The role of cytoplasmic membranes in poliovirus biosynthesis

Abstract

Chemical analysis and electron microscopy show that isopycnic centrifugation in discontinuous sucrose density gradients separates smooth and rough cytoplasmic membranes of HeLa cells. By 3.25 hours after poliovirus infection, there is evidence of marked proliferation of cytoplasmic membranes in the smooth microsomal fraction. Sixty-five percent of labeled virus-specific RNA is found in this fraction after a 2.5-min pulse of uridine-³H 3.25 hours after infection; however, after a 10-min pulse, most of the labeled RNA is found in the rough microsomal fraction. Over 50% of newly synthesized viral protein is found in the rough microsomal fraction throughout a 30-min chase period following a 3-min pulse of leucine-³H. This pattern of distribution of viral RNA and protein is dependent on the presence of cytoplasmic membranes. The major site of translation of viral RNA is associated with rough membranes, whereas replication of viral RNA takes place in association with smooth membranes. Results after addition of guanidine to infected cells support the hypothesis that viral RNA synthesis is initiated in a complex associated with smooth membranes.