EXTENT AND KINETICS OF GENETIC CHANGE IN THE OMP1 GENE OF CHLAMYDIA-TRACHOMATIS IN 2 VILLAGES WITH ENDEMIC TRACHOMA

Variants of Chlamydia trachomatis in two Gambian villages with hyperen demic trachoma were analyzed by omp1-based polymerase chain reaction a nd sequencing from conjunctival swabs. Samples collected over a 22-mon th period included a complete cross-sectional study of each village. O verall, 4 genovar A and 4 B variants were characterized by point mutat ions in the omp1 gene, resulting in changes in the inferred amino acid sequence. Two genovar A and 2 B variants accounted for 87% of the tot al ocular chlamydial infection in both villages. Although some flux in the prevalence of individual variants was observed over time, their o verall distribution remained remarkable stable. There was no evidence of major antigenic shift arising from recombination events at the omp1 locus as described for genital tract infection. These results indicat e that omp1 variation in these two trachoma-hyperendemic communities i s limited and unlikely to hamper development of trachoma vaccines base d on the major outer membrane protein.