title: Monitoring of polyomavirus BK virus viruria and viremia in renal allograft recipients by use of a quantitative real-time PCR assay: one-year prospective study.
abstract: We have developed a real-time quantitative PCR (rt-QPCR) assay to detect and kinetically monitor BK virus viruria and viremia in renal transplant recipients (RTRs). A total of 607 urine and 223 plasma samples were collected from 203 individuals including those with BK virus-associated nephropathy (BKVAN) (n = 8), those undergoing routine posttransplant surveillance (SV) (n = 155), those with nontransplant chronic kidney disease (NT-CKD) (n = 20), and healthy living kidney donors (LD) (n = 20). The rt-QPCR assay was found to be highly sensitive and specific, with a wide dynamic range (2.4 to 11 log(10) copies/ml) and very good precision (coefficient of variation, approximately 5.9%). There was a significant difference in the prevalences of viruria and viremia between the BKVAN (100% and 100%) and SV (23% and 3.9%) groups (P < 0.001). No viruria or viremia was detected in LD or in NT-CKD patients. The median (range) peak levels of BK virus viruria and viremia, in log(10) copies/ml, were 10.26 (9.04 to 10.83) and 4.83 (3.65 to 5.86) for the BKVAN group versus 0 (0 to 10.83) and 0 (0 to 5.65) for the SV group, respectively (P < 0.001). When the BK virus load in the urine was <7.0 log(10) copies/ml, no BK virus viremia was detected. When the BK virus load in the urine reached 7.0, 8.0, 9.0, and > or =10.0 log(10) copies/ml, the corresponding detection of BK virus viremia increased to 20, 33, 50, and 100%, respectively. We propose monitoring of BK virus viruria in RTRs, with plasma BK virus load testing reserved for those with viruria levels of > or =7.0 log(10) copies/ml.
authors.affiliation: Provincial Laboratory for Public Health (Microbiology), University of Alberta Hospital, Edmonton, Alberta, Canada. x.pang@provlab.ab.ca
authors.forename: Xiaoli L
authors.initials: XL
authors.lastname: Pang
authors.forename: Karen
authors.initials: K
authors.lastname: Doucette
authors.forename: Barbara
authors.initials: B
authors.lastname: LeBlanc
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Cockfield
authors.forename: Jutta K
authors.initials: JK
authors.lastname: Preiksaitis
mesh_terms: D001739:BK Virus / Q000302:isolation & purification*; D004279:DNA, Viral / Q000032:analysis; D006801:Humans; D016030:Kidney Transplantation / Q000009:adverse effects*; D016133:Polymerase Chain Reaction / Q000379:methods*; D011446:Prospective Studies; D014184:Transplantation, Homologous; D014556:Urine / Q000821:virology*; D019562:Viral Load; D014766:Viremia / Q000175:diagnosis*
chemical_list: D004279:DNA, Viral