ANTIGENIC AND MOLECULAR ANALYSES OF DIFFERENT CHLAMYDIA-PNEUMONIAE STRAINS

Chlamydia pneumoniae is an important human respiratory pathogen. Class ification of C. pneumoniae isolates into distinguishable serovars or g enotypes has not yet been reported. To determine whether antigenic or molecular variants among C. pneumoniae isolates exist, six strains wer e studied via immunoblot analysis and DNA sequence determination of th e entire major outer membrane protein (MOMP) gene omp1. The strains in cluded four prototype strains and two clinical isolates from our labor atory, Immunoblot analysis of sera from patients infected with C. pneu moniae revealed antigenic differences between the C. pneumoniae strain s, Strong reactivity of one serum sample with a 65-kDa protein in two C. pneumoniae strains which was not observed with the other strains wa s the most prominent finding, All sera reacted with the 40-kDa MOMP. C omparison of the omp1 DNA sequences revealed that the omp1 genes of al l strains were identical and were 100% identical to the sequence of th e omp1 gene of C. pneumoniae AR-39, The results of this study demonstr ate that unlike C. trachomatis, the omp1 gene is conserved in C. pneum oniae, Furthermore, it was shown that C. pneumoniae strains are antige nically different. This finding indicates that more than one serovar o f C. pneumoniae exist.