BOVINE EPIZOOTIC FEVER .2. PHYSICOCHEMICAL PROPERTIES OF VIRUS

It was found that the ruins of Bovine Epizootic Fever appeared to be RNA as its replication was not inhibited by 5‐iodo‐2′‐deoxyuridine. It had a buoyant density of 1.196, was not filterable through membrane filter (Millipore Filter Corp. Mass.) of 100 mμ pore size, and was sensitive to ether, chloroform and deoxycholate, was inactivated by trypsin and ultraviolet irradiation, precipitated by protamine sulfate, readily inactivated at pH 3.0, fairly labile at 56 C but readily preserved at —80 C, not stabilized at 50 C by I M MgCl2, and resisted repeated freeze‐thawing. The virus appears not to require a DNA‐depcndent RNA synthesis in the host cell for its replication, as chromomycin A3 did not inhibit its replication. Sucrose density gradient centrifugation was unsuitable for purification because of a very poor recovery of infectivity. CsCl equilibrium density gradient centrifugation was successfully used for this purpose, and electron microscopy of the resulting fractions by phosphotungstic negative staining technique revealed virus‐like bullet‐shape particles, about 140 mμ in length and 80 mμ across, in the fraction of peak infectivity titer. The particle is probably the virion of the virus. These findings suggest relation of the virus to Rhabdoviruses [6], but further studies are necessary. The physicochemical properties of the virus provide additional evidence for similarity of the virus to bovine ephemeral fever virus, and emphasizes the desirability of further detailed comparative studies to decide whether they are one and the same or merely very closely related. © jointly owned by Japanese society for Bacteriology and Society of Japanese Virologists