Isolation and Characterization of TR‐c, an Antigen of the Reiter Treponeme Precipitating with Antibodies in Syphilis

Abstract

TR-c is a Reiter treponemal antigen that cross-reacts with an antigen in Treponema pallidum (Nichols pathogenic strain). Sera from patients with secondary syphilis contain precipitating antibodies against TR-c. The isolation of TR-c from a crude bacterial sonicate involves 5 fractionation steps: anion exchange chromatography (DE-52 Whatman), gel filtration (Ac-A-22, Ultrogel) and affinity chromatography, respectively, on phenyl-Sepharose CL 4B iminodiacetic acid-Sepharose CL 4B, and lysine-Sepharose 4B. The purified TR-c was enriched 320 times compared with the starting material and the recovery was 22%. TR-c was shown to be a protein, it did not bind to a series of lectins, and by gel filtration and polyacrylamide gel electrophoresis (PAGE) the MW was determined to be 630,000-730,000. It was found by SDS[sodium dodecyl sulfate]-PAGE to be composed of identical subunits, each having a MW of 48,000. The isolated TR-c was immunochemically pure when tested in crossed immunoelectrophoresis against polyspecific anti-Reiter Ig. The purified TR-c antigen was used for production of a monospecific rabbit antiserum. Monospecific rabbit anti-TR-c gave strong fluorescence with both the Reiter treponeme and T. pallidum.