Epidemiology, evolution, and biological characteristics of H6 avian influenza viruses in China

ABSTRACT

H6 avian influenza virus (AIV) is one of the most prevalent AIV subtypes in birds globally. To investigate the current situation and characteristics of H6 AIVs circulating in China, we analysed the epidemiology, genetic evolution and pathogenic features of this subtype. During 2000-2021, H6 subtype AIVs spread widely through Southern China and presented high host diversity. On analysing 171 H6 viruses isolated during 2009-2021, dynamic reassortments were observed among H6 and other co-circulating AIV subtypes, and these generated a total of 16 different genotypes. A few H6N6 strains possessed L226 and S228 mutations of hemagglutinin (H3 numbering), which may enhance the affinity of H6 viruses to human receptors. H6N6 viruses also exhibited divergent pathogenicity and growth profiles in vivo and in vitro. Some of the H6N6 viruses could infect mice without mammalian adaptation, and even caused death in this species. Therefore, our study demonstrated that the H6 AIVs posed a potential threat to human health and highlighted the urgent need for continued surveillance and evaluation of the H6 influenza viruses circulating in the field.

KEYWORDS:

• H6 avian influenza viruses
• epidemiology
• evolution
• pathogenicity

Acknowledgement

We sincerely acknowledge the authors and laboratories for sharing the H6 AIVs sequences in GISAID and GenBank database. This article is solely the responsibility of the authors and does not represent the views of China CDC and other organizations.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Key Research and Development Program of China [grant no 2021YFC2300100], and the National Natural Science Foundation of China [grant no 81971941 and 81961128002].