title: Multiple introductions of highly pathogenic avian influenza H5N1 viruses into Bangladesh.
abstract: Highly pathogenic H5N1 and low pathogenic H9N2 influenza viruses are endemic to poultry markets in Bangladesh and have cocirculated since 2008. H9N2 influenza viruses circulated constantly in the poultry markets, whereas highly pathogenic H5N1 viruses occurred sporadically, with peaks of activity in cooler months. Thirty highly pathogenic H5N1 influenza viruses isolated from poultry were characterized by antigenic, molecular, and phylogenetic analyses. Highly pathogenic H5N1 influenza viruses from clades 2.2.2 and 2.3.2.1 were isolated from live bird markets only. Phylogenetic analysis of the 30 H5N1 isolates revealed multiple introductions of H5N1 influenza viruses in Bangladesh. There was no reassortment between the local H9N2 influenza viruses and H5N1 genotype, despite their prolonged cocirculation. However, we detected two reassortant H5N1 viruses, carrying the M gene from the Chinese H9N2 lineage, which briefly circulated in the Bangladesh poultry markets and then disappeared. On the other hand, interclade reassortment occurred within H5N1 lineages and played a role in the genesis of the currently dominant H5N1 viruses in Bangladesh. Few 'human-like' mutations in H5N1 may account for the limited number of human cases. Antigenically, clade 2.3.2.1 H5N1 viruses in Bangladesh have evolved since their introduction and are currently mainly homogenous, and show evidence of recent antigenic drift. Although reassortants containing H9N2 genes were detected in live poultry markets in Bangladesh, these reassortants failed to supplant the dominant H5N1 lineage.
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, TN 38105, USA.
authors.forename: Atanaska
authors.initials: A
authors.lastname: Marinova-Petkova
authors.affiliation: Department of Zoology, Jahangirnagar University , Dhaka-1342, Bangladesh.
authors.forename: Mohammed M
authors.initials: MM
authors.lastname: Feeroz
authors.affiliation: Department of Zoology, Jahangirnagar University , Dhaka-1342, Bangladesh.
authors.forename: S M
authors.initials: SM
authors.lastname: Rabiul Alam
authors.affiliation: Department of Zoology, Jahangirnagar University , Dhaka-1342, Bangladesh.
authors.forename: M
authors.initials: M
authors.lastname: Kamrul Hasan
authors.affiliation: Department of Zoology, Jahangirnagar University , Dhaka-1342, Bangladesh.
authors.forename: Sharmin
authors.initials: S
authors.lastname: Akhtar
authors.affiliation: National Primate Research Center, University of Washington , Seattle, WA 98195, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Jones-Engel
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, TN 38105, USA.
authors.forename: David
authors.initials: D
authors.lastname: Walker
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, TN 38105, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: McClenaghan
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, TN 38105, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Rubrum
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, TN 38105, USA.
authors.forename: John
authors.initials: J
authors.lastname: Franks
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, TN 38105, USA.
authors.forename: Patrick
authors.initials: P
authors.lastname: Seiler
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, TN 38105, USA.
authors.forename: Trushar
authors.initials: T
authors.lastname: Jeevan
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, TN 38105, USA.
authors.forename: Pamela
authors.initials: P
authors.lastname: McKenzie
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, TN 38105, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Krauss
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, TN 38105, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Webby
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, TN 38105, USA.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Webster
keywords: Bangladesh; H5N1; H9N2; clades; live bird markets; phylogenetic tree; reassortment