| Popis: |
All herpesviruses contain linear, double-stranded DNA genome surrounded by a 100-nm diameter icosahedral protein capsid core consisting of 162 capsomers. In thin-section electron micrographs, an electron transparent region, termed the tegument, surrounds the capsid, which in turn is surrounded by a lipid-containing envelope. Variations in tegument thickness and the state of the envelope result in reports of enveloped herpesviruses varying from l20nm to over 300nm in diameter (Roizman 1996). The herpesviruses were originally classified into families or subtypes (alpha-, beta- and gamma-herpesviruses) based upon their biological characteristics. This delineation was simple and required a few easily measured assays. Eventually, this delineation was too simple and inadequate. Herpesvirus classification now involves not only biological characterization, but tissue tropism, genomic organization, and protein comparisons. |
