Ultrastructural Localization of the Herpes Simplex Virus Type 1 U L 31, U L 34, and U S 3 Proteins Suggests Specific Roles in Primary Envelopment and Egress of Nucleocapsids

Abstract

The wild-type U L 31, U L 34, and U S 3 proteins localized on nuclear membranes and perinuclear virions; the U S 3 protein was also on cytoplasmic membranes and extranuclear virions. The U L 31 and U L 34 proteins were not detected in extracellular virions. U S 3 deletion caused (i) virion accumulation in nuclear membrane invaginations, (ii) delayed virus production onset, and (iii) reduced peak virus titers. These data support the herpes simplex virus type 1 deenvelopment-reenvelopment model of virion egress and suggest that the U S 3 protein plays an important, but nonessential, role in the egress pathway.