Determination of genome size and restriction fragment length polymorphism of four Chinese rickettsial isolates by pulsed-field gel electrophoresis.

Pulsed-field gel electrophoresis (PFGE) was used to determine the genome size and the restriction fragment length polymorphism (RFLP) of four new Chinese isolates of spotted fever group (SFG) rickettsiae. The genome size of the isolates Ha-91, BJ-90, 054 and 036 was 1,253 kb, 1,236 kb, 1,272 kb, and 1,272 kb, respectively. The isolates 054 and 036 had identical RFLP profiles. All the isolates differed in the properties under study from the so far known SFG rickettsiae. The unique RFLP profiles of the isolates supported our opinion that they are new strains of SFG rickettsiae or even new species of SFG rickettsiae.