Identification of Japanese isolates of spotted fever group rickettsiae

Research Project

Project/Area Number	63044102
Research Category	Grant-in-Aid for Overseas Scientific Research
Allocation Type	Single-year Grants
Section	Joint Research
Research Institution	University of Tokushima
Principal Investigator	UCHIDA Takahiro University of Tokushima School of Medicine, 医学部, 教授 (60045325)
Co-Investigator(Kenkyū-buntansha)	YU Xuejie University of Texas Medical Branch at Galveston, 医学部, 研究員 DAVID H. Wal 米国テキサス大学, 医学部, 教授 UCHIYAMA Tsuneo University of Tokushima School of Medicine, 医学部, 助手 (90151901) WALKER David H. University of Texas Medical Branch at Galveston
Project Period (FY)	1988
Project Status	Completed (Fiscal Year 1988)
Budget Amount *help	¥4,000,000 (Direct Cost: ¥4,000,000) Fiscal Year 1988: ¥4,000,000 (Direct Cost: ¥4,000,000)
Keywords	Sptted Fever Group Rickettsia / Rickettsia japonica / Spotted Fever / リケッチア感染症
Research Abstract	Spotted fever group (SFG) rickettsiae isolated from patients in the southeastern part of Shikoku, Japan, were analyzed to identify the species by use of mouse antisera. Antigenic differences between five strains of Japanese isolates and standard strains of pathogenic SFG rickettsiae were examined by calculating the specificity difference (SPD). the SPD between each pair of Japanese strains showed their antigenic identity, while the SPD between Japanese strains and pathogenic standard strains of SFG indicated that Japanese strains are clearly distinct from R.akari, R.australis, R.conorii, R.rickettsii, and R.sibirica. It was also demonstrated that Japanese strains are different from Thai tick typhus rickettsia (strain TT-118) isolated from a tick, known only in the Orient. Monoclonal antibody analysis resulted in no cross-reaction between Japanese strain and standard strains but positive reactions of Japanese strains with monoclonal antibody to Japanese strain. Comparison of the Japanese strain and standard strains of SFG rickettsiae by Western immunoblotting with mouse antiserum to Japanese strain demonstrated that the Japanese strain are distinct from any of the standard strain of SFG rickettsiae. The results obtained in this study demonstrated that the Japanese isolates of SFG rickettsiae belong to a single species distinct from any SFG rickettsiae known to be pathogenic to humans. We proposed the taxonomic name Rickettsia japonica sp. nov. pertaining to Japan, since that is the country in which it was first isolated.