Impact of dose and route of administration on antibody responses of chickens inoculated with inactivated Avian Influenza H5 vaccine.

Abstract

Background: The present study evaluated the influence of dose and route of administration of a commercial inactivated avian influenza virus (AIV) H5 vaccine on the humoral immune response of ISA brown chickens. Methods: Ninety “one-day-old” chickens were purchased from three commercial hatcheries (n = 30 chicks per hatchery), respectively, and chicks were vaccinated with either 0.2, 0.5 or 0.7 ml of the vaccine via either the intramuscular or subcutaneous route at days 14 and 28, respectively. Vaccinal antibody titres in chicks’ sera were quantified using an indirect ELISA kit at 14 (before vaccination), 21, 28, 35 and 42 days of age. Results: Results showed significant differences (p < /em> < 0.001) in the mean antibody titre levels at day 21 of age between chicks from hatcheries C (2,205.0 ± 409.1) and A (57.7 ± 49.9) at 21 days of age when either 0.2 ml or 0.5 ml of the vaccine was administered IM or SC. In addition, there were intra- and inter dose significant differences ( p < /em>< 0.001) between the chicks at 21, 28, 35 and 42 days of age. Furthermore, intra- and inter route significant differences (p < /em>< 0.001) were detected between the chicks at 21 and 35 days of age. Conclusion:  Overall, the AIV H5 vaccine studied had variable outcomes and was poorly immunogenic. Recommendation: Further studies should be conducted to characterize the T- and B-lymphocytes in chickens post AIV H5 vaccines administration, and evaluate the sequence homologies between imported AIV H5 vaccines and circulating AIV strains in Nigeria.