Degradation of Poliovirus Polypeptides <Emphasis Type="Italic">in vivo</Emphasis>

CELLS infected with attenuated type 1 poliovirus (LSc) at 39° C synthesize only 20% of the viral proteins produced at 35° C. Polyacrylamide gel electrophoresis of viral peptides shows that only four peptides (with molecular weights of 230,000, 212,000, 196,000 and 160,000) are produced at the restrictive temperature¹. It was suggested that the last three are cleavage products of the 230,000 molecular weight peptide. Furthermore, since smaller peptides were never observed it was suggested that proteolysis might eliminate them from infected cells at 39° C. Nonsense and deletion mutations cause degradation of incomplete peptides of β-galactosidase² and the lac repressor³. We have studied whether there is significant proteolysis of the peptides of attenuated poliovirus in vivo at 39° C. There is extensive degradation of viral peptides at the restrictive temperature and essentially no degradation at the permissive temperature. The peptides of wild type virulent virus are not degraded at either 35° C or 39° C.