Abstract: 【Abstract】 Objective To establish an in vivo diffusion model of Treponema pallidum （Tp） in New Zealand rabbits. Methods A standard strain of Tp （Nichols strain） was recovered in the testes of New Zealand rabbits, and isolated and passaged continuously. The suspensions of the second-passage Tp were collected and inoculated onto the dorsal skin of New Zealand rabbits. After 21-day infection, the New Zealand rabbits were anesthetized and sacrificed, blood samples were collected, and skin tissues at the infection site as well as liver, spleen, testes and lymph nodes were aseptically resected. Real-time fluorescence-based quantitative PCR was performed to detect the spread of Tp in different tissues and organs. Results On day 21 after infection with Tp, skin lesions such as indurations and ulcers were seen at all inoculated sites of New Zealand rabbits. Pathological examination showed a lot of inflammatory cells in the infected lesions, mainly including plasma cells, macrophages and lymphocytes. Real-time fluorescence-based quantitative PCR revealed a large number of Tp in tissues and organs, such as liver, spleen and testes. Conclusion After inoculation with Tp in the dorsal skin of New Zealand rabbits, Tp could spread to the liver, spleen, testes and other tissues and organs through blood and lymph nodes, and the in vivo diffusion model of Tp strains in New Zealand rabbits was successfully constructed.

Key words: Treponema pallidum, Disease models, animal, Rabbits, Pathologic processes