Prolonged Antiviral Protection by Interferon Inducers

SummarySeveral interferon inducers including bacteria, viruses, and synthetic polycarboxylates demonstrated an antiviral effect against vaccinia virus challenge in mice. Various extracts of living materials were equally effective in stimulating interferon production. They provided rather transient protection in contrast with the prolonged protection following injection of either living microorganisms or plastics. The antiviral activity offered by injection of these different interferon inducers 1 day before virus challenge can be explained by interferon production. The protection observed at later times might or might not be mediated by interferon, but seems to depend on the continuous presence of the microorganisms or plastics in the host.The technical assistance of Mrs. L. Reghers-Aelvoet is gratefully acknowledged.