Epstein-Barr Virus (EBV) or Human Herpesvirus 4- An Overview


Epstein-Barr virus (EBV) is a member of the herpesvirus family and one of the most common human viruses. It causes infectious mononucleosis and is associated with various cancers and autoimmune diseases.

Structure of EBV

The structure of EBV is similar to other herpesviruses. It consists of a double-stranded DNA genome surrounded by an icosahedral protein capsid containing 162 capsomers. A protein tegument is present between the capsid and the envelope embedded with glycoproteins that play a part in cell tropism, host range, and cell recognition. The mature virions are approximately 120 to 180 nm in diameter.

The following diagram shows a simplified structure of EBV:

Subtypes of EBV

There are currently two recognized subtypes of EBV; Type 1 and Type 2, also referred to as Type A and Type B, respectively. These subtypes differ from one another at the EBV nuclear antigen loci (EBNA). EBNA are proteins expressed by the virus during latency that help the virus evade the immune system and maintain its episomal state in the infected cells.

Type 1 EBV is more prevalent and more efficient in transforming B cells than Type 2 EBV. Type 2 EBV is more common in Africa and is associated with Burkitt`s lymphoma, a type of cancer that affects B cells.

The following table summarizes some of the differences between Type 1 and Type 2 EBV:

Type 1 P-thr-leu-pro-gly repeat RGGG repeat RGGG repeat RGGG repeat RGGG repeat RGGG repeat
Type 2 M-thr-leu-pro-gly repeat RGGG repeat RGGG repeat RGGG repeat RGGG repeat RGGG repeat