AUTHOR=He Yuxing , Chen Dejun , Fu Yue , Huo Xinzhuo , Zhao Feijun , Yao Ling , Zhou Xiuping , Qi Pengfei , Yin Haoquan , Cao Longgu , Ling Hui , Zeng Tiebing TITLE=Immunization with Tp0954, an adhesin of Treponema pallidum, provides protective efficacy in the rabbit model of experimental syphilis JOURNAL=Frontiers in Immunology VOLUME=14 YEAR=2023 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2023.1130593 DOI=10.3389/fimmu.2023.1130593 ISSN=1664-3224 ABSTRACT=

Syphilis, a chronic multisystemic disease caused by spirochete Treponema pallidum subspecies pallidum infection, continues to be a serious global health problem and congenital syphilis remains a major cause of adverse outcomes in pregnancy in developing countries. The development of an effective vaccine is the most cost-effective way to eliminate syphilis, but so far has been elusive. Here, we evaluated the immunogenicity and protective efficacy of Tp0954, a T. pallidum placental adhesin, as a potential vaccine candidate in a New Zealand White rabbit model of experimental syphilis. Animals immunized with recombinant Tp0954 (rTp0954) produced high titers of Tp0954-specific serum IgG, high levels of IFN-γ from splenocytes and specific splenocyte proliferation response when compared to control animals immunized with PBS and Freund’s adjuvant (FA). Furthermore, rTp0954 immunization significantly delayed the development of cutaneous lesions, promoted inflammatory cellular infiltration at the primary lesion sites, as well as inhibited T. pallidum dissemination to distal tissues or organs when compared with that of the control animals. In addition, the naïve rabbits receiving popliteal lymph nodes from Tp0954-immunized, T. pallidum-challenged animals were not infected by T. pallidum, confirming sterile immunity. These findings suggest that Tp0954 is a potential vaccine candidate against syphilis.