Specific amplification of Rickettsia japonica DNA from clinical specimens by PCR.

The gene encoding the 17,000-molecular-weight genus-common antigen (17K genus-common antigen) has been cloned and sequenced from Rickettsia japonica. The primer pair used for PCR was designed from this sequence. A 357-bp fragment was observed by amplifying the genomic DNA from R. japonica and also the DNA from blood clots of patients with spotted fever group rickettsiosis. The results indicated that this method is suitable for the diagnosis of spotted fever group rickettsiosis in Japan.