Journal List > J Bacteriol Virol > v.46(4) > 1034233

Ha, Lee, Park, Cho, Kim, Ha, Cho, Hwang, Cho, Lee, Lee, Lee, Cho, Lee, and Shin: Isolation and Genetic Characterization of Orientia tsutsugamushi from Scrub Typhus Patients in Gyeongsangnam-do, Korea

Abstract

Orientia tsutsugamushi (O. tsutsugamushi), which is endemic to an Asia-Pacific region, has increased its incidence and caused annually around 10 thousand patients infected with scrub typhus in Korea in the past several years. In the present study, we isolated 44 O. tsutsugamushi from the patients with febrile illness accompanied with or without an eschar in Gyeongsangnam-do, Korea. These isolates were characterized by genetic analysis of the major outer membrane protein, the 56-kDa type-specific antigen (tsa56), which is unique to O. tsutsugamushi. Two types of sequences of tsa56, designated by JJ1 and JJ2, were determined from 37 and 7 isolates of the 44 isolates, respectively. JJ1 and JJ2 showed 74.7~90.8% identity in nucleotide sequence and 66.1~90.5% identity in amino acid sequence with 33 reference strains except for Boryong and Kuroki. JJ1 and JJ2 had 100 and 99.9% nucleotide identity to Boryong strain, and 99.9 and 99.8 % to Kuroki, which has been known to be similar to Boryong, respectively. In addition, they showed 77.9~ 81.4% nucleotide identity with the cluster of Gilliam-related genotypes, whereas they showed higher nucleotide identity (89.6~90.8%) with the cluster of Karp-related genotypes. To our knowledge, this is the first report to isolate O. tsutsugamushi and characterize their genotype as the Boryong in Jinju and West Gyeongsangnam-do, Korea, even though it has been reported that the Boryong was the predominant genotype in isolates from chiggers, domestic rodents, and patients in the southern part of Korea. Furthermore, our isolates could be useful source to study on the pathophysiology and epidemiology of scrub typhus in Korea.

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Figure 1.
The incidence of the scrub typhus patients of Gyeongsang National University Hospital in 2013 to 2015.
jbv-46-275f1.tif
Figure 2.
The PCR products of the 56-kDa type-specific antigen gene of O. tsutsugamushi from 15 representative isolates in the present study. Forty-four O. tsutsugamushi isolates were confirmed by tsa56-specific PCR assay, and PCR products of 15 representative isolates among 44 isolates were presented. M, DNA sizer marker.
jbv-46-275f2.tif
Figure 3.
Phylogenetic tree based on partial 56-kDa type specific antigen of O. tsutsugamushi. Two nucleotide sequences of O. tsutsugamushi isolates were analyzed phylogenetic relationship with reference sequences retrieved from the GenBank database as shown in Table 1. Solid triangle and diamond indicate two sequences of O. tsutsugamushi determined in this study.
jbv-46-275f3.tif
Table 1.
Sequence homologies of partial 56-kDa type specific antigen gene between Orientia tsutsugamushi strains
Isolates Nucleotide identity (%) Amino acid identity (%) Information
JJ1 JJ2 JJ1 JJ2 Source Country Year Accession no. Reference
Boryong 100 99.9 100 100 Human South Korea 1998 L04956 (9)
CB19 77.9 78.1 68.1 68.1 Rattus rattus Thailand 2009 GU068058 (13)
CB62 85.8 85.6 78.3 78.3 Bandicota indica Thailand 2009 GU068055 (13)
FPW2016 78.1 77.9 67 67 Human Thailand 2007 EF213085 (14)
Gilliam 86.5 86.4 78.3 78.3 Human Assam-Burma border 1943 DQ485289 (15)
Hirahata 90.8 90.7 90.5 90.5 Leptotrombidium pallidum Taiwan 1999 AF201835 (16)
Ikeda 81.2 81.1 72.3 72.3 Human Japan 1979 AF173033 (17)
Je-cheon 90.7 90.6 84.2 84.2 Human South Korea 2001 AF430143
Karp 90.6 90.5 84.6 84.6 Human New Guinea 1943 AY956315 (18)
Kato 76.9 76.8 66.1 66.1 Human Japan 1955 AY836148 (19)
Kawasaki 78.0 77.9 66.5 66.5 Human Japan 1981 M63383 (20)
Kuroki 99.9 99.8 100 100 Human Japan 1981 M63380 (21)
LA-1 90.0 89.9 82.8 82.8 Leptotrombidium arenicola Malaysia 1993 AF173049 (22)
LF-1 76.2 76.1 66.8 66.8 Leptotrombidium fletcheri Malaysia 1993 AF173050 (22)
Shimokoshi 74.8 74.7 61.4 61.4 Human Japan 1980 M63381 (17)
TA678 78.1 78.2 67 67 Rattus rattus Thailand 1963 U19904 (23)
TA686 82.0 82.1 73.1 73.1 Tupaia glis Thailand 1963 U80635 (23)
TA716 78.3 78.4 67.8 67.8 Menetes berdmorei Thailand 1963 U19905 (23)
TA763 84.1 84.2 74.6 74.6 Rattus rajah Taiwan 1963 U80636 (23)
Taitung-4 78.9 79.0 70.2 70.2 Taiwan 2004 AY787232
TW45R 90.7 90.6 84.2 84.2 Rattus losea Taiwan 2003 AY222632 (24)
TW461 81.1 81.0 71 71 Rattus rattus Taiwan 2003 AY222631 (24)
TWyu81 86.1 86.0 77.9 77.9 Leptotrombidium pallidum Thailand 2003 AY222640 (24)
UT76 85.9 85.8 71 71 Human Thailand 2007 EF213078 (14)
UT125 81.4 81.2 71 71 Human Thailand 2007 EF213096 (14)
UT144 81.4 81.2 78.3 78.3 Human Thailand 2007 EF213091 (14)
UT167 86.1 86.0 80.6 80.6 Human Thailand 2007 EF213080 (14)
UT176 89.8 89.6 80.6 80.6 Human Thailand 2007 EF213081 (14)
UT177 89.8 89.6 71 71 Human Thailand 2007 EF213084 (14)
UT196 81.4 81.2 86.3 86.3 Human Thailand 2007 EF213079 (14)
UT219 90.6 90.5 69.5 69.5 Human Thailand 2007 EF213100 (14)
UT302 79.4 79.6 78.3 78.3 Human Thailand 2007 EF213095 (14)
UT332 86.1 86.0 77.9 77.9 Human Thailand 2007 EF213083 (14)
Yeojoo 90.4 90.2 84.2 84.2 Human South Korea 2001 AF430144
Yonchon 81.2 81.1 72.1 72.1 Human South Korea 1989 U19903 (25)
Young-worl 87.8 87.7 79.4 79.4 Human South Korea 2001 AF430141

Original prototype strains

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