IMMUNIZATION AGAINST BRUCELLA INFECTION II

Abstract

A streptomycin-dependent mutant (SMd), isolated from a virulent Brucella melitensis culture for use as a living avirulent vaccine, whose characteristics were previously reported (Herzberg and Elberg, J. Bact. 66: 585-599, 1953) was studied for its capacity to immunize mice and guinea pigs against challenge with virulent Br. melitensis. Significant protection (77.8 and 72.3%) of mice was achieved by admn. of 1010 viable SMd against a challenge which infected 70 and 90% of the non-immunized controls. Two inoculations of 1010 organisms protected mice (93% and 78%) against a challenge which infected 94 and 100% of the control animals. Admn. of streptomycin to immunized mice failed to enhance the immunity. The streptomycin-dependent mutant protected guinea pigs only against small doses of virulent organisms. The capacities of these 2 spp. of animals to be immunized is discussed. The authors propose the admn. of a SMd mutant as a method of presenting the animal with the living organism containing its complement of antigens unaltered by any special method of extraction or killing.