Immunogenetic insights into matching bivalent inactivated Payavax G79® for sustainable poultry vaccination against NDV-GVII and H9N2.

Newcastle disease virus (NDV) and H9N2 avian influenza virus (AIV) have a severe impact on the poultry industry. This Iranian study evaluated Payavax G79®, an inactivated bivalent vaccine, in broiler chickens across five provinces. Vaccinated chicks showed robust antibody responses to both viruses via HI tests at 25 and 32 days post-vaccination. The vaccine provided complete protection against challenge with velogenic NDV genotype VII. However, H9N2 infection occurred on three farms, with 2% mortality. Molecular analysis of NDV isolates revealed amino acid substitutions in the hemagglutinin-neuraminidase protein that potentially enhance antigenicity. This study shows that Payavax G79® is highly immunogenic and provides significant protection against both NDV and H9N2 AIV under field conditions in Iran.