Syphilis Vaccine and Immune Mechanisms.

Development of an Effective and Practical Vaccine Against Experimental and Human Syphilis. No immunity to the intradermal challenge of 500 T. pallidum was demonstrated among rabbits vaccinated intramuscularly at 4-week intervals with a total of 4 vaccine doses, each containing an equal volume of approx. 4 x 10 to the 9th power gamma irradiated 1,000,000 rads, liquid-nitrogen preserved T. pallidum and an alginate-gluconate adjuvant each of the vaccinated animals developed VDRL and FTA-ABS antibodies, while none developed TPI antibody nor exhibited an anamnestic response following challenge. The possibility that irradiation with 1,000,000 rads damages the immunogens responsible for stimulating host-resistance, has led to the design of experiments in which T. pallidum gamma-irradiated with 650,000 rads will be utilized in the protocol described above in an effort to achieve a clearly demonstrable complete immunity. Author