Effect of tunicamycin on herpes simplex virus glycoproteins and infectious virus production

Abstract

Tunicamycin, which blocks glycoprotein synthesis, inhibited the production of infectious herpes simplex virus. In the presence of this drug, [14C]glucosamine and [3H]mannose incorporation was reduced in infected cells [hamster kidney BHK]; total protein synthesis was not affected. Gel electrophoresis of [2-3H]mannose-labeled polypeptides failed to detect glycoprotein D or any of the other herpes simplex virus glycoproteins. Use of specific antisera demonstrated that in the presence of tunicamycin the normal precursors to viral glycoproteins failed to appear. Instead, lower-MW polypeptides were found which were antigenically and structurally related to the glycosylated proteins. Blocking the addition of carbohydrate to glycoprotein precursors with tunicamycin results in the disappearance of molecules, possibly due to degradation of the unglycosylated polypeptides. The added carbohydrate either stabilizes the envelope proteins or provides the proper structure for correct processing of the molecules needed for infectivity.