Evaluation of a loop-mediated isothermal amplification assay for rapid diagnosis of soft-shelled turtle iridovirus

Softshelled turtle iridovirus (STIV) is the first Asian iridovirus isolated from reptiles, which infects soft-shelled turtles severely and leads to "Red neck disease" associated with high mortality. A set of four specific primers was designed by targeting the STIV Thymidine kinase (TK) gene and amplified STIV DNA specifically under optimized amplification conditions at 63°C for 60 min. The sensitivity of the loop-mediated isothermal amplification (LAMP) assay was found to be 20 copies/μl of STIV DNA. To evaluate the application of the LAMP assay for detection of STIV in clinical samples, 223 samples suspected of STIV infection from turtle tissues were tested by the LAMP assay and by cell-based virus isolation. A 78.5% concordance was observed between the results of the two methods. In this study, a robust and simple LAMP assay for rapid detection of STIV was developed and evaluated, which is the first suitable for potential diagnosis and helping to monitor STIV infections in the aquaculture industry.