DIFFERENTIATION OF RICKETTSIA-JAPONICA BY RESTRICTION-ENDONUCLEASE FRAGMENT LENGTH POLYMORPHISM USING PRODUCTS OF POLYMERASE CHAIN-REACTIONAMPLIFICATION WITH RICKETTSIA-RICKETTSII 190-KILODALTON SURFACE-ANTIGEN GENE PRIMERS

Restriction fragment length polymorphism of polymerase chain reaction (PCR) amplification products differentiated Rickettsia japonica, a cau sative agent of Oriental spotted fever, from other spotted fever group (SFG) rickettsiae. Primer pair Rr190. 70p and Rr190. 602n of R. ricke ttsii 190-kDa antigen gene sequence primed genomic DNAs obtained from R. japonica, type strain YH and strains NT, NK, YKI, and TKN. The prod ucts were cleaved by PstI but not by AfaI restriction endonuclease. Th e PstI digestion pattern of PCR-products amplified from all strains of R. japonica was identical and easily differentiated from that of othe r SFG rickettsiae. The present study demonstrated a genotypic differen ce between R. japonica and other pathogenic SFG rickettsiae.