Isolation of a type-specific antigen from Chlamydia trachomatis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

This report describes the isolation of a type-specific antigen of a serotype A strain of Chlamydia trachomatis. The antigen could be identified in sodium dodecyl sulfate-polyacrylamide electrophoretic (SDS-PAGE) analysis of immunoprecipitates of homologously reacted lysates from Bolton-Hunter 125I-labeled elementary bodies, solubilized by sonication and treatment with Nonidet P40. The electrophoretic pattern of this precipitate revealed a peak of unique mobility that was not reproduced by heterologous or control precipitates. Immunoadsorbtion of test antigen with purified IgG fractions from homologous antisera completely removed this peak, whereas similar adsorbtion wth heterologous IgG had minimal effect. Comparison of this antigen in SDS-PAGE with protein standards revealed an approximate m.w. of 27,000.