Genetic and antigenic analysis of the highly pathogenic avian influenza H5N8 virus clade 2.3.4.4b isolated from waterfowl in Egypt during 2022; evidence of brain-specific HA mutations

Abstract

. F244L, I248S, K234R) compared to tracheal isolates, which suggested possible roles in neurotropism. Internal genes revealed mammalian adaptation markers such as 504 V (PB2), 127 V and 672 L (PA), and 133 G (PB1), with additional unique mutations observed H5N8 strains isolated from geese in 2022. Reassortment analysis for the 8 gene segments showed that H5N8 duck strains isolated in 2018 belonged to genotype G1, while the 2022 strains belonged to genotype G4. This confirmed changes after 2018 and reflecting continuous viral evolution through segment reassortment.5. Antigenic analysis revealed that the newly introduced H5N1 virus clade 2.3.4.4b is antigenically similar with H5N8 viruses from the same clade, while different from viruses in other clades.