The rickettsial outer-membrane protein A and B genes of Rickettsia australis, the most divergent rickettsia of the spotted fever group.

The genes for rickettsial outer-membrane protein A (rOmpA), a distinguishing feature of spotted fever group (SFG) rickettsiae, and rOmpB, a genus-specific protein, were identified and sequenced in Rickettsia australis. The amino acid sequences of domains I, III and IV of the R. australis rOmpA share close homology with those of rOmpA of other SFG rickettsiae, but the repeat region (domain II) is dramatically different from that of other known SFG rOmpA. R. australis rOmpB is more similar to rOmpB of other SFG rickettsiae than to that of typhus group rickettsiae.