Varicella zoster virus: out of Africa and into the research laboratory.

Abstract

This review updates on numerous topics relating to the evolutionary origins of varicella zoster virus (VZV), the replication cycle, virion assembly and the recent genomic analyses. VZV is one of eight human herpesviruses that have existed for at least 400 million years. It has co-evolved with humankind and is present in all nationalities globally. The pathogenesis of varicella (chickenpox) is dependent on viral replication and dispersion through the body in T-lymphocytes. VZV replication is similar to that of herpes simplex virus. A complete analysis of VZV transcripts has identified their relative abundance, with transcripts for the regulatory proteins (open reading frame) ORF62 and ORF63 among the greatest. Studies of virion assembly have shown that endocytosis pathways are involved in the envelopment process by the viral glycoproteins. The complete sequencing of five VZV strains has identified numerous single nucleotide polymorphisms, and in turn, VZV strains have been segregated into European/North American and Asian clades. Furthermore, a small number of mutant VZV strains have been identified. These results suggest more diversity between VZV strains than previously recognized.