THE ABUNDANCE OF THE HERPES-SIMPLEX VIRUS TYPE-1 UL37 TEGUMENT PROTEIN IN VIRUS-PARTICLES IS CLOSELY CONTROLLED

The tegument region of herpes simplex virus type 1 virus particles con tains approximately 15 virus-encoded polypeptide species. One of the l ess abundant species is a 120 kDa protein specified by gene UL37. The abundance of the UL37 protein in infected cells was increased about 20 -fold by replacing the native promoter for gene UL37 with the strong i mmediate early promoter of human cytomegalovirus. This rise in abundan ce did not induce any detectable increase in the amount of UL37 protei n incorporated into virus particles. These data contrast with those pr eviously obtained for a second tegument protein VP22 whose level of in corporation was elevated by increasing its abundance in infected cells . Thus, for the UL37 protein, a mechanism exists to control its abunda nce in the tegument. Moreover, data obtained with light particles whic h lack the viral capsid suggest that this controlled incorporation is not directed by interaction with the capsid structure.