Phylogenetic Analysis of the 56 kDa Protein Genes of Orientia tsutsugamushi in Southwest Area of Korea

This study was conducted to determine which genotypes were present in southwestern Korea. Nested polymerase chain reaction (PCR) and DNA sequence analysis targeting the Orientia tsutsugamushi-specific 56-kDa protein gene was performed with samples of blood and eschar. Of the 69 PCR-positive samples, 61 clustered with the Boryong previously isolated in Korea. CUH 4-6 had sequence homology of 100% with Kato, and CUH 4-3 had homology of 99.8% with Kato and formed the Kato cluster. CUH 4-57, CUH 4-31, CUH 4-142, and CUH 4-324 formed a Kawasaki cluster. CUH 4-271 had sequence homology of 100% with Jecheon and formed a Karp cluster. CUH 4-117 had homology of 99.8% with Neimeng-65, and Gilliam cluster. The most common genotype of O. tsutsugamushi in the southwestern part of Korea is the Boryong genotype. We also identified O. tsutsugamushi of the Kato, Neimeng-65 and Kawasaki genotypes, which had not been identified before in Korea.