Studies on Immunity in Experimental Syphilis: I. IMMUNOLOGIC RESPONSE OF RABBITS IMMUNIZED WITH REITER PROTEIN ANTIGEN AND CHALLENGED WITH VIRULENT TREPONEMA PALLIDUM

Abstract

The authors attempted to determine the clinical and serologic response of rabbits immunized with the serologically active protein antigen extracted by D''Allessandro from the Reiter strain (RP), and then challenged with virulent T. pallidum. 18 of the 19 rabbits immunized over a 5 week period with a total of 3.25 ml of sterile, serologically-active RP antigen developed dark-field positive lesions upon challenge, and only 1 rabbit was considered immune. No significant difference between the immunized and control rabbits was observed in the size of the lesions or in the duration of the incubation period. Both reagin and TPI antibodies failed to develop during immunization. Most of the rabbits were seroreactive to the TPCF antigen, but there was no significant rise after attempts at immunization. The RPCF titer on the other hand rose abruptly within 2 weeks after the initiation of immunization. The presence of this RPCF antibody did not protect the rabbits from syphilitic infection on challenge.