- Volume 40, Issue 1, 1978

An RNA polymerase activity has been demonstrated in purified rabies virions. Efficiency of the reaction is low since the rate of incorporation was equal to 3 to 5 pmol of uridine per hour, per mg of protein. As with other mammalian rhabdoviruses the optimal temperature was 31 °C. Unlike vesicular stomatitis virus, manganese could be substituted for magnesium as a divalent cation, at an optimum concentration of 10 to 20 mm.

The RNA components of two C-type RNA viruses, avian myeloblastosis virus and Friend leukaemia virus, have been isolated by treatment of the viruses with 6 m-guanidine-HCl and precipitation with ethanol. The virus proteins were recovered by lyophilization of the guanidine-HCl-ethanol supernatant after thorough dialysis against 0.5 mm-dithiothreitol. This simple method yielded RNA of similar quality to the phenol and sodium dodecyl sulphate (SDS) extraction methods, and the same amount of 60–70S RNA, although a fraction of the smaller (4S) species remained in the protein fraction. The sedimentation patterns of heat-denatured RNA extracted by either method were similar. Electrophoretic analyses of the extracted proteins in polyacrylamide gel gradients containing SDS gave patterns that were very similar to those obtained by direct analysis of SDS disrupted viruses.

A cell line resistant to ethidium bromide has been developed from baby hamster kidney cells transformed by Rous sarcoma virus. The parental cells are normally non-producers but the resistant cell line appears to produce virus-like particles that are associated with the mitochondria as visualized by electron microscopy and determined biochemically.

The antigen-antibody neutralization of filamentous phage Xf showed first-order kinetics within the first 10 minutes. Failure to reverse the neutralization reaction by dilution indicated that a stable combination might be formed between phage and antibody.

Antigenicity of Xf was analysed by agar double diffusion and three distinct precipitin lines were observed. For identifying these three antigenic components, Xf particles were dissolved and separated into A-protein and B-protein. The results of agar double diffusion showed that one precipitin line corresponds to the A-protein and the other two precipitin lines are determined by the B-protein.

3H-labelled 70S RNA of squirrel monkey retrovirus (SMRV) hybridized to a high degree (> 52%) to the DNA of various tissues of two squirrel monkeys. Hybridization of the same probe to DNAs of other primates including New World monkeys (Woolly monkey, capuchin, owl monkey), Old World monkeys (rhesus, African green), apes (gibbon, chimpanzee), and human (A204 cells infected with MPMV) revealed no significant hybridization. Analysis of the kinetics of hybridization indicated that SMRV provirus was present in multiple copies in various squirrel monkey tissues ( = 120 to 400) and in SMRV-infected A204 cells at a low number of copies ( = 1500). These results demonstrate that SMRV is an endogenous virus of squirrel monkeys and the first isolated from a New World monkey.