Effect of three different routes of administration on the immunogenicity of infectious bursal disease vaccine.

The immune response of three groups of 10 chicks, vaccinated at age of 2 weeks against infectious bursal disease (Gumboro disease) via the oral, intramuscular and ocular routes, is compared. The vaccine was prepared by the NVRI (Vom, Nigeria). All chicks in the three groups remained seronegative 3 weeks after primary vaccination. However, precipitating antibodies were present in birds which received a booster dose at the age of 6 weeks. Post-vaccination seroconversion was observed at the age of 6 weeks in 70% of the birds vaccinated via the ocular route. This rate increased to 80% during the two following weeks and then decreased to 55.6% until the 10th week. In the groups vaccinated by the oral and intramuscular routes, the seroconversion rate in the 7th week was 30 and 33.3%, respectively, but increased to 87.5% in both groups at the end of the 10th week. Considering the age factor in the susceptibility of chicks to infectious bursal disease, the authors recommend the ocular route as the most effective for vaccination.