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Polyomaviruses are small (45 nm, approximately 5,000 base pairs), DNA-containing viruses and include 3 closely related viruses of clinical significance; SV-40, JC virus (JCV), and BK virus (BKV). SV-40 naturally infects rhesus monkeys but can infect humans, while BKV and JCV cause productive infection only in humans.(1,2) Acquisition of BKV begins in infancy. Serological evidence of infection by BKV is present in 37% of individuals by age 5 and over 80% of adolescents.
BKV is an important cause of interstitial nephritis and associated nephropathy (BKVAN) in recipients of kidney transplants. Up to 5% of renal allograft recipients can be affected about 40 weeks (range 6-150) posttransplantation.(3) PCR analysis of BKV DNA in the plasma is the most widely used blood test for the laboratory diagnosis of BKV-associated nephropathy. Importantly, the presence of BKV DNA in blood reflects the dynamics of the disease: the conversion of plasma from negative to positive for BKV DNA after transplantation, the presence of DNA in plasma in conjunction with the persistence of nephropathy, and its disappearance from plasma after the reduction of immunosuppressive therapy.(4-8) However, BKV DNA is typically detectable in urine prior to plasma and may serve as an indication of impending BKVAN. Viral loads of >100,000 copies/mL in urine may also indicate a risk for BKVAN (see QBKU / BK Virus, Molecular Detection, Quantitative, PCR, Urine).
Rapid detection of BK virus DNA
Results of urine tests are reported in terms of the presence or absence of BK virus (BKV).
Detection of BKV DNA in clinical specimens may support the clinical diagnosis of renal or urologic disease due to BKV. Correlation of qualitative results with clinical presentation and BK-viral load in urine and/or plasma is recommended.
A negative result does not rule-out the possibility of BK virus (BKV) infection.
This assay is only to be used in patients with appropriate risk factors for BK-associated disease and is not indicated for screening of asymptomatic patients.
1. Kazory A, Ducloux D: Renal transplantation and polyomavirus infection: recent clinical facts and controversies. Transplant Infect Dis 2003;5(2):65
2. Vilchez RA, Arrington AS, Butel JS: Polyomaviruses in kidney transplant recipients. Am J Transplant 2002;2(5):481
3. Hirsch HH: Polyomavirus BK Nephropathy: A (Re-)emerging complication in renal transplantation. Am J Transplant 2002;2(1):25-30
4. Randhawa PS, Demetris AJ: Nephropathy due to polyomavirus type BK. N Engl J Med 2000;342:1361-1363
5. Volker NT, Klimkait IF, Binet P, et al: Testing for polyomavirus type BK DNA in plasma to identify renal-allograft recipients with viral nephropathy. N Engl J Med 2000;342:1309-1315
6. Hariharan S: BK virus nephritis after renal transplantation. Kidney Int 2006;69:655-662
7. Blanckaert K, De Vriese AS: Current recommendations for diagnosis and management of polyoma BK virus nephropathy in renal transplant recipients. Nephrol Dial Transplant 2006;21(12):3364-3367
8. Viscount HB, Eid AJ, Espy MJ, et al: Polyomavirus polymerase chain reaction as a surrogate marker of polyomavirus-associated nephropathy. Transplantation 2007;84(3):340-345