Elimination of Grapevine rupestris stem pitting-associated virus (GRSPaV) from two Vitis vinifera cultivars by in vitro chemotherapy

The grapevine (Vitis vinifera L.) cultivars 'Agiorgitiko' and 'Malagouzia', naturally infected with Grapevine rupestris stem pitting-associated virus (GRSPaV), were subjected to in vitro chemotherapy using the antiviral inosine 5'-monophosphate dehydrogenase inhibitors tiazofurin (TR), ribavirin (RBV) and mycophenolic acid (MPA). The chemotherapy lasted 80 days and was carried out as two consecutive treatments. Severe phytotoxicity, estimated after 40 days of culture, was observed in drug-treated explants, especially when high doses of TR were used. Phytotoxicity exhibited a cultivar- and chemical compound-dependent profile. The virus eradication status of the survived plantlets was determined by nested RT-PCR using total RNA templates, after 80 days of drug treatment and one year later, after the passage of one dormancy period, in potted plants grown in a greenhouse. Data indicated that the highest GRSPaV elimination in 'Agiorgitiko' was obtained with 10 mu g ml(-1) TR, 30 mu g ml(-1) RBV and 20 mu g ml(-1) MPA. The eradication rates were lower in the case of 'Malagouzia', where the highest ones were achieved after treatments with 15 mu g ml(-1) TR and 80 mu g ml(-1) MPA. This is the first report on GRSPaV elimination in grapevine following treatment with antiviral compounds, which could provide an alternative to the traditional methods of virus eradication through meristem culture and thermotherapy.