Abstract Since its emergence in 1996, the H5 avian influenza virus (AIV) A/Goose/Guangdong/1/1996 (Gs/GD) haemagglutinin (HA) has evolved into over 30 genetically and antigenically distinct clades , including the widespread clade 2.3.4.4b. Vaccination is widely used in endemic regions to reduce poultry losses and zoonotic risk . However, the evolving antigenic diversity and global co-circulation of multiple clades challenges protective efficacy of poultry vaccines with poor antigenic matching to field strains, resulting in immune escape and vaccine failure. This study aimed to improve vaccine seed selection by identifying HA epitopes contributing to inter-clade antigenic differences. Recombinant clade-representative viruses were generated using HA genes from circulating H5 AIVs via reverse genetics with A/Puerto Rico/8/1934 (PR8) internal and neuraminidase genes. Antigenic relationships were assessed using haemagglutination inhibition (HI) assays with homologous and heterologous chicke...
Media Monitoring for Signals about Emerging Threats