Abstract
Injection of mice with mouse brain suspensions of lymphocytic choriomeningitis virus produced a non-specific virus inhibitor which required 48 to 72 hr to act in monkey kidney and HeLa cell cultures. Like interferon it was active against numerous RNA viruses, was non-sedimentable, was unaffected by antiserum to lymphocytic choriomeningitis virus, and showed a doseresponse effect. However, unlike interferon it was acid-labile, crossed species barriers, and was eliminated by changing the medium at the time of virus challenge. Mouse brain preparations freed of detectable virus by ultracentrifugation had properties similar to preparations containing lymphocytic choriomeningitis virus. Furthermore, tissue culture fluids containing lymphocytic choriomeningitis virus contained no inhibitor. Tissues of mice infected with the WE strain of lymphocytic choriomeningitis virus also contained no inhibitor. Hence, this inhibitor appears to represent a new class of broad spectrum virus inhibitor that may be useful for the characterization of lymphocytic choriomeningitis virus strains.