Cytomegalovirus Primary Envelopment at Large Nuclear Membrane Infoldings: What's New?

Cytomegalovirus morphogenesis has been the object of ultrastructural studies by electron microscopy (EM) since the 1960s, and the nuclear egress of nucleocapsids has been accurately documented by several studies which, despite the use of the “oldest” fixation methods, observed and described the infoldings at the inner nuclear membrane and hypothesized their active role in the primary envelopment and the early step of the maturation of virions (2-7).