A single-stranded ribonucleic acid(s) has been isolated from purified virions of visna virus. It consists of two major components, namely 63S and "4S," under the conditions employed for ribonucleic acid (RNA) extraction. The 63S component can be converted to subunits by heat and dimethylsulfoxide treatments. Analyses by base composition indicate that the "4S" RNA isolated from visna virus is no...

days against EDTA. Assuming a molecular weight for the virus of 50 x 106, calculation of the number of atoms of iron, copper, calcium, and magnesium per virus particle gave values of 20, 3, 52, and 45, respectively. The fact that iron and magnesium were concentrated approximately 20-fold in the virus ribonucleic acid compared with the occurrence of about 5 percent nucleic acid in the virus indi...