Enzyme-linked immunosorbent assay for the detection of serum antibody to outer membrane proteins of Treponema pallidum

A highly sensitive enzyme-linked immunosorbent assay was used for the analysis of serum IgG reactivity against specific immunogenic Treponema pallidum proteins. Outer membrane treponemal proteins purified by preparative SDS-polyacrylamide gel electrophoresis were used as antigenic probes at concentrations as low as 100 ng per ml (5 ng per well in microtitre plates). Detection of anti-treponemal antibody was possible using rabbit syphilitic sera diluted to 1/10 000. The sensitivity of the assay was equal to or greater than that detected by radioimmunoprecipitation combined with gel electrophoresis and fluorography techniques and was capable of monitoring host IgG responses throughout the progress of the disease.