Issue link: http://read.dmtmag.com/i/81015
VINEYARD When testing for Virus Detecting on your Vines By Judit Monis, Ph.D. ach season, thousands of samples are submitted to laboratories to determine whether viruses are present that affect the quality of grapes for wine production. Vineyard professionals wonder why testing results are different when similar samples are submitted to different laboratories. This should not be shocking: Testing methodologies vary from laboratory to laboratory, as do the interpretation of results. LAB TESTING METHODS Two methods are standard for the detection of grape- vine viruses in a commercial testing setting: ELISA and RT-PCR. ELISA stands for "enzyme-linked immuno-sor- bent assay" and RT-PCR is short for "reverse transcrip- tion-polymerase chain reaction." ELISA uses antibodies that bind directly with the virus of interest affixed onto a test plate. After the virus binds, an enzymatic reaction occurs that will develop color in the test well if the sample is positive. ELISA has 74 VINEYARD & WINERY MANAGEMENT SEPT - OCT 2012 AT A GLANCE Testing methodologies and results interpretations vary from laboratory to laboratory. The sensitivity of TaqMan and RT-PCR are similar when known virus-infected samples are tested. The genetic specificity of TaqMan can be a disadvantage, as it can miss detection of viruses with slight changes (or mutations) in grapevine viruses. Two complementary testing methods are recommended for test results assurance. WWW.VWM-ONLINE.COM grapevine viruses such as leafroll disease, different methods can produce varying results. A comparison of modern laboratory methods and technologies a broad virus detection capability; however, it is limited to the amount of virus present in the test sample. For example, the virus concentration in the vine sample could be weak due to seasonality, and therefore not be detected. Additionally, ELISA reagents are more dif-