Alterations in initiation factor activity from poliovirus-infected HeLa cells.

Ribosomal salt washes were prepared from unin- fected and poliovirus-infected HeLa cells and separated by fractional (NHS the B fractions from both uninfected and infected cells were active with both cell and viral mRNA trans- lation. The uninfected ribosomal salt wash and the A and B fractions stimulated globin synthesis in a heter- ologous translation system dependent on exogeneous globin mRNA and all of the initiation factors. The ri- bosomal salt wash and the A fraction from infected HeLa cells were totally defective in this system. The inactivity of the infected cell fractions was not reversed by the further addition of active wash fractions from uninfected cells or purified reticulocyte initiation fac- tors. The HeLa ribosomal salt washes were fractionated by conventional techniques into fractions containing eIF3 and eIF4B activities. eIF4B activity was always detected in preparations from both infected and unin- fected cells. eIF3 activity was obtained from uninfected cells, but either was not present or was altered in preparations from infected cells. The results indicate that eIF4B probably was not the mRNA-discriminating factor, and suggest that either eIF3 or another factor which co-purifies with eIF3 may be responsible for the discrimination between cellular and viral mRNA trans- lation observed in infected cells. Poliovirus, like many animal viruses and bacteriophages, has long been recognized to interfere with host cell processes (1). In infected cells, poliovirus mRNA is preferentially trans- lated over host cell mRNA despite the fact that the cell mRNA appears to be unaffected during infection, both struc-