Rapid detection of tilapia lake virus using a one-step reverse transcription loop-mediated isothermal amplification assay

Tilapia lake virus (TiLV) is a newly emerging viral disease in tilapia with recent outbreaks in many parts of the world. There is an urgent need to develop an accurate, sensitive, on-farm method for rapid detection of TiLV to limit economic loss and prevent the spread of the virus into new geographical areas. In this study, we developed a rapid, one-step reverse transcription, loop-mediated, isothermal amplification (RT-LAMP) method for the detection of TiLV in fish tissues. Our results revealed that the RT-LAMP assay was able to detect TiLV infection in infected cell culture materials, and fish samples collected from different geographic locations in Thailand. In total, 166 tissue samples were collected from TiLV-infected fish and uninfected fish from tilapia farms in Thailand with a history of TiLV outbreaks, and fish showing clinical signs of TiLV infection were tested using our RT-LAMP protocol. The RT-LAMP assay offered high specificity and sensitivity compared to reverse transcription polymerase chain reaction (RT-qPCR) assay. These results supported the application of the RT-LAMP assay for the diagnosis of TiLV with benefits including reduced analysis time and easy interpretation of results based on the colorimetric change, thus offering a diagnostic tool in resource-limited countries where there is an urgent need for rapid diagnostic assay to guide TiLV control.