Evaluation of Detection Methods for Cymbidium Mosaic Virus

Cymbidium mosaic virus (CymMV) and odontoglossum ringspot virus (ORSV) are the two most important orchid viruses worldwide.  A common and convenient method for detecting these viruses is the lateral flow immunoassay test.  Lateral flow immunoassay tests are reliable and sensitive for virus detection, carry approximately the same cost as reverse-transcription followed by PCR (RT-PCR) and are complete in less than 30 minutes.  Additionally, growers can complete these tests in the field without expensive lab equipment.  However, orchid growers in Hawaii report that lateral flow immunoassay tests from different manufacturers sometimes yield contradictory results when detecting CymMV.  For example, one plant tested positive for CymMV using a Glift test kit and negative using an Agdia ImmunoStrip test.  This plant was subsequently tested for the presence of CymMV using RT-PCR using primers designed to amplify the CymMV coat protein gene. A DNA amplicon was produced from that reaction, but was approximately 400 base pairs smaller than expected.  Further, during a survey of orchid hybrids we found 9 plants that tested positive for CymMV using the Agdia orchid ImmunoStrip test and tested negative for CymMV using RT-PCR (three primer pairs for different regions of the CymMV genome).  While infection with ORSV was common, there were no discrepancies between ORSV test methods., We are working towards resolving the discrepancies between the CymMV detection methods.