The inhibition of rabies virus by arabinosyl cytosine. Studies on the mechanism and specificity of action

In vitro studies on Borna virus. II. Properties of the virus

Successful cultivation and titration of Borna disease virus in cell cultures enabled detailed studies of the virus properties. Borna virus is labile towards treatment with heat, pH 3.0 and lipid solvents. It is relatively stable at low temperatures and in frozen state. It is easily inactivated by ultraviolet light as e.g. vesicular stomatitis virus. After ultrafiltration studies, the size of the infectious virus unit is between 80 and 100 nm. Its buoyant density in cesium chloride is 1.165 g per ml. The one step multiplication curve shows that Borna virus has a replication cycle of about 2 days in BSC 1 cells. In growth experiments using antimetabilites it behaves like certain RNA containing viruses. As its multiplication is not inhibited by bromo- and iododeoxyuridine and actinomycin D, no DNA step seems to be involved in virus synthesis. Regarding these properties and the intracellular antigen distribution as shown by fluorescent antibodies, it is not possible to attribute Borna virus to any of the established virus groups.

Rhabdovirus replication in enucleated host cells

Infection of enucleated TC-7 monkey cells with rabies virus resulted in the synthesis of virus-directed RNA and the production of rabies antigens but not of infectious virus. The yield of infectious vesicular stomatitis virus from enucleated TC-7 cells, on the other hand, was almost as high as that from intact cells. Inhibition of the mitochondrial functions of enucleated cells by treatment with ethidium bromide did not influence the development of rabies antigens or the production of infectious vesicular stomatitis virus.

Density gradient centrifugation studies on lymphocytic choriomeningitis virus and on viral ribonucleic acid

Lymphocytic choriomeningitis (LCM) virus, Traub strain, was purified from BHK-21 tissue culture medium. The virus was then analyzed by equilibrium centrifugation and rate zonal centrifugation in sucrose gradients. A buoyant density in sucrose of 1.18 g/ml was found and the S(20, w) value was estimated to be about 470 to 500S. Furthermore, the (3)H-uridine-labeled ribonucleic acid (RNA) from virus was extracted from LCM virus and analyzed by rate zonal centrifugation. Two major and one minor single-stranded RNA components were found with sedimentation coefficients of 28, 22, and 18S.