GEOGRAPHICAL GENETIC-VARIATION IN THE GENE ENCODING VP3 FROM THE ALBERTA ISOLATE OF EPIZOOTIC HEMORRHAGIC-DISEASE VIRUS

The complete nucleic acid and deduced amino acid sequences of gene seg ment 3 and the encoded VP3 from the North American, Alberta isolate of epizootic hemorrhagic disease virus serotype 2 (EHDV-2) are reported. Complementary DNA corresponding to segment 3 was 2768 nucleotides in length with an open reading frame of 2697 base pairs which encoded a V P3 polypeptide of 899 amino acid residues. Sequence comparison with ge nome segment 3 and VP3 from the Australian strain of EHDV-2 indicated genotypic and phenotypic homologies of 79% and 94%, respectively. Two North American field isolates of EHDV-2, as well as EHDV-1 (New Jersey isolate), had virtually identical homology to the Alberta isolate. Se quence analysis delineated North American EHDV strains as members of a genetically homologous and geographically distinct group of orbivirus es (topotype). The data support the hypothesis that geographic isolati on between North American and Australian orbiviruses has permitted the viral topotypes to maintain their genetic distinctness.