Antibody responses to two commercial oil emulsion avian influenza vaccines (H9N2) in broiler chicks

Avian Influenza disease has economic and public health significance. Avian influenza virus subtype H9N2 became endomic in Iran. Vaccination policy is used for control of it. Efficacy of avian influenza vaccine has an important role in control of disease, decreasing risk of infection and shedding of avian influenza virus, and then monitoring vaccine effectiveness is necessary. In this research, antibody responses to two commercial avian influenza vaccines were studied in broiler chickens. For this reason, 90 one-day-old commercial broiler chicks were divided to three groups. Group one and two received vaccines A and B respectively on day 14, and group three was not received vaccine. Serologic study with hemagglutination inhibition test (HI) was achieved weekly from day 14 until 49. The mean HI titers were significantly different (P<0.05) between group 1 and other groups three and four weeks post vaccination and also between vaccinated groups and non-vaccinated group five weeks post vaccination. Results indicated that both vaccines induced highest titers after 5 weeks of vaccination, although the titers were not induced protective immunity; also it was cleared that there was not interfering between maternal antibody and active immunity. In conclusion, with attention to this point that the two vaccines are commercial, the quality of them was regularly evaluated by producers, then, the most important reason for low quality of the vaccines probably is storage or transport of the vaccines in inappropriate temperature.