Study on the experimental simultaneous infections of avian influenza virus H9N2 subtype with Vaccinal viruses of ND and IB in broiler.

Avian influenza subtype H9N2 is caracterized as non-highly pathogenic avian influenza (non-HPAI). This virus has been isolated in commercial poultry flocks of Iran since 1998. H9N2 virus infection is prevalence in commercial chickens of Iran and causes sever syndromes and noticeable mortality in broilers especially during 3wk to 6wk old. The causes of mortalities haven&rsquot been determined yet, but there are documentations that some factors such as bad management, environmental stresses, concurrent infections with bacterial, viral agents and live vaccines cause sever signs and high mortality. In this study regards to significance of concurrent infections and several vaccinations with live vaccines, including Hitchner B1, Lasota and H120 during their 42 days life, we have evaluated changes in severity and mortality of H9N2 sub-type of avian influenza with simultaneous infection with Hitchner B1 and Lasota strains of Newcastle disease and H120 of infectious bronchitis vaccines. In this study 630 chickens were monitored, divided in 5 groups (18 pens), for 42 days. During this period chickens were inoculated intraocularly with 108 EID50 H9N2 virus and one dose of Hitchner B1, Lasota (ND) and H120 (IB) vaccines with different program in 5 studying and control groups. We have studied the relationship between concurrent infection of H9N2 sub-type of avian influenza with B1, Lasota and H120 vaccines and concluded the severity of disorders according to clinical signs, mortality, macroscopic lesions, virus isolation and FCR. In this study regards to significance of concurrent infections and several vaccinations with live vaccines, including B1, Lasota and during their 42 days life, the experimental chickens have been revealed a little changes in severity and mortality of H9N2 sub-type of avian influenza with simultaneous infection with Hitchner B1 and Lasota strains of Newcastle disease and H120 strain of Infectious brnchitis vaccines.Statistical analysis of our data showed, a little increasing of the severity of disease, mortality and reduction of FCR.