[Structure and classification of alpha-herpesvirus]

Virion of herpesviruses (100 to 200 nm in diameter) consists of a core containing a linear double-stranded DNA, an icosahedral capsid, an amorphous layer designated as the tegument which surrounds the capsid, and a protein-containing lipid membrane designated as the envelope. Terminal and internal reiterated sequences are present on herpesvirus genomes, giving a diverse range of DNA structures. The family Herpesviridae is divided into three subfamily of Alpah-, Beta- and Gammaherpesvirinae. Herpesviruses seem to have diversified from a common ancestor, in a manner mediating co-speciation of herpesviruses with host species through species-specific latent infection.