Avian influenza (Al) is a viral disease with worldwide distribution. It is caused by influenza A viruses of the family Orthomyxoviridae. In May 1998, clinical signs and high mortaity in broiler chickens in Iran were associated with H9N2 avian influenza subtype. Vaccination was adapted as an alternative method to control it in poultry industry. The aim of this study was to compare the Immunogenesis of different local and imported H9N2 avian influenza vaccines. Arian broiler chickens were divided randomly into 21 groups of 30 birds. Each group received standardized dose of Lohmman, Ivaz, and FVM vaccines in 1,5,10,15 and 20 days old by subcutaneously in the nape of the neck. Sera were collected from each chicken for antibody analysis 1,2,3,4 and 5 weeks post vaccination. The sera were tested for antibodies against
avian influenza H9N2 subtype with hemagglutination
inhibition (HI) tests. Antiboby levels in broiler chickens immunized with local H9n2 avian influevza vaccines were higher than those Immunized with imported H9N2 avian influenza vaccines (P<0.000l). The vaccinated chickens were challenged with local H9N2 influenza virus. To detect viral shedding feces, lungs and kidneys were tested. In all vaccinate groups, viral shedding was reduced. The local H9N2 avian influenza vaccines in broiler chickens induced a significantly immune response and less viral shedding in comparison with imported H9N2 avian influenza vaccine (P<0.001). On the basis of these results, it is suggested that vaccination of broiler chickens with inactivated local vaccine may be useful in control of Al in poultry industry in IRAN.