The structural proteins and glycoproteins of herpesviruses: a review

The virions of different herpesviruses are similar with respect to the number and kinds of constituent polypeptides, in spite of variability in the structures of individual polypeptides. The total number of virion polypeptides and glycopeptides ranges from 20 to 30 for different viruses and, in general, no more than one-quarter of these polypeptides is detectable in naked nucleocapsids, implying that most of the virion polypeptides are acquired during the process of envelopment. Although the functions of most individual structural proteins have not been identified, one can predict that the nucleocapsid proteins serve primarily structural roles or may mediate packaging of the viral genome, that the non-glycosylated envelope proteins play essential roles in the process of envelopment and that the glycoproteins, which are probably all exposed to the virion surface, mediate adsorption to and penetration of the host cell. Two of the herpes simplex virus glycoproteins have been identified as targets of neutralizing antibodies and one of these proteins has been shown to mediate viral penetration, probably by promoting fusion between the virion envelope and cell surface membrane.