Human Herpesvirus 6
The family Herpesviridae is comprised of viruses characterized by a distinct morphology. Virion particles are enveloped and have a diameter of ~200 nm. The icosahedral capsid contains a double-stranded linear DNA molecule with a molecular weight of 80–150 million daltons.
According to their biologic and molecular properties, herpesviruses are classified in three subfamilies (Alphaherpesvirinae, Betaherpesvirinae, Gammaherpesvirinae). Humans are the natural host for eight herpesviruses: herpes simplex 1 (HSV-1), herpes simplex 2 (HSV-2), varicella zoster virus (VZV), human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), human herpesvirus 7 (HHV-7), and human herpesvirus 8 (HHV-8), also known as Kaposi sarcoma-associated herpesvirus.
All herpesviruses have the important biologic characteristic of establishing lifelong latent infections within specific cells of the host after primary infection. Latent virus may occasionally...