RESUMEN
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exhibits strong stability on conventional stainless steel (SS) surface, with infectious virus detected even after two days, posing a high risk of virus transmission via surface touching in public areas. In order to mitigate the surface toughing transmission, the present study develops the first SS with excellent anti-pathogen properties against SARS-COV-2. The stabilities of SARS-CoV-2, H1N1 influenza A virus (H1N1), and Escherichia coli (E.coli) on the surfaces of Cu-contained SS, pure Cu, Ag-contained SS, and pure Ag were investigated. It is discovered that pure Ag and Ag-contained SS surfaces do not display apparent inhibitory effects on SARS-CoV-2 and H1N1. In comparison, both pure Cu and Cu-contained SS with a high Cu content exhibit significant antiviral properties. Significantly, the developed anti-pathogen SS with 20 wt% Cu can distinctly reduce 99.75% and 99.99% of viable SARS-CoV-2 on its surface within 3 and 6 h, respectively. In addition, the present anti-pathogen SS also exhibits an excellent inactivation ability for H1N1 influenza A virus (H1N1), and Escherichia coli (E.coli). Interestingly, the Cu ion concentration released from the anti-pathogen SS with 10 wt% and 20 wt% Cu was notably higher than the Ag ion concentration released from Ag and the Ag-contained SS. Lift buttons made of the present anti-pathogen SS are produced using mature powder metallurgy technique, demonstrating its potential applications in public areas and fighting the transmission of SARS-CoV-2 and other pathogens via surface touching.
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Linfocitos T CD4-Positivos/efectos de los fármacos , Linfocitos T CD8-positivos/efectos de los fármacos , Vacunas contra la Influenza/farmacología , Gripe Humana/prevención & control , Orthomyxoviridae/inmunología , Animales , Citoprotección , Femenino , Humanos , Subtipo H1N1 del Virus de la Influenza A/inmunología , Subtipo H3N2 del Virus de la Influenza A/inmunología , Subtipo H7N7 del Virus de la Influenza A/inmunología , Subtipo H7N9 del Virus de la Influenza A/inmunología , Gripe Humana/inmunología , Ratones , Ratones Endogámicos BALB CRESUMEN
Equine coronaviruses (ECoV) are the only coronavirus known to infect horses. So far, data on ECoV infection in horses remain limited to the USA, France and Japan and its geographic distribution is not well understood. We carried out RT-PCR on 306 nasal and 315 rectal swabs and tested 243 sera for antibodies to detect coronavirus infections in apparently healthy horses in Saudi Arabia and Oman. We document evidence of infection with ECoV and HKU23 coronavirus by RT-PCR. There was no conclusive evidence of Middle East respiratory syndrome coronavirus infection in horses. Serological data suggest that lineage A betacoronavirus infections are commonly infecting horses in Saudi Arabia and Oman but antibody cross-reactivities between these viruses do not permit us to use serological data alone to identify which coronaviruses are causing these infections.
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Betacoronavirus/inmunología , Infecciones por Coronavirus/veterinaria , Coronavirus/inmunología , Enfermedades de los Caballos/epidemiología , Coronavirus del Síndrome Respiratorio de Oriente Medio/inmunología , Animales , Betacoronavirus/genética , Betacoronavirus/aislamiento & purificación , Chlorocebus aethiops , Coronavirus/genética , Coronavirus/aislamiento & purificación , Infecciones por Coronavirus/epidemiología , Infecciones por Coronavirus/virología , Reacciones Cruzadas , Enfermedades de los Caballos/virología , Caballos , Coronavirus del Síndrome Respiratorio de Oriente Medio/genética , Coronavirus del Síndrome Respiratorio de Oriente Medio/aislamiento & purificación , Omán/epidemiología , Arabia Saudita/epidemiología , Células VeroRESUMEN
The emergence of the H7N9 influenza virus in humans in Eastern China has raised concerns that a new influenza pandemic could occur. Here, we used a ferret model to evaluate the infectivity and transmissibility of A/Shanghai/2/2013 (SH2), a human H7N9 virus isolate. This virus replicated in the upper and lower respiratory tracts of the ferrets and was shed at high titers for 6 to 7 days, with ferrets showing relatively mild clinical signs. SH2 was efficiently transmitted between ferrets via direct contact, but less efficiently by airborne exposure. Pigs were productively infected by SH2 and shed virus for 6 days but were unable to transmit the virus to naïve pigs or ferrets. Under appropriate conditions, human-to-human transmission of the H7N9 virus may be possible.
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Enfermedades Transmisibles Emergentes/transmisión , Enfermedades Transmisibles Emergentes/virología , Gripe Humana/transmisión , Gripe Humana/virología , Orthomyxoviridae/patogenicidad , Animales , Modelos Animales de Enfermedad , Hurones , Humanos , Gripe Humana/patología , Orthomyxoviridae/clasificación , Orthomyxoviridae/genética , Sistema Respiratorio/patología , Sistema Respiratorio/virología , Sus scrofaRESUMEN
Data on analytical sensitivity of rapid diagnostic assays are important for clinical management of influenza, especially during a pandemic. Four rapid antigen detection assays were compared for detection of pandemic influenza A H1N1 2009, seasonal H1N1 and H3N2 in 96 patients with influenza A infection confirmed by real-time RT-PCR. These rapid antigen tests appeared to have lower sensitivity (55.8%) for the diagnosis of pandemic influenza A H1N1 2009 as compared with seasonal H3N2 (71.0%) or H1N1 (69.4%) influenza infections, a difference that was related to a lower viral load in patients infected with the pandemic influenza A H1N1 2009 virus. The detection limit of these antigen detection tests in clinical specimens was an influenza A M gene copy number of average 1.0×10(7) copies/ml. Significant variations between tests in sensitivity for detection of pandemic influenza A H1N1 2009 (43.4-63.3%) were observed. The Directigen EZ Influenza A+B and the Espline Influenza A+B had comparable sensitivity (63%) and were the most sensitive among the four assays evaluated.
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Antígenos Virales/análisis , Técnicas de Laboratorio Clínico/métodos , Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H3N2 del Virus de la Influenza A/aislamiento & purificación , Gripe Humana/virología , Nasofaringe/virología , Virología/métodos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Humanos , Inmunoensayo/métodos , Lactante , Masculino , Persona de Mediana Edad , Sensibilidad y Especificidad , Adulto JovenAsunto(s)
Gripe Humana/epidemiología , Gripe Humana/virología , Ganado/virología , Infecciones por Orthomyxoviridae/veterinaria , Orthomyxoviridae/patogenicidad , Pandemias/prevención & control , Vigilancia de la Población , Animales , Humanos , Gripe Aviar/epidemiología , Gripe Aviar/transmisión , Gripe Aviar/virología , Gripe Humana/transmisión , Orthomyxoviridae/genética , Orthomyxoviridae/aislamiento & purificación , Infecciones por Orthomyxoviridae/epidemiología , Infecciones por Orthomyxoviridae/transmisión , Infecciones por Orthomyxoviridae/virología , Aves de Corral , Virus Reordenados/genética , Virus Reordenados/patogenicidad , ZoonosisRESUMEN
The main route of transmission of SARS CoV infection is presumed to be respiratory droplets. However the virus is also detectable in other body fluids and excreta. The stability of the virus at different temperatures and relative humidity on smooth surfaces were studied. The dried virus on smooth surfaces retained its viability for over 5 days at temperatures of 22-25°C and relative humidity of 40-50%, that is, typical air-conditioned environments. However, virus viability was rapidly lost (>3 log(10)) at higher temperatures and higher relative humidity (e.g., 38°C, and relative humidity of >95%). The better stability of SARS coronavirus at low temperature and low humidity environment may facilitate its transmission in community in subtropical area (such as Hong Kong) during the spring and in air-conditioned environments. It may also explain why some Asian countries in tropical area (such as Malaysia, Indonesia or Thailand) with high temperature and high relative humidity environment did not have major community outbreaks of SARS.
RESUMEN
The emergence of pandemic H1N1/2009 influenza demonstrated that pandemic viruses could be generated in swine. Subsequent reintroduction of H1N1/2009 to swine has occurred in multiple countries. Through systematic surveillance of influenza viruses in swine from a Hong Kong abattoir, we characterize a reassortant progeny of H1N1/2009 with swine viruses. Swine experimentally infected with this reassortant developed mild illness and transmitted infection to contact animals. Continued reassortment of H1N1/2009 with swine influenza viruses could produce variants with transmissibility and altered virulence for humans. Global systematic surveillance of influenza viruses in swine is warranted.
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Subtipo H1N1 del Virus de la Influenza A/genética , Infecciones por Orthomyxoviridae/veterinaria , Virus Reordenados/genética , Enfermedades de los Porcinos/virología , Porcinos/virología , Mataderos , Animales , Brotes de Enfermedades , Genes Virales , Genotipo , Glicoproteínas Hemaglutininas del Virus de la Influenza/genética , Hong Kong , Humanos , Subtipo H1N1 del Virus de la Influenza A/clasificación , Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H1N1 del Virus de la Influenza A/patogenicidad , Subtipo H1N2 del Virus de la Influenza A/clasificación , Subtipo H1N2 del Virus de la Influenza A/genética , Subtipo H1N2 del Virus de la Influenza A/aislamiento & purificación , Gripe Humana/epidemiología , Gripe Humana/virología , Datos de Secuencia Molecular , Neuraminidasa/genética , Infecciones por Orthomyxoviridae/epidemiología , Infecciones por Orthomyxoviridae/transmisión , Infecciones por Orthomyxoviridae/virología , Filogenia , Vigilancia de la Población , Virus Reordenados/clasificación , Virus Reordenados/aislamiento & purificación , Enfermedades de los Porcinos/epidemiología , Enfermedades de los Porcinos/transmisiónRESUMEN
BACKGROUND: A novel swine origin influenza virus (S-OIV) (H1N1) is spreading worldwide and threatens to become pandemic. OBJECTIVES: Determine analytical sensitivity of selected commercially available rapid influenza antigen detection tests in detecting S-OIV H1N1. STUDY DESIGN: Serial dilutions of two S-OIV isolates, one seasonal influenza A (H1N1) isolate and a nasopharyngeal aspirate from a patient with S-OIV disease were tested in five commercially available influenza antigen detection tests and by virus isolation in cell culture. Viral M gene copy number was determined by quantitative PCR methods. RESULTS: The analytical sensitivity of the five influenza antigen detection tests for S-OIV (tissue culture infectious dose 50 (TCID(50)) log(10)3.3-4.7 was comparable with that of seasonal influenza (TCID(50) log(10)4.0-4.5). CONCLUSION: The analytical sensitivity of the selected influenza A antigen detection tests for detection of S-IOV was comparable with that of seasonal influenza H1N1.
Asunto(s)
Antígenos Virales/análisis , Subtipo H1N1 del Virus de la Influenza A/aislamiento & purificación , Gripe Humana/diagnóstico , Gripe Humana/virología , Virus Reordenados/aislamiento & purificación , Animales , Antígenos Virales/inmunología , Humanos , Inmunoensayo/métodos , Subtipo H1N1 del Virus de la Influenza A/inmunología , Juego de Reactivos para Diagnóstico , Virus Reordenados/inmunología , Sensibilidad y Especificidad , PorcinosRESUMEN
Since it was first detected in 1996, the Goose/Guangdong/1/1996 (Gs/GD) H5N1 influenza virus and its reassortants have spread to over 60 countries, with over 20 distinct genetic reassortants previously recognized. However, systematic analysis of their interrelationship and the development of genetic diversity have not been explored. As each of those reassortants was first detected in China, here 318 full-length H5N1 virus genomes isolated from 1996 to 2006 in this region were phylogenetically analyzed. Our findings revealed two major group reassortment events in 2001 and 2002 that were responsible for the generation of the majority of the 44 distinct Gs/GD genotypes identified, excepting those 1997 variants. Genotype replacement and emergence occurred continually, with 34 transient genotypes detected while only 10 variants were persistent. Two major replacements of predominant genotypes were also observed: genotype B replaced by Z in 2002 and then genotype Z replaced by the now predominant genotype V in 2005.
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Evolución Molecular , Variación Genética , Subtipo H5N1 del Virus de la Influenza A/clasificación , Subtipo H5N1 del Virus de la Influenza A/genética , China , Genoma Viral , Genotipo , Subtipo H5N1 del Virus de la Influenza A/aislamiento & purificación , Datos de Secuencia Molecular , Filogenia , ARN Viral/genética , Virus Reordenados/clasificación , Virus Reordenados/genética , Virus Reordenados/aislamiento & purificación , Análisis de Secuencia de ADN , Homología de SecuenciaRESUMEN
Bats are increasingly recognized to harbor a wide range of viruses, and in most instances these viruses appear to establish long-term persistence in these animals. They are the reservoir of a number of human zoonotic diseases including Nipah, Ebola, and severe acute respiratory syndrome. We report the identification of novel groups of astroviruses in apparently healthy insectivorous bats found in Hong Kong, in particular, bats belonging to the genera Miniopterus and Myotis. Astroviruses are important causes of diarrhea in many animal species, including humans. Many of the bat astroviruses form distinct phylogenetic clusters in the genus Mamastrovirus within the family Astroviridae. Virus detection rates of 36% to 100% and 50% to 70% were found in Miniopterus magnater and Miniopterus pusillus bats, respectively, captured within a single bat habitat during four consecutive visits spanning 1 year. There was high genetic diversity of viruses in bats found within this single habitat. Some bat astroviruses may be phylogenetically related to human astroviruses, and further studies with a wider range of bat species in different geographic locations are warranted. These findings are likely to provide new insights into the ecology and evolution of astroviruses and reinforce the role of bats as a reservoir of viruses with potential to pose a zoonotic threat to human health.
Asunto(s)
Infecciones por Astroviridae/veterinaria , Astroviridae/clasificación , Quirópteros/virología , Variación Genética , Animales , Astroviridae/genética , Astroviridae/aislamiento & purificación , Infecciones por Astroviridae/virología , Quirópteros/clasificación , Clonación Molecular , Hong Kong , Humanos , Mamastrovirus/clasificación , Mamastrovirus/genética , Mamastrovirus/aislamiento & purificación , Datos de Secuencia Molecular , Filogenia , Análisis de Secuencia de ADN , Zoonosis/transmisión , Zoonosis/virologíaRESUMEN
We previously reported the detection of bat coronaviruses (bat CoVs 1A, 1B, HKU7, HKU8 and bat-severe acute respiratory syndrome coronavirus) in Miniopterus spp. that cohabit a cave in Hong Kong. Here, we report the full genomic sequences of bat CoVs 1A, 1B and HKU8. Bat CoVs 1A and 1B, which are commonly found in the Miniopterus, are phylogenetically closely related. Using species-specific RT-PCR assays, bat CoVs 1A and 1B were confirmed to have distinct host specificities to Miniopterus magnater and Miniopterus pusillus, respectively. Interestingly, co-infections of bat CoVs 1B and HKU8 in M. pusillus are detected in seven of 38 virus-positive specimens collected from 2004 to 2006. These findings highlight that co-infections of some coronaviruses might be common events in nature. The biological basis for the host restriction of bat coronaviruses, however, is yet to be determined.
Asunto(s)
Quirópteros/virología , Infecciones por Coronavirus/veterinaria , Coronavirus/genética , Genoma Viral , Animales , Coronavirus/aislamiento & purificación , Infecciones por Coronavirus/virología , Hong Kong , Datos de Secuencia Molecular , Filogenia , Análisis de Secuencia de ADN , Homología de SecuenciaRESUMEN
An H6N1 virus, A/teal/Hong Kong/W312/97 (W312), was isolated during the "bird flu" incident in Hong Kong in 1997. Genetic analysis suggested that this virus might be the progenitor of the A/Hong Kong/156/97 (HK/97) H5N1 virus, as seven of eight gene segments of those viruses had a common source. Continuing surveillance in Hong Kong showed that a W312-like virus was prevalent in quail and pheasants in 1999; however, the further development of H6N1 viruses has not been investigated since 2001. Here we report influenza virus surveillance data collected in southern China from 2000 to 2005 that show that H6N1 viruses have become established and endemic in minor poultry species and replicate mainly in the respiratory tract. Phylogenetic analysis indicated that all H6N1 isolates had W312-like hemagglutinin and neuraminidase genes. However, reassortment of internal genes between different subtype virus lineages, including H5N1, H9N2, and other avian viruses, generated multiple novel H6N1 genotypes in different types of poultry. These novel H6N1/N2 viruses are double, triple, or even quadruple reassortants. Reassortment between a W312-like H6N1 virus and an A/quail/Hong Kong/G1/97 (HK/97)-like H9N2 virus simultaneously generated novel H6N2 subtype viruses that were persistent in poultry. Molecular analyses suggest that W312-like viruses may not be the precursors of HK/97 virus but reassortants from an HK/97-like virus and another unidentified H6 subtype virus. These results provide further evidence of the pivotal role of the live poultry market system of southern China in generating increased genetic diversity in influenza viruses in this region.
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Virus de la Influenza A/clasificación , Virus de la Influenza A/aislamiento & purificación , Gripe Aviar/epidemiología , Aves de Corral/virología , Animales , Antígenos Virales/análisis , Secuencia de Bases , China/epidemiología , Genes Virales , Genotipo , Virus de la Influenza A/genética , Gripe Aviar/virología , Datos de Secuencia Molecular , Filogenia , SerotipificaciónRESUMEN
Since an outbreak of severe acute respiratory syndrome (SARS) was averted in 2004, many novel coronaviruses have been recognized from different species, including humans. Bats have provided the most diverse assemblages of coronaviruses, suggesting that they may be the natural reservoir. Continued virological surveillance has proven to be the best way to avert this infectious disease at the source. Here we provide the first description of a previously unidentified coronavirus lineage detected from wild Asian leopard cats (Prionailurus bengalensis) and Chinese ferret badgers (Melogale moschata) during virological surveillance in southern China. Partial genome analysis revealed a typical coronavirus genome but with a unique putative accessory gene organization. Phylogenetic analyses revealed that the envelope, membrane, and nucleoprotein structural proteins and the two conserved replicase domains, putative RNA-dependent RNA polymerase and RNA helicase, of these novel coronaviruses were most closely related to those of group 3 coronaviruses identified from birds, while the spike protein gene was most closely related to that of group 1 coronaviruses from mammals. However, these viruses always fell into an outgroup phylogenetic relationship with respect to other coronaviruses and had low amino acid similarity to all known coronavirus groups, indicating that they diverged early in the evolutionary history of coronaviruses. These results suggest that these viruses may represent a previously unrecognized evolutionary pathway, or possibly an unidentified coronavirus group. This study demonstrates the importance of systematic virological surveillance in market animals for understanding the evolution and emergence of viruses with infectious potential.
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Coronavirus/genética , Felidae/virología , Mustelidae/virología , ARN Helicasas/genética , ARN Polimerasa Dependiente del ARN/genética , Proteínas Virales/genética , Animales , Secuencia de Bases , China , Coronavirus/clasificación , Coronavirus/enzimología , Coronavirus/aislamiento & purificación , Brotes de Enfermedades/historia , Evolución Molecular , Historia del Siglo XXI , Humanos , Datos de Secuencia Molecular , Filogenia , Síndrome Respiratorio Agudo Grave/epidemiología , Síndrome Respiratorio Agudo Grave/historia , Síndrome Respiratorio Agudo Grave/virologíaRESUMEN
Poor human-to-human transmission of influenza A H5N1 virus has been attributed to the paucity of putative sialic acid alpha2-3 virus receptors in the epithelium of the human upper respiratory tract, and thus to the presumed inability of the virus to replicate efficiently at this site. We now demonstrate that ex vivo cultures of human nasopharyngeal, adenoid and tonsillar tissues can be infected with H5N1 viruses in spite of an apparent lack of these receptors.
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Subtipo H5N1 del Virus de la Influenza A/metabolismo , Gripe Humana/transmisión , Receptores de Superficie Celular/metabolismo , Sistema Respiratorio/virología , Acoplamiento Viral , Células Cultivadas , Epitelio/virología , Histocitoquímica , Hong Kong , Humanos , Subtipo H1N1 del Virus de la Influenza A/metabolismo , Subtipo H3N2 del Virus de la Influenza A/metabolismo , Gripe Humana/metabolismo , Fitohemaglutininas/metabolismo , Replicación Viral/fisiologíaRESUMEN
A novel group 1 coronavirus was previously identified in bent-winged bats (Miniopterus spp.). Here, results are described from our ongoing surveillance of these bats for coronaviruses. These findings show that group 1 coronaviruses are endemic in these bat populations in Hong Kong. Genetic analysis of these viruses indicates that there are at least four different, but closely related, group 1 coronaviruses (bat-CoV 1A, 1B, HKU7 and HKU8) circulating in bent-winged bats. Phylogenetic analysis revealed that these group 1 bat coronaviruses have descended from a common ancestor and that these viruses have been established in these bats for a long period of time. These data provide a better understanding of the emergence and evolution of coronaviruses. Bat-CoV 1A and 1B were detected in apparently healthy Miniopterus magnater and Miniopterus pusillus, respectively, on repeated sampling occasions at a single habitat, suggesting that these viruses have established a persistent infection in these populations.
Asunto(s)
Quirópteros/virología , Coronavirus/aislamiento & purificación , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Coronavirus/clasificación , Coronavirus/genética , ADN Viral/genética , Evolución Molecular , Hong Kong , Datos de Secuencia Molecular , Proteínas de la Nucleocápside/genética , Filogenia , Homología de Secuencia de Aminoácido , Especificidad de la EspecieRESUMEN
Coronaviruses can infect a variety of animals including poultry, livestock, and humans and are currently classified into three groups. The interspecies transmissions of coronaviruses between different hosts form a complex ecosystem of which little is known. The outbreak of severe acute respiratory syndrome (SARS) and the recent identification of new coronaviruses have highlighted the necessity for further investigation of coronavirus ecology, in particular the role of bats and other wild animals. In this study, we sampled bat populations in 15 provinces of China and reveal that approximately 6.5% of the bats, from diverse species distributed throughout the region, harbor coronaviruses. Full genomes of four coronavirues from bats were sequenced and analyzed. Phylogenetic analyses of the spike, envelope, membrane, and nucleoprotein structural proteins and the two conserved replicase domains, putative RNA-dependent RNA polymerase and RNA helicase, revealed that bat coronaviruses cluster in three different groups: group 1, another group that includes all SARS and SARS-like coronaviruses (putative group 4), and an independent bat coronavirus group (putative group 5). Further genetic analyses showed that different species of bats maintain coronaviruses from different groups and that a single bat species from different geographic locations supports similar coronaviruses. Thus, the findings of this study suggest that bats may play an integral role in the ecology and evolution of coronaviruses.
Asunto(s)
Quirópteros/virología , Coronavirus/genética , Variación Genética , Animales , China , Coronavirus/clasificación , Coronavirus/aislamiento & purificación , Evolución Molecular , Genoma Viral , Datos de Secuencia Molecular , Filogenia , Prevalencia , ARN Viral/genética , Análisis de Secuencia de ADN , Proteínas Virales/genéticaRESUMEN
The Asian countries chronically infected with avian influenza A H5N1 are 'global hotspots' for biodiversity conservation in terms of species diversity, endemism and levels of threat. Since 2003, avian influenza A H5N1 viruses have naturally infected and killed a range of wild bird species, four felid species and a mustelid. Here, we report fatal disseminated H5N1 infection in a globally threatened viverrid, the Owston's civet, in Vietnam, highlighting the risk that avian influenza H5N1 poses to mammalian and avian biodiversity across its expanding geographic range.
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Conservación de los Recursos Naturales , Subtipo H5N1 del Virus de la Influenza A , Infecciones por Orthomyxoviridae/veterinaria , Viverridae/virología , Animales , Biodiversidad , Aves/virología , Femenino , Subtipo H5N1 del Virus de la Influenza A/clasificación , Subtipo H5N1 del Virus de la Influenza A/genética , Subtipo H5N1 del Virus de la Influenza A/aislamiento & purificación , Infecciones por Orthomyxoviridae/transmisión , Infecciones por Orthomyxoviridae/virología , Filogenia , Viverridae/anatomía & histología , Viverridae/fisiologíaRESUMEN
Highly pathogenic avian influenza virus H5N1 is endemic in poultry in East and Southeast Asia with disease outbreaks recently spreading to parts of central Asia, Europe and Africa. Continued interspecies transmission to humans has been reported in Vietnam, Thailand, Cambodia, Indonesia and China, causing pandemic concern. Here, we genetically characterize 82 H5N1 viruses isolated from poultry throughout Indonesia and Vietnam and 11 human isolates from southern Vietnam together with sequence data available in public databases to address questions relevant to virus introduction, endemicity and evolution. Phylogenetic analysis shows that all viruses from Indonesia form a distinct sublineage of H5N1 genotype Z viruses suggesting this outbreak likely originated from a single introduction that spread throughout the country during the past two years. Continued virus activities in Indonesia were attributed to transmission via poultry movement within the country rather than through repeated introductions by bird migration. Within Indonesia and Vietnam, H5N1 viruses have evolved over time into geographically distinct groups within each country. Molecular analysis of the H5N1 genotype Z genome shows that only the M2 and PB1-F2 genes were under positive selection, suggesting that these genes might be involved in adaptation of this virus to new hosts following interspecies transmission. At the amino acid level 12 residues were under positive selection in those genotype Z viruses, in the HA and PB1-F2 proteins. Some of these residues were more frequently observed in human isolates than in avian isolates and are related to viral antigenicity and receptor binding. Our study provides insight into the ongoing evolution of H5N1 influenza viruses that are transmitting in diverse avian species and at the interface between avian and human hosts.