Analysis of the human serological response to Chlamydia trachomatis 60-kDa proteins by two-dimensional electrophoresis and immunoblotting.

Earlier analyses of sera from humans and animals with chlamydial infections demonstrated a strong immune response to proteins of approximately 60 kDa. We have used two-dimensional (2D) electrophoresis followed by immunoblotting to more accurately define patient responses to the chlamydial 60-kDa cysteine-rich envelope protein (OMP2) and to the 57-kDa stress protein (SP) implicated in immunopathological damage. OMP2 and SP were separated on 2D gels by their distinct isoelectric points and identified by fluorography of [35S]-labelled proteins and cross-reaction with anti-mycobacterial antiserum, respectively. The majority of patients sera showed a strong reaction both to OMP2 and the SP (18/20 and 17/20 sera, respectively). Fewer sera (9/20 and 10/20 sera, respectively) reacted with two other polypeptides also present in the 60-kDa range by this analysis.