Herpesviridae is the
name of a family of enveloped, double-stranded DNA viruses
with similar ultrastructural features.
Members of the Herpesviridae family of viruses are classified into the alpha, beta and gamma subfamilies.
Herpesviruses all have icosahedral symmetry and all are about the same size (approximately 200 nm across).
They are among the largest viruses.
They replicate in the cell nucleus, have an affinity for cells of ectodermal origin, produce vesicles or pocks, and produce latent infections.
Herpesviruses include eight human viruses (HHV) and numerous animal viruses. The human herpesviruses, are named from 1 to 8.
HHV-1 and HHV-2: Herpes simplex virus, types 1 and 2 ;
HHV-3: Varicella-zoster virus ;
HHV-4: Epstein-Barr virus (EBV) ;
HHV-6 (Roseolovirus) causes "sixth disease" (known as roseola infantum or exanthem subitum).
HHV-7 is closely related to HHV-6 and causes almost the same symptoms.
HHV-8 is a type of rhadinovirus. KSHV- Kaposi's arcoma associated herpes virus causes Kaposi's sarcoma , primary effusion lymphoma and some types of multicentric Castleman's disease.
Herpes Simplex Virus 1 and 2 cause "fever-blisters" and genital lesions, respectively.
Each of these viruses may disseminate and kill patients with defective or suppressed immunity.
A principal histologic feature is the formation of Cowdry type A intranuclear inclusions in epithelial and other cells of the host.
Those acidophilic (red with eosin) inclusions have a diameter that exceeds half the diameter of the nucleus and are surrounded by a clear zone ("halo") of vacant nucleoplasm.
Herpes virus infection also cause the formation of syncytial giant cells by aggression and fusion of infected epithelial cells.
These giant cells may also contain intranuclear inclusions.
The neurotropic herpes viruses, HSV-1, HSV-2 and VZV, colonize and establish latent infection in human peripheral sensory ganglia.
Although all three viruses belong to the same family and establish latent infection in the same tissue, the clinical pattern of their reactivation is quite different.
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