National Institute of Animal Health (NIAH)

Topics in Animal Health Research 2002

03. Development of highly efficacious recombinant infectious bursal disease vaccine

Japanese

Marek's disease herpesvirus is a vaccine vector of great promise for chickens; however, complete protection against foreign infectious diseases has not been achieved. In this study, two herpesvirus of turkey recombinants (rHVTs) expressing large amounts of infectious bursal disease virus (IBDV) VP2 antigen were constructed (rHVT-cmvVP2 and rHVT-pecVP2).  The rHVT-pecVP2 expressing the VP2 antigen approximately four times more than rHVT-cmvVP2 in vitro, induced complete protection against a lethal IBDV challenge in chickens, whereas rHVT-cmvVP2 induced only 58% protection.  All of the chickens vaccinated with rHVT-pecVP2 had a protective level of antibodies to the VP2 antigen at the time of challenge, whereas only 42 and 67% of chickens vaccinated with rHVT-cmvVP2 or the conventional live IBDV vaccine, respectively, had the antibodies.  The antibody level of chickens vaccinated with rHVT-pecVP2 increased for 16 weeks after vaccination, and the peak antibody level persisted throughout the experiment.  The serum antibody titer at 30 weeks of age was about 20 or 65 times higher than that of chickens vaccinated with rHVT-cmvVP2 or the conventional live vaccine, respectively.  The rHVT-pecVP2, isolated consistently for 30 weeks from the vaccinated chickens, expressed the VP2 antigen after cultivation, and neither nucleotide mutations nor deletion in the VP2 gene was found.  These results demonstrate that the amount of VP2 antigen expressed in the HVT vector was correlated with the vaccine efficacy against a lethal IBDV challenge, and the complete protective immunity is likely to persist for the life of the chickens. (Pathogenic Virus Section, Department of Infectious Diseases Tel +81-29-838-7760)

Reference:

Tsukamoto et al. (2002) J. Virol. 76:5637-5645.

Centers・Institutes