Effect of anti-TP0136 antibodies on the progression of lesions in an infected rabbit model.

The effect of anti-TP0136 antibodies on the progression of syphilis is poorly understood. This study aimed to investigate the effect of anti-TP0136 antibodies on the progression of lesions in an infected rabbit model. Intramuscular injection of rTP0136 into rabbits in the immunized group (n = 4) elicited high titers of anti-TP0136 antibodies, and rabbits were then challenged with 105T. pallidum per site along their back. Lesion development was observed, and the injection sites were biopsied for tp0574 mRNA and histological analyses every week until the wound healed. The rabbits in the control group were injected with normal saline instead of rTP0136. Viable T. pallidum in the challenged rabbits was assessed with rabbit infectivity tests. The lesions in the immunized group took longer to heal than those in the control group (42 d vs. 28 d, P < 0.001) and had markedly higher levels of total cellular infiltrates. The mRNA level of tp0574 in the immunized group was significantly higher than that in the control group (P < 0.05). Viable T. pallidum was detected in rabbit lymph nodes in both the immunized and control groups. Our study showed that high titers of anti-TP0136 antibodies promoted the infiltration of inflammatory cells into local lesions and intensified tissue damage, thus delaying wound healing, and had no protective effect on the occurrence of syphilis in the rabbit model.