Ribonucleic acid antigen from the Reiter treponeme used in an ELISA for antibodies in syphilis.

Purified RNA from Treponema phagedenis biotype Reiter was used as antigen in an enzyme-linked immunosorbent assay (ELISA) for IgG antibodies in syphilis. The RNA ELISA was compared with the fluorescent treponemal antibody absorption test (FTA-ABS), the Treponema pallidum immobilization test (TPI), and with two ELISAs using purified flagellum from the Reiter treponeme as antigen (flagellum ELISA), and sonified Reiter treponeme culture as antigen (sonicate ELISA). A total of 729 sera from patients with and without syphilis were studied. The RNA ELISA had a lower sensitivity (P less than 0.01) in primary syphilis than the flagellum ELISA, the sonicate ELISA, and the FTA-ABS. In treated syphilis the RNA ELISA was also less sensitive than the TPI (P less than 0.01).