The Epstein-Barr virus (EBV) is one of the most common viruses in humans and is most commonly associated with infectious mononucleosis or glandular fever. It has also been linked to the development of several cancers including Hodgkin's lymphoma, nasopharyngeal carcinoma and Burkitt's lymphoma.

Virus class and taxonomy

EBV is a virus of the herpes family and, specifically, the genus lymphocryptovirus. EBV is otherwise known of as human herpesvirus 4 (HHV-4).

Structure

EBV is composed of double-stranded DNA of about 172 kilobase pairs in length and containing around 85 genes. This is surrounded by a nucleocapsid made up of 162 capsomeres. The nucleocapsid is contained in an outer protein covering that is surrounded by the viral envelope. The viral envelope is covered in glycoproteins that are essential in enabling the virus to infect host cells.

Transmission

The EBV virus is caught by people who are not immune to the virus when they come into contact with EBV- infected saliva. The virus can therefore be transmitted through close contact with infected individuals while kissing or even through sharing drinks or toothbrushes, for example. EBV then infects the pharyngeal cells lining the surfaces of the throat, mouth and nose.

The infection is usually picked up during childhood but may not be caught until adolescence, in which case it usually causes glandular fever.

The virus's main target is the B lymphocyte and it spreads throughout the lymphatic system causing swelling of the lymph nodes and lymph glands. The virus may reach the spleen, which may become inflamed and swollen. This happens in about half of glandular fever cases.

People who have suppressed immunity, for example those with HIV infection or those taking steroids or chemotherapeutic agents are at increased risk of infection with EBV.