The ability of GIV NS4 to protect dsRNA from cleavage by endoribonucleases of the RNAse III family and its ability to bind dsRNA agree with sequence analyses that indicated the presence of a dsRNA binding domain in GIV NS4 [18] . The inability of BTV NS4 to protect dsRNA from cleavage by endoribonucleases of the RNAse III family and its inability to bind dsRNA in a platebased colorimetric assay are in agreement with sequence analyses that failed to detect a dsRNA binding domain in its aa sequence [18] . Other reoviruses dsRNA-binding proteins include Sigma 3 of mammalian orthoreovirus (found in both the cytoplasm and nucleus), and pns10 of rice dwarf virus [54, 55] .