Purification of a Chlamydia trachomatis-specific antigen by immunoadsorption with monospecific antibody

This study describes the isolation and partial characterization of a Chlamydia trachomatis specific antigen. A species-specific antigen of C. trachomatis (antigen-0.65) was identified by two-dimensional immunoelectrophoresis. Antiserum specific for antigen-0.65 was prepared in rabbits by immunizing with agarose-gel precipitates excised from two-dimensional immunoelectrophorograms. Purified gamma-globulins from antigen-0.65 specific serum were coupled to the N-hydroxysuccinimide ester derivative of agarose which was then used for the immunoadsorbent purification of antigen-0.65 from Triton X-100 solubilized lymphogranuloma venereum (L2/434/Bu) organisms. The isolated antigen was immunochemically pure when tested against rabbit antiserum prepared to LGV-434 organisms by using rocket and two-dimensional immunoelectrophoresis. Antigenicity was destroyed by protease treatment and heating at 56 degrees C for 30 min, but the antigen was stable to ribonuclease, deoxyribonuclease, periodate oxidation and pH extremes of 2.2 and 10.6. Polyacrylamide gel electrophoresis of purified antigen showed a major protein band with an apparent m.w. of 155,000.