title: Optimal use of plasma and urine BK viral loads for screening and predicting BK nephropathy.
abstract: BK virus is a polyoma virus causing renal allograft nephropathy. Reduction of immunosuppression with the early recognition of significant BK viral loads in urine and plasma can effectively prevent BKV associated nephropathy (BKVN), however the optimal compartment and frequency of BK viral load measurement post renal transplantation are undetermined. Our purpose was to examine time to detection and viral loads in urine compared to plasma, and establish viral load cut-offs associated with histological BKVN.
  
  
  
  We performed a retrospective analysis of the BKV screening frequency and compartment(s) of 277 adult renal transplant recipients (RTR).
  
  
  
  BKVN was histologically diagnosed in 17 (6.1 %) RTR. In cases where both urine and plasma were tested fortnightly for 6 months (n = 53), BKV was detected in the urine 29 days earlier than plasma. Fortnightly (n = 72) versus 3-monthly (n = 78) testing demonstrated that BKV was detected in the urine significantly earlier (median 63 versus 97 days, p = 0.001) and at a lower level (median 3.27 versus 6.71 log10 c/mL, p < 0.001) with more frequent testing, but this difference was not evident in plasma first detection (80 versus 95 days, p = 0.536) or first positive viral load (3.18 versus 3.30 log10 c/mL, p = 0.603). The optimum cut-off BK viral load for histological diagnosis of BKVN was 4.10 log10 c/mL for the first positive urine, 3.79 log10 c/mL for the first positive plasma, 9.24 log10 c/mL for the peak urine, and 4.53 log10 c/mL for the peak plasma.
  
  
  
  Frequent urinary BK viral load screening for the prevention of BKVN is suggested due to its high sensitivity and earlier detection.
authors.affiliation: Departments of Microbiology and Infectious Diseases, PathWest Laboratory Medicine WA and Fiona Stanley Hospital, Level 1, Path Block, Fiona Stanley Hospital, 102-118 Murdoch Dve, Murdoch, Perth, 6150, Western Australia, Australia. Peter.Boan@health.wa.gov.au.
authors.forename: Peter
authors.initials: P
authors.lastname: Boan
authors.affiliation: Department of Microbiology, PathWest Laboratory Medicine WA, Level 1, Path Block, Fiona Stanley Hospital, 102-118 Murdoch Dve, Murdoch, Perth, 6150, Western Australia, Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Hewison
authors.affiliation: Renal Transplant Unit, Fiona Stanley Hospital, 102-118 Murdoch Dve, Murdoch, Perth, 6150, Western Australia, Australia.
authors.forename: Ramyasuda
authors.initials: R
authors.lastname: Swaminathan
authors.affiliation: Renal Transplant Unit, Fiona Stanley Hospital, 102-118 Murdoch Dve, Murdoch, Perth, 6150, Western Australia, Australia.
authors.forename: Ashley
authors.initials: A
authors.lastname: Irish
authors.affiliation: Renal Transplant Unit, Fiona Stanley Hospital, 102-118 Murdoch Dve, Murdoch, Perth, 6150, Western Australia, Australia.
authors.forename: Kevin
authors.initials: K
authors.lastname: Warr
authors.affiliation: Department of Histopathology, Royal Perth Hospital, GPO Box X2214, Perth, 6000, Western Australia, Australia.
authors.forename: Rajalingam
authors.initials: R
authors.lastname: Sinniah
authors.affiliation: Department of Microbiology, PathWest Laboratory Medicine WA, Level 1, Path Block, Fiona Stanley Hospital, 102-118 Murdoch Dve, Murdoch, Perth, 6150, Western Australia, Australia.
authors.forename: Todd M
authors.initials: TM
authors.lastname: Pryce
authors.affiliation: Department of Microbiology, PathWest Laboratory Medicine WA, Level 1, Path Block, Fiona Stanley Hospital, 102-118 Murdoch Dve, Murdoch, Perth, 6150, Western Australia, Australia.
authors.forename: James
authors.initials: J
authors.lastname: Flexman
mesh_terms: D000328:Adult; D001739:BK Virus / Q000254:growth & development / Q000302:isolation & purification*; D004279:DNA, Viral / Q000032:analysis / Q000097:blood* / Q000652:urine*; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D007674:Kidney Diseases / Q000097:blood / Q000175:diagnosis* / Q000652:urine / Q000821:virology; D016030:Kidney Transplantation / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D027601:Polyomavirus Infections / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000652:urine; D011379:Prognosis; D012189:Retrospective Studies; D012698:Serologic Tests; D066027:Transplant Recipients; D014184:Transplantation, Homologous / Q000009:adverse effects; D014412:Tumor Virus Infections / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000652:urine; D019562:Viral Load / Q000379:methods
chemical_list: D004279:DNA, Viral
keywords: BK viraemia; BK viruria; BK virus nephropathy; Polyoma virus; Renal transplantation