An additional role for the outer nuclear membrane in the morphogenesis of herpes simplex virus.

Ultrastructural study of MRC-5 cells infected by herpes simplex virus yielded several examples of physical continuity between the outer nuclear membrane and the envelope of viral particles in the perinuclear cisterna, suggesting a fusion between the two. Such virions would thus lose their envelope and enter the cytoplasm as naked capsids. Fusion first occurred at 6-8 h postinfection (p.i.), while naked cytoplasmic capsids appeared at 6 h p.i. Since nuclear membrane disruption was not observed until 24 h p.i., it is unlikely to account for the early appearance of these capsids. Thus, in addition to its other roles, the outer nuclear membrane may be involved in naked cytoplasmic capsid production via a fusion event.