A Directed Search for a Treponema pallidum Antigen Test

The only validated tests available for assessing if syphilis has responded to therapy are the “nontreponemal” tests. These tests frequently give false positive and false negative results. Despite these problems, the “non-treponemal” tests are also one of the two categories of tests used in the initial diagnosis of syphilis. In this prospective observational study we aim to develop a new test that is able to detect the presence of Treponema pallidum subsp. pallidum’s(T.pallidum) antigen in the serum. In this Search for a T.pallidum Antigen Test (SeTPAT) study, we plan to set up a prospective observational study of patients diagnosed with syphilis within our HIV positive cohort at the Institute of Tropical Medicine (Work Package 1 – WP1). Targeted proteomic studies including mass spectrometry will be used to assess which T.pallidum antigens have the greatest diagnostic potential for evaluating the initial diagnosis and response to therapy of T.pallidum infection (WP2). WP3 will use this information to construct a specific T.pallidum capture ELISA – using polyclonal antibodies from rabbit infection as the capture antibodies and monoclonal antibodies as the detection antibodies. WP4 will evaluate the immunological correlates of a successful versus a serofast response to T.pallidum therapy. We aim to translate this test into an ELISA that will take the place of, or complement, the “nontreponemal” tests in the initial diagnosis and subsequent follow up of patients with syphilis.