title: The human polyomavirus BK (BKPyV): virological background and clinical implications.
abstract: Polyomavirus BK (BKPyV) infects most people subclinically during childhood and establishes a lifelong infection in the renourinary tract. In most immunocompetent individuals, the infection is completely asymptomatic, despite frequent episodes of viral reactivation with shedding into the urine. In immunocompromised patients, reactivation followed by high-level viral replication can lead to severe disease: 1-10% of kidney transplant patients develop polyomavirus-associated nephropathy (PyVAN) and 5-15% of allogenic hematopoietic stem cell transplant patients develop polyomavirus-associated haemorrhagic cystitis (PyVHC). Other conditions such as ureteric stenosis, encephalitis, meningoencephalitis, pneumonia and vasculopathy have also been associated with BKPyV infection in immunocompromised individuals. Although BKPyV has been associated with cancer development, especially in the bladder, definitive evidence of a role in human malignancy is lacking. Diagnosis of PyVAN and PyVHC is mainly achieved by quantitative PCR of urine and plasma, but also by cytology, immunohistology and electron microscopy. Despite more than 40 years of research on BKPyV, there is still no effective antiviral therapy. The current treatment strategy for PyVAN is to allow reconstitution of immune function by reducing or changing the immunosuppressive medication. For PyVHC, treatment is purely supportive. Here, we present a summary of the accrued knowledge regarding BKPyV.
authors.affiliation: Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway. christine.rinaldo@unn.no
authors.forename: Christine Hanssen
authors.initials: CH
authors.lastname: Rinaldo
authors.forename: Garth D
authors.initials: GD
authors.lastname: Tylden
authors.forename: Biswa Nath
authors.initials: BN
authors.lastname: Sharma
mesh_terms: D001739:BK Virus / Q000145:classification / Q000302:isolation & purification / Q000472:pathogenicity* / Q000502:physiology; D020805:Central Nervous System Viral Diseases / Q000150:complications / Q000473:pathology; D003556:Cystitis / Q000150:complications / Q000473:pathology / Q000821:virology; D018380:Hematopoietic Stem Cell Transplantation; D006470:Hemorrhage / Q000150:complications / Q000473:pathology / Q000821:virology; D006801:Humans; D016867:Immunocompromised Host; D007674:Kidney Diseases / Q000150:complications / Q000473:pathology / Q000821:virology; D016030:Kidney Transplantation; D009369:Neoplasms / Q000150:complications / Q000473:pathology / Q000821:virology; D016133:Polymerase Chain Reaction; D027601:Polyomavirus Infections / Q000150:complications / Q000188:drug therapy / Q000473:pathology*; D001743:Urinary Bladder / Q000473:pathology / Q000821:virology; D014779:Virus Replication
keywords: Polyomavirus BK; hematopoietic stem cell transplantation; immunosuppression; kidney transplantation; polyomavirus-associated haemorrhagic cyctitis; polyomavirus-associated nephropathy