Serotyping and Genotyping of GenitalChlamydia trachomatisIsolates Reveal Variants of Serovars Ba, G, and J as Confirmed by omp1Nucleotide Sequence Analysis

ABSTRACTUrogenital isolates (n= 93) of Chlamydia trachomatiswere differentiated into serovars and variants by serotyping with monoclonal antibodies and genotyping by restriction fragment length polymorphism (RFLP) analysis of the PCR-amplifiedomp1gene, respectively. The types of 87 of the 93 isolates (94%) were identical, as determined by both methods. Among these 87 isolates, 3 isolates were identified as the recently described new serovariant Ga/IOL-238 by omp1nucleotide sequence analysis of the variable domains. Of the remaining six isolates, three isolates serotyped as both L2 and Ba but were identified as Ba/A-7 by genotyping by RFLP analysis of omp1. The omp1nucleotide sequences of variable domains VD1, VD2, and VD4 of these urogenital Ba strains were identical to the sequences of the variable domains of Ba/J160, an ocular Ba type. The three remaining isolates were serotyped as J, but the patterns obtained by RFLP analysis of omp1, which were identical for the three isolates, differed from that of prototype serovar J/UW36. omp1nucleotide sequence analysis revealed that these strains are genovariants of serovar J/UW36. Nucleotide sequence differences between serovar J/UW36 and this J genovariant, designated Jv, were found in both variable and constant domains. In conclusion, this study shows that the PCR-based genotyping of clinical C. trachomatisisolates by RFLP analysis ofomp1has a higher discriminatory power and is more convenient than serotyping. Variants of C. trachomatisserovars Ba, G, and J were identified and characterized.