Genomic variants among human cytomegalovirus (HCMV) clinical isolates: the glycoprotein n (gN) paradigm.

Human cytomegalovirus (HCMV) clinical isolates display genetic polymorphisms, which are supposed to be implicated in strain-specific tissue tropism and HCMV-induced immunopathogenesis. One highly variable gene is ORF UL73, encoding for the envelope glycoprotein gN, which displays both a structural and an immunologic role as a component of the high-molecular weight complex gC-II. UL73 showed clustered polymorphisms, which originate four distinct genomic variants, denoted gN-1, gN-2, gN-3, and gN-4. This review reports the main features of gN genotypes and their potential implications on HCMV biologic properties. The clinical impact of gN variants is also discussed. This overview on gN clustered polymorphisms should be useful as a prototype model for a better understanding of the biologic and clinical relevance of HCMV clinical isolates genetic variability.