Epidemiology of human cytomegalovirus strains through comparison of methodological approaches to explore gN variants

Genomic variation among human cytomegalovirus (HCMV) wild-type strains is a well-documented phenomenon probably implicated in HCMV-induced immunopathogenesis. Extensive genetic polymorphism has been detected for the envelope glycoprotein N (gN) and HCMV clinical isolates have been clustered into seven distinct gN variants (gN-1, gN-2, gN-3a, gN-3b, gN-4a, gN-4b, gN-4c). Several studies from different research groups worldwide have addressed this topic using different methodological approaches (PCR-RFLP, PCR-Cloning, PCR-Sequencing) and sometimes yielding apparently conflicting results. This paper analyses the epidemiology of HCMV strains through analysis of gN variants, criticizing the methodological approaches and study populations by comparison of published reports.