The complete sequence of African horsesickness virus serotype 4 (vaccine strain) RNA segment 5 and its predicted polypeptide compared with NS1 of bluetongue virus

The complete sequence of RNA segment 5 of the African horsesickness virus serotype 4 (AHSV-4) vaccine strain was determined from cDNA clones inserted into pBR322. The RNA is 1751 bp long (M(r) 1.12 x 10⁶) and contains an open reading frame encoding a protein of 548 amino acids (M(r) 63122) with a net charge of +0.5 at neutral pH. A comparison of the sequence of AHSV-4 segment 5 with that of segment 6 of bluetongue virus (BTV) serotypes 10 and 17 revealed 49.2% and 48.9% nucleotide similarity, respectively, and 31.4% amino acid similarity. However, AHSV-4 segment 5 has no significant similarity to BTV segment 5. In addition, Northern blot hybridization showed that full-length AHSV-4 segment 5 cDNA cross-hybridized with the corresponding genes of all serotypes of attenuated AHSV.