COMPARATIVE IMMUNO PATHOLOGICAL AND IMMUNOSUPPRESSIVE EEFECTS OF THREE DIFFERENT GUMBORO VACCINE STRAINS AGAINST NEWCASTLE DISEASE VACCINA TION IN BROILERS

This project was carried out to study the comparative immunosuppressive effects of three different Gumboro live vaccine strains on Newcastle disease (NO) vaccination. A total of 100 chicks were divided into four equal groups (A, B, C and O). Birds of all the groups were vaccinated against ND on 5th and 21st day of age. Specific Gumboro vaccine strain was given to specific group at 14th and 28th day of age. Group A, Band C were vaccinated with 228-E, D- 78 and Bursine-2, respectively, while group D was kept as control. Immune organs including bursa, thymus and spleen were examined for their gross and, histopathological changes, before and after Infectious Bursal disease (IBO) vaccination. For this purpose, these organs were collected at 13th, 17th and 31st days of age. At 13th day (before 1BD vaccination) no gross and histopathological lesions were observed in any bird of any group. At 17th and 31st day, severe lesions were noted in group A, moderate lesions in group B, mild lesions in group C and no lesions were observed in immune organs of group D. Haemagglutination inhibition (HI) test showed that 228-E vaccine strain, (group A) was highly immunosuppressive, D- 78 vaccine strain (group B) was less immunosuppressive while Bursine-2 vaccine strain (group C) was least immunosuppressive. No humoral immunosuppression was observed in unvaccinated control group D. This study suggests the use of Bursine-2 strain of IBD vaccine in a flock having risk of ND infection, as it has least immunosuppressive effect against ND vaccination