[Structure of the enzootic cattle leukosis virus. 1. Biophysicochemical characterization of several virus-specific...

Concentrated virus material partially purified, after having been obtained from permanent cell cultures, was allowed to undergo repeated gradient centrifugation for an analysis of density and sedimentation. Serological tests were conducted, in that context, together with electron microscopy and gel electrophoresis. Isodensities of the virion were 1.17 g/ml in CsCl solution or 1.16 g/ml in saccharose solution. The average densities of the internal bodies, between 45 nm and 80 nm in diameter, were measured by electron microscopy and accounted for something between 1.32 g/ml and 1.34 g/ml in CsCl solution or between 1.22 g/ml and 1.24 g/ml up to 1.28 g/ml in saccharose solution. Four revertase-positive components, 915 S, 704 S, 469 S and 264 S +/- 40 S, were found in flattened cane-sugar gradients. conclusions for non-invasive ultracentrifugation in the virus were drawn from those high S-values. High-titre mixed antigens, virus-specific bands from the density gradients, and washed antigen-antibody precipitates were investigated by the authors by means of slab-gel electrophoresis. Molecular weights of 53 kilodalton (kD) and 24 kD were recorded from the major components. There also were polypeptides weighing 10 kD, 12 kD, 15.6 kD, 42.5 kD, 63 kD, and 70 kD.