Immune-Related Gene Expression in Ducks Infected With Waterfowl-Origin H5N6 Highly Pathogenic Avian Influenza Viruses.

Siyu Wu,Zhuoliang He,Bingbing Zhao,Zhifeng Qin,Junsheng Zhang,Wanting He,Jianni Huang,Ming Liao,Peirong Jiao,Zhiting Liu,Zuxian Chen,Weiqiang Li

doi:10.3389/fmicb.2019.01782

Abstract

Clade 2.3.4.4 H5 avian influenza viruses (AIVs) are widely prevalent and of significant concern to the poultry industry and public health in China. Nowadays, the clade 2.3.4.4 H5N6 virus has become a dominant AIV subtype among domestic ducks in southern China. We found that waterfowl-origin clade 2.3.4.4 H5N6 viruses (A/goose/Guangdong/16568/2016, GS16568 and A/duck/Guangdong/16873/2016, DK16873) isolated from southern China in 2016 could replicate in multiple organs of inoculated ducks. DK16873 virus caused mild infections and killed 2/5 of inoculated ducks, and GS16568 virus did not kill inoculated ducks. In addition, the two viruses could be transmitted via direct contact between ducks. DK16873 and GS16568 viruses killed 2/5 and 1/5 of contact ducks, respectively. Furthermore, ducks inoculated with the two H5N6 viruses exhibited different expressions of immune-related genes in their lungs. The expression of RIG-I, TLR3 and IL6 was significantly upregulated at 12 h post-inoculation (HPI) and most of the tested immune-related genes were significantly upregulated at 3 days post-inoculation (DPI). Notably, the expression of RIG-I and IL-6 in response to DK16873 virus was significantly higher than for GS16568 virus at 12 HPI and 3 DPI. Our research have provided helpful information about the pathogenicity, transmission and immune-related genes expression in ducks infected with new H5N6 AIVs.

Highlights

Avian influenza virus (AIV) is a negative-sense RNA virus that belongs to the orthomyxoviridae family (Webster et al, 1992)
As a natural host of AIVs, ducks can survive even when they are infected with HPAIVs (Chen et al, 2004)
Previous studies have shown that clade 2.3.4.4 H5N2, H5N5 and H5N8 highly pathogenic avian influenza (HPAI) viruses isolated from China from 2010 to 2016 exhibited mild to low virulence in ducks and were not lethal (Zhao et al, 2013; Liu et al, 2018)

Summary

Introduction

Avian influenza virus (AIV) is a negative-sense RNA virus that belongs to the orthomyxoviridae family (Webster et al, 1992). AIV can be classified into highly pathogenic avian influenza (HPAI) virus and low pathogenic avian influenza (LPAI) virus based on pathogenicity in chickens. Since the first H5N1 HPAI virus was detected in 1996, these viruses have been prevalent among poultry in Asia, Europe, and Africa. This situation has resulted in heavy losses in the poultry industry (Alexander and Brown, 2009). These viruses can cause human infections and are of great concern to public health (Peiris et al, 2007). Since 2008, clade 2.3.4 H5N2 (Zhao et al, 2012), H5N5 (Gu et al, 2011), and H5N8 (Song et al, 2015) viruses have been detected in China

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