DNAse I is an endodeoxyribonuclease that can degrade dsDNA into 59 phosphorylated tetranucleotides [28] . A dsDNA ladder (Promega) with sizes ranging from 2645 to 36 bp provides a target for DNAse I cleavage. Competition assays between DNAse I (Roche) and BTV-8 or GIV NS4, were carried out in a final volume of 20 ml, containing 2 ml of 10X DNAse I buffer and 2 mg of dsDNA. The reaction was incubated at room temperature for 20 minutes, followed by addition of a 2 U of DNAse I, then incubated for a further 30 minutes at 37uC. The completed reaction was heated at 99uC for 1 minute to inactivate the DNase and the reaction products were analysed by 2% agarose gel electrophoresis.