“…Both viruses contain RNA, resist treatment with lipid solvents (Gomatos, Tamm, Dales & Franklin, 1962) and are trypsin sensitive (Gomatos & Tamm, 1962;Mayor & Jordan, 1965). Of interest in this context are results by Polson & Deeks (1963) indicating that African horse sickness virus, another serologically unclassified, RNA-containing and ether-resistant arbovirus, which also is unstable below pH 6 and transmitted by Culicoides spp., has an ultrastructure which closely resemblea that of reoviruses (Vasques & Tournier, 1962;Jordan & Mayor, 1962 buffer. Below pH 6 bluetongue was irreversibly inactivated within 1 min.…”