The complete nucleotide sequence of bluetongue virus serotype 1 RNA3 and a comparison with other geographic serotypes from Australia, South Africa and the United States of America, and with other orbivirus isolates

The sequence of the RNA segment 3 of bluetongue virus (BTV) serotype 1 from Australia is presented along with its deduced amino acid sequence. DNA copies of this genome segment were inserted either into the E. coli plasmid pBR322 by homopolymeric tailing or by direct insertion of double-stranded DNA fragments generated by restriction endonuclease cleavage into the appropriate M13 bacteriophage vectors (Vieira, J. and Messing, J., 1982, Gene 19, 259-268). Direct comparisons were made to the nucleotide sequence data of Purdy, M. et al., 1984 (J. Virol. 51, 754-759) and Ghiasi, H. et al., 1985 (Virus Res. 3, 181-190) for the United States of America (US) isolates of BTV, serotypes 10 and 17, respectively. A method for the rapid cloning, sequencing and alignment of orbivirus RNA 3 segments was utilised to compare other geographical isolates of BTV, as well as those of other orbivirus serotypes, in particular, epizootic haemorrhagic disease of deer virus (EHDV) and Warrego. The comparison of this sequence data reveals that BTV isolates can be separated into distinct geographical types which in turn are distinct from the other orbivirus isolates studied. The sequence conservation at the amino acid level for the gene product of RNA3 (VP3) does not enable distinctions to be made amongst the BTV isolates at a geographical level, but does afford easy distinction into the different orbivirus groups. A possible evolutionary schematic is presented for the orbiviruses studied.