Anti-GLRaV-3 coat protein polyclonal antibody

The complete genome sequences of two newly identified genetic variants of grapevine leafroll-associated virus 3 (GLRaV-3) are described. Two isolates, GH11 (18671 nt) and GH30 (18576 nt) were sequenced and found to be less than 70 % similar to other South African GLRaV-3 variants. The genome organization of GH11 and GH30 is similar to that of previously described GLRaV-3 isolates. However, no corresponding open reading frame 2 (ORF2) could be identified. Phylogenetic analysis indicates that GH11 and GH30 cluster in a subgroup (group VI) that is separate from the previously described GLRaV-3 isolates and should be regarded as a different strain of GLRaV-3.

Vineyard surveys were conducted for three consecutive seasons in eastern Washington State, the major grapevine-growing region in the state, to document the occurrence of Grapevine leafroll-associated virus 3 (GLRaV-3) and Grapevine red blotch virus (GRBV). The majority of samples were collected from red-berried wine grape (Vitis vinifera) cultivars exhibiting symptoms of or suspected for grapevine leafroll (GLD) and red blotch (GRBD) diseases. A limited number of samples from white-berried cultivars were collected randomly due to the lack of visual symptoms. Samples were collected from a total of 2,063 grapevines from 18 red-berried cultivars and seven white-berried cultivars planted in eight American Viticultural Areas and tested for GLRaV-3 and GRBV using RT-PCR and PCR, respectively. The results showed 67.77% and 6.01% of total samples positive for GLRaV-3 and GRBV, respectively, and 9.06% of samples positive for both viruses. About 17% of samples tested negative for the two viruses, but some of these samples were positive for GLRaV-2 and GLRaV-4. Overall results indicated that GLRaV-3 was more common than GRBV, independent of cultivars and the geographic origin of samples. Due to variability in symptoms in red-berried cultivars, virus-specific diagnostic assays were deemed necessary for reliable identification of GLRaV-3 and GRBV and to differentiate GLD and GRBD symptoms from those induced by biotic and abiotic stresses in vineyards. A multiplex PCR protocol was developed for simultaneous detection of GLRaV-3 and GRBV in grapevine samples. A global phylogenetic analysis of GRBV genome sequences revealed segregation of virus isolates from Washington State vineyards into two distinct Glades, with the majority of isolates belonging to Glade II.