BK Virus, Molecular Detection, Quantitative, PCR, Urine
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Polyomaviruses are small (45 nm, approximately 5,000 bp), 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 5 years of age 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) post-transplantation.(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.
A prospective and diagnostic marker for the development of BK virus nephropathy in renal transplant recipients
Increasing copy levels of BK virus (BKV) DNA in serial specimens may indicate possible BKV-associated nephropathy (BKVAN) in kidney transplant patients.
Viral loads of >100,000 copies/mL in urine may also indicate a risk for BKVAN.
This assay does not cross react with other polyomaviruses, including JC virus and SV-40.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Serial monitoring of viral loads may be indicated to assess changing levels of BK virus (BKV) DNA.
This test is not to be used to screen healthy patients. It is to be used for patients with a clinical history or risk factors for BKV disease. Depending on the population, varying percentages of patients may be found to be positive.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Clinical References Provides recommendations for further in-depth reading of a clinical nature
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 Transplantation 2002;2(5):481
3. Hirsch HH: Polyomavirus BK Nephropathy: A (Re-)emerging complication in renal transplantation. Am J Transplantation 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