Epstein-Barr virus (Salem Health: Cancer)
Related cancers: Burkitt lymphoma, a type of non-Hodgkin lymphoma (NHL), nasopharyngeal carcinoma
Definition: Epstein-Barr virus is one of the eight known types of human herpesviruses and is a member of the gamma subtype of this group. Like many herpesvirus species, Epstein-Barr virus appears to establish a lifelong presence in the human body, remaining quiescent for long periods of time and then inexplicably becoming active. Causally related to mononucleosis, it is also associated with a variety of human cancers, such as Burkitt lymphoma and nasopharyngeal carcinoma, and is therefore considered to be a carcinogenic virus.
Exposure routes: Humans are the only known reservoir of Epstein-Barr virus, which is present in oropharyngeal secretions and is most commonly transmitted through saliva; transmission of the virus requires intimate contact with the saliva (found in the mouth) of an infected person. Transmission through the air or blood does not usually occur. Epstein-Barr virus is causally related to infectious mononucleosis (IM), a disease characterized by the proliferation of single-nucleus white blood cells, resulting in fever, sore throat, and sometimes hepatitis. Infectious mononucleosis may be contagious for a period of weeks. However, isolation measures are not practical, since Epstein-Barr virus is frequently present in the saliva of healthy persons, who may carry and...
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For Further Information (Salem Health: Cancer)
Robertson, E. S. Epstein-Barr Virus. Portand, Oreg.: Caister Academic Press, 2005.
Tselis, A., and H. B. Jenson. Epstein-Barr Virus. New York: Taylor & Francis, 2006.
U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program. Eleventh Report on Carcinogens. Research Triangle Park, N.C.: Author, 2005.
Young, L. S., and A. B. Rickinson. “Epstein-Barr Virus: Forty Years On.” Nature Reviews: Cancer 4, no. 10 (2004): 757-768.
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Causes and Symptoms (Magill’s Medical Guide, Sixth Edition)
Present only in humans, Epstein-Barr virus was the first documented oncovirus. The virus, resembling other human herpesviruses, consists of sphere-shaped, barbed virions approximately 120 to 220 nanometers in diameter. Each Epstein-Barr virus genome contains two strands of deoxyribonucleic acid (DNA). A protein shell protects the genome, and an envelope surrounds the protein shell. Various Epstein-Barr virus strains have evolved that can infect an individual at the same time.
The Epstein-Barr virus typically infects salivary gland cells or B cells. Usually, Epstein-Barr viral infections are transmitted through saliva. Seeking host cells in order to replicate, the Epstein-Barr virus proliferates, creating approximately one hundred types of antigens, including nuclear antigen EBNA 1, which the Epstein-Barr virus uses to put its DNA into new cells created during cell division.
T cells fight Epstein-Barr virus antigens by destroying infected host cells. T cells and antibodies stay in the immune system to continue protecting against infection, regulating latency, and developing immunity. EBNA1 is necessary for the Epstein-Barr virus genomes to endure being latent. T cells cannot detect the antigen EBNA1 and attack those host cells, which results in the Epstein-Barr virus often being invisible to immune protection. Latent infections are not apparent, usually remaining passive, but they can become active, potentially...
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Treatment and Therapy (Magill’s Medical Guide, Sixth Edition)
Approximately 90 to 95 percent of humans globally at any time have been infected with Epstein-Barr virus, which remains latent and endures in their bodies until death. There is currently no way to eliminate the virus once infection has occurred. Treatment focuses instead on the diseases that Epstein-Barr virus causes.
Researchers have attempted to develop antiviral vaccines to stop the replication of Epstein-Barr virus. In the early twenty-first century, scientists at Queensland Institute of Medical Research developed a vaccine prototype to strengthen T cells combatting Epstein-Barr virus antigens.
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Perspective and Prospects (Magill’s Medical Guide, Sixth Edition)
The Epstein-Barr virus was located as a result of researchers seeking viruses possibly associated with cancer in humans, In 1961, London researcher M. Anthony Epstein attended a lecture at which Denis P. Burkitt discussed his work with tumors, later called Burkitt’s lymphoma, in African children’s facial bones. Epstein, experienced with investigating viruses causing animal tumors, wanted to examine Burkitt’s lymphoma tumor tissues to detect any viruses. The British Empire Cancer Campaign funded Epstein’s travel to Uganda to acquire a consistent supply of tumor samples for his Middlesex Hospital Medical School laboratory. Epstein tried unsuccessfully to locate a virus for a couple of years.
The U.S. National Cancer Institute presented Epstein $45,000 for his investigations, and he hired doctoral student Yvonne M. Barr and colleague Bert G. Achong to expand his laboratory work attempting to culture viruses. The trio successfully grew a Burkitt’s lymphoma cell line in culture. When cells from that sample were examined with an electron microscope, the London scientists saw viral particles with structural elements of herpesvirus. Scrutinizing the virions, the trio declared that they had isolated a previously unknown human herpesvirus. They published their results in a 1964 Lancet article. After Epstein-Barr virus was identified, additional investigators studied the virus to expand knowledge of its...
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For Further Information: (Magill’s Medical Guide, Sixth Edition)
Epstein, M. Anthony, and Bert G. Achong, eds. The Epstein-Barr Virus. New York: Springer, 1979.
Robertson, Erle S., ed. Epstein-Barr Virus. Wymondham, England: Caister Academic Press, 2005.
Tselis, Alex C., and Hal B. Jenson, eds. Epstein-Barr Virus. New York: Taylor & Francis, 2006.
Umar, Constantine S., ed. New Developments in Epstein-Barr Virus Research. New York: Nova Science, 2006.
Wilson, Joanna B., and Gerhard H. W. May, eds. Epstein-Barr Virus Protocols. Totowa, N.J.: Humana Press, 2001.
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Epstein-Barr Virus (Encyclopedia of Cancer)
Epstein-Barr Virus, or EBV, is the name given to a member of the herpesvirus family that is associated with a variety of illnessesrom infectious mononucleosis (IM), to nasal-pharyngeal cancer, and Burkitt's lymphoma.
Herpesviruses have long been known. The name actually comes from the Greek adjective herpestes, which means creeping. Many herpesvirus species appear to establish a life-long presence in the human body, remaining dormant for long periods and becoming active for some, often inexplicable, reason. EBV is only one of several members of the Herpesvirus family that have similar traits. Others include varicella zoster virushe cause of both chickenpox and shingles and the herpes simplex virus responsible for both cold sores and genital herpes. EBV is usually transmitted through saliva but not blood, and is not normally an airborne infection.EBV occurs in nearly all regions of the world, and is considered among the most common infectious viruses
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Epstein-Barr Virus (World of Microbiology and Immunology)
Epstein-Barr virus (EBV) is part of the family of human herpes viruses. Infectious mononucleosis (IM) is the most common disease manifestation of this virus, which once established in the host, can never be completely eradicated. Very little can be done to treat EBV; most methods can only alleviate resultant symptoms.
In addition to infectious mononucleosis, EBV has also been identified in association withlthough not necessarily believed to causes many as 50 different illnesses and diseases, including chronic fatigue syndrome, rheumatoid arthritis, arthralgia (joint pain without inflammation), and myalgia (muscle pain). While studying aplastic anemia (failure of bone marrow to produce sufficient red blood cells), researchers identified EBV in bone marrow cells of some patients, suggesting the virus may be one causative agent in the disease. Also, several types of cancer can be linked to presence of EBV, particularly in those with suppressed immune systems, for example, suffering from AIDS or having recently undergone kidney or liver transplantation. The diseases include hairy cell leukemia, Hodgkin's and non-Hodgkin lymphoma, Burkitt's lymphoma (cancer of the lymphatic system endemic to populations in Africa), and nasopharyngeal carcinoma (cancers of the nose, throat, and thymus gland, particularly prevalent in East Asia). Recently, EBV has been associated with malignant smooth-muscle tissue tumors in immunocompromised children. Such tumors were found in several children with AIDS and some who had received liver transplants. Conversely, it appears that immunosuppressed adults show no elevated rates of these tumors.
Epstein-Barr virus was first discovered in 1964 by three researcherspstein, Achong, and Barrhile studying a form of cancer prevalent in Africa called Burkitt's lymphoma. Later, its role in IM was identified. A surge of interest in the virus has now determined that up to 95% of all adults have been infected with EBV at some stage of their lives. In seriously immunocompromised individuals and those with inherited immune system deficiencies, the virus can become chronic, resulting in "chronic Epstein-Barr virus" which can be fatal.
EBV is restricted to a very few cells in the host. Initially, the infection begins with its occupation and replication in the thin layer of tissue lining the mouth, throat, and cervix, which allow viral replication. The virus then invades the B cells, which do not facilitate the virus's replication but do permit its occupation. Infected B cells may lie dormant for long periods or start rapidly producing new cells. Once activated in this way, the B cells often produce antibodies against the virus residing in them. EBV is controlled and contained by killer cells and suppressor cells known as CD4 T lymphocytes in the immune system. Later, certain cytotoxic (destructive) CD8 T lymphocytes with specific action against EBV also come into play. These cells normally defend the host against the spread of EBV for the life of the host.
A healthy body usually provides effective immunity to EBV in the form of several different antibodies, but when this natural defense mechanism is weakened by factors that suppress its normal functioningactors such as AIDS, organ transplantation, bone marrow failure, chemotherapy and other drugs used to treat malignancies, or even extended periods of lack of sleep and overexertionBV escape from their homes in the B cells, disseminate to other bodily tissue, and manifest in disease.
Infection is determined by testing for the antibodies produced by the immune system to fight the virus. The level of a particular antibodyhe heterophile antibodyn the blood stream is a good indicator of the intensity and stage of EBV infection. Even though EBV proliferates in the mouth and throat, cultures taken from that area to determine infection are time-consuming, cumbersome, and usually not accurate.
Spread of the virus from one person to another requires close contact. Because of viral proliferation and replication in the lining of the mouth, infectious mononucleosis is often dubbed "the kissing disease." Also, because it inhabits cervical cells, researchers now suspect EBV may be sexually transmitted. Rarely is EBV transmitted via blood transfusion.
EBV is one of the latent viruses, which means it may be present in the body, lying dormant often for many years and manifesting no symptoms of disease. The percentage of shedding (transmission) of the virus from the mouth is highest in people with active IM or who have become immunocompromised for other reasons. A person with active IM can prevent transmission of the disease by avoiding direct contactuch as kissingith uninfected people. However, shedding has been found to occur in 15% of adults who test positive for antibodies but who show no other signs of infection, thus allowing the virus to be transmitted. Research efforts are directed at finding a suitable vaccine.
The prevalence of antibodies against EBV in the general population is high in developing countries and lower socioeconomic groups where individuals become exposed to the virus at a very young age. In developed countries, such as the United States, only 50% of the population shows traces of antibody by the age of five years, with an additional 12% in college-aged adolescents, half of whom will actually develop IM. This situation indicates that children and young persons between the ages of 10 and 21 years are highly susceptible to IM in developed countries, making it a significant health problem among students.
See also Latent viruses and diseases; Mononucleosis, infectious; Viruses and responses to viral infection