Protection of Mice by Interferon Against Systemic Virus Infections

Abstract

Mice were protected against intraperitoneal infection with encephalomyo-carditis virus (EMC) and Semliki Forest virus (SF) by subcutaneous or intramuscular inoculation of mouse interferon. Protection was shown by an increase in the number of mice surviving infection or as an increase in the mean period of survival after infection. Large amounts of interferon (3000-5000 units, as measured in vitro) were required to protect a mouse under the conditions of these experiments. Better results were obtained when the interferon was injected by the intramuscular route. A single dose of interferon afforded protection to mice when injected at times between 30 and 3 1/2 hours before injection with virus, but not when given 48 hours before infection. Some protection was obtained when a large dose of interferon was given three hours after injection.