Histopathological evaluation of the effects of live Infectious bursal disease vaccine originated from WF2512 strain on bursa Fabricius in the broilers

Infectious bursal disease (IBD) is a viral disease that causes significant economic losses in young chickens, characterized by lymphoid depletion and inflammation in the bursa Fabricius (BF). The incidence of the disease shows an increasing trend all over the world. Active and passive immunization is very important as well as strict hygiene measures in combating outbreaks. However, the fact that live-attenuated vaccines (mild, intermediate, hot) used for this purpose cause immunosuppression because of bursal damage is seen as an important limitation. In this study, it was aimed to histopathologically investigate the effects of commercial IBD vaccines originating from WF2512 (intermediate plus/hot, orally with drinking water) on BF under routine broiler rearing conditions. For this, BFs of 55 Ross 308 hybrid breed chickens (50 test, 5 controls) from five different broiler farms were used. In addition to standard vaccines, the IBD vaccine was given on day 15, and five samples from each farm were obtained 10 days later (25th day). After the first sampling, the second BF sampling was performed at the age of 38 days. Histopathological bursal lesion score was applied to evaluate the effectiveness of the vaccine. Accordingly, it was determined that the bursal lesion score, which increased slightly to moderately in the first samples, decreased in the second samples (27-61%). This was accepted as an indication that the bursal damage, which increased with IBD vaccine administration, diminishes over time and that histological regeneration was increased.