Abstract:
The culture fluid of chorioallantoic membrane (CAM)pieces exposed to ultraviolet irradiated avirulent strain of Ranikhet disease virus has been found to contain a factor which interferes with the multiplication of Ranikhet disease and vaccinia viruses. Maximum interference activity is found in the fluid collectedn at 48 hr. The activity of the fluid does not decrease when treated with RNAase or on dialysis, and the active substance could be precipitated with acetone. Virus interference factor is also produced in the nutrient fluids of CAM cultures, allantoic fluids of chick embryos, and liver and lung extracts of fowls infected with avirulent strain of Ranikhet disease virus. The extracts of the liver and lungs collected at 72 hr Show maximum virus interference activttv. Though at 72 hr of infection the sera and the tissue extracts of the fowls do not show virus neutralizing property, the fowls are resistant to a lethal dose of a virulent strain of the virus.
