New evidence for the precursor role of 14 S subunits in poliovirus morphogenesis.

In poliovirus-infected HeLa cells incubated as 30 degrees, 14 S subunits are selectively labeled and no virions are assembled. When the temperature is subsequently shifted to 37 degrees, the radioactivity of the 14 S material is transferred mainly to virions, showing that 14 S subunits are virion precursors. When 14 S subunits synthesized at 30 degrees are incubated in vitro at 37 degrees, they assemble to empty capsids.