Studies on Immunity in Experimental Syphilis : II. TREPONEMA PALLIDUM IMMOBILIZATION (TPI) ANTIBODY AND THE IMMUNE RESPONSE

Abstract

Ten rabbits infected with the Nichols strain of T. pallidum were cured 24 weeks later with an injection of 1.2 million units of Bicillin, and challenged 48 weeks after treatment with intratesticular injection of virulent T. pallidum. Seven animals demonstrated immunity and 3 asymptomatic syphilitic infection. There were no symptomatic infections. Both TPI and RPC F antibody increased as immunity to T. pallidum increased, whereas the reagin levels declined sharply during the development of maximum acquired resistance. Anamnestic responses to challenge occurred in all 3 tests among both the immune and partially-immune rabbits. No significant serologic difference was observed between the responses of the immune rabbits and those asymptomatically infected.