Phylogenetic Analysis of 56-kDa Type-Specific Antigen Gene of Orientia tsutsugamushi Isolates in Taiwan

Abstract

Scrub typhus is a rickettsial disease transmitted to humans through the bite of chigger mites infected with Orientia tsutsugamushi, and is an endemic disease in Taiwan. To elucidate the molecular epidemiology of O. tsutsugamushi, the complete open reading frame of the 56-kDa type-specific antigen gene sequence of strains isolated from scrub typhus patients were determined and analyzed. A total of 116 isolates of O. tsutsugamushi were successfully isolated from patients infected in diverse geographic origins including Taiwan and three offshore islets, Kinmen, Matsu, and Penghu between May 2006 and December 2007. Sequence analysis revealed that 22 distinct sequence types could be identified that were broadly distributed in different clusters of the phylogenetic tree. Most of the isolates belong to Karp, Kawasaki, and Kuroki genotypes and are closely related to strains from Thailand, Japan, and Korea, whereas unique isolates different from other countries were also found in Taiwan. Distinct seasonal distributions were found in different sequence types. Some sequence types caused disease in the cold season, whereas others caused disease in the warm season.

Genetic Typing, Based on the 56-Kilodalton Type-Specific Antigen Gene, of Orientia tsutsugamushi Strains Isolated from Chiggers Collected from Wild-Caught Rodents in Taiwan

“…Consistently, a large number of isolates belonged to the TA763 clade, a strain type commonly present in Thailand but not in Japan and Korea. It is noteworthy that the 56-kDa TSA gene sequences detected in this study were closely related to those found in a previous study of blood samples from Taiwan scrub typhus patients (15), suggesting the pathogenic potential of O. tsutsugamushi strains. The results are shown in Table 2, indicating that among Kato-related strains, KM-06, KM21-1 OI-09, and TT01-1 were 99% or more identical to the TW-22 strain.…”

New Genotypes of Orientia tsutsugamushi Isolated from Humans in Eastern Taiwan

“…Previously, Tamura et al described six prototype genotype strains: Karp, Kato, Kuroki, Kawasaki, Gilliam and Shimokoshi [3], [10], [11], [12], [13], [17]. Six different Taiwanese genotyping isolates were also characterized by RFLP analysis by Taiwan CDC in 1999: Taiwan-A, -B, -C, -D, -E and -F [21].…”

Scrub typhus in South India: clinical and laboratory manifestations, genetic variability, and outcome

“…A recent phylogenetic analysis of O. tsutsugamushi from Taiwan reported two unique sequence types along with Karp-related, Saitama, JG-related, and Kuroki-related genotypes. 12 Multi-locus sequence typing (MLST) analysis of Thai isolates has shown a very high rate of recombination, which along with gene duplication and horizontal transfer accounts for the genetic diversity among O. tsutsugamushi isolates. 13,14 In 2008, five O. tsutsugamushi clades were reported to be circulating in Cambodia and three in Vietnam, with high genetic diversity.…”