Genotype 4 Eurasian avian-like H1N1 swine influenza virus (G4 EA H1N1) (G4 EA H1N1)

Genotype 4 (G4) Eurasian avian-like (EA) H1N1 swine influenza virus is a reassortant strain of the Influenza A virus that has become the dominant genotype in Chinese swine populations since 2016 (Sun et al., 2020; PNAS). This virus possesses a unique genetic constellation consisting of an EA-lineage surface proteins (hemagglutinin and neuraminidase), a 2009 pandemic-like internal core (PB2, PB1, PA, NP, and M), and a triple-reassortant non-structural (NS) gene (CDC, 2020; NIH, 2022). It is considered a significant pandemic threat because it preferentially binds to human-type sialic acid (SAα2,6Gal) receptors and demonstrates efficient replication and aerosol transmission in mammalian models such as ferrets (Cusabio, 2020; PNAS, 2020). While primarily a swine pathogen, serological evidence indicates that approximately 10.4% of tested swine workers in certain regions of China have antibodies to the virus, highlighting a high risk for zoonotic spillover (PNAS, 2020; Pig333, 2020). Currently, seasonal human influenza vaccines provide little to no cross-protective immunity against G4 strains, making the development of specific candidate vaccine viruses a public health priority (CDC, 2020; NIH, 2022). The virus remains susceptible to existing influenza antivirals, including neuraminidase inhibitors such as oseltamivir and zanamivir, as well as cap-dependent endonuclease inhibitors like baloxavir marboxil (bioRxiv, 2022; CDC, 2020). Continued systematic surveillance of swine populations and close monitoring of human infections are essential to mitigate the risk of a future pandemic (Virology, 2024; CDC, 2020).

Other names

G4 swine flu virusG4 reassortant EA H1N1 virusEA H1N1 G4G4 virusEurasian avian-like H1N1 genotype 4Genotype 4 Eurasian avian-like H1N1 virus

Neuraminidase inhibition; Cap-dependent endonuclease inhibition