Cloning and Expression of a Surface Antigen of Orientia tsutsugamushi in E. coli

Scrub typhus or Tsutsugamushi Disease is an acuteand febrile disease caused by infection with Orientia(formerly Rickettsia) tsutsugamushi. This diseasecausing signifi cant health problem for military and civilianand is confi ned to a defi nite geographic region called‘tsutsugamushi triangle’. Larvae (chiggers) of trombiculidmites (Leptotrombidium) are vectors of scrub typhusfever transmitting the disease to human after a bite bythem. In this project, part of 110 kDa surface antigen ofO. tsutsugamushi was expressed by recombinant DNAmethod. The protein antigen coding sequence wasamplifi ed by PCR and ligated to pThioHis-B expressionvector and was expressed as a fusion to HisPatchthioredoxinin TOP 10 E. coli. The expressed fusion protein,which was overexpressed in 4.5 h after IPTG induction,was 61 kDa in size; in which 16 kDa was belonged to HPthioredoxin and 45 kDa was the antigenic polypeptides.The fusion protein could be used as a recombinant subunitvaccine for immunization against the O. tsutsugamushi.