PATHOGENICITY AND IMMUNOSUPPRESSIVE EFFECT OF DIFFERENT VACCINES OF INFECTIOUS BURSAL DISEASE VIRUS
B. Zahid1*, A. Aslam2, Habib-ur-Rehman3, J. I. Qazi1, N. Ahmad4, C. Ara1, R. Akhtar2, and U. Bacha3
1Department of Zoology, University of the Punjab, Lahore, 54590, Punjab, Pakistan
2Department of Pathology, 3Department of Physiology, 4Department of Parasitology
University of Veterinary and Animal Sciences Lahore, 54000, Punjab, Pakistan
*Corresponding Author’s email: Bzemail@example.com
The current experiment was conducted to compare the efficacy of different of Infectious Bursal Disease (IBD) vaccines having different IBD virus strains against field virus. A total of two hundred, one-day old broiler chickens were divided into four groups (50 birds each group). Group A was subcutaneously vaccinated with immune complex vaccine at 1 day of age. The groups B and C were vaccinated with live IBD vaccines D78 and 228E at 20th and 16th day of age according to Deventer formula. The blood samples were taken randomly from five birds of each group at day 7, 14, 21, 28 and 35 to evaluate anti-IBDV antibody titer by ELISA. Five birds from each group were killed on days 14, 21, 28 and 35 to check bursa to body weight ratio, bursometery, gross and histopathological lesions scoring. Ten birds from each treatment group were challenged with virulent field IBDV on 28 day. On day 35 significantly (P<0.05) higher ELISA antibody titer was observed in group A vaccinated with immune complex vaccine. Bursa to body weight ratio of group A was significantly higher (P<0.05) as compared to other vaccinated groups. Mild to moderate histopathological lesions such as lymphocytic depletion, epithelial necrosis and mononuclear cells infiltration, fibrous tissue proliferation and edematous fluid were observed in vaccinated groups. The live and immune complex IBD vaccine induced adequate protection after challenged. The high mortality and morbidity observed in control group D1 in one week of challenge. The morbidity rate in group A1 and Group C1 was 90% and in group B1 was 70%. It concluded that conventional live IBD vaccines cause more severe damage in bursal follicles as compared to immune complex vaccine. Immune complex vaccine can be safer for day-old chick regardless of maternal derived antibody titers.
Key words: Infectious Bursal Disease, Vaccines, ELISA, Bursa to body weight ratio