BTV-8 or GIV infected BHK-21 cells (5610 6 cells) and BTV-8 infected KC cells (5610 6 cells) were dissolved for 10 min at 100uC in 1 ml of sample denaturation buffer (160 mM Tris-HCl, 4 mM EDTA, 3.6% SDS, 60 mM DTT, 0.2% ß-mercaptoethanol, 0.8% methionine, 800 mM sucrose). A volume of 20 ml was analysed per well, by electrophoresis in a minigel (Miniprotean III tank -Bio-Rad). Purified and pelleted virus particles were also dissolved in sample buffer and analysed by SDS-PAGE, using a 4-20% gradient polyacrylamide gel.