Abstract: Objective To establish a field visual method for detecting the Orientia tsutsugamushi (Ot) in chigger mites using self-prepared dye-wax capsule kit on portable loop-mediated isothermal amplification (LAMP) device basis for developing a new field tool in control and prevention of scrub typhus.Methods The GroEL gene was selected as the target sequence,and the primer for LAMP detection was designed online.A recombinant plasmid rOt- GroEL was constructed as the positive control.SYBR Green I based dye-wax capsule kit was used to establish a close-tube visual LAMP targeting GroEL.Field visual detection was simulated and verified using portable LAMP device. Results A set of LAMP primers specific to the Ot GroEL gene was chosen to amplify the 237 bp target region. Sequencing results showed that the recombinant rOt-GroEL plasmid was successfully constructed.Detection limit of the plasmid was 1×102 copies using dye-wax capsule kit combined with portable LAMP device.Conclusion A close-tube visual LAMP method targeting Ot GroEL was established,which could be used for field visual detecting Ot in chigger mites with portable LAMP device.

Key words: Scrub typhus , Orientia tsutsugamushi , Chigger mite , Detection method , Portable LAMP device