Characterization of Spotted Fever Group Rickettsia in Ticks Collected from South Korea

Recently, numbers of newly emerging spotted fever group Rickettsia spp. wereobserved in ticks. Here, we explored to determine the prevalence of rickettsiaspecies found in ticks from 2 northeastern provinces (Gyeonggi, and Gangwon)of South Korea. A total of 1,798 Ixodid ticks were collected by tick drag methodsfrom August to September 2009 in two northeastern provinces. 204 sampleswere screened for the rickettsial 17-kDa antigen gene using nested PCR (nPCR),and 25 samples showed positivity. Of the 25 samples, 16 (64%), 11 (44%), and9 (36%) were positive for rickettsial outer membrane protein A (ompA) gene,outer membrane protein B (ompB) gene, and surface cell antigen 4 (sca4) gene,respectively. BLAST results of ompB, ompA and sca4 sequences were obtainedfrom the two identified genotypes designated as Rickettsia sp. str. koreansis,formerly named as HlR/D91, (from Haemaphysalis longicornis) and InR/D372 (fromIxodes nipponensis). The ompA small part (645bp) of Rickettsia sp. str. koreansisshared 99.8% similarity with Rickettsia sp. FuJ98 (firstly identified in China) whileompA large part (1651bp) of Rickettsia sp. str. koreansis showed 98.8% similaritywith R. heilongjiangensis. Further, ompB (1848bp) and sca4 (1705bp) of Rickettsiasp. str. koreansis showed 97.9% and 97.6% sequence similarities with R. hulinensisand R. japonica, respectively, while ompA (small & large parts), ompB, and sca4derived from Rickettsia sp. InR/D372 clustered with R. monacensis (99.8%) andR. tamurae (99.6%), respectively. These data suggest that the potentially newRickettsia sp. str. koreansis was closely related to R. japonica, R. heilongjiangensisin northeastern Korea. KCI Citation Count: 0