Key result
Strong commercial IBD vaccines induced more pronounced bursal lesions and higher antibody titers compared to intermediate vaccines and controls in specific pathogen free chickens.
Why the study?
Do different commercial IBD vaccines cause varying degrees of pathogenicity and immune response in specific pathogen-free chickens?
Do different commercial IBD vaccines cause varying degrees of pathogenicity and immune response in specific pathogen-free chickens?
Strong commercial IBD vaccines induce higher antibody titers but cause more severe bursal injuries in specific pathogen-free chickens compared to intermediate vaccines.
Highlights a trade-off between enhanced immunogenicity and increased tissue damage; leaves open whether intermediate.
Infectious Bursal Disease (IBD) is a chicken disease economically important for the poultry industry in function of the immune depression that it causes. Disease control is made with different vaccines and vaccination programs. In present work, the pathogenicity of 3 intermediate vaccines (I1, I2 and I3), 2 intermediate more pathogenic (IP1 and IP2) and 3 vaccines containing strong virus (F1, F2 and F3) was evaluated. Birds vaccinated with IP1, IP2, F1, F2 and F3 showed significantly lower bursa size in relation to control animals and animals vaccinated with I1, I2 and I3. On the other hand, vaccines I1 and I3 induced antibody titers higher than the control and lower than I2, IP1, IP2, F1, F2 and F3. Histological scores showed that vaccines I1, I2 and I3 induced similar injury degree, although I2 and I3 were not different from the control, whereas I1 was slightly different. Strong vaccines induced more pronounced lesions than the other tested vaccines. These findings suggest that strong vaccines are able to cause severe bursal injuries. However, bursometry and relative weight of the bursa of Fabricius were considered inadequate to evaluate vaccine pathogenicity. Moreover, strong vaccines induced higher antibody titers than the other vaccines, although some intermediate vaccines induced similar titers.
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Padilha et al. (2004) studied Infectious Bursal Disease. Commercial IBD vaccines vs. Control was evaluated on Pathogenicity (bursa size, antibody titers, histological scores). Strong commercial IBD vaccines induced more pronounced bursal lesions and higher antibody titers compared to intermediate vaccines and controls in specific pathogen free chickens.
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