The purification of rubella virus (RV) and determination of its polypeptide composition

Rubella virus (RV) has been propagated in murine fibroblasts (L cells) and purified using two Renografin gradients. The virus was grown in the presence of 2 μCi/ml ³H]uridine, pelleted from tissue culture media 6 days postinfection, and applied to a 25–45% discontinuous gradient. A single, sharp band was observed at the interface. This band was collected and applied to a 30–45% continuous gradient which separated intact labeled virions from ³H-labeled, light density material. Infectivity was measured using a modified hemadsorption assay. A recovery of 90% of the RV infectivity was achieved by these methods. Purified virions obtained in this way were dissociated, labeled with ¹²⁵I, immune precipitated with rubella-specific antiserum, and subjected to polyacrylamide slab gel electrophoresis and autoradiography. Four polypeptides were observed with molecular weights of 44, 41, 24, and 19 × 10³ designated as VP44, VP41, VP24, and VP19, respectively.