The impact of the avian disease/virus (due to its acute clinical disease) on broiler production continues to be a significant viral challenge to global production and opens the door to potential industry-wide outbreak due to its association with high mortality and bursal degeneration and consequent immunosuppression. This study compared the relative protective efficacy of four commercially available infectious bursal disease vaccines for broiler chickens after a challenge from a local field isolate of IBDV. Clinical, mortality, gross pathologic, and histopathologic indicators were used to evaluate relative protection among vaccinated broiler groups. A total of 250 Ross 308 broiler chicks were divided into five groups (50 birds/group), with four groups receiving a different type of vaccine against Infectious Bursal Disease (IBD) and one group not receiving a vaccine at all. At 16 days of age, each of the four vaccinated groups was exposed orally to a previously verified field isolate of IBDV (IBDV virus), and the groups' response to the virus was evaluated according to clinical symptoms and signs, mortality, gross anatomical changes, and histopathological changes found in the bursa of Fabricius and in the kidneys of the birds. The vaccinated group had less severe clinical signs and lower mortality than the unvaccinated group. The unvaccinated control group experienced the highest mortality rate, 56%, while the vaccinated groups had lower mortalities via group 1 at 4%, group 2 at 12%, group 4 at 14%, and group 3 at 18%. The most severe lesions were found on both gross and microscopic examination of the bursa of Fabricius in the control group, while the vaccinated groups had various degrees of markedly reduced pathology. Group 1 had the least severe lesions and the greatest bursal and renal architecture preservation. To conclude, all tested commercial vaccines for Infectious bursal disease virus (IBDV) elicited varying levels of post-challenge protection; Group 1 produced the most significant overall level of protection under the experimental conditions assessed. Overall, vaccination resulted in reduced clinical severity, reduced mortality, and reduced tissue lesions.
Alaa Jawad Kadhim1* and Raed Hussin Salih Rabee2 (Thu,) studied this question.