Phylogenetic tracing and biological characterization of a novel clade 2.3.2.1 reassortant of H5N6 subtype avian influenza virus in China

Abstract

In recent years in China, clade 2.3.4.4 H5N6 plus clade 2.3.2.1 H5N1 subtype highly pathogenic avian influenza (HPAI) viruses have gradually become endemic in poultry, and their co-circulation could inevitably facilitate the gene reassortment between each other. During our routine surveillance in live poultry markets (LPMs) in eastern China in 2017-2018, a novel reassortant H5N6 strain with the HA gene derived from clade 2.3.2.1 was isolated from the cloacal swabs of apparently healthy ducks.Phylogenetic tracing analysis indicated that another two clade 2.3.2.1 H5N1 strains with divergent lineages of PB1 gene and one clade 2.3.4.4 H5N6 isolate of the dominant genotype sharing spatio-temporal proximity were intimately involved in the generation of this rarely reported clade 2.3.2.1 H5N6 reassortant. Distinct with the other three HPAI H5 viruses showing moderate virulence in mice, the H5N1 strain of the homologous internal gene constellation against the clade 2.3.2.1 H5N6 reassortant was highly pathogenic, which might probably attribute to the H3 subtypederived PB1 gene. However, as compared to the clade 2.3.4.4 H5N6 ancestor, the clade 2.3.2.1 H5N6 reassortant displayed a broader tissue distribution and higher viral titres in mice, which could likely facilitate the viral maintenance and spread in nature. Therefore, our results highlight that continuous epidemiological survey of H5 subtype HPAI viruses in LPMs needs to be strengthened to prevent the potential poultry or even public health threat of the novel reassortants from endemic viruses.

Virulence and transmission characteristics of clade 2.3.4.4b H5N6 subtype avian influenza viruses possessing different internal gene constellations

“…In addition, these studies indicated that H9N2 internal genes might contribute to viral dissemination and adaptation. Other than H9N2, LPAIV including H3, H4, and H6 subtypes, were found to participate in the genetic reassortment of H5N6 viruses [ 21 , 31 , 32 ]. Furthermore, several human H5N6 isolates possessed internal genes derived from LPAIV.…”

Susceptibility of common dabbling and diving duck species to clade 2.3.2.1 H5N1 high pathogenicity avian influenza virus: an experimental infection study

“…These results and further observations of M807 infections in migratory dabbling and diving ducks are expected to provide a comprehensive understanding of HPAIV ecology in field settings. [11,12]. A clade 2.3.2.1 HPAIV was also isolated from a domesticated Muscovy duck (Cairina moschata) in our surveillance study in Vietnam (A/Muscovy duck/Vietnam/LBM992c/2017 (H5N1); accession numbers: LC656314-21).…”

“…Although clade 2.3.2.1 HPAIVs have become minor in comparison with the globally circulating clade 2.3.4.4 HPAIVs, they have perpetuated in poultry populations in East Asian countries; Ge et al . reported clade 2.3.2.1 H5N2 and H5N6 HPAIVs in China from 2017 to 2018 [ 11 , 12 ]. A clade 2.3.2.1 HPAIV was also isolated from a domesticated Muscovy duck ( Cairina moschata ) in our surveillance study in Vietnam (A/Muscovy duck/Vietnam/LBM992c/2017 (H5N1); accession numbers: LC656314–21).…”

Monoclonal antibody targeting a novel linear epitope on nucleoprotein confers pan-reactivity to influenza A virus

“…In avian species, H9N2, H5Nx, and H7N9 are the major subtypes that seriously affect poultry industry worldwide (Carnaccini and Perez 2020 ; Lee et al 2017 ; Lee et al 2021 ). Noteworthy, various HA clades such as clade 2.3.4.4 and clade 2.3.2.1, plus multiple NA subtypes such as H5N1, H5N6, and H5N8, have additionally increased the complexity of the highly pathogenic avian influenza (HPAI) H5Nx viruses (Antigua et al 2019 ; Ge et al 2021 ; Ge et al 2022 ). As for the novel reassortant H7N9 virus which emerged in 2013, it has evolved from low pathogenicity avian influenza (LPAI) to HPAI form and exhibited obvious antigenic variation to challenge the vaccine efficiency (Liu et al 2021 ; Wu et al 2021 ; Yin et al 2021 ).…”