Detection of GLRaV-2 by ELISA using various antisera: Selected mouse antisera to native- (mice 1 and 3) and glutaraldehyde-treated GLRa V-2 (mice 5 and 8) and the monoclonal antibody were used to test the reaction of the antisera with extracts from various infected and virus-free grapevine cultivars. The grapevines were also tested by DAS-ELISA based on the rabbit antiserum to native virus. Results presented in Table 4 showed that mouse antisera to both native and glutaraldehyde-treated GLRaV-2 detected the virus with a high degree of sensitivity and specificity. Each mouse antiserum gave absorbance values below 0.02 for virus-free grapevines and was comparable with that of the monoclocal antibody. The sensitivity of detection of GLRaV-2 by DAS-ELISA based on the rabbit antiserum was much lower than that of the ATA-ELISA. The absorbance values for virus-infected grapevines in ATA-ELISA after 30 min of substrate incubation were only obtained in DAS-ELISA after more than 3 hours incubation. In spite of this, absorbance values for different GLRaV-2-free grapevine cultivars obtained in DAS-ELISA were lower than 0.065 (no visible colour reaction), and therefore this ELISA is still useful for detection of the virus.