THE COMPLETE SEQUENCES OF AFRICAN HORSESICKNESS VIRUS SEROTYPE-4 (VACCINE STRAIN) RNA SEGMENT-2 AND SEGMENT-6 WHICH ENCODE OUTER CAPSID PROTEIN

The complete sequences of RNA segment 2 and segment 6 of African horse sickness virus serotype 4 (AHSV-4) vaccine strain were determined from cDNA clones inserted into pBR 322. The RNAs of segment 2 and 6 are 32 29, 1566 bp long respectively and both contain an open reading frame e ncoding proteins VP2 and VP5 of 1060, 505 amino acid residues. The est imated molecular weight of VP2 was 124,178 dalton and that of VP5 was 56,793 dalton. Their noncoding end sequences were 5'GTTTAA ... and ... ACATAC3' (segment 2), 5'GTTTAT ... and ... ACTTAC3' (segment 6). They were different from orbivirus characteristic terminal sequences, whic h were 5'GTTAAA ... and ... ACTTAC3'. The comparison of both sequences of AHSV-4 segment 2 and 6 with those of segment 2 and 5 of bluetongue virus (BTV) serotype 10 revealed 53% nucleotide similarity and 23% am ino acid similarity (segment 2), and 58% nucleotide similarity and 46% amino acid similarity (segment 6). In the same way, the comparison of both sequences of the vaccine strain with those of the virulent strai n segment 2 and segment 6 of AHSV-4 revealed 91 % nucleotide and 96% a mino acid similarity (segment 2), and 98% nucleotide and 98% amino aci d similarity (segment 6).