Antigenic structure of surface-exposed regions of the major outer-membrane protein of Chlamydia trachomatis.

The major outer-membrane protein (MOMP) of Chlamydia trachomatis displays a number of surface-exposed epitopes. Some of these are shared by all or some of the 15 known serovars, whereas others are serovar-specific. With use of epitope-mapping analysis of limited proteolytic digests of purified MOMPs with monoclonal antibodies, the present study assessed whether the same or different surface-exposed regions of the protein express these different epitopes. Results with both chymotrypsin and the staphylococcal V8 protease for MOMP of serovar F indicated that many of the shared surface epitopes are clustered in one region whereas the serovar-reactive epitope is located in a separate region. Analysis of MOMPs from all the serovars with a species-specific monoclonal antibody indicated that each MOMP possesses a structurally analogous region that expresses this epitope. Such a region might play a role in pathogenic mechanisms that are shared by all serovars.