Structural difference between the 5' termini of viral and cellular mRNA in poliovirus-infected cells: possible basis for the inhibition of host protein synthesis.

Host protein synthesis in poliovirus-infected HeLa cells is interrupted, but the host mRNA appears to remain completely intact and unmodified. The average size and poly (A) content of host mRNA was previously known to be unchanged (Koschel, 1974; Leibowitz and Penman, 1971), and this was confirmed. In addition, the 5' terminal methylated "cap" structures remained intact, and no further base modifications at the level of 1 base in 1,000 could be detected. Poliovirus RNA from viruses was previously shown not to have "caps" (Wimmer, 1972), and in this work poliovirus RNA from polyribosomes was found to have pUp at its 5' end. Since, initiation of protein synthesis is probably the basis for the inhibition of cellular protein synthesis in infected cells, the difference in the 5' ends of the host cell and viral RNA could be the basis of selective translation of viral RNA during infection.