FIG. 4.

Human antibody recognition of chlamydial GST fusion and endogenous antigens. Antibodies in the pooled human sera were immobilized onto protein G- and protein A-agarose beads, and the bead complexes were used to react with chlamydial antigens in either C. trachomatis serovar D-infected HeLa cell lysates (lane 1) or bacterial lysates (lane 2) containing GST-CPAF (a), GST-HSP60 (b), or GST-MOMP (c). The bead-bound antigens were loaded onto an SDS-polyacrylamide gel for Western blot detection with specific antibodies to CPAF (MAb 100a) (a), HSP60 (MAb BC7.1) (b), or MOMP (mouse antiserum) (c). As antigen loading controls, the bacterial (lane 3) and chlamydia-infected HeLa (lane 4) lysates (without prior precipitation) were directly loaded onto the parallel gel wells. Note that the human sera efficiently precipitated both GST fusion and endogenous chlamydial proteins. DF, degradation fragments; i.p., immunoprecipitation; +, present; −, absent.