Further Observations on the Inhibitory Action of Ammonium Chloride on Influenza Virus. ∗

Abstract

Summary

The effect of NH₄Cl on viral penetration was measured in chorioallantoic tissue in vitro by neutralizing absorbed virus with antiserum and determining the subsequent 24 hour yield of hemagglutinins. In some experiments conditions for single cycle replication were obtained by leaving the antibody in the supernatant during the entire period of growth and then measuring cell-associated hemagglutinins. Although some reduction of the amount of penetrated virus was demonstrable one hour after adding virus and NH₄Cl this later became insignificant. The prevention of viral penetration by NH₄Cl was considered too inefficient and irregular to account for the over-all inhibitory effect of NH₄Cl on viral replication. Inhibition by NH₄Cl of a type B (Lee) strain was comparable with that for Type A and reversibility of inhibition was demonstrated.