THE MATURATION OF WESTERN EQUINE ENCEPHALOMYELITIS VIRUS AND ITS RELEASE FROM CHICK EMBRYO CELLS IN SUSPENSION

Abstract

Experiments are presented in which the plaque assay technique was used to study the intracellular appearance and release of Western equine encephalomyelitis virus in suspensions of infected chick embryo fibroblasts. Cells were artificially disrupted, releasing intracellular virus, by ultrasonic vibration. No intracellular virus could be found during the 1st hour after adsorption in spite of the fact that more than 104 cells per ml proved to be infected by later releasing virus. This indicates the virus loses its infectivity upon entering a susceptible cell. The 1st progeny virus was detectable within the cells between 1 and 2 hours after infection, and increased in amount exponentially for the following 3 hours. The released virus, as measured in the supernatant fluid, increased at the same rate but exceeded it in amount by a factor of about 20 at all times during the exponential rise period. More than 100 particles were spontaneously released by each cell by the end of this period, yet the maximum number of particles detectable within the cells at any instant by sonically vibrating them was not more than about 10 particles. Calculations revealed that on the average, a virus particle is released from the cell within 1 minute after it gains the property of infectiousness.