Various strains of BCG vaccine and genetic control of the immune response of mice.

Numerous field trials of BCG vaccine, undertaken to evaluate its effectiveness in the prophylaxis of human tuberculosis, indicated that the levels of protection achieved were not uniform. Most probable factors influencing these results are: partial protection due to atypical mycobacteria, tuberculosis expectancy in different population, nutritional and socio-economic factors, potency of BCG vaccines, and genetic factors controlling the host immune response. Specific and non specific hallmarks of cell-mediated immunity after BCG infection were analysed in various outbred, inbred and recombinant lines of mice, testing the capacity of different preparations and strains of BCG vaccine. Results of such studies did show that the by far most important factor involved the type of immune response related to gene(s) controlling the natural resistance and the expression of C.M.I. Consequences for future mass and individual BCG vaccination as well as the proper integration of BCG vaccination in antituberculous policy are discussed.