Structural model of a herpesvirus particle. The herpesvirus group of DNAcontaining viruses cause infections in man & animals. Genital herpes & chickenpox are examples of human diseases caused by types of herpesviruses. The group also includes the cytomegalovirus and EpsteinBarr virus. The virus is spherical, with an outer lipoprotein envelope of 150200 nanonmetres in diameter. Beneath the envelope is the icosahedral nucleocapsid, which encloses the DNA, the genetic information for encoding about 60 distinct proteins.