BK virus

Taxobox
virus_group = i
familia = "Polyomaviridae"
genus = "Polyomavirus"

The BK virus is a member of the polyomavirus family. Past infection with the BK virus is widespread, but significant consequences of infection are uncommon, with the exception of the immunocompromised and the immunosuppressed.

The BK virus was first isolated in 1971 in the urine of a renal transplant patient, initials B.K. [William E. Braun MD. "BK polyomavirus: A newly recognized threat to transplanted kidneys." Cleveland Clinic Journal of Medicine, Vol 70, Number 12, Dec 2003. [http://www.ccjm.org/pdffiles/Braun1203.PDF] ] This BK virus is similar to another virus called the JCV since their genome sequence share 75% homology. Both of these viruses can be identified and differentiated from each other by carrying out serological tests using specific antibodies.

The BK virus rarely causes disease since many people who are infected with this virus are asymptomatic. If symptoms do appear then many of them will be mild such as having a respiratory infection or a fever. These are known as the primary infections. Latent infections can occur in the kidneys and sometimes in the brain. A latent infection occurs when the virus becomes reactivated. However it is not known how this virus is transmitted. It is known however that the virus is spread from person to person and not from an animal source. It has been suggested that this virus may be transmitted through respiratory fluids.

In some renal transplant patients, the necessary use of immunosuppresant medications has the side-effect of allowing the virus to manifest itself and ultimately attack the kidney via BK nephropathy. [Fishman J. "BK Virus Nephropathy — Polyomavirus Adding Insult to Injury." New England Journal of Medicine 15 Aug, 2002] It is also associated with ureteral stenosis and interstitial nephritis. In bone marrow transplant recipients it is notable as a cause for hemorrhagic cystitis. In addition, the presence of BK polyoma in the bladder is statistically linked to the development of bladder carcinoma. [Weinreb DB, Desman GT, Amolat-Apiado MJ, Burstein DE, Godbold JH Jr, Johnson EM. "Polyoma virus infection is a prominent risk factor for bladder carcinoma in immunocompetent individuals." Diagn Cytopathol. 2006 Mar;34(3):201-3. PMID 16470860]

This virus can be diagnosed by BKV blood & urine testing, in addition to carrying out a biopsy in the kidneys. PCR techniques and LAMP (Loop mediated isothermal amplification) can also be carried out to identify the virus. [Bista BR, Ishwad C, Wadowsky RM, Manna P, Randhawa PS, Gupta G, Adhikari M, Tyagi R, Gasper G, Vats A. "Development of Loop Mediated Isothermal Amplification Assay for Rapid Detection of BK virus." Journal of Clinical Microbiology. 2007 May;45(5):1581-7. PMID 17314224] Renal transplant patients infected with this virus can be treated by using cidofovir which is an antiviral drug. Cidofovir is a nucleotide analogue that has the ability to interfere with the action of the BK virus. It is known to have treated individuals with a renal transplant that were infected with this virus. In addition, therapy with leflunomide, an anti-inflammatory drug approved for the treatment of rheumatoid arthritis, is now widely prescribed. The drug acts not only as an antiviral effective against BK but also as an immunosuppresant, particularly promising for renal transplant recipients. [Blanckaert K & De Vriese AS. "Current recommendations for diagnosis and management of polyoma BK virus nephropathy in renal transplant recipients." Nephrology Dialysis Transplantation 2006 21(12):3364-3367; doi:10.1093/ndt/gfl404]

References

* [http://www.viracor.com/diagnostic-virals-bk_overview.htm Overview of the BK virus]
* [http://www.microbiologybytes.com/virology/Polyomaviruses.html MicrobiologyBytes: Polyomaviruses]
* [http://www.journals.uchicago.edu/CID/journal/issues/v33n2/000985/000985.web.pdf?erFrom=4686272597938696814Guest Reploeg, MD., Storch, GA., Clifford, DB., BK virus: A clinical review]
* [http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1600-6135.2004.00730.x?cookieSet=1 Blackwell Munksgaard, 2004. BK virus. American Journal of Transplantation.]
* [http://ndt.oxfordjournals.org/cgi/content/full/21/12/3364 Katrien Blanckaert and An S. De Vriese, 2006. Nephrology Dialysis Transplantation, journal of the European Renal Association and the European Dialysis and Transplant Association]