INTERFERON-LIKE VIRAL INHIBITOR IN RABBITS AFTER INTRAVENOUS ADMINISTRATION OF ENDOTOXIN.

Intravenous injection into rabbits of endotoxin or killed cells of Escherichia coli induced, in 1 hour, a viral inhibitor detectable in serum. The inhibitor disappeared from the serum in 7 to 24 hours, and was only active after incubation with rabbit cell cultures. Like interferon, it did not preferentially inactivate virus directly, was ineffective in chick cells, was inactivated by trypsin, and was not sedimentable. Unlike interferon, the inhibitor was heat labile. Nucleic acid or nucleotides apparently play no role in its induction.