Immunological Responses of a Single Vaccination of Live NDVAC 1174/08 Vaccine on Specific-Pathogen–Free Chickens (SPF) and Village Chickens (VC)

Abstract

The ND vaccine 1174/08, produced by the Veterinary Research Institute (VRI), was evaluated for it’s for immune response. This study aimed to compare the immunological responses of specific-pathogen-free chickens (SPF) and village chickens (VC) to the ND vaccine of 1174/18 strain (NDVAC 1174/08). A total of nine SPF chickens and nine VC, both negative for ND antibodies and aged 14 and 20 days old respectively, received a single oral vaccination at a dose of 10^6.5 / bird. The same method was used to administer PBS to an unvaccinated control group. Serum samples from each group were collected at regular intervals up to 49 days post-vaccination (dpv). The haemagglutination inhibition (HI) assay was utilised to detect ND antibodies in all serum samples. Throughout the course of the trial, no clinical symptoms orfatalities were observed in the vaccinated group. The findings indicated that SPF chicken displayed an HI titre log₂ of ? 4, with a mean of HI titre (log₂) of 5.17 at 14 dpv, while the VC exhibited no HI antibodies at the same time point. The VC demonstrated an HI titre log₂ of 4 at 21 dpv, with a mean HI titre (log2) of 5.22. No ND HI antibodies were present in the unvaccinated group. The immunity was sustained with a single vaccination dosage until 49 dpv. Upon evaluation at 49 dpv, the HI antibody profile of the NDVAC 1174/08 vaccine revealed that SPF chickens were protected, exhibiting a mean HI titre (log₂) of 4.17, while the VC showed a titre (log₂) of 4.38.