Tissue blot immunoassay and direct RT-PCR of cucumoviruses and potyviruses from the same NitroPure nitrocellulose membrane.

A method is described for using Nitropure nitrocellulose (NPN) membranes as an effective solid matrix for retrieval of template RNA of three potyviruses, Tobacco etch virus, Soybean mosaic virus and Turnip mosaic virus, and two cucumoviruses, Cucumber mosaic virus and Peanut stunt virus. These NPN membranes were also used for tissue blot immunosorbent assays (TBIAs) to identify and detect plant viruses. For RNA detection, discs from dried membranes blotted with infected tissue were minimally cleaned with Triton X-100 and placed directly into reverse transcription (RT) reactions to initiate cDNA synthesis. Aliquots of cDNA plus primers specific for coat protein produced PCR amplicons of expected sizes for each of the viruses. Intensity of PCR-amplified bands from cDNA transcribed from both non-processed and TBIA-processed NPN membranes was comparable to those using FTA Card protocols. Direct sequencing of PCR products yielded high quality runs enabling identification to species. NPN membranes retained immunologically detectable virus particles, as well as intact template viral RNA, for more than a year at room temperature. The quantity of amplification product decreased after several months of storage, but could be increased by increasing the number of PCR cycles.