Syphilis causes adverse pregnancy outcomes, FG-4592 mouse including fetal deaths and stillbirths, as well as enhanced HIV transmission [9] and [26], and the global disability-adjusted life-years (DALYs) lost from syphilis are the highest of all curable STIs [27]. Screening and treatment programs in antenatal care clinics can effectively prevent the adverse outcomes of syphilis in pregnancy, but they are inadequately implemented in many settings [28]. To develop an investment case for syphilis vaccine development, modeling is needed to understand the comparative

benefits and economic rationale of a vaccine versus a screening program, or both, for syphilis control or potential eradication [29]. In addition, the role of syphilis vaccine as part of a vaccine against multiple STIs should be explored. As discussed by Cameron in this issue, barriers to development of a syphilis vaccine include an insufficient number of basic researchers, technical difficulties

associated with experimentation on T. pallidum, and a lack of industry interest in the field [30]. Nonetheless, a useful rabbit model for syphilis infection has enabled excellent insights into the correlates of disease protection and has yielded some promising vaccine candidates [30]. Two candidate vaccines are currently being evaluated in Fludarabine the rabbit model, although only a limited number of rabbits have been assessed thus far [30]. There have been no human clinical trials. Thus, in addition to needing vaccine studies in a larger numbers of rabbits over a longer time period, it will also be Methisazone important to facilitate exchange of information and samples between basic research laboratories and clinical settings, to translate important findings from animal models to humans. Access to human samples from clearly defined clinical cohorts will allow study of human immunologic markers and how markers vary according to previous infection. Based on the identified knowledge gaps and needs described above, participants of the 2013 STI Vaccine Technical Consultation discussed

key priorities for future STI vaccine development, evaluation, and introduction. These discussions formed the basis for a roadmap outlining the most important next steps for advancing new STI vaccines. Although the vaccine science is in different stages for the five STIs, the roadmap summarizes critical overarching action points related to the epidemiologic and scientific groundwork for STI vaccine development, preferred product characteristics and clinical development, advanced planning for vaccine introduction, and vaccine funding and investment strategies. Many of these priorities can be pursued in parallel to expedite development of STI vaccines. Meeting participants agreed that existing epidemiologic data show that STIs are a global threat to sexual and reproductive health.