SITE-SPECIFIC MUTATIONS IN THE NS2 PROTEIN OF EPIZOOTIC HEMORRHAGIC-DISEASE VIRUS MARKEDLY AFFECT THE FORMATION OF CYTOPLASMIC INCLUSION-BODIES

The importance of a conserved amino acid motif in the nonstructural pr otein NS2 of different orbiviruses was investigated with regard to vir us inclusion body (VIB) formation. A number of epizootic haemorrhagic disease virus NS2 deletion and substitution mutants were prepared and expressed as baculovirus recombinants. Deletion of the motif or substi tution of at least three residues within the region, had a detrimental effect on VIE formation in insect cells. Furthermore, these NS2 mutan ts were not complexed with single-stranded RNA in infected cells and a ppeared to be cytotoxic. Cumulatively, the results suggest that this m otif is an essential structural determinant for NS2 function.