Infectious bursal disease: evaluation of pathogenicity of commercial vaccines from Brazil in specific pathogen free chichens

Abstract

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

Infectious Bursal Disease: Pathogenicity and Immunogenicity of Vaccines

“…The serological analyses also demonstrated that the intermediate vaccine induced a good production of anti-IBDV antibodies, which titers were similar to those obtained with the immunecomplex vaccine, which contains a "hotter"viral strain (2.995 and 2.921 log10, respectively). Studies have consistently reported the low pathogenicity of the intermediate vaccines in SPF chickens, and induction of antibody levels similar to those obtained with hot vaccines (Rautenschlein et al, 2003;Moraes et al, 2004;Padilha et al, 2005). However, it must be emphasized that commercially available intermediate vaccines may have different virulence degrees.…”

“…On the other hand, Moraes et al (2004) recommends caution when using live vaccines that may cause BF lesions, as the recovery of bursal follicles may be only partial. Moreover, according to Iván et al (2001), the pathological effects caused by immune-complex vaccines are different on SPF birds compared with commercial birds with maternal immunity.…”

Evaluation of follicular lymphoid depletion in the Bursa of Fabricius: an alternative methodology using digital image analysis and artificial neural networks

“…When the scores are grouped in a binary fashion, simulating a more realistic situation where the animal is either healthy or sick, the ANN accuracy increases significantly. This is reinforced by Pereira (2002) and Moraes et al (2004) who suggest that a bird should be considered sick only when BF using optical score is 3 or more. Therefore regrouping the scores in a binary fashion for ANN training does make sense.…”

Effect of Embryo Thermal Stimulation on the Serum Levels of Immunoglobulins and Corticosterone, and Organ Histopathology of 1 day-old Broilers

“…The bursa was scored according to the degree of lymphoid depletions as: score 1: 0-25%; score 2:26-50%; score 3: 51-80%; score 4: >81%.In addition, acute (edema, inter-follicular infiltration of inflammatory cells, follicular cysts, hyperemia) and chronic lesions (fibroplasia) of the bursa were determined according to Muskett et al (1979);Sterwart-Brown & Trampel (1990), and Moraes et al (2004).…”