior infection with Culex flavivirus (CxFV Izabal altered the vector competence of Cx. quinquefasciatus Say for transmission of a co-circulating strain of West Nile virus (WNV from Guatemala. METHODS AND FINDINGS: CxFV-negative Culex quinquefasciatus and those infected with CxFV Izabal by intrathoracic inoculation were administered WNV-infectious blood meals. Infection, dissemination, and transmission of WNV were measured by plaque titration on Vero cells of individual mosquito bodies, legs, or saliva, respectively, two weeks following WNV exposure. Additional groups of Cx. quinquefasciatus were intrathoracically inoculated with WNV alone or WNV+CxFV Izabal simultaneously, and saliva collected nine days post inoculation. Growth of WNV in Aedes albopictus C6/36 cells or Cx. quinquefasciatus was not inhibited by prior infection with CxFV Izabal. There was no significant difference in the vector competence of Cx. quinquefasciatus for WNV between mosquitoes uninfected or infected with CxFV Izabal across multiple WNV blood meal titers and two colonies of Cx. quinquefasciatus (p>0.05. However, significantly more Cx. quinquefasciatus from Honduras that were co-inoculated simultaneously with both viruses transmitted WNV than those inoculated with WNV alone (p = 0.0014. Co-inoculated mosquitoes that transmitted WNV also contained CxFV in their saliva, whereas mosquitoes inoculated with CxFV alone did not contain virus in their saliva. CONCLUSIONS: In the sequential infection experiments, prior infection with CxFV Izabal had no significant impact on WNV replication, infection, dissemination, or transmission by Cx. quinquefasciatus, however WNV transmission was enhanced in the Honduras colony when mosquitoes were inoculated simultaneously with
Full Text Available Rice stripe mosaic virus (RSMV is a newly discovered species of cytorhabdovirus infecting rice plants that is transmitted by the leafhopper Recilia dorsalis. In this study, the transmission characteristics of RSMV by R. dorsalis were investigated. Under suitable growth conditions for R. dorsalis, the RSMV acquisition rate reached 71.9% in the second-generation population raised on RSMV-infected rice plants. The minimum acquisition and inoculation access periods of R. dorsalis were 3 and 30 min, respectively. The minimum and maximum latent transmission periods of RSMV in R. dorsalis were 6 and 18 d, respectively, and some R. dorsalis intermittently transmitted RSMV at 2–6 d intervals. Our findings revealed that the virus can replicate in the leafhopper body, but is likely not transovarially transmitted to offspring. These transmission characteristics will help guide the formulation of RSMV prevention and control strategies.
Bao, L.M., E-mail: firstname.lastname@example.org [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhang, G.L., E-mail: email@example.com [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Lei, Q.T.; Li, Y.; Li, X.L. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Hwu, Y.K. [Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Yi, J.M. [Advanced Photon Source, Argonne National Laboratory, Argonne 60439 (United States)
For control of influenza, firstly it is important to find the real virus transmission media. Atmospheric aerosol particles are presumably one of the media. In this study, three typical atmospheric inhaled particles in Shanghai were studied by the synchrotron based transmission X-ray microscopes (TXM). Three dimensional microstructure of the particles reveals that there are many pores contained in, particularly the coal combustion fly particles which may be possible virus carrier. The particles can transport over long distance and cause long-range infections due to its light weight. We suggest a mode which is droplet combining with aerosol mode. By this mode the transmission of global and pandemic influenzas and infection between inland avian far from population and poultry or human living in cities along coast may be explained.
Mead, Daniel G; Howerth, Elizabeth W; Murphy, Molly D; Gray, Elmer W; Noblet, Raymond; Stallknecht, David E
The transmission routes of Vesicular stomatitis New Jersey virus (VSNJV), a causative agent of vesicular stomatitis, an Office International des Epizooties List-A disease, are not completely understood. Epidemiological and entomological studies conducted during the sporadic epidemics in the western United States have identified potential virus transmission routes involving insect vectors and animal-to-animal contact. In the present study we experimentally tested the previously proposed transmission routes which were primarily based on field observations. Results obtained provide strong evidence for the following: (1) hematophagous insects acquire VSNJV by unconventional routes while blood feeding on livestock, (2) clinical course of VSNJV infection in livestock following transmission by an infected insect is related to insect bite site, (3) infection of livestock via insect bite can result in multiple transmission possibilities, including animal-to-animal contact. Taken together, these data significantly add to our understanding of the transmission routes of a causative agent of one of the oldest known infectious diseases of livestock, for which the details have remained largely unknown despite decades of research.
Terebuh, Pauline; Olsen, Christopher W; Wright, Jennifer; Klimov, Alexander; Karasin, Alexander; Todd, Karla; Zhou, Hong; Hall, Henrietta; Xu, Xiyan; Kniffen, Tim; Madsen, David; Garten, Rebecca; Bridges, Carolyn B
Triple-reassortant (tr) viruses of human, avian, and swine origin, including H1N1, H1N2, and H3N2 subtypes, emerged in North American swine herds in 1998 and have become predominant. While sporadic human infections with classical influenza A (H1N1) and with tr-swine influenza viruses have been reported, relatively few have been documented in occupationally exposed swine workers (SW). We conducted a 2-year (2002-2004) prospective cohort study of transmission of influenza viruses between pigs and SW from a single pork production company in Iowa. Respiratory samples were collected and tested for influenza viruses from SW and from pigs under their care through surveillance for influenza-like illnesses (ILI). Serial blood samples from study participants were tested by hemagglutination inhibition (HI) for antibody seroconversion against human and swine influenza viruses (SIV), and antibody seroprevalence was compared to age-matched urban Iowa blood donors. During the first year, 15 of 88 SW had ILI and were sampled; all were culture-negative for influenza. During the second year, 11 of 76 SW had ILI and were sampled; one was culture-positive for a human seasonal H3N2 virus. Among 20 swine herd ILI outbreaks sampled, influenza A virus was detected by rRT-PCR from 17 with 11 trH1N1 and five trH3N2 virus isolates cultured. During both years, HI geometric mean titers were significantly higher among SW compared to blood donor controls for three SIV: classical swine Sw/WI/238/97 (H1N1), tr Sw/IN/9K035/99 (H1N2), and trSw/IA/H02NJ56371/02 (H1N1)] (P influenza viruses and were exposed to diverse influenza virus strains circulating in pigs. Influenza virus surveillance among pigs and SW should be encouraged to better understand cross-species transmission and diversity of influenza viruses at the human-swine interface. © 2010 Blackwell Publishing Ltd.
van Tienen, Carla; McConkey, Samuel J.; de Silva, Thushan I.; Cotten, Matthew; Kaye, Steve; Sarge-Njie, Ramu; da Costa, Carlos; Gonçalves, Nato; Parker, Julia; Vincent, Tim; Jaye, Assan; Aaby, Peter; Whittle, Hilton; Schim van der Loeff, Maarten
The relative importance of routes of transmission of human T cell lymphotropic virus type 1 (HTLV-1) in Guinea-Bissau is largely unknown; vertical transmission is thought to be important, but there are very few existing data. We aimed to examine factors associated with transmission in mothers and
Christoph J Burckhardt
Full Text Available How viruses are transmitted across the mucosal epithelia of the respiratory, digestive, or excretory tracts, and how they spread from cell to cell and cause systemic infections, is incompletely understood. Recent advances from single virus tracking experiments have revealed conserved patterns of virus movements on the plasma membrane, including diffusive motions, drifting motions depending on retrograde flow of actin filaments or actin tail formation by polymerization, and confinement to submicrometer areas. Here, we discuss how viruses take advantage of cellular mechanisms that normally drive the movements of proteins and lipids on the cell surface. A concept emerges where short periods of fast diffusive motions allow viruses to rapidly move over several micrometers. Coupling to actin flow supports directional transport of virus particles during entry and cell-cell transmission, and local confinement coincides with either nonproductive stalling or infectious endocytic uptake. These conserved features of virus-host interactions upstream of infectious entry offer new perspectives for anti-viral interference.
Bertran, Kateri; Balzli, Charles; Kwon, Yong-Kuk; Tumpey, Terrence M; Clark, Andrew; Swayne, David E
Exposure to infected poultry is a suspected cause of avian influenza (H5N1) virus infections in humans. We detected infectious droplets and aerosols during laboratory-simulated processing of asymptomatic chickens infected with human- (clades 1 and 2.2.1) and avian- (clades 1.1, 2.2, and 2.1) origin H5N1 viruses. We detected fewer airborne infectious particles in simulated processing of infected ducks. Influenza virus-naive chickens and ferrets exposed to the air space in which virus-infected chickens were processed became infected and died, suggesting that the slaughter of infected chickens is an efficient source of airborne virus that can infect birds and mammals. We did not detect consistent infections in ducks and ferrets exposed to the air space in which virus-infected ducks were processed. Our results support the hypothesis that airborne transmission of HPAI viruses can occur among poultry and from poultry to humans during home or live-poultry market slaughter of infected poultry.
Le Goff, G.; Revollo, J.; Guerra, M.; Cruz, M.; Barja Simon, Z.; Roca, Y.; Vargas Florès, J.; Hervé, J.P.
The natural transmission of dengue virus from an infected female mosquito to its progeny, namely the vertical transmission, was researched in wild caught Aedes aegypti during an important outbreak in the town of Santa Cruz de la Sierra, Bolivia. Mosquitoes were collected at the preimaginal stages (eggs, larvae and pupae) then reared up to adult stage for viral detection using molecular methods. Dengue virus serotypes 1 and 3 were found to be co-circulating with significant higher prevalence in male than in female mosquitoes. Of the 97 pools of Ae. aegypti (n = 635 male and 748 female specimens) screened, 14 pools, collected in February-May in 2007, were found positive for dengue virus infection: five DEN-1 and nine DEN-3. The average true infection rate (TIR) and minimum infection rate (MIR) were respectively 1.08% and 1.01%. These observations suggest that vertical transmission of dengue virus may be detected in vectors at the peak of an outbreak as well as several months before an epidemic occurs in human population. PMID:21894270
Full Text Available Dengue virus (DENV infection of an individual human or mosquito host produces a dynamic population of closely-related sequences. This intra-host genetic diversity is thought to offer an advantage for arboviruses to adapt as they cycle between two very different host species, but it remains poorly characterized. To track changes in viral intra-host genetic diversity during horizontal transmission, we infected Aedes aegypti mosquitoes by allowing them to feed on DENV2-infected patients. We then performed whole-genome deep-sequencing of human- and matched mosquito-derived DENV samples on the Illumina platform and used a sensitive variant-caller to detect single nucleotide variants (SNVs within each sample. >90% of SNVs were lost upon transition from human to mosquito, as well as from mosquito abdomen to salivary glands. Levels of viral diversity were maintained, however, by the regeneration of new SNVs at each stage of transmission. We further show that SNVs maintained across transmission stages were transmitted as a unit of two at maximum, suggesting the presence of numerous variant genomes carrying only one or two SNVs each. We also present evidence for differences in selection pressures between human and mosquito hosts, particularly on the structural and NS1 genes. This analysis provides insights into how population drops during transmission shape RNA virus genetic diversity, has direct implications for virus evolution, and illustrates the value of high-coverage, whole-genome next-generation sequencing for understanding viral intra-host genetic diversity.
Amari, Khalid; Burgos, Lorenzo; Pallás, Vicente; Sánchez-Pina, Maria Amelia
The aim of this work was to follow Prunus necrotic ringspot virus (PNRSV) infection in apricot reproductive tissues and transmission of the virus to the next generation. For this, an analysis of viral distribution in apricot reproductive organs was carried out at different developmental stages. PNRSV was detected in reproductive tissues during gametogenesis. The virus was always present in the nucellus and, in some cases, in the embryo sac. Studies within infected seeds at the embryo globular stage revealed that PNRSV infects all parts of the seed, including embryo, endosperm and testa. In the torpedo and bent cotyledon developmental stages, high concentrations of the virus were detected in the testa and endosperm. At seed maturity, PNRSV accumulated slightly more in the embryo than in the cotyledons. In situ hybridization showed the presence of PNRSV RNA in embryos obtained following hand-pollination of virus-free pistils with infected pollen. Interestingly, tissue-printing from fruits obtained from these pistils showed viral RNA in the periphery of the fruits, whereas crosses between infected pistils and infected pollen resulted in a total invasion of the fruits. Taken together, these results shed light on the vertical transmission of PNRSV from gametes to seedlings.
Patterson Ross, Zoe; Komadina, Naomi; Deng, Yi-Mo; Spirason, Natalie; Kelly, Heath A.; Sullivan, Sheena G.; Barr, Ian G.; Holmes, Edward C.
The factors that determine the characteristic seasonality of influenza remain enigmatic. Current models predict that occurrences of influenza outside the normal surveillance season within a temperate region largely reflect the importation of viruses from the alternate hemisphere or from equatorial regions in Asia. To help reveal the drivers of seasonality we investigated the origins and evolution of influenza viruses sampled during inter-seasonal periods in Australia. To this end we conducted an expansive phylogenetic analysis of 9912, 3804, and 3941 hemagglutinnin (HA) sequences from influenza A/H1N1pdm, A/H3N2, and B, respectively, collected globally during the period 2009-2014. Of the 1475 viruses sampled from Australia, 396 (26.8% of Australian, or 2.2% of global set) were sampled outside the monitored temperate influenza surveillance season (1 May – 31 October). Notably, rather than simply reflecting short-lived importations of virus from global localities with higher influenza prevalence, we documented a variety of more complex inter-seasonal transmission patterns including “stragglers” from the preceding season and “heralds” of the forthcoming season, and which included viruses sampled from clearly temperate regions within Australia. We also provide evidence for the persistence of influenza B virus between epidemic seasons, in which transmission of a viral lineage begins in one season and continues throughout the inter-seasonal period into the following season. Strikingly, a disproportionately high number of inter-seasonal influenza transmission events occurred in tropical and subtropical regions of Australia, providing further evidence that climate plays an important role in shaping patterns of influenza seasonality. PMID:26107631
Mammen, Mammen P; Pimgate, Chusak; Koenraadt, Constantianus J M; Rothman, Alan L; Aldstadt, Jared; Nisalak, Ananda; Jarman, Richard G; Jones, James W; Srikiatkhachorn, Anon; Ypil-Butac, Charity Ann; Getis, Arthur; Thammapalo, Suwich; Morrison, Amy C; Libraty, Daniel H; Green, Sharone; Scott, Thomas W
Transmission of dengue viruses (DENV), the leading cause of arboviral disease worldwide, is known to vary through time and space, likely owing to a combination of factors related to the human host, virus, mosquito vector, and environment. An improved understanding of variation in transmission patterns is fundamental to conducting surveillance and implementing disease prevention strategies. To test the hypothesis that DENV transmission is spatially and temporally focal, we compared geographic and temporal characteristics within Thai villages where DENV are and are not being actively transmitted. Cluster investigations were conducted within 100 m of homes where febrile index children with (positive clusters) and without (negative clusters) acute dengue lived during two seasons of peak DENV transmission. Data on human infection and mosquito infection/density were examined to precisely (1) define the spatial and temporal dimensions of DENV transmission, (2) correlate these factors with variation in DENV transmission, and (3) determine the burden of inapparent and symptomatic infections. Among 556 village children enrolled as neighbors of 12 dengue-positive and 22 dengue-negative index cases, all 27 DENV infections (4.9% of enrollees) occurred in positive clusters (p availability of piped water in negative clusters (p < 0.01) and greater number of Ae. aegypti pupae per person in positive clusters (p = 0.04). During primarily DENV-4 transmission seasons, the ratio of inapparent to symptomatic infections was nearly 1:1 among child enrollees. Study limitations included inability to sample all children and mosquitoes within each cluster and our reliance on serologic rather than virologic evidence of interval infections in enrollees given restrictions on the frequency of blood collections in children. Our data reveal the remarkably focal nature of DENV transmission within a hyperendemic rural area of Thailand. These data suggest that active school-based dengue case detection
Full Text Available The aim of this study was to assess the mechanisms of transmission of bluetongue virus serotype 26 (BTV-26 in goats. A previous study, which investigated the pathogenicity and infection kinetics of BTV-26 in goats, unexpectedly revealed that one control goat may have been infected through a direct contact transmission route. To investigate the transmission mechanisms of BTV-26 in more detail an experimental infection study was carried out in which three goats were infected with BTV-26, three goats were kept uninfected, but were housed in direct contact with the infected goats, and an additional four goats were kept in indirect contact separated from infected goats by metal gates. This barrier allowed the goats to have occasional face-to-face contact in the same airspace, but feeding, watering, sampling and environmental cleaning was carried out separately. The three experimentally infected goats did not show clinical signs of BTV, however high levels of viral RNA were detected and virus was isolated from their blood. At 21 dpi viral RNA was detected in, and virus was isolated from the blood of the three direct contact goats, which also seroconverted. The four indirect barrier contact goats remained uninfected throughout the duration of the experiment. In order to assess replication in a laboratory model species of Culicoides biting midge, more than 300 Culicoides sonorensis were fed a BTV-26 spiked blood meal and incubated for 7 days. The dissemination of BTV-26 in individual C. sonorensis was inferred from the quantity of virus RNA and indicated that none of the insects processed at day 7 possessed transmissible infections. This study shows that BTV-26 is easily transmitted through direct contact transmission between goats, and the strain does not seem to replicate in C. sonorensis midges using standard incubation conditions.
Liu, Danfeng; Li, Pei; Han, Yongqiang; Lei, Wenbin; Hou, Maolin
Southern rice black-streaked dwarf virus (SRBSDV) is a novel virus transmitted by white-backed planthopper Sogatella furcifera (Hováth) (Hemiptera: Delphacidae). Due to low virus transmission efficiency by the planthopper, researchers are frequently confronted with shortage of viruliferous vectors or infected rice plants, especially in winter and the following spring. To find new ways to maintain virus-infected materials, viral rice plants were stored at -80°C for 45 or 140 d and evaluated as virus sources in virus transmission by the vector. SRBSDV virions were not degraded during storage at -80°C as indicated by reverse transcription-polymerase chain reaction and reverse transcription real-time PCR detection. The planthopper nymphs fed on the infected thawed plants for 48 h survived at about 40% and showed positive detection of SRBSDV, but they lost the virus after feeding for another 20 d (the circulative transmission period) on noninfected plants. Transmission electron microscope images indicated broken capsid of virions in infected thawed leaves in contrast to integrity capsid of virions in infected fresh leaves. These results show that low temperature storage of SRBSDV-infected rice plants cannot sustain virus transmission by white-backed planthopper. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: firstname.lastname@example.org.
Hayashi, Kazuhiko; Katano, Yoshiaki; Chuong, Tran Xuan; Takeda, Yasushi; Ishigami, Masatoshi; Itoh, Akihiro; Hirooka, Yoshiki; Nakano, Isao; Huy, Tran Van; Minh, Nguyen Ngoc; Diem, Tran thi Minh; An, Dong thi Hoai; Phiet, Pham Hoang; Goto, Hidemi
Hepatitis B virus (HBV) has been classified into 8 genotypes that have different geographic distributions. The clinical outcomes of acute hepatitis are dependent on genotype. The aim of this study was to investigate the distribution of HBV subgenotypes and basal core promoter (BCP)/precore (PC) regions in acute hepatitis patients in Central Vietnam to clarify the distributions and the clinical and virological differences. 27 patients with acute hepatitis B were studied. HBV subgenotypes and BCP/PC variants were determined by direct sequencing of the preS, BCP/PC regions, respectively. HBV subgenotypes B4/Ba (n = 22) and C1/Cs (n = 5) were detected. Of the 27 patients, 3 developed fulminant hepatic failure, and all were infected with B4/Ba. Three patients had a BCP mutation, and 10 patients had a PC mutation in subgenotype B4/Ba. Three patients with C1/Cs had a BCP mutation. Two of 3 patients who progressed to fulminant hepatic failure had T1762, A1764, and A1896 simultaneously. None of the patients with acute, self-limited hepatitis carried these triple mutations. The prevalent HBV subgenotypes in patients with acute hepatitis B in Central Vietnam were B4/Ba and C1/Cs. BCP/PC variants have an association with the development of fulminant hepatic failure in subgenotype B4/Ba. Copyright 2009 S. Karger AG, Basel.
Hammett, Theodore M; Wu, Zunyou; Duc, Tran Tien; Stephens, David; Sullivan, Sheena; Liu, Wei; Chen, Yi; Ngu, Doan; Des Jarlais, Don C
This paper reviews the evolution of government policies in China and Vietnam regarding harm reduction interventions for human immunodeficiency virus (HIV) prevention, such as needle/syringe provision and opioid substitution treatment. The work is based upon the authors' experiences in and observations of these policy developments, as well as relevant government policy documents and legislation. Both countries are experiencing HIV epidemics driven by injection drug use and have maintained generally severe policies towards injection drug users (IDUs). In recent years, however, they have also officially endorsed harm reduction. We sought to understand how and why this apparently surprising policy evolution took place. Factors associated with growing support for harm reduction were similar but not identical in China and Vietnam. These included the emergence of effective 'champions' for such policies, an ethos of pragmatism and receptivity to evidence, growing collaboration across public health, police and other sectors, the influence of contingent events such as the severe acute respiratory syndrome (SARS) epidemic and pressure from donors and international organizations to adopt best practice in HIV prevention. Ongoing challenges and lessons learned include the persistence of tensions between drug control and harm reduction that may have negative effects on programs until a fully harmonized policy environment is established. Excessive reliance on law enforcement and forced detoxification will not solve the problems of substance abuse or of HIV among drug users. Ongoing evaluation of harm reduction programs, as well as increased levels of multi-sectoral training, collaboration and support are also needed.
A study of the viral samples collected in French natural populations of Drosophila melanogaster since 1969, indicates that natural populations include, as expected, both stabilized and non stabilized infected individuals. In agreement with previous observations made on other characters of the virus, the viral samples collected appear to be homogeneous for the efficiency of the hereditary transmission. However, this efficiency is greater than the average value observed with virus perpetuated in infected laboratory fly strains. One sample collected in Gabon and three in the U.S.A. appear to differ from the French samples for one at least of the traits studied in these experiments.
Secundino, Nagila Francinete Costa; Chaves, Barbara Aparecida; Orfano, Alessandra Silva; Silveira, Karine Renata Dias; Rodrigues, Nilton Barnabe; Campolina, Thais Bonifácio; Nacif-Pimenta, Rafael; Villegas, Luiz Eduardo Martinez; Silva, Breno Melo; Lacerda, Marcus Vinícius Guimarães; Norris, Douglas Eric; Pimenta, Paulo Filemon Paolucci
Zika disease has transformed into a serious global health problem due to the rapid spread of the arbovirus and alarming severity including congenital complications, microcephaly and Guillain-Barré syndrome. Zika virus (ZIKV) is primarily transmitted to humans through the bite of an infective mosquito, with Aedes aegypti being the main vector. We successfully developed a ZIKV experimental transmission model by single infectious Ae. aegypti bite to a laboratory mouse using circulating Brazilian strains of both arbovirus and vector. Mosquitoes were orally infected and single Ae. aegypti were allowed to feed on mouse ears 14 days post-infection. Additionally, salivary gland (SG) homogenates from infected mosquitoes were intrathoracically inoculated into naïve Ae. aegypti. Mosquito and mouse tissue samples were cultured in C6/36 cells and processed by quantitative real-time PCR. A total of 26 Ae. aegypti were allowed to feed individually on mouse ears. Of these, 17 mosquitoes fed, all to full engorgement. The transmission rate of ZIKV by bite from these engorged mosquitoes to mouse ears was 100%. The amount of virus inoculated into the ears by bites ranged from 2 × 10 2 -2.1 × 10 10 ZIKV cDNA copies and was positively correlated with ZIKV cDNA quantified from SGs dissected from mosquitoes post-feeding. Replicating ZIKV was confirmed in macerated SGs (2.45 × 10 7 cDNA copies), mouse ear tissue (1.15 × 10 3 cDNA copies, and mosquitoes 14 days post-intrathoracic inoculation (1.49 × 10 7 cDNA copies) by cytopathic effect in C6/36 cell culture and qPCR. Our model illustrates successful transmission of ZIKV by an infectious mosquito bite to a live vertebrate host. This approach offers a comprehensive tool for evaluating the development of infection in and transmission from mosquitoes, and the vertebrate-ZIKV interaction and progression of infection following a natural transmission process.
Vyas, Ashish Kumar; Ramakrishna, Usha; Sen, Bijoya; Islam, Mojahidul; Ramakrishna, Gayatri; Patra, Sharda; Rastogi, Archana; Sarin, Shiv Kumar; Trehanpati, Nirupma
Asialoglycoprotein receptor expression on hepatocytes has been associated with endocytosis, binding and uptake of hepatitis B virus. The role of asialoglycoprotein receptor in hepatitis B virus vertical transmission and its expression on placenta has not yet been studied. Thirty-four HBsAg+ve and 13 healthy pregnant mothers along with their newborns were enrolled. The former were categorized into transmitting and non-transmitting mothers based on their newborns being hepatitis B surface antigen and hepatitis B virus DNA positive. Expression of asialoglycoprotein receptor and hepatitis B surface antigen in placenta and isoform of asialoglycoprotein receptor on dendritic cell in peripheral and cord blood dendritic cells were analysed using flowcytometry, immune histochemistry, immune florescence and qRT-PCR. Twelve HBsAg+ve mothers transmitted hepatitis B virus to their newborns whereas the rest (n = 22) did not. Hepatitis B virus-transmitting mothers showed increased expression of asialoglycoprotein receptor in trophoblasts of placenta. Immunofluorescence microscopy revealed colocalization of hepatitis B surface antigen and asialoglycoprotein receptor in placenta as well as in DCs of transmitting mothers. There was no significant difference in the expression of asialoglycoprotein receptor on peripheral blood mononuclear cells or chord blood mononuclear cells between the 2 groups. However, hepatitis B virus-transmitting mothers and their HBsAg+ve newborns showed increased mRNA levels of isoform of asialoglycoprotein receptor on dendritic cell in peripheral blood mononuclear cells. Hepatitis B virus-transmitting mothers and their HBsAg+ve newborns showed an increased expression of isoform of asialoglycoprotein receptor on dendritic cell on circulating dendritic cells compared to hepatitis B virus non-transmitting mothers and their negative newborns. This study revealed that increased expression of asialoglycoprotein receptor in placenta and colocalization with
Atrasheuskaya, A V; Neverov, A A; Rubin, S; Ignatyev, G M
Here we describe symptomatic transmission of the Leningrad-3 mumps vaccine virus from healthy vaccinees to previously vaccinated contacts. Throat swab and serum samples were taken from six symptomatic mumps cases and from 13 family contacts. Assessment of serum IgG and IgM anti-mumps virus antibodies and IgG avidity testing was performed using commercial test kits. Sera neutralizing antibodies were measured by plaque reduction neutralization assay using the L-3 vaccine mumps virus as the target. All six of the symptomatic mumps cases and three contact subjects tested positive for mumps by RT-PCR. The genomic sequences tested (F, SH and HN genes) of all nine of these samples were identical to the L-3 mumps vaccine strain. All 13 contacts were asymptomatic; however clear serological evidence of mumps infection was found in some of them. The likely epidemiological source of the transmitted L-3 mumps virus was children who were recently vaccinated at the schools attended by the six symptomatic mumps patients described here. The L-3 mumps vaccine virus can be shed and transmitted horizontally, even to subjects previously vaccinated with the same virus.
Ito, Eisuke; Sato, Takaaki; Sano, Daisuke; Utagawa, Etsuko; Kato, Tsuyoshi
A new computational method for the detection of virus particles in transmission electron microscopy (TEM) images is presented. Our approach is to use a convolutional neural network that transforms a TEM image to a probabilistic map that indicates where virus particles exist in the image. Our proposed approach automatically and simultaneously learns both discriminative features and classifier for virus particle detection by machine learning, in contrast to existing methods that are based on handcrafted features that yield many false positives and require several postprocessing steps. The detection performance of the proposed method was assessed against a dataset of TEM images containing feline calicivirus particles and compared with several existing detection methods, and the state-of-the-art performance of the developed method for detecting virus was demonstrated. Since our method is based on supervised learning that requires both the input images and their corresponding annotations, it is basically used for detection of already-known viruses. However, the method is highly flexible, and the convolutional networks can adapt themselves to any virus particles by learning automatically from an annotated dataset.
Nolting, J M; Midla, J; Whittington, M S; Scheer, S D; Bowman, A S
Influenza A virus (IAV) is a major zoonotic pathogen that threatens global public health. Novel strains of influenza A viruses pose a significant risk to public health due to their pandemic potential, and transmission of influenza A viruses from animals to humans is an important mechanism in the generation and introduction of IAVs that threaten human health. The purpose of this descriptive correlational study was to develop real-life training scenarios to better inform swine exhibitors of the risks they may encounter when influenza A viruses are present in swine. Educational activities were implemented in five Ohio counties where exhibition swine had historically been shedding influenza A viruses during the county fair. A total of 146 youth swine exhibitors participated in the educational programme, and an increase in the knowledge base of these youth was documented. It is expected that educating youth exhibitors about exposure to influenza A virus infections in the swine they are exhibiting will result in altered behaviours and animal husbandry practices that will improve both human and animal health. © 2017 Blackwell Verlag GmbH.
Sy, Bui Tien; Ratsch, Boris A.; Toan, Nguyen Linh; Song, Le Huu; Wollboldt, Christian; Bryniok, Agnes; Nguyen, Hung Minh; Luong, Hoang Van; Velavan, Thirumalaisamy P.; Wedemeyer, Heiner; Kremsner, Peter G.; Bock, C.-Thomas
Background Hepatitis D virus (HDV) infection is considered to cause more severe hepatitis than hepatitis B virus (HBV) monoinfection. With more than 9.5 million HBV-infected people, Vietnam will face an enormous health burden. The prevalence of HDV in Vietnamese HBsAg-positive patients is speculative. Therefore, we assessed the prevalence of HDV in Vietnamese patients, determined the HDV-genotype distribution and compared the findings with the clinical outcome. Methods 266 sera of well-characterized HBsAg-positive patients in Northern Vietnam were analysed for the presence of HDV using newly developed HDV-specific RT-PCRs. Sequencing and phylogenetic analysis were performed for HDV-genotyping. Results The HDV-genome prevalence observed in the Vietnamese HBsAg-positive patients was high with 15.4% while patients with acute hepatitis showed 43.3%. Phylogenetic analysis demonstrated a predominance of HDV-genotype 1 clustering in an Asian clade while HDV-genotype 2 could be also detected. The serum aminotransferase levels (AST, ALT) as well as total and direct bilirubin were significantly elevated in HDV-positive individuals (p<0.05). HDV loads were mainly low (<300 to 4.108 HDV-copies/ml). Of note, higher HDV loads were mainly found in HBV-genotype mix samples in contrast to single HBV-infections. In HBV/HDV-coinfections, HBV loads were significantly higher in HBV-genotype C in comparison to HBV-genotype A samples (p<0.05). Conclusion HDV prevalence is high in Vietnamese individuals, especially in patients with acute hepatitis B. HDV replication activity showed a HBV-genotype dependency and could be associated with elevated liver parameters. Besides serological assays molecular tests are recommended for diagnosis of HDV. Finally, the high prevalence of HBV and HDV prompts the urgent need for HBV-vaccination coverage. PMID:24205106
Full Text Available Human T-cell lymphotropic virus type 1 (HTLV-1 is endemic in many parts of the world and is primarily transmitted through sexual intercourse or from mother to child. Sexual transmission occurs more efficiently from men to women than women to men and might be enhanced by sexually transmitted diseases that cause ulcers and result in mucosal ruptures, such as syphilis, herpes simplex type 2 (HSV-2, and chancroid. Other sexually transmitted diseases might result in the recruitment of inflammatory cells and could increase the risk of HTLV-1 acquisition and transmission. Additionally, factors that are associated with higher transmission risks include the presence of antibodies against the viral oncoprotein Tax (anti-Tax, a higher proviral load in peripheral blood lymphocytes, and increased cervicovaginal or seminal secretions. Seminal fluid has been reported to increase HTLV replication and transmission, whereas male circumcision and neutralizing antibodies might have a protective effect. Recently, free virions were discovered in plasma, which reveals a possible new mode of HTLV replication. It is unclear how this discovery might affect the routes of HTLV transmission, particularly sexual transmission, because HTLV transmission rates are significantly higher from men to women than women to men.
Damien C Tully
Full Text Available Due to the stringent population bottleneck that occurs during sexual HIV-1 transmission, systemic infection is typically established by a limited number of founder viruses. Elucidation of the precise forces influencing the selection of founder viruses may reveal key vulnerabilities that could aid in the development of a vaccine or other clinical interventions. Here, we utilize deep sequencing data and apply a genetic distance-based method to investigate whether the mode of sexual transmission shapes the nascent founder viral genome. Analysis of 74 acute and early HIV-1 infected subjects revealed that 83% of men who have sex with men (MSM exhibit a single founder virus, levels similar to those previously observed in heterosexual (HSX transmission. In a metadata analysis of a total of 354 subjects, including HSX, MSM and injecting drug users (IDU, we also observed no significant differences in the frequency of single founder virus infections between HSX and MSM transmissions. However, comparison of HIV-1 envelope sequences revealed that HSX founder viruses exhibited a greater number of codon sites under positive selection, as well as stronger transmission indices possibly reflective of higher fitness variants. Moreover, specific genetic "signatures" within MSM and HSX founder viruses were identified, with single polymorphisms within gp41 enriched among HSX viruses while more complex patterns, including clustered polymorphisms surrounding the CD4 binding site, were enriched in MSM viruses. While our findings do not support an influence of the mode of sexual transmission on the number of founder viruses, they do demonstrate that there are marked differences in the selection bottleneck that can significantly shape their genetic composition. This study illustrates the complex dynamics of the transmission bottleneck and reveals that distinct genetic bottleneck processes exist dependent upon the mode of HIV-1 transmission.
Full Text Available The spike proteins of a number of coronaviruses are able to bind to sialic acids present on the cell surface. The importance of this sialic acid binding ability during infection is, however, quite different. We compared the spike protein of transmissible gastroenteritis virus (TGEV and the spike protein of infectious bronchitis virus (IBV. Whereas sialic acid is the only receptor determinant known so far for IBV, TGEV requires interaction with its receptor aminopeptidase N to initiate infection of cells. Binding tests with soluble spike proteins carrying an IgG Fc-tag revealed pronounced differences between these two viral proteins. Binding of the IBV spike protein to host cells was in all experiments sialic acid dependent, whereas the soluble TGEV spike showed binding to APN but had no detectable sialic acid binding activity. Our results underline the different ways in which binding to sialoglycoconjugates is mediated by coronavirus spike proteins.
González-Candelas, Fernando; Guiral, Silvia; Carbó, Rosa; Valero, Ana; Vanaclocha, Hermelinda; González, Francisco; Bracho, Maria Alma
No recognized risk factors can be identified in 10-40% of hepatitis C virus (HCV)-infected patients suggesting that the modes of transmission involved could be underestimated or unidentified. Invasive diagnostic procedures, such as endoscopy, have been considered as a potential HCV transmission route; although the actual extent of transmission in endoscopy procedures remains controversial. Most reported HCV outbreaks related to nosocomial acquisition have been attributed to unsafe injection practices and use of multi-dose vials. Only a few cases of likely patient-to-patient HCV transmission via a contaminated colonoscope have been reported to date. Nosocomial HCV infection may have important medical and legal implications and, therefore, possible transmission routes should be investigated. In this study, a case of nosocomial transmission of HCV from a common source to two patients who underwent colonoscopy in an endoscopy unit is reported. A retrospective epidemiological search after detection of index cases revealed several potentially infective procedures: sample blood collection, use of a peripheral catheter, anesthesia and colonoscopy procedures. The epidemiological investigation showed breaches in colonoscope reprocessing and deficiencies in the recording of valuable tracing data. Direct sequences from the NS5B region were obtained to determine the extent of the outbreak and cloned sequences from the E1-E2 region were used to establish the relationships among intrapatient viral populations. Phylogenetic analyses of individual sequences from viral populations infecting the three patients involved in the outbreak confirmed the patient pointed out by the epidemiological search as the source of the outbreak. Furthermore, the sequential order in which the patients underwent colonoscopy correlates with viral genetic variability estimates. Patient-to-patient transmission of HCV could be demonstrated although the precise route of transmission remained unclear. Viral
Benjamin D Dalziel
Full Text Available Host-range shifts in influenza virus are a major risk factor for pandemics. A key question in the study of emerging zoonoses is how the evolution of transmission efficiency interacts with heterogeneity in contact patterns in the new host species, as this interplay influences disease dynamics and prospects for control. Here we use a synergistic mixture of models and data to tease apart the evolutionary and demographic processes controlling a host-range shift in equine H3N8-derived canine influenza virus (CIV. CIV has experienced 15 years of continuous transfer among dogs in the United States, but maintains a patchy distribution, characterized by sporadic short-lived outbreaks coupled with endemic hotspots in large animal shelters. We show that CIV has a high reproductive potential in these facilities (mean R(0 = 3.9 and that these hotspots act as refugia from the sparsely connected majority of the dog population. Intriguingly, CIV has evolved a transmission efficiency that closely matches the minimum required to persist in these refugia, leaving it poised on the extinction/invasion threshold of the host contact network. Corresponding phylogenetic analyses show strong geographic clustering in three US regions, and that the effective reproductive number of the virus (R(e in the general dog population is close to 1.0. Our results highlight the critical role of host contact structure in CIV dynamics, and show how host contact networks could shape the evolution of pathogen transmission efficiency. Importantly, efficient control measures could eradicate the virus, in turn minimizing the risk of future sustained transmission among companion dogs that could represent a potential new axis to the human-animal interface for influenza.
Scott C. Weaver
ABSTRACT The mechanisms responsible for the dramatic emergence of Zika virus (ZIKV), accompanied by congenital Zika syndrome and Guillain-Barr? syndrome (GBS), remain unclear. However, two hypotheses are prominent: (i) evolution for enhanced urban transmission via adaptation to mosquito vectors, or for enhanced human infection to increase amplification, or (ii) the stochastic introduction of ZIKV into large, naive human populations in regions with abundant Aedes aegypti populations, leading t...
Hartemink, N. A.; Davis, S. A.; Reiter, P.; Hubálek, Zdeněk; Heesterbeek, J. A. P.
Roč. 7, č. 4 (2007), s. 575-584 ISSN 1530-3667 EU Projects: European Commission(XE) 10284 - EDEN Institutional research plan: CEZ:AV0Z60930519 Source of funding: R - rámcový projekt EK Keywords : West Nile virus * basic reproduction number * direct transmission Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 1.919, year: 2007
Olesen, Ann Sofie; Lohse, Louise; Boklund, Anette
from Poland (designated here POL/2015/Podlaskie/Lindholm). In both studies, pigs were inoculated intranasally with the virus and contact pigs were exposed to the experimentally infected pigs, either directly (contact within and between pens) or by air. Pigs exposed to the virus by intranasal...... and occasionally infectious virus was found in nasal-, oral-, and rectal swabs obtained from the pigs, and ASFV DNA was detected in air samples. No anti-ASFV antibodies were detected in sera.In conclusion, the study shows that the currently circulating strain of ASFV can be efficiently transmitted via direct...... contact and by aerosols. Also, the results provide quantitative transmission parameters and knowledge of infection stages in pigs infected with this ASFV....
Porcine epidemic diarrhea virus (PEDV) emerged in the U.S. in April 2013 and caused significant losses to the swine industry. The purpose of this investigation was to determine tissue localization, shedding patterns, virus carriage, antibody response, and aerosol transmission of PEDV following inocu...
Maryland State Dept. of Health and Mental Hygiene, Baltimore.
This Maryland resource manual provides local education agencies with guidelines on how to handle body fluids to prevent the transmission of diseases, especially Human Immunodeficiency Virus (HIV) and Hepatitis B Virus (HBV), in the school setting. The first section summarizes the reasons for development of the manual. The second section summarizes…
Maryland State Dept. of Health and Mental Hygiene, Baltimore.
Guidelines to prevent the transmission of blood-borne diseases, especially those caused by the Human Immunodeficiency Virus (HIV) and the Hepatitis B Virus (HBV), in the school setting are provided in this resource manual for school staff. Sections include information on the reasons for the development of this manual; a summary of the means of HIV…
Vanhommerig, Joost W.; Lambers, Femke A. E.; Schinkel, Janke; Geskus, Ronald B.; Arends, Joop E.; van de Laar, Thijs J. W.; Lauw, Fanny N.; Brinkman, Kees; Gras, Luuk; Rijnders, Bart J. A.; van der Meer, Jan T. M.; Prins, Maria; Molenkamp, R.; Mutschelknauss, M.; Nobel, H. E.; Reesink, H. W.; van der Valk, M.; van den Berk, G. E. L.; Brinkman, K.; Kwa, D.; van der Meche, N.; Toonen, A.; Vos, D.; van Broekhuizen, M.; Lauw, F. N.; Mulder, J. W.; Arends, J. E.; van Kessel, A.; de Kroon, I.; Boonstra, A.; van der Ende, M. E.; Hullegie, S.; Rijnders, B. J. A.; van de laar, T. J. W.; Gras, L.; Smit, C.; van der Veldt, W.
Background. Since 2000, incidence of sexually acquired hepatitis C virus (HCV)-infection has increased among human immunodeficiency virus (HIV)-infected men who have sex with men (MSM). To date, few case-control and cohort studies evaluating HCV transmission risk factors were conducted in this
van de Laar, Thijs J. W.; Paxton, William A.; Zorgdrager, Fokla; Cornelissen, Marion; de Vries, Henry J. C.
Hepatitis C Virus (HCV) has recently emerged as sexual transmitted infection among (human immunodeficiency virus) HIV-positive but not HIV-negative men who have sex with men (MSM). We present 4 case reports showing that HIV-infection is not an absolute prerequisite for sexual HCV transmission in
Full Text Available Abstract Background In Thailand, rabies remains a neglected disease with authorities continuing to rely on human death statistics while ignoring the financial burden resulting from an enormous increase in post-exposure prophylaxis. Past attempts to conduct a mass dog vaccination and sterilization program have been limited to Bangkok city and have not been successful. We have used molecular epidemiology to define geographic localization of rabies virus phylogroups and their pattern of spread in Thailand. Methods We analyzed 239 nucleoprotein gene sequences from animal and human brain samples collected from all over Thailand between 1998 and 2002. We then reconstructed a phylogenetic tree correlating these data with geographical information. Results All sequences formed a monophyletic tree of 2 distinct phylogroups, TH1 and TH2. Three subgroups were identified in the TH1 subgroup and were distributed in the middle region of the country. Eight subgroups of TH2 viruses were identified widely distributed throughout the country overlapping the TH1 territory. There was a correlation between human-dependent transportation routes and the distribution of virus. Conclusion Inter-regional migration paths of the viruses might be correlated with translocation of dogs associated with humans. Interconnecting factors between human socioeconomic and population density might determine the transmission dynamics of virus in a rural-to-urban polarity. The presence of 2 or more rabies virus groups in a location might be indicative of a gene flow, reflecting a translocation of dogs within such region and adjacent areas. Different approaches may be required for rabies control based on the homo- or heterogeneity of the virus. Areas containing homogeneous virus populations should be targeted first. Control of dog movement associated with humans is essential.
Day, Jonathan F; Tabachnick, Walter J; Smartt, Chelsea T
West Nile virus (WNV) was first detected in North America in New York City during the late summer of 1999 and was first detected in Florida in 2001. Although WNV has been responsible for widespread and extensive epidemics in human populations and epizootics in domestic animals and wildlife throughout North America, comparable epidemics have never materialized in Florida. Here, we review some of the reasons why WNV has yet to cause an extensive outbreak in Florida. The primary vector of mosquito-borne encephalitis virus in Florida is Culex nigripalpus Theobald. Rainfall, drought, and temperature are the primary factors that regulate annual populations of this species. Cx. nigripalpus is a competent vector of WNV, St. Louis encephalitis virus, and eastern equine encephalitis virus in Florida, and populations of this species can support focal amplification and transmission of these arboviruses. We propose that a combination of environmental factors influencing Cx. nigripalpus oviposition, blood-feeding behavior, and vector competence have limited WNV transmission in Florida to relatively small focal outbreaks and kept the state free of a major epidemic. Florida must remain vigilant to the danger from WNV, because a change in these environmental factors could easily result in a substantial WNV epidemic rivaling those seen elsewhere in the United States. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: email@example.com.
The Epidemiology, Clinical Characteristic,Transmission Potential and Control Measures of Zika Virus Infection%The Epidemiology,Clinical Characteristic,Transmission Potential and Control Measures of Zika Virus Infection
ALOTAIBIABDULLAHSAUDM; ALANAZIMANSOURRASHEDM; AHMADMEESAQ
Zika virus (ZIKV) is an emerging mosquito born positive standard RNA arbovirus of Flaviviriadae family.Zika virus has been identified sporadically in human in Africa and Asia;however,clinically consequential Zika virus disease had not been documented before to the recent outbreak in the America in 2015.It is rapidly spread across the America and its devastating outcomes for pregnant women and infants.Prior to outbreak of America,Zika virus outbreaks occurred in Yap Island in Micronesia in 2007 and in French Polynesia in 2013.The World Health Organisation (WHO) declarer a Public Health Emergency of International Concern on February 1,2016.Because of the continuous geographicexpansion of both the virus and its mosquito vectors,ZIKV poses a serious threat to public health aroundthe globe.This review summarizes a fast growing body of literature on the history,epidemiology,transmission,clinical presentation and control measures to prevent the transmission of Zika virus.
Belser, Jessica A; Blixt, Ola; Chen, Li-Mei
Avian H7 influenza viruses from both the Eurasian and North American lineage have caused outbreaks in poultry since 2002, with confirmed human infection occurring during outbreaks in The Netherlands, British Columbia, and the United Kingdom. The majority of H7 infections have resulted in self-lim...
Rory D de Vries
Full Text Available Identification of cellular receptors and characterization of viral tropism in animal models have vastly improved our understanding of morbillivirus pathogenesis. However, specific aspects of viral entry, dissemination and transmission remain difficult to recapitulate in animal models. Here, we used three virologically identical but phenotypically distinct recombinant (r canine distemper viruses (CDV expressing different fluorescent reporter proteins for in vivo competition and airborne transmission studies in ferrets (Mustela putorius furo. Six donor ferrets simultaneously received three rCDVs expressing green, red or blue fluorescent proteins via conjunctival (ocular, Oc, intra-nasal (IN or intra-tracheal (IT inoculation. Two days post-inoculation sentinel ferrets were placed in physically separated adjacent cages to assess airborne transmission. All donor ferrets developed lymphopenia, fever and lethargy, showed progressively increasing systemic viral loads and were euthanized 14 to 16 days post-inoculation. Systemic replication of virus inoculated via the Oc, IN and IT routes was detected in 2/6, 5/6 and 6/6 ferrets, respectively. In five donor ferrets the IT delivered virus dominated, although replication of two or three different viruses was detected in 5/6 animals. Single lymphocytes expressing multiple fluorescent proteins were abundant in peripheral blood and lymphoid tissues, demonstrating the occurrence of double and triple virus infections. Transmission occurred efficiently and all recipient ferrets showed evidence of infection between 18 and 22 days post-inoculation of the donor ferrets. In all cases, airborne transmission resulted in replication of a single-colored virus, which was the dominant virus in the donor ferret. This study demonstrates that morbilliviruses can use multiple entry routes in parallel, and co-infection of cells during viral dissemination in the host is common. Airborne transmission was efficient, although
de Vries, Rory D; Ludlow, Martin; de Jong, Alwin; Rennick, Linda J; Verburgh, R Joyce; van Amerongen, Geert; van Riel, Debby; van Run, Peter R W A; Herfst, Sander; Kuiken, Thijs; Fouchier, Ron A M; Osterhaus, Albert D M E; de Swart, Rik L; Duprex, W Paul
Identification of cellular receptors and characterization of viral tropism in animal models have vastly improved our understanding of morbillivirus pathogenesis. However, specific aspects of viral entry, dissemination and transmission remain difficult to recapitulate in animal models. Here, we used three virologically identical but phenotypically distinct recombinant (r) canine distemper viruses (CDV) expressing different fluorescent reporter proteins for in vivo competition and airborne transmission studies in ferrets (Mustela putorius furo). Six donor ferrets simultaneously received three rCDVs expressing green, red or blue fluorescent proteins via conjunctival (ocular, Oc), intra-nasal (IN) or intra-tracheal (IT) inoculation. Two days post-inoculation sentinel ferrets were placed in physically separated adjacent cages to assess airborne transmission. All donor ferrets developed lymphopenia, fever and lethargy, showed progressively increasing systemic viral loads and were euthanized 14 to 16 days post-inoculation. Systemic replication of virus inoculated via the Oc, IN and IT routes was detected in 2/6, 5/6 and 6/6 ferrets, respectively. In five donor ferrets the IT delivered virus dominated, although replication of two or three different viruses was detected in 5/6 animals. Single lymphocytes expressing multiple fluorescent proteins were abundant in peripheral blood and lymphoid tissues, demonstrating the occurrence of double and triple virus infections. Transmission occurred efficiently and all recipient ferrets showed evidence of infection between 18 and 22 days post-inoculation of the donor ferrets. In all cases, airborne transmission resulted in replication of a single-colored virus, which was the dominant virus in the donor ferret. This study demonstrates that morbilliviruses can use multiple entry routes in parallel, and co-infection of cells during viral dissemination in the host is common. Airborne transmission was efficient, although transmission of
Thuy, Duong Mai; Peacock, Thomas P; Bich, Vu Thi Ngoc; Fabrizio, Thomas; Hoang, Dang Nguyen; Tho, Nguyen Dang; Diep, Nguyen Thi; Nguyen, Minh; Hoa, Le Nguyen Minh; Trang, Hau Thi Thu; Choisy, Marc; Inui, Ken; Newman, Scott; Trung, Nguyen Vu; van Doorn, Rogier; To, Thanh Long; Iqbal, Munir; Bryant, Juliet E
Despite their classification as low pathogenicity avian influenza viruses (LPAIV), A/H9N2 viruses cause significant losses in poultry in many countries throughout Asia, the Middle East and North Africa. To date, poultry surveillance in Vietnam has focused on detection of influenza H5 viruses, and there is limited understanding of influenza H9 epidemiology and transmission dynamics. We determined prevalence and diversity of influenza A viruses in chickens from live bird markets (LBM) of 7 northern Vietnamese provinces, using pooled oropharyngeal swabs collected from October to December 2014. Screening by real time RT-PCR revealed 1207/4900 (24.6%) of pooled swabs to be influenza A virus positive; overall prevalence estimates after accounting for pooling (5 swabs/pools) were 5.8% (CI 5.4-6.0). Subtyping was performed on 468 pooled swabs with M gene Ctinfluenza H7 was detected; 422 (90.1%) were H9 positive; and 22 (4.7%) were H5 positive. There was no evidence was of interaction between H9 and H5 virus detection rates. We sequenced 17 whole genomes of A/H9N2, 2 of A/H5N6, and 11 partial genomes. All H9N2 viruses had internal genes that clustered with genotype 57 and were closely related to Chinese human isolates of A/H7N9 and A/H10N8. Using a nucleotide divergence cutoff of 98%, we identified 9 distinct H9 genotypes. Phylogenetic analysis suggested multiple introductions of H9 viruses to northern Vietnam rather than in-situ transmission. Further investigations of H9 prevalence and diversity in other regions of Vietnam are warranted to assess H9 endemicity elsewhere in the country. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.
Faria, N. R.; Quick, J.; Claro, I. M.; Thézé, J.; de Jesus, J. G.; Giovanetti, M.; Kraemer, M. U. G.; Hill, S. C.; Black, A.; da Costa, A. C.; Franco, L. C.; Silva, S. P.; Wu, C.-H.; Raghwani, J.; Cauchemez, S.; Du Plessis, L.; Verotti, M. P.; de Oliveira, W. K.; Carmo, E. H.; Coelho, G. E.; Santelli, A. C. F. S.; Vinhal, L. C.; Henriques, C. M.; Simpson, J. T.; Loose, M.; Andersen, K. G.; Grubaugh, N. D.; Somasekar, S.; Chiu, C. Y.; Muñoz-Medina, J. E.; Gonzalez-Bonilla, C. R.; Arias, C. F.; Lewis-Ximenez, L. L.; Baylis, S. A.; Chieppe, A. O.; Aguiar, S. F.; Fernandes, C. A.; Lemos, P. S.; Nascimento, B. L. S.; Monteiro, H. A. O.; Siqueira, I. C.; de Queiroz, M. G.; de Souza, T. R.; Bezerra, J. F.; Lemos, M. R.; Pereira, G. F.; Loudal, D.; Moura, L. C.; Dhalia, R.; França, R. F.; Magalhães, T.; Marques, E. T.; Jaenisch, T.; Wallau, G. L.; de Lima, M. C.; Nascimento, V.; de Cerqueira, E. M.; de Lima, M. M.; Mascarenhas, D. L.; Neto, J. P. Moura; Levin, A. S.; Tozetto-Mendoza, T. R.; Fonseca, S. N.; Mendes-Correa, M. C.; Milagres, F. P.; Segurado, A.; Holmes, E. C.; Rambaut, A.; Bedford, T.; Nunes, M. R. T.; Sabino, E. C.; Alcantara, L. C. J.; Loman, N. J.; Pybus, O. G.
Transmission of Zika virus (ZIKV) in the Americas was first confirmed in May 2015 in northeast Brazil. Brazil has had the highest number of reported ZIKV cases worldwide (more than 200,000 by 24 December 2016) and the most cases associated with microcephaly and other birth defects (2,366 confirmed by 31 December 2016). Since the initial detection of ZIKV in Brazil, more than 45 countries in the Americas have reported local ZIKV transmission, with 24 of these reporting severe ZIKV-associated disease. However, the origin and epidemic history of ZIKV in Brazil and the Americas remain poorly understood, despite the value of this information for interpreting observed trends in reported microcephaly. Here we address this issue by generating 54 complete or partial ZIKV genomes, mostly from Brazil, and reporting data generated by a mobile genomics laboratory that travelled across northeast Brazil in 2016. One sequence represents the earliest confirmed ZIKV infection in Brazil. Analyses of viral genomes with ecological and epidemiological data yield an estimate that ZIKV was present in northeast Brazil by February 2014 and is likely to have disseminated from there, nationally and internationally, before the first detection of ZIKV in the Americas. Estimated dates for the international spread of ZIKV from Brazil indicate the duration of pre-detection cryptic transmission in recipient regions. The role of northeast Brazil in the establishment of ZIKV in the Americas is further supported by geographic analysis of ZIKV transmission potential and by estimates of the basic reproduction number of the virus.
Faria, N R; Quick, J; Claro, I M; Thézé, J; de Jesus, J G; Giovanetti, M; Kraemer, M U G; Hill, S C; Black, A; da Costa, A C; Franco, L C; Silva, S P; Wu, C-H; Raghwani, J; Cauchemez, S; du Plessis, L; Verotti, M P; de Oliveira, W K; Carmo, E H; Coelho, G E; Santelli, A C F S; Vinhal, L C; Henriques, C M; Simpson, J T; Loose, M; Andersen, K G; Grubaugh, N D; Somasekar, S; Chiu, C Y; Muñoz-Medina, J E; Gonzalez-Bonilla, C R; Arias, C F; Lewis-Ximenez, L L; Baylis, S A; Chieppe, A O; Aguiar, S F; Fernandes, C A; Lemos, P S; Nascimento, B L S; Monteiro, H A O; Siqueira, I C; de Queiroz, M G; de Souza, T R; Bezerra, J F; Lemos, M R; Pereira, G F; Loudal, D; Moura, L C; Dhalia, R; França, R F; Magalhães, T; Marques, E T; Jaenisch, T; Wallau, G L; de Lima, M C; Nascimento, V; de Cerqueira, E M; de Lima, M M; Mascarenhas, D L; Neto, J P Moura; Levin, A S; Tozetto-Mendoza, T R; Fonseca, S N; Mendes-Correa, M C; Milagres, F P; Segurado, A; Holmes, E C; Rambaut, A; Bedford, T; Nunes, M R T; Sabino, E C; Alcantara, L C J; Loman, N J; Pybus, O G
Transmission of Zika virus (ZIKV) in the Americas was first confirmed in May 2015 in northeast Brazil. Brazil has had the highest number of reported ZIKV cases worldwide (more than 200,000 by 24 December 2016) and the most cases associated with microcephaly and other birth defects (2,366 confirmed by 31 December 2016). Since the initial detection of ZIKV in Brazil, more than 45 countries in the Americas have reported local ZIKV transmission, with 24 of these reporting severe ZIKV-associated disease. However, the origin and epidemic history of ZIKV in Brazil and the Americas remain poorly understood, despite the value of this information for interpreting observed trends in reported microcephaly. Here we address this issue by generating 54 complete or partial ZIKV genomes, mostly from Brazil, and reporting data generated by a mobile genomics laboratory that travelled across northeast Brazil in 2016. One sequence represents the earliest confirmed ZIKV infection in Brazil. Analyses of viral genomes with ecological and epidemiological data yield an estimate that ZIKV was present in northeast Brazil by February 2014 and is likely to have disseminated from there, nationally and internationally, before the first detection of ZIKV in the Americas. Estimated dates for the international spread of ZIKV from Brazil indicate the duration of pre-detection cryptic transmission in recipient regions. The role of northeast Brazil in the establishment of ZIKV in the Americas is further supported by geographic analysis of ZIKV transmission potential and by estimates of the basic reproduction number of the virus.
Full Text Available In chronic hepatitis B (CHB, hepatitis D virus (HDV superinfection can lead to acute liver failure. The incidence of HDV superinfection is unknown, but is often detected in immigrants from HDV endemic countries. In this report, we characterize long-term clinical and virological outcomes in a hepatitis B virus (HBV infected carrier before and after HDV superinfection, acquired from their spouse having HBV/HDV co-infection. A 38 year-old Mongolian male with CHB on anti-HBV therapy developed acute liver failure following HDV superinfection. Although he recovered, avoiding the need for liver transplant, HDV serological and molecular markers of infection persisted for the subsequent 16-month follow-up period, suggesting the development of CHB/HDV co-infection. The source of his HDV was from his wife of 10 years, a 34-year old Mongolian female known to have inactive CHB/HDV co-infection but who was not on anti-HBV therapy. Phylogenetic analysis of the complete HDV genome from the couple showed >99% similarity, with post-transmission longitudinal sequence revealing specific nucleotide substitutions between both spouse’s HDV genome sequences. This study highlights the ongoing risk of HDV superinfection due to long-term co-habitation or sexual transmission in CHB patients. The fact that transmission occurred after almost a decade of marriage may be due to host immune or environmental factors that created a more favorable condition for transmission.
Dyah Ayu Hewajuli
Full Text Available Ecology is a science studying the correlation among organisms and some environmental factors. Ecological factors play an important role to transmit Avian Influenza (AI virus and influence its stability in the environment. Avian Influenza virus is classified as type A virus and belong to Orthomyxoviridae family. The virus can infect various vertebrates, mainly birds and mammals, including human. Avian Influenza virus transmission can occur through bird migration. The bird migration patterns usually occur in the large continent covers a long distance area within a certain periode hence transmit the virus from infected birds to other birds and spread to the environment. The biotic (normal flora microbes and abiotic (physical and chemical factors play important role in transmitting the virus to susceptible avian species and influence its stability in the environment. Disinfectant can inactivate the AI virus in the environment but its effectivity is influenced by the concentration, contact time, pH, temperature and organic matter.
Klepac, Petra; Pomeroy, Laura W.; Bjørnstad, Ottar N.; Kuiken, Thijs; Osterhaus, Albert D.M.E.; Rijks, Jolianne M.
Heterogeneities in transmission among hosts can be very important in shaping infectious disease dynamics. In mammals with strong social organization, such heterogeneities are often structured by functional stage: juveniles, subadults and adults. We investigate the importance of such stage-related heterogeneities in shaping the 2002 phocine distemper virus (PDV) outbreak in the Dutch Wadden Sea, when more than 40 per cent of the harbour seals were killed. We do this by comparing the statistical fit of a hierarchy of models with varying transmission complexity: homogeneous versus heterogeneous mixing and density- versus frequency-dependent transmission. We use the stranding data as a proxy for incidence and use Poisson likelihoods to estimate the ‘who acquires infection from whom’ (WAIFW) matrix. Statistically, the model with strong heterogeneous mixing and density-dependent transmission was found to best describe the transmission dynamics. However, patterns of incidence support a model of frequency-dependent transmission among adults and juveniles. Based on the maximum-likelihood WAIFW matrix estimates, we use the next-generation formalism to calculate an R0 between 2 and 2.5 for the Dutch 2002 PDV epidemic. PMID:19364743
Torres, J M; Ramírez, M A; Morales, M; Bárcena, J; Vázquez, B; Espuña, E; Pagès-Manté, A; Sánchez-Vizcaíno, J M
We have recently developed a transmissible vaccine to immunize rabbits against myxomatosis and rabbit haemorrhagic disease based on a recombinant myxoma virus (MV) expressing the rabbit haemorrhagic disease virus (RHDV) capsid protein [Bárcena et al. Horizontal transmissible protection against myxomatosis and rabbit haemorragic disease using a recombinant myxoma virus. J. Virol. 2000;74:1114-23]. Administration of the recombinant virus protects rabbits against lethal RHDV and MV challenges. Furthermore, the recombinant virus is capable of horizontal spreading promoting protection of contact animals, thus providing the opportunity to immunize wild rabbit populations. However, potential risks must be extensively evaluated before considering its field use. In this study several safety issues concerning the proposed vaccine have been evaluated under laboratory conditions. Results indicated that vaccine administration is safe even at a 100-fold overdose. No undesirable effects were detected upon administration to immunosuppressed or pregnant rabbits. The recombinant virus maintained its attenuated phenotype after 10 passages in vivo.
Campbell, Karen M; Haldeman, Kristin; Lehnig, Chris; Munayco, Cesar V; Halsey, Eric S; Laguna-Torres, V Alberto; Yagui, Martín; Morrison, Amy C; Lin, Chii-Dean; Scott, Thomas W
Dengue is one of the most aggressively expanding mosquito-transmitted viruses. The human burden approaches 400 million infections annually. Complex transmission dynamics pose challenges for predicting location, timing, and magnitude of risk; thus, models are needed to guide prevention strategies and policy development locally and globally. Weather regulates transmission-potential via its effects on vector dynamics. An important gap in understanding risk and roadblock in model development is an empirical perspective clarifying how weather impacts transmission in diverse ecological settings. We sought to determine if location, timing, and potential-intensity of transmission are systematically defined by weather. We developed a high-resolution empirical profile of the local weather-disease connection across Peru, a country with considerable ecological diversity. Applying 2-dimensional weather-space that pairs temperature versus humidity, we mapped local transmission-potential in weather-space by week during 1994-2012. A binary classification-tree was developed to test whether weather data could classify 1828 Peruvian districts as positive/negative for transmission and into ranks of transmission-potential with respect to observed disease. We show that transmission-potential is regulated by temperature-humidity coupling, enabling epidemics in a limited area of weather-space. Duration within a specific temperature range defines transmission-potential that is amplified exponentially in higher humidity. Dengue-positive districts were identified by mean temperature >22°C for 7+ weeks and minimum temperature >14°C for 33+ weeks annually with 95% sensitivity and specificity. In elevated-risk locations, seasonal peak-incidence occurred when mean temperature was 26-29°C, coincident with humidity at its local maximum; highest incidence when humidity >80%. We profile transmission-potential in weather-space for temperature-humidity ranging 0-38°C and 5-100% at 1°C x 2
Karen M Campbell
Full Text Available Dengue is one of the most aggressively expanding mosquito-transmitted viruses. The human burden approaches 400 million infections annually. Complex transmission dynamics pose challenges for predicting location, timing, and magnitude of risk; thus, models are needed to guide prevention strategies and policy development locally and globally. Weather regulates transmission-potential via its effects on vector dynamics. An important gap in understanding risk and roadblock in model development is an empirical perspective clarifying how weather impacts transmission in diverse ecological settings. We sought to determine if location, timing, and potential-intensity of transmission are systematically defined by weather.We developed a high-resolution empirical profile of the local weather-disease connection across Peru, a country with considerable ecological diversity. Applying 2-dimensional weather-space that pairs temperature versus humidity, we mapped local transmission-potential in weather-space by week during 1994-2012. A binary classification-tree was developed to test whether weather data could classify 1828 Peruvian districts as positive/negative for transmission and into ranks of transmission-potential with respect to observed disease. We show that transmission-potential is regulated by temperature-humidity coupling, enabling epidemics in a limited area of weather-space. Duration within a specific temperature range defines transmission-potential that is amplified exponentially in higher humidity. Dengue-positive districts were identified by mean temperature >22°C for 7+ weeks and minimum temperature >14°C for 33+ weeks annually with 95% sensitivity and specificity. In elevated-risk locations, seasonal peak-incidence occurred when mean temperature was 26-29°C, coincident with humidity at its local maximum; highest incidence when humidity >80%. We profile transmission-potential in weather-space for temperature-humidity ranging 0-38°C and 5
Maurice, Huibert; Thulke, Hans-Hermann; Schmid, Julia Sabine; Stegeman, Arjan; Nielen, Mirjam
Although generally considered a rodent virus, pigs sometimes were suggested a potential reservoir host for encephalomyocarditis virus (EMCV), implying pig-to-pig transmission can cause major outbreaks in a pig population (basic reproduction ratio, R0>1). An earlier experimental study on EMCV
Maines, Taronna R; Chen, Li-Mei; Van Hoeven, Neal
Although H5N1 influenza viruses have been responsible for hundreds of human infections, these avian influenza viruses have not fully adapted to the human host. The lack of sustained transmission in humans may be due, in part, to their avian-like receptor preference. Here, we have introduced recep...
Full Text Available H9N2 subtype influenza viruses have been detected in different species of wild birds and domestic poultry in many countries for several decades. Because these viruses are of low pathogenicity in poultry, their eradication is not a priority for animal disease control in many countries, which has allowed them to continue to evolve and spread. Here, we characterized the genetic variation, receptor-binding specificity, replication capability, and transmission in mammals of a series of H9N2 influenza viruses that were detected in live poultry markets in southern China between 2009 and 2013. Thirty-five viruses represented 17 genotypes on the basis of genomic diversity, and one specific "internal-gene-combination" predominated among the H9N2 viruses. This gene combination was also present in the H7N9 and H10N8 viruses that have infected humans in China. All of the 35 viruses preferentially bound to the human-like receptor, although two also retained the ability to bind to the avian-like receptor. Six of nine viruses tested were transmissible in ferrets by respiratory droplet; two were highly transmissible. Some H9N2 viruses readily acquired the 627K or 701N mutation in their PB2 gene upon infection of ferrets, further enhancing their virulence and transmission in mammals. Our study indicates that the widespread dissemination of H9N2 viruses poses a threat to human health not only because of the potential of these viruses to cause an influenza pandemic, but also because they can function as "vehicles" to deliver different subtypes of influenza viruses from avian species to humans.
Mammen P Mammen
Full Text Available Transmission of dengue viruses (DENV, the leading cause of arboviral disease worldwide, is known to vary through time and space, likely owing to a combination of factors related to the human host, virus, mosquito vector, and environment. An improved understanding of variation in transmission patterns is fundamental to conducting surveillance and implementing disease prevention strategies. To test the hypothesis that DENV transmission is spatially and temporally focal, we compared geographic and temporal characteristics within Thai villages where DENV are and are not being actively transmitted.Cluster investigations were conducted within 100 m of homes where febrile index children with (positive clusters and without (negative clusters acute dengue lived during two seasons of peak DENV transmission. Data on human infection and mosquito infection/density were examined to precisely (1 define the spatial and temporal dimensions of DENV transmission, (2 correlate these factors with variation in DENV transmission, and (3 determine the burden of inapparent and symptomatic infections. Among 556 village children enrolled as neighbors of 12 dengue-positive and 22 dengue-negative index cases, all 27 DENV infections (4.9% of enrollees occurred in positive clusters (p < 0.01; attributable risk [AR] = 10.4 per 100; 95% confidence interval 1-19.8 per 100]. In positive clusters, 12.4% of enrollees became infected in a 15-d period and DENV infections were aggregated centrally near homes of index cases. As only 1 of 217 pairs of serologic specimens tested in positive clusters revealed a recent DENV infection that occurred prior to cluster initiation, we attribute the observed DENV transmission subsequent to cluster investigation to recent DENV transmission activity. Of the 1,022 female adult Ae. aegypti collected, all eight (0.8% dengue-infected mosquitoes came from houses in positive clusters; none from control clusters or schools. Distinguishing features between
Sreenivasan, Chithra; Thomas, Milton; Sheng, Zizhang; Hause, Ben M; Collin, Emily A; Knudsen, David E B; Pillatzki, Angela; Nelson, Eric; Wang, Dan; Kaushik, Radhey S; Li, Feng
Influenza D virus (FLUDV) is a novel influenza virus that infects cattle and swine. The goal of this study was to investigate the replication and transmission of bovine FLUDV in guinea pigs. Following direct intranasal inoculation of animals, the virus was detected in nasal washes of infected animals during the first 7 days postinfection. High viral titers were obtained from nasal turbinates and lung tissues of directly inoculated animals. Further, bovine FLUDV was able to transmit from the infected guinea pigs to sentinel animals by means of contact and not by aerosol dissemination under the experimental conditions tested in this study. Despite exhibiting no clinical signs, infected guinea pigs developed seroconversion and the viral antigen was detected in lungs of animals by immunohistochemistry. The observation that bovine FLUDV replicated in the respiratory tract of guinea pigs was similar to observations described previously in studies of gnotobiotic calves and pigs experimentally infected with bovine FLUDV but different from those described previously in experimental infections in ferrets and swine with a swine FLUDV, which supported virus replication only in the upper respiratory tract and not in the lower respiratory tract, including lung. Our study established that guinea pigs could be used as an animal model for studying this newly emerging influenza virus. Influenza D virus (FLUDV) is a novel emerging pathogen with bovine as its primary host. The epidemiology and pathogenicity of the virus are not yet known. FLUDV also spreads to swine, and the presence of FLUDV-specific antibodies in humans could indicate that there is a potential for zoonosis. Our results showed that bovine FLUDV replicated in the nasal turbinate and lungs of guinea pigs at high titers and was also able to transmit from an infected animal to sentinel animals by contact. The fact that bovine FLUDV replicated productively in both the upper and lower respiratory tracts of guinea pigs
Ferguson, Paige F. B.; Breyta, Rachel; Brito, Ilana L.; Kurath, Gael; LaDeau, Shannon L.
We have developed a dynamic epidemiological model informed by records of viral presence and genotypes to evaluate potential transmission routes maintaining a viral pathogen in economically and culturally important anadromous fish populations. In the Columbia River Basin, infectious hematopoietic necrosis virus (IHNV) causes severe disease, predominantly in juvenile steelhead trout (Oncorhynchus mykiss) and less frequently in Chinook salmon (O. tshawytscha). Mortality events following IHNV infection can be devastating for individual hatchery programs. Despite reports of high local mortality and extensive surveillance efforts, there are questions about how viral transmission is maintained. Modeling this system offers important insights into disease transmission in natural aquatic systems, as well as about the data requirements for generating accurate estimates about transmission routes and infection probabilities. We simulated six scenarios in which testing rates and the relative importance of different transmission routes varied. The simulations demonstrated that the model accurately identified routes of transmission and inferred infection probabilities accurately when there was testing of all cohort-sites. When testing records were incomplete, the model accurately inferred which transmission routes exposed particular cohort-sites but generated biased infection probabilities given exposure. After validating the model and generating guidelines for result interpretation, we applied the model to data from 14 annual cohorts (2000–2013) at 24 focal sites in a sub-region of the Columbia River Basin, the lower Columbia River (LCR), to quantify the relative importance of potential transmission routes in this focal sub-region. We demonstrate that exposure to IHNV via the return migration of adult fish is an important route for maintaining IHNV in the LCR sub-region, and the probability of infection following this exposure was relatively high at 0.16. Although only 1% of
Sherman, Michael B; Kakani, Kishore; Rochon, D'Ann; Jiang, Wen; Voss, Neil R; Smith, Thomas J
Cucumber necrosis virus (CNV) is a member of the genus Tombusvirus and has a monopartite positive-sense RNA genome. CNV is transmitted in nature via zoospores of the fungus Olpidium bornovanus As with other members of the Tombusvirus genus, the CNV capsid swells when exposed to alkaline pH and EDTA. We previously demonstrated that a P73G mutation blocks the virus from zoospore transmission while not significantly affecting replication in plants (K. Kakani, R. Reade, and D. Rochon, J Mol Biol 338:507-517, 2004, https://doi.org/10.1016/j.jmb.2004.03.008). P73 lies immediately adjacent to a putative zinc binding site (M. Li et al., J Virol 87:12166-12175, 2013, https://doi.org/10.1128/JVI.01965-13) that is formed by three icosahedrally related His residues in the N termini of the C subunit at the quasi-6-fold axes. To better understand how this buried residue might affect vector transmission, we determined the cryo-electron microscopy structure of wild-type CNV in the native and swollen state and of the transmission-defective mutant, P73G, under native conditions. With the wild-type CNV, the swollen structure demonstrated the expected expansion of the capsid. However, the zinc binding region at the quasi-6-fold at the β-annulus axes remained intact. By comparison, the zinc binding region of the P73G mutant, even under native conditions, was markedly disordered, suggesting that the β-annulus had been disrupted and that this could destabilize the capsid. This was confirmed with pH and urea denaturation experiments in conjunction with electron microscopy analysis. We suggest that the P73G mutation affects the zinc binding and/or the β-annulus, making it more fragile under neutral/basic pH conditions. This, in turn, may affect zoospore transmission. IMPORTANCE Cucumber necrosis virus (CNV), a member of the genus Tombusvirus , is transmitted in nature via zoospores of the fungus Olpidium bornovanus While a number of plant viruses are transmitted via insect vectors
Sommer, D; Heffels-Redmann, U; Köhler, K; Lierz, M; Kaleta, E F
The aim of this study was to investigate the role of the poultry red mite (Dermanyssus [D.] gallinae) in the horizontal transmission of avian influenza A virus (AIV) to chickens. This mite is the most common ectoparasite in poultry worldwide, and may play a role in the spread of infectious agents including AIV. Currently, the control of mites is difficult due to frequently developed resistance to many acaricides, their nocturnality and their ability to survive hidden without feeding for months. D. gallinae were collected in a commercial layer farm and housed in self-made fibreboard boxes. SPF chickens were intravenously infected with AIV strain A/turkey/Ontario/7732/1966 (H5N9). The viraemia in chickens was monitored and at an appropriate time point about 1000 mites were allowed to suck on the AIV infected chickens. Re-isolation of the virus from blood-filled mites was tried daily for 14 days using chicken embryo fibroblast cultures and embryonated chicken eggs. Subsequently, the virus containing mites were placed into boxes that contained naïve SPF chickens to enable virus transmission from mites to chickens. Possible transmission to the chickens was examined using clinical signs, serology, gross lesions, histopathology and immunohistochemistry. Chickens developed a dose-dependent viraemia one day after infection, therefore this day was chosen for the bloodmeal of the mites. AIV was detected in mites after bloodsucking on AIV-infected chickens over a 10-day period. Naïve SPF chickens were infected during bloodsucking of AIV carrying mites. AIV isolates in mites and in chickens were undistinguishable from the original AIV inoculum by RT-PCR. D. gallinae ingested AIV during bloodmeals on AIV infected chickens and are able to transmit AIV to SPF chickens. Therefore, mites serve as mechanical vector of AIV and may play a major role in the circulation of AIV within a facility or area although the life span of infectious virus in the mite is limited. The proven
Backx, A.; Heutink, C.G.; Rooij, van E.M.A.; Rijn, van P.A.
Potential vertical transmission of wild-type bluetongue virus serotype 8 (BTV-8) in cattle was explored in this experiment. We demonstrated transplacental transmission of wild-type BTV-8 in one calf and oral infection with BTV-8 in another calf. Following the experimental BTV-8 infection of seven
Rianka P M Vloet
Full Text Available Rift Valley fever virus (RVFV is a mosquito-borne bunyavirus of the genus Phlebovirus that is highly pathogenic to ruminants and humans. The disease is currently confined to Africa and the Arabian Peninsula, but globalization and climate change may facilitate introductions of the virus into currently unaffected areas via infected animals or mosquitoes. The consequences of such an introduction will depend on environmental factors, the availability of susceptible ruminants and the capacity of local mosquitoes to transmit the virus. We have previously demonstrated that lambs native to the Netherlands are highly susceptible to RVFV and we here report the vector competence of Culex (Cx. pipiens, the most abundant and widespread mosquito species in the country. Vector competence was first determined after artificial blood feeding of laboratory-reared mosquitoes using the attenuated Clone 13 strain. Subsequently, experiments with wild-type RVFV and mosquitoes hatched from field-collected eggs were performed. Finally, the transmission of RVFV from viremic lambs to mosquitoes was studied.Artificial feeding experiments using Clone 13 demonstrated that indigenous, laboratory-reared Cx. pipiens mosquitoes are susceptible to RVFV and that the virus can be transmitted via their saliva. Experiments with wild-type RVFV and mosquitoes hatched from field-collected eggs confirmed the vector competence of Cx. pipiens mosquitoes from the Netherlands. To subsequently investigate transmission of the virus under more natural conditions, mosquitoes were allowed to feed on RVFV-infected lambs during the viremic period. We found that RVFV is efficiently transmitted from lambs to mosquitoes, although transmission was restricted to peak viremia. Interestingly, in the mosquito-exposed skin samples, replication of RVFV was detected in previously unrecognized target cells.We here report the vector competence of Cx. pipiens mosquitoes from the Netherlands for RVFV. Both
Patrick L. Green
Full Text Available Human T-lymphotrophic virus type-1 (HTLV-1 infects approximately 15 to 20 million people worldwide, with endemic areas in Japan, the Caribbean, and Africa. The virus is spread through contact with bodily fluids containing infected cells, most often from mother to child through breast milk or via blood transfusion. After prolonged latency periods, approximately 3 to 5% of HTLV-1 infected individuals will develop either adult T-cell leukemia/lymphoma (ATL, or other lymphocyte-mediated disorders such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP. The genome of this complex retrovirus contains typical gag, pol, and env genes, but also unique nonstructural proteins encoded from the pX region. These nonstructural genes encode the Tax and Rex regulatory proteins, as well as novel proteins essential for viral spread in vivo such as, p30, p12, p13 and the antisense encoded HBZ. While progress has been made in the understanding of viral determinants of cell transformation and host immune responses, host and viral determinants of HTLV-1 transmission and spread during the early phases of infection are unclear. Improvements in the molecular tools to test these viral determinants in cellular and animal models have provided new insights into the early events of HTLV-1 infection. This review will focus on studies that test HTLV-1 determinants in context to full length infectious clones of the virus providing insights into the mechanisms of transmission and spread of HTLV-1.
Kaic, B; Gjenero-Margan, I; Aleraj, B; Ljubin-Sternak, S; Vilibic-Cavlek, T; Kilvain, S; Pavic, I; Stojanovic, D; Ilic, A
We report on three cases of symptomatic transmission of the L-Zagreb mumps vaccine virus from three vaccinated children to five adult contacts. The five contact cases were parents of the vaccinated children and presented with parotitis and in one case also with aseptic meningitis. The etiology of the contacts' illness was determined by viral culture, genomic sequencing, serology and epidemiological linking. Two of the vaccinated children developed vaccine associated parotitis as an adverse event three weeks following immunization. Symptoms in contact cases developed five to seven weeks after the vaccination of the children. The five contact cases, as well as the three children with adverse events recovered completely. The children had been vaccinated with MMR vaccine produced by the Institute of Immunology Zagreb, each of them with a different lot. One of the possible explanations for these adverse events is that the very low levels of wild mumps virus circulation in the last decade, combined with waning immunity in those who received one dose of vaccine or suffered from mumps in childhood, resulted in susceptible young adults and that this unique epidemiological situation allows us to detect horizontal transmission of mumps vaccine virus.
A Marm Kilpatrick
Full Text Available The distribution and intensity of transmission of vector-borne pathogens can be strongly influenced by the competence of vectors. Vector competence, in turn, can be influenced by temperature and viral genetics. West Nile virus (WNV was introduced into the United States of America in 1999 and subsequently spread throughout much of the Americas. Previously, we have shown that a novel genotype of WNV, WN02, first detected in 2001, spread across the US and was more efficient than the introduced genotype, NY99, at infecting, disseminating, and being transmitted by Culex mosquitoes. In the current study, we determined the relationship between temperature and time since feeding on the probability of transmitting each genotype of WNV. We found that the advantage of the WN02 genotype increases with the product of time and temperature. Thus, warmer temperatures would have facilitated the invasion of the WN02 genotype. In addition, we found that transmission of WNV accelerated sharply with increasing temperature, T, (best fit by a function of T(4 showing that traditional degree-day models underestimate the impact of temperature on WNV transmission. This laboratory study suggests that both viral evolution and temperature help shape the distribution and intensity of transmission of WNV, and provides a model for predicting the impact of temperature and global warming on WNV transmission.
Cavarelli, M; Scarlatti, G
The World Health Organization (WHO) and United Nations Programme on HIV/AIDS (UNAIDS) estimated that an additional 370 000 new human immunodeficiency virus type 1 (HIV-1) infections occurred in children in 2009, mainly through mother-to-child transmission (MTCT). Intrapartum transmission contributes to approximately 20-25% of infections, in utero transmission to 5-10% and postnatal transmission to an additional 10-15% of cases. MTCT accounts for only a few hundred infected newborns in those countries in which services are established for voluntary counselling and testing of pregnant women, and a supply of antiretroviral drugs is available throughout pregnancy with recommendations for elective Caesarean section and avoidance of breastfeeding. The single-dose nevirapine regimen has provided the momentum to initiate MTCT programmes in many resource-limited countries; however, regimens using a combination of antiretroviral drugs are needed also to effectively reduce transmission via breastfeeding. 2011 The Association for the Publication of the Journal of Internal Medicine.
Brian J Willett
Full Text Available Following long-term infection with virus derived from the pathogenic GL8 molecular clone of feline immunodeficiency virus (FIV, a range of viral variants emerged with distinct modes of interaction with the viral receptors CD134 and CXCR4, and sensitivities to neutralizing antibodies. In order to assess whether this viral diversity would be maintained following subsequent transmission, a synthetic quasispecies was reconstituted comprising molecular clones bearing envs from six viral variants and its replicative capacity compared in vivo with a clonal preparation of the parent virus. Infection with either clonal (Group 1 or diverse (Group 2 challenge viruses, resulted in a reduction in CD4+ lymphocytes and an increase in CD8+ lymphocytes. Proviral loads were similar in both study groups, peaking by 10 weeks post-infection, a higher plateau (set-point being achieved and maintained in study Group 1. Marked differences in the ability of individual viral variants to replicate were noted in Group 2; those most similar to GL8 achieved higher viral loads while variants such as the chimaeras bearing the B14 and B28 Envs grew less well. The defective replication of these variants was not due to suppression by the humoral immune response as virus neutralising antibodies were not elicited within the study period. Similarly, although potent cellular immune responses were detected against determinants in Env, no qualitative differences were revealed between animals infected with either the clonal or the diverse inocula. However, in vitro studies indicated that the reduced replicative capacity of variants B14 and B28 in vivo was associated with altered interactions between the viruses and the viral receptor and co-receptor. The data suggest that viral variants with GL8-like characteristics have an early, replicative advantage and should provide the focus for future vaccine development.
Borsheim, K.Y.; Bratbak, G.; Heldal, M.
Bacteria and virus particles were harvested from water samples by ultracentrifugation directly onto Formvar-coated electron microscopy grids and counted in a transmission electron microscope. With this technique, we have counted and sized bacteria and viruses in marine water samples and during laboratory incubations. By X-ray microanalysis, we could determine the elemental composition and dry-matter content of individual bacteria. The dry weight/volume ratio for the bacteria was 600 fg of dry weight microns-3. The potassium content of the bacteria was normal compared with previous estimates from other bacterial assemblages; thus, this harvesting procedure did not disrupt the bacterial cells. Virus particles were, by an order of magnitude, more abundant than bacteria in marine coastal waters. During the first 5 to 7 days of incubation, the total number of viruses increased exponentially at a rate of 0.4 day-1 and thereafter declined. The high proliferation rate suggests that viral parasitism may affect mortality of bacteria in aquatic environments
Anabestani, Ameneh; Behjatnia, Seyed Ali Akbar; Izadpanah, Keramat; Tabein, Saeid
Beet curly top virus (BCTV) and beet curly top Iran virus (BCTIV) are known as the causal agents of curly top disease in beet and several other dicotyledonous plants in Iran. These viruses are transmitted by Circulifer species, and until now, there has been no confirmed report of their seed transmission. A percentage (38.2–78.0%) of the seedlings developed from the seeds of a petunia local cultivar under insect-free conditions showed stunting, interveinal chlorosis, leaf curling, and vein swelling symptoms, and were infected by BCTV when tested by PCR. Presence of BCTV in seed extracts of petunia local cultivar was confirmed by PCR and IC-PCR, followed by sequencing. Agroinoculation of curly top free petunia plants with a BCTV infectious clone resulted in BCTV infection of plants and their developed seeds. These results show the seed infection and transmission of BCTV in a local cultivar of petunia. Similar experiments performed with BCTIV showed that this virus is also seed transmissible in the same cultivar of petunia, although with a lower rate (8.8–18.5%). Seed transmission of curly top viruses may have significant implications in the epidemiology of these viruses. PMID:29035342
In the United States, yellow fever (YF) vaccination is recommended for travelers and active duty military members visiting endemic areas of sub-Saharan Africa and Central/South America. The American Red Cross recommends that recipients of YF vaccine defer blood product donation for 2 weeks because of the theoretical risk for transmission from a viremic donor. On April 10, 2009, a hospital blood bank supervisor learned that, on March 27, blood products had been collected from 89 U.S. active duty trainees who had received YF vaccine 4 days before donation. This report summarizes the subsequent investigation by the hospital and CDC to identify lapses in donor deferral and to determine whether transfusion-related transmission of YF vaccine virus occurred. The investigation found that a recent change in the timing of trainee vaccination had occurred and that vaccinees had not reported recent YF vaccination status at time of donation. Despite a prompt recall, six units of blood products were transfused into five patients. No clinical evidence or laboratory abnormalities consistent with a serious adverse reaction were identified in four recipients within the first month after transfusion; the fifth patient, who had prostate cancer and end-stage, transfusion-dependent, B-cell lymphoma, died while in hospice care. Three of the four surviving patients had evidence of serologic response to YF vaccine virus. This report provides evidence that transfusion-related transmission of YF vaccine virus can occur and underscores the need for careful screening and deferral of recently vaccinated blood donors.
Monica K Borucki
Full Text Available One of the hurdles to understanding the role of viral quasispecies in RNA virus cross-species transmission (CST events is the need to analyze a densely sampled outbreak using deep sequencing in order to measure the amount of mutation occurring on a small time scale. In 2009, the California Department of Public Health reported a dramatic increase (350 in the number of gray foxes infected with a rabies virus variant for which striped skunks serve as a reservoir host in Humboldt County. To better understand the evolution of rabies, deep-sequencing was applied to 40 unpassaged rabies virus samples from the Humboldt outbreak. For each sample, approximately 11 kb of the 12 kb genome was amplified and sequenced using the Illumina platform. Average coverage was 17,448 and this allowed characterization of the rabies virus population present in each sample at unprecedented depths. Phylogenetic analysis of the consensus sequence data demonstrated that samples clustered according to date (1995 vs. 2009 and geographic location (northern vs. southern. A single amino acid change in the G protein distinguished a subset of northern foxes from a haplotype present in both foxes and skunks, suggesting this mutation may have played a role in the observed increased transmission among foxes in this region. Deep-sequencing data indicated that many genetic changes associated with the CST event occurred prior to 2009 since several nonsynonymous mutations that were present in the consensus sequences of skunk and fox rabies samples obtained from 20032010 were present at the sub-consensus level (as rare variants in the viral population in skunk and fox samples from 1995. These results suggest that analysis of rare variants within a viral population may yield clues to ancestral genomes and identify rare variants that have the potential to be selected for if environment conditions change.
Full Text Available Abstract Background Foamy viruses are exogenous complex retroviruses that are highly endemic in several animal species, including monkeys and apes, where they cause persistent infection. Simian foamy viral (SFV infection has been reported in few persons occupationally exposed to non-human primates (NHP in zoos, primate centers and laboratories, and recently in few hunters from central Africa. Most of the epidemiological works performed among NHP populations concern cross-sectional studies without long-term follow-up. Therefore, the exact timing and the modes of transmission of SFVs remain not well known, although sexual and oral transmissions have been suspected. We have conducted a longitudinal study in a free-breeding colony of Macaca tonkeana in order (1 to determine the prevalence of the infection by foamy viruses, (2 to characterize molecularly the viruses infecting such animals, (3 to study their genetic variability overtime by long-term follow-up of several DNA samples in a series of specific animals, and (4 to get new insights concerning the timing and the modes of SFVs primary infection in these monkeys by combining serology and molecular means, as well as studies of familial structures and long-term behavioral observations. Results/conclusion We first demonstrated that this colony was highly endemic for SFVs, with a clear increase of seroprevalence with age. Only 4.7% of immatures, and 43,7% of sub-adults were found seropositive, while 89.5% of adults exhibited antibodies directed against SFV. We further showed that 6 different strains of foamy viruses (exhibiting a very low intra-strain and overtime genetic variability in the integrase gene are circulating within this group. This suggests a possible infection by different strains within an animal. Lastly, we provide strong evidence that foamy viruses are mostly acquired through severe bites, mainly in sub-adults or young adults. Most cases of seroconversion occur after 7 years of age
Doceul, Virginie; Bagdassarian, Eugénie; Demange, Antonin; Pavio, Nicole
During the past ten years, several new hepatitis E viruses (HEVs) have been identiﬁed in various animal species. In parallel, the number of reports of autochthonous hepatitis E in Western countries has increased as well, raising the question of what role these possible animal reservoirs play in human infections. The aim of this review is to present the recent discoveries of animal HEVs and their classiﬁcation within the Hepeviridae family, their zoonotic and species barrier crossing potential, and possible use as models to study hepatitis E pathogenesis. Lastly, this review describes the transmission pathways identiﬁed from animal sources.
Full Text Available During the past ten years, several new hepatitis E viruses (HEVs have been identiﬁed in various animal species. In parallel, the number of reports of autochthonous hepatitis E in Western countries has increased as well, raising the question of what role these possible animal reservoirs play in human infections. The aim of this review is to present the recent discoveries of animal HEVs and their classiﬁcation within the Hepeviridae family, their zoonotic and species barrier crossing potential, and possible use as models to study hepatitis E pathogenesis. Lastly, this review describes the transmission pathways identiﬁed from animal sources.
Scott C. Weaver
Full Text Available The mechanisms responsible for the dramatic emergence of Zika virus (ZIKV, accompanied by congenital Zika syndrome and Guillain-Barré syndrome (GBS, remain unclear. However, two hypotheses are prominent: (i evolution for enhanced urban transmission via adaptation to mosquito vectors, or for enhanced human infection to increase amplification, or (ii the stochastic introduction of ZIKV into large, naive human populations in regions with abundant Aedes aegypti populations, leading to enough rare, severe infection outcomes for their first recognition. Advances in animal models for human infection combined with improvements in serodiagnostics, better surveillance, and reverse genetic approaches should provide more conclusive evidence of whether mosquito transmission or human pathogenesis changed coincidentally with emergence in the South Pacific and the Americas. Ultimately, understanding the mechanisms of epidemic ZIKV emergence, and its associated syndromes, is critical to predict future risks as well as to target surveillance and control measures in key locations.
Lourenço, José; Maia de Lima, Maricelia; Faria, Nuno Rodrigues; Walker, Andrew; Kraemer, Moritz Ug; Villabona-Arenas, Christian Julian; Lambert, Ben; Marques de Cerqueira, Erenilde; Pybus, Oliver G; Alcantara, Luiz Cj; Recker, Mario
The Zika virus has emerged as a global public health concern. Its rapid geographic expansion is attributed to the success of Aedes mosquito vectors, but local epidemiological drivers are still poorly understood. Feira de Santana played a pivotal role in the Chikungunya epidemic in Brazil and was one of the first urban centres to report Zika infections. Using a climate-driven transmission model and notified Zika case data, we show that a low observation rate and high vectorial capacity translated into a significant attack rate during the 2015 outbreak, with a subsequent decline in 2016 and fade-out in 2017 due to herd-immunity. We find a potential Zika-related, low risk for microcephaly per pregnancy, but with significant public health impact given high attack rates. The balance between the loss of herd-immunity and viral re-importation will dictate future transmission potential of Zika in this urban setting.
Niqueux, Éric; Picault, Jean-Paul; Amelot, Michel; Allée, Chantal; Lamandé, Josiane; Guillemoto, Carole; Pierre, Isabelle; Massin, Pascale; Blot, Guillaume; Briand, François-Xavier; Rose, Nicolas; Jestin, Véronique
EU annual serosurveillance programs show that domestic duck flocks have the highest seroprevalence of H5 antibodies, demonstrating the circulation of notifiable avian influenza virus (AIV) according to OIE, likely low pathogenic (LP). Therefore, transmission characteristics of LPAIV within these flocks can help to understand virus circulation and possible risk of propagation. This study aimed at estimating transmission parameters of four H5 LPAIV (three field strains from French poultry and decoy ducks, and one clonal reverse-genetics strain derived from one of the former), using a SIR model to analyze data from experimental infections in SPF Muscovy ducks. The design was set up to accommodate rearing on wood shavings with a low density of 1.6 ducks/m(2): 10 inoculated ducks were housed together with 15 contact-exposed ducks. Infection was monitored by RNA detection on oropharyngeal and cloacal swabs using real-time RT-PCR with a cutoff corresponding to 2-7 EID50. Depending on the strain, the basic reproduction number (R0) varied from 5.5 to 42.7, confirming LPAIV could easily be transmitted to susceptible Muscovy ducks. The lowest R0 estimate was obtained for a H5N3 field strain, due to lower values of transmission rate and duration of infectious period, whereas reverse-genetics derived H5N1 strain had the highest R0. Frequency and intensity of clinical signs were also variable between strains, but apparently not associated with longer infectious periods. Further comparisons of quantitative transmission parameters may help to identify relevant viral genetic markers for early detection of potentially more virulent strains during surveillance of LPAIV. Copyright © 2013 Elsevier B.V. All rights reserved.
Full Text Available Introduction. During the 2014–2016 West-African Ebola virus disease (EVD outbreak, some HCWs from Western countries became infected despite proper equipment and training on EVD infection prevention and control (IPC standards. Despite their high awareness toward EVD, some of them could not recall the transmission routes. We explored these incidents by recalling the stories of infected Western HCWs who had no known directly exposures to blood/bodily fluids from EVD patients. Methodology. We carried out conventional and unconventional literature searches through the web using the keyword “Ebola” looking for interviews and reports released by the infected HCWs and/or the healthcare organizations. Results. We identified fourteen HCWs, some infected outside West Africa and some even classified at low EVD risk. None of them recalled accidents, unintentional exposures, or any IPC violation. Infection transmission was thus inexplicable through the acknowledged transmission routes. Conclusions. We formulated two hypotheses: inapparent exposures to blood/bodily fluids or transmission due to asymptomatic/mildly symptomatic carriers. This study is in no way intended to be critical with the healthcare organizations which, thanks to their interventions, put an end to a large EVD outbreak that threatened the regional and world populations.
de Waal, Leon; Smits, Saskia L.; Veldhuis Kroeze, Edwin J. B.; van Amerongen, Geert; Pohl, Marie O.; Osterhaus, Albert D. M. E.; Stittelaar, Koert J.
Human respiratory syncytial virus (HRSV) causes substantial morbidity and mortality in vulnerable patients, such as the very young, the elderly, and immunocompromised individuals of any age. Nosocomial transmission of HRSV remains a serious challenge in hospital settings, with intervention strategies largely limited to infection control measures, including isolation of cases, high standards of hand hygiene, cohort nursing, and use of personal protective equipment. No vaccines against HRSV are currently available, and treatment options are largely supportive care and expensive monoclonal antibody or antiviral therapy. The limitations of current animal models for HRSV infection impede the development of new preventive and therapeutic agents, and the assessment of their potential for limiting HRSV transmission, in particular in nosocomial settings. Here, we demonstrate the efficient transmission of HRSV from immunocompromised ferrets to both immunocompromised and immunocompetent contact ferrets, with pathological findings reproducing HRSV pathology in humans. The immunocompromised ferret-HRSV model represents a novel tool for the evaluation of intervention strategies against nosocomial transmission of HRSV. PMID:29301313
Simanjuntak, Yogy; Liang, Jian-Jong; Chen, Si-Yu; Li, Jin-Kun; Lee, Yi-Ling; Wu, Han-Chung; Lin, Yi-Ling
Despite the low case fatality, Zika virus (ZIKV) infection has been associated with microcephaly in infants and Guillain-Barré syndrome. Antiviral and vaccine developments against ZIKV are still ongoing; therefore, in the meantime, preventing the disease transmission is critical. Primarily transmitted by Aedes species mosquitoes, ZIKV also can be sexually transmitted. We used AG129 mice lacking interferon-α/β and -γ receptors to study the testicular pathogenesis and sexual transmission of ZIKV. Infection of ZIKV progressively damaged mouse testes, increased testicular oxidative stress as indicated by the levels of reactive oxygen species, nitric oxide, glutathione peroxidase 4, spermatogenesis-associated-18 homolog in sperm and pro-inflammatory cytokines including IL-1β, IL-6, and G-CSF. We then evaluated the potential role of the antioxidant ebselen (EBS) in alleviating the testicular pathology with ZIKV infection. EBS treatment significantly reduced ZIKV-induced testicular oxidative stress, leucocyte infiltration and production of pro-inflammatory response. Furthermore, it improved testicular pathology and prevented the sexual transmission of ZIKV in a male-to-female mouse sperm transfer model. EBS is currently in clinical trials for various diseases. ZIKV infection could be on the list for potential use of EBS, for alleviating the testicular pathogenesis with ZIKV infection and preventing its sexual transmission.
Full Text Available Despite the low case fatality, Zika virus (ZIKV infection has been associated with microcephaly in infants and Guillain-Barré syndrome. Antiviral and vaccine developments against ZIKV are still ongoing; therefore, in the meantime, preventing the disease transmission is critical. Primarily transmitted by Aedes species mosquitoes, ZIKV also can be sexually transmitted. We used AG129 mice lacking interferon-α/β and -γ receptors to study the testicular pathogenesis and sexual transmission of ZIKV. Infection of ZIKV progressively damaged mouse testes, increased testicular oxidative stress as indicated by the levels of reactive oxygen species, nitric oxide, glutathione peroxidase 4, spermatogenesis-associated-18 homolog in sperm and pro-inflammatory cytokines including IL-1β, IL-6, and G-CSF. We then evaluated the potential role of the antioxidant ebselen (EBS in alleviating the testicular pathology with ZIKV infection. EBS treatment significantly reduced ZIKV-induced testicular oxidative stress, leucocyte infiltration and production of pro-inflammatory response. Furthermore, it improved testicular pathology and prevented the sexual transmission of ZIKV in a male-to-female mouse sperm transfer model. EBS is currently in clinical trials for various diseases. ZIKV infection could be on the list for potential use of EBS, for alleviating the testicular pathogenesis with ZIKV infection and preventing its sexual transmission.
Mulcahy, D.; Pascho, R.J.
The control of epizootics of infectious haematopoietic necrosis (IIHN) virus in salmonid fishes is presently based on examination and certification of adult brood fish to prevent the introduction of virus-infected eggs into hatcheries (Canadian Fisherics and Marine Service 1976; McDaniel 1979). This strategy is based on the assumption that the virus is vertically transmitted in association with the gametes. However, evidence for vertical transmission of lHN virus is circumstantial, based mostly on the appearance of the disease outside the enzootic area (the west coast of North America) in fish hatched from eggs obtained from within that area (Plumb 1972; Holway & Smith 1973; Wolf, Quimby, Pettijohn & Landolt 1973, Sano, Nishimura, Okamoto, Yamazaki, Hanada & Watanabe 1977. Carlisle, Schat & Elston 1979). An indirect demonstration of vertical transmission was made by placing known virus-free fish in the water above and below raceways containing fish that suffered an IEEN epizootic in an cffort to climinate waterborne virus as a source of infection (Wingficid & Chan 1970). The fish placed below the raceway developed IHN, due to waterborne virus released from the affected fish in the raceway, but the fish placed above the raceway failed to develop IHN. These results suggested that the source of infection of the fish in the raceway was not the water supply, although it is possible that the virus was no longer present in the water supply at the time the sentinel fish were exposed to the water.
Fujino, Kan; Yamamoto, Yusuke; Daito, Takuji; Makino, Akiko; Honda, Tomoyuki; Tomonaga, Keizo
Borna disease virus (BoDV), a prototype of mammalian bornavirus, is a non-segmented, negative strand RNA virus that often causes severe neurological disorders in infected animals, including horses and sheep. Unique among animal RNA viruses, BoDV transcribes and replicates non-cytopathically in the cell nucleus, leading to establishment of long-lasting persistent infection. This striking feature of BoDV indicates its potential as an RNA virus vector system. It has previously been demonstrated by our team that recombinant BoDV (rBoDV) lacking an envelope glycoprotein (G) gene develops persistent infections in transduced cells without loss of the viral genome. In this study, a novel non-transmissive rBoDV, rBoDV ΔMG, which lacks both matrix (M) and G genes in the genome, is reported. rBoDV-ΔMG expressing green fluorescence protein (GFP), rBoDV ΔMG-GFP, was efficiently generated in Vero/MG cells stably expressing both BoDV M and G proteins. Infection with rBoDV ΔMG-GFP was persistently maintained in the parent Vero cells without propagation within cell culture. The optimal ratio of M and G for efficient viral particle production by transient transfection of M and G expression plasmids into cells persistently infected with rBoDV ΔMG-GFP was also demonstrated. These findings indicate that the rBoDV ΔMG-based BoDV vector may provide an extremely safe virus vector system and could be a novel strategy for investigating the function of M and G proteins and the host range of bornaviruses. © 2017 The Societies and John Wiley & Sons Australia, Ltd.
Clavijo, Gabriel; Williams, Trevor; Muñoz, Delia; Caballero, Primitivo; López-Ferber, Miguel
An insect nucleopolyhedrovirus naturally survives as a mixture of at least nine genotypes. Infection by multiple genotypes results in the production of virus occlusion bodies (OBs) with greater pathogenicity than those of any genotype alone. We tested the hypothesis that each OB contains a genotypically diverse population of virions. Few insects died following inoculation with an experimental two-genotype mixture at a dose of one OB per insect, but a high proportion of multiple infections were observed (50%), which differed significantly from the frequencies predicted by a non-associated transmission model in which genotypes are segregated into distinct OBs. By contrast, insects that consumed multiple OBs experienced higher mortality and infection frequencies did not differ significantly from those of the non-associated model. Inoculation with genotypically complex wild-type OBs indicated that genotypes tend to be transmitted in association, rather than as independent entities, irrespective of dose. To examine the hypothesis that virions may themselves be genotypically heterogeneous, cell culture plaques derived from individual virions were analysed to reveal that one-third of virions was of mixed genotype, irrespective of the genotypic composition of the OBs. We conclude that co-occlusion of genotypically distinct virions in each OB is an adaptive mechanism that favours the maintenance of virus diversity during insect-to-insect transmission. PMID:19939845
Jeffers, Liesl K.; Madden, Vicki; Webster-Cyriaque, Jennifer
Background: In this study, it was determined that BKV is shed in saliva and an in vitro model system was developed whereby BKV can productively infect both submandibular (HSG) and parotid (HSY) salivary gland cell lines. Results: BKV was detected in oral fluids using quantitative real-time PCR (QRTPCR). BKV infection was determined using quantitative RT-PCR, immunofluorescence and immunoblotting assays. The infectivity of BKV was inhibited by pre-incubation of the virus with gangliosides that saturated the major capsid protein, VP1, halting receptor mediated BKV entry into salivary gland cells. Examination of infected cultures by transmission electron microscopy revealed 45-50 nm BK virions clearly visible within the cells. Subsequent to infection, encapsidated BK virus was detected in the supernatant. Conclusion: We thus demonstrated that BKV was detected in oral fluids and that BK infection and replication occur in vitro in salivary gland cells. These data collectively suggest the potential for BKV oral route of transmission and oral pathogenesis.
Blancett, Candace D; Fetterer, David P; Koistinen, Keith A; Morazzani, Elaine M; Monninger, Mitchell K; Piper, Ashley E; Kuehl, Kathleen A; Kearney, Brian J; Norris, Sarah L; Rossi, Cynthia A; Glass, Pamela J; Sun, Mei G
A method for accurate quantitation of virus particles has long been sought, but a perfect method still eludes the scientific community. Electron Microscopy (EM) quantitation is a valuable technique because it provides direct morphology information and counts of all viral particles, whether or not they are infectious. In the past, EM negative stain quantitation methods have been cited as inaccurate, non-reproducible, and with detection limits that were too high to be useful. To improve accuracy and reproducibility, we have developed a method termed Scanning Transmission Electron Microscopy - Virus Quantitation (STEM-VQ), which simplifies sample preparation and uses a high throughput STEM detector in a Scanning Electron Microscope (SEM) coupled with commercially available software. In this paper, we demonstrate STEM-VQ with an alphavirus stock preparation to present the method's accuracy and reproducibility, including a comparison of STEM-VQ to viral plaque assay and the ViroCyt Virus Counter. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.
Gibbs, E P; Herniman, K A; Lawman, M J; Sellers, R F
After exposure for two hours to cattle with foot-and-mouth disease, each of the five species of deer found in the British countryside became infected. Clinical disease was typical and severe in the roe and muntjac deer, with some animals dying, less severe in the sika deer and usually subclinical in the fallow and red deer. Each species transmitted disease to its own species and to cattle and sheep. The amounts of virus present in the blood, and in oesophageal/pharyngeal samples and excreted as an aerosol during the course of the infection in the deer were similar to those recorded for the sheep and cattle in the same experiment. The fallow and sika deer commonly carried virus in the pharynx beyond 28 days after exposure; some red deer also became carriers. In epidemics of foot-and-mouth disease in the UK, it is likely that deer would have such intimate contact with farm animals as occurred in this study. The natural behavior of free-living deer in the UK suggests that, although the five species are susceptible to foot-and-mouth disease, they are unlikely to be an important factor in the maintenance and transmission of the virus during an epidemic of foot-and-mouth disease in domestic livestock.
Full Text Available Zika virus (ZIKV is primarily transmitted by Aedes mosquitoes in the subgenus Stegomyia but can also be transmitted sexually and vertically in humans. STAT1 is an important downstream factor that mediates type I and II interferon signaling. In the current study, we showed that mice with STAT1 knockout (Stat1-/- were highly susceptible to ZIKV infection. As low as 5 plaque-forming units of ZIKV could cause viremia and death in Stat1-/- mice. ZIKV replication was initially detected in the spleen but subsequently spread to the brain with concomitant reduction of the virus in the spleen in the infected mice. Furthermore, ZIKV could be transmitted from mosquitoes to Stat1-/- mice back to mosquitoes and then to naïve Stat1-/- mice. The 50% mosquito infectious dose of viremic Stat1-/- mouse blood was close to 810 focus-forming units (ffu/ml. Our further studies indicated that the activation of macrophages and conventional dendritic cells were likely critical for the resolution of ZIKV infection. The newly developed mouse and mosquito transmission models for ZIKV infection will be useful for the evaluation of antiviral drugs targeting the virus, vector, and host.
Sun, Hailiang; Blackmon, Sherry; Yang, Guohua; Waters, Kaitlyn; Li, Tao; Tangwangvivat, Ratanaporn; Xu, Yifei; Shyu, Daniel; Wen, Feng; Cooley, Jim; Senter, Lucy; Lin, Xiaoxu; Jarman, Richard; Hanson, Larry; Webby, Richard; Wan, Xiu-Feng
Two subtypes of influenza A virus (IAV), avian-origin canine influenza virus (CIV) H3N2 (CIV-H3N2) and equine-origin CIV H3N8 (CIV-H3N8), are enzootic in the canine population. Dogs have been demonstrated to seroconvert in response to diverse IAVs, and naturally occurring reassortants of CIV-H3N2 and the 2009 H1N1 pandemic virus (pdmH1N1) have been isolated. We conducted a thorough phenotypic evaluation of CIV-H3N2 in order to assess its threat to human health. Using ferret-generated antiserum, we determined that CIV-H3N2 is antigenically distinct from contemporary human H3N2 IAVs, suggesting that there may be minimal herd immunity in humans. We assessed the public health risk of CIV-H3N2 × pandemic H1N1 (pdmH1N1) reassortants by characterizing their in vitro genetic compatibility and in vivo pathogenicity and transmissibility. Using a luciferase minigenome assay, we quantified the polymerase activity of all possible 16 ribonucleoprotein (RNP) complexes (PB2, PB1, PA, NP) between CIV-H3N2 and pdmH1N1, identifying some combinations that were more active than either parental virus complex. Using reverse genetics and fixing the CIV-H3N2 hemagglutinin (HA), we found that 51 of the 127 possible reassortant viruses were viable and able to be rescued. Nineteen of these reassortant viruses had high-growth phenotypes in vitro , and 13 of these replicated in mouse lungs. A single reassortant with the NP and HA gene segments from CIV-H3N2 was selected for characterization in ferrets. The reassortant was efficiently transmitted by contact but not by the airborne route and was pathogenic in ferrets. Our results suggest that CIV-H3N2 reassortants may pose a moderate risk to public health and that the canine host should be monitored for emerging IAVs. IMPORTANCE IAV pandemics are caused by the introduction of novel viruses that are capable of efficient and sustained transmission into a human population with limited herd immunity. Dogs are a a potential mixing vessel for avian
Full Text Available The dramatic global expansion of Aedes albopictus in the last three decades has increased public health concern because it is a potential vector of numerous arthropod-borne viruses (arboviruses, including the most prevalent arboviral pathogen of humans, dengue virus (DENV. Ae. aegypti is considered the primary DENV vector and has repeatedly been incriminated as a driving force in dengue's worldwide emergence. What remains unresolved is the extent to which Ae. albopictus contributes to DENV transmission and whether an improved understanding of its vector status would enhance dengue surveillance and prevention. To assess the relative public health importance of Ae. albopictus for dengue, we carried out two complementary analyses. We reviewed its role in past dengue epidemics and compared its DENV vector competence with that of Ae. aegypti. Observations from "natural experiments" indicate that, despite seemingly favorable conditions, places where Ae. albopictus predominates over Ae. aegypti have never experienced a typical explosive dengue epidemic with severe cases of the disease. Results from a meta-analysis of experimental laboratory studies reveal that although Ae. albopictus is overall more susceptible to DENV midgut infection, rates of virus dissemination from the midgut to other tissues are significantly lower in Ae. albopictus than in Ae. aegypti. For both indices of vector competence, a few generations of mosquito colonization appear to result in a relative increase of Ae. albopictus susceptibility, which may have been a confounding factor in the literature. Our results lead to the conclusion that Ae. albopictus plays a relatively minor role compared to Ae. aegypti in DENV transmission, at least in part due to differences in host preferences and reduced vector competence. Recent examples of rapid arboviral adaptation to alternative mosquito vectors, however, call for cautious extrapolation of our conclusion. Vector status is a dynamic
Mehta, Sanjay R; Chaillon, Antoine; Gaines, Tommi L; Gonzalez-Zuniga, Patricia E; Stockman, Jamila K; Almanza-Reyes, Horatio; Chavez, Jose Roman; Vera, Alicia; Wagner, Karla D; Patterson, Thomas L; Scott, Brianna; Smith, Davey M; Strathdee, Steffanie A
North Tijuana, Mexico is home to many individuals at high risk for transmitting and acquiring human immunodeficiency virus (HIV). Recently, policy shifts by local government impacted how these individuals were handled by authorities. Here we examined how this affected regional HIV transmission dynamics. HIV pol sequences and associated demographic information were collected from 8 research studies enrolling persons in Tijuana and were used to infer viral transmission patterns. To evaluate the impact of recent policy changes on HIV transmission dynamics, qualitative interviews were performed on a subset of recently infected individuals. Between 2004 and 2016, 288 unique HIV pol sequences were obtained from individuals in Tijuana, including 46.4% from men who have sex with men, 42.1% from individuals reporting transactional sex, and 27.8% from persons who inject drugs (some individuals had >1 risk factor). Forty-two percent of sequences linked to at least 1 other sequence, forming 37 transmission clusters. Thirty-two individuals seroconverted during the observation period, including 8 between April and July 2016. Three of these individuals were putatively linked together. Qualitative interviews suggested changes in policing led individuals to shift locations of residence and injection drug use, leading to increased risk taking (eg, sharing needles). Near real-time molecular epidemiologic analyses identified a cluster of linked transmissions temporally associated with policy shifts. Interviews suggested these shifts may have led to increased risk taking among individuals at high risk for HIV acquisition. With all public policy shifts, downstream impacts need to be carefully considered, as even well-intentioned policies can have major public health consequences. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: firstname.lastname@example.org.
Yerly, S; Rakik, A; Kinloch-de-Loes, S; Erb, P; Vernazza, P; Hirschel, B; Perrin, L
Zidovudine (ZDV) was the most widely used anti-HIV drug between 1987 and 1995, and, as already reported, transmission of ZDV-resistant viruses occurs. Several mutations of the reverse transcriptase gene have been identified; one of them affects the 215 codon and is associated with a high degree of resistance. We have determined, using selective PCR, the prevalence of transmission of 215 mutant isolates in 134 patients with primary HIV infection (PHI) and have identified 8 patients with 215 mutant virus between 1989 and 1995 in Switzerland. Mutant resistant viruses have been isolated from patients treated with most antiviral drugs. A systematic search for mutant viruses may provide useful information for the adaptation of treatment strategies.
Full Text Available Understanding the quantitative characteristics of a pathogen’s capability to transmit during distinct phases of infection is important to enable accurate predictions of the spread and impact of a disease outbreak. In the current investigation, the potential for transmission of foot-and-mouth disease virus (FMDV during the incubation (preclinical phase of infection was investigated in seven groups of pigs that were sequentially exposed to a group of donor pigs that were infected by simulated-natural inoculation. Contact-exposed pigs were co-mingled with infected donors through successive eight-hour time slots spanning from 8 to 64 hours post inoculation (hpi of the donor pigs. The transition from latent to infectious periods in the donor pigs was clearly defined by successful transmission of foot-and-mouth disease (FMD to all contact pigs that were exposed to the donors from 24 hpi and later. This onset of infectiousness occurred concurrent with detection of viremia, but approximately 24 hours prior to the first appearance of clinical signs of FMD in the donors.Thus, the latent period of infection ended approximately 24 hours earlier than the end of the incubation period. There were significant differences between contact-exposed groups in the time elapsed from virus exposure to the first detection of FMDV shedding, viremia and clinical lesions. Specifically, the onset and progression of clinical FMD was more rapid in pigs that had been exposed to the donor pigs during more advanced phases of disease, suggesting that these animals had received a higher effective challenge dose. These results demonstrate transmission and dissemination of FMD within groups of pigs during the incubation period of infection. Furthermore, the findings suggest that under current conditions, shedding of FMDV in oropharyngeal fluids is a more precise proxy for FMDV infectiousness than clinical signs of infection. These findings may impact modeling of the propagation of
Valdazo-González, Begoña; Kim, Jan T; Soubeyrand, Samuel; Wadsworth, Jemma; Knowles, Nick J; Haydon, Daniel T; King, Donald P
Full-genome sequences have been used to monitor the fine-scale dynamics of epidemics caused by RNA viruses. However, the ability of this approach to confidently reconstruct transmission trees is limited by the knowledge of the genetic diversity of viruses that exist within different epidemiological units. In order to address this question, this study investigated the variability of 45 foot-and-mouth disease virus (FMDV) genome sequences (from 33 animals) that were collected during 2007 from eight premises (10 different herds) in the United Kingdom. Bayesian and statistical parsimony analysis demonstrated that these sequences exhibited clustering which was consistent with a transmission scenario describing herd-to-herd spread of the virus. As an alternative to analysing all of the available samples in future epidemics, the impact of randomly selecting one sequence from each of these herds was used to assess cost-effective methods that might be used to infer transmission trees during FMD outbreaks. Using these approaches, 85% and 91% of the resulting topologies were either identical or differed by only one edge from a reference tree comprising all of the sequences generated within the outbreak. The sequence distances that accrued during sequential transmission events between epidemiological units was estimated to be 4.6 nucleotides, although the genetic variability between viruses recovered from chronic carrier animals was higher than between viruses from animals with acute-stage infection: an observation which poses challenges for the use of simple approaches to infer transmission trees. This study helps to develop strategies for sampling during FMD outbreaks, and provides data that will guide the development of further models to support control policies in the event of virus incursions into FMD free countries. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.
Allerson, Matt; Deen, John; Detmer, Susan E; Gramer, Marie R; Joo, Han Soo; Romagosa, Anna; Torremorell, Montserrat
The commonality of influenza A virus (IAV) exposure and vaccination on swine farms in the United States ensures that the majority of neonatal pigs will have some degree of maternal immunity to IAV. The influence of maternal immunity on IAV transmission in neonatal pig populations will impact virus prevalence and infection dynamics across pig populations. The main objective of this study was to assess the impact of maternally derived immunity on IAV transmission in an experimental setting. Neonatal pigs suckled colostrum and derived maternal (passive) immunity from sows in one of three treatment groups: (a) non-vaccinated control (CTRL) or vaccinated with (b) homologous (PASSV-HOM) or (c) heterologous (PASSV-HET) inactivated experimental IAV vaccines. Sentinel neonatal pigs derived from the groups above were challenged with IAV via direct contact with an experimentally infected pig (seeder pig) and monitored for IAV infection daily via nasal swab sampling. A susceptible-infectious-recovered (SIR) experimental model was used to obtain and estimate transmission parameters in each treatment group via a generalized linear model. All sentinel pigs in the CTRL (30/30) and PASSV-HET (30/30) groups were infected with IAV following contact with the seeder pigs and the reproduction ratio estimates (95% confidence interval) were 10.4 (6.6-15.8) and 7.1 (4.2-11.3), respectively. In contrast, 1/20 sentinel pigs in the PASSV-HOM group was infected following contact with the seeder pigs and the reproduction ratio estimate was significantly lower compared to the CTRL and PASSV-HET groups at 0.8 (0.1-3.7). Under the conditions of this study, IAV transmission was reduced in neonatal pigs with homologous maternal immunity compared to seronegative neonatal pigs and pigs with heterologous maternal immunity as defined in this study. This study provides estimates for IAV transmission in pigs with differing types of maternal immunity which may describe the influence of maternal immunity on
Uttenthal, Åse; Høyer, M.J.; Grøndahl, C.
This study investigates the transmission of bovine viral diarrhoea virus (BVDV) 1f from a persistently infected (PI) lesser Malayan mousedeer to two bovine calves. Different contact routes to two calves were analysed: 1) aerosol contact between two adjacent pens without physical contact; 2) indir...... mousedeer BVD virus in the E2 region (420 nucleotides) through 4 generations showed only 7 mutations, which were maintained from mother to offspring....
Manyangarirwa, W.; Sibiya, J.; Mortensen, C A Nieves Paulino
The smallholder farming sector in much of the developing world relies on the use of farm-retained seed. The availability of good quality disease free seed is important in enhancing food security but seed-borne viruses can be a major problem on farm-retained seed. Seeds of tomato (Lycopersicon...... electron microscopy, Enzyme Linked Immunosorbent Assay (ELISA) and biological assays. Tomato mosaic virus (ToMV) was detected in 36% of tomato samples and in 8% of paprika samples using indicator Nicotiana tabacum cultivars Xanthinc and White Burley. Some 43% of cowpea samples were infected with Cowpea...
Completely assembled virus particles detected by transmission electron microscopy in proximal and mid-axons of neurons infected with herpes simplex virus type 1, herpes simplex virus type 2 and pseudorabies virus
Huang Jialing; Lazear, Helen M.; Friedman, Harvey M.
The morphology of alphaherpesviruses during anterograde axonal transport from the neuron cell body towards the axon terminus is controversial. Reports suggest that transport of herpes simplex virus type 1 (HSV-1) nucleocapsids and envelope proteins occurs in separate compartments and that complete virions form at varicosities or axon termini (subassembly transport model), while transport of a related alphaherpesvirus, pseudorabies virus (PRV) occurs as enveloped capsids in vesicles (assembled transport model). Transmission electron microscopy of proximal and mid-axons of primary superior cervical ganglion (SCG) neurons was used to compare anterograde axonal transport of HSV-1, HSV-2 and PRV. SCG cell bodies were infected with HSV-1 NS and 17, HSV-2 2.12 and PRV Becker. Fully assembled virus particles were detected intracellularly within vesicles in proximal and mid-axons adjacent to microtubules after infection with each virus, indicating that assembled virions are transported anterograde within axons for all three alphaherpesviruses.
Have, P; Moving, V; Svansson, V
Antibodies to a transmissible gastroenteritis virus (TGEV)-related coronavirus have been demonstrated in mink sera by indirect immunofluorescence, peroxidase-linked antibody assays and immunoblotting. This is the first serological evidence of a specific coronavirus infection in mink. The putative...
Pascua, Philippe Noriel Q; Song, Min-Suk; Lee, Jun Han; Baek, Yun Hee; Kwon, Hyeok-il; Park, Su-Jin; Choi, Eun Hye; Lim, Gyo-Jin; Lee, Ok-Jun; Kim, Si-Wook; Kim, Chul-Joong; Sung, Moon Hee; Kim, Myung Hee; Yoon, Sun-Woo; Govorkova, Elena A; Webby, Richard J; Webster, Robert G; Choi, Young-Ki
Efficient worldwide swine surveillance for influenza A viruses is urgently needed; the emergence of a novel reassortant pandemic H1N1 (pH1N1) virus in 2009 demonstrated that swine can be the direct source of pandemic influenza and that the pandemic potential of viruses prevalent in swine populations must be monitored. We used the ferret model to assess the pathogenicity and transmissibility of predominant Korean triple-reassortant swine (TRSw) H1N2 and H3N2 influenza viruses genetically related to North American strains. Although most of the TRSw viruses were moderately pathogenic, one [A/Swine/Korea/1204/2009; Sw/1204 (H1N2)] was virulent in ferrets, causing death within 10 d of inoculation, and was efficiently transmitted to naive contact ferrets via respiratory droplets. Although molecular analysis did not reveal known virulence markers, the Sw/1204 virus acquired mutations in hemagglutinin (HA) (Asp-225-Gly) and neuraminidase (NA) (Ser-315-Asn) proteins during the single ferret passage. The contact-Sw/1204 virus became more virulent in mice, replicated efficiently in vitro, extensively infected human lung tissues ex vivo, and maintained its ability to replicate and transmit in swine. Reverse-genetics studies further indicated that the HA(225G) and NA(315N) substitutions contributed substantially in altering virulence and transmissibility. These findings support the continuing threat of some field TRSw viruses to human and animal health, reviving concerns on the capacity of pigs to create future pandemic viruses. Apart from warranting continued and enhanced global surveillance, this study also provides evidence on the emerging roles of HA(225G) and NA(315N) as potential virulence markers in mammals.
Full Text Available Although Newcastle disease virus (NDV with high pathogenicity has frequently been isolated in poultry in China since 1948, the mode of its transmission among avian species remains largely unknown. Given that various wild bird species have been implicated as sources of transmission, in this study we genotypically and pathotypically characterized 23 NDV isolates collected from chickens, ducks, and pigeons in live bird markets (LBMs in South China as part of an H7N9 surveillance program during December 2013–February 2014. To simulate the natural transmission of different kinds of animals in LBMs, we selected three representative NDVs—namely, GM, YF18, and GZ289—isolated from different birds to evaluate the pathogenicity and transmission of the indicated viruses in chickens, ducks, and pigeons. Furthermore, to investigate the replication and shedding of NDV in poultry, we inoculated the chickens, ducks, and pigeons with 106 EID50 of each virus via intraocular and intranasal routes. Eight h after infection, the naïve contact groups were housed with those inoculated with each of the viruses as a means to monitor contact transmission. Our results indicated that genetically diverse viruses circulate in LBMs in South China’s Guangdong Province and that NDV from different birds have different tissue tropisms and host ranges when transmitted in different birds. We therefore propose the continuous epidemiological surveillance of LBMs to support the prevention of the spread of these viruses in different birds, especially chickens, and highlight the need for studies of the virus–host relationship.
Full Text Available Viruses occurring in Serbia and other countries in the region are a huge problem constrainingseed potato production. At lower altitudes, in lowland and hilly regions, wheretable potato production is widely distributed, more than 50% of healthy plants becomeinfected with potato virus Y during one growing season. Under these conditions, seed potatoproduction is hindered due to a high infection pressure of potato virus Y which spreads farmore rapidly compared to leaf roll virus, virus S and other viruses hosted by this plant species.This study tended to clarify a frequent dilemma regarding the use of insecticides in preventingthe infection of healthy plants with potato virus Y and leaf roll virus, given the oraland written recommendations from pesticide manufacturers, agronomists and scientistsin the field of crop protection arising from a logical conclusion that aphid vector controlresults in virus transmission control.The present findings, which are in agreement with reports of authors from other countries,show that the use of insecticides is ineffective in preventing potato virus Y which isnonpersistently transmitted by aphids from an external source of infection.However, insecticides can exhibit efficacy in preventing potato virus Y transmissionfrom infected plants to healthy plants within a crop, which can have an overall positiveeffect only if seed potato is grown in areas that have no external source of infection.The present results and those of other authors show that insecticides are effective inpreventing the infection of healthy plants with persistently transmitted leaf roll virus.Mineral oils provide effective control of potato virus Y by preventing the infection ofpotato plants with the virus. They can be combined with other management practices toprotect seed potato crops against the virus.Given the fact that the initial first-year infection of healthy potato plants with virus Y inrelation to leaf roll virus is approximately 10
Faye, Ousmane; Boëlle, Pierre-Yves; Heleze, Emmanuel; Faye, Oumar; Loucoubar, Cheikh; Magassouba, N’Faly; Soropogui, Barré; Keita, Sakoba; Gakou, Tata; Bah, El Hadji Ibrahima; Koivogui, Lamine; Sall, Amadou Alpha; Cauchemez, Simon
Background An Ebola Virus Disease (EVD) epidemic of unprecedented magnitude is ongoing in West Africa, affecting for the first time large urban centers like Conakry, the capital of Guinea. Methods Interviews of EVD patients, relatives and neighbors and laboratory databases were used to reconstruct EVD chains of transmission in Conakry, from March to August 2014. Findings Out of 193 confirmed and probable EVD cases reported in Conakry, Boffa and Télimélé, 152 (79%) were positioned in the chains of transmission. In March, non-Health Care Workers cases infected on average 2.3 (95% CI: 1.6, 3.2) persons, breaking down into 1.4 (95% CI: 0.9, 2.2) persons in the community, 0.4 (95% CI: 0.1, 0.9) in the hospital and 0.5 (95% CI: 0.2, 1.0) at funerals. Following implementation of infection control in April, the reproduction number in the hospital and at funerals reduced below 0.1. In the community, the reproduction number, which was positively correlated with patients viremia, dropped by 50% for hospitalized cases but remained unchanged for those not hospitalized. Hospital and funeral transmission represented 35% (7/20) and 15% (3/20) of all transmissions in March; but only 9% (11/128) and 4% (5/128) from April onward. Overall, 82% (119/145) of transmission occurred in the community and 72% (105/145) between family members. Simulations showed that a 10% increase in hospitalizations could have reduced the length of chains by 26% (95% CI: 4%, 45%). Interpretation Monitoring chains of transmission is critical to evaluate and optimize local control strategies for EVD. In Conakry, interventions had the potential to stop the epidemic but reintroductions of the disease and lack of cooperation of a small number of families led to prolonged low-level spread, highlighting challenges of EVD control in large urban centers. Funding Labex IBEID, Reacting, PREDEMICS, NIGMS MIDAS initiative, Institut Pasteur de Dakar. PMID:25619149
Tovo, Pier-Angelo; Calitri, Carmelina; Scolfaro, Carlo; Gabiano, Clara; Garazzino, Silvia
The worldwide prevalence of hepatitis C virus (HCV) infection in children is 0.05%-0.4% in developed countries and 2%-5% in resource-limited settings, where inadequately tested blood products or un-sterile medical injections still remain important routes of infection. After the screening of blood donors, mother-to-child transmission (MTCT) of HCV has become the leading cause of pediatric infection, at a rate of 5%. Maternal HIV co-infection is a significant risk factor for MTCT and anti-HIV therapy during pregnancy seemingly can reduce the transmission rate of both viruses. Conversely, a high maternal viral load is an important, but not preventable risk factor, because at present no anti-HCV treatment can be administered to pregnant women to block viral replication. Caution is needed in adopting obstetric procedures, such as amniocentesis or internal fetal monitoring, that can favor fetal exposure to HCV contaminated maternal blood, though evidence is lacking on the real risk of single obstetric practices. Mode of delivery and type of feeding do not represent significant risk factors for MTCT. Therefore, there is no reason to offer elective caesarean section or discourage breast-feeding to HCV infected parturients. Information on the natural history of vertical HCV infection is limited. The primary infection is asymptomatic in infants. At least one quarter of infected children shows a spontaneous viral clearance (SVC) that usually occurs within 6 years of life. IL-28B polymorphims and genotype 3 infection have been associated with greater chances of SVC. In general, HCV progression is mild or moderate in children with chronic infection who grow regularly, though cases with marked liver fibrosis or hepatic failure have been described. Non-organ specific autoantibodies and cryoglobulins are frequently found in children with chronic infection, but autoimmune diseases or HCV associated extrahepatic manifestations are rare.
Fry, Craig L; Lintzeris, Nick
To develop a standard measure of blood-borne virus transmission risk behaviour, and examine the underlying psychometric properties. The Blood-borne Virus Transmission Risk Assessment Questionnaire (BBV-TRAQ) was developed over three consecutive phases of the original BBV-TRAQ study in adherence to classical scale development procedures, culminating in the recruitment of a development sample of current injecting drug users via convenience and snowball sampling. Needle and syringe programmes (NSPs), medical clinics, alcohol/drug agencies, peer-based and outreach organizations across inner and outer metropolitan Melbourne. Two hundred and nine current injecting drug users. The mean age was 27 years, 68% were male, 65% unemployed, 36% with prison history and 25% in methadone maintenance. BBV-TRAQ items cover specific injecting, sexual and skin penetration risk practices. BBV-TRAQ characteristics were assessed via measures of internal and test-retest reliability; collateral validation; and principal components analyses. The BBV-TRAQ has satisfactory psychometric properties. Internal (a=0.87), test-retest (r=0.84) and inter-observer reliability results were high, suggesting that the instrument provides a reliable measure of BBV risk behaviour and is reliable over time and across interviewers. A principal components analysis with varimax rotation produced a parsimonious factor solution despite modest communality, and indicated that three factors (injecting, sex and skin penetration/hygiene risks) are required to describe BBV risk behaviour. The BBV-TRAQ is reliable and represents the first risk assessment tool to incorporate sufficient coverage of injecting, sex and other skin penetration risk practices to be considered truly content valid. The questionnaire is indicated for use in addictions research, clinical, peer education and BBV risk behaviour surveillance settings.
Faye, Ousmane; Boëlle, Pierre-Yves; Heleze, Emmanuel; Faye, Oumar; Loucoubar, Cheikh; Magassouba, N'Faly; Soropogui, Barré; Keita, Sakoba; Gakou, Tata; Bah, El Hadji Ibrahima; Koivogui, Lamine; Sall, Amadou Alpha; Cauchemez, Simon
An epidemic of Ebola virus disease of unprecedented size continues in parts of west Africa. For the first time, large urban centres such as Conakry, the capital of Guinea, are affected. We did an observational study of patients with Ebola virus disease in three regions of Guinea, including Conakry, aiming to map the routes of transmission and assess the effect of interventions. Between Feb 10, 2014, and Aug 25, 2014, we obtained data from the linelist of all confirmed and probable cases in Guinea (as of Sept 16, 2014), a laboratory database of information about patients, and interviews with patients and their families and neighbours. With this information, we mapped chains of transmission, identified which setting infections most probably originated from (community, hospitals, or funerals), and computed the context-specific and overall reproduction numbers. Of 193 confirmed and probable cases of Ebola virus disease reported in Conakry, Boffa, and Télimélé, 152 (79%) were positioned in chains of transmission. Health-care workers contributed little to transmission. In March, 2014, individuals with Ebola virus disease who were not health-care workers infected a mean of 2·3 people (95% CI 1·6-3·2): 1·4 (0·9-2·2) in the community, 0·4 (0·1-0·9) in hospitals, and 0·5 (0·2-1·0) at funerals. After the implementation of infection control in April, the reproduction number in hospitals and at funerals reduced to lower than 0·1. In the community, the reproduction number dropped by 50% for patients that were admitted to hospital, but remained unchanged for those that were not. In March, hospital transmissions constituted 35% (seven of 20) of all transmissions and funeral transmissions constituted 15% (three); but from April to the end of the study period, they constituted only 9% (11 of 128) and 4% (five), respectively. 82% (119 of 145) of transmission occurred in the community and 72% (105) between family members. Our simulations show that a 10% increase in
Combs, C Andrew; Fishman, Alan
Three steps must be followed to prevent the transmission of infection via a contaminated transvaginal ultrasound probe: cleaning the probe after every use, high-level disinfection, and covering the probe with a single-use barrier during the examination. There may be critical flaws in at least 2 of these steps as they are currently practiced. First, 2 widely used disinfectants, glutaraldehyde and orthophthalaldehyde, have recently been found to be ineffective at neutralizing human papilloma virus type 16 and type 18. Second, commercial ultrasound probe covers have an unacceptable rate of leakage (8-81%) compared to condoms (0.9-2%). We recommend the use of a sonicated hydrogen peroxide disinfectant system rather than aldehyde-type disinfectants. We recommend that the probe be covered with a condom rather than a commercial probe cover during transvaginal ultrasound examination. Combined with probe cleaning, these 2 steps are estimated to result in an 800 million- to 250 billion-fold reduction in human papilloma virus viral load, which should translate to greatly enhanced patient safety. Copyright © 2016 Elsevier Inc. All rights reserved.
Jia, Haimei; Zhang, Meng; Chen, Maoyu; Yang, Zhiwen; Li, Jiansen; Huang, Guo; Guan, Dawei; Cen, Xiaoli; Zhang, Lijie; Feng, Qiwen; Yi, Jianron; Wu, De; Zhong, Haojie; Ma, Huilai; Song, Tie
Zika virus (ZIKV) is a mosquito-borne virus spreading rapidly in the Americas, Africa, and Asia. No indigenous ZIKV infection had been seen in China. We monitored ZIKV infection among travelers returning to Enping county from ZIKV transmitting countries from 1 March to 10 April 2016. We analyzed data including interviews; conducted laboratory test on blood, urine, saliva, conjunctival swab or semen specimens for evidence of ZIKV infection; evaluated household for presence of Aedes mosquitoes or larvae. A total of 925 individuals were screened, 507 (54.8%) were interviewed, 400 (43.2%) provided samples, of which 13 (3.3%) tested positive for ZIKV including 3 asymptomatic. Rash, conjunctivitis, sore throat, fever were the common symptoms; rash was more pronounced in adults than in children. ZIKV RNA was detected for 1-4 days in blood, but longer in urine and saliva (3-32 days and 2-10 days). Among interviewed, 57.0% had good knowledge about ZIKV, 45.8% were worried about ZIKV, 99.2% would go to hospital if they had infection. Aedes mosquitoes or larvae were detected in townships of infected returners. ZIKV was imported to China. Screening by symptoms alone is inadequate for detecting ZIKV infection. ZIKV surveillance, health-education, and vector control are necessary to decrease risk of ZIKV transmission. Copyright © 2017. Published by Elsevier Ltd.
Haryadi, D; Verreth, J A J; Verdegem, M C J; Vlak, J M
Dendronereis spp. (Peters) (Nereididae) is a common polychaete in shrimp ponds built on intertidal land and is natural food for shrimp in traditionally managed ponds in Indonesia. White spot syndrome virus (WSSV), an important viral pathogen of the shrimp, can replicate in this polychaete (Desrina et al. 2013); therefore, it is a potential propagative vector for virus transmission. The major aim of this study was to determine whether WSSV can be transmitted from naturally infected Dendronereis spp. to specific pathogen-free (SPF) Pacific white shrimp Litopenaeus vannamei (Boone) through feeding. WSSV was detected in naturally infected Dendronereis spp. and Penaeus monodon Fabricius from a traditional shrimp pond, and the positive animals were used in the current experiment. WSSV-infected Dendronereis spp. and P. monodon in a pond had a point prevalence of 90% and 80%, respectively, as measured by PCR. WSSV was detected in the head, gills, blood and mid-body of Dendronereis spp. WSSV from naturally infected Dendronereis spp was transmitted to SPF L. vannamei and subsequently from this shrimp to new naïve-SPF L. vannamei to cause transient infection. Our findings support the contention that Dendronereis spp, upon feeding, can be a source of WSSV infection of shrimp in ponds. © 2014 John Wiley & Sons Ltd.
Wang, Xiaoqing; Hu, Weiwei; Zhu, Liqi; Yang, Qian
Intestinal epithelial cells are the targets for transmissible gastroenteritis (TGE) virus (TGEV) infection. It is urgent to develop a novel candidate against TGEV entry. Bacillus subtilis is a probiotic with excellent anti-microorganism properties and one of its secretions, surfactin, has been regarded as a versatile weapon for most plant pathogens, especially for the enveloped virus. We demonstrate for the first time that B. subtilis OKB105 and its surfactin can effectively inhibit one animal coronavirus, TGEV, entering the intestinal porcine epithelial cell line (IPEC-J2). Then, several different experiments were performed to seek the might mechanisms. The plaque assays showed that surfactant could reduce the plaque generation of TGEV in a dose-dependent manner. Meanwhile, after incubation with TGEV for 1.5 h, B. subtilis could attach TGEV particles to their surface so that the number of virus to bind to the host cells was declined. Furthermore, our data showed that the inhibition of B. subtilis was closely related to the competition with TGEV for the viral entry receptors, including epidermal growth factor receptor (EGFR) and aminopeptidase N (APN) protein. In addition, Western blotting and apoptosis analysis indicated that B. subtilis could enhance the resistance of IPEC-J2 cells by up-regulating the expression of toll-like receptor (TLR)-6 and reducing the percentage of apoptotic cells. Taken together, our results suggest that B. subtilis OKB105 and its surfactin can antagonize TGEV entry in vitro and may serve as promising new candidates for TGEV prevention. © 2017 The Author(s).
Full Text Available Summary: Objectives: The 2009 pandemic influenza A (H1N1 virus is a public health challenge. Notably, laboratory-confirmed cases do not represent the age group most susceptible to infection. To characterize the age distribution of all cases of H1N1 influenza, we studied the personal contacts of confirmed cases to identify the age group at the highest risk. Methods: We investigated the family members of 162 laboratory-confirmed cases of 2009 H1N1 in Yazd, Iran. Family members were retrospectively asked whether they had ≥2 respiratory symptoms within 7 days of the last contact with the associated index cases. The ages and symptoms of the patients as well as the interval between diagnosis and the onset of symptoms among household contacts were determined using a questionnaire. Results: We identified 596 family members of index cases, 83 (13.9% of whom developed acute respiratory illness. No acute respiratory illness was found in 104 families (64%; however, there were 2 cases in 15 families (9.3% and ≥3 cases in 4 families (24%. Household contacts from 5 to 18 years old were more susceptible to acute respiratory illness than those who were ≥51 years old (RR = 3.174, 95% CI 1.313–7.675 P-value = 0.01. Conclusion: Individuals ≤18 years old were most susceptible to infection by the H1N1 virus. Therefore, in low-income populations, prevention of the spread of H1N1 to this age group should be emphasized. Keywords: Household transmission, 2009 Influenza A (H1N1 virus
Kanakala, Surapathrudu; Ghanim, Murad
Tomato yellow leaf curl virus (TYLCV) is a single-stranded (ssDNA) begomoviruses that causes severe damage to tomato and several other crops worldwide. TYLCV is exclusively transmitted by the sweetpotato whitefly, Bemisia tabaci in a persistent circulative and propagative manner. Previous studies have shown that the transmission, retention, and circulation of TYLCV in its vector involves interaction with insect and endosymbiont proteins, which aid in the transmission of the virus, or have a protective role in response to the presence of the virus in the insect body. However, only a low number of such proteins have been identified. Here, the role of B. tabaci Cyclophilin B (CypB) in the transmission of TYLCV protein was investigated. Cyclophilins are a large family of cellular prolyl isomerases that have many molecular roles including facilitating protein-protein interactions in the cell. One cyclophilin protein has been implicated in aphid-luteovirus interactions. We demonstrate that the expression of CypB from B. tabaci is altered upon TYLCV acquisition and retention. Further experiments used immunocapture-PCR and co-immunolocalization and demonstrated a specific interaction and colocalization between CypB and TYLCV in the the midgut, eggs, and salivary glands. Membrane feeding of anti-CypB antibodies and TYLCV-infected plants showed a decrease in TYLCV transmission, suggesting a critical role that CypB plays in TYLCV transmission. Further experiments, which used membrane feeding with the CypB inhibitor Cyclosporin A showed decrease in CypB-TYLCV colocalization in the midgut and virus transmission. Altogether, our results indicate that CypB plays an important role in TYLCV transmission by B. tabaci .
Full Text Available Tomato yellow leaf curl virus (TYLCV is a single-stranded (ssDNA begomoviruses that causes severe damage to tomato and several other crops worldwide. TYLCV is exclusively transmitted by the sweetpotato whitefly, Bemisia tabaci in a persistent circulative and propagative manner. Previous studies have shown that the transmission, retention and circulation of TYLCV in its vector involves interaction with insect and endosymbiont proteins, which aid in the transmission of the virus, or have a protective role in response to the presence of the virus in the insect body. However, only a low number of such proteins have been identified. Here, the role of B. tabaci Cyclophilin B (CypB in the transmission of TYLCV protein was investigated. Cyclophilins (Cyps are a large family of cellular prolyl isomerases that have many molecular roles including facilitating protein-protein interactions in the cell. One cyclophilin protein has been implicated in aphid-luteovirus interactions. We demonstrate that the expression of CypB from B. tabaci is altered upon TYLCV acquisition and retention. Further experiments used immunocapture-PCR and co-immunolocalization and demonstrated a specific interaction and colocalization between CypB and TYLCV in the the midgut, eggs and salivary glands. Membrane feeding of anti-CypB antibodies and TYLCV infected plants showed a decrease in TYLCV transmission, suggesting a critical role that CypB plays in TYLCV transmission. Further experiments, which used membrane feeding with the CypB inhibitor Cyclosporin A (CsA showed decrease in CypB-TYLCV colocalization in the midgut and virus transmission. Altogether, our results indicate that CypB plays an important role in TYLCV transmission by B. tabaci.
Sobel Leonard, Ashley; Weissman, Daniel B; Greenbaum, Benjamin; Ghedin, Elodie; Koelle, Katia
The bottleneck governing infectious disease transmission describes the size of the pathogen population transferred from the donor to the recipient host. Accurate quantification of the bottleneck size is particularly important for rapidly evolving pathogens such as influenza virus, as narrow bottlenecks reduce the amount of transferred viral genetic diversity and, thus, may decrease the rate of viral adaptation. Previous studies have estimated bottleneck sizes governing viral transmission by using statistical analyses of variants identified in pathogen sequencing data. These analyses, however, did not account for variant calling thresholds and stochastic viral replication dynamics within recipient hosts. Because these factors can skew bottleneck size estimates, we introduce a new method for inferring bottleneck sizes that accounts for these factors. Through the use of a simulated data set, we first show that our method, based on beta-binomial sampling, accurately recovers transmission bottleneck sizes, whereas other methods fail to do so. We then apply our method to a data set of influenza A virus (IAV) infections for which viral deep-sequencing data from transmission pairs are available. We find that the IAV transmission bottleneck size estimates in this study are highly variable across transmission pairs, while the mean bottleneck size of 196 virions is consistent with a previous estimate for this data set. Furthermore, regression analysis shows a positive association between estimated bottleneck size and donor infection severity, as measured by temperature. These results support findings from experimental transmission studies showing that bottleneck sizes across transmission events can be variable and influenced in part by epidemiological factors. IMPORTANCE The transmission bottleneck size describes the size of the pathogen population transferred from the donor to the recipient host and may affect the rate of pathogen adaptation within host populations. Recent
Margaria, P; Bosco, L; Vallino, M; Ciuffo, M; Mautino, G C; Tavella, L; Turina, M
Tomato spotted wilt virus (TSWV) is the type member of tospoviruses (genus Tospovirus), plant-infecting viruses that cause severe damage to ornamental and vegetable crops. Tospoviruses are transmitted by thrips in the circulative propagative mode. We generated a collection of NSs-defective TSWV isolates and showed that TSWV coding for truncated NSs protein could not be transmitted by Frankliniella occidentalis. Quantitative reverse transcription (RT)-PCR and immunostaining of individual insects detected the mutant virus in second-instar larvae and adult insects, demonstrating that insects could acquire and accumulate the NSs-defective virus. Nevertheless, adults carried a significantly lower viral load, resulting in the absence of transmission. Genome sequencing and analyses of reassortant isolates showed genetic evidence of the association between the loss of competence in transmission and the mutation in the NSs coding sequence. Our findings offer new insight into the TSWV-thrips interaction and Tospovirus pathogenesis and highlight, for the first time in the Bunyaviridae family, a major role for the S segment, and specifically for the NSs protein, in virulence and efficient infection in insect vector individuals. Our work is the first to show a role for the NSs protein in virus accumulation in the insect vector in the Bunyaviridae family: demonstration was obtained for the system TSWV-F. occidentalis, arguably one of the most damaging combination for vegetable crops. Genetic evidence of the involvement of the NSs protein in vector transmission was provided with multiple approaches.
Pulit-Penaloza, Joanna A; Jones, Joyce; Sun, Xiangjie; Jang, Yunho; Thor, Sharmi; Belser, Jessica A; Zanders, Natosha; Creager, Hannah M; Ridenour, Callie; Wang, Li; Stark, Thomas J; Garten, Rebecca; Chen, Li-Mei; Barnes, John; Tumpey, Terrence M; Wentworth, David E; Maines, Taronna R; Davis, C Todd
Influenza A(H1) viruses circulating in swine represent an emerging virus threat, as zoonotic infections occur sporadically following exposure to swine. A fatal infection caused by an H1N1 variant (H1N1v) virus was detected in a patient with reported exposure to swine and who presented with pneumonia, respiratory failure, and cardiac arrest. To understand the genetic and phenotypic characteristics of the virus, genome sequence analysis, antigenic characterization, and ferret pathogenesis and transmissibility experiments were performed. Antigenic analysis of the virus isolated from the fatal case, A/Ohio/09/2015, demonstrated significant antigenic drift away from the classical swine H1N1 variant viruses and H1N1 pandemic 2009 viruses. A substitution in the H1 hemagglutinin (G155E) was identified that likely impacted antigenicity, and reverse genetics was employed to understand the molecular mechanism of antibody escape. Reversion of the substitution to 155G, in a reverse genetics A/Ohio/09/2015 virus, showed that this residue was central to the loss of hemagglutination inhibition by ferret antisera raised against a prototypical H1N1 pandemic 2009 virus (A/California/07/2009), as well as gamma lineage classical swine H1N1 viruses, demonstrating the importance of this residue for antibody recognition of this H1 lineage. When analyzed in the ferret model, A/Ohio/09/2015 and another H1N1v virus, A/Iowa/39/2015, as well as A/California/07/2009, replicated efficiently in the respiratory tract of ferrets. The two H1N1v viruses transmitted efficiently among cohoused ferrets, but respiratory droplet transmission studies showed that A/California/07/2009 transmitted through the air more efficiently. Preexisting immunity to A/California/07/2009 did not fully protect ferrets from challenge with A/Ohio/09/2015. IMPORTANCE Human infections with classical swine influenza A(H1N1) viruses that circulate in pigs continue to occur in the United States following exposure to swine. To
Leder, Karin; Grobusch, Martin P.; Gautret, Philippe; Chen, Lin H.; Kuhn, Susan; Lim, Poh Lian; Yates, Johnnie; McCarthy, Anne E.; Rothe, Camilla; Kato, Yasuyuki; Bottieau, Emmanuel; Huber, Kristina; Schwartz, Eli; Stauffer, William; Malvy, Denis; Shaw, Marc T. M.; Rapp, Christophe; Blumberg, Lucille; Jensenius, Mogens; van Genderen, Perry J. J.; Hamer, Davidson H.
Zika virus (ZIKV) was first isolated in Africa; decades later, caused large outbreaks in the Pacific, and is considered endemic in Asia. We aim to describe ZIKV disease epidemiology outside the Americas, the importance of travelers as sentinels of disease transmission, and discrepancies in travel
Wheat streak mosaic virus (WSMV; genus Tritimovirus; family Potyviridae), is transmitted by the wheat curl mite (Aceria tosichella Keifer). The requirement of coat protein (CP) for WSMV transmission by the wheat curl mite was examined using a series of viable deletion and point mutations. Mite trans...
Roussel, Marion; Pontier, Dominique; Ngoubangoye, Barthélémy; Kazanji, Mirdad; Verrier, Delphine; Fouchet, David
Non-human primates (NHPs) often live in inaccessible areas, have cryptic behaviors, and are difficult to follow in the wild. Here, we present a study on the spread of the simian T-lymphotropic Virus Type 1 (STLV-1), the simian counterpart of the human T-lymphotropic virus type 1 (HTLV-1) in a semi-captive mandrill colony. This study combines 28 years of longitudinal monitoring, including behavioral data, with a dynamic mathematical model and Bayesian inference. Three transmission modes were suspected: aggressive, sexual and familial. Our results show that among males, STLV-1 transmission occurs preferentially via aggression. Because of their impressive aggressive behavior male mandrills can easily transmit the virus during fights. On the contrary, sexual activity seems to have little effect. Thus transmission appears to occur primarily via male-male and female-female contact. In addition, for young mandrills, familial transmission appears to play an important role in virus spread. Copyright © 2015 Elsevier B.V. All rights reserved.
Gonzales, J.L.; Elbers, A.R.W.; Goot, van der J.A.; Bontje, D.M.; Koch, G.; Wit, de J.J.; Stegeman, J.A.
Even though low pathogenic avian influenza viruses (LPAIv) affect the poultry industry of several countries in the world, information about their transmission characteristics in poultry is sparse. Outbreak reports of LPAIv in layer chickens have described drops in egg production that appear to be
Suryaprasad, A; Basavaraju, S V; Hocevar, S N; Theodoropoulos, N; Zuckerman, R A; Hayden, T; Forbi, J C; Pegues, D; Levine, M; Martin, S I; Kuehnert, M J; Blumberg, E A
Nucleic acid testing (NAT) for hepatitis C virus (HCV) is recommended for screening of organ donors, yet not all donor infections may be detected. We describe three US clusters of HCV transmission from donors at increased risk for HCV infection. Donor's and recipients' medical records were reviewed. Newly infected recipients were interviewed. Donor-derived HCV infection was considered when infection was newly detected after transplantation in recipients of organs from increased risk donors. Stored donor sera and tissue samples were tested for HCV RNA with high-sensitivity quantitative PCR. Posttransplant and pretransplant recipient sera were tested for HCV RNA. Quasispecies analysis of hypervariable region-1 was used to establish genetic relatedness of recipient HCV variants. Each donor had evidence of injection drug use preceding death. Of 12 recipients, 8 were HCV-infected-6 were newly diagnosed posttransplant. HCV RNA was retrospectively detected in stored samples from donor immunologic tissue collected at organ procurement. Phylogenetic analysis showed two clusters of closely related HCV variants from recipients. These investigations identified the first known HCV transmissions from increased risk organ donors with negative NAT screening, indicating very recent donor infection. Recipient informed consent and posttransplant screening for blood-borne pathogens are essential when considering increased risk donors. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.
Domier, L L; Latorre, I J; Steinlage, T A; McCoppin, N; Hartman, G L
The variability of North American and Asian strains and isolates of Soybean mosaic virus was investigated. First, polymerase chain reaction (PCR) products representing the coat protein (CP)-coding regions of 38 SMVs were analyzed for restriction fragment length polymorphisms (RFLP). Second, the nucleotide and predicted amino acid sequence variability of the P1-coding region of 18 SMVs and the helper component/protease (HC/Pro) and CP-coding regions of 25 SMVs were assessed. The CP nucleotide and predicted amino acid sequences were the most similar and predicted phylogenetic relationships similar to those obtained from RFLP analysis. Neither RFLP nor sequence analyses of the CP-coding regions grouped the SMVs by geographical origin. The P1 and HC/Pro sequences were more variable and separated the North American and Asian SMV isolates into two groups similar to previously reported differences in pathogenic diversity of the two sets of SMV isolates. The P1 region was the most informative of the three regions analyzed. To assess the biological relevance of the sequence differences in the HC/Pro and CP coding regions, the transmissibility of 14 SMV isolates by Aphis glycines was tested. All field isolates of SMV were transmitted efficiently by A. glycines, but the laboratory isolates analyzed were transmitted poorly. The amino acid sequences from most, but not all, of the poorly transmitted isolates contained mutations in the aphid transmission-associated DAG and/or KLSC amino acid sequence motifs of CP and HC/Pro, respectively.
Loes C Soetens
Full Text Available Reported acute hepatitis B incidence in the Netherlands reached its nadir in 2013. However, regional signals about increased number of hepatitis B cases raised the question how hepatitis B incidence was distributed over the country. In this study, regional differences in hepatitis B epidemiology were investigated using epidemiological and molecular data.Acute hepatitis B virus (HBV infections, reported between 2009-2013, were included. If serum was available, a fragment of S and C gene of the HBV was amplified and sequenced. Regional differences in incidence were studied by geographical mapping of cases and cluster analysis. Regional differences in transmission were studied by constructing regional maximum parsimony trees based on the C gene to assess genetic clustering of cases.Between 2009 and 2013, 881 cases were notified, of which respectively 431 and 400 cases had serum available for S and C gene sequencing. Geographical mapping of notified cases revealed that incidences in rural border areas of the Netherlands were highest. Cluster analysis identified two significant clusters (p<0.000 in the South-western and North-eastern regions. Genetic cluster analysis showed that rural border areas had relatively large clusters of cases with indistinguishable sequences, while other regions showed more single introductions.This study showed that regional differences in HBV epidemiology were present in the Netherlands. Rural border regions showed higher incidences and more ongoing transmission, mainly among MSM, than the more urban inland areas. Therefore, preventive measures should be enhanced in these regions.
The concept of tertiary sexual transmission of human immunodeficiency virus (HIV) has been central to government efforts to communicate notions of risk to heterosexuals in Australia. Data on heterosexually transmitted acquired immune deficiency syndrome (AIDS) and HIV for Australia are reviewed with emphasis given to the probability of misclassification bias in the heterosexually acquired and 'other/undetermined' categories. Tertiary cases are almost certainly rare in Australia, with little evidence of any increase in their incidence since the first cases were recorded. Three factors (low probability of exposure, the infectivity of HIV and a comparatively low rate of sexual partner change) make it improbable that Australian heterosexuals with no risk factors will experience endemic HIV infection, with a caveat to this conclusion lying in the potential of Australian sex tourism to Southeast Asia for introducing HIV into the Australian heterosexual population. Four hegemonic factors which have acted to suppress any serious debate of the notion that HIV in Australia is unlikely to become endemic among heterosexuals are discussed: the political 'democratization' of risk inspired by concerns that gay men should not be further vilified as a victim group; the preventive imperative; a reluctance among health educators to question the very foundations of the message they are employed to deliver; and a reluctance to curtail 'Trojan horse' benefits to sexually transmissible disease prevention engendered by HIV education promoting safe sex messages.
Morrison, Amy C.; Forshey, Brett M.; Notyce, Desiree; Astete, Helvio; Lopez, Victor; Rocha, Claudio; Carrion, Rebecca; Carey, Cristhiam; Eza, Dominique; Montgomery, Joel M.; Kochel, Tadeusz J.
Enzootic strains of Venezuelan equine encephalitis virus (VEEV) have been isolated from febrile patients in the Peruvian Amazon Basin at low but consistent levels since the early 1990s. Through a clinic-based febrile surveillance program, we detected an outbreak of VEEV infections in Iquitos, Peru, in the first half of 2006. The majority of these patients resided within urban areas of Iquitos, with no report of recent travel outside the city. To characterize the risk factors for VEEV infection within the city, an antibody prevalence study was carried out in a geographically stratified sample of urban areas of Iquitos. Additionally, entomological surveys were conducted to determine if previously incriminated vectors of enzootic VEEV were present within the city. We found that greater than 23% of Iquitos residents carried neutralizing antibodies against VEEV, with significant associations between increased antibody prevalence and age, occupation, mosquito net use, and overnight travel. Furthermore, potential vector mosquitoes were widely distributed across the city. Our results suggest that while VEEV infection is more common in rural areas, transmission also occurs within urban areas of Iquitos, and that further studies are warranted to identify the precise vectors and reservoirs involved in urban VEEV transmission. PMID:19079600
Hu, Wenbiao; Clements, Archie; Williams, Gail; Tong, Shilu; Mengersen, Kerrie
This study aims to examine the impact of socio-ecologic factors on the transmission of Ross River virus (RRV) infection and to identify areas prone to social and ecologic-driven epidemics in Queensland, Australia. We used a Bayesian spatiotemporal conditional autoregressive model to quantify the relationship between monthly variation of RRV incidence and socio-ecologic factors and to determine spatiotemporal patterns. Our results show that the average increase in monthly RRV incidence was 2.4% (95% credible interval (CrI): 0.1–4.5%) and 2.0% (95% CrI: 1.6–2.3%) for a 1°C increase in monthly average maximum temperature and a 10 mm increase in monthly average rainfall, respectively. A significant spatiotemporal variation and interactive effect between temperature and rainfall on RRV incidence were found. No association between Socio-economic Index for Areas (SEIFA) and RRV was observed. The transmission of RRV in Queensland, Australia appeared to be primarily driven by ecologic variables rather than social factors. PMID:20810846
German, Matthew; Creatore, Maria I.; Brent, Shannon; Watts, Alexander G.; Hay, Simon I.; Kulkarni, Manisha A.; Brownstein, John S.; Khan, Kamran
Summary Background As the epidemic of Zika virus expands in the Americas, countries across Africa and the Asia-Pacific region are becoming increasingly susceptible to the importation and possible local spread of the virus. To support public health readiness, we aim to identify regions and times where the potential health, economic, and social effects from Zika virus are greatest, focusing on resource-limited countries in Africa and the Asia-Pacific region. Methods Our model combined transportation network analysis, ecological modelling of mosquito occurrences, and vector competence for flavivirus transmission, using data from the International Air Transport Association, entomological observations from Zika’s primary vector species, and climate conditions using WorldClim. We overlaid monthly flows of airline travellers arriving to Africa and the Asia-Pacific region from areas of the Americas suitable for year-round transmission of Zika virus with monthly maps of climatic suitability for mosquito-borne transmission of Zika virus within Africa and the Asia-Pacific region. Findings An estimated 2·6 billion people live in areas of Africa and the Asia-Pacific region where the presence of competent mosquito vectors and suitable climatic conditions could support local transmission of Zika virus. Countries with large volumes of travellers arriving from Zika affected areas of the Americas and large populations at risk of mosquito-borne Zika virus infection include, India (67 422 travellers arriving per year; 1·2 billion residents in potential Zika transmission areas), China (238 415 travellers; 242 million residents), Indonesia (13 865 travellers; 197 million residents), Philippines (35 635 travellers; 70 million residents), and Thailand (29 241 travellers; 59 million residents). Interpretation Many countries across Africa and the Asia-Pacific region are vulnerable to Zika virus. Strategic use of available health and human resources is essential to prevent or mitigate
Full Text Available Relationships between agents in multitrophic systems are complex and very specific. Insect-transmitted plant viruses are completely dependent on the behaviour and distribution patterns of their vectors. The presence of natural enemies may directly affect aphid behaviour and spread of plant viruses, as the escape response of aphids might cause a potential risk for virus dispersal. The spatio-temporal dynamics of Cucumber mosaic virus (CMV and Cucurbit aphid-borne yellows virus (CABYV, transmitted by Aphis gossypii in a non-persistent and persistent manner, respectively, were evaluated at short and long term in the presence and absence of the aphid parasitoid, Aphidius colemani. SADIE methodology was used to study the distribution patterns of both the virus and its vector, and their degree of association. Results suggested that parasitoids promoted aphid dispersion at short term, which enhanced CMV spread, though consequences of parasitism suggest potential benefits for disease control at long term. Furthermore, A. colemani significantly limited the spread and incidence of the persistent virus CABYV at long term. The impact of aphid parasitoids on the dispersal of plant viruses with different transmission modes is discussed.
Litster, Annette L
Conflicting accounts have been published in the veterinary literature regarding transmission of feline immunodeficiency virus (FIV) between cohabiting cats in mixed households, and the mechanics of possible casual transmission, if it occurs, are poorly understood. Similarly, there are conflicting reports of vertical transmission of FIV. The aim of the present study was to document the FIV serological status of cats taken into two rescue shelters. At rescue shelter 1 (Rescue 1), cats cohabited in a multi-cat household of FIV-negative and naturally-infected, FIV-positive cats. A study was performed that combined a retrospective review of records of FIV serological status at intake (Test 1) and prospective FIV serological testing (Tests 2 and 3). Retrospective records were analyzed at rescue shelter 2 (Rescue 2), where FIV-positive queens with litters of nursing kittens were taken into the shelter, before being rehomed. FIV serology was performed on all kittens after weaning. Initial test results (Test 1) for 138 cohabiting cats from Rescue 1 showed that there were 130 FIV-negative cats and eight FIV-positive cats (six male neutered and two female spayed). A second test (Test 2), performed in 45 of the FIV-negative and five of the FIV-positive cats at median 28 months after Test 1 (range, 1 month to 8.8 years) showed that results were unchanged. Similarly, a third test (Test 3), performed in four of the original FeLV-negative cats and one remaining FIV-positive cat at median 38 months after Test 1 (range, 4 months to 4 years), also showed that results were unchanged. These results show a lack of evidence of FIV transmission, despite years of exposure to naturally-infected, FIV-positive cats in a mixed household. At Rescue 2, records were available from five FIV-positive queens with 19 kittens. All 19 kittens tested FIV-negative, suggesting that vertical transmission had not occurred. Copyright © 2014 Elsevier Ltd. All rights reserved.
Bernard, C.; Keesee, B.; Philippoff, C.; Curran, S.; Lotz, J.; Powell, E.
Investigators, including three REU interns, conducted an experiment to quantify parameters for an epidemiological model designed to estimate disease transmission in marine invertebrates. White spot syndrome virus (WSSV) is a highly pathogenic disease affecting commercially important penaeid shrimp fisheries worldwide. The virus devastates penaeid shrimp but other varieties of decapods may serve as reservoirs for disease by being less susceptible to WSSV or refractory to disease. Non-penaeid crustaceans are less susceptible to WSSV, and different species have variable resistance to the disease leading to different potential to serve as reservoirs for transmission of the disease to coastal penaeid fisheries. This study investigates virulence and transmission rates of WSSV in two palaemonid shrimp which are keystone members of coastal food webs, and effects of species interactions on transmission rates of WSSV are estimated in a laboratory setting as a proxy for natural habitats. Two species of grass shrimp were exposed to a Chinese strain of WSSV through feeding the test individuals with previously prepared, inoculated penaeid shrimp. Replicated tanks containing 30 animals were exposed to the virus in arenas containing one or both species for 24 hours, then isolated in 1 liter tanks and monitored. During the isolation period moribund individuals were preserved for later analysis. After 7 days all test individuals were analyzed using qPCR to determine WSSV presence and load in DNA. From these data transmission rates, mortality, and viral concentration were quantified and used as parameters in a simple epidemiological model.
Wu, Elizabeth; Yang, Ming; Rao, Huiying; Fu, Sherry; Feng, Bo; Fei, Ran; Lin, Andy; Fontana, Robert J; Wei, Lai; Lok, Anna S
Predominant modes of hepatitis C virus (HCV) transmission vary between countries and over time. To compare HCV transmission modes in the USA and northern China. We conducted a prospective study enrolling two cohorts of chronic HCV patients in the USA, and in China at Beijing, and at Gu'an and Kuancheng counties in Hebei. Patients self-reported the most likely source and year of infection. A total of 1957 patients were studied (1000 USA; 957 China-428 Beijing, 387 Gu'an, 142 Kuancheng). The predominant infection sources were transfusion (23.0%) and injection drug use (IDU) (32.1%) in the USA and transfusion (64.5%) in northern China. Within China, transfusion was the most common source in Beijing (62.1%) and Gu'an (88.1%), and medical procedures (35.9%) and IDU (12.0%) in Kuancheng. Infection via transfusion decreased significantly in the USA (35.1-4.6%) and Beijing (84.2-14.3%) but remained frequent in Gu'an (90.5-72.5%) over time. Infection via IDU decreased from 32.4% in those ≥61 years to 25.0% in those 41-50 years but increased to 46.5% in those ≤40 years in US patients and decreased over time from 38.7 to 1.9% in Kuancheng. Infection via medical procedures increased over time in Beijing (7.0-33.3%) and remained frequent in Kuancheng (45.2-31.1%). There are major differences in presumed HCV infection source between the USA and northern China. Favorable as well as worrisome changes in the modes of HCV transmission in both countries were observed.
Full Text Available Zika virus transmission dynamics in urban environments follow a complex spatiotemporal pattern that appears unpredictable and barely related to high mosquito density areas. In this context, human activity patterns likely have a major role in Zika transmission dynamics. This paper examines the effect of host variability in the amount of time spent outdoors on Zika epidemiology in an urban environment.First, we performed a survey on time spent outdoors by residents of Miami-Dade County, Florida. Second, we analyzed both the survey and previously published national data on outdoors time in the U.S. to provide estimates of the distribution of the time spent outdoors. Third, we performed a computational modeling evaluation of Zika transmission dynamics, based on the time spent outdoors by each person. Our analysis reveals a strong heterogeneity of the host population in terms of time spent outdoors-data are well captured by skewed gamma distributions. Our model-based evaluation shows that in a heterogeneous population, Zika would cause a lower number of infections than in a more homogenous host population (up to 4-fold differences, but, at the same time, the epidemic would spread much faster. We estimated that in highly heterogeneous host populations the timing of the implementation of vector control measures is the major factor for limiting the number of Zika infections.Our findings highlight the need of considering host variability in exposure time for managing mosquito-borne infections and call for the revision of the triggers for vector control strategies, which should integrate mosquito density data and human outdoor activity patterns in specific areas.
Amy C Morrison
Full Text Available Comprehensive, longitudinal field studies that monitor both disease and vector populations for dengue viruses are urgently needed as a pre-requisite for developing locally adaptable prevention programs or to appropriately test and license new vaccines.We report the results from such a study spanning 5 years in the Amazonian city of Iquitos, Peru where DENV infection was monitored serologically among approximately 2,400 members of a neighborhood-based cohort and through school-based absenteeism surveillance for active febrile illness among a subset of this cohort. At baseline, 80% of the study population had DENV antibodies, seroprevalence increased with age, and significant geographic variation was observed, with neighborhood-specific age-adjusted rates ranging from 67.1 to 89.9%. During the first 15 months, when DENV-1 and DENV-2 were co-circulating, population-based incidence rates ranged from 2-3 infections/100 person-years (p-years. The introduction of DENV-3 during the last half of 2001 was characterized by 3 distinct periods: amplification over at least 5-6 months, replacement of previously circulating serotypes, and epidemic transmission when incidence peaked at 89 infections/100 p-years.Neighborhood-specific baseline seroprevalence rates were not predictive of geographic incidence patterns prior to the DENV-3 introduction, but were closely mirrored during the invasion of this serotype. Transmission varied geographically, with peak incidence occurring at different times among the 8 geographic zones in approximately 16 km(2 of the city. The lag from novel serotype introduction to epidemic transmission and knowledge of spatially explicit areas of elevated risk should be considered for more effective application of limited resources for dengue prevention.
Xiao, Yanyu; Beier, John C.; Cantrell, Robert Stephen; Cosner, Chris; DeAngelis, Donald L.; Ruan, Shigui
Rift Valley fever (RVF) is an important mosquito-borne viral zoonosis in Africa and the Middle East that causes human deaths and significant economic losses due to huge incidences of death and abortion among infected livestock. Outbreaks of RVF are sporadic and associated with both seasonal and socioeconomic effects. Here we propose an almost periodic three-patch model to investigate the transmission dynamics of RVF virus (RVFV) among ruminants with spatial movements. Our findings indicate that, in Northeastern Africa, human activities, including those associated with the Eid al Adha feast, along with a combination of climatic factors such as rainfall level and hydrological variations, contribute to the transmission and dispersal of the disease pathogen. Moreover, sporadic outbreaks may occur when the two events occur together: 1) abundant livestock are recruited into areas at risk from RVF due to the demand for the religious festival and 2) abundant numbers of mosquitoes emerge. These two factors have been shown to have impacts on the severity of RVF outbreaks. Our numerical results present the transmission dynamics of the disease pathogen over both short and long periods of time, particularly during the festival time. Further, we investigate the impact on patterns of disease outbreaks in each patch brought by festival- and seasonal-driven factors, such as the number of livestock imported daily, the animal transportation speed from patch to patch, and the death rate induced by ceremonial sacrifices. In addition, our simulations show that when the time for festival preparation starts earlier than usual, the risk of massive disease outbreaks rises, particularly in patch 3 (the place where the religious ceremony will be held).
Verbeek, Martin; Dullemans, Annette M; van der Vlugt, René A A
Lettuce necrotic leaf curl virus (LNLCV) was described as the first non-tomato-infecting member of the genus Torradovirus. Until today, the virus was found only in The Netherlands in two different areas in open field crops of lettuce. In 2015, LNLCV was accepted by the ICTV as a new member of the genus Torradovirus. The tomato-infecting (TI) torradoviruses Tomato torrado virus (ToTV), Tomato marchitez virus (ToMarV) and Tomato chocolàte virus (ToChV) are transmitted by at least three whitefly species in a semi-persistent and stylet-borne manner. As LNLCV was transmitted in open fields in The Netherlands, where whiteflies are present only in low incidence, transmission studies were set up to identify the natural vector of LNLCV. Whitefly species which survive Dutch open field conditions during summer, as well as lettuce colonizing aphid species, were tested for their ability to transmit LNLCV. Lengths of acquisition and inoculation periods were chosen in accordance with the conditions for TI torradoviruses. Transmission experiments involving whiteflies were never successful. Transmission with aphids was only successful in case of the lettuce-currant aphid, Nasonovia ribisnigri. Localization of LNLCV virions in N. ribisnigri with a nested RT-PCR indicated the stylets as possible retention sites. The willow-carrot aphid Cavariella aegopodii did not transmit LNLCV in our transmission experiment but the virus could be detected in the stylets of this aphid, leaving C. aegopodii as a possible vector for LNLCV. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.
Blomqvist, Gunilla A M; Martin, Krister; Morein, Bror
In searching for the cause of experimental variations in respiratory research data, serology revealed the prevalence of antibodies against parainfluenza virus type 3 (PIV 3) in guinea pigs. The aim of the present study was to explore the transmission rate, course, and kinetics of enzootic PIV 3 infection in guinea pig breeding units. In the first part of the study, blood samples to be analyzed for PIV 3 antibodies were collected from guinea pigs of a PIV 3-positive breeding colony at different times after birth. In the same breeding unit, 6 of 12 2-week-old guinea pigs were relocated and separately housed. The PIV 3 serum antibody titers of the two groups were compared at various times from birth to 13 weeks after birth. In the second part of the study, the spread of infectious virus and virus persistence were explored by housing seronegative sentinel animals together with 2- to 3-week-old guinea pigs from three different PIV 3-positive breeding units. The guinea pigs remaining in the breeding colony as well as those removed and housed separately showed declining serum antibody titers for about 1 month after birth, thereafter the titers were stable until about 8 weeks after birth. Five weeks later, the mean antibody titer of the guinea pigs remaining in the breeding colony had increased to a markedly higher level than that of the relocated, separately housed guinea pigs. Seroconversion was demonstrated in 7 of the 14 sentinels housed with the 2- to 3-week-old guinea pigs from PIV 3-positive breeding units. Sentinels housed together with PIV 3-positive guinea pigs 24 weeks after the start of the experiment did not seroconvert. We conclude that young guinea pigs born to PIV 3-positive mothers were protected by maternal immunity against infection with PIV 3 during their first 14 days of life. The guinea pig offspring became infected during the period from about 2 weeks until 8 weeks after birth, as demonstrated by seroconversion of sentinel animals and an increasing
Full Text Available Yellow dwarf viruses cause the most economically important virus diseases of cereal crops worldwide and are transmitted by aphid vectors. The identification of aphid genes and proteins mediating virus transmission is critical to develop agriculturally sustainable virus management practices and to understand viral strategies for circulative movement in all insect vectors. Two cyclophilin B proteins, S28 and S29, were identified previously in populations of Schizaphisgraminum that differed in their ability to transmit the RPV strain of Cereal yellow dwarf virus (CYDV-RPV. The presence of S29 was correlated with F2 genotypes that were efficient virus transmitters. The present study revealed the two proteins were isoforms, and a single amino acid change distinguished S28 and S29. The distribution of the two alleles was determined in 12 F2 genotypes segregating for CYDV-RPV transmission capacity and in 11 genetically independent, field-collected S. graminum biotypes. Transmission efficiency for CYDV-RPV was determined in all genotypes and biotypes. The S29 isoform was present in all genotypes or biotypes that efficiently transmit CYDV-RPV and more specifically in genotypes that efficiently transport virus across the hindgut. We confirmed a direct interaction between CYDV-RPV and both S28 and S29 using purified virus and bacterially expressed, his-tagged S28 and S29 proteins. Importantly, S29 failed to interact with a closely related virus that is transported across the aphid midgut. We tested for in vivo interactions using an aphid-virus co-immunoprecipitation strategy coupled with a bottom-up LC-MS/MS analysis using a Q Exactive mass spectrometer. This analysis enabled us to identify a third cyclophilin protein, cyclophilin A, interacting directly or in complex with purified CYDV-RPV. Taken together, these data provide evidence that both cyclophilin A and B interact with CYDV-RPV, and these interactions may be important but not sufficient to mediate
Full Text Available Experimental infection of Muscovy ducks with V4 strain of Newcastle disease virus was undertaken to determine the response of the ducks to the virus and the possibility of virus transmission to ducks and chickens in village like conditions. Twelve ducks were randomly and equally divided into three groups of control, inoculated and in-contact. Additionally, the chickens were placed into two groups of four animals each, namely in-contact and control. The inoculated and in-contact ducks and in-contact chickens were kept together. The eye drop route was used for inoculation and hemagglutination inhibition (HI antibodies were measured for assessment of antibody response and cloacal and pharyngeal swabs were used for detection of the virus. The primary antibody response of inoculated ducks was very high and rapid (geometric mean titers [Log base 2] of up to 5.75 ± 0.50. The in-contact ducks showed antibody response with the same pattern but lower titers than the inoculated ducks (geometric mean titers [Log base 2] of up to 3.25 ± 1.70. The in-contact chickens showed a slight increase of HI antibody (geometric mean titers [Log base 2] of up to 2.25 ± 1.25 while the control chickens did not show any increase. The antibody response indicated the transmission of the virus to contact ducks and chickens. A single isolation of virus confirmed the ability of ducks to excrete the virus. It was concluded that the V4 strain of Newcastle disease virus was highly antigenic for ducks, and ducks can transmit it to other ducks and also in-contact chickens.
Full Text Available Background: On February 1st 2016 the WHO declared the Zika Virus (ZIKV infection a worldwide public health emergency because of its rapid expansion and severe complications, such as Guillain-Barré Syndrome or microcephaly in newborn. The huge amount of people traveling to endemic areas and the presence of Aedes albopictus in Barcelona increase the risk of autochtonous transmission. The objective of this study was to describe the first ZIKV cases diagnosed in our city and to analyze the surveillance, prevention, and control measures implemented to avoid autochthonous transmission.Methods: An observational cross-sectional population-based study in Barcelona, Spain was performed.An analysis of the socio-demographic, epidemiological, clinical characteristics, and mosquito control activities of the ZIKV cases detected between January 1st and December 2016 was carried out using a specific ZIKV epidemiological survey of the Barcelona Public Health Agency.Results: A total of 118 notifications of possible ZIKV infections were received, and 44 corresponded to confirmed cases in Barcelona residents.Amongst these, the median age was 35 years and 57% were women. All cases were imported, 48% were Spanish-born and 52% foreign-born. Dominican Republic was the most visited country amongst foreign-born patients and Nicaragua amongst Spanish-born. The most frequent symptoms were exanthema, fever, and arthralgia. Among the 24 diagnosed women, 6 (25% were pregnant. There was one case of microcephaly outside Barcelona city. Entomological inspections were done at the homes of 19 cases (43.2% of the total and in 34 (77.3% public spaces. Vector activity was found in one case of the 44 confirmed cases, and 134 surveillance and vector control were carried out associated to imported ZIKV cases. In all cases prevention measures were recommended to avoid mosquito bites on infected cases.Conclusion: Epidemiological and entomological surveillance are essential for the
Full Text Available Background: Epidemiology and transmission patterns of hepatitis C virus (HCV are important subjects as we enter a new era of treatment with directly acting antivirals (DAAs. The highest prevalence of HCV in developed countries is found among intravenous drug users (IDUs, where unsafe needle sharing practices provide the main route of infection. Efforts to prohibit the continuous spread of HCV among these groups have been initiated by the community services and health care providers. Our goal was to understand how HCV was transmitted among IDUs within a limited population group. We provide a retrospective study (2005–2007 of the HCV transmission patterns in a population of IDUs in the Uppsala region of Sweden. Method: Eighty-two serum samples were collected from IDUs in Uppsala County. Our reverse transcription nested polymerase chain reaction (RT-nested PCR and sequencing method enabled a comprehensive genetic analysis for a broad spectrum of genotypes of two relatively conserved regions, NS5B and NS3, that encodes for the viral polymerase and protease, respectively. HCV RNA in serum samples was amplified and sequenced with in-house primers. Sequence similarities between individuals and subgroups were analyzed with maximum likelihood (ML phylogenetic trees. Published HCV reference sequences from other geographic regions and countries were also included for clarity. Results: Phylogenetic analysis was possible for 59 NS5B (72% and 29 NS3 (35% sequences from Uppsala patients. Additionally, we also included 15 NS3 sequences from Örebro patients, making a total of 44 NS3 sequences for the analysis. By analyzing the NS3 sequences, two transmission sets were found between the IDUs (>98% sequence identity, with one set consisting of two individuals and another set consisting of three individuals. In addition, the phylogenetic analysis done with our serum samples displayed clusters that distinguished them from the reference sequences. Conclusion: Our
Full Text Available H7N9 viruses pose a threat to human health and they are no less harmful to the poultry industry than the H5N1 avian influenza viruses. However, the pathogenesis, transmissibility, and the host immune response of the H7N9 virus in chickens and mice remain unclear. In this study, we found that H7N9 viruses replicated in multiple organs of the chicken and viral shedding persisted up to 30 days postinoculation (DPI. The viruses were efficiently transmitted between chickens through direct contact. Notably, chickens infected with H7N9 had high antibody levels throughout the entire observation period and their antibody response lasted for 30 DPI. The expression levels of the pattern-recognition receptors and pro-inflammatory cytokines were found to be significantly upregulated in the brain using quantitative real-time PCR. The expression of TLR3, TLR7, MDA5, Mx, IL-1β, IL-6, IFN-α, and IFN-γ were also significantly different in the lungs of infected chickens. We found that the viruses isolated from these birds had low pathogenicity in mice, produced little weight loss and could only replicate in the lungs. Our findings suggested that the H7N9 viruses could replicate in chickens and mice and be efficiently transmitted between chickens, which presented a significant threat to human and poultry health.
Lewnard, Joseph A.; Ndeffo Mbah, Martial L.; Alfaro-Murillo, Jorge A.; Altice, Frederick L.; Bawo, Luke; Nyenswah, Tolbert G.; Galvani, Alison P.
Background A substantial scale-up in public health response is needed to control the unprecedented Ebola virus disease (EVD) epidemic in West Africa. Current international commitments seek to expand intervention capacity in three areas: new EVD Treatment Centers (ETCs); case ascertainment through contact tracing; and household protective kit allocation. Methods We developed a transmission model of Ebola virus that we fitted to reported EVD cases and deaths in Montserrado County, Liberia. We used this model to evaluate effectiveness of expanding ETCs, improving case ascertainment, and allocating protective kits for controlling the outbreak in Montserrado. Findings We estimated the basic reproductive number for EVD in Montserrado to be 2·49 [2·38–2·60]. We expect that allocating 4,800 additional ETC beds and increasing case ascertainment fivefold in November can avert 77312 [68400–85870] cases relative to the status quo by 15 December. Complementing these measures with protective kit allocation increases the expectation as high as 97940 [90096–105606] cases. If deployed by 15 October, equivalent interventions would have been expected to avert 137432 [129736–145874] cases. If delayed to 15 November, we expect the interventions will at best avert 53957 [49963–60490] cases. Interpretation The number of ETC beds needed to effectively control EVD in Montserrado substantially exceeds the total pledged by the United States to West Africa. Accelerated case ascertainment is required to maximize effectiveness of expanding ETC capacity. Distributing protective kits can further augment EVD prevention. Our findings highlight the rapidly closing window of opportunity for controlling the outbreak and averting a catastrophic toll of EVD cases and deaths. Funding NIH: U01-GM087719, U01-GM105627, K24-DA017072 PMID:25455986
Estelle H. Venter
Full Text Available Bluetongue (BT, a disease that affects mainly sheep, causes economic losses owing to not only its deleterious effects on animals but also its associated impact on the restriction of movement of livestock and livestock germplasm. The causative agent, bluetongue virus (BTV, can occur in the semen of rams and bulls at the time of peak viraemia and be transferred to a developing foetus. The risk of the transmission of BTV by bovine embryos is negligible if the embryos are washed according to the International Embryo Transfer Society (IETS protocol. Two experiments were undertaken to determine whether this holds for ovine embryos that had been exposed to BTV. Firstly, the oestrus cycles of 12 ewes were synchronised and the 59 embryos that were obtained were exposed in vitro to BTV-2 and BTV-4 at a dilution of 1 x 102.88 and 1 x 103.5 respectively. In the second experiment, embryos were recovered from sheep at the peak of viraemia. A total of 96 embryos were collected from BTV-infected sheep 21 days after infection. In both experiments half the embryos were washed and treated with trypsin according to the IETS protocol while the remaining embryos were neither washed nor treated. All were tested for the presence of BTV using cell culture techniques. The virus was detected after three passages in BHK-21 cells only in one wash bath in the first experiment and two unwashed embryos exposed to BTV-4 at a titre of 1 x 103.5. No embryos or uterine flush fluids obtained from viraemic donors used in the second experiment were positive for BTV after the standard washing procedure had been followed. The washing procedure of the IETS protocol can thus clear sheep embryos infected with BTV either in vitro or in vivo.
Steininger, Christoph; Kundi, Michael; Jatzko, Gerlinde; Kiss, Herbert; Lischka, Andreas; Holzmann, Heidemarie
Virological and clinical data from 73 hepatitis C virus (HCV)-infected pregnant women who gave birth to 75 children were merged retrospectively, by logistic regression analysis, to investigate risk factors for vertical transmission of HCV. Eighty-two percent of the HCV-infected mothers were HCV-RNA-positive during pregnancy, and 10% were coinfected with human immunodeficiency virus (HIV). Nine children were HCV infected, 1 was HIV infected, but none was HIV-HCV coinfected. Among vaginal deliveries, the mean HCV load of mothers who transmitted HCV to their infants was higher than that of those who did not (8.1 x 10(5) vs. 1.4 x 10(4) copies/mL; P=.056). A reduction in umbilical cord-blood pH (relative risk, 3.9; P=.04) or the occurrence of perineal or vaginal laceration (relative risk, 6.4; P=.028) during vaginal delivery significantly increased the risk of vertical HCV transmission. In conclusion, high maternal viremia, infantile hypoxia, and intrapartum exposure to virus-contaminated maternal blood increased the risk of HCV transmission during vaginal deliveries. Consequently, cesarean section may reduce the risk of vertical HCV transmission in selected cases.
Bovine viral diarrhoea virus (BVDV) is an economically important pathogen of cattle worldwide. Infection of a pregnant animal may lead to persistent infection of the foetus and birth of a persistently infected (PI) calf that sheds the virus throughout its life. However, BVD viruses are not strictly species specific. BVDV has been isolated from many domesticated and wild ruminants. This is of practical importance as virus reservoirs in non-bovine hosts may hamper BVDV control in cattle. A goat given as a social companion to a BVDV PI calf gave birth to a PI goat kid. In order to test if goat to goat infections were possible, seronegative pregnant goats were exposed to the PI goat. In parallel, seronegative pregnant goats were kept together with the PI calf. Only the goat to goat transmission resulted in the birth of a next generation of BVDV PI kids whereas all goats kept together with the PI calf aborted. To our knowledge, this is the first report which shows that a PI goat cannot only transmit BVD virus to other goats but that such transmission may indeed lead to the birth of a second generation of PI goats. Genetic analyses indicated that establishment in the new host species may be associated with step-wise adaptations in the viral genome. Thus, goats have the potential to be a reservoir for BVDV. However, the PI goats showed growth retardation and anaemia and their survival under natural conditions remains questionable. PMID:23675947
Bachofen, Claudia; Vogt, Hans-Rudolf; Stalder, Hanspeter; Mathys, Tanja; Zanoni, Reto; Hilbe, Monika; Schweizer, Matthias; Peterhans, Ernst
Bovine viral diarrhoea virus (BVDV) is an economically important pathogen of cattle worldwide. Infection of a pregnant animal may lead to persistent infection of the foetus and birth of a persistently infected (PI) calf that sheds the virus throughout its life. However, BVD viruses are not strictly species specific. BVDV has been isolated from many domesticated and wild ruminants. This is of practical importance as virus reservoirs in non-bovine hosts may hamper BVDV control in cattle. A goat given as a social companion to a BVDV PI calf gave birth to a PI goat kid. In order to test if goat to goat infections were possible, seronegative pregnant goats were exposed to the PI goat. In parallel, seronegative pregnant goats were kept together with the PI calf. Only the goat to goat transmission resulted in the birth of a next generation of BVDV PI kids whereas all goats kept together with the PI calf aborted. To our knowledge, this is the first report which shows that a PI goat cannot only transmit BVD virus to other goats but that such transmission may indeed lead to the birth of a second generation of PI goats. Genetic analyses indicated that establishment in the new host species may be associated with step-wise adaptations in the viral genome. Thus, goats have the potential to be a reservoir for BVDV. However, the PI goats showed growth retardation and anaemia and their survival under natural conditions remains questionable.
da Silva, Suely Gonçalves Cordeiro; Leon, Luciane Almeida Amado; Alves, Gilda; Brito, Selma Magalhães; Sandes, Valcieny de Souza; Lima, Magda Maria Adorno Ferreira; Nogueira, Marta Colares; Tavares, Rita de Cássia Barbosa da Silva; Dobbin, Jane; Apa, Alexandre; de Paula, Vanessa Salete; Oliveira, Jaqueline Mendes de Oliveira; Pinto, Marcelo Alves; Ferreira, Orlando da Costa; Motta, Iara de Jesus Ferreira
This paper describes the transmission of hepatitis A virus (HAV) to two blood recipients from a healthy donor that later presented to the blood bank with jaundice. The RNA of HAV was detected by qualitative nested reverse transcription polymerase chain reaction (nested RT-PCR) and quantified by real-time RT-PCR. HAV RNA samples were genotyped by direct sequencing of PCR products. A sequence from a fragment of 168 bp from the VP1/2A HAV region was used to construct a phylogenetic tree. A 31-year-old male donor accepted for donation of a whole blood unit returned to the blood bank with clinical jaundice 20 days after donation. His serological and NAT tests were negative for HBV and HCV. Serological tests for HAV IgM and IgG were negative on donation sample but positive on follow-up sample, confirming donor's HAV acute infection. Both recipients of red blood cells (R1) and platelet concentrate (R2) from the same implicated donation were HAV IgM-negative and IgG-positive. Qualitative PCR was positive on samples from all three individuals and phylogenetic analysis of viruses proved HAV transmission to the two recipients of blood products. HAV viral load on donor follow-up sample and the platelet recipient was 1.3 and 1.5 × 10(3) IU/ml, respectively. The RBC recipient, also infected by HCV, was undergoing bone marrow transplantation and died from fulminant hepatitis, 26 days after the implicated HAV transfusion. The blood donor, a garbage collector, spontaneously returned to the blood bank when developing jaundice. This highlights the importance of donor education to immediately report to blood banks of any signs and symptoms related to infectious disease developed after blood donation. The fact that one immunocompromised patient with HCV infection died from fulminant hepatitis after receiving a HAV-contaminated platelet transfusion underpins the importance of a HAV vaccination program for these group of patients.
Full Text Available H5N1 highly pathogenic avian influenza virus (HPAIV of clade 2.3.2 has been circulating in waterfowl in Southern China since 2003. Our previous studies showed that certain H5N1 HPAIV isolates within clade 2.3.2 from Southern China had high pathogenicity in different birds. Guinea pigs have been successfully used as models to evaluate the transmissibility of AIVs and other species of influenza viruses in mammalian hosts. However, few studies have reported pathogenicity and transmissibility of H5N1 HPAIVs of this clade in guinea pigs. In this study, we selected an H5N1 HPAIV isolate, A/duck/Guangdong/357/2008, to investigate the pathogenicity and transmissibility of the virus in guinea pigs. The virus had high pathogenicity in mice; additionally, it only replicated in some tissues of the guinea pigs without production of clinical signs, but was transmissible among guinea pigs. Interestingly, virus isolates from co-caged guinea pigs had the D701N mutation in the PB2 protein. These mutant viruses showed higher pathogenicity in mice and higher replication capability in guinea pigs but did not demonstrate enhanced the transmissibility among guinea pigs. These findings indicate the transmission of the H5N1 virus between mammals could induce virus mutations, and the mutant viruses might have higher pathogenicity in mammals without higher transmissibility. Therefore, the continued evaluation of the pathogenicity and transmissibility of avian influenza virus (AIVs in mammals is critical to the understanding of the evolutionary characteristics of AIVs and the emergence of potential pandemic strains.
Kuhn, Susan; Twele-Montecinos, Loreto; MacDonald, Judy; Webster, Patricia; Law, Barbara
The 17D yellow fever vaccine is a live-virus vaccine that has been in use since the 1940s. The incidence of encephalitis after yellow fever vaccination among young infants is much higher than among children older than nine months of age. Until recently, avoidance of vaccination by breastfeeding women who have received yellow fever vaccine had been based on theoretical grounds only. We report the probable transmission of vaccine strain of yellow fever virus from a mother to her infant through ...
Brault, V.; Bergdoll, M.; Mutterer, J.; Prasad, V.; Pfeffer, S.; Erdinger, M.; Richards, K. E.; Ziegler-Graff, V.
Point mutations were introduced into the major capsid protein (P3) of cloned infectious cDNA of the polerovirus beet western yellows virus (BWYV) by manipulation of cloned infectious cDNA. Seven mutations targeted sites on the S domain predicted to lie on the capsid surface. An eighth mutation eliminated two arginine residues in the R domain, which is thought to extend into the capsid interior. The effects of the mutations on virus capsid formation, virus accumulation in protoplasts and plants, and aphid transmission were tested. All of the mutants replicated in protoplasts. The S-domain mutant W166R failed to protect viral RNA from RNase attack, suggesting that this particular mutation interfered with stable capsid formation. The R-domain mutant R7A/R8A protected ∼90% of the viral RNA strand from RNase, suggesting that lower positive-charge density in the mutant capsid interior interfered with stable packaging of the complete strand into virions. Neither of these mutants systemically infected plants. The six remaining mutants properly packaged viral RNA and could invade Nicotiana clevelandii systemically following agroinfection. Mutant Q121E/N122D was poorly transmitted by aphids, implicating one or both targeted residues in virus-vector interactions. Successful transmission of mutant D172N was accompanied either by reversion to the wild type or by appearance of a second-site mutation, N137D. This finding indicates that D172 is also important for transmission but that the D172N transmission defect can be compensated for by a “reverse” substitution at another site. The results have been used to evaluate possible structural models for the BWYV capsid. PMID:12584348
Paul J Wichgers Schreur
Full Text Available Rift Valley fever virus (RVFV is transmitted among susceptible animals by mosquito vectors. Although the virus can be isolated from nasal and oral swabs of infected animals and is known to be highly infectious when administered experimentally via oral or respiratory route, horizontal transmission of the virus is only sporadically reported in literature. We considered that immunosuppression resulting from stressful conditions in the field may increase the susceptibility to horizontally transmitted RVFV. Additionally, we reasoned that horizontal transmission may induce immune responses that could affect the susceptibility of contact-exposed animals to subsequent infection via mosquito vectors. To address these two hypotheses, viremic lambs were brought into contact with sentinel lambs. One group of sentinel lambs was treated with the immunosuppressive synthetic glucocorticosteroid dexamethasone and monitored for signs of disease and presence of virus in the blood and target organs. Another group of contact-exposed sentinel lambs remained untreated for three weeks and was subsequently challenged with RVFV. We found that none of the dexamethasone-treated contact-exposed lambs developed detectable viremia, antibody responses or significant increases in cytokine mRNA levels. Susceptibility of immunocompetent lambs to RVFV infection was not influenced by previous contact-exposure. Our results are discussed in light of previous findings.
Howe, Kevin; Fish, Tara; Smith, Dawn; Gildow, Fredrick; MacCoss, Michael J.; Thannhauser, Theodore W.; Gray, Stewart M.
Circulative transmission of viruses in the Luteoviridae, such as cereal yellow dwarf virus (CYDV), requires a series of precisely orchestrated interactions between virus, plant, and aphid proteins. Natural selection has favored these viruses to be retained in the phloem to facilitate acquisition and transmission by aphids. We show that treatment of infected oat tissue homogenate with sodium sulfite reduces transmission of the purified virus by aphids. Transmission electron microscopy data indicated no gross change in virion morphology due to treatments. However, treated virions were not acquired by aphids through the hindgut epithelial cells and were not transmitted when injected directly into the hemocoel. Analysis of virus preparations using nanoflow liquid chromatography coupled to tandem mass spectrometry revealed a number of host plant proteins co-purifying with viruses, some of which were lost following sodium sulfite treatment. Using targeted mass spectrometry, we show data suggesting that several of the virus-associated host plant proteins accumulated to higher levels in aphids that were fed on CYDV-infected plants compared to healthy plants. We propose two hypotheses to explain these observations, and these are not mutually exclusive: (a) that sodium sulfite treatment disrupts critical virion-host protein interactions required for aphid transmission, or (b) that host infection with CYDV modulates phloem protein expression in a way that is favorable for virus uptake by aphids. Importantly, the genes coding for the plant proteins associated with virus may be examined as targets in breeding cereal crops for new modes of virus resistance that disrupt phloem-virus or aphid-virus interactions. PMID:23118947
Full Text Available Circulative transmission of viruses in the Luteoviridae, such as cereal yellow dwarf virus (CYDV, requires a series of precisely orchestrated interactions between virus, plant, and aphid proteins. Natural selection has favored these viruses to be retained in the phloem to facilitate acquisition and transmission by aphids. We show that treatment of infected oat tissue homogenate with sodium sulfite reduces transmission of the purified virus by aphids. Transmission electron microscopy data indicated no gross change in virion morphology due to treatments. However, treated virions were not acquired by aphids through the hindgut epithelial cells and were not transmitted when injected directly into the hemocoel. Analysis of virus preparations using nanoflow liquid chromatography coupled to tandem mass spectrometry revealed a number of host plant proteins co-purifying with viruses, some of which were lost following sodium sulfite treatment. Using targeted mass spectrometry, we show data suggesting that several of the virus-associated host plant proteins accumulated to higher levels in aphids that were fed on CYDV-infected plants compared to healthy plants. We propose two hypotheses to explain these observations, and these are not mutually exclusive: (a that sodium sulfite treatment disrupts critical virion-host protein interactions required for aphid transmission, or (b that host infection with CYDV modulates phloem protein expression in a way that is favorable for virus uptake by aphids. Importantly, the genes coding for the plant proteins associated with virus may be examined as targets in breeding cereal crops for new modes of virus resistance that disrupt phloem-virus or aphid-virus interactions.
Cilia, Michelle; Peter, Kari A; Bereman, Michael S; Howe, Kevin; Fish, Tara; Smith, Dawn; Gildow, Fredrick; MacCoss, Michael J; Thannhauser, Theodore W; Gray, Stewart M
Circulative transmission of viruses in the Luteoviridae, such as cereal yellow dwarf virus (CYDV), requires a series of precisely orchestrated interactions between virus, plant, and aphid proteins. Natural selection has favored these viruses to be retained in the phloem to facilitate acquisition and transmission by aphids. We show that treatment of infected oat tissue homogenate with sodium sulfite reduces transmission of the purified virus by aphids. Transmission electron microscopy data indicated no gross change in virion morphology due to treatments. However, treated virions were not acquired by aphids through the hindgut epithelial cells and were not transmitted when injected directly into the hemocoel. Analysis of virus preparations using nanoflow liquid chromatography coupled to tandem mass spectrometry revealed a number of host plant proteins co-purifying with viruses, some of which were lost following sodium sulfite treatment. Using targeted mass spectrometry, we show data suggesting that several of the virus-associated host plant proteins accumulated to higher levels in aphids that were fed on CYDV-infected plants compared to healthy plants. We propose two hypotheses to explain these observations, and these are not mutually exclusive: (a) that sodium sulfite treatment disrupts critical virion-host protein interactions required for aphid transmission, or (b) that host infection with CYDV modulates phloem protein expression in a way that is favorable for virus uptake by aphids. Importantly, the genes coding for the plant proteins associated with virus may be examined as targets in breeding cereal crops for new modes of virus resistance that disrupt phloem-virus or aphid-virus interactions.
Takemoto, Masaya; Imasawa, Takayoshi; Yamanishi, Koichi; Mori, Yasuko
Human herpesvirus 6 (HHV-6) is a ubiquitous betaherpesvirus that predominantly infects and replicates in CD4 + T lymphocytes. However, the mechanism of HHV-6 transmission to T cells from the peripheral mucosa is unknown. Here we found that dendritic cells (DCs) can transmit HHV-6 to T cells, resulting in productive infection. In immature monocyte-derived DCs (MDDCs) infected with HHV-6, viral early and late antigens were expressed, and nucleocapsids containing a DNA core were observed, although few virions were detected in the cytoplasm by electron microscopy, indicating that the maturation of HHV-6 virions may be incomplete in MDDCs. However, HHV-6 transmission from MDDCs to stimulated CD4 + T cells occurred efficiently in coculture of these cells, but not from MDDCs culture supernatants. This transmission was partially inhibited by treating the DCs with a viral DNA synthesis blocker, indicating that viral replication in MDDCs is required for this transmission. Furthermore, myeloid DCs and plasmacytoid DCs infected with HHV-6 could also transmit the virus to stimulated T cells. Thus, DCs may be the first cell population targeted by HHV-6 and could play an important role in the virus' transmission to T cells for their further propagation
Yang, Yinli; Han, Qiuju; Hou, Zhaohua; Zhang, Cai; Tian, Zhigang; Zhang, Jian
Evidence suggests that exosomes can transfer genetic material between cells. However, their roles in hepatitis B virus (HBV) infection remain unclear. Here, we report that exosomes present in the sera of chronic hepatitis B (CHB) patients contained both HBV nucleic acids and HBV proteins, and transferred HBV to hepatocytes in an active manner. Notably, HBV nucleic acids were detected in natural killer (NK) cells from both CHB patients and healthy donors after exposure to HBV-positive exosomes. Through real-time fluorescence microscopy and flow cytometry, 1,1'-dioctadecyl-3,3,3',3',-tetramethylindodicarbocyanine, 4-chlorobenzenesulfnate salt (DiD)-labeled exosomes were observed to interact with NK cells and to be taken up by NK cells, which was enhanced by transforming growth factor-β treatment. Furthermore, HBV-positive exosomes impaired NK-cell functions, including interferon (IFN)-γ production, cytolytic activity, NK-cell proliferation and survival, as well as the responsiveness of the cells to poly (I:C) stimulation. HBV infection suppressed the expression of pattern-recognition receptors, especially retinoic acid inducible gene I (RIG-I), on NK cells, resulting in the dampening of the nuclear factor κB(NF-κB) and p38 mitogen-activated protein kinase pathways. Our results highlight a previously unappreciated role of exosomes in HBV transmission and NK-cell dysfunction during CHB infection. PMID:27238466
Tohme, Rania A.; Holmberg, Scott D.
Tattoos and piercings are increasing, especially among youths, but the risk of hepatitis C virus (HCV) infection from these practices has not been adequately assessed and there are conflicting findings in the literature. We evaluated the risk of HCV infection from tattooing and piercing using the Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines. Studies that specified the venue of tattooing and/or piercing showed no definitive evidence for an increased risk of HCV infection when tattoos and piercings were received in professional parlors. However, the risk of HCV infection is significant, especially among high-risk groups (adjusted odds ratio, 2.0–3.6), when tattoos are applied in prison settings or by friends. Prevention interventions are needed to avoid the transmission of hepatitis C from tattooing and piercing in prisons, homes, and other potentially nonsterile settings. Youths also should be educated on the need to have tattoos and piercings performed under sterile conditions to avoid HCV infection. PMID:22291098
Ding, Li [College of Veterinary Medicine, Northwest A and F University, Yangling, Shaanxi 712100 (China); College of Life Sciences, Hainan Normal University, Haikou, Hainan 571158 (China); Zhao, Xiaomin; Huang, Yong; Du, Qian; Dong, Feng; Zhang, Hongling; Song, Xiangjun; Zhang, Wenlong [College of Veterinary Medicine, Northwest A and F University, Yangling, Shaanxi 712100 (China); Tong, Dewen, E-mail: email@example.com [College of Veterinary Medicine, Northwest A and F University, Yangling, Shaanxi 712100 (China)
Highlights: •TGEV infection induced ROS accumulation. •ROS accumulation is involved in TGEV-induced mitochondrial integrity impairment. •ROS is associated with p53 activation and apoptosis occurrence in TGEV-infected cells. -- Abstract: Transmissible gastroenteritis virus (TGEV), an enteropathogenic coronavirus, causes severe lethal watery diarrhea and dehydration in piglets. Previous studies indicate that TGEV infection induces cell apoptosis in host cells. In this study, we investigated the roles and regulation of reactive oxygen species (ROS) in TGEV-activated apoptotic signaling. The results showed that TGEV infection induced ROS accumulation, whereas UV-irradiated TGEV did not promote ROS accumulation. In addition, TGEV infection lowered mitochondrial transmembrane potential in PK-15 cell line, which could be inhibited by ROS scavengers, pyrrolidinedithiocarbamic (PDTC) and N-acetyl-L-cysteine (NAC). Furthermore, the two scavengers significantly inhibited the activation of p38 MAPK and p53 and further blocked apoptosis occurrence through suppressing the TGEV-induced Bcl-2 reduction, Bax redistribution, cytochrome c release and caspase-3 activation. These results suggest that oxidative stress pathway might be a key element in TGEV-induced apoptosis and TGEV pathogenesis.
A review of patient notification exercises (PNEs) carried out in Ireland between 1997 and 2011 to investigate potential exposure to blood-borne viruses (BBVs) in healthcare settings was undertaken to inform future policy and practice. A questionnaire was sent to key informants in the health services to identify all relevant PNEs. Structured interviews were conducted with key investigators, and available documentation was examined. Ten BBV-related PNEs were identified. Despite testing over 2000 patients, only one case of transmission was found. However, in-depth local investigations before undertaking the PNEs identified six cases of healthcare-associated transmission.
Crabtree, Mary B; Kent Crockett, Rebekah J; Bird, Brian H; Nichol, Stuart T; Erickson, Bobbie Rae; Biggerstaff, Brad J; Horiuchi, Kalanthe; Miller, Barry R
Rift Valley fever virus is an arthropod-borne human and animal pathogen responsible for large outbreaks of acute and febrile illness throughout Africa and the Arabian Peninsula. Reverse genetics technology has been used to develop deletion mutants of the virus that lack the NSs and/or NSm virulence genes and have been shown to be stable, immunogenic and protective against Rift Valley fever virus infection in animals. We assessed the potential for these deletion mutant viruses to infect and be transmitted by Aedes mosquitoes, which are the principal vectors for maintenance of the virus in nature and emergence of virus initiating disease outbreaks, and by Culex mosquitoes which are important amplification vectors. Aedes aegypti and Culex quinquefasciatus mosquitoes were fed bloodmeals containing the deletion mutant viruses. Two weeks post-exposure mosquitoes were assayed for infection, dissemination, and transmission. In Ae. aegypti, infection and transmission rates of the NSs deletion virus were similar to wild type virus while dissemination rates were significantly reduced. Infection and dissemination rates for the NSm deletion virus were lower compared to wild type. Virus lacking both NSs and NSm failed to infect Ae. aegypti. In Cx. quinquefasciatus, infection rates for viruses lacking NSm or both NSs and NSm were lower than for wild type virus. In both species, deletion of NSm or both NSs and NSm reduced the infection and transmission potential of the virus. Deletion of both NSs and NSm resulted in the highest level of attenuation of virus replication. Deletion of NSm alone was sufficient to nearly abolish infection in Aedes aegypti mosquitoes, indicating an important role for this protein. The double deleted viruses represent an ideal vaccine profile in terms of environmental containment due to lack of ability to efficiently infect and be transmitted by mosquitoes.
Mary B Crabtree
Full Text Available BACKGROUND: Rift Valley fever virus is an arthropod-borne human and animal pathogen responsible for large outbreaks of acute and febrile illness throughout Africa and the Arabian Peninsula. Reverse genetics technology has been used to develop deletion mutants of the virus that lack the NSs and/or NSm virulence genes and have been shown to be stable, immunogenic and protective against Rift Valley fever virus infection in animals. We assessed the potential for these deletion mutant viruses to infect and be transmitted by Aedes mosquitoes, which are the principal vectors for maintenance of the virus in nature and emergence of virus initiating disease outbreaks, and by Culex mosquitoes which are important amplification vectors. METHODOLOGY AND PRINCIPAL FINDINGS: Aedes aegypti and Culex quinquefasciatus mosquitoes were fed bloodmeals containing the deletion mutant viruses. Two weeks post-exposure mosquitoes were assayed for infection, dissemination, and transmission. In Ae. aegypti, infection and transmission rates of the NSs deletion virus were similar to wild type virus while dissemination rates were significantly reduced. Infection and dissemination rates for the NSm deletion virus were lower compared to wild type. Virus lacking both NSs and NSm failed to infect Ae. aegypti. In Cx. quinquefasciatus, infection rates for viruses lacking NSm or both NSs and NSm were lower than for wild type virus. CONCLUSIONS/SIGNIFICANCE: In both species, deletion of NSm or both NSs and NSm reduced the infection and transmission potential of the virus. Deletion of both NSs and NSm resulted in the highest level of attenuation of virus replication. Deletion of NSm alone was sufficient to nearly abolish infection in Aedes aegypti mosquitoes, indicating an important role for this protein. The double deleted viruses represent an ideal vaccine profile in terms of environmental containment due to lack of ability to efficiently infect and be transmitted by mosquitoes.
Full Text Available One of the potential threats to public health microbiology in 21st century is the increased mortality rate caused by Zika virus (ZIKV, a mosquito-borne flavivirus. The severity of ZIKV infection urged World Health Organization (WHO to declare this virus as a global concern. The limited knowledge on the structure, virulent factors, and replication mechanism of the virus posed as hindrance for vaccine development. Several vector and non-vector-borne mode of transmission are observed for spreading the disease. The similarities of the virus with other flaviviruses such as dengue and West Nile virus are worrisome; hence, there is high scope to undertake ZIKV research that probably provide insight for novel therapeutic intervention. Thus, this review focuses on the recent aspect of ZIKV research which includes the outbreak, genome structure, multiplication and propagation of the virus, current animal models, clinical manifestations, available treatment options (probable vaccines and therapeutics, and the recent advancements in computational drug discovery pipelines, challenges and limitation to undertake ZIKV research. The review suggests that the infection due to ZIKV became one of the universal concerns and an interdisciplinary environment of in vitro cellular assays, genomics, proteomics, and computational biology approaches probably contribute insights for screening of novel molecular targets for drug design. The review tried to provide cutting edge knowledge in ZIKV research with future insights required for the development of novel therapeutic remedies to curtail ZIKV infection.
Domier, Leslie L; Hobbs, Houston A; McCoppin, Nancy K; Bowen, Charles R; Steinlage, Todd A; Chang, Sungyul; Wang, Yi; Hartman, Glen L
Infection of soybean plants with Soybean mosaic virus (SMV), which is transmitted by aphids and through seed, can cause significant reductions in seed production and quality. Because seedborne infections are the primary sources of inoculum for SMV infections in North America, host-plant resistance to seed transmission can limit the pool of plants that can serve as sources of inoculum. To examine the inheritance of SMV seed transmission in soybean, crosses were made between plant introductions (PIs) with high (PI88799), moderate (PI60279), and low (PI548391) rates of transmission of SMV through seed. In four F(2) populations, SMV seed transmission segregated as if conditioned by two or more genes. Consequently, a recombinant inbred line population was derived from a cross between PIs 88799 and 548391 and evaluated for segregation of SMV seed transmission, seed coat mottling, and simple sequence repeat markers. Chromosomal regions on linkage groups C1 and C2 were significantly associated with both transmission of isolate SMV 413 through seed and SMV-induced seed coat mottling, and explained ≈42.8 and 46.4% of the variability in these two traits, respectively. Chromosomal regions associated with seed transmission and seed coat mottling contained homologues of Arabidopsis genes DCL3 and RDR6, which encode enzymes involved in RNA-mediated transcriptional and posttranscriptional gene silencing.
Reddy, Kondreddy Eswar; Thu, Ha Thi; Yoo, Mi Sun; Ramya, Mummadireddy; Reddy, Bheemireddy Anjana; Lien, Nguyen Thi Kim; Trang, Nguyen Thi Phuong; Duong, Bui Thi Thuy; Lee, Hyun-Jeong; Kang, Seung-Won; Quyen, Dong Van
Sacbrood virus (SBV) is one of the most common viral infections of honeybees. The entire genome sequence for nine SBV infecting honeybees, Apis cerana and Apis mellifera, in Vietnam, namely AcSBV-Viet1, AcSBV-Viet2, AcSBV-Viet3, AmSBV-Viet4, AcSBV-Viet5, AmSBV-Viet6, AcSBV-Viet7, AcSBV-Viet8, and AcSBV-Viet9, was determined. These sequences were aligned with seven previously reported complete genome sequences of SBV from other countries, and various genomic regions were compared. The Vietnamese SBVs (VN-SBVs) shared 91-99% identity with each other, and shared 89-94% identity with strains from other countries. The open reading frames (ORFs) of the VN-SBV genomes differed greatly from those of SBVs from other countries, especially in their VP1 sequences. The AmSBV-Viet6 and AcSBV-Viet9 genome encodes 17 more amino acids within this region than the other VN-SBVs. In a phylogenetic analysis, the strains AmSBV-Viet4, AcSBV-Viet2, and AcSBV-Viet3 were clustered in group with AmSBV-UK, AmSBV-Kor21, and AmSBV-Kor19 strains. Whereas, the strains AmSBV-Viet6 and AcSBV-Viet7 clustered separately with the AcSBV strains from Korea and AcSBV-VietSBM2. And the strains AcSBV-Viet8, AcSBV-Viet1, AcSBV-Viet5, and AcSBV-Viet9 clustered with the AcSBV-India, AcSBV-Kor and AcSBV-VietSBM2. In a Simplot graph, the VN-SBVs diverged stronger in their ORF regions than in their 5' or 3' untranslated regions. The VN-SBVs possess genetic characteristics which are more similar to the Asian AcSBV strains than to AmSBV-UK strain. Taken together, our data indicate that host specificity, geographic distance, and viral cross-infections between different bee species may explain the genetic diversity among the VN-SBVs in A. cerana and A. mellifera and other SBV strains. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.
Chen, Yuting; Cassone, Bryan J.; Bai, Xiaodong; Redinbaugh, Margaret G.; Michel, Andrew P.
Background Leafhoppers (Hemiptera: Cicadellidae) are plant-phloem feeders that are known for their ability to vector plant pathogens. The black-faced leafhopper (Graminella nigrifrons) has been identified as the only known vector for the Maize fine streak virus (MFSV), an emerging plant pathogen in the Rhabdoviridae. Within G. nigrifrons populations, individuals can be experimentally separated into three classes based on their capacity for viral transmission: transmitters, acquirers and non-acquirers. Understanding the molecular interactions between vector and virus can reveal important insights in virus immune defense and vector transmission. Results RNA sequencing (RNA-Seq) was performed to characterize the transcriptome of G. nigrifrons. A total of 38,240 ESTs of a minimum 100 bp were generated from two separate cDNA libraries consisting of virus transmitters and acquirers. More than 60% of known D. melanogaster, A. gambiae, T. castaneum immune response genes mapped to our G. nigrifrons EST database. Real time quantitative PCR (RT-qPCR) showed significant down-regulation of three genes for peptidoglycan recognition proteins (PGRP – SB1, SD, and LC) in G. nigrifrons transmitters versus control leafhoppers. Conclusions Our study is the first to characterize the transcriptome of a leafhopper vector species. Significant sequence similarity in immune defense genes existed between G. nigrifrons and other well characterized insects. The down-regulation of PGRPs in MFSV transmitters suggested a possible role in rhabdovirus transmission. The results provide a framework for future studies aimed at elucidating the molecular mechanisms of plant virus vector competence. PMID:22808205
Full Text Available BACKGROUND: Leafhoppers (HEmiptera: Cicadellidae are plant-phloem feeders that are known for their ability to vector plant pathogens. The black-faced leafhopper (Graminella nigrifrons has been identified as the only known vector for the Maize fine streak virus (MFSV, an emerging plant pathogen in the Rhabdoviridae. Within G. nigrifrons populations, individuals can be experimentally separated into three classes based on their capacity for viral transmission: transmitters, acquirers and non-acquirers. Understanding the molecular interactions between vector and virus can reveal important insights in virus immune defense and vector transmission. RESULTS: RNA sequencing (RNA-Seq was performed to characterize the transcriptome of G. nigrifrons. A total of 38,240 ESTs of a minimum 100 bp were generated from two separate cDNA libraries consisting of virus transmitters and acquirers. More than 60% of known D. melanogaster, A. gambiae, T. castaneum immune response genes mapped to our G. nigrifrons EST database. Real time quantitative PCR (RT-qPCR showed significant down-regulation of three genes for peptidoglycan recognition proteins (PGRP - SB1, SD, and LC in G. nigrifrons transmitters versus control leafhoppers. CONCLUSIONS: Our study is the first to characterize the transcriptome of a leafhopper vector species. Significant sequence similarity in immune defense genes existed between G. nigrifrons and other well characterized insects. The down-regulation of PGRPs in MFSV transmitters suggested a possible role in rhabdovirus transmission. The results provide a framework for future studies aimed at elucidating the molecular mechanisms of plant virus vector competence.
Raghunath, Shobana; Pudupakam, Raghavendra Sumanth; Deventhiran, Jagadeeswaran; Tevatia, Rahul; Leroith, Tanya
Genetic lineages of swine influenza A viruses (SIVs) have recently been established in Turkeys in the United States. To identify molecular determinants that are involved in virulence and transmission of SIVs to Turkeys, we sequentially passaged two triple reassortant H3N2 SIV isolates from Minnesota in ten day old specific-pathogen free (SPF) Turkey embryos and tested them in seven-day old Turkey poults. We found that SIV replication in Turkey embryos led to minimal mutations in and around the receptor binding and antigenic sites of the HA molecule, while other gene segments were unchanged. The predominant changes associated with Turkey embryo passage were A223V, V226A and T248I mutations in the receptor-binding and glycosylation sites of the HA molecule. Furthermore, Turkey embryo propagation altered receptor specificity in SIV strain 07-1145. Embryo passaged 07-1145 virus showed a decrease in α2, 6 sialic acid receptor binding compared to the wild type virus. Intranasal infection of wild type SIVs in one-week-old Turkey poults resulted in persistent diarrhea and all the infected birds seroconverted at ten days post infection. The 07-1145 wild type virus also transmitted to age matched in-contact birds introduced one-day post infection. Turkeys infected with embryo passaged viruses displayed no clinical signs and were not transmitted to in-contact poults. Our results suggest that Turkey embryo propagation attenuates recent TR SIVs for infectivity and transmission in one week old Turkeys. Our findings will have important implications in identifying molecular determinants that control the transmission and virulence of TR SIVs in Turkeys and other species. Copyright © 2017 Elsevier B.V. All rights reserved.
Carrie A Manore
Full Text Available The recent spread of mosquito-transmitted viruses and associated disease to the Americas motivates a new, data-driven evaluation of risk in temperate population centers. Temperate regions are generally expected to pose low risk for significant mosquito-borne disease; however, the spread of the Asian tiger mosquito (Aedes albopictus across densely populated urban areas has established a new landscape of risk. We use a model informed by field data to assess the conditions likely to facilitate local transmission of chikungunya and Zika viruses from an infected traveler to Ae. albopictus and then to other humans in USA cities with variable human densities and seasonality. Mosquito-borne disease occurs when specific combinations of conditions maximize virus-to-mosquito and mosquito-to-human contact rates. We develop a mathematical model that captures the epidemiology and is informed by current data on vector ecology from urban sites. The model demonstrates that under specific but realistic conditions, fifty-percent of introductions by infectious travelers to a high human, high mosquito density city could initiate local transmission and 10% of the introductions could result in 100 or more people infected. Despite the propensity for Ae. albopictus to bite non-human vertebrates, we also demonstrate that local virus transmission and human outbreaks may occur when vectors feed from humans even just 40% of the time. Inclusion of human behavioral changes and mitigations were not incorporated into the models and would likely reduce predicted infections. This work demonstrates how a conditional series of non-average events can result in local arbovirus transmission and outbreaks of human disease, even in temperate cities.
Jelke J Fros
Full Text Available West Nile virus (WNV is a highly pathogenic flavivirus transmitted by Culex spp. mosquitoes. In North America (NA, lineage 1 WNV caused the largest outbreak of neuroinvasive disease to date, while a novel pathogenic lineage 2 strain circulates in southern Europe. To estimate WNV lineage 2 epidemic potential it is paramount to know if mosquitoes from currently WNV-free areas can support further spread of this epidemic.We assessed WNV vector competence of Culex pipiens mosquitoes originating from north-western Europe (NWE in direct comparison with those from NA. We exposed mosquitoes to infectious blood meals of lineage 1 or 2 WNV and determined the infection and transmission rates. We explored reasons for vector competence differences by comparing intrathoracic injection versus blood meal infection, and we investigated the influence of temperature. We found that NWE mosquitoes are highly competent for both WNV lineages, with transmission rates up to 25%. Compared to NA mosquitoes, transmission rates for lineage 2 WNV were significantly elevated in NWE mosquitoes due to better virus dissemination from the midgut and a shorter extrinsic incubation time. WNV infection rates further increased with temperature increase.Our study provides experimental evidence to indicate markedly different risk levels between both continents for lineage 2 WNV transmission and suggests a degree of genotype-genotype specificity in the interaction between virus and vector. Our experiments with varying temperatures explain the current localized WNV activity in southern Europe, yet imply further epidemic spread throughout NWE during periods with favourable climatic conditions. This emphasizes the need for intensified surveillance of virus activity in current WNV disease-free regions and warrants increased awareness in clinics throughout Europe.
Lan Anh, Nguyen Thi; Thanh, Dao Thi Ha; Hoan, Doan Huu; Thuy, Do Thu; Khong, Nguyen Viet; Anderson, Norman
At four times during November 2010, cattle with infections of Fasciola spp., in two communes of northern Vietnam, were allocated to two equivalent groups. Cattle in one group were treated with triclabendazole. Faecal samples collected monthly from both groups were tested for Fasciola copro-antigens and the presence of Fasciola eggs. Re-infection of treated cattle occurred from early March to late November, coinciding with high weekly totals of rainfall. Contamination of grazing areas by untreated cattle was high and relatively constant throughout the year. However, contamination was reduced to undetectable amounts for 8 to 12 weeks after treatment and even at 20 weeks was only 50% or less of the pre-treatment amounts. Therefore, treatments given in mid-September and again in early April, at the start of the wet season, may be sufficient to prevent contamination of grazing areas and reduce the prevalence and severity of Fasciola infections in cattle.
Audouze, Karine; Taboureau, Olivier; Grandjean, Philippe
The need to prevent developmental brain disorders has led to an increased interest in efficient neurotoxicity testing. When an epidemic of microcephaly occurred in Brazil, Zika virus infection was soon identified as the likely culprit. However, the pathogenesis appeared to be complex, and a larvi......The need to prevent developmental brain disorders has led to an increased interest in efficient neurotoxicity testing. When an epidemic of microcephaly occurred in Brazil, Zika virus infection was soon identified as the likely culprit. However, the pathogenesis appeared to be complex...... the potential developmental neurotoxicity, and we applied this method to examine the larvicide pyriproxyfen widely used in the prevention of Zika virus transmission. Our computational model covered a wide range of possible pathways providing mechanistic hypotheses between pyriproxyfen and neurological disorders...
Brookes, Sharon M; Nunez, Alejandor; Choudhury, Bhudipa
The declaration of the human influenza A pandemic (H1N1) 2009 (H1N1/09) raised important questions, including origin and host range [1,2]. Two of the three pandemics in the last century resulted in the spread of virus to pigs (H1N1, 1918; H3N2, 1968) with subsequent independent establishment...... and evolution within swine worldwide . A key public and veterinary health consideration in the context of the evolving pandemic is whether the H1N1/09 virus could become established in pig populations . We performed an infection and transmission study in pigs with A/California/07/09. In combination......, with clearly demonstrable pulmonary pathology, there was apparent selection of a virus variant with glycine (225G). These findings provide potential clues to the existence and biological significance of viral receptor-binding variants with 225D and 225G during the 1918 pandemic ....
WSSV upon transmission process at different route of transmission either through water, the cohabitation ant to cerithidae. A model has developed to fascilitate transmission through water. Aquarium capacity of 60 liter use in this research, each made into two compartment with separation by 3 different screen with pore sizes, 300μ, 700μ and 2 mm. Healthy tiger shrimp Penaeus monodon, reared in one compartment and artifitially diseased shrimp in another compartment. Cohabitation was done by rearing healthy shrimp of tiger shrimp and vannamei shrimp together with artifially infected shrimp with WSSV. For transmission through snails, snail fed with infected shrimp and reared together with infected live shrimp. Transmission also done through bathing healthy shrimp into water contained WSSV extract. The result showed that WSSV is able to cause infection in healthy shrimp eventhough are spaced apart from diseased shrimp using different mesh size screen. White spot virus can also be transmitted by cohabitation from diseased tiger shrimp either to tiger shrimp (same species or to vannamei shrimp (different species. The result showed that snail is not a career for WSSV. LT-50 of challenge of shrimp with WSSV through incubation with water contained of WSSV extract found that innocula at concentration 2,75 x 105 WSSV copy.μl-1 causing mortality at 50% within 108 hours. White screen, eventhough not fully efective, but still can retarded WSSV transmission. Result of study provide a greater understanding of how the virus be transmitted in the shrimp farm, and as guidance strategy in controlling in shrimp aquaculture. Keywords: disease, transmission of WSSV, cohabitation, shrimp, snail
Full Text Available Nhumirim virus (NHUV is an insect-specific virus that phylogenetically affiliates with dual-host mosquito-borne flaviviruses. Previous in vitro co-infection experiments demonstrated prior or concurrent infection of Aedes albopictus C6/36 mosquito cells with NHUV resulted in a 10,000-fold reduction in viral production of West Nile virus (WNV. This interference between WNV and NHUV was observed herein in an additional Ae. albopictus mosquito cell line, C7-10. A WNV 2K peptide (V9M mutant capable of superinfection with a pre-established WNV infection demonstrated a comparable level of interference from NHUV as the parental WNV strain in C6/36 and C7-10 cells. Culex quinquefasciatus and Culex pipiens mosquitoes intrathoracically inoculated with NHUVandWNV, or solely withWNVas a control, were allowed to extrinsically incubate the viruses up to nine and 14 days, respectively, and transmissibility and replication of WNV was determined. The proportion of Cx. quinquefasciatus mosquitoes capable of transmitting WNV was significantly lower for the WNV/NHUV group than the WNV control at seven and nine days post inoculation (dpi, while no differences were observed in the Cx. pipiens inoculation group. By dpi nine, a 40% reduction in transmissibility in mosquitoes from the dual inoculation group was observed compared to the WNV-only control. These data indicate the potential that infection of some Culex spp. vectors with NHUV could serve as a barrier for efficient transmissibility of flaviviruses associated with human disease.
When an arbo-virus enters a vector it will first enter the gut system of this insect before entering cells of the insect body. Once in the gut-system, arbo-viruses and gut microbiota can interact with each other. We wondered if different gut bacterial communities could influence virus infection of b...
Tomato necrotic dwarf virus (ToNDV); genus Torradovirus, is a whitefly-transmitted virus that caused significant losses for tomato production in the Imperial Valley of California during the 1980s. The virus causes severe stunting, dwarfing of leaves, foliar and fruit necrosis, and greatly reduced f...
Two highly pathogenic arthropod-borne (arbo)viruses, West Nile virus (WNV) and chikungunya virus (CHIKV), recently (re-)emerged in both Europe and the Americas. This resulted in large-scale epidemics of severe encephalitic and arthritogenic human disease,
Younai, Fariba S
Hepatitis B virus (HBV) infection rates are declining, but infection with this virus or hepatitis C virus (HCV) remains a risk for dental health care personnel (DHCP). This article describes the epidemiology of HBV and HCV and their particular risks to DHCP. Hepatitis B vaccination is discussed, as is postexposure management recommendations for both HBV and HCV. (c) 2010 Elsevier Inc. All rights reserved.
Oude Munnink, Bas B.; Phan, My V. T.; Simmonds, Peter; Koopmans, Marion P. G.; Kellam, Paul; van der Hoek, Lia; Cotten, Matthew
Porcine stool-associated RNA virus (posavirus), and Human stool-associated RNA virus (husavirus) are viruses in the order Picornavirales recently described in porcine and human fecal samples. The tentative group (Posa and Posa-like viruses: PPLVs) also includes fish stool-associated RNA virus
Ronde, Anthony de; Dooren, Maaike van; Hoek, Lian van der; Bouwhuis, Denise; Rooij, Esther de; Gemen, Bob van; Boer, R.J. de; Goudsmit, Jaap
Sequence analysis of human immunodeficiency virus type 1 (HIV-1) from 74 persons with acute infections identified eight strains with mutations in the reverse transcriptase (RT) gene at positions 41, 67, 68, 70, 215, and 219 associated with resistance to the nucleoside analogue zidovudine (AZT).
de Ronde, A.; van Dooren, M.; van der Hoek, L.; Bouwhuis, D.; de Rooij, E.; van Gemen, B.; de Boer, R.; Goudsmit, J.
Sequence analysis of human immunodeficiency virus type 1 (HIV-1) from 74 persons with acute infections identified eight strains with mutations in the reverse transcriptase (RT) gene at positions 41, 67, 68, 70, 215, and 219 associated with resistance to the nucleoside analogue zidovudine (AZT).
DULIEGE, AM; AMOS, CI; FELTON, S; BIGGAR, RJ; ZIEGLER, J; CRUIKSHANK, M; LEVY, J; MEATES, MA; GIBB, D; MAYAUX, MJ; TEGLAS, JP; LAURENT, C; BLANCHE, S; ROUZIOUX, C; HELLINGGIESE, G; MATTNER, U; HOEGER, PH; CONLON, T; GRIFFIN, E; DEMARIA, A; BENEDETTO, A; PRINCIPI, N; GIAQUINTO, C; GIANCOMELLI, A; MOK, J; CASABONA, J; FORTUNY, C; URIZ, S; PEREZ, JM; TUSETRUIZ, MC; LEON, P; ELORZA, JFY; CANOSA, C; BRANDLE, B; SEGER, R; NADAL, D; IRION, O; WYLER, CA; DAVIS, P; LALLEMANT, M; LALLEMANTLECOEUR, S; HITIMANA, DG; LEPAGE, P; VANDEPERRE, P; DABIS, F; MARUM, L; NDUGWA, C; TINDYEBWA, D; ACENG, E; MMIRO, F; SUTONGAS, T; OLNESS, K; LAPOINTE, N; RUBINSTEIN, A; BURGE, D; STECHENBERG, BW; COOPER, E; REGAN, AM; SHIPKOWITZ, S; WIZNIA, A; BRUNELL, PA; COURVILLE, T; RUTSTEIN, R; MCINTOSH, K; PETRU, A; OLEARY, M; CHURCH, J; TAYLOR, S; SQUIRES, J; MALLORY, M; YOGEV, R; RAKUSAN, T; PLUMLEY, S; SHELTON, MM; WILFERT, C; LANE, B; ABRAMS, EJ; RANA, S; CHANDAVASU, O; PUVABANDITSIN, S; CHOW, JH; SHAH, K; NACHMAN, S; ONEILL, R; SELWYN, P; SHOENBAUM, E; BARZILAI, A; WARFORD, R; AHERN, L; PAHWA, S; PNUGOTI, N; GARCIATRIAS, DE; BAKSHI, S; LANDESMAN, S; MENDEZ, H; MOROSO, G; MENDEZBAUTISTA, RD; FIKRIG, S; BELMAN, A; KLINE, MW; HANSON, C; EDELSON, P; HINDS, G; VANDYKE, R; CLARK, R; WARA, DW; MANIO, EB; JOHNSON, G; WELLS, L; JOHNSON, JP; ALGER, L; LUZURIAGA, K; MASTRUCCI, T; SUNKUTU, MR; RODRIGUEZ, Z; DOYLE, M; REUBEN, J; BRYSON, Y; DILLON, M; SIMPSON, BJ; ANDIMAN, W; URIBE, P; Klauke, B.
Background: We evaluated data from prospectively identified twins to understand better the mechanisms and covariates of mother-to-infant transmission of human immunodeficiency virus (HIV). Methods: Using data obtained from an international collaboration and multivariate quasilikelihood modeling, we
Nazir, Nausheen; Jan, Muhammad Rasul; Ali, Amjad; Asif, Muhammad; Idrees, Muhammad; Nisar, Mohammad; Zahoor, Muhammad; Abd El-Salam, Naser M
Hepatitis C virus (HCV) is a leading cause of chronic liver disease and frequently progresses towards liver cirrhosis and Hepatocellular Carcinoma (HCC). This study aimed to determine the prevalence of HCV genotypes and their association with possible transmission risks in the general population of Malakand Division. Sum of 570 serum samples were collected during March 2011 to January 2012 from suspected patients visited to different hospitals of Malakand. The suspected sera were tested using qualitative PCR and were then subjected to molecular genotype specific assay. Quantitative PCR was also performed for determination of pre-treatment viral load in confirmed positive patients. Out of 570 serum samples 316 sera were seen positive while 254 sera were found negative using qualitative PCR. The positive samples were then subjected to genotyping assay out of 316, type-specific PCR fragments were seen in 271 sera while 45 samples were found untypable genotypes. Genotype 3a was seen as a predominant genotype (63.3%) with a standard error of ±2.7%. Cramer's V statistic and Liklihood-Ratio statistical procedures are used to measure the strength and to test the association, respectively, between the dependent variable, genotype, and explanatory variables (e.g. gender, risk, age and area/districts). The dependent variable, genotype, is observed statistically significant association with variable risk factors. This implies that the genotype is highly dependent on how the patient was infected. In contrast, the other covariates, for example, gender, age, and district (area) no statistical significant association are observed. The association between gender-age indicates that the mean age of female was older by 10.5 ± 2.3 years with 95% confidence level using t-statistic. It was concluded from the present study that the predominant genotype was 3a in the infected population of Malakand. This study also highlights the high prevalence rate of untypable genotypes which an
Kawamura, Ryusuke; Shimura, Hanako; Mochizuki, Tomofumi; Ohki, Satoshi T; Masuta, Chikara
Asparagus virus 2 (AV-2) is a member of the genus Ilarvirus and thought to induce the asparagus decline syndrome. AV-2 is known to be transmitted by seed, and the possibility of pollen transmission was proposed 25 years ago but not verified. In AV-2 sequence analyses, we have unexpectedly found mixed infection by two distinct AV-2 isolates in two asparagus plants. Because mixed infections by two related viruses are normally prevented by cross protection, we suspected that pollen transmission of AV-2 is involved in mixed infection. Immunohistochemical analyses and in situ hybridization using AV-2-infected tobacco plants revealed that AV-2 was localized in the meristem and associated with pollen grains. To experimentally produce a mixed infection via pollen transmission, two Nicotiana benthamiana plants that were infected with each of two AV-2 isolates were crossed. Derived cleaved-amplified polymorphic sequence analysis identified each AV-2 isolate in the progeny seedlings, suggesting that pollen transmission could indeed result in a mixed infection, at least in N. benthamiana.
Maia A Rabaa
Full Text Available Dengue virus transmission occurs in both epidemic and endemic cycles across tropical and sub-tropical regions of the world. Incidence is particularly high in much of Southeast Asia, where hyperendemic transmission plagues both urban and rural populations. However, endemicity has not been established in some areas with climates that may not support year-round viral transmission. An understanding of how dengue viruses (DENV enter these environments and whether the viruses persist in inapparent local transmission cycles is central to understanding how dengue emerges in areas at the margins of endemic transmission. Dengue is highly endemic in tropical southern Vietnam, while increasingly large seasonal epidemics have occurred in northern Viet Nam over the last decade. We have investigated the spread of DENV-1 throughout Vietnam to determine the routes by which the virus enters northern and central regions of the country. Phylogeographic analysis of 1,765 envelope (E gene sequences from Southeast Asia revealed frequent movement of DENV between neighboring human populations and strong local clustering of viral lineages. Long-distance migration of DENV between human population centers also occurred regularly and on short time-scales, indicating human-mediated viral invasion into northern Vietnam. Human populations in southern Vietnam were found to be the primary source of DENV circulating throughout the country, while central and northern Vietnam acted as sink populations, likely due to reduced connectedness to other populations in the case of the central regions and to the influence of temperature variability on DENV replication and vector survival and competence in the north. Finally, phylogeographic analyses suggested that viral movement follows a gravity model and indicates that population immunity and physical and economic connections between populations may play important roles in shaping patterns of DENV transmission.
Rutledge, C Roxanne; Day, Jonathan F; Lord, Cynthia C; Stark, Lillian M; Tabachnick, Walter J
We describe the first documented field transmission of West Nile (WN) virus by a North American mosquito. WN was first detected in northern Florida in 2001. An intensive mosquito trapping and surveillance program was conducted in this region for four nights to assess mosquito transmission of WN. Four mosquito traps, each with a single sentinel chicken, were placed at five different locations on each of four nights. A total of 11,948 mosquitoes was collected, and 14 mosquito pools were found to contain WN, giving a minimum infection rate between 1.08 and 7.54 per 1,000. Only one of the 80 sentinel chickens seroconverted to WN, demonstrating a single mosquito transmission event during the study and a mosquito transmission rate of between 0.8 and 1 per 1,000. Culex nigripalpus Theobald was responsible for WN transmission to the sentinel chicken, although both Cx. nigripalpus and Culex quinquefasciatus Say were found infected with WN. Mosquito transmission rates are reported in this study for the first time for a WN outbreak. This information is essential to determine risk of human and animal infection.
Meo, S.A.; Abdo, A.A.; Baksh, N.D.; Sanie, F.M.
To determine an association between transmission of hepatitis B virus and secretor and non-secretor status of salivary blood group antigens. Study Design: Cross-sectional, analytical study. Place and Duration of Study: The Department of Physiology and Division of Hepatology, College of Medicine, King Khalid University Hospital, King Saud University, Riyadh, Kingdom of Saudi Arabia, from 2007 to 2009. Methodology: Eighty eight known patients, who were positive for Hepatitis B Surface Antigen [HBsAg] were recruited. Saliva was collected for investigating the secretor and non-secretor status by using blood typing kit number Kemtec Educational Science USA. Hepatitis B Surface antigen test was performed on Enzyme Linked Immunosorbent Assay technique. Polymerase chain reaction [PCR] on saliva was also carried out in High Performance Thermal Cycler-Palm- Cycler [Corbett Life Science, Sydney, Australia] and enzymatic amplification of extracted viral DNA was performed using primers covering the promoter of the core region of HBV. Results: Out of the 88 subjects, 61 belong to blood group O, 20 to A and 7 subjects to blood group B. Fifty subjects were secretors [salivary blood group antigens positive] and 38 subjects were non-secretors [salivary blood group antigens negative]. Among core gene positive 25 (69.4%) were secretors and 11 (30.6%) were non-secretors. However, in core gene negative 25 (48.1%) were secretors and 27 (51.9%) were non-secretors. Conclusion: The result shows an association [p=0.047] between secretor and non-secretors status of the salivary blood group antigens with core gene positive and core gene negative. (author)
Nyenswah, Tolbert; Blackley, David J; Freeman, Tabeh; Lindblade, Kim A; Arzoaquoi, Samson K; Mott, Joshua A; Williams, Justin N; Halldin, Cara N; Kollie, Francis; Laney, A Scott
On September 30, 2014, the Bong County health officer notified the county Ebola task force of a growing outbreak of Ebola virus disease (Ebola) in Mawah, a village of approximately 800 residents. During September 9-16, household quarantine had been used by the community in response to a new Ebola infection. Because the infection led to a local outbreak that grew during September 17-20, county authorities suggested community quarantine be considered, and beginning on approximately September 20, the Fuamah District Ebola Task Force (Task Force) engaged Mawah leaders to provide education about Ebola and to secure cooperation for the proposed measures. On September 30, Bong County requested technical assistance to develop strategies to limit transmission in the village and to prevent spread to other areas. The county health team, with support from the Task Force and CDC, traveled to Mawah on October 1 and identified approximately two dozen residents reporting symptoms consistent with Ebola. Because of an ambulance shortage, 2 days were required, beginning October 1, to transport the patients to an Ebola treatment unit in Monrovia. Community quarantine measures, consisting of restrictions on entering or leaving Mawah, regulated river crossings, and market closures, were implemented on October 1. Local leaders raised concerns about availability of medical care and food. The local clinic was reopened on October 11, and food was distributed on October 12. The Task Force reported a total of 22 cases of Ebola in Mawah during September 9-October 2, of which 19 were fatal. During October 3-November 21, no new cases were reported in the village. Involving community members during planning and implementation helped support a safe and effective community quarantine in Mawah.
Oliver J Brady
Full Text Available Dengue is a growing problem both in its geographical spread and in its intensity, and yet current global distribution remains highly uncertain. Challenges in diagnosis and diagnostic methods as well as highly variable national health systems mean no single data source can reliably estimate the distribution of this disease. As such, there is a lack of agreement on national dengue status among international health organisations. Here we bring together all available information on dengue occurrence using a novel approach to produce an evidence consensus map of the disease range that highlights nations with an uncertain dengue status.A baseline methodology was used to assess a range of evidence for each country. In regions where dengue status was uncertain, additional evidence types were included to either clarify dengue status or confirm that it is unknown at this time. An algorithm was developed that assesses evidence quality and consistency, giving each country an evidence consensus score. Using this approach, we were able to generate a contemporary global map of national-level dengue status that assigns a relative measure of certainty and identifies gaps in the available evidence.The map produced here provides a list of 128 countries for which there is good evidence of dengue occurrence, including 36 countries that have previously been classified as dengue-free by the World Health Organization and/or the US Centers for Disease Control. It also identifies disease surveillance needs, which we list in full. The disease extents and limits determined here using evidence consensus, marks the beginning of a five-year study to advance the mapping of dengue virus transmission and disease risk. Completion of this first step has allowed us to produce a preliminary estimate of population at risk with an upper bound of 3.97 billion people. This figure will be refined in future work.
Porta, Claudine; Spall, Valerie E.; Findlay, Kim C.; Gergerich, Rose C.; Farrance, Christine E.; Lomonossoff, George P.
Expression of foreign peptides on the surface of cowpea mosaic virus particles leads to the creation of chimaeras with a variety of phenotypes and yields. Two factors were shown to be particularly significant in determining the properties of a given chimaera: the length of the inserted sequence and its isoelectric point. The deleterious effect of high isoelectric point on the ability of chimeras to produce a systemic infection occurs irrespective of the site of insertion of the peptide. Ultrastructural analysis of tissue infected with chimaeras with different phenotypes showed that all produced particles with a tendency to aggregate, irrespective of the size or isoelectric point of the insert. Host range and transmission studies revealed that the expression of a foreign peptide did not (1) alter the virus host range, (2) increase the rate of transmission by beetles or through seed, or (3) change the insect vector specificity. These findings have implications for both the utility and the biosafety of Cowpea mosaic virus-based chimaeras
Although the Vietnam War ended more than thirty years ago, historians remain as divided on what happened as the American people were during the war. Mark Moyar maps the ongoing battle between "orthodox" and "revisionist" Vietnam War historians: the first group, those who depict Vietnam as a bad war that the United States should…
Schlosser, Josephine; Eiden, Martin; Vina-Rodriguez, Ariel; Fast, Christine; Dremsek, Paul; Lange, Elke; Ulrich, Rainer G; Groschup, Martin H
Hepatitis E virus (HEV) is the causative agent of acute hepatitis E in humans in developing countries, but sporadic and autochthonous cases do also occur in industrialised countries. In Europe, food-borne zoonotic transmission of genotype 3 (gt3) has been associated with domestic pig and wild boar. However, little is known about the course of HEV infection in European wild boar and their role in HEV transmission to domestic pigs. To investigate the transmissibility and pathogenesis of wild boar-derived HEVgt3, we inoculated four wild boar and four miniature pigs intravenously. Using quantitative real-time RT-PCR viral RNA was detected in serum, faeces and in liver, spleen and lymph nodes. The antibody response evolved after fourteen days post inoculation. Histopathological findings included mild to moderate lymphoplasmacytic hepatitis which was more prominent in wild boar than in miniature pigs. By immunohistochemical methods, viral antigens were detected mainly in Kupffer cells and liver sinusoidal endothelial cells, partially associated with hepatic lesions, but also in spleen and lymph nodes. While clinical symptoms were subtle and gross pathology was inconspicuous, increased liver enzyme levels in serum indicated hepatocellular injury. As the faecal-oral route is supposed to be the most likely transmission route, we included four contact animals to prove horizontal transmission. Interestingly, HEVgt3-infection was also detected in wild boar and miniature pigs kept in contact to intravenously inoculated wild boar. Given the high virus loads and long duration of viral shedding, wild boar has to be considered as an important HEV reservoir and transmission host in Europe.
Koopmans, M.; Wilbrink, B.; Conyn, M.; Natrop, G.; Nat, H. van der; Vennema, H.; Meijer, A.; Steenbergen, J. van; Fouchier, R.; Osterhaus, A.; Bosman, A.
BACKGROUND: An outbreak of highly pathogenic avian influenza A virus subtype H7N7 started at the end of February, 2003, in commercial poultry farms in the Netherlands. Although the risk of transmission of these viruses to humans was initially thought to be low, an outbreak investigation was launched
This study investigated the pathogenicity and transmissibility of a reverse-genetics derived highly pathogenic avian influenza (HPAI) H5N1 influenza A virus (IAV), A/Iraq/775/06, and a reassortant virus comprised of the HA and NA from A/Iraq/775/06 and the internal genes of a 2009 pandemic H1N1, A/N...
Hansen, Gert Helge; Delmas, B; Besnardeau, L
Aminopeptidase N is a species-specific receptor for transmissible gastroenteritis virus (TGEV), which infects piglets, and for the 229E virus, which infects humans. It is not known whether these coronaviruses are endocytosed before fusion with a membrane of the target cell, causing a productive...
Background APOBEC3 proteins are host factors that restrict infection by retroviruses like HIV, MMTV, and MLV and are variably expressed in hematopoietic and non-hematopoietic cells, such as macrophages, lymphocytes, dendritic, and epithelia cells. Previously, we showed that APOBEC3 expressed in mammary epithelia cells function to limit milk-borne transmission of the beta-retrovirus, mouse mammary tumor virus. In this present study, we used APOBEC3 knockout mice and their wild type counterpart to query the role of APOBEC3 in sexual transmission of LP-BM5 MLV – the etiological agent of murine AIDs (mAIDs). Results We show that mouse APOBEC3 is expressed in murine genital tract tissues and gametes and that genital tract tissue of APOBEC3-deficient mice are more susceptible to infection by LP-BM5 virus. APOBEC3 expressed in genital tract tissues most likely plays a role in decreasing virus transmission via the sexual route, since mice deficient in APOBEC3 gene have higher genitalia and seminal plasma virus load and sexually transmit the virus more efficiently to their partners compared to APOBEC3+ mice. Moreover, we show that female mice sexually infected with LP-BM5 virus transmit the virus to their off-spring in APOBEC3-dependent manner. Conclusion Our data indicate that genital tissue intrinsic APOBEC3 restricts genital tract infection and limits sexual transmission of LP-BM5 virus. PMID:22691411
Zeller, H G; Cornet, J P; Camicas, J L
Hyalomma (H.) marginatum rufipes ticks commonly infest birds and are potential vectors of Crimean-Congo hemorrhagic fever (CCHF) virus in west Africa. An experimental model for investigating the role of birds in the CCHF virus transmission cycle was developed. Following CCHF virus inoculation, antibodies were detected by enzyme-linked immunosorbent assay in one red-beaked hornbill and one glossy starling, but not in two laughing doves and six domestic chickens. None of the birds showed a detectable viremia. Hyalomma marginatum rufipes larvae were placed on three red-beaked hornbills and one glossy starling. These birds were then inoculated with CCHF virus (10(1.5) 50% mouse intracerebral lethal doses). Virus transmission to larvae or nymphs was obtained and seroconversions in birds were recorded. Virus was also detected in 90% of the individually tested nymphs, as well as in adults. The virus was then successfully transmitted by adult ticks to rabbits and the engorged females were allowed to oviposit. Progeny larvae were placed on another group of birds and one of three birds showed seroconversion. The cycle of transmission of virus between ticks and aviremic ground-feeding birds represent a potential reservoir and amplification mechanism of CCHF virus in west Africa.
Song, Daesub; Kang, Bokyu; Lee, Chulseung; Jung, Kwonil; Ha, Gunwoo; Kang, Dongseok; Park, Seongjun; Park, Bongkyun; Oh, Jinsik
In South Korea, where avian influenza virus subtypes H3N2, H5N1, H6N1, and H9N2 circulate or have been detected, 3 genetically similar canine influenza virus (H3N2) strains of avian origin (A/canine/Korea/01/2007, A/canine/Korea/02/2007, and A/canine/Korea/03/2007) were isolated from dogs exhibiting severe respiratory disease. To determine whether the novel canine influenza virus of avian origin was transmitted among dogs, we experimentally infected beagles with this influenza virus (H3N2) is...
Heiberg, Ida Louise; Hoegh, Mette; Ladelund, Steen
To explore the mechanism of horizontal transmission of hepatitis B virus (HBV) among children, we investigated the quantitative relationship between HBV in saliva and blood from 46 children with chronic hepatitis B. We found high levels of HBV DNA in saliva of HBeAg (+) children, suggesting saliva...... as a vehicle for horizontal transmission of HBV among children....
Leone, G.; Lindner, J.L.; Jongedijk, G.; Meer, van der F.
The successful back-transmission of the mechanically transmissible virus associated with apple stem pitting and pear vein yellows, from Nicotiana occidentalis to apple seedlings "Golden Delicious" under greenhouse conditions is reported. This result enabled a field experiment where isolates of apple
Full Text Available Banana bunchy top virus (BBTV is the most destructive pathogenic virus of banana plants worldwide. The virus is transmitted in a circulative non-propagative manner by the banana aphid, Pentalonia nigronervosa Coquerel. In this work, we examined the localization, accumulation, and transmission efficiency of BBTV in four laboratory-established lineages of Pentalonia aphids derived from four different host plants: taro (Colocasia esculenta, heliconia (Heliconia spp., red ginger (Alpinia purpurata, and banana (Musa sp.. Mitochondrial sequencing identified three and one lineages as Pentalonia caladii van der Goot, a recently proposed species, and P. nigronervosa, respectively. Microsatellite analysis separated the aphid lineages into four distinct genotypes. The transmission of BBTV was tested using leaf disk and whole-plant assays, both of which showed that all four lineages are competent vectors of BBTV, although the P. caladii from heliconia transmitted BBTV to the leaf disks at a significantly lower rate than did P. nigronervosa. The concentration of BBTV in dissected guts, haemolymph, and salivary glands was quantified by real-time PCR. The BBTV titer reached similar concentrations in the guts, haemolymph, and salivary glands of aphids from all four lineages tested. Furthermore, immunofluorescence assays showed that BBTV antigens localized to the anterior midguts and the principal salivary glands, demonstrating a similar pattern of translocations across the four lineages. The results reported in this study showed for the first time that P. caladii is a competent vector of BBTV.
Watanabe, Shizu; Greenwell, April M; Bressan, Alberto
Banana bunchy top virus (BBTV) is the most destructive pathogenic virus of banana plants worldwide. The virus is transmitted in a circulative non-propagative manner by the banana aphid, Pentalonia nigronervosa Coquerel. In this work, we examined the localization, accumulation, and transmission efficiency of BBTV in four laboratory-established lineages of Pentalonia aphids derived from four different host plants: taro (Colocasia esculenta), heliconia (Heliconia spp.), red ginger (Alpinia purpurata), and banana (Musa sp.). Mitochondrial sequencing identified three and one lineages as Pentalonia caladii van der Goot, a recently proposed species, and P. nigronervosa, respectively. Microsatellite analysis separated the aphid lineages into four distinct genotypes. The transmission of BBTV was tested using leaf disk and whole-plant assays, both of which showed that all four lineages are competent vectors of BBTV, although the P. caladii from heliconia transmitted BBTV to the leaf disks at a significantly lower rate than did P. nigronervosa. The concentration of BBTV in dissected guts, haemolymph, and salivary glands was quantified by real-time PCR. The BBTV titer reached similar concentrations in the guts, haemolymph, and salivary glands of aphids from all four lineages tested. Furthermore, immunofluorescence assays showed that BBTV antigens localized to the anterior midguts and the principal salivary glands, demonstrating a similar pattern of translocations across the four lineages. The results reported in this study showed for the first time that P. caladii is a competent vector of BBTV.
Thai, Pham Quang; Choisy, Marc; Duong, Tran Nhu; Thiem, Vu Dinh; Yen, Nguyen Thu; Hien, Nguyen Tran; Weiss, Daniel J; Boni, Maciej F; Horby, Peter
Experimental and ecological studies have shown the role of climatic factors in driving the epidemiology of influenza. In particular, low absolute humidity (AH) has been shown to increase influenza virus transmissibility and has been identified to explain the onset of epidemics in temperate regions. Here, we aim to study the potential climatic drivers of influenza-like illness (ILI) epidemiology in Vietnam, a tropical country characterized by a high diversity of climates. We specifically focus on quantifying and explaining the seasonality of ILI. We used 18 years (1993-2010) of monthly ILI notifications aggregated by province (52) and monthly climatic variables (minimum, mean, maximum temperatures, absolute and relative humidities, rainfall and hours of sunshine) from 67 weather stations across Vietnam. Seasonalities were quantified from global wavelet spectra, using the value of the power at the period of 1 year as a measure of the intensity of seasonality. The 7 climatic time series were characterized by 534 summary statistics which were entered into a regression tree to identify factors associated with the seasonality of AH. Results were extrapolated to the global scale using simulated climatic times series from the NCEP/NCAR project. The intensity of ILI seasonality in Vietnam is best explained by the intensity of AH seasonality. We find that ILI seasonality is weak in provinces experiencing weak seasonal fluctuations in AH (annual power power >17.6). In Vietnam, AH and ILI are positively correlated. Our results identify a role for AH in driving the epidemiology of ILI in a tropical setting. However, in contrast to temperate regions, high rather than low AH is associated with increased ILI activity. Fluctuation in AH may be the climate factor that underlies and unifies the seasonality of ILI in both temperate and tropical regions. Alternatively, the mechanism of action of AH on disease transmission may be different in cold-dry versus hot-humid settings
Joseni Santos da Conceição
profissionais (P = 0,018; P = 0,001 e P = 0,002, respectivamente. CONCLUSÕES: Observou-se a inadequação do conhecimento dos obstetras sobre as medidas eficazes para a detecção da infecção pelo vírus da hepatite B na gravidez e prevenção da transmissão vertical desse vírus para os recém-nascidos e a necessidade de educação continuada sobre as infecç��es passíveis de transmissão vertical.CONTEXT: Vertical transmission is responsible for 35%-40% of the new cases of hepatitis B worldwide and it is associated with an increased risk of chronic hepatitis B, cirrhosis and hepatocellular carcinoma. OBJECTIVE: To describe obstetricians' knowledge on the recommended measures to the diagnosis of the infection by the hepatitis virus B in pregnant women and to prevent the transmission of this infection to the babies of infected mothers. METHODS: Obstetricians registered at the "Sociedade de Ginecologia e Obstetrícia da Bahia", Salvador, BA, Brazil were randomly selected and invited to answer a questionnaire with questions regarding their academic formation, workplace, contact with medical students and their practices about the hepatitis virus B. Individuals who were not currently working as obstetricians or were not living in the state of Bahia were excluded from the study. Data were analyzed with the EpiInfo software with a 95% confidence interval. RESULTS: Three hundred and one obstetricians answered the questionnaire: 90.3% of them recognized that the hepatitis virus B could be transmitted vertically and 81.7% routinely screened their patients for hepatitis virus B infection during prenatal consultations; 66.0% considered HBsAg the best serological marker to be employed on the screening. Only 13.0% systematically recommended the vaccination against hepatitis virus B and the administration of immunoglobulin to the newborns of infected mothers in the first 12 hours of life. The frequency of correct answers about the vertical transmission of hepatitis virus B, the best
Rosso, Fernando; Pineda, Juan C; Sanz, Ana M; Cedano, Jorge A; Caicedo, Luis A
Dengue fever is a vector-transmitted viral infection. Non-vectorial forms of transmission can occur through organ transplantation. We reviewed medical records of donors and recipients with suspected dengue in the first post-transplant week. We used serologic and molecular analysis to confirm the infection. Herein, we describe four cases of dengue virus transmission through solid organ transplantation. The recipients had positive serology and RT-PCR. Infection in donors was detected through serology. All cases presented with fever within the first week after transplantation. There were no fatal cases. After these cases, we implemented dengue screening with NS1 antigen detection in donors during dengue outbreaks, and no new cases were detected. In the literature review, additional cases had been published through August 2017. Transmission of Dengue virus can occur through organ donation. In endemic regions, it is important to suspect and screen for dengue in febrile and thrombocytopenic recipients in the postoperative period. Copyright © 2018 Sociedade Brasileira de Infectologia. Published by Elsevier Editora Ltda. All rights reserved.
Perez de Leon, Adalberto A; Tabachnick, Walter J
Laboratory-reared Culicoides sonorensis Wirth & Jones were infected with vesicular stomatitis virus serotype New Jersey (family Rhabdoviridae, genus Vesiculovirus, VSNJV) through intrathoracic inoculation. After 10-d incubation at 25 degrees C, these insects were allowed to blood feed on four steers. Two other steers were exposed to VSNJV through intralingual inoculation with 10(8) tissue culture infective dose50 VSNJV. All six steers became seropositive for VSNJV. The results demonstrate the ability of C. sonorensis to transmit VSNJV to livestock. Only the animals intralingually inoculated with VSNJV showed clinical signs in the form of vesicles at the site of inoculation. Uninfected C. sonorensis allowed to feed on the exposed animals did not become infected with VSNJV. Animals infected by C. sonorensis showed a slower antibody response compared with intralingually inoculated animals. This is probably because of different amounts of virus received via insect transmission and syringe inoculation. A significant difference was found in the serum acute-phase protein alpha-1-acid glycoprotein in animals that received VSNJV through C. sonorensis transmission. These animals had previously been exposed to insect attack in the field compared with intralingually inoculated animals and C. sonorensis-infected animals that had been protected from insect attack. The failure to observe clinical signs of vesicular stomatitis through transmission of VSNJV by C. sonorensis may explain widespread subclinical infections during vesicular stomatitis epidemics.
Bertran, Kateri; Dolz, Roser; Busquets, Núria; Gamino, Virginia; Vergara-Alert, Júlia; Chaves, Aida J; Ramis, Antonio; Abad, F Xavier; Höfle, Ursula; Majó, Natàlia
European quail (Coturnix c. coturnix) may share with Japanese quail (Coturnix c. japonica) its potential as an intermediate host and reservoir of avian influenza viruses (AIV). To elucidate this question, European quail were experimentally challenged with two highly pathogenic AIV (HPAIV) (H7N1/HP and H5N1/HP) and one low pathogenic AIV (LPAIV) (H7N2/LP). Contact animals were also used to assess the viral transmission among birds. Severe neurological signs and mortality rates of 67% (H7N1/HP) and 92% (H5N1/HP) were observed. Although histopathological findings were present in both HPAIV-infected groups, H5N1/HP-quail displayed a broader viral antigen distribution and extent of microscopic lesions. Neither clinical nor pathological involvement was observed in LPAIV-infected quail. Consistent long-term viral shedding and effective transmission to naive quail was demonstrated for the three studied AIV. Drinking water arose as a possible transmission route and feathers as a potential origin of HPAIV dissemination. The present study demonstrates that European quail may play a major role in AI epidemiology, highlighting the need to further understand its putative role as an intermediate host for avian/mammalian reassortant viruses.
Schwartz, David A
-Pathology studies have been important in concluding that Zika virus infection occurring in pregnant women can result in vertical transmission of the agent from mother to fetus. Fetal and infant autopsies have provided crucial direct evidence that Zika virus can infect an unborn child, resulting in microcephaly, other malformations, and, in some cases, death. -To better understand the etiologic role and mechanism(s) of Zika virus in causing birth defects such as microcephaly, this communication analyzes the spectrum of clinical and autopsy studies reported from fetuses and infants who developed intrauterine Zika virus infection, and compares these findings with experimental data related to Zika virus infection. -Retrospective analysis of reported clinical, autopsy, pathology, and related postmortem studies from 9 fetuses and infants with intrauterine Zika virus infection and microcephaly. -All fetuses and infants examined demonstrated an overlapping spectrum of gross and microscopic neuropathologic abnormalities. Direct cytopathic effects of infection by the Zika virus were confined to the brain; in cases where other organs were evaluated, no direct viral effects were identified. -There is concordance of the spectrum of brain damage, reinforcing previous data indicating that the Zika virus has a strong predilection for cells of the fetal central nervous system following vertical transmission. The occurrence of additional congenital abnormalities suggests that intrauterine brain damage from Zika virus interferes with normal fetal development, resulting in fetal akinesia. Experimental in vitro and in vivo studies of Zika virus infection corroborate the human autopsy findings of neural specificity.
de Ronde, A; van Dooren, M; van Der Hoek, L; Bouwhuis, D; de Rooij, E; van Gemen, B; de Boer, R; Goudsmit, J
Sequence analysis of human immunodeficiency virus type 1 (HIV-1) from 74 persons with acute infections identified eight strains with mutations in the reverse transcriptase (RT) gene at positions 41, 67, 68, 70, 215, and 219 associated with resistance to the nucleoside analogue zidovudine (AZT). Follow-up of the fate of these resistant HIV-1 strains in four newly infected individuals revealed that they were readily replaced by sensitive strains. The RT of the resistant viruses changed at amino acid 215 from tyrosine (Y) to aspartic acid (D) or serine (S), with asparagine (N) as a transient intermediate, indicating the establishment of new wild types. When we introduced these mutations and the original threonine (T)-containing wild type into infectious molecular clones and assessed their competitive advantage in vitro, the order of fitness was in accord with the in vivo observations: 215Y types with D, S, or N residues at position 215 may be warranted in order to estimate the threat to long-term efficacy of regimens including nucleoside analogues.
Previous US Public Health Service recommendations pertaining to sexual, IV drug abuse, and perinatal transmission of human-T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) have been published. Reduction of sexual and IV transmission of HTLV-III/LAV should be enhanced by using available serologic tests to give asymptomatic, infected individuals in high-risk groups the opportunity to know their status so they can take appropriate steps to prevent the further transmission of this virus. Since the objective of these additional recommendations is to help interrupt transmission by encouraging testing and counseling among persons in high-risk groups, careful attention must be paid to maintaining confidentiality and to protecting records from any unauthorized disclosure. The ability of health departments to assure confidentiality, and the public confidence in that ability, are crucial to efforts to increase the number of persons requesting such testing and counseling. Persons at increased risk of HTLV-III/LAV infection include: homosexual and bisexual men; present or past IV drug abusers; persons with clinical or laboratory evidence of infection, such as those with signs or symptoms compatible with acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC); persons born in countries where heterosexual transmission is thought to play a major role; male or female prostitutes and their sex partners; sex partners of infected persons or persons at increased risk; all persons with hemophilia who have received clotting-factor products; and newborn infants of high-risk or infected mothers. Recommendations include: community health education programs should be aimed at members of high-risk groups to increase knowledge of AIDS, to facilitate behavioral changes to reduce risks of HTLV-III/LAV infection, and encourage voluntary testing and counseling; counseling and voluntary serologic testing for HTLV-III/LAV should be routinely offered to
Ma, Mai-Juan; Wang, Guo-Lin; Anderson, Benjamin D; Bi, Zhen-Qiang; Lu, Bing; Wang, Xian-Jun; Wang, Chuang-Xin; Chen, Shan-Hui; Qian, Yan-Hua; Song, Shao-Xia; Li, Min; Lednicky, John A; Zhao, Teng; Wu, Meng-Na; Cao, Wu-Chun; Gray, Gregory C
Our understanding of influenza A virus transmission between humans and pigs is limited. Beginning in 2015, we used a One Health approach and serial sampling to prospectively study 299 swine workers and 100 controls, their 9000 pigs, and 6 pig farm environments in China for influenza A viruses (IAVs) using molecular, culture, and immunological techniques. Study participants were closely monitored for influenza-like illness (ILI) events. Upon enrollment, swine workers had higher serum neutralizing antibody titers against swine H1N1 and higher nasal wash total immunoglobulin A (IgA) and specific IgA titers against swine H1N1 and H3N2 viruses. Over a period of 12 months, IAVs were detected by quantitative reverse-transcription polymerase chain reaction in 46 of 396 (11.6%) environmental swabs, 235 of 3300 (7.1%) pig oral secretion, 23 of 396 (5.8%) water, 20 of 396 (5.1%) aerosol, and 19 of 396 (4.8%) fecal-slurry specimens. Five of 32 (15.6%) participants with ILI events had nasopharyngeal swab specimens that were positive for IAV, and 17 (53.1%) demonstrated 4-fold rises in neutralization titers against a swine virus. Reassorted Eurasian avian-lineage H1N1, A(H1N1)pdm09-like, and swine-lineage H3N2 viruses were identified in pig farms. The A(H1N1)pdm09-like H1N1 viruses identified in swine were nearly genetically identical to the human H1N1 viruses isolated from the participants with ILI. There was considerable evidence of A(H1N1)pdm09-like, swine-lineage H1N1, and swine-lineage H3N2 viruses circulating, likely reassorting, and likely crossing species within the pig farms. These data suggest that stronger surveillance for novel influenza virus emergence within swine farms is imperative. © The Author(s) 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: firstname.lastname@example.org.
Facchini, Marzia; Spagnolo, Domenico; De Marco, Maria A.; Calzoletti, Laura; Zanetti, Alessandro; Fumagalli, Roberto; Tanzi, Maria L.; Cassone, Antonio; Rezza, Giovanni; Donatelli, Isabella
A pandemic (H1N1) 2009 virus strain carrying the D222G mutation was identified in a severely ill man and was transmitted to a household contact. Only mild illness developed in the contact, despite his obesity and diabetes. The isolated virus reacted fully with an antiserum against the pandemic vaccine strain. PMID:20409386
Bravo-Vasquez, Nicolás; Karlsson, Erik A; Jimenez-Bluhm, Pedro; Meliopoulos, Victoria; Kaplan, Bryan; Marvin, Shauna; Cortez, Valerie; Freiden, Pamela; Beck, Melinda A; Hamilton-West, Christopher; Schultz-Cherry, Stacey
Phylogenetic analysis of the influenza hemagglutinin gene (HA) has suggested that commercial pigs in Chile harbor unique human seasonal H1-like influenza viruses, but further information, including characterization of these viruses, was unavailable. We isolated influenza virus (H1N2) from a swine in a backyard production farm in Central Chile and demonstrated that the HA gene was identical to that in a previous report. Its HA and neuraminidase genes were most similar to human H1 and N2 viruses from the early 1990s and internal segments were similar to influenza A(H1N1)pdm09 virus. The virus replicated efficiently in vitro and in vivo and transmitted in ferrets by respiratory droplet. Antigenically, it was distinct from other swine viruses. Hemagglutination inhibition analysis suggested that antibody titers to the swine Chilean H1N2 virus were decreased in persons born after 1990. Further studies are needed to characterize the potential risk to humans, as well as the ecology of influenza in swine in South America.
Individual avian influenza (AI) virus strains vary in their ability to infect, transmit and cause disease and death in different bird species. Low pathogenicity AI (LPAI) viruses are maintained in wild birds, and must be adapted to pass to domestic poultry, where they replicate in respiratory and in...
Fordyce, Sarah Louise; Bragstad, Karoline; Pedersen, Svend Stenvang
Influenza viruses such as swine-origin influenza A(H1N1) virus (A(H1N1)pdm09) generate genetic diversity due to the high error rate of their RNA polymerase, often resulting in mixed genotype populations (intra-host variants) within a single infection. This variation helps influenza to rapidly res...
Dekker, A.; Vernooij, J.C.M.; Bouma, A.; Stegeman, J.A.
Upon infection with foot-and-mouth disease virus (FMDV) a considerable number of animals become carriers of the virus. These carriers are considered to be a risk for new outbreaks, but the rate at which these animals can transmit the infection has not been quantified. An analysis was carried out
Vloet, Rianka P.M.; Vogels, Chantal B.F.; Koenraadt, Constantianus J.M.; Pijlman, Gorben P.; Eiden, Martin; Gonzales, Jose L.; Keulen, van Lucien J.M.; Wichgers Schreur, Paul J.; Kortekaas, Jeroen
Background: Rift Valley fever virus (RVFV) is a mosquito-borne bunyavirus of the genus Phlebovirus that is highly pathogenic to ruminants and humans. The disease is currently confined to Africa and the Arabian Peninsula, but globalization and climate change may facilitate introductions of the virus
Mossoun, Arsène; Calvignac-Spencer, Sébastien; Anoh, Augustin E; Pauly, Maude S; Driscoll, Daniel A; Michel, Adam O; Nazaire, Lavry Grah; Pfister, Stefan; Sabwe, Pascale; Thiesen, Ulla; Vogler, Barbara R; Wiersma, Lidewij; Muyembe-Tamfum, Jean-Jacques; Karhemere, Stomy; Akoua-Koffi, Chantal; Couacy-Hymann, Emmanuel; Fruth, Barbara; Wittig, Roman M; Leendertz, Fabian H; Schubert, Grit
Simian T-lymphotropic virus 1 (STLV-1) enters human populations through contact with nonhuman primate (NHP) bushmeat. We tested whether differences in the extent of contact with STLV-1-infected NHP bushmeat foster regional differences in prevalence of human T-lymphotropic virus 1 (HTLV-1). Using serological and PCR assays, we screened humans and NHPs at two Sub-Saharan African sites where subsistence hunting was expected to be less (Taï region, Côte d'Ivoire [CIV]) or more (Bandundu region, Democratic Republic of the Congo [DRC]) developed. Only 0.7% of human participants were infected with HTLV-1 in CIV ( n = 574), and 1.3% of humans were infected in DRC ( n = 302). Two of the Ivorian human virus sequences were closely related to simian counterparts, indicating ongoing zoonotic transmission. Multivariate analysis of human demographic parameters and behavior confirmed that participants from CIV were less often exposed to NHPs than participants from DRC through direct contact, e.g., butchering. At the same time, numbers of STLV-1-infected NHPs were higher in CIV (39%; n = 111) than in DRC (23%; n = 39). We conclude that similar ultimate risks of zoonotic STLV-1 transmission-defined as the product of prevalence in local NHP and human rates of contact to fresh NHP carcasses-contribute to the observed comparable rates of HTLV-1 infection in humans in CIV and DRC. We found that young adult men and mature women are most likely exposed to NHPs at both sites. In view of the continued difficulties in controlling zoonotic disease outbreaks, the identification of such groups at high risk of NHP exposure may guide future prevention efforts. IMPORTANCE Multiple studies report a high risk for zoonotic transmission of blood-borne pathogens like retroviruses through contact with NHPs, and this risk seems to be particularly high in tropical Africa. Here, we reveal high levels of exposure to NHP bushmeat in two regions of Western and Central tropical Africa. We provide evidence
Tong, Shilu; Dale, Pat; Nicholls, Neville; Mackenzie, John S.; Wolff, Rodney; McMichael, Anthony J.
Background Arbovirus diseases have emerged as a global public health concern. However, the impact of climatic, social, and environmental variability on the transmission of arbovirus diseases remains to be determined. Objective Our goal for this study was to provide an overview of research development and future research directions about the interrelationship between climate variability, social and environmental factors, and the transmission of Ross River virus (RRV), the most common and widespread arbovirus disease in Australia. Methods We conducted a systematic literature search on climatic, social, and environmental factors and RRV disease. Potentially relevant studies were identified from a series of electronic searches. Results The body of evidence revealed that the transmission cycles of RRV disease appear to be sensitive to climate and tidal variability. Rainfall, temperature, and high tides were among major determinants of the transmission of RRV disease at the macro level. However, the nature and magnitude of the interrelationship between climate variability, mosquito density, and the transmission of RRV disease varied with geographic area and socioenvironmental condition. Projected anthropogenic global climatic change may result in an increase in RRV infections, and the key determinants of RRV transmission we have identified here may be useful in the development of an early warning system. Conclusions The analysis indicates that there is a complex relationship between climate variability, social and environmental factors, and RRV transmission. Different strategies may be needed for the control and prevention of RRV disease at different levels. These research findings could be used as an additional tool to support decision making in disease control/surveillance and risk management. PMID:19079707
Luk, Geraldine S. M.; Leung, Connie Y. H.; Sia, Sin Fun; Choy, Ka-Tim; Zhou, Jie; Ho, Candy C. K.; Cheung, Peter P. H.; Lee, Elaine F.; Wai, Chris K. L.; Li, Pamela C. H.; Ip, Sin-Ming; Poon, Leo L. M.; Lindsley, William G.
ABSTRACT Poultry exposure is a major risk factor for human H7N9 zoonotic infections, for which the mode of transmission remains unclear. We studied the transmission of genetically related poultry and human H7N9 influenza viruses differing by four amino acids, including the host determinant PB2 residue 627. A/Silkie chicken/HK/1772/2014 (SCk1772) and A/HK/3263/14 (HK3263) replicated to comparable titers in chickens, with superior oropharyngeal over cloacal shedding; both viruses transmitted efficiently among chickens via direct contact but inefficiently via the airborne route. Interspecies transmission via the airborne route was observed for ferrets exposed to the SCk1772- or HK3263-infected chickens, while low numbers of copies of influenza viral genome were detected in the air, predominantly at particle sizes larger than 4 μm. In ferrets, the human isolate HK3263 replicated to higher titers and transmitted more efficiently via direct contact than SCk1772. We monitored “intrahost” and “interhost” adaptive changes at PB2 residue 627 during infection and transmission of the Sck1772 that carried E627 and HK3263 that carried V/K/E polymorphism at 60%, 20%, and 20%, respectively. For SCk1772, positive selection for K627 over E627 was observed in ferrets during the chicken-to-ferret or ferret-to-ferret transmission. For HK3263 that contained V/K/E polymorphism, mixed V627 and E627 genotypes were transmitted among chickens while either V627 or K627 was transmitted to ferrets with a narrow transmission bottleneck. Overall, our results suggest direct contact as the main mode for H7N9 transmission and identify the PB2-V627 genotype with uncompromised fitness and transmissibility in both avian and mammalian species. IMPORTANCE We studied the modes of H7N9 transmission, as this information is crucial for developing effective control measures for prevention. Using chicken (SCk1772) and human (HK3263) H7N9 isolates that differed by four amino acids, including the host
Pham, Quang Duy; Wilson, David P; Nguyen, Thuong Vu; Do, Nhan Thi; Truong, Lien Xuan; Nguyen, Long Thanh; Zhang, Lei
The objective of this study was to investigate the potential epidemiological impact of viral load (VL) monitoring and its cost-effectiveness in Vietnam, where transmitted HIV drug resistance (TDR) prevalence has increased from HIV drug-resistance tests. We assessed the cost per disability-adjusted life year (DALY) averted for each scenario. Projecting expected ART scale-up levels, to approximately double the number of people on ART by 2030, will lead to an estimated 18 510 cases (95% CI: 9120-34 600 cases) of TDR and 55 180 cases (95% CI: 40 540-65 900 cases) of acquired drug resistance (ADR) in the absence of VL monitoring. This projection corresponds to a TDR prevalence of 16% (95% CI: 11%-24%) and ADR of 18% (95% CI: 15%-20%). Annual or biennial VL monitoring with 30% coverage is expected to relieve 12%-31% of TDR (2260-5860 cases), 25%-59% of ADR (9620-22 650 cases), 2%-6% of HIV-related deaths (360-880 cases) and 19 270-51 400 DALYs during 2015-30. The 30% coverage of VL monitoring is estimated to cost US$4848-5154 per DALY averted. The projected additional cost for implementing this strategy is US$105-268 million over 2015-30. Our study suggests that a programmatically achievable 30% coverage of VL monitoring can have considerable benefits for individuals and leads to population health benefits by reducing the overall national burden of HIV drug resistance. It is marginally cost-effective according to common willingness-to-pay thresholds. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: email@example.com.
Full Text Available Zika virus (ZIKV was recently declared as a ‘Global Health Emergency’ by the World Health Organization. Various tissue reservoirs of ZIKV in infected humans and animals models have been observed, the implications of which are not known. Compared to other Flaviviruses, sexual transmission and persistence in the genitourinary tract seem to be unique to ZIKV. ZIKV persistence and shedding in bodily secretions (e.g. saliva, semen is a concern for potential disease spread and could pose challenges in diagnosis, regulatory guidelines and drug/vaccine development. Murine and non-human primate models could be useful to study the role of tissue reservoirs in the development of prophylactic or therapeutic strategies. There is a need for meta-analysis of the ZIKV infection and virus shedding data from infected patients and ZIKV animal models, and additional research is needed to fully comprehend the long term implications of tissue reservoirs on ZIKV disease pathogenesis and biology.
Bricault, Christine A.; Perry, Keith L.
In the atomic model of Cucumber mosaic virus (CMV), six amino acid residues form stabilizing salt bridges between subunits of the asymmetric unit at the quasi-threefold axis of symmetry. To evaluate the effects of these positions on virion stability and aphid vector transmissibility, six charged amino acid residues were individually mutated to alanine. All of the six engineered viruses were viable and exhibited near wild type levels of virion stability in the presence of urea. Aphid vector transmissibility was nearly or completely eliminated in the case of four of the mutants; two mutants demonstrated intermediate aphid transmissibility. For the majority of the engineered mutants, second-site mutations were observed following aphid transmission and/or mechanical passaging, and one restored transmission rates to that of the wild type. CMV capsids tolerate disruption of acid–base pairing interactions at the quasi-threefold axis of symmetry, but these interactions are essential for maintaining aphid vector transmissibility. - Highlights: ► Amino acids between structural subunits of Cucumber mosaic virus affect vector transmission. ► Mutant structural stability was retained, while aphid vector transmissibility was disrupted. ► Spontaneous, second-site mutations restored aphid vector transmissibility
Bricault, Christine A. [Department of Plant Pathology and Plant-Microbe Biology, 334 Plant Science Building, Cornell University, Ithaca, NY 14850 (United States); Perry, Keith L., E-mail: KLP3@cornell.edu [Department of Plant Pathology and Plant-Microbe Biology, 334 Plant Science Building, Cornell University, Ithaca, NY 14850 (United States)
In the atomic model of Cucumber mosaic virus (CMV), six amino acid residues form stabilizing salt bridges between subunits of the asymmetric unit at the quasi-threefold axis of symmetry. To evaluate the effects of these positions on virion stability and aphid vector transmissibility, six charged amino acid residues were individually mutated to alanine. All of the six engineered viruses were viable and exhibited near wild type levels of virion stability in the presence of urea. Aphid vector transmissibility was nearly or completely eliminated in the case of four of the mutants; two mutants demonstrated intermediate aphid transmissibility. For the majority of the engineered mutants, second-site mutations were observed following aphid transmission and/or mechanical passaging, and one restored transmission rates to that of the wild type. CMV capsids tolerate disruption of acid–base pairing interactions at the quasi-threefold axis of symmetry, but these interactions are essential for maintaining aphid vector transmissibility. - Highlights: ► Amino acids between structural subunits of Cucumber mosaic virus affect vector transmission. ► Mutant structural stability was retained, while aphid vector transmissibility was disrupted. ► Spontaneous, second-site mutations restored aphid vector transmissibility.
Belser, Jessica A; Creager, Hannah M; Zeng, Hui; Maines, Taronna R; Tumpey, Terrence M
H7 subtype influenza viruses represent a persistent public health threat because of their continued detection in poultry and ability to cause human infection. An outbreak of highly pathogenic avian influenza H7N7 virus in Italy during 2013 resulted in 3 cases of human conjunctivitis. We determined the pathogenicity and transmissibility of influenza A/Italy/3/2013 virus in mouse and ferret models and examined the replication kinetics of this virus in several human epithelial cell types. The moderate virulence observed in mammalian models and the capacity for transmission in a direct contact model underscore the need for continued study of H7 subtype viruses. Published by Oxford University Press for the Infectious Diseases Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.
Full Text Available Rift Valley fever is an acute, zoonotic viral disease of domestic ruminants, caused by a phlebovirus (Bunyaviridae family. A large outbreak occurred in Madagascar in 2008-2009. The goal of the present study was to evaluate the point prevalence of antibodies against Rift Valley Fever Virus (RVFV in cattle in the Anjozorobe district, located in the wet and temperate highland region of Madagascar and yet heavily affected by the disease, and analyse environmental and trade factors potentially linked to RVFV transmission. A serological study was performed in 2009 in 894 bovines. For each bovine, the following variables were recorded: age, location of the night pen, minimum distance from the pen to the nearest water point and the forest, nearest water point type, and herd replacement practices. The serological data were analyzed using a generalized linear mixed model. The overall anti-RVFV IgG seroprevalence rate was 28% [CI95% 25-31]. Age was statistically linked to prevalence (p = 10(-4, being consistent with a recurrent RVFV circulation. Distance from the night pen to the nearest water point was a protective factor (p = 5.10(-3, which would be compatible with a substantial part of the virus transmission being carried out by nocturnal mosquito vectors. However, water point type did not influence the risk of infection: several mosquito species are probably involved. Cattle belonging to owners who purchase animals to renew the herd were significantly more likely to have seroconverted than others (p = 0.04: cattle trade may contribute to the introduction of the virus in this area. The minimum distance of the night pen to the forest was not linked to the prevalence. This is the first evidence of a recurrent transmission of RVFV in such an ecosystem that associates a wet, temperate climate, high altitude, paddy fields, and vicinity to a dense rain forest. Persistence mechanisms need to be further investigated.
Paul, P S; Mengeling, W L
An attenuated strain NADL-2 of porcine parvovirus (PPV) has been used at the 54th cell culture passage as a modified live-virus (MLV) vaccine. The present study was conducted to determine the minimum immunizing dose of MLV, the extent of MLV multiplication in swine tissues, and its transmission from swine administered MLV oronasally or intramuscularly. Immune response to MLV was dose dependent and swine responded to as little as 10(2) median cell-culture infective doses (CCID50). A 10(5) CCID50 of MLV, the largest dose given, induced the best immune response and was used in subsequent experiments. Route of MLV administration also was found to be important. The MLV replicated in tissues of swine after IM inoculation; however, viral antigen in tissues was less, as measured by immunofluorescence, and serum hemagglutination-inhibition titers for PPV were lower in MLV-inoculated swine than we have previously observed in virulent PPV-inoculated swine. In contrast, oronasal inoculation with MLV did not consistently result in infection of pigs; only 5 of 23 swine had virologic and/or serologic evidence of infection. Virus transmission studies indicated that MLV is shed in feces, but shedding occurs later than that in virulent-PPV-inoculated swine and is inconsistent. Delayed transmission of MLV was observed in contact pigs, which were seronegative at 2 weeks, but became seropositive at 4 weeks--indicating that perhaps a virus population capable of infecting pigs by oronasal route was selected by passage through the pig.(ABSTRACT TRUNCATED AT 250 WORDS)
Wilson-Rothering, Anna; Marcquenski, Susan; Koenigs, Ryan P.; Bruch, Ronald; Kamke, Kendall; Isermann, Daniel A.; Thurman, Andrew; Toohey-Kurth, Kathy; Goldberg, Tony
Viral hemorrhagic septicemia virus (VHSV) is an emerging pathogen that causes mass mortality in multiple fish species. In 2007, the Great Lakes freshwater strain, type IVb, caused a large die-off of freshwater drum (Aplodinotus grunniens) in Lake Winnebago, Wisconsin, USA. To evaluate the persistence and transmission of VHSV, freshwater drum from Lake Winnebago were tested for antibodies to the virus using recently developed virus neutralization (VN) and enzyme-linked immunosorbent (ELISA) assays. Samples were also tested by real-time reverse transcription-PCR (rRT-PCR) to detect viral RNA. Of 548 serum samples tested, 44 (8.03%) were positive by VN (titers ranging from 1:16 to 1:1,024) and 45 (8.21%) were positive by ELISA, including 7 fish positive by both assays. Antibody prevalence increased with age and was higher in one northwestern area of Lake Winnebago than in other areas. Of 3,864 tissues sampled from 551 fish, 1 spleen and 1 kidney sample from a single adult female fish collected in the spring of 2012 tested positive for VHSV by rRT-PCR, and serum from the same fish tested positive by VN and ELISA. These results suggest that VHSV persists and viral transmission may be active in Lake Winnebago even in years following outbreaks and that wild fish may survive VHSV infection and maintain detectable antibody titers while harboring viral RNA. Influxes of immunologically naive juvenile fish through recruitment may reduce herd immunity, allow VHSV to persist, and drive superannual cycles of transmission that may sporadically manifest as fish kills.
Adam J Kucharski
Full Text Available Between October 2013 and April 2014, more than 30,000 cases of Zika virus (ZIKV disease were estimated to have attended healthcare facilities in French Polynesia. ZIKV has also been reported in Africa and Asia, and in 2015 the virus spread to South America and the Caribbean. Infection with ZIKV has been associated with neurological complications including Guillain-Barré Syndrome (GBS and microcephaly, which led the World Health Organization to declare a Public Health Emergency of International Concern in February 2015. To better understand the transmission dynamics of ZIKV, we used a mathematical model to examine the 2013-14 outbreak on the six major archipelagos of French Polynesia. Our median estimates for the basic reproduction number ranged from 2.6-4.8, with an estimated 11.5% (95% CI: 7.32-17.9% of total infections reported. As a result, we estimated that 94% (95% CI: 91-97% of the total population of the six archipelagos were infected during the outbreak. Based on the demography of French Polynesia, our results imply that if ZIKV infection provides complete protection against future infection, it would take 12-20 years before there are a sufficient number of susceptible individuals for ZIKV to re-emerge, which is on the same timescale as the circulation of dengue virus serotypes in the region. Our analysis suggests that ZIKV may exhibit similar dynamics to dengue virus in island populations, with transmission characterized by large, sporadic outbreaks with a high proportion of asymptomatic or unreported cases.
Paintsil, Elijah; He, Huijie; Peters, Christopher; Lindenbach, Brett D.; Heimer, Robert
Background We hypothesized that the high prevalence of HCV among injection drug users (IDUs) might be due to prolonged virus survival in contaminated syringes. Methods We developed a microculture assay to examine the viability of HCV. Syringes were loaded with blood spiked with HCV reporter virus (Jc1/GLuc2A) to simulate two scenarios of residual volumes; low (2 μl) void volume for 1-ml insulin syringes, and high (32 μl) void volume for 1-ml tuberculin syringes. Syringes were stored at 4°C, 22°C, and 37°C for up to 63 days before testing for HCV infectivity using luciferase activity. Results The virus decay rate was biphasic (t½ α = 0.4h and t½β = 28h). Insulin syringes failed to yield viable HCV beyond day one at all storage temperatures except for 4o in which 5% of syringes yielded viable virus on day 7. Tuberculin syringes yielded viable virus from 96%, 71%, and 52% of syringes following storage at 4o, 22° and 37o for 7 days, respectively, and yielded viable virus up to day 63. Conclusions The high prevalence of HCV among IDUs may be partly due to the resilience of the virus and the syringe type. Our findings may be used to guide prevention strategies. PMID:20726768
J. Scott Foott
Full Text Available The dynamics of IHNV infection and disease were followed in a juvenile Chinook salmon population both during hatchery rearing and for two weeks post-release. Cumulative weekly mortality increased from 0.03%–3.5% as the prevalence of viral infection increased from 2%–22% over the same four-week period. The majority of the infected salmon was asymptomatic. Salmon demonstrating clinical signs of infection shed 1000 pfu mL-1 of virus into the water during a 1 min observation period and had a mean concentration of 106 pfu mL-1 in their mucus. The high virus concentration detected in mucus suggests that it could act as an avenue of transmission in high density situations where dominance behavior results in nipping. Infected smolts that had migrated 295 km down river were collected at least two weeks after their release. The majority of the virus positive smolts was asymptomatic. A series of transmission experiments was conducted using oral application of the virus to simulate nipping, brief low dose waterborne challenges, and cohabitation with different ratios of infected to naïve fish. These studies showed that asymptomatic infections will occur when a salmon is exposed for as little as 1 min to >102 pfu mL-1, yet progression to clinical disease is infrequent unless the challenge dose is >104 pfu mL-1. Asymptomatic infections were detected up to 39 d post-challenge. No virus was detected by tissue culture in natural Chinook juveniles cohabitated with experimentally IHNV-infected hatchery Chinook at ratios of 1:1, 1:10, and 1:20 for either 5 min or 24 h. Horizontal transmission of the Sacramento River strain of IHNV from infected juvenile hatchery fish to wild cohorts would appear to be a low ecological risk. The study results demonstrate key differences between IHNV infections as present in a hatchery and the natural environment. These differences should be considered during risk assessments of the impact of IHNV infections on wild salmon and
Full Text Available IntroductionSierra Leone experienced an unprecedented Ebola virus disease (EVD outbreak in all its districts. Koinadugu District was the last to report an EVD case. Several outbreak response strategies were implemented. As part of lessons learnt, we conducted an observational study to describe the transmission chain in the district and the impact of the control measures implemented to contain the outbreak.MethodsWe reconstructed the transmission chain, positioning both confirmed and probable cases, described the distribution of the EVD confirmed cases in the context of the routes of transmission (Community, Funeral or Health facility setting and assessed the impact of control measures using the surveillance data collected during the outbreak.ResultsAll 142 confirmed and probable EVD cases registered were fully resolved in the transmission chain. 72.5% of all the EVD cases in the district were exposed in the community, 26.1% exposed during funerals, and 1.4% exposed in the health facility setting. Health-care workers contributed little to the EVD outbreak. 71.1% of EVD transmission occurred among family members. Female EVD cases generated more secondary cases than their male counterparts (P = 0.03. With removal of EVD cases from the community and admission to the community care center (CCC, the EVD transmission in the community decreased to substantially lower rates. In addition, transmission due to exposure in health facilities was further reduced with the implementation of full infection and prevention controls.ConclusionThis study details the transmission chain of EVD in a rural district setting and the public health interventions implemented to successfully limit the outbreak to just one of 11 chiefdoms. Heightened community-based surveillance for early case detection, swift isolation of suspect cases, efficient contact tracing and monitoring, and good infection prevention and control measures in health facilities were highly effective in
Azwa, Iskandar; Khong, Su Yen
Mother-to-child transmission (MTCT) of human immunodefi ciency virus (HIV) is a devastating consequence of HIV infection during pregnancy and is largely preventable. Evidence-based interventions such as universal antenatal screening, provision of antiretroviral therapy, delivery by elective caesarean section and avoidance of breastfeeding have ensured that the rates of MTCT remain low in Malaysia. This review discusses the most recent advances in the management of HIV infection in pregnancy with emphasis on antiretroviral treatment strategies and obstetric care in a middle income country.
Hagberg, Emma Elisabeth; Pedersen, Anders Gorm; Larsen, Lars E
Aleutian mink disease virus (AMDV) is a frequently encountered pathogen associated with mink farming. Previous phylogenetic analyses of AMDV have been based on shorter and more conserved parts of the genome, e.g. the partial NS1 gene. Such fragments are suitable for detection but are less useful...... direction of spread. It was however impossible to infer transmission pathways from the partial NS1 gene tree, since all samples from the case farms branched out from a single internal node. A sliding window analysis showed that there were no shorter genomic regions providing the same phylogenetic resolution...
Nishimura, Yoshiaki; Goto, Yuko; Yoneda, Kumiko; Endo, Yasuyuki; Mizuno, Takuya; Hamachi, Masaharu; Maruyama, Hiroyuki; Kinoshita, Hirotoshi; Koga, Susumu; Komori, Mitsuru; Fushuku, Seigo; Ushinohama, Kanji; Akuzawa, Masao; Watari, Toshihiro; Hasegawa, Atsuhiko; Tsujimoto, Hajime
Feline immunodeficiency virus (FIV) was isolated from a wild-caught Tsushima cat (Felis bengalensis euptilura), an endangered Japanese nondomestic subspecies of leopard cat (F. bengalensis). Phylogenetic analysis of the env gene sequences indicated that the FIV from the Tsushima cat belonged to a cluster of subtype D FIVs from domestic cats. FIVs from both the Tsushima cat and the domestic cat showed similar levels of replication and cytopathicity in lymphoid cell lines derived from these two species. The results indicated the occurrence of interspecies transmission of FIV from the domestic cat to the Tsushima cat in the wild. PMID:10438892
Freuling, Conrad M; Binger, Tabea; Beer, Martin; Adu-Sarkodie, Yaw; Schatz, Juliane; Fischer, Melina; Hanke, Dennis; Hoffmann, Bernd; Höper, Dirk; Mettenleiter, Thomas C; Oppong, Samual K; Drosten, Christian; Müller, Thomas
A brain sample of a straw-coloured fruit bat (Eidolon helvum) from Ghana without evident signs of disease tested positive by generic Lyssavirus RT-PCR and direct antigen staining. Sequence analysis confirmed the presence of a Lagos bat virus belonging to phylogenetic lineage A. Virus neutralization tests using the isolate with sera from the same group of bats yielded neutralizing antibodies in 74% of 567 animals. No cross-neutralization was observed against a different Lagos bat virus (lineage B). Copyright © 2015 Elsevier B.V. All rights reserved.
Full Text Available On February 1, 2016, the World Health Organization declared that the cluster of microcephaly cases and other neurological disorders constitute public health emergency of international concern. Furthermore, few studies demonstrated that there was an increased evidence of causal relationship of Zika virus (ZIKAV infection and microcephaly, birth abnormalities and neurological disorders such as Guillain–Barré syndrome. ZIKAV transmission occurs mainly by the bite of infected mosquitos (Aedes species, but there are also reports that infections could occur via the placenta, breast milk, saliva, blood transfusion and sex. This article reviews the global efforts, progress in scientific research to understand the pathogenesis of ZIKAV infection & disease, clinical presentations, congenital transmission and autoimmune neurological disorders. The paper further explores the knowledge gaps, future priority research agenda for strategic response including vector control and prevention. We conducted a systematic literature review to synthesise available evidence on ZIKAV infection and its vector and host interaction from electronic databases.
Yitades Gebre; Nikkiah Forbes; Teshome Gebre
On February 1, 2016, the World Health Organization declared that the cluster of microcephaly cases and other neurological disorders constitute public health emergency of international concern. Furthermore, few studies demonstrated that there was an increased evidence of causal relationship of Zika virus(ZIKAV) infection and microcephaly, birth abnormalities and neurological disorders such as Guillain–Barre′ syndrome.ZIKAV transmission occurs mainly by the bite of infected mosquitos(Aedes species), but there are also reports that infections could occur via the placenta, breast milk, saliva,blood transfusion and sex. This article reviews the global efforts, progress in scientific research to understand the pathogenesis of ZIKAV infection & disease, clinical presentations, congenital transmission and autoimmune neurological disorders. The paper further explores the knowledge gaps, future priority research agenda for strategic response including vector control and prevention. We conducted a systematic literature review to synthesise available evidence on ZIKAV infection and its vector and host interaction from electronic databases.
Kevin A. Caillouët
Full Text Available Sensitive indicators of spatial and temporal variation in vector-host contact rates are critical to understanding the transmission and eventual prevention of arboviruses such as West Nile virus (WNV. Monitoring vector contact rates on particularly susceptible and perhaps more exposed avian nestlings may provide an advanced indication of local WNV amplification. To test this hypothesis we monitored WNV infection and vector contact rates among nestlings occupying nest boxes (primarily Eastern bluebirds; Sialia sialis, Turdidae across Henrico County, Virginia, USA, from May to August 2012. Observed host-seeking rates were temporally variable and associated with absolute vector and host abundances. Despite substantial effort to monitor WNV among nestlings and mosquitoes, we did not detect the presence of WNV in these populations. Generally low vector-nestling host contact rates combined with the negative WNV infection data suggest that monitoring transmission parameters among nestling Eastern bluebirds in Henrico County, Virginia, USA may not be a sensitive indicator of WNV activity.
Zhu, Yu; Liang, Lin; Luo, Yakun; Wang, Guihua; Wang, Chunren; Cui, Yudong; Ai, Xia; Cui, Shangjin
In this study, a novel duplex nanoparticle-assisted polymerase chain reaction (nanoPCR) assay was developed to detect porcine epidemic diarrhea virus (PEDV) and porcine transmissible gastroenteritis virus (TGEV). Two pairs of primers were designed based on the conserved region within the N gene of PEDV and TGEV. In a screening of 114 clinical samples from four provinces in China for PEDV and TGEV, 48.2 and 3.5 % of the samples, respectively, tested positive. Under optimized conditions, the duplex nanoPCR assay had a detection limit of 7.6 × 10 1 and 8.5 × 10 1 copies μL -1 for PEDV and TGEV, respectively. The sensitivity of the duplex nanoPCR assay was ten times higher than that of a conventional PCR assay. Moreover, no fragments were amplified when the duplex nanoPCR assay was used to test samples containing other porcine viruses. Our results indicate that the duplex nanoPCR assay described here is useful for the rapid detection of PEDV and TGEV and can be applied in clinical diagnosis.
Li, Hui; Stoddard, Mark B; Wang, Shuyi; Giorgi, Elena E; Blair, Lily M; Learn, Gerald H; Hahn, Beatrice H; Alter, Harvey J; Busch, Michael P; Fierer, Daniel S; Ribeiro, Ruy M; Perelson, Alan S; Bhattacharya, Tanmoy; Shaw, George M
Despite the recent development of highly effective anti-hepatitis C virus (HCV) drugs, the global burden of this pathogen remains immense. Control or eradication of HCV will likely require the broad application of antiviral drugs and development of an effective vaccine. A precise molecular identification of transmitted/founder (T/F) HCV genomes that lead to productive clinical infection could play a critical role in vaccine research, as it has for HIV-1. However, the replication schema of these two RNA viruses differ substantially, as do viral responses to innate and adaptive host defenses. These differences raise questions as to the certainty of T/F HCV genome inferences, particularly in cases where multiple closely related sequence lineages have been observed. To clarify these issues and distinguish between competing models of early HCV diversification, we examined seven cases of acute HCV infection in humans and chimpanzees, including three examples of virus transmission between linked donors and recipients. Using single-genome sequencing (SGS) of plasma vRNA, we found that inferred T/F sequences in recipients were identical to viral sequences in their respective donors. Early in infection, HCV genomes generally evolved according to a simple model of random evolution where the coalescent corresponded to the T/F sequence. Closely related sequence lineages could be explained by high multiplicity infection from a donor whose viral sequences had undergone a pretransmission bottleneck due to treatment, immune selection, or recent infection. These findings validate SGS, together with mathematical modeling and phylogenetic analysis, as a novel strategy to infer T/F HCV genome sequences. Despite the recent development of highly effective, interferon-sparing anti-hepatitis C virus (HCV) drugs, the global burden of this pathogen remains immense. Control or eradication of HCV will likely require the broad application of antiviral drugs and the development of an effective
Full Text Available An indexing of the organs (radicle and plumule and components (husk, endosperm and embryo of rice seeds using Enzyme Linked Immunosorbent Assay (ELISA was carried out to detect Rice yellow mottle virus (RYMV and establish the exact location of the virus in the rice seed. RYMV was detected only in the husk (seed coat but not in the endosperm, plumule, radicle, nor embryo. None of the seedlings raised from the seeds expressed RYMV symptoms. No virus particle was detected by the ELISA test in the leaves of the screenhouse-reared plants obtained from seeds of infected plants. The results indicate that RYMV is apparently not transmitted through rice seed probably because the virus is seed-borne in the husk (seed coat of mature rice seeds.
Full Text Available Background & Objective: The immune system of Patients with Acquired Immune Deficiency Syndrome (AIDS is weekend because of Human immunodeficiency virus (HIV infection, and they become vulnerable to several opportunistic and non-opportunistic pathogens and different carcinomas. IV drug abuse, sexual contact, occupational transmission, blood transfusion and maternal-fetal transmission are well known transmission routes for HIV infection. This study was under taken to investigate the prevalence of HIV transmission routs in the HIV infected population of Sirjan, and their knowledge about the disease, in order to plan better preventive strategies. Materials & Methods: A cross sectional study was planned. During a 6-month period in 2010, all of the HIV infected people in Sirjan (old and new cases who had a file at the consultation center for high risk behavior, completed a valid and reliable questionnaire. Results: The definite route of transmission was not clear in any of the patients because they had more than one suspicious route. Injected drug abusers were the most common (88.4% followed by those who got tattoos (79.1%, invasive therapeutic procedures, dentistry, surgery and endoscopy (56.1%, high risk sexual behavior (62.8%, bloodletting (9.3%, injuries in the barbershop (9.3% and blood transfusion (2.3%. Conclusion: All of the HIV infected cases in Sirjan were involved with several high risk behaviors, but the major route of transmission, similar to other parts of the country was injected drug abuse. Educational programs for prevention of AIDS should be followed seriously and special attention should be paid to groups with multiple high risk behaviors.
WEEV in Ontario, Canada in 194126. This virus has a passage history including both animals and cell culture. Biosafety level (BSL-)-3 laboratory...Agarose-Based Plaque Assay Each virus stock was quantitated by standard agarose-based plaque assay23...samples used here were well prepared and the standard macro was used. As we have developed this method we have observed that while inferior
Rojas, DP; Dean, NE; Yang, Y; Kenah, E; Quintero, J; Tomasi, S; Ramirez, EL; Kelly, Y; Castro, C; Carrasquilla, G; Halloran, ME; Longini, IM
Transmission of Zika virus (ZIKV) was first detected in Colombia in September 2015. As of April 2016, Colombia had reported over 65,000 cases of Zika virus disease (ZVD). We analysed daily surveillance data of ZVD cases reported to the health authorities of San Andres and Girardot, Colombia, between September 2015 and January 2016. ZVD was laboratory-confirmed by reverse transcription-polymerase chain reaction (RT-PCR) in the serum of acute cases within five days of symptom onset. We use daily incidence data to estimate the basic reproductive number (R0) in each population. We identified 928 and 1,936 reported ZVD cases from San Andres and Girardot, respectively. The overall attack rate for reported ZVD was 12.13 cases per 1,000 residents of San Andres and 18.43 cases per 1,000 residents of Girardot. Attack rates were significantly higher in females in both municipalities (p < 0.001). Cases occurred in all age groups with highest rates in 20 to 49 year-olds. The estimated R0 for the Zika outbreak was 1.41 (95% confidence interval (CI): 1.15–1.74) in San Andres and 4.61 (95% CI: 4.11–5.16) in Girardot. Transmission of ZIKV is ongoing in the Americas. The estimated R0 from Colombia supports the observed rapid spread. PMID:27452806
Edwards, Michael C; Weiland, John J; Todd, Jane; Stewart, Lucy R; Lu, Shunwen
Maize rayado fino virus (MRFV) possesses an open reading frame (ORF43) predicted to encode a 43 kDa protein (p43) that has been postulated to be a viral movement protein. Using a clone of MRFV (pMRFV-US) from which infectious RNA can be produced, point mutations were introduced to either prevent initiation from three potential AUG initiation codons near the 5'-end of ORF43 or prematurely terminate translation of ORF43. Inoculation of maize seed via vascular puncture inoculation (VPI) resulted in plants exhibiting symptoms typical of MRFV infection for all mutants tested. Furthermore, corn leafhoppers (Dalbulus maidis) transmitted the virus mutants to healthy plants at a frequency similar to that for wild-type MRFV-US. Viral RNA recovered from plants infected with mutants both prior to and after leafhopper transmission retained mutations blocking ORF43 expression. The results indicate that ORF43 of MRFV is dispensable for both systemic infection of maize and transmission by leafhoppers.
Morin, Cory; Monaghan, Andrew; Quattrochi, Dale; Crosson, William; Hayden, Mary; Ernst, Kacey
Dengue fever is a mosquito-borne viral disease reemerging throughout much of the tropical Americas. Dengue virus transmission is explicitly influenced by climate and the environment through its primary vector, Aedes aegypti. Temperature regulates Ae. aegypti development, survival, and replication rates as well as the incubation period of the virus within the mosquito. Precipitation provides water for many of the preferred breeding habitats of the mosquito, including buckets, old tires, and other places water can collect. Although transmission regularly occurs along the border region in Mexico, dengue virus transmission in bordering Arizona has not occurred. Using NASA's TRMM (Tropical Rainfall Measuring Mission) satellite for precipitation input and Daymet for temperature and supplemental precipitation input, we modeled dengue transmission along a US-Mexico transect using a dynamic dengue transmission model that includes interacting vector ecology and epidemiological components. Model runs were performed for 5 cities in Sonora, Mexico and southern Arizona. Employing a Monte Carlo approach, we performed ensembles of several thousands of model simulations in order to resolve the model uncertainty arising from using different combinations of parameter values that are not well known. For cities with reported dengue case data, the top model simulations that best reproduced dengue case numbers were retained and their parameter values were extracted for comparison. These parameter values were used to run simulations in areas where dengue virus transmission does not occur or where dengue fever case data was unavailable. Additional model runs were performed to reveal how changes in climate or parameter values could alter transmission risk along the transect. The relative influence of climate variability and model parameters on dengue virus transmission is assessed to help public health workers prepare location specific infection prevention strategies.
Raina K Plowright
Full Text Available Progress in combatting zoonoses that emerge from wildlife is often constrained by limited knowledge of the biology of pathogens within reservoir hosts. We focus on the host-pathogen dynamics of four emerging viruses associated with bats: Hendra, Nipah, Ebola, and Marburg viruses. Spillover of bat infections to humans and domestic animals often coincides with pulses of viral excretion within bat populations, but the mechanisms driving such pulses are unclear. Three hypotheses dominate current research on these emerging bat infections. First, pulses of viral excretion could reflect seasonal epidemic cycles driven by natural variations in population densities and contact rates among hosts. If lifelong immunity follows recovery, viruses may disappear locally but persist globally through migration; in either case, new outbreaks occur once births replenish the susceptible pool. Second, epidemic cycles could be the result of waning immunity within bats, allowing local circulation of viruses through oscillating herd immunity. Third, pulses could be generated by episodic shedding from persistently infected bats through a combination of physiological and ecological factors. The three scenarios can yield similar patterns in epidemiological surveys, but strategies to predict or manage spillover risk resulting from each scenario will be different. We outline an agenda for research on viruses emerging from bats that would allow for differentiation among the scenarios and inform development of evidence-based interventions to limit threats to human and animal health. These concepts and methods are applicable to a wide range of pathogens that affect humans, domestic animals, and wildlife.
Sether, D M; Ullman, D E; Hu, J S
ABSTRACT Closterovirus-like particles associated with mealybug wilt of pineapple were acquired and transmitted by the pink pineapple mealybug, Dysmicoccus brevipes, and the gray pineapple mealybug, D. neobrevipes. Mealybugs acquired pineapple mealybug wilt-associated virus (PMWaV) from infected pineapple plants or detached leaves. The virus was detected in plants by tissue blot immunoassay and confirmed by immunosorbent electron microscopy. Plants exposed to mealybugs reared on PMWaV-free pineapple tissue remained uninfected. The presence of ants was correlated with an increased rate of virus spread when caged with D. brevipes. All stages of D. neobrevipes acquired PMWaV, although vector efficiency decreased significantly in older adult females. The probability of a single third-instar immature transmitting the virus was 0.04. Both species of mealybug acquired and transmitted PMWaV from infected pineapple material that had been clonally propagated for decades, and both species acquired PMWaV from sources previously infected with the virus by the other mealybug species.
Paintsil, Elijah; Binka, Mawuena; Patel, Amisha; Lindenbach, Brett D; Heimer, Robert
Healthcare workers may come into contact with fomites that contain infectious hepatitis C virus (HCV) during preparation of plasma or following placement or removal of venous lines. Similarly, injection drugs users may come into contact with fomites. Hypothesizing that prolonged viability of HCV in fomites may contribute significantly to incidence, we determined the longevity of virus infectivity and the effectiveness of antiseptics. We determined the volume of drops misplaced during transfer of serum or plasma. Aliquots equivalent to the maximum drop volume of plasma spiked with the 2a HCV reporter virus were loaded into 24-well plates. Plates were stored uncovered at 3 temperatures: 4°C, 22°C, and 37°C for up to 6 weeks before viral infectivity was determined in a microculture assay. The mean volume of an accidental drop was 29 µL (min-max of 20-33 µL). At storage temperatures 4°C and 22°C, we recovered viable HCV from the low-titer spots for up to 6 weeks of storage. The rank order of HCV virucidal activity of commonly used antiseptics was bleach (1:10) > cavicide (1:10) > ethanol (70%). The hypothesis of potential transmission from fomites was supported by the experimental results. The anti-HCV activity of commercial antiseptics varied.
Benjamin M Althouse
Full Text Available Isolations of sylvatic dengue-2 virus from mosquitoes, humans and non-human primates in Senegal show synchronized multi-annual dynamics over the past 50 years. Host demography has been shown to directly affect the period between epidemics in other pathogen systems, therefore, one might expect unsynchronized multi-annual cycles occurring in hosts with dramatically different birth rates and life spans. However, in Senegal, we observe a single synchronized eight-year cycle across all vector species, suggesting synchronized dynamics in all vertebrate hosts. In the current study, we aim to explore two specific hypotheses: 1 primates with different demographics will experience outbreaks of dengue at different periodicities when observed as isolated systems, and that coupling of these subsystems through mosquito biting will act to synchronize incidence; and 2 the eight-year periodicity of isolations observed across multiple primate species is the result of long-term cycling in population immunity in the host populations. To test these hypotheses, we develop a multi-host, multi-vector Susceptible, Infected, Removed (SIR model to explore the effects of coupling multiple host-vector systems of dengue virus transmission through cross-species biting rates. We find that under small amounts of coupling, incidence in the host species synchronize. Long-period multi-annual dynamics are observed only when prevalence in troughs reaches vanishingly small levels (< 10(-10, suggesting that these dynamics are inconsistent with sustained transmission in this setting, but are consistent with local dengue virus extinctions followed by reintroductions. Inclusion of a constant introduction of infectious individuals into the system causes the multi-annual periods to shrink, while the effects of coupling remain the same. Inclusion of a stochastic rate of introduction allows for multi-annual periods at a cost of reduced synchrony. Thus, we conclude that the eight-year period
Liu, Baoyuan; Sun, Yani; Chen, Yiyang; Du, Taofeng; Nan, Yuchen; Wang, Xinjie; Li, Huixia; Huang, Baicheng; Zhang, Gaiping; Zhou, En-Min; Zhao, Qin
Avian hepatitis E virus (HEV) infection is common in chicken flocks in China, as currently no measures exist to prevent the spread of the disease. In this study, we analyzed the effect of caged versus cage-free housing arrangements on avian HEV transmission. First, 127 serum and 110 clinical fecal samples were collected from 4 chicken flocks including the two arrangements in Shaanxi Province, China and tested for HEV antibodies and/or virus. Concurrently, 36 specific-pathogen-free chickens were divided equally into four experimental living arrangement groups, designated cage-free (Inoculated), caged (Inoculated), cage-free (Negative) and caged (Negative) groups. In caged groups, three cages contained 3 chickens each. Three chickens each from cage-free (Inoculated) and caged (Inoculated) groups (one chicken of each cage) were inoculated by cutaneous ulnar vein with the same dose of avian HEV, respectively. The cage-free (Negative) and caged (Negative) groups served as negative control. Serum and fecal samples were collected at 1 to 7 weeks post-inoculation (wpi) and liver lesions were scored at 7 wpi. The results of serology showed that the avian HEV infection rate (54.10%) of the cage-free chickens was significantly higher than the one (12.12%) for caged chickens (P chickens (6) was significantly higher than the one for the uninoculated caged birds (2), as evidenced by seroconversion, fecal virus shedding, viremia and gross and microscopic liver lesions. These results suggest that reduction of contact with feces as seen in the caged arrangement of housing chickens can reduce avian HEV transmission. This study provides insights for prevention and control of avian HEV infection in chicken flocks.
Chan, Jasper Fuk-Woo; To, Kelvin Kai-Wang; Chen, Honglin; Yuen, Kwok-Yung
Birds, the only living member of the Dinosauria clade, are flying warm-blooded vertebrates displaying high species biodiversity, roosting and migratory behavior, and a unique adaptive immune system. Birds provide the natural reservoir for numerous viral species and therefore gene source for evolution, emergence and dissemination of novel viruses. The intrusions of human into natural habitats of wild birds, the domestication of wild birds as pets or racing birds, and the increasing poultry consumption by human have facilitated avian viruses to cross species barriers to cause zoonosis. Recently, a novel adenovirus was exclusively found in birds causing an outbreak of Chlamydophila psittaci infection among birds and humans. Instead of being the primary cause of an outbreak by jumping directly from bird to human, a novel avian virus can be an augmenter of another zoonotic agent causing the outbreak. A comprehensive avian virome will improve our understanding of birds' evolutionary dynamics. Copyright © 2015 Elsevier B.V. All rights reserved.
Wang, Zeng; Yang, Huanliang; Chen, Yan; Tao, Shiyu; Liu, Liling; Kong, Huihui; Ma, Shujie; Meng, Fei; Suzuki, Yasuo; Qiao, Chuanling; Chen, Hualan
Efficient transmission from human to human is the prerequisite for an influenza virus to cause a pandemic; however, the molecular determinants of influenza virus transmission are still largely unknown. In this study, we explored the molecular basis for transmission of Eurasian avian-like H1N1 (EAH1N1) swine influenza viruses by comparing two viruses that are genetically similar but differ in their transmissibility in guinea pigs: the A/swine/Guangxi/18/2011 virus (GX/18) is highly transmissible by respiratory droplet in guinea pigs, whereas the A/swine/Heilongjiang/27/2012 virus (HLJ/27) does not transmit in this animal model. We used reverse genetics to generate a series of reassortants and mutants in the GX/18 background and tested their transmissibility in guinea pigs. We found that a single-amino-acid substitution of glycine (G) for glutamic acid (E) at position 225 (E225G) in the HA1 protein completely abolished the respiratory droplet transmission of GX/18, whereas the substitution of E for G at the same position (G225E) in HA1 enabled HLJ/27 to transmit in guinea pigs. We investigated the underlying mechanism and found that viruses bearing 225E in HA1 replicated more rapidly than viruses bearing 225G due to differences in assembly and budding efficiencies. Our study indicates that the amino acid 225E in HA1 plays a key role in EAH1N1 swine influenza virus transmission and provides important information for evaluating the pandemic potential of field influenza virus strains. IMPORTANCE Efficient transmission among humans is a prerequisite for a novel influenza virus to cause a human pandemic. Transmissibility of influenza viruses is a polygenic trait, and understanding the genetic determinants for transmissibility will provide useful insights for evaluating the pandemic potential of influenza viruses in the field. Several amino acids in the hemagglutinin (HA) protein of influenza viruses have been shown to be important for transmissibility, usually by
Elderfield, Ruth A.; Koutsakos, Marios; Frise, Rebecca; Bradley, Konrad; Ashcroft, Jonathan; Miah, Shanhjahan; Lackenby, Angie
The influenza B virus encodes a unique protein, NB, a membrane protein whose function in the replication cycle is not, as yet, understood. We engineered a recombinant influenza B virus lacking NB expression, with no concomitant difference in expression or activity of viral neuraminidase (NA) protein, an important caveat since NA is encoded on the same segment and initiated from a start codon just 4 nt downstream of NB. Replication of the virus lacking NB was not different to wild-type virus with full-length NB in clonal immortalized or complex primary cell cultures. In the mouse model, virus lacking NB induced slightly lower IFN-α levels in infected lungs, but this did not affect virus titres or weight loss. In ferrets infected with a mixture of viruses that did or did not express NB, there was no fitness advantage for the virus that retained NB. Moreover, virus lacking NB protein was transmitted following respiratory droplet exposure of sentinel animals. These data suggest no role for NB in supporting replication or transmission in vivo in this animal model. The role of NB and the nature of selection to retain it in all natural influenza B viruses remain unclear. PMID:26703440
Sun, Jiufeng; Wu, De; Zhong, Haojie; Guan, Dawei; Zhang, Huan; Tan, Qiqi; Zhou, Huiqiong; Zhang, Meng; Ning, Dan; Zhang, Baohuan; Ke, Changwen; Song, Tie; Lin, Jinyan; Zhang, Yonghui; Koopmans, Marion; Gao, George F
Fast expansion and linkage to microcephaly and Guillain Barre syndrome have made Zika virus (ZIKV) track attention of global health authority concerns. The epidemiology, virological characteristics and genetic evolution of introduced ZIKV to Guangdong, China, were investigated. Analyses of the epidemiological characteristics and genetic diversity of ZIKV isolates were performed. A total of twenty-eight confirmed ZIKV infection cases were imported into China in 2016, of which 19 were imported into Guangdong, China from Venezuela (16), the Samoa Islands (1), Suriname (1) and Guatemala (1). Serial sampling studies of the cases indicated longer shedding times of ZIKV particles from urine and saliva samples than from serum and conjunctiva swab samples. Seven ZIKV strains were successfully isolated from serum, urine and conjunctiva swab samples using cell culture and neonatal mouse injection methods. Genomic analysis indicated that all viruses belonged to the Asian lineage but had different evolutionary transmission routes with different geographic origins. The molecular clock phylogenetic analysis of the ZIKV genomes indicated independent local transmission that appeared to have been previously established in Venezuela and Samoa. Additionally, we found 7 unique non-synonymous mutations in the genomes of ZIKV that were imported to China. The mutations may indicate that ZIKV has undergone independent evolutionary history not caused by sudden adaptation to Chinese hosts. The increasing number of ex-patriot Chinese returning fr