Antigenic and Molecular Characterization of Avian Influenza A(H9N2) Viruses, Bangladesh

Karthik Shanmuganatham,Richard J Webby,Robert G Webster,Lisa Jones-Engel,S.M Rabiul Alam,Angie Danner,John Franks,Subrata Barman,Mohammed M Feeroz,M Kamrul Hasan,Mathieu Fourment,David Walker,Laura Mcclenaghan,Patrick Seiler,Pamela Mckenzie,Gavin J.D Smith,Scott Krauss

doi:10.3201/eid1909.130336

Abstract

Human infection with avian influenza A(H9N2) virus was identified in Bangladesh in 2011. Surveillance for influenza viruses in apparently healthy poultry in live-bird markets in Bangladesh during 2008–2011 showed that subtype H9N2 viruses are isolated year-round, whereas highly pathogenic subtype H5N1 viruses are co-isolated with subtype H9N2 primarily during the winter months. Phylogenetic analysis of the subtype H9N2 viruses showed that they are reassortants possessing 3 gene segments related to subtype H7N3; the remaining gene segments were from the subtype H9N2 G1 clade. We detected no reassortment with subtype H5N1 viruses. Serologic analyses of subtype H9N2 viruses from chickens revealed antigenic conservation, whereas analyses of viruses from quail showed antigenic drift. Molecular analysis showed that multiple mammalian-specific mutations have become fixed in the subtype H9N2 viruses, including changes in the hemagglutinin, matrix, and polymerase proteins. Our results indicate that these viruses could mutate to be transmissible from birds to mammals, including humans.

Highlights

Human infection with avian influenza A(H9N2) virus was identified in Bangladesh in 2011
Phylogenetic analyses of subtype H9N2 viruses isolated in China and the Middle East have shown that these viruses have undergone reassortment with other subtypes to generate multiple novel genotypes consisting of gene segments from different lineages [7,11,13,19,20]
The subtype H9N2 and H5N1 viruses were isolated from domestic poultry, mainly chickens and quail that were sampled in live-bird or pet markets (Table 1)

Summary

Introduction

Human infection with avian influenza A(H9N2) virus was identified in Bangladesh in 2011. Surveillance for influenza viruses in apparently healthy poultry in live-bird markets in Bangladesh during 2008–2011 showed that subtype H9N2 viruses are isolated year-round, whereas highly pathogenic subtype H5N1 viruses are co-isolated with subtype H9N2 primarily during the winter months. Molecular analysis showed that multiple mammalianspecific mutations have become fixed in the subtype H9N2 viruses, including changes in the hemagglutinin, matrix, and polymerase proteins. Avian influenza A(H9N2) viruses have been sporadically identified in pigs and humans, which suggests that some of these viruses have adapted to bind mammalian host receptors or have acquired mutations. Previous surveillance conducted at live-bird markets in Bangladesh found that avian influenza virus (AIV) is prevalent (23%); the low pathogenicity H9N2 subtype predominated, but other subtypes were. This surveillance report did not include information about the molecular properties of circulating subtype H9N2 viruses

Methods

Results

Conclusion