Production of an Inhibitor Substance by DA Myxovirus. Auto-Inhibition of Plaque Formation.

Abstract

Auto-inhibition of DA virus plaque formation was observed in tissue cultures during serial passages of this virus. An inhibitor (interferon-like) substance was found in the virus-free culture fluids. The presence of such an inhibitor substance seemed to be the determining factor for the 2 unusual phenomena observed with the DA virus: 1) plaque formation under agar overlay without CPE in parallel fluid cultures, and 2) “prozone“ reaction in plaque formation.