We conducted this study to describe the phylogenetic analysis of the 56-kDa type-specific antigen (TSA) gene of Orientia tsutsugamushi associated with PCR positive cases of scrub typhus.
Co-existence of multiple O. tsutsugamushi strains within infected mites has previously been reported in naturally infected, laboratory-reared mite lines using molecular methods to characterize the 56-kDa type-specific antigen (TSA) gene.
The region of the 56-kDa TSA gene spanning from variable domain I (VDI) to variable domain IV (VDIV) was sequenced and used for genotyping 77 O. tsutsugamushi samples from human patients confirmed with scrub typhus from 2001 to 2003 and 2009 to 2010 in different regions of Thailand.
The 56-kDa type specific antigen (TSA) gene, encoding the major antigenic protein, was used as reference to investigate the genetic relationships between the strains and to genotype O. tsutsugamushi isolates.