“…Lack of a readily available inbred strain of rabbits has been a stumbling block in our understanding of the effector mechanisms operative in the process of immunity in syphilis. We have shown that Treponema pallidum infection in an inbred strain of guinea pigs, although milder than in rabbits, mimics critical aspects of the early stage of venereal syphilis in humans when carried out under optimal conditions (15). A number of basic parameters such as median infective dose, clinical course of infection, and humoral and cellular responses have been explored in different strains of guinea pigs (for a review, see reference 13).…”