Prospective monitoring of BK virus replication in renal transplant recipients

BK virus nephropathy developing after renal transplantation and its treatment with ciprofloxacin: a case report

BK virus nephropathy (BKVN) is among the most important problems in renal transplant recipients. This report presented an assessment of treatment with a fluoroquinolone antibiotic, ciprofloxacin, for 6 months in a 21-year-old male patient who developed BKVN after transplantation. Ciprofloxacin treatment reduced the viral load and improved the clinical findings.

Evaluating the impact of pre-transplant desensitization utilizing a plasmapheresis and low-dose intravenous immunoglobulin protocol on BK viremia in renal transplant recipients

BACKGROUND

A correlation exists between polyomavirus BK (BKV) viremia in renal transplant recipients (RTR) and the degree of immunosuppression. However, the impact of pre-transplant desensitization on the incidence of BKV viremia is unknown.

METHODS

This retrospective study evaluated living-donor RTR between January 2004 and December 2008 receiving routine BKV viral load monitoring. Patients were divided into those who underwent pre-transplant desensitization (n = 20) and those who did not (n = 71). The primary endpoint was the incidence of BKV viremia at 1 year post transplant.

RESULTS

All demographic data were similar, except for more female patients (65% vs. 36.6%; P = 0.0392) in the desensitized group. More desensitized patients had a previous transplant (75% vs. 12.7%; P < 0.0001) and were more likely to be induced with basiliximab (75% vs. 35.2%; P = 0.0021). Following transplantation, antibody-mediated rejection (AMR) rates were highest in the desensitized group (55% vs. 1.4%; P < 0.0001). The incidence of BKV viremia at 1 year post transplant was significantly higher in desensitized patients (45% vs. 19.7%; P = 0.0385). Desensitization was also associated with a higher prevalence of BKV viremia at any time post transplant (50% vs. 22.5%; P = 0.0245), polyomavirus-associated nephropathy (20% vs. 2.8%; P = 0.0198) and BKV-related allograft loss (10% vs. 0%; P = 0.0464). Also of note, in a subgroup analysis of only our desensitized patients, it did not appear that development of AMR significantly impacted the incidence of BKV viremia in these individuals.

CONCLUSIONS

This analysis reveals that pre-transplant desensitization significantly increases the risk for BKV viremia and nephropathy.

Polyomavirus BK replication in de novo kidney transplant patients receiving tacrolimus or cyclosporine: a prospective, randomized, multicenter study

Polyomavirus BK (BKV)-associated nephropathy causes premature kidney transplant (KT) failure. BKV viruria and viremia are biomarkers of disease progression, but associated risk factors are controversial. A total of 682 KT patients receiving basiliximab, mycophenolic acid (MPA), corticosteroids were randomized 1:1 to cyclosporine (CsA) or tacrolimus (Tac). Risk factors were analyzed in 629 (92.2%) patients having at least 2 BKV measurements until month 12 posttransplant. Univariate analysis associated CsA-MPA with lower rates of viremia than Tac-MPA at month 6 (10.6% vs. 16.3%, p = 0.048) and 12 (4.8% vs. 12.1%, p = 0.004) and lower plasma BKV loads at month 12 (3.9 vs. 5.1 log(10) copies/mL; p = 0.028). In multivariate models, CsA-MPA remained associated with less viremia than Tac-MPA at month 6 (OR 0.60; 95% CI 0.36-0.99) and month 12 (OR 0.33; 95% CI 0.16-0.68). Viremia at month 6 was also independently associated with higher steroid exposure until month 3 (OR 1.19 per 1 g), and with male gender (OR 2.49) and recipient age (OR 1.14 per 10 years) at month 12. The data suggest a dynamic risk factor evolution of BKV viremia consisting of higher corticosteroids until month 3, Tac-MPA compared to CsA-MPA at month 6 and Tac-MPA, older age, male gender at month 12 posttransplant.

Polyomavirus BK replication in de novo kidney transplant patients receiving tacrolimus or cyclosporine: a prospective, randomized, multicenter study

Polyomavirus BK (BKV)-associated nephropathy causes premature kidney transplant (KT) failure. BKV viruria and viremia are biomarkers of disease progression, but associated risk factors are controversial. A total of 682 KT patients receiving basiliximab, mycophenolic acid (MPA), corticosteroids were randomized 1:1 to cyclosporine (CsA) or tacrolimus (Tac). Risk factors were analyzed in 629 (92.2%) patients having at least 2 BKV measurements until month 12 posttransplant. Univariate analysis associated CsA-MPA with lower rates of viremia than Tac-MPA at month 6 (10.6% vs. 16.3%, p = 0.048) and 12 (4.8% vs. 12.1%, p = 0.004) and lower plasma BKV loads at month 12 (3.9 vs. 5.1 log(10) copies/mL; p = 0.028). In multivariate models, CsA-MPA remained associated with less viremia than Tac-MPA at month 6 (OR 0.60; 95% CI 0.36-0.99) and month 12 (OR 0.33; 95% CI 0.16-0.68). Viremia at month 6 was also independently associated with higher steroid exposure until month 3 (OR 1.19 per 1 g), and with male gender (OR 2.49) and recipient age (OR 1.14 per 10 years) at month 12. The data suggest a dynamic risk factor evolution of BKV viremia consisting of higher corticosteroids until month 3, Tac-MPA compared to CsA-MPA at month 6 and Tac-MPA, older age, male gender at month 12 posttransplant.

Polyomavirus BK replication in de novo kidney transplant patients receiving tacrolimus or cyclosporine: a prospective, randomized, multicenter study

Polyomavirus BK (BKV)-associated nephropathy causes premature kidney transplant (KT) failure. BKV viruria and viremia are biomarkers of disease progression, but associated risk factors are controversial. A total of 682 KT patients receiving basiliximab, mycophenolic acid (MPA), corticosteroids were randomized 1:1 to cyclosporine (CsA) or tacrolimus (Tac). Risk factors were analyzed in 629 (92.2%) patients having at least 2 BKV measurements until month 12 posttransplant. Univariate analysis associated CsA-MPA with lower rates of viremia than Tac-MPA at month 6 (10.6% vs. 16.3%, p = 0.048) and 12 (4.8% vs. 12.1%, p = 0.004) and lower plasma BKV loads at month 12 (3.9 vs. 5.1 log(10) copies/mL; p = 0.028). In multivariate models, CsA-MPA remained associated with less viremia than Tac-MPA at month 6 (OR 0.60; 95% CI 0.36-0.99) and month 12 (OR 0.33; 95% CI 0.16-0.68). Viremia at month 6 was also independently associated with higher steroid exposure until month 3 (OR 1.19 per 1 g), and with male gender (OR 2.49) and recipient age (OR 1.14 per 10 years) at month 12. The data suggest a dynamic risk factor evolution of BKV viremia consisting of higher corticosteroids until month 3, Tac-MPA compared to CsA-MPA at month 6 and Tac-MPA, older age, male gender at month 12 posttransplant.

Early monitoring of the human polyomavirus BK replication and sequencing analysis in a cohort of adult kidney transplant patients treated with basiliximab

Background

Nowadays, better immunosuppressors have decreased the rates of acute rejection in kidney transplantation, but have also led to the emergence of BKV-associated nephropathy (BKVAN). Therefore, we prospectively investigated BKV load in plasma and urine samples in a cohort of kidney transplants, receiving basiliximab combined with a mycophenolate mofetil-based triple immunotherapy, to evaluate the difference between BKV replication during the first 3 months post-transplantation, characterized by the non-depleting action of basiliximab, versus the second 3 months, in which the maintenance therapy acts alone. We also performed sequencing analysis to assess whether a particular BKV subtype/subgroup or transcriptional control region (TCR) variants were present.

Methods

We monitored BK viruria and viremia by quantitative polymerase chain reaction (Q-PCR) at 12 hours (Tx), 1 (T1), 3 (T2) and 6 (T3) months post-transplantation among 60 kidney transplant patients. Sequencing analysis was performed by nested-PCR with specific primers for TCR and VP1 regions. Data were statistically analyzed using χ² test and Student's t-test.

Results

BKV was detected at Tx in 4/60 urine and in 16/60 plasma, with median viral loads of 3,70 log GEq/mL and 3,79 log GEq/mL, respectively, followed by a significant increase of both BKV-positive transplants (32/60) and median values of viruria (5,78 log GEq/mL) and viremia (4,52 log GEq/mL) at T2. Conversely, a significantly decrease of patients with viruria and viremia (17/60) was observed at T3, together with a reduction of the median urinary and plasma viral loads (4,09 log GEq/mL and 4,00 log GEq/mL, respectively). BKV TCR sequence analysis always showed the presence of archetypal sequences, with a few single-nucleotide substitutions and one nucleotide insertion that, interestingly, were all representative of the particular subtypes/subgroups we identified by VP1 sequencing analysis: I/b-2 and IV/c-2.

Conclusions

Our results confirm previous studies indicating that BKV replication may occur during the early hours after kidney transplantation, reaches the highest incidence in the third post-transplantation month and then decreases within the sixth month, maybe due to induction therapy. Moreover, it might become clinically useful whether specific BKV subtypes or rearrangements could be linked to a particular disease state in order to detect them before BKVAN onset.

BK Virus in Kidney Transplant Recipients: The Influence of Immunosuppression

The incidence of BK virus infection in kidney transplant recipients has increased over recent decades, coincident with the use of more potent immunosuppression. More importantly, posttransplant BK virus replication has emerged as an important cause of graft damage and subsequent graft loss. Immunosuppression has been accepted as a major risk for BK virus replication. However, the specific contribution of individual immunosuppressive medications to this risk has not been well established. The purpose of this paper is to provide an overview of the recent literature on the influence of the various immunosuppressant drugs and drug combinations on posttransplant BK virus replication. Evidence supporting the various immunosuppression reduction strategies utilised in the management of BK virus will also be briefly discussed.

Prospective monitoring of BK virus reactivation in renal transplant recipients in North India

BACKGROUND

BK nephropathy (BKN) is an important complication of renal transplantation with a reported incidence between 1% and 10% in different parts of the world. Early diagnosis is important to plan early therapeutic strategies. The epidemiology and evolution of BKN is relatively unknown in India and hence, the present study has been designed to prospectively monitor the activation of BK virus (BKV) in renal transplant recipients in India.

PATIENTS AND METHODS

In this study, 32 renal allograft recipients were prospectively monitored with protocol biopsies of allografts, BKV DNA load in plasma, and viral particles in urine by electron microscopy (EM) on day 1, and at 1, 3, and 6 months. Additionally, the baseline BKV DNA load in plasma was quantitated in 21 corresponding donors.

RESULTS

On follow-up in 32 recipients, 9.7%, 23.8%, 19.2%, and 13.3% of patients showed viral profiles by EM at day 1, 1 month, 3 months, and 6 months, respectively. BKV DNA positivity in plasma was 25.8%, 42.9%, 15.4%, and 20% at day 1, 1 month, 3 months, and 6 months, respectively, with mean BKV copy number/mL plasma of 1796, 1029, 2611, and 3318, respectively. A total of 15.7% (17/108) urine samples of 32 renal recipients were positive by urine EM. Out of 100 protocol biopsies, none developed histologically demonstrable cytopathic effects of BKN, although 8% biopsies were SV-40 large T antigen (SV-40 T Ag) positive. By quantitative real-time polymerase chain reaction assay, 27/108 (25%) of recipients' plasma samples were positive for BKV. Peak viremia and viruria occurred at 1-3 months post transplantation. The baseline viremia in donors was predictive of viremia positivity in the post-transplantation period at 1 month. Twenty-four episodes of graft dysfunction were attributed mainly to rejection.

CONCLUSION

The study shows a total of 15.7% and 25% urine and plasma samples were positive for BKV at any time during a 6-month follow-up. The highest incidence of BK viruria and viremia occurred at 1 month. In protocol biopsies, focal positivity of SV-40 T Ag was seen in 8% biopsies.

Infection and chronic allograft dysfunction

With the advent of more potent immunosuppressive regimens, the incidence of acute rejection following renal transplantation has declined sharply in recent years. In spite of this, long-term graft outcomes remain suboptimal because of relentless attrition by cumulated insults to the allograft. As acute rejection rates have declined, other causes of graft injury and loss have recently emerged. Among these, infectious diseases remain a persistent threat and can be associated with allograft dysfunction. This group includes nephropathy due to polyoma (BK) virus infection, cytomegalovirus disease, and bacterial infection (the latter most commonly arising from the urinary tract). Rarer infectious causes of chronic allograft dysfunction include cryoglobulinemia associated with hepatitis C, Epstein-Barr virus-associated posttransplant lymphoproliferative disease, and direct cytotoxicity from adenoviral infection or parvovirus B19.

Serial measurements of hepatitis C viral load by real-time polymerase chain reaction among recipients of living-donor renal transplants: a short-term follow-up study from a single center

There is a high prevalence of hepatitis C virus (HCV) infection among immunosuppressed patients including renal transplant recipients. The study investigated serum viral loads for up to 6 months posttransplantation among these patients. Serum viral load was serially monitored using real-time polymerase chain reaction (PCR) in 25 HCV-positive renal transplant recipients pretransplantation as well as day 10 and 6 months posttransplantation. A liver biopsy specimen obtained under vision at the time of transplantation was analyzed for viral load as well as for histological changes. There was increased viremia at day 10 followed by a significant (2 log) reduction at 6 months posttransplantation. Pretransplantation serum and intrahepatic viral load showed significant positive correlations (r = 0.727; P = .001), the latter also reflecting liver fibrosis score (r = 0.423; P = .05). The findings suggested that serum viral load reflects intrahepatic viral load, which in turn correlates with liver fibrosis. At 6 months posttransplantation, the modulatory effects of immunosuppressive drugs and of the host immune response may lead to a reduced viral load.

Anti-BK virus mechanisms of sirolimus and leflunomide alone and in combination: toward a new therapy for BK virus infection

BACKGROUND

Human BK polyomavirus is the causative agent of BK nephropathy which is now the leading cause of early renal graft loss. Although no randomized clinical trials have supported this therapy, reduction of immunosuppressive drugs is the current BK nephropathy treatment. We hypothesized that inhibition of the intracellular protein kinase pathways activated by BK virus may be a more effective therapeutic strategy than reduction of immunosuppression.

METHODS AND RESULTS

Four days after infection of renal epithelial cells lines CCD1103, CCD1105 and human primary tubular epithelial cells with BK virus, we found increased phosphorylation of 3'-phosphoinositide-dependent kinase-1 (PDK-1), the protein kinase Akt (Akt), mammalian target of rapamycin (mTOR), and 70 kDa ribosomal protein S6 kinase (p70S6K). To inhibit this pathway, we used sirolimus, which repressed p70S6K phosphorylation and reduced BK virus large T antigen expression in a dose-dependent manner. We then used the tyrosine kinase inhibitor leflunomide (using the active metabolite A77 1726), which decreased PDK1 and Akt phosphorylation and inhibited BK virus genome replication and early gene expression. The combination of sirolimus and leflunomide inhibited BK virus genome replication, large T antigen expression, PDK1, Akt, mammalian target of rapamycin, and p70S6K phosphorylation.

CONCLUSIONS

On the basis of these results, we suggest that inhibition of protein kinase pathways with a combination of sirolimus and leflunomide may be an effective therapy for BK virus reactivation. Because both sirolimus and leflunomide possess immunosuppressive activity, combination therapy may reduce BK pathogenesis while maintaining appropriate transplant immunosuppression.

Evaluation of fluoroquinolones for the prevention of BK viremia after renal transplantation

BACKGROUND AND OBJECTIVES

Nearly 30% of renal transplant recipients develops BK viremia, a prerequisite for BK nephropathy. Case reports have evaluated treatment options for BK virus, but no controlled studies have assessed prophylactic therapies. Fluoroquinolone antibiotics were studied for prevention of BK viremia after renal transplantation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective analysis evaluated adult renal transplant recipients with at least one BK viral load (blood) between 90 and 400 days after transplantation. Six to 12 months of co-trimoxazole was used for Pneumocystis prophylaxis. In sulfa-allergic/-intolerant patients, 6 to 12 months of atovaquone with 1 month of a fluoroquinolone was used. Fluoroquinolones can inhibit BK DNA topoisomerase. The two groups studied were those that received 30 days of levofloxacin or ciprofloxacin after transplantation and those that did not. The primary endpoint was BK viremia rates at 1 year. Of note, of the 160 patients not receiving fluoroquinolone prophylaxis, 40 received a fluoroquinolone for treatment of a bacterial infection within 3 months after transplantation. Subgroup analysis evaluating these 40 patients against the 120 who had no exposure to fluoroquinolones was completed.

RESULTS

A 1-month fluoroquinolone course after transplantation was associated with significantly lower rates of BK viremia at 1 year compared with those with no fluoroquinolone. In the subgroup analysis, exposure to fluoroquinolone for treatment of bacterial infections within 3 months after transplantation was associated with significantly lower 1-year rates of BK viremia.

CONCLUSIONS

This analysis demonstrates that fluoroquinolones are effective at preventing BK viremia after renal transplantation.

A suppressive effect of cyclosporine A on replication and noncoding control region activation of polyomavirus BK virus

BACKGROUND

The effect of cyclosporine A (CsA) on polyomavirus BK virus (BKV) replication remains unclear. The aim of this in vitro study was to investigate the effect of CsA on BKV replication in human uroepithelial cells.

METHODS

After infection of a human renal proximal tubular cell line, HK-2 with BKV, BKV viral load in the presence of CsA was assessed by real-time polymerase chain reaction. The BKV large T-antigen (LTag) expression was measured by Western blot analysis. The BKV early promoter activity was determined by measuring luciferase activity of the BKV noncoding control region luciferase reporter. The BKV LTag expression in a human bladder carcinoma cell line, T24, was assessed by immunofluorescence.

RESULTS

The results demonstrated that the increased levels of BKV LTag and viral protein 1 transcripts measured by real-time polymerase chain reaction were suppressed by CsA in a dose-dependent manner (0.5-4 microg/mL). Western blot analysis also showed that CsA inhibited BKV LTag expression. In addition, the activity of the BKV early promoter, which was enhanced by BKV LTag overexpression, was abrogated by CsA. Finally, the suppressive effect of CsA on BKV replication was also shown in T24 cells as CsA reduced immunofluorescent staining of BKV LTag in these cells.

CONCLUSION

This in vitro study indicates that CsA suppresses BKV replication in human proximal renal tubular cells and uroepithelial cells of the urinary bladder and inhibits the BKV-LTag-regulated increase in early promoter activity.

Update on human polyomavirus BK nephropathy

Polyomavirus BK (BKV) has ebeen identified as the main cause of polyomavirus-associated nephropathy, a major cause of renal allograft failure. Although BKV-associated nephropathy develops in only 2% to 5% of renal transplant recipients, its prognosis when present is very poor, with irreversible graft failure developing in 45% of affected patients. While the use of urine cytology for the detection of decoy cells has been in use for decades, other diagnostic modalities to detect BKV have emerged, including tissue biopsy, polymerase chain reaction, viral culture, and serology. Currently, there is no consensus regarding the laboratory technique best suited for clinical monitoring. This review article will discuss essential and clinical features of polyomavirus, followed by a discussion pertaining to the various diagnostic modalities that contribute to detecting polyomavirus-associated nephropathy.

Maintenance immunosuppressive agents as risk factors for BK virus nephropathy: a case-control study

BACKGROUND

The specific role of different immunosuppressive agents as risk factors for BK virus nephropathy (BKN) has not been well studied.

METHODS

In this case-control study, we examined the association of tacrolimus (TAC), mycophenolate mofetil (MMF), and prednisone with BKN in renal allograft recipients transplanted between 1997 and 2004 at our center who underwent biopsies for allograft dysfunction. Drug levels or doses were recorded during the 3 months before the index biopsy. Random effects logistic modeling was used for data analysis.

RESULTS

There were 33 cases with BKN, biopsied at 16.4+/-2.8 months and 66 matched controls with biopsies at 21.5+/-2.1 months posttransplant (P=0.16). After adjusting for sex, race, retransplant status, diabetes, donor source, and induction agent, TAC blood level was associated with increased risk of BKN (odds ratio [OR] 1.3, 95% confidence interval [CI] 1.02-1.7, P=0.03), whereas MMF dose was not (OR 1.0, 95% CI 0.99-1.0, P=0.2). Moreover, prednisone dose was also found to be a significant risk factor for BKN (OR 1.22, 95% CI 1.04-1.4, P=0.02).

CONCLUSIONS

The results of this study show that BKN is associated with TAC level and prednisone dose and not with MMF dose. This suggests that reducing TAC and prednisone dose and maintaining MMF may be a more appropriate initial approach for the treatment of BKN. Further studies are needed to compare the efficacy and safety of this approach with the currently recommended one.