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Virulence in Mice of Orientia tsutsugamushi Isolated from Patients in a New Endemic Area in Japan
Author(s) -
Nagano Isao,
Kasuya Shiro,
Noda Nobuji,
Yamashita Teruo
Publication year - 1996
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1996.tb01135.x
Subject(s) - virulence , orientia tsutsugamushi , scrub typhus , biology , rickettsiosis , microbiology and biotechnology , strain (injury) , virology , infectious dose , rickettsiaceae , rickettsiales , rickettsia , bacteria , virus , gene , biochemistry , genetics , anatomy
Four strains of Orientia tsutsugamushi (KN‐1, KN‐2, KN‐3 and GJ‐1) isolated from patients in an area of Gifu Prefecture, Japan, in which tsutsugamushi disease is newly endemic, were examined for their virulence in mice. Among these, KN‐1 (identified as Kawasaki type), GJ‐1 (identified as Kuroki type) and KN‐2 strains were found to be non‐lethal for BALB/c mice as well as CH3/HeJ mice, even with high doses (10 6 × being the 50% mouse infectious dose). On the other hand, the KN‐3 strain was found to be sufficiently virulent to kill BALB/c mice. Among the prototype strains (Gilliam, Karp and Kato), the Karp and Kato strains exhibited high virulence to mice, while the Gilliam strain killed only a susceptible strain of mouse. BALB/c mice infected with KN‐1 and KN‐2 strains showed significant splenomegaly and moderate ascites accumulation in the first week of infection, while these symptoms became prominent during the second week of infection using KN‐3, Karp and Kato strains. After infection with the GJ‐1 strain, these symptoms were not observed. Antibody responses induced by infections with highly virulent strains were lower than that with low or intermediate virulent strains.