Retinoic acid reduces the yield of herpes simplex virus in Vero cells and alters the N-glycosylation of viral envelope proteins

Treatment of Vero cells with all-trans-retinoic acid (RA) decreased the pro duction of infectious herpes simplex virus (HSV) by 1000-10 000-fold when c ompared with control cultures. Levels of total HSV envelope glycoproteins g B, gC and gB produced following RA treatment, were comparable with those fo und in control cultures. Following 24 h of RA treatment, lower molecular we ight variants of gB, gC and go were produced in addition to the typical mol ecular mass of each protein found in control samples. Between 24 and 48 h o f RA treatment, the proportion of the lower molecular mass variants increas ed. When control and RA treated samples were incubated with peptide N-glyco sidase F (PNGase F), which removes N-glycosylated sugars, the molecular wei ghts of the respective gB, gC and go proteins produced were comparable in b oth the groups, indicating that RA did not alter the primary sequence of vi ral proteins during protein synthesis or increase viral protein proteolysis . RA treatment increased [H-3]mannose incorporation into glycoproteins in H SV infected cells but did not change [H-3]glucosamine incorporation. We con clude that RA treatment does not reduce the synthesis of three major viral envelope glycoproteins but alters their N-glycosylation and postulate that the inhibitory effect of RA is related to its action on N-glycosylation. (C ) 2000 Elsevier Science B.V. All rights reserved.