THE MAJOR OUTER-MEMBRANE PROTEIN OF A SINGLE CHLAMYDIA-TRACHOMATIS SEROVAR CAN POSSESS MORE THAN ONE SEROVAR-SPECIFIC EPITOPE

The major outer membrane proteins (MOMPs) of human Chlamydia trachomat is serovars exhibit four regions of variable amino acid sequences (VS1 to VS4) harboring serovar-specific B-cell epitopes. Antibody response s to these epitopes mag contribute to acquired protection against huma n chlamydial infection. MOMP B-cell epitopes defined by 22 different s erovar-specific or bispecific murine monoclonal antibodies were locali zed with synthetic peptides representing the four VS regions of seven genital serovars (D, Da, E, F, G, H, and K). Serovar F possessed two d istinct serovar-specific epitopes, located in VS2 and VS4, while serov ar K possessed three distinct serovar-specific epitopes, located in VS 1, VS2, and VS4. Serovar D- and serovar Da-specific epitopes were loca ted in VSI, servoar E- and serovar G-specific epitopes were located in VS2, and serovar H-specific epitopes were located in VS1. Regardless of whether the serovar was from the B (serovars D, Da, and E), C (sero vars H and K), or F-G (serovars F and G) serogroup, all serovar-specif ic epitopes were found in three discrete subregions of MOMPs. These su bregions comprised the central portion of VS1, residues 70 to 77; the amino-terminal half of VS2, residues 139 to 149; and the carboxyl-term inal third of VS4, residues 305 to 315. Monoclonal antibodies to each of these subregions neutralized infectivity in standard HaK cell cultu re assays. These findings are relevant to the development of an MOMP o r MOMP subunit vaccine.