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Emerging seasonal and pandemic influenza infections

Long-term co-circulation of multiple influenza A viruses in pigs, Guangxi, China

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Article: 2337673 | Received 14 Dec 2023, Accepted 27 Mar 2024, Published online: 09 Apr 2024
 

ABSTRACT

Influenza A viruses (IAVs) pose a persistent potential threat to human health because of the spillover from avian and swine infections. Extensive surveillance was performed in 12 cities of Guangxi, China, during 2018 and 2023. A total of 2540 samples (including 2353 nasal swabs and 187 lung tissues) were collected from 18 pig farms with outbreaks of respiratory disease. From these, 192 IAV-positive samples and 19 genomic sequences were obtained. We found that the H1 and H3 swine influenza A viruses (swIAVs) of multiple lineages and genotypes have continued to co-circulate during that time in this region. Genomic analysis revealed the Eurasian avian-like H1N1 swIAVs (G4) still remained predominant in pig populations. Strikingly, the novel multiple H3N2 genotypes were found to have been generated through the repeated introduction of the early H3N2 North American triple reassortant viruses (TR H3N2 lineage) that emerged in USA and Canada in 1998 and 2005, respectively. Notably, when the matrix gene segment derived from the H9N2 avian influenza virus was introduced into endemic swIAVs, this produced a novel quadruple reassortant H1N2 swIAV that could pose a potential risk for zoonotic infection.

Acknowledgements

We thank Dr. Dev Sooranna of Imperial College and YMUN for the English language editing of the manuscript. Chongqiang Huang, Liangzheng Yu, and Yi Xu contributed equally to this article.

Disclosure statement

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

Data availability

Accessions with relevant swine influenza viruses obtained from GISAID and IRD are included in Supplementary Tables S2.

Additional information

Funding

This work was supported by the NIAID supported Centers of Excellence for Influenza Research and Response (CEIRR, contract no. 75N93021C00014), Guangxi Natural Science Foundation (grant number 2023GXNSFDA026042) and the National Natural Science Foundation of China (32160825).