Immunogenicity of inactivated H۵ avian influenza vaccine used in commercial laying pullet in Tehran province

Highly pathogenic avian influenza (HPAI) is a viral disease caused by some H۵ and H۷ subtypes of influenza virus type A in most species of birds, especially poultry. HPAI viruses are amongst the most challenging viruses that threaten both human and animal health. Consequently, various strategies such as the use of vaccines have been proposed to control the disease. After a catastrophic pandemic and the failure of conventional methods (elimination and extermination) in Iran, multiple vaccines has been used to control the disease. This study investigates the immunogenicity of two recombinant inactivated commercial vaccines of H۵N۱ and H۵N۳ subtypes in laying pullet flocks in Tehran Province, Iran. From ۳۲ halls in ۶ breeding units of laying pullets, ۳۲۰۰ sera and ۸۰۰ tracheal and cloacal swabs were collected. After collecting the samples, Serum neutralisation (SN) and hemagglutination inhibition (HI) tests were conducted on sera to determine the serum titers of H۵ specific antibody obtained from vaccine inoculation in three steps: before, after first vaccination and after the second vaccination (booster). SN and HI tests were carried out by the alpha and beta methods on the pooled samples by the vaccine type (as antigen for HI and SN), and the results were compared. The PCR was performed on the tracheal and cloacal swab samples to possibly detect the HA (H۵) virus in the studied flocks. The HI test results showed that both vaccines had a Serum antibody titre above ۵ (log۲) after two vaccination rounds, indicating a desirable immunogenic response. The SN test results also showed a neutralisation index above ۱۰۴.۵ for both vaccines, indicating more than ۵۰% reduction in antigenicity of the virus. The PCR results were negative. This study was the first investigation of immunogenicity following two-time vaccination against H۵ subtype vaccines in Iranian poultry flocks, indicated suitable antibody titer against the influenza virus in vaccinated flocks.

کلیدواژه ها:

Highly pathogenic avian influenza ، vaccine ، Heamagglutination inhibition ، Serum neutralisation ، PCR