In vitro assembly of polioviruses. 3. Assembly of 14 S particles into empty capsids by poliovirus-infected HeLa cell membranes

Rough membranes obtained from poliovirus-infected HeLa cells have the capacity to assemble 14 S particles into 73 S empty capsids in vitro. A corresponding fraction from uninfected cells did not possess this activity. When labeled 14 S particles were incubated with smooth membranes obtained from infected cells, a significant amount of radioactivity sedimented as heterogeneous material in the 30–70 S region of the gradient.Sucrose gradient analysis of ¹⁴C-labeled rough and smooth membrane fractions lysed with deoxycholate (DOC) demonstrated the presence of 14 S particles, 73 S empty capsids, and a 110 S structure in the rough membrane fraction. These structures were found only in trace amounts in the smooth membrane fraction. In the absence of DOC treatment, no 14 S particles were found in any of the membrane fractions. The 73 S empty capsids, on the other hand, were detected in the presence or absence of DOC treatment in the rough-membrane fraction. Therefore, it appears that 14 S particles are associated with the rough membranes where they are assembled into 73 S empty capsids and/or complete virions.