The JC virus (JCV) is a type of human polyomavirus (formerly known as papovavirus) and is genetically similar to BK virus and SV40. It was discovered in 1971 and named after the two initials of the patient with progressive multifocal leukoencephalopathy (PML). The virus causes PML and other diseases only in cases of immunodeficiency, as in AIDS, or immunosuppression, as in organ transplant patients. Virus classification involves naming and placing viruses into a taxonomic system. ... A DNA virus is a virus that has DNA as its genetic material and does not use an RNA intermediate during replication. ... Species See text Polyomavirus is the sole genus of viruses within the family Polyomaviridae. ... Species See text Polyomavirus is the sole genus of viruses within the family Polyomaviridae. ... Species See text Polyomavirus is the sole genus of viruses within the family Polyomaviridae. ... BK virus is a member of the polyomavirus family. ... SV40 is an abbreviation for Simian vacuolating virus 40 or Simian virus 40, a polyomavirus that is found in both monkeys and humans. ... 1971 (MCMLXXI) was a common year starting on Friday (the link is to a full 1971 calendar). ... Progressive multifocal leukoencephalopathy (PML), also known as progressive multifocal leukoencephalitis, is a rare and usually fatal viral disease that is characterized by progressive damage (-pathy) or inflammation (-itis) of the white matter (leuko-) of the brain (-encephalo-) at multiple locations (multifocal). ... In medicine, immune deficiency (or immunodeficiency) is a state where the immune system is incapable of defending the organism from infectious disease. ... Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS or Aids) is a collection of symptoms and infections resulting from the specific damage to the immune system caused by the human immunodeficiency virus (HIV). ... Immunosuppression is the medical suppression of the immune system. ... Transplant redirects here. ...

Epidemiology

The virus is very common in the general population, infecting 70 to 90 percent of humans; most people acquire JCV in childhood or adolescence ^[1]. It is found in high concentrations in urban sewage worldwide, leading some researchers to suspect contaminated water as a typical route of infection ^[2].

Minor genetic variations are found consistently in different geographic areas; thus, genetic analysis of JC virus samples has been useful in tracing the history of human migration ^[3].

Infection and pathogenesis

The initial site of infection may be the tonsils ^[4], or possibly the gastrointestinal tract ^[2]. The virus then remains latent in the gastrointestinal tract ^[5] and can also infect epithelial cells in the kidneys, where it continues to reproduce, shedding virus particles in the urine. The Palatine tonsils with the soft palate, uvula, and tongue visible. ... The gastrointestinal tract or digestive tract, also referred to as the GI tract or the alimentary canal, (nourishment canal) or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and expels the remaining waste. ... Types of epithelium This article discusses the epithelium, an animal anatomical structure. ... The kidneys are bean-shaped excretory organs in vertebrates. ...

JCV can cross the blood-brain barrier into the central nervous system, where it infects oligodendrocytes and astrocytes, possibly through the 5-HT_2A serotonin receptor ^[6]. It is found within the brain even in people with no symptoms ^[7]. Freeze-fracture morphology of the blood-brain barrier of a rat The blood-brain barrier (abbreviated BBB, not to be confused with the blood-cerebrospinal fluid barrier, a function of the choroid plexus) is a membrane that controls the passage of substances from the blood into the central nervous system. ... A diagram showing the CNS: 1. ... Oligodendrocytes (from Greek literally meaning few tree cells), or oligodendroglia (Greek, few tree glue)[1], are a variety of neuroglia. ... Astrocytes, also known as astroglia, are characteristic star-shaped glial cells in the brain. ... In the field of neurochemistry, 5-HT receptors are receptors for the neurotransmitter and peripheral signal mediator serotonin, also known as 5-hydroxytryptamine or 5-HT. 5-HT receptors are located on the cell membrane of nerve cells and other cell types in animals and mediate the effects of serotonin... Serotonin (5-hydroxytryptamine, or 5-HT) is a monoamine neurotransmitter synthesized in serotonergic neurons in the central nervous system (CNS) and enterochromaffin cells in the gastrointestinal tract. ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ...

When immunodeficiency or immunosuppression allows JCV to reactivate, it attacks the previously infected tissues. In the kidneys, this results in hemorrhagic cystitis and ureteral stenosis; in the brain, it causes the usually fatal progressive multifocal leukoencephalopathy or PML by destroying oligodendrocytes. Several studies since 2000 have suggested that the virus is also linked to colorectal cancer, as JCV has been found in malignant colon tumors, but these findings are still controversial ^[8]. Transverse section of ureter. ... A stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure. ... In animals, the brain, or encephalon (Greek for in the head), is the control center of the central nervous system. ... Progressive multifocal leukoencephalopathy (PML), also known as progressive multifocal leukoencephalitis, is a rare and usually fatal viral disease that is characterized by progressive damage (-pathy) or inflammation (-itis) of the white matter (leuko-) of the brain (-encephalo-) at multiple locations (multifocal). ... Colorectal cancer, also called colon cancer or bowel cancer, includes cancerous growths in the colon, rectum and appendix. ... In the anatomy of the digestive system, the colon (> Greek ) is the part of the intestine from the caecum to the rectum. ...

References

1. ^ Padgett, B.L. and Walker, D.L. (1973). "Prevalence of antibodies in human sera against JC virus, an isolate from a case of progressive multifocal leukoencephalopathy". J. Infect. Dis. 127 (4): 467-470. PubMed.
2. ^ ^{a b} Bofill-Mas, S., Formiga-Cruz, M., Clemente-Casares, P., Calafell, F. and Girones, R. (2001). "Potential transmission of human polyomaviruses through the gastrointestinal tract after exposure to virions or viral DNA". J. Virol. 75 (21): 10290-10299. PubMed.
3. ^ Pavesi, A. (2005). "Utility of JC polyomavirus in tracing the pattern of human migrations dating to prehistoric times.". J. Gen. Virol. 86 (Pt 5): 1315-1326. PubMed.
4. ^ Monaco, M.C., Jensen, P.N., Hou, J., Durham, L.C. and Major, E.O. (1998). "Detection of JC virus DNA in human tonsil tissue: evidence for site of initial viral infection". J. Virol. 72 (12): 9918-9923. PubMed.
5. ^ Ricciardiello, L., Laghi, L., Ramamirtham, P., Chang, C.L., Chang, D.K., Randolph, A.E. and Boland, C.R. (2000). "JC virus DNA sequences are frequently present in the human upper and lower gastrointestinal tract". Gastroenterology 119 (5): 1228-1235. PubMed.
6. ^ Elphick, G.F., Querbes, W., Jordan, J.A., Gee, G.V., Eash, S., Manley, K., Dugan, A., Stanifer, M., Bhatnagar, A., Kroeze, W.K., Roth, B.L. and Atwood, W.J. (2004). "The human polyomavirus, JCV, uses serotonin receptors to infect cells". Science 306 (5700): 1380-1383. PubMed.
7. ^ White, F.A., 3rd., Ishaq, M., Stoner, G.L. and Frisque, R.J. (1992). "JC virus DNA is present in many human brain samples from patients without progressive multifocal leukoencephalopathy". J. Virol. 66 (10): 5726-5734. PubMed.
8. ^ Theodoropoulos, G., Panoussopoulos, D., Papaconstantinou, I., Gazouli, M., Perdiki, M., Bramis, J. and Lazaris, ACh. (2005). "Assessment of JC polyoma virus in colon neoplasms". Dis. Colon. Rectum. 48 (1): 86-91. PubMed.

External links

• MS drug Tysabri link to JC virus and progressive multifocal leukoencephalopathy, or PML.