[Possible role of translation initiation factors in the regulation of expression of attenuated mutations of poliovirus].

Initiation of poliovirus RNA translation in reticulocyte lysates is mainly not precise, i.e. it occurs at the sites in the middle of the viral genome but not at the beginning of the polyprotein reading frame. The anomaly is due to the deficiency of translation initiation factors. Partial purification of the protein fraction stimulating the precise translation from the Krebs-2 cells is reported in the paper. This fraction, like the crude lysates factors, was considerably less active with the RNA of attenuated poliovirus strains of type 1 and 3 than with the RNA of virulent strains. The change in interaction of the specific segment of viral RNA with the translation initiation factors is suggested to contribute to the attenuated phenotype of the Sabin poliovirus strains.