Abstract: Objective: To investigate the pathological changes of mjor organs in rabbit models inoculated with Treponema pallidum which has different continuous passages and is treated with different drugs and doses. Methods: One New Zealand rabbit was selected to be dissected. The heart, liver, spleen and kidney from primary, first and second generation group and negative control group in testis-inoculated groups were used for the pathological examination. In dorsal skin-inoculated groups, these organs were taken from one rabbit selected from positive control group, two doses of procaine benzylpenicillin and ceftriaxone sodium groups. After fixed by 10% formalin solution, these organs were dehydrated, paraffine-embedded and sliced for HE staining. Results: After infected with Treponema pallidum for two weeks, the heart, liver, and kidney tissue of the rabbit were infiltrated with inflammatory cells，but no pathological changes were observed in spleen tissue. And also there were no significant difference in the inflammatory changes of the organs between the three passages of Treponema pallidum. After treated with drugs for 12 weeks, some major organs of the rabbit were infiltrated with inflammatory cells, but no obvious infiltration of inflammatory cells were observed in these tissue of the infected rabbit treated with ceftriaxone sodium after the RPR titer was negative for 11 weeks. Conclusion: Pathologic observation is not essential for pharmacological evaluation, but the results can verify the efficacy of the treatment.

Key words: Treponema pallidum, New Zealand rabbit, infected models, pathologic change