Avian Influenza Virus Threat to the Egyptian Poultry Industry: An Epidemiological and Molecular Study

Avian Influenza Virus (AIV) poses a significant threat to Egypt's poultry industry. This study combined molecular analysis and field surveillance to investigate the occurrence and genetic diversity of AIV in both domestic poultry and wild birds. The study investigated H5 and H9 subtypes, known to cause substantial health and economic problems in various poultry species. Researchers characterized the viruses by analyzing the receptor binding domain and major antigenic sites within the hemagglutinin protein (HA) of selected H5 and H9 isolates. This analysis aimed to identify substitutions that might affect viral attachment and immune response, providing insights into the effectiveness of currently licensed vaccines in Egypt. Our findings revealed the circulation of AIV H5N8 in four domestic flocks, co-infections of H5N1 with Newcastle Disease Virus (NDV) in three domestic flocks, and a co-infection of H5N1 and H9N2 in one domestic flock. Additionally, H9N2 was found to be widespread in twenty-two domestic flocks and was also detected in wild bird species, including the Common Moorhen and Eurasian Coot. The detection of AIV H9 in wild birds suggests their crucial role in AIV transmission and potential for facilitating the emergence of new viral strains or subtypes. Genetic analysis of the HA protein in selected isolates revealed sequence differences compared to local vaccine strains. These findings highlight the urgent need to revise vaccine designs in Egypt to protect poultry flocks and potentially prevent zoonotic spillover events.