Initiation factor preparations from poliovirus-infected cells restrict translation in reticulocyte lysates

Abstract

The translation of poliovirus RNA and vesicular stomatitis virus (VSV) mRNAs was studied in reticulocyte lysates supplemented with uninfected HeLa cell or polio-infected HeLa cell ribosomal salt wash as a source of initiation factors. Ribosomal salt wash from uninfected HeLa cells supported translation of both RNAs. Similar preparations from polio-infected HeLa cells stimulated translation of polio RNA; however, the translation of VSV mRNAs was completely restricted. Lysates programmed simultaneously with polio RNA and VSV mRNA translated both RNAs, although VSV translation was predominant. Addition of polio-infected cell ribosomal salt wash resulted in translation of polio RNA exclusively. The infected cell salt wash did not prevent formation of 40 S·Met-tRNA f Met complexes, but did prevent binding of labeled VSV mRNA to 40 S initiation complexes. The ability to restrict VSV mRNA translation resided in the 40% ammonium sulfate fractional precipitate prepared from infected cell salt wash. Similar fractionation of ribosomal salt wash mixed with labeled poliovirus double-stranded RNA indicated that this component was also found in the 40% ammonium sulfate fraction. The effects on translation of double-stranded RNA and the restrictive activity of infected cell salt wash were compared: mRNA specificity, kinetics of inhibition, nuclease sensitivity, and relief of inhibition by excess double-stranded RNA differed. From these comparisons, the possibility that double-stranded RNA caused the restriction of VSV mRNA translation was excluded.