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POSTERS: Pathogen detection, quantification and diagnosis

Comparison of newly developed ELISA and RT-PCR assays for the detection of all known genetically diverse variants of GLRaV-3
Alfredo Diaz-Lara - University of California-Davis. Adib Rowhani- University of California, Minsook Hwang- University of California, Kristian Stevens- Department of Evolution and Ecology, University of California-Davis, Maher Al Rwahnih- University of California-Davis, Vicki Klaassen- Foundation Plant Serv

Grapevine leafroll-associated virus 3 (GLRaV-3) is the main etiological agent of grapevine leafroll disease, one of the most important virus diseases of grapevine worldwide. The long-distance spread of GLRaV-3, caused by the movement of infected vines, can be controlled effectively if GLRaV-3 is accurately identified and clean stock is made available to growers. However, the development of reliable detection assays is complicated by the high genetic diversity of GLRaV-3. Phylogenetic studies based on whole genome sequences have placed GLRaV-3 isolates into ten different genetic groups. Additionally, new divergent variants have been discovered recently around the world. To cover this genetic diversity, we developed new enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase quantitative PCR (RT-qPCR) assays for GLRaV-3 detection. These assays were tested using a large number of geographically diverse grapevine samples that included plants infected with different GLRaV-3 variants. Both assays detected all known GLRaV-3 variants characterized to date and represent two new alternatives for high throughput sample testing that are both sensitive and specific for GLRaV-3. In the case of the ELISA, this assay brings the advantage that reagents are relatively cheap and no special equipment is needed. These new detection tools will benefit growers, researchers, and diagnostic labs involved in the grapevine industry in the US and around the world.