Development and evaluation of a real-time reverse transcription-loop-mediated isothermal amplification assay for rapid serotyping of foot-and-mouth disease virus.

A one-step, real-time reverse transcription-loop-mediated isothermal amplification assay (RT-LAMP) for rapid detection and serotyping of Indian foot-and-mouth disease virus (FMDV) is described. The RT-LAMP assay was found to be 10(3)-10(5) fold more sensitive in comparison with RT-PCR, with a detection limit ranging from 10(-3) to 10(-5) TCID(50) of virus samples of all three serotypes. The RT-LAMP assay and qRT-PCR could detect 100 percent of clinical samples of three serotypes, whereas the RT-PCR detected 69.7% of type O, 58.1% of type A and 60.0% of Asia 1 samples. The qRT-PCR has the same sensitivity as the RT-LAMP. The assay conditions with absence of cross reactivity within the three serotypes of FMDV and FMDV negative samples were established. The RT-LAMP assay could detect 100% of samples stored in FTA(®) cards. In comparison with the performance of the RT-PCR; the RT-LAMP appears to be more sensitive, rapid and specific, with the potential for use as a point-of-care (POC) test, especially in developing countries. The use of FTA(®) cards for the preservation of RNA samples coupled with the RT-LAMP assay for the identification of serotypes may help in achieving improved FMDV serotype identification both in the field and in the laboratory.