Efficacy of immune complex infectious bursal disease vaccines against very virulent infectious bursal disease virus challenge in commercial layer chicken

Abstract

The vaccination program for controlling Infectious bursal disease (IBD) was complicated due to high maternal antibody in day old chick. Therefore, our study was performed in young layer chickens with high maternal antibody as commonly seen in our country. The objective of this study was to determine the protective efficacy of immune complex IBD vaccines against very virulent infectious bursal disease virus (vvIBDV) challenge in commercial layer chickens. As immune complex vaccine A was recommended in layers by the company, the first aim of the study was to compare immune complex vaccine A (group 1) and B (group 3). The result showed a similar survival rate but group 1 had better body weight gain than group 3. Moreover, the negative control group had better body weight than group 3 but not significantly different. The serology profiles of group 1 and 3 were not significantly different. Bursa size, bursa to body weight ratios and bursal histopathological lesion scores of group 1 and 3 were not significantly different as well. The second aim was to compared immune complex vaccine A (vaccination one time at 1-day-old (group 1)) with immune complex vaccine A (vaccination at 1-day-old) and booster with live IBD vaccine at 25-days-old (group 2). The chickens which received a booster vaccine had a better survival rate, body weight gain and milder bursal lesion scores after receiving vvIBDV. In conclusion, vaccine A showed better weight gained in layers, while, the immune complex vaccine with a booster of live vaccine showed more promise on IBD protection.