An Interferon-like Substance released from Tick-borne Encephalitis Virus-infected Chick Embryo Fibroblast Cells

Abstract

AN interference phenomenon between tick-borne encephalitis and Western equine encephalomyelitis viruses in chick embryo fibroblast monolayers has been described¹. When chick embryo tissue cultures are inoculated with tick-borne encephalitis virus, the virus multiplies readily, but no cytopathic effect appears until the sixth or seventh day of cultivation. If cultures thus infected had been superinfected with a convenient dose of Western equine encephalomyelitis virus, which normally completely destroys the cells within 48–72 hr., the following events could be observed : (1) complete degeneration of cells caused by this virus and, hence, no interference if tick-borne encephalitis virus-infected cultures were challenged with Western equine encephalomyelitis immediately or 24 hr. after primary inoculation; (2) partial interference if cultures were challenged 48 hr. after inoculating them with tick-borne encephalitis virus ; (3) complete suppression of the cytopathic effect caused by Western equine encephalomyelitis virus if challenged 72 hr. after primary inoculation. No interference was established if interfering virus previously neutralized by immune serum was added to cultures.