Inhibition of transcription factor activity by poliovirus.

To study the poliovirus-induced inhibition of host-cell RNA synthesis, we prepared transcription extracts from mock-infected and poliovirus-infected HeLa cells. In contrast with the control extracts, poliovirus-infected cell extracts prepared 3 hr after infection were unable to transcribe specifically DNA templates recognized by RNA polymerase II. Accurate transcription by RNA polymerase III, however, was only slightly reduced. Supplementation of the infected cell extract with a crude preparation of transcription factors (S100) restored its ability to transcribe a polymerase II template specifically; supplementation with purified polymerase II had no effect. When the S100 was fractionated on a phosphocellulose column, the restoration activity eluted between 0.35 M and 1 M KCl. When we tested infected extracts for inhibitory activity by mixing uninfected and infected cell extracts, no in vitro inhibition of polymerase II transcription by the uninfected extract was evident. These results indicate that at least one factor required for specific transcription by polymerase II is deficient in extracts from poliovirus-infected cells.