Longitudinal study of BK Polyomavirus outcomes, risk factors, and kinetics in renal transplantation patients

Risk factors for BK virus infection in DCD donor kidney transplant recipients

Background

BK virus infection after kidney transplantation can negatively impact the prognosis of patients. However, current risk factor analyses primarily focus on BK virus nephropathy, while BK viruria and BK viruria progressing to BK viremia receive less attention. This study aims to analyze the risk factors associated with BK viruria and BK viruria progressing to BK viremia in recipients of donation after cardiac death (DCD), with the goal of facilitating early intervention.

Methods

Donor characteristics and clinical data of recipients before and after transplantation were evaluated, and logistic univariate and multivariate analyses were performed to determine the risk factors associated with BK viruria and the progression of BK viruria to BK viremia. Additionally, machine learning techniques were employed to identify the top five features associated with BK viruria evolving into BK viremia.

Results

During a median follow-up time of 1,072 days (range 739-1,418), 69 transplant recipients (15.6% incidence rate) developed BK viruria after transplantation, with 49.3% of cases occurring within 6 months post-transplantation. Moreover, 19 patients progressed to BK viremia. Donor age [OR: 1.022 (1.000, 1.045), p = 0.047] and donor procalcitonin (PCT) levels [0.5-10 ng/ml; OR: 0.482 (0.280, 0.828), p = 0.008] were identified as independent risk factors for BK viruria. High BK viruria [OR: 11.641 (1.745, 77.678), p = 0.011], recipient age [OR: 1.106 (1.017, 1.202), p = 0.018], and immunoinduction regimen [ATG; OR: 0.063 (0.006, 0.683), p = 0.023] were independent risk factors for BK viruria progressing to BK viremia. Machine learning analysis confirmed the importance of high BK viruria, recipient age, and immunoinduction regimen (ATG) in predicting the progression of BK viruria to BK viremia.

Conclusion

The development and progression of BK virus in DCD kidney transplant recipients is influenced by multiple factors. Early intervention and treatment could potentially extend the lifespan of the transplanted organ.

IVIg therapy in the management of BK virus infections in pediatric kidney transplant patients

BK virus-associated nephropathy (BKPyVAN) induces kidney allograft dysfunction. Although decreasing immunosuppression is the standard for managing BK virus (BKPyV) infection, this strategy is not always effective. The use of polyvalent immunoglobulins (IVIg) may be of interest in this setting. We performed a retrospective single-center evaluation of the management of BKPyV infection in pediatric kidney transplant patients. Among the 171 patients who underwent transplantation between January 2010 and December 2019, 54 patients were excluded (combined transplant n = 15, follow-up in another center n = 35, early postoperative graft loss n= 4). Thus, 117 patients (120 transplants) were included. Overall, 34 (28%) and 15 (13%) transplant recipients displayed positive BKPyV viruria and viremia, respectively. Three had biopsy-confirmed BKPyVAN. The pre-transplant prevalence of CAKUT and HLA antibodies was higher among BKPyV-positive patients compared to non-infected patients. After the detection of BKPyV replication and/or BKPyVAN, the immunosuppressive regimen was modified in 13 (87%) patients: either by decreasing or changing the calcineurin inhibitors (n = 13) and/or switching from mycophenolate mofetil to mTor inhibitors (n = 10). Starting IVIg therapy was based on graft dysfunction or an increase in the viral load despite reduced immunosuppressive regimen. Seven of 15(46%) patients received IVIg. These patients had a higher viral load (5.4 [5.0-6.8]log vs. 3.5 [3.3-3.8]log). In total, 13 of 15 (86%) achieved viral load reduction, five of seven after IVIg therapy. As long as specific antivirals are not available for the management of BKPyV infections in pediatric kidney transplant patients, polyvalent IVIg may be discussed for the management of severe BKPyV viremia, in combination with decreased immunosuppression.

Treatment of BK virus with a stepwise immunosuppression reduction and intravenous immunoglobulin in pediatric kidney transplant

BACKGROUND

BKV and BKVN are common in pediatric kidney transplant, but there is limited data on treatment approaches. Our objective was to study the prevalence of BKV and BKVN utilizing only plasma qPCR and report treatment outcomes with stepwise IR and IVIG.

METHODS

A retrospective study of all pediatric kidney transplants from 2013 to 2020. Excluded patients >21 years at transplant and immediate graft failure. Surveillance was conducted using only plasma BK qPCR at 1, 3, 6, 9, 12, 18, and 24 months and annually. BKV defined as ≥250 copies/ml and resolution as <250 copies/ml. Presumed BKVN as >10 000 copies/ml despite IR; and BKVN if confirmed on histology.

RESULTS

Fifty-six patients were included in the study; 20 (35.7%) had BKV. BKV was associated with longer duration of stent, 40 vs. 33.5 days (p = .004). Two patients (3.5%) had confirmed, and 2(3.5%) had presumed BKVN. The first-line treatment was IR in 100% of patients. BKVN confirmed and presumed received IVIG every month for six doses. Viral resolution was achieved in 70%, and no difference was noted in estimated glomerular filtration rate between BKV and non-BKV group (p = .438). There were no rejection episodes, and graft survival was 100% over median follow-up of 3 years.

CONCLUSIONS

Plasma qPCR alone is adequate for screening and monitoring treatment of BKV and BKVN. A stepwise IR and IVIG resulted in BKV resolution in the majority of patients. Larger studies are required to study the role of IVIG in the treatment of BKVN.

Economic Evaluation of Screening for Polyomavirus Infection in Kidney Transplant Recipients: A Cost-Utility Analysis

Screening for polyomavirus infection after kidney transplantation is recommended by clinical practice guidelines, but cost-effectiveness of this strategy is uncertain. The aim of this study was to estimate the incremental costs and benefits of routine screening for polyomavirus infection compared with no screening in kidney transplant recipients.

BK Virus and Cytomegalovirus Coinfections in Kidney Transplantation and Their Impact on Allograft Loss

We aimed to ascertain the interaction and effects of combined reactivations of BK virus and cytomegalovirus on kidney graft function. All consecutive kidney transplant recipients (KTR) between 2003 and 2016 were included. Of 1976 patients who received a kidney transplant, 23 (1.2%) presented BKV-associated nephropathy (BKVAN). Factors independently associated with BKVAN were diabetes mellitus (odds ratios (OR) 3.895%, confidence intervals (CI) (1.4-10.5)), acute allograft rejection (OR 2.8 95%, CI (1.1-7.6)) and nephrostomy requirement (OR 4.195%, CI (1.3-13)). Cytomegalovirus infection was diagnosed in 19% of KTR patients. Recipients with BKVAN presented more frequently with cytomegalovirus (CMV) infection compared to patients without BKVAN (39% vs. 19%, p = 0.02). Acute allograft rejection (OR 2.95%, CI (1.4-2.4)) and nephrostomy requirement (OR 2.95%, CI (1.2-3)) were independently associated with CMV infection. Sixteen patients (69%) with BKVAN had graft dysfunction at one-year post-transplant and eight of them (35%) lost their graft. Patients presenting with BKVAN and graft loss presented more frequently a cytomegalovirus infection (OR 2.295%, CI (1.3-4.3)). In conclusion, we found a relation between CMV infection and graft loss in patients presenting BKVAN, suggesting that patients with CMV reactivation should be actively screened for BKV.

Validation of a noninvasive prognostic signature for allograft failure following BK virus associated nephropathy

Identifying kidney transplant recipients at risk for graft failure following BK virus nephropathy (BKVN) may allow personalization of therapy. We have reported that a noninvasive composite signature of urinary cell level of plasminogen activator inhibitor-1(PAI-1) mRNA and serum creatinine level, measured at the time of BKVN diagnosis, is prognostic of graft failure. In this investigation, we determined whether the composite signature is prognostic of graft failure in an independent cohort of 25 patients with BKVN. Of the 25 patients, 8 developed graft failure and 17 did not. We measured urinary cell levels of PAI-1 mRNA, 18S rRNA, and BKV VP1 mRNA at the time of BKVN diagnosis and evaluated clinical parameters including Banff pathology scores, acute rejection, and graft function. The area under the receiver operating characteristic curve for the noninvasive composite signature was 0.95 (P < .001) for prognosticating graft failure. The previously reported threshold of -0.858 predicted graft failure with a sensitivity of 75% and a specificity of 94%. Our current study validates the use of composite signature and the threshold of -0.858 to identify those at risk for graft failure following BKVN diagnosis, and supports future studies utilizing the composite signature score to personalize treatment of BKVN.