Renal Donor Implication in the Origin of BK Infection: Analysis of Genomic Viral Subtypes

Importance of Follow-Up Biopsies in the Prediction of Renal Allograft Survival Following Polyomavirus-Associated Nephropathy

OBJECTIVES

Allograft biopsy is the gold standard for diagnosing polyomavirus-associated nephropathy. We aimed to establish the effects of histopathologic findings proposed by the Banff Polyomavirus Working Group on graft outcome. We also aimed to understand the clinical importance of follow-up biopsies for patients with polyomavirus-associated nephropathy.

MATERIALS AND METHODS

Our study included 22 patients with polyomavirus-associated nephropathy. All biopsies were classified according to the latest Banff Polyomavirus Working Group classification. Follow-up biopsies of all patients were evaluated in detail.

RESULTS

The mean interval between polyomavirus-associated nephropathy and transplant was 10 ± 1.6 months. Of 22 patients, biopsy revealed stage 1 in 3 (13.6%), stage 2 in 17 (77.3%), and stage 3 in 2 patients (9.1%). Fourteen patients (63.6%) had polyomavirus viral load 3, 5 (22.7%) had polyomavirus viral load 2, and 3 had polyomavirus viral load 1. Among patients included in analyses, 18.2% had antibody-mediated rejection and 27.2% had T-cell-mediated rejection simultaneously with polyomavirus-associated nephropathy. Graft loss increased with increasing polyomavirus-associated nephropathy class and polyomavirus viral load (P = .015 and P = .002, respectively). The mean time of graft survival decreased with increasing degree of tubulitis, interstitial inflammation, plasma infiltration, and neutrophil infiltration. Patients with interstitial fibrosis, glomerular polyoma, and cortical plus medullar involvement showed earlier graft loss. Follow-up biopsies showed that diffuse interstitial fibrosis or persistent inflam-mation negatively influenced graft loss.

CONCLUSIONS

The Banff Polyomavirus Working Group's schema significantly correlated with graft outcome. Early detection of polyomavirus-associated nephro-pathy and subsequent detection of persistent inflammation and interstitial fibrosis and tubular atrophy in follow-up biopsies and modification of immunosuppressive therapy can successfully prevent graft loss.

Detection of BK polyomavirus genotypes to predict the development of BK polyomavirus-associated complications in kidney transplant recipients: A retrospective analysis

OBJECTIVES

This study focused on the role that BK polyomavirus (BKPyV) genotypes can play in the development of BKPyV-associated complications in renal transplant recipients.

METHODS

A retrospective observational study (January 2015 to April 2018) was conducted by analyzing BKPyV genotypes in 180 blood samples with detectable BKPyV viral load (VL) > 1000 copies/mL, from 63 renal transplant recipients. VL and BKPyV genotypes detections were based on real-time PCR (rt-PCR)-specific assays.

RESULTS

Forty-four patients (44/63 [69.8%]) were men, and the median age was 55.0 (interquartile range 49.0-66.0 years). Eleven patients had clinical manifestations (11/63 [17.5%]). The most frequently detected genotypes were I (14/63 [22.2%]) and II (13/63 [20.6%]). Half of the patients (33/63 [52.4%]) had a mixed genotype, most with genotypes I and II (25/33 [75.8%]). Patients with infection by mixed genotypes showed VLs that were detected earlier (in the first year after transplantation) than those with a single genotype (25/33 [75.8%] vs 13/30 [43.3%], P = .009) and demonstrated greater risk of developing clinical manifestations associated with BKPyV (odds ratio 12.609, 95% confidence interval 1.503-105.807). Moreover, patients with first BKPyV VL > 10 000 copies/mL more frequently presented mixed genotypes (12/16 [75.0%] vs 21/47 [44.7%], P = .036).

CONCLUSIONS

The probability of developing clinical manifestations is higher in infections by mixed genotypes. Therefore, the detection of BKPyV genotypes by rt-PCR can provide relevant information to stratify patients' risk of BKPyV-associated complications and guide the clinical management of BKPyV infection in kidney transplant recipients.

Impact of Pretransplant Donor BK Viruria in Kidney Transplant Recipients

BACKGROUND

BK virus (BKV) is a significant cause of nephropathy in kidney transplantation. The goal of this study was to characterize the course and source of BKV in kidney transplant recipients.

METHODS

We prospectively collected pretransplant plasma and urine samples from living and deceased kidney donors and performed BKV polymerase chain reaction (PCR) and immunoglobulin G (IgG) testing on pretransplant and serially collected posttransplant samples in kidney transplant recipients.

RESULTS

Among deceased donors, 8.1% (17/208) had detectable BKV DNA in urine prior to organ procurement. BK viruria was observed in 15.4% (6/39) of living donors and 8.5% (4/47) of deceased donors of recipients at our institution (P = .50). BKV VP1 sequencing revealed identical virus between donor-recipient pairs to suggest donor transmission of virus. Recipients of BK viruric donors were more likely to develop BK viruria (66.6% vs 7.8%; P < .001) and viremia (66.6% vs 8.9%; P < .001) with a shorter time to onset (log-rank test, P < .001). Though donor BKV IgG titers were higher in recipients who developed BK viremia, pretransplant donor, recipient, and combined donor/recipient serology status was not associated with BK viremia (P = .31, P = .75, and P = .51, respectively).

CONCLUSIONS

Donor BK viruria is associated with early BK viruria and viremia in kidney transplant recipients. BKV PCR testing of donor urine may be useful in identifying recipients at risk for BKV complications.

Variable sources of Bk virus in renal allograft recipients

BK virus is the causative agent of polyomavirus-associated nephropathy, a major cause of kidney transplant failure affecting 1%-10% of recipients. Previous studies that investigated the viral source on the kidney recipient pointed that the donor is implicated in the origin of human polyomavirus BK (BKPyV) infection in recipients, but giving the low genetic variability of BKPyV this subject is still controversial. The aim of this study was to determine if BKPyV replicating in kidney recipients after transplantation is always originated from the donor. Urine and blood samples from 68 pairs of living donors and kidney recipients who underwent renal transplantation from August 2010-September 2011 were screened for BKPyV by real time polymerase chain reaction. Only three recipients presented viremia. When both donors and recipients were BKPyV positive, a larger fragment of VP1 region was obtained and sequenced to determine the level of similarity between them. A phylogenetic tree was built for the 12 pairs of sequences obtained from urine and high level of similarity among all sequences was observed, indicating that homology inferences for donor and recipient viruses must be cautiously interpreted. However, a close inspection on the donor-recipient pairs sequences revealed that 3 of 12 pairs presented considerably different viruses and 4 of 12 presented mixed infection, indicating that the source of BKPyV infection is not exclusively derived from the donor. We report that about 60% of the renal recipients shed BKPyV genetically distinct from the donor, confronting the accepted concept that the donor is the main source of recipients' infection.

Impact of donor BK polyomavirus replication on recipient infections in living donor transplantation

BACKGROUND

Multiple risk factors for BK polyomavirus (BKPyV) replication after kidney transplantation have been described. Here, we investigated the impact of living donors' urinary BKPyV shedding and recipients' BKPyV antibody status pre-transplant on BKPyV replication during the first year post-transplantation.

METHODS

We assessed a cohort of living kidney donors and their paired recipients (n = 121). All donors were tested before transplantation, and recipients were tested before and after transplantation for BKPyV viruria and viremia. BKPyV-specific serology was assessed in all recipients at transplantation.

RESULTS

Ten of 121 donors (8.3%) had urinary BKPyV shedding pre-transplant, none had viremia. Overall, 33 (27.3%) recipients developed viruria after transplantation: 7 had received a kidney from a donor with BK viruria (7/10 positive donors) and 26 had received a kidney from a donor without BK viruria (26/111 negative donors; P = .0015). Fifteen (12.4%) recipients developed BK viremia after transplantation: 3 received a kidney from a donor with viruria (3/10 positive donors, 30%) and 12 received a kidney from a donor without viruria (12/111 negative donors, 11%; P = .08). One patient developed proven nephropathy. Ninety-one percent of recipients were seropositive for BKPyV. No relationship between recipients' sero-reactivity at transplantation and post-transplant BKPyV replication was observed. Pre-transplant donor urinary shedding was an independent risk factor for post-transplant BKPyV replication.

CONCLUSION

Screening living kidney donors for BKPyV can identify recipients at higher risk for BKPyV replication after transplantation who may benefit from intensified post-transplant screening and treatment strategies.

Correlation of BK Virus Neutralizing Serostatus With the Incidence of BK Viremia in Kidney Transplant Recipients

BACKGROUND

BK virus (BKV)-associated nephropathy is the second leading cause of graft loss in kidney transplant recipients. Due to the high prevalence of persistent infection with BKV in the general population, it is possible that either the transplant recipient or donor may act as the source of virus resulting in viruria and viremia. Although several studies suggest a correlation between donor-recipient serostatus and the development of BK viremia, specific risk factors for BKV-related complications in the transplant setting remain to be established.

METHODS

We retrospectively determined the pretransplant BKV neutralizing serostatus of 116 donors (D)-recipient (R) pairs using infectious BKV neutralization assays with representatives from the 4 major viral serotypes. The neutralizing serostatus of donors and recipients was then correlated with the incidence of BK viremia during the first year posttransplantation.

RESULTS

There were no significant differences in baseline demographics or transplant data among the 4 neutralizing serostatus groups, with the exception of calculated panel-reactive antibody which was lowest in the D+/R- group. Recipients of kidneys from donors with significant serum neutralizing activity (D+) had elevated risk for BK viremia, regardless of recipient serostatus (D+ versus D-: odd ratio, 5.0; 95% confidence interval, 1.9-12.7]; P = 0.0008). Furthermore, donor-recipient pairs with D+/R- neutralizing serostatus had the greatest risk for BK viremia (odds ratio, 4.9; 95% confidence interval, 1.7-14.6; P = 0.004).

CONCLUSIONS

Donor neutralizing serostatus correlates significantly with incidence of posttransplant BK viremia. Determination of donor-recipient neutralizing serostatus may be useful in assessing the risk of BKV infection in kidney transplant recipients.

Viral Origin, Clinical Course, and Renal Outcomes in Patients With BK Virus Infection After Living-Donor Renal Transplantation

BACKGROUND

BK virus (BKV) nephropathy remains the main cause of renal graft loss after living-donor renal transplantation. The aim of the study was to investigate the source and factors influencing the course of BKV infection.

METHODS

We investigated 214 living donor-recipient pairs. Urine and blood of donors and recipients were tested by qPCR for the presence of BKV DNA before and after transplantation; genotyping of BKV subtypes was performed.

RESULTS

Eighty-five recipients (40%) had posttransplant BK viruria including 61 with additional viremia and 22 with nephropathy. Pretransplant urinary BKV shedding of donor or recipient was a significant risk factor for posttransplant viruria and viremia (OR, 4.52; CI, 2.33-8.77; P < 0.0001) and nephropathy (OR, 3.03; CI, 1.16-7.9; P = 0.02). In the BKV nephropathy group, urine and blood became BKV positive earlier than in the group with viruria and viremia. Renal function was worse in BKV-nephropathy compared with BKV-negative patients beginning at transplantation. Comparing BKV subtypes of donor and recipient before with the subtype of the infected recipient after transplantation, donor-derived transmission was identified in 24 of 28 corresponding pairs. BKV subtype IV had a higher prevalence in recipients with BKV nephropathy than in those with viruria and viremia (P = 0.045).

CONCLUSIONS

Pretransplant urinary BKV shedding of donor and recipient is a risk for posttransplant infection. Donor-derived BKV transmission is an important mode of infection. BKV subtype IV may be one of the viral determinants. Early BKV positivity of urine and blood indicates later BKV nephropathy. Decreased renal function may favor BKV infection.

Prevalence and Distribution of BK virus Subtypes in Renal Transplant Recipients Referred to Golestan Hospital in Ahvaz, Iran

BACKGROUND

BK virus (BKV) belongs to the human Polyomaviridae and the primary BKV infection is occurred during childhood then the virus could be latent through life, especially in the kidneys and urinary system. It became reactive after an immunocompromised status, such as pregnancy or transplantation. Isolated BKV from different locations of the world is grouped into four subtypes using serological and genotyping methods. The BKV subtype I is the dominant one and has worldwide distribution.

OBJECTIVES

According to our knowledge, there are no data about the BKV prevalence and its genotypes in southwest part of Iran. Considering the high prevalence of renal failure and kidney transplant patients in this part, and the role of BKV in graft rejection, this study aimed to determine the prevalence of BKV infection in renal transplant recipients referred to Golestan Hospital in Ahvaz City, Iran.

PATIENTS AND METHODS

Urine samples were collected from 122 kidney transplant recipients referred to Golestan Hospital in Ahvaz, southwest of Iran. The extracted DNA was amplified by Polymerase Chain Reaction, and subtype of each positive sample was determined using Restriction Fragment Length Polymorphism (RFLP) and sequencing methods.

RESULTS

From all study population, 51/122 (41.8%) urine samples were positive for BKV DNA and the other samples were negative (71/122). Forty-eight cases (94.11%) were subtype I and 3 others (5.89%) were subtype IV using the RFLP method. None of the patient's urine samples were positive for subtypes II and III.

CONCLUSIONS

Our work is the second study in Iran and considering huge numbers of transplantation in Iran and Khuzestan Province, south western of Iran, in addition to the role of this virus in kidney transplant rejection, routine evaluation of BKV positivity is recommended both for graft recipient and donors. This helps better transplantation result and may prevent graft rejection.

Molecular characterization of BK and JC viruses circulating among potential kidney donors in Kuwait

BK and JC polyomaviruses can be associated with nephropathy following renal transplantation. The aim of this study was to determine the prevalence, load, and genotypes of BK and JC viruses circulated in potential kidney donors in Kuwait. The detection of polyomavirus DNA was carried out in serum and urine samples of 165 potential kidney donors. Seventy (42%) individuals were tested positive for polyomavirus DNA, of whom 20 (12%) had detectable polyomavirus DNA in their serum samples, 40 (24%) in their urine samples, and 10 (6%) in both serum and urine samples. In the group of polyomavirus-positive patients, JC DNA could be detected in 78% of urine samples and 11% of serum samples, whereas BK DNA could be detected in 7% of urine samples and 3% of serum samples. The median polyomaviral load was low. The detected BK sequences in Kuwaiti adults formed new clusters sharing common ancestor with subgroups Ib1 and IVc, which are prevalent in Asia and Europe. Additionally, around half of the detected JCV sequences in Kuwaiti adults formed new clusters within the African subtype 3. Our results suggest high rate of polyomavirus shedding among healthy adults in Kuwait that can jeopardize their suitability for kidney donation.

Molecular characterization of BK polyomavirus subtypes in renal transplant recipients in Brazil

BK polyomavirus (BKV) is highly prevalent in the world population. Different reports indicate that BKV subtypes and subgroups present an uneven geographical distribution which might be correlated with human migration. However, there is a lack of data on the BKV subtype distribution in the South American population. The occurrence of BKV subtypes and subgroups detected in 51 kidney transplant recipients in Rio de Janeiro, Brazil is described. According to genetic studies, the population in this region descends mainly from European or African immigrants, with a relatively low genetic background from the Amerindians. By sequencing the VP1 region of BKV, subgroups Ib1 and Ia of subtype I were found in 34 (67%) and 15 (29%), respectively, of samples, while subtype II was present in 2 (4%) of the samples. Subtypes III and IV were not detected. Phylogenetic analysis indicated similarities between Brazilian BKV subgroup Ia and East African lineages; and subgroup Ib-1 with Asian and North American lineages, while subtype II samples were similar to sequences from Japan and the UK. This is the first report that describes distribution of BKV subtypes in South America. The high prevalence of BKV subgroup Ia probably reflects the high proportion of African descendants in this population. On the other hand, the predominance of subgroup Ib-1 and the absence of Ib-2 in an area with a high proportion of European ancestry was unexpected. Further studies in South American populations are needed to provide a better understanding of the epidemiology of BKV in this region.

Different patterns of BK and JC polyomavirus reactivation following renal transplantation

AIM

Reactivation of latent BK polyomavirus (BKV) infection is relatively common following renal transplantation and BKV-associated nephropathy has emerged as a significant complication. JC polyomavirus (JCV) reactivation is less well studied. The aim of the study was to determine reactivation patterns for these polyomaviruses in renal transplant recipients using an in-house quantitative real-time multiplex PCR assay and IgG serological assays using recombinant BK and JC virus-like particles.

METHODS

Retrospective analysis of urine and plasma samples collected from 30 renal transplant patients from February 2004 to May 2005 at Leeds Teaching Hospitals NHS Trust. Samples were collected at 5 days and thereafter at 1, 3, 6 and 12 months post-transplantation.

RESULTS

Eight patients (26.7%) were positive for BK viruria; three of these patients submitted plasma samples and two had BK viraemia. Five patients (16.7%) were positive for JC viruria. A corresponding rise in BKV and JCV antibody titres was seen in association with high levels of viruria.

CONCLUSIONS

Different patterns of reactivation were observed: BK viruria was detected after 3-6 months, and JC viruria was observed as early as 5 days post-transplantation. One patient had biopsy-proven BKV nephropathy. No dual infections were seen. In order to ensure better graft survival, early diagnosis of these polyomaviruses is desirable.

BK virus nephropathy and kidney transplantation

Nephropathy from BK virus (BKV) infection is an evolving challenge in kidney transplant recipients. It is the consequence of modern potent immunosuppression aimed at reducing acute rejection and improving allograft survival. Untreated BKV infections lead to kidney allograft dysfunction or loss. Decreased immunosuppression is the principle treatment but predisposes to acute and chronic rejection. Screening protocols for early detection and prevention of symptomatic BKV nephropathy have improved outcomes. Although no approved antiviral drug is available, leflunomide, cidofovir, quinolones, and intravenous Ig have been used. Retransplantation after BKV nephropathy has been successful.