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Evolution of highly pathogenic H5N1 avian influenza viruses in Vietnam between 2001 and 2007
Journal article   Open access   Peer reviewed

Evolution of highly pathogenic H5N1 avian influenza viruses in Vietnam between 2001 and 2007

Xiu-Feng Wan, Tung Nguyen, C Todd Davis, Catherine B Smith, Zi-Ming Zhao, Margaret Carrel, Kenjiro Inui, Hoa T Do, Duong T Mai, Samadhan Jadhao, …
PloS one, Vol.3(10), pp.e3462-e3462
2008
DOI: 10.1371/journal.pone.0003462
PMCID: PMC2565130
PMID: 18941631
url
https://doi.org/10.1371/journal.pone.0003462View
Published (Version of record) Open Access

Abstract

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.
Vietnam Poultry Humans Genotype Influenza in Birds - transmission Influenza A Virus, H5N1 Subtype - genetics Poultry Diseases - virology Topography, Medical Influenza A Virus, H5N1 Subtype - isolation & purification Biological Evolution Animals Virulence - genetics Poultry Diseases - transmission Genes, Viral Influenza in Birds - virology Influenza, Human Influenza A Virus, H5N1 Subtype - pathogenicity

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