BK Virus DNA In Plasma Research Articles

P1605THE EARLY RISE OF URINARY EXOSOMAL BK VIRUS MICRORNA AS A PREDICTIVE MARKER FOR BK VIRUS NEPHROPATHY IN A PROSPECTIVE KIDNEY TRANSPLANTATION COHORT

Abstract Background and Aims BK virus nephropathy (BKVN) is one of the significant contributors to allograft dysfunction in kidney transplantation. Because of the lack of effective anti-viral medication, early detection of BKV replication and preemptive management is vital to preserving allograft function. Herein, we investigated the predictive value of urinary exosomal BKV-microRNA for BKVN in the kidney transplantation cohort. Method ARTKT (assessment of immunologic risk and tolerance in kidney transplantation) is a prospective observational cohort in which a total of 420 kidney transplant recipients were enrolled from 7 teaching hospitals in South Korea since 2015. Urine samples were collected at 0.5, 3, 6, 12, and 24 months after kidney transplantation in this cohort. All enrolled patients were reviewed to identify the patients diagnosed with BKVN histologically (biopsy-proven BKVN) and those experienced BK viremia defined as plasma BKV DNA load > 4 log10 copies per mL (presumptive BKVN). Urinary exosomal miR was quantified using real-time reverse transcription PCR. Results 10 patients and 14 patients developed biopsy-proven BKVN and presumptive BKVN, respectively. Because of unavailable urine samples, urinary exosomal BKV-microRNA was investigated in 8 patients with biopsy-proven BKVN and 13 patients with presumptive BKVN. 61 patients with no evidence of BKVN were selected as a negative control. Most of BKVN was developed in a median time of 3.4 months after transplantation. In line with this pattern, urinary exosomal BKV-microRNA peaked at 3 months after transplantation and decreased thereafter in biopsy-proven BKVN and presumptive BKVN, keeping higher value in biopsy-proven BKVN compared to presumptive BKVN after 3 months. At 2 weeks after transplantation, half of the patients with biopsy-proven BKVN showed an early rise of urinary exosomal BKV-microRNA, whereas patients with presumptive BKVN and no evidence of BKVN did not. However, plasma BK virus DNA was not detected in all groups at 2 weeks after transplantation. In multivariate cox proportional hazards model, urinary exosomal BKV-microRNA was significantly associated with biopsy-proven BKVN. Conclusion A urinary exosomal BKV-microRNA increase as early as 2 weeks after kidney transplantation predicts future BKVN development, enabling early intervention.

The clinical significance of BK viremia and the effect of cyclosporine and/or mizoribine on BK virus infection

IntroductionThe diagnosis of BK virus nephropathy is based on renal biopsy findings, and the diagnosis of presumptive BK virus nephropathy is made by sustained plasma BK virus DNA loads of > 4 log10 copies/ml. However, the BK virus plasma viral load cutoff of 4 log10 copies/ml may underestimate the diagnosis of BK virus nephropathy. In this study, we evaluated the clinical significance of BK viremia in kidney transplant recipients. Patients and MethodsFrom January 2010 to November 2015, we experienced 8 kidney transplant recipients who developed BK viremia. We retrospectively analyzed these recipients, focusing on the plasma BK viral load at onset of BK viremia, time to BK viremia after transplantation, frequency of BK virus nephropathy, and our treatment for BK viremia. ResultsThe median plasma BK virus polymerase chain reaction at the diagnosis of BK viremia was 1600 copies/ml (370–9400 copies/ml). The median time to BK viremia after transplantation was 10.9 months (1.4–67.9 months). Three patients were associated with BK virus nephropathy on biopsy. Clearance of BK viremia was observed in all of these cases after intervention. ConclusionsOur study demonstrated that intervention in BK viremia with a viral load of < 4 log10 copies/ml may be needed to prevent the development of graft dysfunction and BK virus nephropathy in kidney transplant recipients.

Frequency and subtype of BK virus infection in Iranian patients infected with HIV.

Human polyomavirus BK virus (BKV) is a double-stranded DNA virus that infects approximately 90 % of the general population as a subclinical or mild infection. In immunosuppressed patients, such as HIV cases, BKV may be reactivated resulting hemorrhagic cystitis and tubulointerstitial nephritis. However, there are limited studies on prevalence and molecular epidemiology of BKV in Iran. We therefore aimed to evaluate the prevalence and subtypes of BKV in Iranian HIV patients. A total of 99 patients with HIV infection were enrolled in the study. Presence of BKV DNA in plasma was evaluated by nested PCR. PCR products were sequenced directly, and phylogenetic analysis was performed. BKV DNA was detected in 8.08 % of HIV patients. BKV viremia presented in 4 out of 25 patients (16 %) not receiving antiretroviral therapy in comparison with 4 out 74 of HAART-treated patients (5.4 %) (P = 0.023). In patients with CD4 counts ≥200 cells/mm(3), viremia was found more commonly (7/80 = 8.8 %) than in those with lower counts (1/19 = 5.2 %) (not significant). All sequenced BKV isolates belonged to subtype Ib-2. Our findings indicated that the prevalence of BKV viremia is relatively prevalent in patients with HIV infection and significantly higher in naïve than HAART-treated cases. Therefore, HAART can eliminate BKV infection from plasma and reduce viremia although the actual implication of BKV viremia in HIV patients is not clear.

A Prospective Study on the Predictive Value of Plasma BK Virus-DNA Load for Hemorrhagic Cystitis in Pediatric Patients After Stem Cell Transplantation.

In hematopoietic stem cell transplantation (HSCT), late hemorrhagic cystitis (HC) has been associated with BK virus (BKV) infection. We assessed the value of plasma BKV load in predicting HC. Plasma and urine BKV-DNA load were assessed prospectively in 107 pediatric patients. Twenty patients developed grade II and III HC, with 100-day cumulative incidence of 18.8%. At diagnosis of HC, the median load of BKV DNA was 2.3 × 10(3) copies/mL. A plasma BKV-DNA load of 10(3) copies/mL had a sensitivity of 100% and a specificity of 86% with a negative predictive value (NPV) of 100% and a positive predictive value (PPV) of 39% for HC. A urine BKV-DNA load of >10(7) copies/mL had a sensitivity of 86% and a specificity of 60% with a NPV of 98% and a PPV of 14% for HC. A BKV load of 10(3) copies/mL on plasma was significantly associated with HC in multivariate analysis (hazard ratio [HR], 6.1; P = .0006). Patients with HC had a significantly higher risk of mortality than patients who did not have HC (HR, 2.6; P = .018). The above values were used to monitor plasma BKV-DNA load, and they provided a better prediction of patients at risk of HC than urine BKV-DNA load.

Early Disappearance of Urinary Decoy Cells in Successfully Treated Polyomavirus BK Nephropathy

BackgroundPolyomavirus BK nephropathy (BKVN) is an important infectious complication in kidney transplant patients. Regular screening using polymerase chain reaction for BK virus DNA in plasma and urinary cytology is effective for early diagnosis of BKVN. However, methods of follow-up and therapeutic targets are not well described. MethodsTen patients with BKVN who received biweekly urinary cytology and repeat biopsies after diagnosis were retrospectively studied. Histological remission of BKVN was determined when biopsy revealed negative SV40 large T-antigen (TAg) staining. Results of urinary cytology and repeat biopsy findings were compared. ResultsUrinary decoy cells disappeared in 8 of 10 patients 55 ± 25 (range 13–79) days after index biopsies. In those cases, allograft function was preserved and the final serum creatinine level was 2.14 ± 1.19 (0.80–4.55) mg/dL after 962 ± 393 (325–1563) days of follow-up. Two cases with persistent urinary decoy cells shedding lost their graft 195 and 362 days later. Amongst 29 repeat biopsies, there were 13 TAg-positive and 16 negative biopsies. In 12 of 13 TAg-positive biopsies (92%), urinary decoy cells were still positive, whereas at the same time in 15 TAg-negative biopsies, decoy cells had already disappeared (94%). ConclusionsCytology testing is advantageous because of its cost effectiveness. Clearance of decoy cells from urine was closely related to histological remission of BKVN, and may possibly be a therapeutic target in BKVN.

Management and Outcome of BK Viremia in Renal Transplant Recipients

BK viremia can lead to nephritis, which can progress to irreversible kidney transplant failure. Our prospective study provides management and outcome of BK viremia in renal transplant recipients. Two hundred forty de novo kidney-only recipients were enrolled from July 2007 to July 2010 and followed for 1 year. Standard immunosuppression with Thymoglobulin/interleukin 2 receptor blocker and mycophenolate mofetil/tacrolimus (Tac)/prednisone was employed. Quantitative BK virus (BKV) DNA surveillance in plasma/urine was performed at 1, 3, 6, 12, and 24 months after transplantation. Patients with significant viremia (defined as ≥10,000 viral copies/mL) underwent renal biopsy and treated with 30% to 50% reduction in doses of both mycophenolate mofetil and Tac without antiviral therapy. The target 12-hr Tac trough levels were lowered to 4 to 6 ng/mL in the significant viremia group, whereas the target levels remained unchanged at 5 to 8 ng/mL for all other groups. Sixty-five patients (27%) developed BK viremia; 28 (12%) of whom had significant viremia. A total of five (21%) of the 23 (of 28) patients who underwent biopsy presented with subclinical BKV nephritis. The mean plasma BKV DNA declined by 98% (range, 76%-100%) at 1 year after peak viremia. Acute cellular rejection seen in four (14%) of 28 patients, responded to bolus steroids. There was no decline in estimated glomerular filtration rate over time from 1 month after transplantation to 1 year after peak viremia (P=0.57). Reduction in immunosuppression alone resulted in the successful resolution of viremia with preservation of renal function and prevention of clinical BKV nephritis and graft loss.

BK virus viremia in a well‐HLA‐matched kidney transplant population mainly on low‐dose cyclosporine‐based immunosuppression

The incidence and clinical course of polyomavirus-associated nephropathy (PyVAN) in our well-HLA-matched kidney transplant population mainly on low-dose cyclosporine-based triple-drug immunosuppression has not been described in detail. We aimed to characterize our patients with PyVAN and BK virus (BKV) viremia. Among 166 kidney transplantations between January 2007 and February 2011 followed up at Helsinki University Hospital nephrology clinic, 136 were screened for BKV viremia by quantitative analysis of BKV DNA in plasma. PyVAN was diagnosed by biopsy histopathology and SV40 T-antigen detection. BKV viremia or PyVAN were treated by reducing immunosuppression. BKV viremia was detected in 12 (9%) patients. PyVAN was diagnosed in six patients (4%). In the six patients with no PyVAN, four had low-level viremia (<10,000 copies/mL) of short duration (<2 months), one had high-level viremia, and one had sustained low-level viremia. After reduction of immunosuppression, all except one patient were able to clear viremia. No grafts were lost due to PyVAN. Even in a low-risk population, BKV viremia and PyVAN occur, highlighting the importance of monitoring viral loads. Reduction of immunosuppression was successful, and no grafts were lost due to PyVAN.

BK virus nephropathy: Clinical experience in a university hospital in Japan

To review the medical records of patients with BK virus nephropathy (BKVN) following kidney transplantation in our institution. We screened patients for decoy cells using urine cytology, assessed serum creatinine levels, and conducted a graft biopsy, as well as assessed the presence of plasma BK virus DNA by quantitative real-time polymerase chain reaction. The treatment of BKVN was based on the decreased use of immunosuppressants. Overall, six male patients were studied (mean age 40.8 years, range 18-58; mean donor age 45.2 years, range 15-67). A positive urine cytology screen led to the subsequent detection of plasma BK virus DNA in the five patients with urine cytology results positive for decoy cells. In the four patients in whom plasma BK virus DNA was detected, a maximum value of DNA of > or = 10 000 copies/mL was observed. Time elapsed from transplantation to BKVN diagnosis ranged from 3 to 62 months. Although the two cadaver grafts were lost, the loss was not due to any effects directly associated with BKVN. The other four grafts are still functioning with a mean creatinine level of 1.8 mg/dL. Most of the patients with BKVN were regarded as being in a state of heightened immunosuppression. BK virus transition to blood was prevented in one patient. Early diagnosis of BKV infection with reduction of immunosuppression may potentially counter BK viremia and retard progression of BKV nephropathy. Decoy cell screening by urine cytology as well as plasma BK virus DNA screening should be considered in addition to the required graft biopsy in kidney transplant recipients, particularly in those with impaired graft function.

BK virus nephropathy in an immunodeficient patient with chronic lymphocytic leukemia

Background BK virus, genus polyomavirus, is known as an important cause of nephropathy (BKVN) in renal transplant patients. Cases of BKVN in native kidneys are rare. Objectives To report a case of BKVN in a patient with chronic lymphocytic leukemia (CLL) and to examine viral and immune parameters. Study design Quantitative BK virus DNA in plasma and relevant immune parameters were recorded in one CLL patient with BKVN and ten consecutive CLL patients without BKVN. Results BKVN in the native kidneys of a CLL patient was histologically confirmed. The presence of BKVN correlated with immunologic parameters as well as factors known to cause renal tissue injury. BK viral load levels in the patient steadily increased and exceeded those of the control CLL patients. Conclusions The results document a pathogenic role for BK virus in native kidneys of immuno-compromised CLL patients and indicate a role for quantitative BK virus DNA detection for early management of BKVN in native kidneys.

Successful Treatment of BK Viremia Using Reduction in Immunosuppression Without Antiviral Therapy

Treatment of BK virus (BKV) infection in renal transplant recipients remains controversial. This retrospective analysis evaluated efficacy and safety of reducing immunosuppression without antiviral therapy. This single center analysis included 24 patients diagnosed with BK viremia between September 2001 and December 2003. Sixteen patients (66%) presented with BKV nephritis and eight patients (34%) presented with viremia without evidence of nephritis on renal biopsy. At time of diagnosis, mean plasma BKV DNA (copies/mL) was 460,409 (range 10,205-1,920,691). Mean doses reduction of mycophenolate mofetil and tacrolimus were 44% and 41%, respectively, from time of diagnosis of BKV infection to complete resolution of viremia. A decline in BK viral load was noticed within 15 to 30 days, with successful elimination of viremia over a mean period of 5.8 months (range, 1-9.5). Mean serum creatinine at time of diagnosis of BK viremia was 1.8 mg/dL (range, 1.2-2.8). Mean follow-up period is 30.9 months postdiagnosis. At the most recent visit, serum creatinine was 2.0 mg/dL (range, 1.0-3.6) (P=0.14). With reduction in immunosuppressive therapy, three patients (13%) developed acute cellular rejection and were treated successfully with intravenous bolus steroids. During follow-up, one patient had a relapse of BKV nephritis during pregnancy and lost her graft. After mean follow-up period of 43.5 months posttransplantation, all 24 patients are alive and 23 have a functioning graft. Seventeen patients (71%) have stable or improved graft function. Our analysis shows that reduction in immunosuppression therapy alone results in clearance of the BK viremia with good long-term outcome.

Testing for polyomavirus type BK DNA in plasma to identify renal-allograft recipients with viral nephropathy.

Reactivation of polyomavirus type BK (BK virus) is increasingly recognized as a cause of severe renal-allograft dysfunction. Currently, patients at risk for nephropathy due to infection with the BK virus are identified by the presence of cells containing viral inclusion bodies ("decoy cells") in the urine or by biopsy of allograft tissue. In a retrospective analysis, we performed polymerase-chain-reaction assays for BK virus DNA in plasma samples from 9 renal-allograft recipients with BK virus nephropathy; 41 renal-allograft recipients who did not have signs of nephropathy, 16 of whom had decoy cells in the urine; and as immunocompromised controls, 17 patients who had human immunodeficiency virus type 1 (HIV-1) infection (stage C3 according to the classification of the Centers for Disease Control and Prevention) and who had not undergone transplantation. In all nine patients with BK virus nephropathy, BK virus DNA was detected in the plasma at the time of the initial histologic diagnosis (a mean [+/-SD] of 46+/-28 weeks after transplantation) and during the course of histologically diagnosed, persistent BK virus disease. In three of the six patients with nephropathy who were studied serially after transplantation, BK virus DNA was initially undetectable but was detected 16 to 33 weeks before nephropathy became clinically evident and was confirmed by biopsy. Tests for BK virus DNA in plasma became negative and the nephropathy resolved after the doses of immunosuppressive drugs were decreased in two patients and after removal of the renal allograft in three patients. BK virus DNA was found in the plasma of only 2 of the 41 renal-allograft recipients who had no signs of nephropathy and in none of the patients with HIV-1 infection. Testing for BK virus DNA in plasma from renal-allograft recipients with use of the polymerase chain reaction is a sensitive and specific method for identifying viral nephropathy.