Epstein – Barr Virus

The Epstein–Barr virus (EBV), also called human herpesvirus 4 (HHV-4), is a virus of the herpes family, and is one of the most common viruses in humans.

Structure and genome

The virus is approximately 122 nm to 180 nm in diameter and is composed of a double helix of DNA wrapped in a protein capsid. The capsid is surrounded by a tegument made of protein, which in turn is surrounded by a envelope made from lipids.The EBV DNA is about 192,000 base pairs long and contains about 85 genes.The viral envelope contains glycoproteins, which are essential to infection of the host cell.

 

Replication

It infects primarily lymphocytes and epithelial cells. In lymphocytes, the infection is usually non-productive, while virus is shed (produce infection) from infected epithelial cells.

EBV is casually associated with:

  • Burkitt’s Lymphoma in the tropics.
  • Nasopharyngeal cancer, particularly in china and south Asia, where certain diets acts as co-carcinogens.
  • B cell lymphomas in Immune suppressed individuals (as in organ transplantation or HIV).
  • Hodgkin’s lymphoma (in 40% of affected patients).
  • X-linked lymphoproliferative Disease (Duncan’s syndrome).
  • Non-Hodgkin’s lymphoma in AIDS.

Burkitt’s lymphoma is a B cell tumor that occurs with a high frequency in children in central Africa. The Epstein–Barr virus is named after Michael Anthony Epstein, a professor emeritus at the University of Bristol, and Yvonne Barr (born 1932 in London), a 1966 Ph.D graduate from theUniversity of London, who together discovered and documented the virus, So was named Esptein – Barr Virus.

A constant abnormality in BL tumor cells is a chromosomal rearrangement that results in the c-myc gene being placed next to an enhancer of an immunoglobulin gene. This results in the expression of c-myc at abnormally high levels. 

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