Proteins in mouse embryonic cell (MEC) culture fluids following interferon induction.

A study was made on the proteins and interferon activity in supernatant culture fluids from mouse fibroblast cultures induced with Newcastle disease virus, and in controls. The studied materials showed low protein content, the concentration of proteins depending on the length of time from induction to their collection. Proteins from induced and control cultures were separated on CM-Sephadex C-50 and by electrophoresis in polyacrylamide gel. No difference was found in the character of proteins from control materials and from materials induced 24 hours after infection; the elution profile was the same, and the distribution of electrophoretic fractions was similar. Interferon activity was not accompanied by the appearance of a new protein fraction. However, 5--10 hours after induction differences were noted in electrophoretic mobility and a marked reduction in the number of protein fractions occurred in control and stimulated culture fluids.