Comparative sequence analysis of a genus-common rickettsial antigen gene.

The genes encoding the 17-kilodalton genus-common antigen have been cloned and sequenced from Rickettsia conorii, Rickettsia prowazekii, and Rickettsia typhi. Compared with the R. rickettsii sequence, this sequence had a high degree of homology within the coding and control regions (R. conorii, 99.8%; R. prowazekii, 88.1%; R. typhi, 88.7%). The 5' flanking regions, including the promoter and the transcription initiation sites, were extremely well conserved for all four species, suggesting that control and expression of this locus are important to the survival of the rickettsiae.