Treponema pallidum membrane protein A ELISA: a new test for screening and diagnosis of syphilis.

A new ELISA test system for screening antibodies directed against Treponema pallidum is presented. The ELISA is based on a recombinant DNA-derived T. pallidum membrane protein A (TmpA). It makes the production of the kit easier as it abandons the necessity to culture T. pallidum in living animals. The specificity and sensitivity of the ELISA are comparable with those of the TPHA and FTA-ABS. The test gives only a positive result when there are antibodies against the TmpA antigen and, therefore, it gives in screening (e.g. blood donors) no false-positive reaction in persons who, due to an old well-treated infection, have a so-called serological scar. As these donors are noninfective, they should be concerned as negative in syphilis screening.