Double Strandedness of Ribonucleic Acid of Bovine Ephemeral Fever Virus

Abstract

Virus labeled with ³H-uridine or ³²P-orthophosphate was purified by CsCl equilibrium centrifugation of concentrated virus materials from infectious BHK21-WI2 cell culture fluids. A single clearly visible band formed in the gradient coinciding with a sharp peak of radioactivity having a buoyant density of 1.19g/ml. Infectisity exhibited a broader distribution with a peak coinciding kith the risible band, in which numerous virions of the sirus were observed with the aid of an electron microscope using the phosphotungstic negativc staining technique. Ribonucleic acid (RNA) extracted from the purified virus by the phenol method exhibited a rather broad distribution of radioactivity with a major peak at about 12S when analyzed by the sucrose density gradient centrifugation technique. Viral RNA centrifuged in the gradient after ribonuclcase (RNase) treatment showed a single sharp peak at about 12S These findings seemed to indicate that the virion of this virus contained double-stranded RNA. Double strandeclness of the viral RNA was further corroborated by an examination of the base composition, reduced resistance to RNase in low salt concentration and a sharp thermal transition with a relatively high melting temperature of 85C. The virus could not be classified either in the rhabdovirus group, although the shape of the vision resembled that of the rhabdoviruses, or in the reosirus group since the virus was ether-sensitive. It seemed necessars to create a new genus for this virus.