Effect of Streptovitacin A on Replication of an RNA Virus (Poliovirus). ∗

Summary

Streptovitacin A, a highly efficient inhibitor of protein synthesis, at 10 μg/ml of medium completely prevented synthesis of infectious poliovirus (type 1) and of CF antigen, as well as of CPE, in BS-C-1 cells when it was added up to about an hour before the end of the eclipse phase and was then left in the medium for the duration of the experiment. When the drug was added at the very end of the eclipse period, before new infectious virus had appeared, and was then left in the medium, a small amount of new virus appeared in the cells. When the drug was added during the exponential phase of viral multiplication, there was always some further increase in infectious virus but never at the level achieved in the untreated cultures. When the drug was added one or two hours after infection and washed away one or two hours later, the subsequent delay in viral synthesis was always considerably longer than the time the drug was present in the culture medium. These results fit the assumption that protein synthesis in BS-C-1 cells is not completely inhibited for 15-30 minutes after the addition of the drug and is not restored for a number of hours after its removal, as was found by Dales for L cells. The data also indicate that the drug-induced interference with protein synthesis during any phase of the poliovirus replication cycle did not result in an irreversible progression in the synthesis of infectious virus.