Epstein-Barr Virus Definition

A member of the herpesvirus family best known for causing the illness infectious mononucleosis. Infection with the epstein-barr virus, also called human herpesvirus-4 (HHV-4), causes other disease as well and was the first virus researchers linked with cancer (notably Burkitt’s lymphoma).

Epstein-Barr virus is ubiquitous; it infects more than 90 percent of Americans by age 25.

Causes of Epstein-Barr virus

As is characteristic of herpesvirus infections, Epstein-Barr virus causes first an acute illness (infectious mononucleosis), then retreats into a state of dormancy and remains in the body as a latent infection that does not cause illness or symptoms.

B-cell lymphocytes, white blood cells key to antibody-mediated immunity, harbor the latent Epstein-Barr virus. Though the virus does not change the ability of its host B-cell lymphocytes to function within the immune response, it does alter their DNA such that they become immortalized-they lose their genetic encoding for apoptosis, the natural process for cell death.

Only a small percentage of B-cell lymphocytes contain the virus, so for the most part immune function continues as normal. A healthy immune system maintains a balance between B-cell lymphocytes and T-cell lymphocytes (white blood cells key to cell-mediated immunity) that prevents B-cell lymphocytes containing the latent Epstein-Barr virus from endlessly proliferating. As a result of this balance, in most people the virus never regains enough presence to again cause illness.

Circumstances that challenge the immune system allow the Epstein-Barr virus to reactivate. The most notable of these circumstances are hiv/aids and immunosuppressive therapy after organ transplantation.

The reactivated Epstein-Barr virus may cause symptoms similar to infectious mononucleosis (chronic infectious mononucleosis) during which the person may spread the virus to others. It may also cause lymphoproliferative disorders: abnormal growth (tumors) of lymphatic structures such as lymph nodes and mucosa-associated lymphoid tissue (MALT).

Though research is under way to develop a vaccine to prevent infection with Epstein-Barr virus, at present there are no effective measures to prevent infection with the virus and no treatments to eradicate the virus once it establishes infection.

Diseaseas Associated With Epstein-Barr Virus

DISEASES ASSOCIATED WITH EPSTEIN-BARR VIRUS
acute infectiousaids-associated lymphoma
mononucleosisBurkitt’s lymphoma
chronic infectious mononucleosisgeneralized lymphoproliferative disease
nasopharyngeal carcinomapost-transplant lymphoproliferative disorder (PTLD)

See also B-CELL LYMPHOCYTECELL STRUCTURE AND FUNCTIONHERPES SIMPLEXHERPES ZOSTER; KAPOSI’S SARCOMALYMPH NODE; LYMPHOCYTEMONONUCLEOSIS, INFECTIOUSOPPORTUNISTIC INFECTIONT-CELL LYMPHOCYTE.

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