Isolation of Orientia tsutsugamushi from Leptotrombidium fuji and its characterization

In our attempts to isolate Orientia tsutsugamushi from trombiculid mites, a strain was successfully isolated from Leptotrombidium fuji collected in Ai chi Prefecture, Japan. This is the first case of isolation of O. tsutsugamu shi from L. fuji. A phylogenetic analysis based on the base-sequence homolo gy of the 56-kDa type-specific antigen-gene indicated that the strain is a new type which is not closely related to any strains analyzed previously. T hree strains isolated from Leptotrombidium pallidum harvested at the same a rea were identified as being closely related to the JP-2 type (subtype-2 of Karp type in Japan) by phylogenetic analysis.