Influence of the nature of the antigen on the boosting of responses to mycobacteria in M. bovis-BCG vaccinated cattle.

Mycobacterium bovis is the causative agent of bovine tuberculosis (TB) and of a proportion of human TB. Protection against TB requires Th1 responses and worsening of disease is associated with Th2 responses. To help clarify the nature of the response to mycobacteria, the responses from M. bovis-BCG vaccinated cattle boosted with live mycobacteria (BCG), bacterial soluble antigens (PPD) or PBS were evaluated. The results indicated that macrophages may be the major cell population ingesting and presenting mycobacteria in BCG boosted animals, while B-cells seem able to ingest and present PPD to T-cells in PPD boosted animals.