Genome comparison and phylogenetic analysis of orientia tsutsugamushi strains

Keisuke Nakayama, Ken Kurokawa, Masahiro Fukuhara, Hiroshi Urakami, Seigo Yamamoto, Kazuko Yamazaki, Yoshitoshi Ogura, Tadasuke Ooka, Tetsuya Hayashi

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)


Orientia tsutsugamushi (OT) is an obligate intracellular bacterium belonging to the family Rickettsiaceae and is the causative agent of scrub typhus, or Tsutsugamushi disease. The complete genome sequences of two OT strains (Boryong and Ikeda) have recently been determined. In the present study, we performed a fine genome sequence comparison of these strains. Our results indicate that although the core gene set of the family Rickettsiaceae is highly conserved between the two strains, a common set of repetitive sequences have been explosively amplified in both genomes. These amplified repetitive sequences have induced extensive genome shuffling and duplications and deletions of many genes. On the basis of the results of the genome sequence comparison, we selected 11 housekeeping genes and carried out multilocus sequence analysis of OT strains using the nucleotide sequences of these genes. This analysis revealed for the first time the phylogenetic relationships of representative OT strains. Furthermore, the results suggest the presence of an OT lineage with higher potential for virulence, which may explain the clinical and epidemiological differences between 'classic' and 'new' types of Tsutsugamushi disease in Japan.

Original languageEnglish
Pages (from-to)281-291
Number of pages11
JournalDNA Research
Issue number5
Publication statusPublished - Oct 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Genetics


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