Impact of Dose and Route of administration on Antibody Responses of Chickens Inoculated with inactivated Avian Influenza H5 Vaccine.

Abstract Avian influenza viruses (AIV) poses significant threats to human and animal lives globally, and in spite of availability of vaccines, only few studies have established the role of passively acquired antibodies in the protection of chickens in sub Saharan Africa. The present study evaluated the influence of dose and route of administration of AI H5 inactivated vaccine on the humoral immune response of ISA brown chickens. Ninety “one-day-old” chickens were purchased from three major commercial hatcheries A, B and C (n = 30 chicks per hatchery), respectively. Results showed significant differences (P < 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 < 0.001) between the chicks at 21, 28, 35 and 42 days of age. Furthermore, intra- and inter route significant differences (P < 0.001) were detected between the chicks at 21 and 35 days of age. Overall, the AI H5 vaccine studied had variable outcomes and poorly immunogenic. Further studies should be conducted to characterize the T- and B-lymphocytes in chickens post AI H5 vaccines administration, and evaluate the sequence homologies between imported AI H5 vaccines and circulating AIV strains in Nigeria.