Abstract
The immune response to mycobacteria is complex and involves different T cell subsets. However, the key in the resistance against the bacillus is the establishment of a cell-mediated immune response. The objective of this study was to carry out a comparative analysis of different subpopulations of T lymphocytes and expression of cellular activation marker CD25 in calves vaccinated with BCG or with Mycobacterium bovis culture filtrate protein extract (CEPE) under field conditions. Three randomly assigned groups of 5 calves each were formed. One of them vaccinated subcutaneously with BCG, 104 CFU, another with 300 mg/ml of CFPE and the third group was the control. The results of monitoring the immune response were analyzed by MANOVA. The BCG induced IFN-y production in an earlier stage than the CFPE in the vaccinated groups with no statistical difference between them. The CFPE, besides inducing IFN-y production, enhanced antibody-mediated response (P<0.05). The group vaccinated with BCG showed a higher percentage of CD4 T lymphocytes in cultures stimulated with bovine PPD (P< 0.05). The rate of ys T lymphocyte activation was higher in CFPE group at d 30 post-vaccination, which increased for BCG group at d 60. Thus the dose of BCG vaccine used in the study was capable of inducing a proliferative response of CD4 T cells with higher levels of IFN-y than CFPE as immunogen, indicating a better immune system enhancement in calves vaccinated with BCG.
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