Synthesis of murine leukemia virus in cell culture

Using high resolution, electron microscopic autoradiography, the times for macromolecular synthesis and assembly of a murine leukemia virus were determined. The time between completion of viral, RNA and protein synthesis and the appearance of morphologically complete virions did not exceed 30 min. The sequence of cellular labeling following exposure to 3H-uridine was: nucleolar; nuclear; cytoplasmic. Labelling kinetics for viral RNA paralleled that for cytoplasmic RNA and coincided with a decrease in grain counts over nucleolar areas. Comparison of labelling kinetics for type-A and -C virions supports the idea the type-A virions are precursors for type-C.