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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 infectious||AIDS-associated lymphoma|
|chronic infectious mononucleosis||generalized lymphoproliferative disease|
|nasopharyngeal CARCINOMA||post-transplant lymphoproliferative disorder (PTLD)|
See also B-CELL LYMPHOCYTE; CELL STRUCTURE AND FUNCTION; HERPES SIMPLEX; HERPES ZOSTER; KAPOSI’S SARCOMA; LYMPH NODE; LYMPHOCYTE; MONONUCLEOSIS, INFECTIOUS; OPPORTUNISTIC INFECTION; T-CELL LYMPHOCYTE.