Herpes Viruses

Introduction
All herpes viruses can develop a latent state within specific tissues, in which they rest until reactivation. Reactivation is triggered by menstruation, anxiety states, fever, sunlight exposure, or weakening of the immune system. Viruses cause cells to become multinucleated giant syncytial cells with intranuclear inclusion bodies, and cause local destruction when they migrate to the peripheral skin. Disease is resisted by cell-mediated immunity, but the virus remains latent in nerve cells throughout one's life.

Only alpha subfamily viruses (herpes simplex 1 and 2, and varicella zoster) cause cell damage to the skin.

Herpes simplex virus 1 & 2
Latent in nerve cell bodies. HSV-1 produces most cold sores and HSV-2 produces most genital herpes. Symptoms include watery blisters in the skin or mucous membranes of the mouth, lips or genitals. Herpes simplex can be spread through contact with saliva. HSV infection during pregnancy can result in transplacental viral transfer (by crossing the blood-placenta barrier).

Varicella zoster virus 
Latent in nerve cell bodies. Causes varicella (chickenpox) AND herpes zoster (shingles). A breakout of shingles causes painful skin rashes.

Cytomegalovirus
Latent in salivary glands, and dendritic and myeloid cells. CMV infects both epithelial cells and various cells of the immune system. Infection is typically unnoticed in healthy people, but can be life-threatening for the immunocompromised. CMV causes four infectious states: (1) Asymptomatic (2) Congenital disease in infants by transmission from mother, causing mental retardation (3) Mononucleosis syndrome in young adults (4) Reactivation, causing retinitis (blindness), pneumonia or disseminated infection.

Epstein-Barr virus
Latent as multiple copies of circular DNA. Causes mononucleosis by infecting B cells, and is involved in certain cancers. EBV causes cells to "transform" and act as cancer cells, passing on copies of EBV DNA to their progeny. However, malignant cells are cleared by the immune system, with the resolution of mononucleosis illness.