Infectious bursal disease: evaluation of maternal immunity and protection by vaccination of one-day old chicks against challenge with a very virulent virus isolate

Abstract

Broiler chicks belonging to two poultry companies, A and B, with different breeders' vaccination programs were challenged with a very virulent strains of infectious bursal disease virus (vvIBDV), genotyped as G11. Birds were separated in four groups, two vaccinated at the first day of life and two unvaccinated. They were then challenged at the 1st, 4th, 7th, 10th, 13th, 16th, 19th and 22nd days. At every day of challenge, before and after the procedure, the following data were collected from each group: Bursa of Fabricius (BF) relative weight, BF diameter, BF for histologie examination, serum for measuring antibodies against IBDV through the ELISA and clinical evaluation of IBD. The results obtained have shown a non-significant drop in antibody level between the vaccinated and the unvaccinated groups. When analyzing the different results, it could be established that an ELISA titre of 3,4 log10 was the cutoff point between healthy and sick birds. Regression equations were built to determinate the best moment for vaccination and also the ELISA log titre birds what could present in a given age. Based on that, chicks from Company A should receive a vaccine against IBD from the 6th to 7th day of age, while the ones from Company B should get it between the 11th and the 12th day of age. Finally, the overall results suggest that the birds should not be vaccinated at one day old, and also that the breeders' different vaccination schemes resulted in progenies with different levels of maternal protection, and as a consequence the same vaccination plan should not be applied indiscriminately to broilers from different poultry companies

Histopathological and immunohistochemical diagnosis of infectious bursal disease in poultry birds

“…The scoring of the various IBD lesions in bursa of Fabricius was done, as shown in Table-2 , based on the criterion and method as adopted by previous researchers such as Moraes et al . [ 34 ].…”

Determination of the optimal time of vaccination against infectious bursal disease virus (Gumboro) in Algeria

“…Early vaccine failed to stimulate the immune system in the chicks because maternal antibody reacts with live vaccine virus and becomes neutralised or interferes with MDA (Zhuo et al 1998 ). Several studies under laboratory conditions have indicated that high MDA at the time of IBDV vaccination might interfere with the vaccine response, neutralises the vaccine virus and delays or even prevents the induction of humoral immunity (Hair-Bejo et al 2004 ; Jung 2006 ; Morães et al 2005 ). This means that the vaccination in the first days failed to offer the chick any protection against disease.…”

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

“…Currently, the evaluation of bursal lymphoid depletion depends on a subjective histological evaluation therefore susceptible to errors. In fact, a lesion score has been reported in order to minimize possible subjective errors (Pereira 2002, Moraes et al 2005.…”