OBJECTIVETo explore the clinical diagnosis of BK virus (BKV) infection in renal transplant recipients.

METHODSUrine and peripheral blood samples were taken from 234 renal transplant recipients for BKV detection with cytological test and real-time PCR.

RESULTSThe occurrence rate of urine decoy cells, BKV viruria and viremia in these patients was 33.3 %, 33.3% and 16.2%, respectively, and the median level of urine decoy cells was 6/10 HPF, with the median level of urine and peripheral blood BKV of 7.62 x 10(3) copy/ml and 7.61 x 10(3) copy/ml, respectively. The positivity rate of BKV in the urine samples were significantly higher than that in peripheral blood samples (P=0.000). The amount of decoy cells was related to BKV load in the urine samples (gamma=0.59, P=0.000), but the BKV load in the urine samples was not related to that in peripheral blood samples (P=0.14).

CONCLUSIONRenal transplantation is associated with increased BKV shedding, indicating the necessity of BKV monitoring in renal transplant recipients with urine cytology, which is convenient and sensitive and indicates renal histological changes indirectly. Urine and peripheral blood BKV DNA detection is of value in identifying BKV activation to prevent irreversible graft damage of BKV-associated nephropathy.

Adolescent ; Adult ; Aged ; BK Virus ; genetics ; isolation & purification ; physiology ; Child ; Child, Preschool ; Female ; Humans ; Kidney Transplantation ; adverse effects ; Male ; Middle Aged ; Polyomavirus Infections ; diagnosis ; virology ; Young Adult

Quantitative measurement of BK virus DNA (Q-BKDNA) has been used for the early diagnosis and monitoring of BK virus-associated nephropathy (BKVAN). This study was designed to determine the BKDNA cutoff for the diagnosis of BKVAN. Between June 2005 and February 2007, 64 renal transplant recipients taken renal biopsies due to renal impairment submitted plasma and urine for Q-BKDNA. Eight BKVAN patients (12.5%) had median viral loads of 6.0 log(10) copies/mL in plasma and 7.3 log(10) copies/mL in urine. Among 56 non-BKVAN patients, 45 were negative for Q-BKDNA; 4 were positive in plasma with a median viral load of 4.8 log(10) copies/ mL, and 10 were positive in urine with a median viral load of 4.8 log(10) copies/mL. Receiver operating characteristic curve analysis showed that a cutoff of 4.5 log(10) copies/mL in plasma and a cutoff of 5.9 log(10) copies/mL in urine had a sensitivity of 100% and a specificity of 96.4%, respectively. A combined cutoffs of 4 log(10) copies/ mL in plasma and 6 log(10) copies/mL in urine had better performance with a sensitivity of 100% and a specificity of 98.2% than each cutoff of urine or plasma. QBKDNA with the combined cutoffs could reliably diagnose BKVAN in renal transplant recipients.
Adolescent ; Adult ; BK Virus/*genetics ; Biopsy ; Calibration ; DNA, Viral/*genetics ; Female ; Humans ; Kidney Diseases/*virology ; Kidney Transplantation/*methods ; Male ; Middle Aged ; Polymerase Chain Reaction ; Polyomavirus Infections/diagnosis ; Treatment Outcome