Immunochemical analysis of antigenic determinants of Chlamydia trachomatis by monoclonal antibodies

Monoclonal antibodies to outer membrane of Chlamydia trachomatis lymphogranuloma venereum (LGV) strain L1 (440-L) were used for antigen characterization. Two separate type-specific antigenic determinants (epitopes) and one species-specific epitope were represented in the major outer-membrane protein (MOMP, molecular weight 40 000) of homologous (440-L) and heterologous (IOL-1962, 810-B) L1 strains. One of the type-specific antibodies, the reactivity of which was not affected by oxidation or reduction of the antigenic sites, partially prevented the binding of species-specific antibody as determined by solid-phase radioimmunoassay. The binding of type- and species-specific antibody could be destroyed with proteolytic enzyme treatment. The reactivity of genus-specific monoclonal antibody originating from another fusion (L2, 434-Bu) was unaffected by proteolytic treatment but was sensitive to periodate, indicating the carbohydrate nature of the genus-specific epitope. Heating of antigens had no effect on the affinity of monoclonal antibodies studied.