The effect of cycloheximide on the accumulation and stability of functional alpha-mRNA in cells infected with herpes simplex virus.

Cells were infected with herpes simplex virus type 2, HSV-2(G), and incubated in the presence of cycloheximide (CX). When CX was removed and actinomycin D (Act D) added, alpha-polypeptides ICP 0 and ICP 4 were synthesized at low rates. If CX was removed without adding Act D, the rate of production of ICP 4 increased while that of ICP 0 remained constant. In cells treated with azetidine to enhance the production of ICP 4 and 0, accumulation of functional mRNA for ICP 4 (determined indirectly by translation in vivo) was reduced by concentrations of CX between 0.5 and 5.0 micrograms/ml, whereas mRNA for ICP 0 was unaffected by 50 micrograms/ml CX. CX apparently either inhibits the synthesis of ICP 4 mRNA or enhances its inactivation without affecting the production or degradation of ICP 0 mRNA. The accumulation of ICP 4 or ICP 0 mRNA of HSV-1(F) was unaffected by CX. The low levels of ICP 4 and ICP 0 mRNAs of HSV-2(G) that accumulated in the presence of CX disappeared rapidly after adding Act D, in contrast to those of HSV-1(F) which were stable. The ICP 4 mRNA of HSV-2(G) was stable, however, if made without CX or if in mixed infection with HSV-1(F) in the presence of CX. It is suggested that rapid inactivation may account for the low level of accumulation of functional ICP 4 and ICP 0 mRNAs of HSV-2(G) in the presence of CX, and that ICP 4 mRNA is protected by a protein made soon after normal infection. Such a protein may be carried in the virion of HSV-1(F).