Department of Veterinary Epidemiology and Preventive Medicine College of Veterinary Science, Tirupati - 517 502 (AP)
* Part of M.V.Sc thesis submitted by the first author to the Acharya N.G. Ranga Agricultural University, Rajendra Nagar, Hyderabad
In the present study, efficacy of six different IBD vaccination schedules were studied using intermediate and intermediate plus strains of vaccines either alone or in combination. Serum antibody levels of IBD were quantitated using IDEXX-ELISA kit (Flockcheck). The serum samples were found to be negative for maternally derived infectious bursal disease antibodies (IBD-MDA) by six weeks of age. In vaccinated groups, there was a gradual decrease in the ELISA titres from day old to third week. Sero-conversion of the vaccine virus was noticed during fourth week, reaching peak between eight to twelve weeks of age in different groups. There was no significant difference in the titres of different treatment groups. However, protective antibody titre was reported to be 400 or above in ELISA and also all the groups showed titres above protective level during entire period of study. Immunosuppressive effect of IBD vaccines was estimated based on the response of birds to Newcastle disease vaccination. There was only a moderate reduction in the HI titres of IBD vaccinated groups especially in group VI and VII when compared to the control. At no stage of the experiment the NDV-HI titres were found to be below protective levels. It is concluded that even though the intermediate plus vaccines cause some amount of bursal damage and a moderate immunosuppression, they can be used at the field level in the areas where IBD is endemic.
Vaccination schedules, IBD, ND immunity
