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Open Access Research

Molecular evolution of the H6 subtype influenza a viruses from poultry in eastern China from 2002 to 2010

Guo Zhao, Xinlun Lu, Xiaobing Gu, Kunkun Zhao, Qingqing Song, Jinjin Pan, Quangang Xu, Zhiqiang Duan, Daxin Peng, Shunlin Hu, Xiaoquan Wang and Xiufan Liu*

Author Affiliations

College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China

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Virology Journal 2011, 8:470  doi:10.1186/1743-422X-8-470

Published: 14 October 2011

Abstract

Background

Although extensive data demonstrates that the majority of H6 duck isolates belonged to a single H6N2 virus lineage with a single gene constellation in southern China from 2000 to 2005, the prevalence of H6N2 virus in poultry in Eastern China is largely unknown.

Results

Epidemiology revealed that H6N2 viruses were the most frequently detected influenza subtypes in live bird markets from 2002 to 2008 in Eastern China, but from 2009 onwards, they were replaced with novel H6N6 viruses. We phylogenetically and antigenically analyzed 42 H6 viruses isolated mainly in domestic ducks from 2002 to 2010 in Eastern China. Surprisingly, none of these isolates grouped with the previously described H6N2 viruses which belonged to a single H6N2 virus lineage with a single gene constellation in domestic ducks in southern China from 2000 to 2005. Two distinct hemagglutinin lineages were identified and they all underwent frequent reassortment with multiple virus subtypes from the natural gene pool, but few reassortants were persistent or prevalent.

Conclusions

Five subtypes of H6 influenza viruses (H6N1, H6N2, H6N5, H6N6 and H6N8) cocirculated in Eastern China, which form a significant part of the natural influenza virus reservoir in domestic ducks, and significant viral reassortment is still ongoing in this species.

Keywords:
H6 influenza viruses; poultry; phylogenetic analysis; molecular evolution