Host Innate Immune Response of Geese Infected with Clade 2.3.4.4 H5N6 Highly Pathogenic Avian Influenza Viruses

Abstract

Since 2014, highly pathogenic avian influenza (HPAI) H5N6 viruses have circulated in waterfowls and caused human infections in China, posing significant threats to the poultry industry and the public health. However, the genetics, pathogenicity and innate immune response of H5N6 HPAIVs in geese remain largely unknown. In this study, we analyzed the genetic characteristic of the two H5N6 viruses (GS38 and DK09) isolated from apparently healthy domestic goose and duck in live poultry markets (LPMs) of Southern China in 2016. Phylogenetic analysis showed that the HA genes of the two H5N6 viruses belonged to clade 2.3.4.4 and were clustered into the MIX-like group. The MIX-like group viruses have circulated in regions such as China, Japan, Korea, and Vietnam. The NA genes of the two H5N6 viruses were classified into the Eurasian sublineage. The internal genes including PB2, PB1, PA, NP, M, and NS of the two H5N6 viruses derived from the MIX-like. Therefore, our results suggested that the two H5N6 viruses were reassortants of the H5N1 and H6N6 viruses and likely derived from the same ancestor. Additionally, we evaluated the pathogenicity and transmission of the two H5N6 viruses in domestic geese. Results showed that both the two viruses caused serious clinical symptoms in all inoculated geese and led to high mortality in these birds. Both the two viruses were transmitted efficiently to contact geese and caused lethal infection in these birds. Furthermore, we found that mRNA of pattern recognition receptors (PRRs), interferons (IFNs), and stimulated genes (ISGs) exhibited different levels of activation in the lungs and spleens of the two H5N6 viruses-inoculated geese though did not protect these birds from H5N6 HPAIVs infection. Our results suggested that the clade 2.3.4.4 waterfowl-origin H5N6 HPAIVs isolated from LPMs of Southern China could cause high mortality in geese and innate immune-related genes were involved in the geese innate immune response to H5N6 HPAIVs infection. Therefore, we should pay more attention to the evolution, pathogenic variations of these viruses and enhance virological surveillance of clade 2.3.4.4 H5N6 HPAIVs in waterfowls in China.

Emergence of a young case infected with avian influenza A (H5N6) in Anhui Province, East China during the COVID‐19 pandemic

“…No mutations were found in both H5N6 HPAV strains. However, mutations in S137A, T160A, and S227R have been found in our strain, and studies have shown that these mutations make H5N6 AIV easier to adapt to mammalian hosts 15,16 . In addition, the AH38 H5N6 virus had the characteristic NA stalk deletion, although no amino acid substitution associated with resistance to NA inhibitors was observed.…”

“…However, mutations in S137A, T160A, and S227R have been found in our strain, and studies have shown that these mutations make H5N6 AIV easier to adapt to mammalian hosts. 15 , 16 In addition, the AH38 H5N6 virus had the characteristic NA stalk deletion, although no amino acid substitution associated with resistance to NA inhibitors was observed. The K389R, V598T mutations in PB2 protein and the N409S mutation in PA protein, which had been reported to enhance growth capacity in human and mammalian systems, were observed in the AH38 virus.…”

Genetic characteristics of waterfowl-origin H5N6 highly pathogenic avian influenza viruses and their pathogenesis in ducks and chickens

“…Viral RNA was extracted from the allantoic fluid using the RNA extraction kit (Vazyme, China) and reverse transcribed using reverse transcriptase (M-MLV; Vazyme). Eight AIV genes were amplified using universal primers ( Wu et al, 2020 ). Purification of polymerase chain reaction products was accomplished using the DNA purification kit (ThermoFisher Scientific, United States).…”

Proteomics analysis of duck lung tissues in response to highly pathogenic avian influenza virus

“…Significant upregulation of MDA5 and LGP2 have been observed in the lung tissues of Muscovy ducks infected with HPAI H5N1 infection [39,40]. In ducks, both MDA5 and LGP2 activate IRF-7-dependent signaling pathway and induce interferons (IFNs) as well as interferon-stimulated genes (ISGs) production, both of which mediate the antiviral and pro-inflammatory responses during HPAI H5N1 virus infection [8,[39][40][41][42][43][44]. The tripartite motif (TRIM) family of proteins, tripartite motif 25 (TRIM25) and ubiquitin carboxyl-terminal hydrolase 15 (USP15) were expressed in the duck lung tissues (Figure 6).…”