An Active Interferon Inducer Obtained from <i>Hemophilus Influenzae</i> Type B

Abstract An extract was prepared from Hemophilus influenzae type b which induced significant interferon production both in vitro (human skin fibroblasts) and in vivo (mice). When compared to the endotoxin of Salmonella enteritidis the H. influenzae extract was 10 times more active in inducing interferon in human cells, 10,000 times more active in inducing cellular resistance to vesicular stomatitis virus in human cells and 300 to 1000 times less toxic in inducing lethality in mice and dermotoxicity in rabbits. The antiviral activity of the extract was not affected by ribonuclease, deoxyribonuclease or trypsin but was partially reduced by incubation at 25°C or 37°C. The chemical structure of the active substance of the H. influenzae extract has yet to be defined.