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Characterization of a reassortant #H3N2 swine #influenza virus with 2009 pandemic internal #genes and enhanced potential for zoonotic #risk

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By G.M.

 


Highlights

• A swine influenza virus H3N2 subtype was isolated during epidemiological survey.

• It is a complex and novel reassortant, and acquired accumulation of adaptive mutations.

• Both rescue and parent strains demonstrated efficient replication in mammalian cells.

• Key residues of the H3N2 HA collectively enhance the binding preference for human-type receptor.

• The rescued H3N2 cause significant pulmonary pathological damage in mice.


Abstract

Pigs serve as key "mixing vessels" for influenza A viruses, playing a critical role in cross-species transmission, while the H3N2 subtype represents an important lineage within the swine influenza virus (SIV) family. In this study, a novel reassortant H3N2 SIV strain, designated A/Swine/Jiangsu/YZ07/2024, was isolated from pigs exhibiting clinical symptoms in Northern Jiangsu, China during epidemiological survey. Genetic analysis revealed that the virus is a complex reassortant, with the internal genes (M, NP, PB1, PB2, PA) originated from the 2009 pandemic H1N1 lineage, the NS gene exhibiting a North American triple reassortant origin (human-avian-swine origin), and the HA and NA genes belonging to the human-like lineage. Although neither the rescued virus nor its parental strain could replicate effectively in chicken embryos and chicken cells, both demonstrated efficient replication in mammalian cells, reflected by the much higher polymerase activity in mammalian versus chicken cells. The key residues of HA protein (190D, 225D and 228S) collectively enhanced the binding preference for human-type α-2,6-linked sialic acid receptors, which was confirmed by receptor binding assays. Furthermore, mouse infection experiments using the rescued H3N2 demonstrated efficient viral replication in nasal turbinates and lung tissues, accompanied by significant pulmonary pathological damage. These findings indicate that the YZ07 strain, through the vast reassortment and accumulation of adaptive mutations, has acquired potential zoonotic risk, underscoring the importance of surveillance of swine influenza viruses.

Source: 


Link: https://www.sciencedirect.com/science/article/abs/pii/S0378113526000684?via%3Dihub

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