Development of immunocapture reverse transcription loop-mediated isothermal amplification assays to detect both lily symptomless virus and cucumber mosaic virus

Lily symptomless virus (LSV) and cucumber mosaic virus (CMV) are two of the most prevalent viruses that infect lily plants around the world. Infections of the edible Lanzhou lily (Lilium davidii var. unicolor) by these viruses seriously decrease crop yield in northwestern China. Development of reliable, practical and sensitive diagnostic tools is essential for surveillance and management of the viruses. Here we describe the development of immunocapture (IC) reverse transcription (RT) loop-mediated isothermal amplification (LAMP) assays for detecting both viruses. This approach captures viral antigens using antibodies (anti-rabbit IgG) against recombinant LSV or CMV coat proteins and then detects them by means of RT-LAMP, without needing to isolate RNA. Optimal conditions for both LAMP reactions were 60 degrees C for 60 min. The detection limit of both assays was 100 times more sensitive than the IC-RT-polymerase chain reaction assay. The IC-RT-LAMP assay results are also visible to the naked eye using SYBR Green dye. This is the first study to report the detection of LSV and CMV in lily using an IC-RT-LAMP assay. We believe that this convenient and sensitive method has excellent potential for enhanced diagnosis of field-collected samples, especially where laboratory facilities and technical resources are limited or absent.