Detection of White Spot Syndrome Virus by Polymerase Chain Reaction Performed Under Insulated Isothermal Conditions

Aiming to develop a rapid, low-cost, and user-friendly system for the diagnosis of white spot syndrome virus (WSSV), a PCR assay performed in capillary tubes under insulated isothermal conditions (iiPCR assay) was established on the basis of Rayleigh-Benard convection. WSSV amplicons were generated reproducibly within 30 min from a target sequence-containing plasmid in an iiPCR device, in which a special polycarbonate capillary tube (R-tube™) was heated isothermally by a copper ring attached to its bottom and shielded by a thermal baffle around its upper half. Furthermore, WSSV-specific amplicons were produced from nucleic acid extracts of WSSV-infected Penaeus vannamei in the WSSV iiPCR assay, with sensitivity comparable to that of an OIE-certified commercial nested PCR kit (IQ2000™ WSSV Detection and Prevention System). Specificity of the WSSV iiPCR assay was demonstrated as no amplicons were generated from shrimp genomic DNA, and IHHNV, MBV, and HPV DNA. iiPCR has a potential as a low-cost method for sensitive, specific and rapid detection of pathogens.