Development of a reverse transcription loop-mediated isothermal amplification assay for the rapid detection of Pepper mottle virus

Pepper mottle virus (PepMoV) is a widespread threat to vegetable crop production in the USA and south-east Asia. We describe the development of a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay to detect PepMoV. The RT-LAMP assay was based on a set of four primers that match a specific region of the coat protein gene in the PepMoV genome. The detection limit of conventional RT-PCR detection was 1.47 x 10(-4) mu g mu L-1 of cDNA, whereas RT-LAMP was 10 times more sensitive. Using RT-LAMP, PepMoV detection was also highly specific, showing no cross-activity with four other potyviruses. Sixty-nine field samples collected from symptomatic pepper plants growing in five South China provinces were tested for the presence of PepMoV infection by performing an RT-LAMP assay as well as a conventional RT-PCR. Both methods detected PepMoV in 18 samples, demonstrating that the PepMoV-specific RT-LAMP assay could be a useful alternative tool for the diagnosis and epidemiological surveillance of PepMoV infections. The RT-LAMP assay also has the advantages that it can be performed in a low-tech environment and is quicker and cheaper to perform than conventional RT-PCR.