Comparison of the nonstructural protein, NS3, of tick-borne and insect-borne orbiviruses.

The complete nucleotide sequence of the smallest RNA segment (segment 10) of Broadhaven (BRD) virus, a tick-borne orbivirus, was determined from a full-length cDNA clone. The genome segment is 702 nucleotides in length and has a coding capacity for two proteins of either 205 or 199 amino acids, having net charges of +16.5 and +17.5, respectively, at neutral pH. Comparison of the sequence of RNA segment 10 of BRD, bluetongue, African horse sickness, and Palyam viruses revealed amino acid homology of 20 to 30% between the four orbiviruses, with one conserved region of 40 to 50% homology which, in segment 10 of BRD virus, is found between residues 26 and 71.