Epstein–Barr virus

Epstein–Barr virus
Liza Gross · CC BY 2.5 · source
Name	Epstein–Barr virus
Caption	Transmission electron micrograph of two virions
Taxon	Human gammaherpesvirus 4
Synonyms	Human herpesvirus 4 (HHV-4)

Epstein–Barr virus is a ubiquitous human pathogen belonging to the Herpesviridae family and the Gammaherpesvirinae subfamily. It is one of the most common viruses in humans, with over 90% of the global adult population exhibiting serological evidence of past infection. Primary infection often occurs in childhood and is typically asymptomatic, but when contracted during adolescence or adulthood, it can cause infectious mononucleosis. The virus establishes lifelong latency in B lymphocytes and is associated with several malignancies and autoimmune conditions.

Virology

The viral particle consists of a double-stranded DNA genome enclosed within an icosahedral capsid, surrounded by a tegument and a lipid envelope derived from the host cell membrane. The genome encodes approximately 85 proteins, including latent proteins like Epstein–Barr nuclear antigens and Latent membrane proteins that are crucial for immortalizing B cells. The virus primarily infects epithelial cells of the oropharynx and B cells via interaction with the cellular receptor CD21, also known as complement receptor 2. Research into its replication cycle has been advanced by studies at institutions like the University of Pennsylvania and the German Cancer Research Center.

Epidemiology

Infection is widespread across all human populations, with seroprevalence approaching 95% in adults worldwide. In developing regions and lower socioeconomic settings, primary infection usually occurs in early childhood. In developed countries such as the United States and United Kingdom, a significant proportion of individuals experience primary infection during adolescence, often presenting as infectious mononucleosis. The virus is transmitted primarily through saliva, earning it the nickname "the kissing disease," but can also spread via blood transfusion and organ transplantation. Notable epidemiological studies have been conducted by organizations like the World Health Organization and the Centers for Disease Control and Prevention.

Clinical manifestations

Primary infection in children is often asymptomatic, while in adolescents and adults it frequently causes infectious mononucleosis, characterized by fever, pharyngitis, lymphadenopathy, and fatigue. The virus is etiologically linked to several malignancies, including Hodgkin lymphoma, Burkitt lymphoma, nasopharyngeal carcinoma, and post-transplant lymphoproliferative disorder. It is also associated with conditions like multiple sclerosis, as supported by large-scale studies from Harvard University. Furthermore, it can cause oral hairy leukoplakia, particularly in immunocompromised individuals such as those with HIV/AIDS.

Diagnosis and treatment

Diagnosis of acute infection typically involves serological tests detecting heterophile antibodies, such as the Monospot test, or specific antibodies to viral capsid antigen and Epstein–Barr nuclear antigen. More precise methods include polymerase chain reaction assays to detect viral DNA in blood. There is no specific antiviral therapy licensed for routine infection; management of infectious mononucleosis is supportive, focusing on rest and symptom relief. In severe or immunocompromised cases, medications like acyclovir or valacyclovir may be used, though their efficacy is limited. Treatment for associated cancers follows standard oncological protocols, such as those used at the National Cancer Institute.

Research and vaccine development

Major research efforts focus on understanding the mechanisms of viral latency and oncogenesis, with significant contributions from scientists like Yvonne Barr and Michael Epstein. The association with multiple sclerosis has been a major area of investigation, highlighted by long-term studies from the United States Armed Forces. Developing a prophylactic vaccine remains a priority, with candidates targeting the viral glycoprotein gp350 having undergone clinical trials sponsored by the National Institute of Allergy and Infectious Diseases. Therapeutic vaccines and T cell therapies, such as those developed at the Fred Hutchinson Cancer Center, are also being explored for treating virus-associated cancers.

Category:Herpesviruses Category:Oncogenic viruses