Cloning and sequence analysis of genomic fragment encoding 190KD protein antigen of HL-93 spotted fever group Rickettsiae

Genomic fragment encoding 190kD protein antigen was amplified from spotted fever group (SFG) rickettsiae HL-93 strain by polymerase chain reaction with a pair of primers Rr 190. 70p and Rr 190. 602n which were designed from DNA sequences encoding 190kD protein antigen of R. rickettsii and cloned into E. coli JM101 by using plasmid vector PGEM-T. The genomic fragment was sequenced and compared with that of R. rickettsii and R. japonica which were reported previously. The results showed that 31 and 24 nucleotides in HL-93 strain differed from that in R. rickettsii and R. japonica, respectively. The genetic homology was 94% and 95. 5% respectively, and amino acid homology was 87% and 89% respectively. All data suggest that HL-93 strain is a new member of SFG rickettsiae.