Elsevier

Veterinary Microbiology

Volume 201, March 2017, Pages 225-230
Veterinary Microbiology

Short communication
Characterization of H5N1 highly pathogenic mink influenza viruses in eastern China

https://doi.org/10.1016/j.vetmic.2017.01.028Get rights and content

Highlights

  • This is the first report of mink H5N1 influenza virus in China.

  • XB15 and G15 viruses were highly pathogenic in chickens.

  • XB15 and G15 viruses showed moderate pathogenicity in mice without pre-adaptation.

  • Deliberate infection mimicked the natural infections in mink.

  • The mink viruses exhibited severe antigenic drift from the Re-6 vaccine.

Abstract

Members of the H5 subtype of highly pathogenic avian influenza viruses pose a great threat to both poultry and humans with severe consequences for both industry and public health sectors. Here, we isolated and characterized two H5N1 highly pathogenic influenza viruses in deceased mink from eastern China. Phylogenetic analyses showed that the G15 and XB15 viruses belonged to clade 2.3.2.1b and 2.3.2.1e, respectively. Both of these viruses were highly pathogenic in chickens. They were also shown to exhibit moderate to high pathogenicity in mice without pre-adaptation. Further, the mink influenza viruses had severe antigenic drift with corresponding Re-6 vaccine and current vaccines may fail to confer protection against these H5N1 viruses in poultry.

Introduction

Since the initial isolation of the H5N1 subtype of highly pathogenic avian influenza (HPAI) virus in geese in China, the H5N1 virus has been shown to be actively circulating in domestic and wild birds in many countries. Furthermore, H5N1 subtype HPAI viruses continue to undergo substantial evolution revealed by extensive genetic divergence and re-assortment between other subtypes of influenza viruses, giving rise to multiple viral clades and gene constellations. Moreover, these viruses have caused hundreds of human infections and deaths, and remain of global concern (Chen, 2009, Chen et al., 2007). Further, these viruses are capable of infecting a larger variety of animals. To date, most reported H5N1 infections and outbreaks have occurred in poultry and wild birds and a limited number of cases have been reported in mink. Prior to this report there was only a single report of mink H5N1 influenza virus (A/mink/Sweden/V907/2006(H5N1), V907) (Kiss et al., 2008). In 2015, we isolated two H5N1 mink influenza viruses from two mink farms in eastern China. Here, we have characterized the genetics, antigenicity, and pathogenicity of these two viruses in chickens, mice and mink.

Section snippets

Ethics statement

This study was conducted according to the animal welfare guidelines of the World Organization for Animal Health (Terrestrial Animal Health Code), and approved by the Committee on ethics from the China Animal Health and Epidemiology Center (Qingdao, China).

Virus isolation

On June 30, 2015, on a farm in eastern China, infected mink began to appear with clinical symptoms, including neurological signs and an abrupt increase in mink mortality. These events occurred less than two weeks after an H5N1 outbreak was

Molecular and phylogenetic analysis

The HA genes of G15 and XB15 viruses contained a series of basic amino acids (PQIERRRRKR/GLF and PQRERRRKR/GLF) at the cleavage sites, indicating that these two viruses were highly pathogenic. The receptor binding sites in the viral HA genes possess the residues Q226 and G228 (H3 numbering), which suggested that these two viruses would preferentially bind to avian-like receptors (Tharakaraman et al., 2013). The phylogenetic relationship of the HA gene sequences of the G15 and XB15 viruses in

Discussion

Since 1997, H5 subtype influenza viruses have been widely distributed and capable of infecting various types of animals. To date, most of the reported H5 infections and outbreaks have occurred in domestic poultry and wild birds with fewer reports in mink. Until recently, there existed only one mink H5 influenza virus (V907) in GenBank, which was isolated from Sweden in 2006. Here, we isolated two H5N1 influenza viruses, G15 and XB15, from mink in eastern China in 2015. Phylogenetic analyses

Conflicts of interest

None.

Acknowledgements

This research was supported by the Sci-tech Basic Work Project of Ministry of Science and Technology of China (SQ2012FY3260033).

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