Serum Antibodies Against the Oncogenic Merkel Cell Polyomavirus Detected by an Innovative Immunological Assay With Mimotopes in Healthy Subjects.

Merkel cell polyomavirus (MCPyV), a small DNA tumor virus, has been detected in Merkel cell carcinoma (MCC) and in normal tissues. Since MCPyV infection occurs in both MCC-affected patients and healthy subjects (HS), innovative immunoassays for detecting antibodies (abs) against MCPyV are required. Herein, sera from HS were analyzed with a novel indirect ELISA using two synthetic peptides mimicking MCPyV capsid protein epitopes of VP1 and VP2. Synthetic peptides were designed to recognize IgGs against MCPyV VP mimotopes using a computer-assisted approach. The assay was set up evaluating its performance in detecting IgGs anti-MCPyV on MCPyV-positive (n=65) and -negative (n=67) control sera. Then, the ELISA was extended to sera (n=548) from HS aged 18-65 yrs old. Age-specific MCPyV-seroprevalence was investigated. Performance evaluation indicated that the assay showed 80% sensitivity, 91% specificity and 83.9% accuracy, with positive and negative predictive values of 94.3% and 71%, respectively. The ratio expected/obtained data agreement was 86%, with a Cohen's kappa of 0.72. Receiver-operating characteristic (ROC) curves analysis indicated that the areas under the curves (AUCs) for the two peptides were 0.82 and 0.74, respectively. Intra-/inter-run variations were below 9%. The overall prevalence of serum IgGs anti-MCPyV in HS was 62.9% (345/548). Age-specific MCPyV-seroprevalence was 63.1% (82/130), 56.7% (68/120), 64.5% (91/141), and 66.2% (104/157) in HS aged 18-30, 31-40, 41-50 and 51-65 yrs old, respectively (p>0.05). Performance evaluation suggests that our indirect ELISA is reliable in detecting IgGs anti-MCPyV. Our immunological data indicate that MCPyV infection occurs asymptomatically, at a relatively high prevalence, in humans.

Clinical features of BK-polyomavirus and cytomegalovirus co-infection after kidney transplantation.

BK polyomavirus (BKPyV) and cytomegalovirus (CMV) are the main viral pathogens affecting the graft and recipient outcome after allogenic kidney transplantation. It has recently been found that infection with both viruses has a greater impact on kidney graft function than a single infection. We retrospectively analyzed a cohort of 723 recipients who received kidney transplantation between 2007 and 2015 after living and postmortal donation for differences in risk and outcome parameters regarding BKPyV (DNAemia) and CMV (CMV DNAemia) co-infection compared to sole viremias and to patients without viremia. Of all kidney allograft recipients in our cohort, 8.2% developed co-infection with BKPyV DNAemia and CMV DNAemia, 15.1% showed BKPyV viremia alone and 25.2% sole CMV DNAemia. Acute rejection was closely linked with co-infection (multivariable analysis, p = 0.001). Despite the fact that the estimated glomerular filtration rate of patients with co-infection was noticeably reduced compared to patients with BKV or CMV infection alone, transplant survival and patient survival were not significantly reduced. Co-infection with BKPyV and CMV in kidney transplanted patients is significantly associated with inferior allograft function. Since co-infection is strongly associated with acute rejection, co-infected individuals should be considered a risk collective.

Plasma Cell Pododermatitis Associated With Feline Leukemia Virus (FeLV) and Concomitant Feline Immunodeficiency Virus (FIV) Infection in a Cat.

This report aims to describe one case of plasma cell pododermatitis associated with feline leukemia virus (FeLV) and concomitant feline immunodeficiency virus (FIV) infection in a cat. A 2-year-old, intact male, mixed-breed cat was presented with alopecia, skin peeling, and erythematous swelling in the left metacarpal paw pad. Swelling, softening, ulceration with secondary crusts, and erythematous to violaceous discoloration were observed in multiple metacarpal, metatarsal, and digital paw pads. Complete blood count and serum biochemistry were analyzed. FeLV antigenemia and FIV seropositivity were assessed by immunoassay (enzyme-linked immunosorbent assay). Nested-PCR was used to detect FIV and FeLV proviral DNA in blood cells. Histopathological examination and anti-FeLV and anti-FIV immunohistochemical were performed on paw pad biopsies. According to clinical and histopathological findings, a diagnosis of plasma cell pododermatitis was made. The cat was FIV and FeLV seropositive. The immunohistochemical of paw pad biopsies revealed FeLV positivity and FIV negativity. This study provides reference for further investigations about feline plasma cell pododermatitis and highlights retrovirus infection as a potential factor associated with this disease.

Association of Pretransplant BK Polyomavirus Antibody Status with BK Polyomavirus Infection After Kidney Transplantation: A Prospective Cohort Pilot Study of 47 Transplant Recipients.

BACKGROUND: Prevention and early detection of BK polyomavirus (BKV) infection is important for long-term kidney graft survival; hence, pretransplant screening methods are essential to identify recipients at high risk for BKV infection. This study investigated the association of pretransplant donor and recipient BKV antibody status with the occurrence of post-transplant BKV infection. METHODS: We prospectively enrolled 47 adult living donor kidney transplant pairs from December 2014 to January 2016. Recipient and donor pretransplant BKV antibody titer was measured by hemagglutination inhibition (HI) test. Donor and recipient median HI titer of 1:20 was used as a cutoff to define seropositivity. Recipients were divided into 2 groups (BKV antibody donor-seropositive/recipient-seronegative (D+/R-) and non-D+/R-). Urinary cytology was used to screen for BKV infection. Plasma polymerase chain reaction testing for BKV DNA was used when decoy cells in urine were persistently detected. RESULTS: Nine (19.2%) of 47 patients belonged to the D+/R- group. Decoy cells were observed in 32 recipients (68.1%) during follow-up. BK viremia occurred in 3 (6.4%) cases. The maximum decoy cell count was significantly higher in the D+/R- group than in the non-D+/R- group (P = .0002). Decoy-cell-free survival was significantly shorter in the D+/R- group (P = .0220). Multivariate analysis identified only BKV antibody serostatus as an independent risk factor for decoy cell appearance (P = .0491). CONCLUSIONS: Pretransplant donor and recipient BKV antibody status was associated with higher maximum decoy cell count and shorter decoy-cell-free survival after kidney transplantation.

BK polyomavirus nephropathy with systemic viral spread: Whole genome sequencing data from a fatal case of BKPyV infection.

BK polyomavirus (BKPyV) infections with multi-organ involvement are rare. Here, we report for the first time whole genome sequencing data from a patient with systemic BKPyV disease. She presented post stem cell transplantation with graft-vs-host disease, suffered from profound immunosuppression, and developed fatal BKPyV disease of kidneys, lungs, and pancreas. The lytic infection was caused by an episomal BKPyV-Ib strain with canonical structural and receptor encoding gene sequences. However, DNA from all infected tissue sites showed diverse BKPyV-NCCR rearrangements (rr-NCCR) involving the P, Q, and R domains, while largely sparing O and S, carrying initiation sites for early and late BKPyV gene transcripts crucial for viral replication and assembly. Common to all rr-NCCR variants was a break point in Q (position 17-27) that can form the nidus for double DNA strand break formation and gene rearrangements. Metastatic clonal BKPyV spread from kidneys to other organs was not detected. We hypothesize that lack of immune surveillance and a specific NCCR break point promote profound gene rearrangements of NCCR-P, Q, and R with alterations of regulatory feedback loops. As a result, viral replication and pathogenicity are enhanced leading to severe, often fatal systemic disease not caused by the common archetypical BKPyV strains.

Investigation of the Relationship Between BK Virus and Human Leukocyte Antigens in Kidney Transplant Recipients.

OBJECTIVES: The main function of HLA is to present antigens to lymphocytes and to initiate specific immune responses. Autoimmune, viral, allergic, and neurologic diseases have been found to be related to HLA molecules. In renal transplant, the main target of the recipient's immune system is the HLA molecules on the surface of donor cells. HLA also plays a role in the development of an immune response to viral infections. After renal transplant, BK virus infections may occur due to immunosuppression. Here, we investigated the relationship between HLA and BK virus in renal transplant recipients. MATERIALS AND METHODS: This retrospective study investigated HLA-A, HLA-B, and HLA-DR tissue typing before renal transplant. DNA was isolated from whole blood, and tissue typing tests were performed based on polymerase chain reaction. Patients were tested for BK virus posttransplant using DNA isolated from urine and/or plasma samples. RESULTS: We found HLA-B*13 allele to be a protective factor (P < .049; odds ratio: 0.131; 95% confidence interval, 0.017-1.029) and HLA-DRB1*03 allele to be a possible risk factor (P < .029; odds ratio: 2.521; 95% confidence interval, 1.157-5.490) against BK virus. No significant relationships were found between BK virus and age, sex, donor type, and HLA mismatch. CONCLUSIONS: HLA class I molecules are known to be effective against viruses with the help of cytotoxic T cells. HLA-B*13 alleles within the HLA class I molecules were identified as protective factors against BK virus. HLA class II is associated with CD4-positive T cells that help secrete immune system cytokines, playing a role in stimulating and suppressing the immune system. We demonstrated that HLA-DRB1*03 allele could be a risk factor against BK virus. This allele may be associated with immunomodulatory cytokine secretion of the immune system.

Screening for BKV-DNAEMIA after renal transplantation in a resource limited setting.

Costs may hinder the implementation of BK polyomavirus (BKV)-DNAemia screening in resource-limited kidney transplant (KT) centers. We analyzed data from two studies to assess the performance and potential cost saving of a dual-step screening strategy based on the use of a preliminary qualitative semi-nested PCR (snPCR) assay followed by BKV-DNAemia quantification after KT. In the preliminary study, in which 130 samples from 33 KT recipients were screened for BKV-DNAemia, the estimated positive and negative predictive values of snPCR, as compared to quantitative PCR (qPCR), were 88% and 99%, respectively. In the second study, which included 84 KT recipients, BKV-DNAemia was detected by snPCR in 28/472 (5.9%) samples and confirmed by qPCR in 26 samples of 21 (25%) subjects. No graft loss occurred among KT recipients who developed BKV-DNAemia. Cost analyses suggested that this strategy might be a cost saving alternative for BKV-DNAemia screening for some resource-limited settings.

Monitoring of the shedding and serological dynamics of Bovine gammaherpesvirus type 4 in a dairy cattle herd.

Bovine gammaherpesvirus type 4 (BoHV-4) is increasingly related with reproductive disease in cattle, but its epidemiology is not fully understood. We monitored the serological response and shedding of BoHV-4 in a positive dairy cattle farm with metritis. First, we performed an ELISA to detect BoHV-4 antibodies in all the animals (n = 104). Afterwards, ten seronegative heifers introduced in the production lot and sera samples were monthly taken for four months and then 6-10 months after introduction to detect BoHV-4 antibodies by ELISA. Moreover, a vaginal swab was taken after calving to detect BoHV-4 by PCR. Concurrently, a weekly collection of vaginal and nasal swabs and milk was performed during the first month post-partum in multiparous cows with metritis (n = 14), heifers with metritis (n = 4), heifers without metritis but positive to BoHV-4 (ELISA or PCR) (n = 2) and multiparous cows without metritis (n = 3). Seropositivity was higher in older animals and in the production lot. Three heifers which shed BoHV-4 after parturition resulted seronegative at first but eventually seroconverted. In the same vein, most heifers seroconverted after 6-10 months in the production lot (8/10). Multiparous cows shed virus by various routes: 13/14 (93 %) in vaginal secretions, 7/14 (50 %) in nasal exudates and 7/14 (50 %) in milk. However, in the other groups, shedding was only detected in vaginal swabs from the first week post-partum. Our study describes BoHV-4 shedding in field conditions. Seronegative animals may become horizontally infected when moved to a contaminated environment.

Measurement of BK-polyomavirus Non-Coding Control Region Driven Transcriptional Activity Via Flow Cytometry.

Polyomaviruses, like the BK-polyomavirus (BKPyV), can cause severe pathologies in immunocompromised patients. However, since highly effective antivirals are currently not available, methods measuring the impact of potential antiviral agents are required. Here, a dual fluorescence reporter that allows the analysis of the BKPyV non-coding control-region (NCCR) driven early and late promoter activity was constructed to quantify the impact of potential antiviral drugs on viral gene expression via tdTomato and eGFP expression. In addition, by cloning BKPyV-NCCR amplicons which in this protocol have been exemplarily obtained from the blood-derived DNA of immunocompromised renal transplanted patients, the impact of NCCR-rearrangements on viral gene expression can be determined. Following cloning of the patient derived amplicons, HEK293T cells were transfected with the reporter-plasmids, and treated with potential antiviral agents. Subsequently, cells were subjected to FACS-analysis for measuring mean fluorescence intensities 72 h post transfection. To also test the analysis of drugs that have a potential cell cycle inhibiting effect, only transfected and thus fluorescent cells are used. Since this assay is performed in large T Antigen expressing cells, the impact of early and late expression can be analyzed in a mutually independent manner.

Predictive Value of the Combination of Peripheral Blood Lymphocyte Count and Urinary Cytology in BK Polyomavirus-associated Nephropathy.

BACKGROUND: Graft biopsy is the gold standard for diagnosis of BK polyomavirus-associated nephropathy (BKPyVAN), and polymerase chain reaction is the most specific screening technique. Development of a noninvasive, cost-effective marker for BKPyVAN is important. METHODS: We reviewed 492 adult kidney transplant patients. We investigated peripheral blood lymphocyte (PBL) count and urinary cytology at graft biopsy in patients with BKVPyAN (n = 21), acute T-cell-mediated rejection (n = 79), and no evidence of acute rejection (n = 149). We performed univariate and multivariate logistic regression and receiver operating characteristics analyses to compare the test performance of PBL count, urinary cytology, and their combination for diagnosis of BKPyVAN. RESULTS: The PBL count at biopsy was significantly lower in the BKPyVAN group than the acute T-cell-mediated rejection and no acute rejection groups (959 ± 290/µL, 1433 ± 673/µL, and 1531 ± 549/µL, respectively; P < .01). The PBL count was 959 ± 290/µL at diagnosis of BKPyVAN and increased to 1123 ± 377/µL, 1238 ± 419/µL, and 1292 ± 491/µL at 1, 2, and 3 months after treatment, respectively (P < .05). On univariate analysis, the area under the curve was significantly higher for the combined model than for PBL and cytology alone (0.930, 0.797, and 0.875, respectively; P < .01). The improved test performance in the combined model remained significant after multivariate adjustment (0.972, 0.844, and 0.928, respectively; P < .01). CONCLUSIONS: Decreased PBL count was found in BKPyVAN, and the predictive performance of the combination of PBL count and urinary cytology was significantly enhanced for diagnosis of BKPyVAN.

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.

The frequency of Merkel cell polyomavirus in whole blood from immunocompetent and immunosuppressed patients with kidney disease and healthy donors.

Merkel cell polyomavirus (MCPyV) is a rare, aggressive and related to human diseases in immunocompromised patients. MCPyV has been detected in skin neoplasms, various cancers, immunosuppressed patients and immunocompetent individuals. Several studies have confirmed the presence of MCPyV in patients with kidney dysfunction, such as kidney transplant (KTx) and long-term dialysis patients. The aims of this study were to quantify and compare the frequency of MCPyV in whole blood samples from immunocompetent and immunosuppressed patients and healthy blood donors and to compare MCPyV genotypes in a Korean population. DNA from Groups 1, 2, and 3 was screened for MCPyV using polymerase chain reaction (PCR) and quantitative real-time PCR (qPCR) with primer pairs targeting two regions of the large T-antigen. Thirteen of 122 whole-blood samples (12.7%) were positive for MCPyV. The virus was detected in the three groups of patients and healthy donors; specifically, in 5 of 30 (16.7%) KTx patients (Group 1), 6 of 52 (11.5%) dialysis patients (Group 2), and 4 of 40 (10%) healthy donors (Group 3). Low viral DNA loads 4.4-18 copies/µl were observed using qPCR DNA sequences from the two MCPyV-LT regions, which showed high homology with MCPyV sequences belonging to the TKS strain from Japan rather than the Chinese/European/North American strains. The MCPyV DNA was similarly amplified in whole blood from immunocompetent and immunosuppressed patients and healthy donors. This virus may be involved in establishing the persistence of infected peripheral leukocytes in the host, based on the incidence of detection of MCPyV DNA in blood samples from immunocompromised and immunocompetent subjects. This study is the first to identify a Korean MCPyV strain in whole-blood samples from Korean patients with kidney disease and healthy individuals.

Polyomaviruses BK and JC DNA infection in peripheral blood cells from blood donors.

OBJECTIVES: To investigate the prevalence of human polyomavirus (BK and JC viruses) infection in peripheral blood mononuclear cells of healthy blood donors. METHODS: The study included 250 healthy blood donors. Five-milliliter blood was drawn into sterile EDTA tubes and PBMCs were isolated from whole blood. The isolated PBMCs were counted and stored at -70°C for future investigation. DNA was extracted and subjected to simple, sensitive and specific semi-nested PCR as well as QPCR using both general and specific primers for different assays. RESULTS: Of 250 blood samples, 66 (26.4%) were positive for BKV DNA (146-34,514 copies/106 cells). JC DNA was found in 45 (18%) blood samples (65-21,250 copies/106 cells). Co-infection with these viruses were found in 11 (4.4%) out of 250 blood samples. DISCUSSION: Our study provides important data on polyomavirus infection in peripheral blood mononuclear leukocytes in immunocompetent individuals. These data indicate significant differences between the prevalence of BKV and JCV infection in healthy blood donors. The prevalence of BK and JC virus infection is higher in the age range 30-39 years compared to other age ranges.

Polyomaviruses BK and JC DNA infection in peripheral blood cells from blood donors

ABSTRACT Objectives: To investigate the prevalence of human polyomavirus (BK and JC viruses) infection in peripheral blood mononuclear cells of healthy blood donors. Methods: The study included 250 healthy blood donors. Five-milliliter blood was drawn into sterile EDTA tubes and PBMCs were isolated from whole blood. The isolated PBMCs were counted and stored at −70 °C for future investigation. DNA was extracted and subjected to simple, sensitive and specific semi-nested PCR as well as QPCR using both general and specific primers for different assays. Results: Of 250 blood samples, 66 (26.4%) were positive for BKV DNA (146-34,514 copies/106 cells). JC DNA was found in 45 (18%) blood samples (65-21,250 copies/106 cells). Co-infection with these viruses were found in 11 (4.4%) out of 250 blood samples. Discussion: Our study provides important data on polyomavirus infection in peripheral blood mononuclear leukocytes in immunocompetent individuals. These data indicate significant differences between the prevalence of BKV and JCV infection in healthy blood donors. The prevalence of BK and JC virus infection is higher in the age range 30-39 years compared to other age ranges.

Cross-sectional associations between cutaneous viral infections and regulatory T lymphocytes in circulation.

BACKGROUND: Cutaneous viral infections and immune suppression are risk factors for some forms of nonmelanoma skin cancer; however, their interrelationship is poorly understood. OBJECTIVES: To examine cross-sectional associations between cutaneous viral infections and circulating forkhead-box P3 (FOXP3)-expressing T-regulatory (Treg) cells, suppressive cells that dampen effective antitumour immunity. MATERIALS AND METHODS: Blood, eyebrow hair (EBH) and skin swab (SSW) samples were collected from 352 patients 60 years and older undergoing skin screening, without prevalent skin cancer, while participating in an ongoing prospective cohort study of cutaneous viral infections and skin cancer. DNA corresponding to 98 cutaneous human papillomavirus (HPV) types and five human polyomaviruses (HPyV) was assessed in EBH and SSW. Distinct classes of circulating Treg-cell subpopulations were defined by flow cytometry including cutaneous lymphocyte antigen (CLA) and CCR4high Treg cells, both previously associated with cutaneous diseases. Age- and sex-adjusted associations between circulating T-cell populations and infection were estimated using logistic regression. RESULTS: Total Treg-cell proportion in peripheral blood was not associated with ß HPV or HPyV infection. However, the proportion of circulating CLA+ Treg cells was inversely associated with γ HPV EBH infection [odds ratio (OR) 0·54, 95% confidence interval (CI) 0·35-0·84]. Interestingly, circulating Treg cells expressing markers indicative of antigen activation (CD27- CD45RA- FOXP3+ CD4+ ) were also inversely associated with γ HPV infection in SSW (OR 0·55, 95% CI 0·30-0·99) and EBH (OR 0·56, 95% CI 0·36-0·86). CONCLUSIONS: Inverse associations between circulating Treg cells and γ HPV infection suggest that localized viral infection may promote immunosuppressive cell migration into skin.

Clinical and Molecular Features of Feline Foamy Virus and Feline Leukemia Virus Co-Infection in Naturally-Infected Cats.

Feline foamy virus (FFV) and feline leukemia virus (FeLV) belong to the Retroviridae family. While disease has not been reported for FFV infection, FeLV infection can cause anemia and immunosuppression (progressive infection). Co-infection with FFV/FeLV allows evaluation of the pathogenic potential and epidemiology of FFV infection in cats with FeLV pathology. Blood and buccal swab samples from 81 cats were collected in Rio de Janeiro. Plasma was serologically tested for FeLV. DNA extracted from peripheral blood mononuclear cells and buccal swabs was used to PCR detect FFV and FeLV. A qPCR was developed to detect and measure FFV proviral loads (pVLs) in cats. FeLV qPCR was performed using previous methods. The median log10 pVL of FFV mono-infected individuals was lower than found in FFV/FeLV co-infected cats in buccal swabs (p = 0.003). We found 78% of cats had detectable buccal FFV DNA in FFV mono-infected and FFV co-infected FeLV-progressive cats, while in FeLV-regressive cats (those without signs of disease) 22% of cats had detectable buccal FFV DNA (p = 0.004). Our results suggest that regressive FeLV infection may reduce FFV saliva transmission, the main mode of FV transmission. We did not find evidence of differences in pathogenicity in FFV mono- and -dually infected cats. In summary, we show that FVs may interact with FeLV within the same host. Our study supports the utility of cats naturally co-infected with retroviruses as a model to investigate the impact of FV on immunocompromised mammalian hosts.

High prevalence of serum IgG antibodies reacting to specific mimotopes of BK polyomavirus, a human oncogenic polyomavirus, in patients affected by uveal melanoma.

The uveal melanoma (UM) is the most common human intraocular tumor. The BK polyomavirus (BKPyV) is a small DNA tumor virus whose footprints have been detected in different human cancers. BKPyV has oncogenic potential. Indeed, BKPyV, when inoculated into experimental animals, induces tumors of different histotypes, whereas in vitro, it transforms mammalian cells, including human cells from distinct tissues. In this investigation, the association between UM and BKPyV was studied employing indirect enzyme-linked immunosorbent assays (ELISAs) using synthetic peptides that mimic BKPyV viral capsid 1 (VP1) antigens. Indirect ELISAs were used to detect serum IgG antibodies against this polyomavirus with oncogenic potential in samples from patients with UM and controls, represented by healthy subjects (HS). It was found that serum samples from patients with UM had a higher prevalence of BKPyV antibodies, 85% (51/60), compared with that detected in HS1, 62% (54/87), and HS2, 57% (68/120). The different prevalence of BKPyV antibodies detected in UM versus the two control groups, HS1 and HS2, is statistically significant (p < 0.005). Our immunologic data suggest a significantly higher prevalence of antibodies against BKPyV VP1 epitopes in serum samples from patients with UM compared with HS. These results indicate an association between UM and BKPyV, suggesting that this small DNA tumor virus may be a cofactor in the UM onset or progression.

Prediction of BK viremia by urine viral load in renal transplant patients: An analysis of BK viral load results in paired urine and plasma samples.

BK virus (BKPyV)-associated nephropathy (BKPyVAN) may affect up to 10% of renal transplant recipients, causing graft failure in the absence of intervention. The dilemma in monitoring BKPyVAN in renal transplant patients has been that only testing urine BK viral load represents higher sensitivity (earlier detection) but lower specificity, while testing plasma BK viral load represents lower sensitivity (later detection) but higher specificity. However, blindly testing both urine and plasma inevitably contributes to unnecessary medical cost. We analyzed 1030 paired urine and plasma BKPyV viral load results and identified a reliable urine BKPyV viral load cutoff (4.0 log IU/mL) that can predict BKPyV viremia with 99.7% negative predictive value (NPV). We propose a cost-effective screening algorithm to first only monitor the urine BKPyV levels until the viral load reaches 4.0 log IU/mL, and then only monitor plasma with higher frequency. This approach ensures 98.7% sensitivity of catching the earliest BKPyV viremia onset, and 100% sensitivity of detecting the critical BKPyV viremia. In addition, we identified a urine BKPyV viral load cutoff of 6.7 log IU/mL as predictive of critical BKPyV viremia (defined as plasma viral load >4.0 log IU/mL) with 100% sensitivity and 100% NPV.