PHYLOGENETIC RELATIONSHIP OF CHLAMYDIA-PNEUMONIAE TO CHLAMYDIA-PSITTACI AND CHLAMYDIA-TRACHOMATIS AS DETERMINED BY ANALYSIS OF 16S-RIBOSOMAL DNA-SEQUENCES

The 16S ribosomal DNA sequence of Chlamydia pneumoniae was determined and compared with the corresponding gene sequences of Chlamydia psitta ci and Chlamydia trachomatis. C. pneumoniae has been reported to exhib it little chromosomal DNA homology with the other chlamydial species, and its phylogenetic relationships within the genus Chlamydia have not been described. A polymerase chain reaction was employed to determine the 16S rRNA gene sequence of C pneumoniae. Ten primers from the C. p sittaci sequences were used to amplify a C. pneumoniae template in ove rlapping segments of the gene. Sequence data for 1,554 bases indicated that the levels of homology of C. pneumoniae with C. psittaci and C. trachomatis were 96.19 and 94.07%, respectively. These data support th e results of previous biochemical and developmental studies indicating that C. pneumoniae is more closely related to C. psittaci than to C. trachomatis.