Accumulation of poliovirus proteins in uninfected isolated HEp-2 cell nuclei in vitro.

Poliovirus (type 1, Mahoney) proteins preferentially inhibited in vitro RNA polymerase II activity in uninfected isolated HEp-2 cell nuclei, as demonstrated by electron microscopic autoradiography. Structural integrity of the nuclei and preincubation of nuclei and poliovirus proteins in vitro prior to addition of [3H]-UTP were prerequisites for differential inhibition. During in vitro incubation, [3H]-labeled poliovirus proteins were shown to accumulate in the uninfected isolated nuclei. Similar poliovirus proteins accumulated in the nuclei to higher relative amounts as compared to the outside or were excluded from the nuclei after in vitro incubation, as in intact poliovirus-infected cells. Since the in vitro transcription system of isolated nuclei exhibited two characteristics of poliovirus infection, i.e., preferential inhibition of RNA polymerase II activity and accumulation of poliovirus proteins in the nuclei, it may be useful to study host RNA synthesis inhibition.