BK and JC virus infections in recipients of bone marrow transplants

Incidence of hemorrhagic cystitis following unmanipulated peripheral blood stem cell transplantation in acute Leukemia: A retrospective single-center risk factor analysis

BACKGROUND

Hemorrhagic cystitis (HC) is an important adverse event experienced after hematopoietic stem cell transplantation (HSCT). Severe HC could lead to significant morbidity, prolonged hospitalization with increased health-care costs, and may cause considerable mortality.

OBJECTIVES

In order to investigate the influence of different contributing factors other than BK viruria on HC occurrence in a homogenous population, we retrospectively analyzed the potential risk factors.

STUDY DESIGN

We conducted a retrospective study among 200 patients (median age 12.4 years, IQR: 7.9-16.1) with acute leukemia who received peripheral blood allogenic HSCT after radiation-free myeloablative conditioning regimen, in pediatric cell therapy department of Research Institute for Oncology, Hematology and Cell Therapy (RIOHCT), Tehran, Iran, between December 2014 and December 2021. Associations between risk factors and outcomes were examined by univariable and multivariable logistic regression models.

RESULTS

A total of 46 patients (23%) had developed HC during the study period. The median onset of HC was 29 (IQR: 24-37) days post-transplant, and it persisted for a median of 33 (7-270) days. The incidence of HC in our patients was estimated to be 3 in 1000 cases (95% CI: 2-4). The results of multivariable logistic model shows that the chance of HC in T-cell acute lymphoblastic leukemia (ALL) compared to B-cell All is nearly five times more (OR = 4.88; 95%CI: (1.51-15.78), P = 0.008). The incidence of HC in patients who underwent HSCT from haploidentical donors was significantly higher than full matched donors (P < 0.001). Undergoing transplant from a matched unrelated and haploidentical donor both augment the chance of HC in about six times more than matched related donors (OR = 6.36; 95%CI: (1.58-25.49), P = 0.009 and OR = 5.7; 95%CI: (1.83-17.75), P = 0.003, respectively). In patients who developed HC compared to non-HC group, overall survival was much worse (P < 0.001).

DISCUSSION

Most studies have failed to demonstrate any relationship between late-onset HC and the dose of cyclophosphamide. In our study, although the dose of cyclophosphamide was similar in HSCT from MRD and MUD, the hazard of HC incidence was significantly higher in the latter group. This could be accredited to ATG, as in patients in the MRD group who had not received any ATG, the incidence of HC was much lower than the patients who had underwent HSCT from MUD or haploidentical donor group.

CONCLUSIONS

Patients with T-cell ALL and those who under haploidentical HSCT had the highest incidence of HC.

Prospective Analysis of Hemorrhagic Cystitis and BK Viremia in Allogeneic Hematopoietic Stem Cell Transplantation

Objective

BK virus (BKV) infection has been shown to be related to hemorrhagic cystitis (HC) in allogeneic hematopoietic stem cell transplantation (allo-HSCT). There are conflicting data regarding the association between BKV titers in plasma and clinical disease as well as the risk factors for BKV-related HC. Our aim is to study the risk factors and relationship with plasma BK viral load for development of HC in a prospective analysis.

Materials and Methods

We prospectively evaluated 59 patients who received allo-HSCT between 2014 and 2016 by quantitative BK virus polymerase chain reaction (PCR) (Altona Diagnostics, Germany) from blood samples at days 0, 30, 60, and 90 after allo-HSCT. The patients were monitored for signs and symptoms of HC.

Results

HC was diagnosed in 22 patients (37%) at a mean of 100 days (range: 0-367 days). In multivariate analysis, the usage of cyclophosphamide (sub-distribution hazard ratio [sdHR]: 7.82, confidence interval [CI]: 1.375-39.645, p=0.02), reactivated CMV (sdHR: 6.105, CI: 1.614-23.094, p=0.008), and positive BKV viremia (sdHR: 2.15, CI: 1.456-22.065, p=0.01) significantly increased the risk of developing HC. Patients with higher viral loads at day 30 and day 60 were diagnosed with more severe HC (p<0.001). Median BK viral loads of >101.5 copies/mL at day 0 (sensitivity 0.727, specificity 0.875), >98.5 copies/mL at day 30 (sensitivity 0.909, specificity 0.875), and >90.0 copies/mL at day 60 (sensitivity 0.909, specificity 0.875) were indicative of HC.

Conclusion

Our study showed that administration of cyclophosphamide, CMV reactivation, and BK virus positivity were associated with HC. Plasma BK virus PCR titers at days 0, 30, and 60 after transplant were sensitive tools for predicting clinically proven HC.

Viral opportunistic infections in Mauritian cynomolgus macaques undergoing allogeneic stem cell transplantation mirror human transplant infectious disease complications

Allogeneic hematopoietic stem cell transplantation (HSCT) and xenotransplantation are accompanied by viral reactivations and virus-associated complications resulting from immune deficiency. Here, in a Mauritian cynomolgus macaque model of fully MHC-matched allogeneic HSCT, we report reactivations of cynomolgus polyomavirus, lymphocryptovirus, and cytomegalovirus, macaque viruses analogous to HSCT-associated human counterparts BK virus, Epstein-Barr virus, and human cytomegalovirus. Viral replication in recipient macaques resulted in characteristic disease manifestations observed in HSCT patients, such as polyomavirus-associated hemorrhagic cystitis and tubulointerstitial nephritis or lymphocryptovirus-associated post-transplant lymphoproliferative disorder. However, in most cases, the reconstituted immune system, alone or in combination with short-term pharmacological intervention, exerted control over viral replication, suggesting engraftment of functional donor-derived immunity. Indeed, the donor-derived reconstituted immune systems of two long-term engrafted HSCT recipient macaques responded to live attenuated yellow fever 17D vaccine (YFV 17D) indistinguishably from untransplanted controls, mounting 17D-targeted neutralizing antibody responses and clearing YFV 17D within 14 days. Together, these data demonstrate that this macaque model of allogeneic HSCT recapitulates clinical situations of opportunistic viral infections in transplant patients and provides a pre-clinical model to test novel prophylactic and therapeutic modalities.

BK virus infection in allogeneic hematopoietic cell transplantation: An update on pathogenesis, immune responses, diagnosis and treatments

In hematopoietic cell transplantation (HCT) patients, BK polyomavirus (BKPyV) infection results in significant morbidity mainly due to hemorrhagic cystitis (HC). Despite increased knowledge acquired over recent decades, no treatment has shown effectiveness in the management of organ damage in HCT allografts. This review summarizes the current knowledge on BKPyV, from the virus constitution to the pathophysiology and immune-related mechanisms. We next focus on BKPyV-induced HC in HCT to discuss the benefit of monitoring BKPyV viruria and viremia in the management of patients. At last, we review currently used therapeutics, along with future promising therapies to propose clinical and practical guidelines and further interesting research areas.

Impact of extended infusional mesna prophylaxis on the incidence of BK viruria and hemorrhagic cystitis following post-transplantation cyclophosphamide and CTLA4Ig-based haploidentical transplantation

Hemorrhagic cystitis (HC) has been reported with increased frequency following post-transplantation cyclophosphamide (PTCy)-based haploidentical hematopoietic cell transplantation (HCT) along with a strong association with BK viruria. We prospectively evaluated the incidence of BK viruria and HC in 115 patients (median age 20 years, 2-65) undergoing PTCy-based haploidentical HCT with (n = 71) or without (n = 44) CTLA4Ig. HC prophylaxis consisted of a continuous infusion of mesna 30 min prior and 48 h post-PTCy. The overall incidence of BK viruria was 65.7%. None with BK viruria < 10⁴ copies/ml developed clinical symptoms (n = 65). The incidence of BK viruria ≥ 10⁴ copies/ml was 7.1% (n = 8) and 75% developed HC. The incidence of HC was 5.4% at a median of 30 days. Both BK viruria ≥ 10⁴ copies/ml and HC were strongly associated with acute GVHD (p < 0.001). A higher NRM was observed in those with BK viruria ≥ 10⁴ copies/ml, related to GVHD and its complications (41.7% vs 12.6%, p = 0.04). The incidences of acute GVHD, vis-à-vis, overall BK viruria, BK viruria ≥ 10⁴ copies/ml, and HC, tended to be lower in patients receiving CTLA4Ig. Thus, extended infusional mesna, coupled with significant reduction in alloreactivity along with possible preservation of antiviral immunity associated with the use of CTLA4Ig, was probably responsible for a much lower incidence of BK viruria and resultant HC than reported previously following PTCy-based haploidentical HCT.

Reactivation of BK virus after double umbilical cord blood transplantation in adults correlates with impaired reconstitution of CD4+ and CD8+ T effector memory cells and increase of T regulatory cells

BK virus (BKV), a human polyomavirus that remains latent in renal epithelial cells, can be reactivated after hematopoietic stem cell transplantation (HSCT) leading to hemorrhagic cystitis. The incidence of BK viremia is higher after Umbilical cord blood transplantation (UCBT) than HSCT from adult donors. Data regarding the role of immune recovery after UCBT in BKV reactivation is lacking. We examined the correlation between the development of BK viremia and immune reconstitution in 27 adult recipients of UCBT. The incidence of BK viremia was 52% and developed most frequently within the first 8 weeks after the transplantation, but persisted in seven patients at 6 months, and three patients at 1-year post UCBT. Detection of BK viremia 1 year after transplant was negatively associated with the number of CD8⁺ cells (p = 0.03) and CD8⁺CD45RO⁺ cells (p = 0.05) at 6 months, and the number of CD4⁺ (p = 0.03) and CD4⁺CD45RO⁺ cells (p = 0.03) at 12 months after UCBT. Conversely, BK viremia at 6 and 12 months was positively correlated with the number of T regulatory (Treg) cells at 1 month (p = 0.005 and p = 0.016, respectively). Because UCB Treg have highly potent immunosuppressive function, our findings indicate that sustained BK viremia in UCBT recipients might be associated with the increase of Treg cells early after transplantation, which mediate impaired and delayed reconstitution of CD4⁺ and CD8⁺ T effector cells.

Increased risk of 100-day and 1-year infection-related mortality and complications in haploidentical stem cell transplantation

Background: While haploidentical transplantation has led to the near-universal availability of donors, several challenges for this form of transplant still exist. This study sought to investigate the rates of infection-related mortality and other complications following haploidentical vs nonhaploidentical transplant. Methods: We conducted a retrospective cohort study in adults with various malignant and benign hematological conditions who underwent allogeneic hematopoietic stem cell transplantation from 2011 to 2018. One hundred-day and 1-year overall survival were defined as survival from the time of transplant until 100 days or 1 year later. Results: A total of 187 patients were included in this study, with 45 (24.1%) receiving transplants from haploidentical donors and 142 (75.9%) from nonhaploidentical donors. There were similar rates of acute graft-versus-host disease (GVHD) (40% vs 38% in haploidentical vs nonhaploidentical recipients, P=0.86) and chronic GVHD (44.4% vs 43.7%, P=1). Rates of 100-day and 1-year infection-related mortality were significantly higher in the haploidentical group compared to the nonhaploidentical group (8.9% vs 1.4% at 100 days, P=0.03, and 15.9% vs 3.8% at 1 year, P=0.01). There were also higher rates of cytomegalovirus infections (59.1% vs 23.8%, P<0.01), BK virus-associated hemorrhagic cystitis (40.9% vs 8.4%, P<0.01), and BK viremia (15.9% vs 0.8%, P<0.01) in haploidentical recipients. Conclusions: Despite the use of identical antimicrobial prophylactic and treatment agents, haploidentical recipients were found to have significantly increased rates of 100-day and 1-year infection-related mortality as well as several other infectious complications.

Microbiome: An Emerging New Frontier in Graft-Versus-Host Disease

Hematopoietic cell transplantation is an intensive therapy used to treat high-risk hematological malignant disorders and other life-threatening hematological and genetic diseases. Graft-versus-host disease (GVHD) presents a barrier to its wider application. A conditioning regimen and medications given to patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HCT) are capable of disturbing the homeostatic crosstalk between the microbiome and the host immune system and of leading to dysbiosis. Intestinal inflammation in the context of GVHD is associated with loss in microbial diversity that could serve as an independent predictor of mortality. Successful gastrointestinal decontamination using high doses of non-absorbable antibiotics likely affect allo-HCT outcomes leading to significantly less acute GVHD (aGVHD). Butyrate-producing Clostridia directly result in the increased presence of regulatory T cells in the gut, which are protective in GVHD development. Beyond the microbiome, Candida, a member of the mycobiome, colonization in the gut has been considered as a risk factor in pathophysiology of aGVHD and reduction in GVHD is observed with antifungal prophylaxis with fluconazole. Reduced number of goblet cells and Paneth cells have been shown to associate with GVHD and has a significant impact on the micro- and mycobiome density and their composition. Lower levels of 3-indoxyl sulfate at initial stages after allo-HCT are related with worse GVHD outcomes and increased mortality. Increased understanding of the vital role of the gut microbiome in GVHD can give directions to move the field towards the development of improved innovative approaches for preventing or treating GVHD following allo-HCT.

Evaluation of infectious complications after haploidentical hematopoietic stem cell transplantation with post-transplant cyclophosphamide following reduced-intensity and myeloablative conditioning: a study on behalf of the Francophone Society of Stem Cell Transplantation and Cellular Therapy (SFGM-TC)

Several approaches have been developed to overcome historical barriers associated with poor outcomes in the setting of HLA-haploidentical allogeneic transplantation (HaploSCT). Here, we examine the outcome of patients with various hematological disorders undergoing HaploSCT with high-dose, post-transplantation cyclophosphamide. We performed a retrospective study on 381 patients from 30 centers between January 2013 and December 2015. At the last follow-up, a total of 1058 infectious episodes were diagnosed, affecting 90.3% of the cohort. Median time to first infection was 13 days for bacterial, 32 days for viral and 20 days for fungal infections. Around 41% of these infections were of bacterial origin and 35% of viral origin, among which 48.8% of patients presented CMV reactivation. Median of GVHD relapse-free survival, progression-free survival and overall survival were 7.1 months, 19.9 months and 33.5 months, respectively. HSCT procedure was the primary or contributing cause of death (55.6%), followed by relapse of the original disease (34.2%). Infections accounted for 45.7% of the HSCT-related deaths. The present multicenter data on a large cohort of patients receiving HaploSCT with PTCy confirmed the feasibility of the procedure with an acceptable incidence of infectious complications, not different as compared to other haploidentical platforms or HLA-matched transplantation.

Characterization of Jc Virus Dna Amplified from Urine of Chronic Progressive Multiple Sclerosis Patients

Thirty-seven chronic progressive multiple sclerosis (MS) patients, 20 of whom were taking cyclosporine, were examined for excretion of JC virus (JCV) in the urine. Polymerase chain reaction (PCR) amplification of DNA in urinary cell extracts detected JCV in 30% of the MS urines. In the cyclosporine treated group four of 20 (20%) excreted JCV, whereas in the untreated group seven of 17 (41%) excreted JCV. Thus, cyclosporine treatment did not enhance urinary excretion of the virus. A control group consisting of an unselected series of 89 patients donating urine in a general medical clinic and 16 healthy volunteers showed 41% with detectable urinary JCV. Thirty-three percent of the control females excreted JCV (18154), as did 49% of the control males (25151). Although the percentage of MS patients excreting detectable virus was not increased compared to the control group, the presence of JCV in the urine provides or convenient source of the virus for further characterization. Genotyping of DNA fragments amplified from the VPI region indicates mainly the presence of JCV Type 1 in these chronic progressive MS patients. This is also the type that predominates in the control group. An apparent recombinant between Type 1 and Type 3 (African) within the VPI region, tentatively designated Type 113 (or Type 4), was found in both the MS group and the controls. A larger series of MS patients that includes relapsing/remitting disease will be required to determine whether the genotype profile of JCV excreted in the urine of MS patients differs significantly from controls.

Progressive multifocal leukoencephalopathy in patients receiving rituximab and cyclophosphamide after haplo-identical T-cell replete transplantation and review of the literature

John Cunningham virus (JCV) reactivation, occurring mainly in immunocompromised patients, leads to progressive multifocal leukoencephalopathy, an uncommon but lethal disease. JCV reactivation after T-cell replete haploidentical stem cell transplantation, in the pre-cyclophosphamide era, is poorly represented in the literature. We therefore describe two cases of acute myeloid leukemia who developed JCV reactivation after receiving cyclophosphamide and rituximab post haploidentical stem cell transplantation, and review the literature, aiming to a better understanding of the disease course and its risk factors.

BK nephropathy in the native kidneys of patients with organ transplants: Clinical spectrum of BK infection

Nephropathy secondary to BK virus, a member of the Papoviridae family of viruses, has been recognized for some time as an important cause of allograft dysfunction in renal transplant recipients. In recent times, BK nephropathy (BKN) of the native kidneys has being increasingly recognized as a cause of chronic kidney disease in patients with solid organ transplants, bone marrow transplants and in patients with other clinical entities associated with immunosuppression. In such patients renal dysfunction is often attributed to other factors including nephrotoxicity of medications used to prevent rejection of the transplanted organs. Renal biopsy is required for the diagnosis of BKN. Quantitation of the BK viral load in blood and urine are surrogate diagnostic methods. The treatment of BKN is based on reduction of the immunosuppressive medications. Several compounds have shown antiviral activity, but have not consistently shown to have beneficial effects in BKN. In addition to BKN, BK viral infection can cause severe urinary bladder cystitis, ureteritis and urinary tract obstruction as well as manifestations in other organ systems including the central nervous system, the respiratory system, the gastrointestinal system and the hematopoietic system. BK viral infection has also been implicated in tumorigenesis. The spectrum of clinical manifestations from BK infection and infection from other members of the Papoviridae family is widening. Prevention and treatment of BK infection and infections from other Papovaviruses are subjects of intense research.

Polyomaviruses BK, JC, KI, WU, MC, and TS in children with allogeneic hematopoietic stem cell transplantation

Timely and reliable detection of viruses is of key importance in early diagnosis of infection(s) following allogeneic HSCT. Among the immunocompetent, infections with BKPyV and JCPyV are mostly subclinical, while post-HSCT, the former may cause HC and the latter PML. The epidemiology and clinical impact of the newly identified KIPyV, WUPyV, MCPyV, and TSPyV in this context remain to be defined. To assess the incidence and clinical impact of BKPyV, JCPyV, KIPyV, WUPyV, MCPyV, and TSPyV infections, we performed longitudinal molecular surveillance for DNAemias of these HPyVs among 53 pediatric HSCT recipients. Surveillance pre-HSCT and for three months post-HSCT revealed BKPyV DNAemia in 20 (38%) patients. Our data demonstrate frequent BKPyV DNAemia among pediatric patients with HSCT and the confinement of clinical symptoms to high copy numbers alone. MCPyV and JCPyV viremias occurred at low and TSPyV viremia at very low prevalences. KIPyV or WUPyV viremias were not demonstrable in this group of immunocompromised patients.

Activating receptor NKG2D targets RAE-1-expressing allogeneic neural precursor cells in a viral model of multiple sclerosis

Transplantation of major histocompatibility complex-mismatched mouse neural precursor cells (NPCs) into mice persistently infected with the neurotropic JHM strain of mouse hepatitis virus (JHMV) results in rapid rejection that is mediated, in part, by T cells. However, the contribution of the innate immune response to allograft rejection in a model of viral-induced neurological disease has not been well defined. Herein, we demonstrate that the natural killer (NK) cell-expressing-activating receptor NKG2D participates in transplanted allogeneic NPC rejection in mice persistently infected with JHMV. Cultured NPCs derived from C57BL/6 (H-2(b) ) mice express the NKG2D ligand retinoic acid early precursor transcript (RAE)-1 but expression was dramatically reduced upon differentiation into either glia or neurons. RAE-1(+) NPCs were susceptible to NK cell-mediated killing whereas RAE-1(-) cells were resistant to lysis. Transplantation of C57BL/6-derived NPCs into JHMV-infected BALB/c (H-2(d) ) mice resulted in infiltration of NKG2D(+) CD49b(+) NK cells and treatment with blocking antibody specific for NKG2D increased survival of allogeneic NPCs. Furthermore, transplantation of differentiated RAE-1(-) allogeneic NPCs into JHMV-infected BALB/c mice resulted in enhanced survival, highlighting a role for the NKG2D/RAE-1 signaling axis in allograft rejection. We also demonstrate that transplantation of allogeneic NPCs into JHMV-infected mice resulted in infection of the transplanted cells suggesting that these cells may be targets for infection. Viral infection of cultured cells increased RAE-1 expression, resulting in enhanced NK cell-mediated killing through NKG2D recognition. Collectively, these results show that in a viral-induced demyelination model, NK cells contribute to rejection of allogeneic NPCs through an NKG2D signaling pathway.

BK Virus and Its Role in Hematopoietic Stem Cell Transplantation: Evolution of a Pathogen

We reviewed the literature regarding disease induced by BK virus (BKV) in the hematopoietic stem cell transplant (HSCT) population, particularly hemorrhagic cystitis (HC) and nephritis. The association between BKV and HC has been reported over the past four decades. BKV has been clinically implicated and widely accepted as an etiologic agent of HC and nephritis in HSCT and nephropathy in renal transplant patients. We discuss the potential benefit of early initiation of therapy in patients who fail supportive care alone as well as the different treatment strategies for HC induced by BKV. Treatments that have been used such as cidofovir and leflunomide are accompanied by risks, and the benefits are not as concrete as with other viral illness in the HSCT population.

Antivirals for the treatment of polyomavirus BK replication

Antiviral drugs with specific activity against polyomavirus replication have not been developed in the past. This deficiency has become fully apparent with the emergence of polyomavirus-associated nephropathy in kidney-transplant recipients, with a prevalence rate of up to 10%. In most cases, high BK virus replication in tubular epithelial cells causes significant cytopathology, leading to permanently impaired renal allograft function and return to hemodialysis within 6-60 months. In 5-10% of allogenic bone marrow/hematopoietic stem cell transplant recipients, high-level BK virus replication in the ureter/bladder mucosa has been associated with postengraftment hemorrhagic cystitis, which appears to involve significant immunopathology. Thus, in view of the increasing clinical need, a number of drugs have been studied in small case series. We review the antiviral strategies explored to date and specifically discuss available in vivo and in vitro data on cidofovir, leflunomide, fluoroquinolones and intravenous immunoglobulins, regarding mechanism, administration, dosing and outcome and provide a perspective on future therapy options.

Evaluation and management of BK virus-associated nephropathy following allogeneic hematopoietic cell transplantation

BK virus nephropathy is a common cause of graft loss in kidney transplant recipients. Cases of BK nephropathy following allogeneic hematopoietic cell transplantation (HCT) are underreported. An increased incidence of BK virus-associated nephropathy is being seen in the setting of more profound and prolonged immunosuppression following solid organ transplantation and HCT. We will review diagnostic and treatment modalities for BK-associated nephropathy following allogeneic HCT.

Hematuria due to adenoviral infection in bone marrow transplant recipients

Late-onset hemorrhagic cystitis (HC) caused by adenovirus (AdV) infection is a common complication in hematopoietic stem cell transplantation (HSCT) recipients. However, limited information exists regarding adenovirus-associated HC. We report a retrospective study of 84 hematopoietic stem cell transplant recipients that evaluated the incidence and risk factors for AdV-induced HC. The development of HC was strongly related to adenoviral infection (P = .004). Among 13 patients who developed late-onset HC, AdVs were identified as a causative agent in 10 cases. AdV preferentially affected younger (P = .013) and male patients. Affected subjects had been transplanted for either malignant (7/10) or nonmalignant disorders (3/10). Most cases of AdV-hematuria were self-limited single or recurrent mild hemorrhagic episodes (P = .000), occurring at a median of 41 days after transplantation and lasting an average of 4 days. Viral load in patients with AdV-induced HC was similar to infected subjects who did not develop HC (2.5 × 10(3) vs 3.4 × 10(3) copies/mL). We HC occurring before 200 days was associated with a greater risk of a fatal outcome (P = .002) but occurrence of AdV infection did not affect a patient's survival. Our study confirmed the suggestion that non-AdV coinfections may worsen the course of AdV-HC.

Low-dose cidofovir in the treatment of symptomatic BK virus infection in patients undergoing allogeneic hematopoietic stem cell transplantation: a retrospective analysis of an algorithmic approach

BK virus (BKV) reactivation occurs in 50% of allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Standardized antiviral management of BKV infection has not been established. In order to develop a uniform guideline, a treatment algorithm for the management of symptomatic BKV replication was implemented for our allo-HSCT population. This is a retrospective analysis of patients treated according to the protocol between January 2008 and January 2009. Eighteen patients developed symptomatic BKV replication a median of 43 days after allo-HSCT. All patients had BK viruria and 12 patients had BK viremia in addition to viruria. Patients with isolated viruria were treated with intravenous (IV) low-dose cidofovir (0.5-1mg/kg IV weekly) until symptom resolution. In patients with BK viremia, therapy was continued until virological clearance was achieved in the blood. Four patients also received intravesical instillation of cidofovir per physician discretion. Thirteen of 18 (72%) patients with viruria and 8 of 12 (75%) patients with viremia responded to treatment. Three patients developed transient renal dysfunction. Low-dose cidofovir is safe and effective in allo-HSCT recipients. In absence of randomized prospective data, an institutional algorithmic protocol removes variance in practice pattern and derives data that may be used for research and improved patient care.

Haemorrhagic cystitis and polyomavirus JC infection in ataxia telangiectasia

We report the case of a young adolescent with ataxia telangiectasia (AT) and life-threatening haemorrhage from the bladder due to a combination of bladder wall telangiectasis, immunosuppressive therapy and an infection with polyomavirus JC. BK and JC are both members of the polyomavirus family. BK virus is a known cause of haemorrhagic cystitis in bone-marrow and nephropathy in kidney transplant patients, whereas JC virus is mainly associated with progressive multifocal leukoencephalopathy and only rarely found in haemorrhagic cystitis. Although opportunistic infections are uncommon in AT and virus replication was described as being down-regulated in ATM (AT mutated protein)-deficient cells, clinicians should be aware that severe haematuria in a patient with AT and undergoing immunosuppressive therapy is suggestive for polyomavirus JC-induced haemorrhagic cystitis.

High frequency and diversity of rearrangements in polyomavirus bk noncoding regulatory regions cloned from urine and plasma of Israeli renal transplant patients and evidence for a new genetic subtype

Polyomavirus BK (BKV) establishes latent infection in various human tissues, including the kidney. Reactivation following renal transplantation (RT) may cause BKV-associated nephropathy, leading to graft loss. BKV reactivation is often associated with extensive rearrangements in the BKV noncoding regulatory region (NCRR). We explored the formation and predominance of the rearrangements versus the diversity of the rearrangements by cloning and characterizing PCR-amplified NCRR sequences from six Israeli RT patients. We found a high frequency and a high degree of diversity of rearrangements: NCRRs that contained major rearrangements (mrNCRRs), including large insertions and deletions, were detected in 0 to 100% of the clones from individual samples (mean, 50% and 67% in plasma and urine, respectively). In addition, we found a high frequency of mrNCRRs that contained single-nucleotide variations (snvNCRRs) among identical mrNCRRs and archetype clones. mrNCRRs were present in plasma and in concomitantly collected urine samples, but for each patient, only a subset of the mrNCRRs and snvNCRRs were present in both compartments at the same time and/or in subsequent samples from the same compartment. Some mrNCRRs were observed over several months, indicating the continuous replication of the viral genomes carrying them. Phylogenetic analysis based on the snvNCRR in the archetype clones grouped isolates from four of the patients into a new subgroup of genotype IV. Genotypes Ib-1 and Ib-2 were also found. Isolates from two patients had NCRRs from two genotypes, one concurrently with a RT and one after a second RT. Our study prompts further investigation of the functional consequences of NCRR rearrangements to assess their biological significance and their putative role in disease progression and prognosis.

Human alpha-defensins inhibit BK virus infection by aggregating virions and blocking binding to host cells

BK virus (BKV) is a polyomavirus that establishes a lifelong persistence in most humans and is a major impediment to success of kidney grafts. The function of the innate immune system in BKV infection and pathology has not been investigated. Here we examine the role of antimicrobial defensins in BKV infection of Vero cells. Our data show that alpha-defensin human neutrophil protein 1 (HNP1) and human alpha-defensin 5 (HD5) inhibit BKV infection by targeting an early event in the viral lifecycle. HD5 treatment of BKV reduced viral attachment to cells, whereas cellular treatment with HD5 did not. Colocalization studies indicated that HD5 interacts directly with BKV. Ultrastructural analysis revealed HD5-induced aggregation of virions. HD5 also inhibited infection of cells by other related polyomaviruses. This is the first study to demonstrate polyomavirus sensitivity to defensins. We also show a novel mechanism whereby HD5 binds to BKV leading to aggregation of virion particles preventing normal virus binding to the cell surface and uptake into cells.

Progressive multifocal leukoencephalopathy: report of three cases in HIV-negative hematological patients and review of literature

Progressive multifocal leukoencephalopathy (PML) is a central nervous system (CNS) disease usually observed in immunodeficient patients, especially human immunodeficiency virus (HIV)-positive, caused by John Cunningham virus. This infectious complication has been described in many HIV-negative hematological patients, especially affected by lymphoproliferative diseases. PML has been observed after both chemotherapy and bone marrow transplantation and, recently, in association with rituximab. Diagnosis can be complicated, and often a CNS biopsy is required. Current treatment approaches are not effective in both HIV-positive and HIV-negative patients, and the outcome remain very poor in the majority of cases, even after combination therapies. We report three cases of PML in hematological patients, treated respectively with conventional chemotherapy and autologous and haploidentical transplantation, and review the literature on PML. All of them received rituximab, which has recently been in the focus of a Food and Drug Administration warning.

Treating multiple sclerosis with monoclonal antibodies

Therapeutic monoclonal antibodies (mAbs) are potent new tools for a molecular targeted approach to modify the course of multiple sclerosis (MS). Besides natalizumab, which was approved in 2006, three other mAbs (alemtuzumab, rituximab and daclizumab) were successfully tested in Phase II MS trials. In this review, introductory notes on the development and systematic nomenclature of therapeutic mAbs in general, set the stage for a detailed discussion of the four mAbs mentioned. We summarize non-MS indications, expression and function of target antigens, scientific rationales for MS therapy, putative modes of action and pharmacological aspects. Particularly, we provide a critical discussion of clinical MS trials, including protocols and interim analyses of trials currently underway. The natalizumab section pays special attention to the clinical handling of safety issues and the diagnostic use of neutralizing antibodies. We finally develop a scenario for how each of the four mAbs might evolve into the market of MS therapeutics within the coming years.

Polyomavirus BK infection in blood and marrow transplant recipients

The association of BK virus infection with hemorrhagic cystitis in blood and marrow transplant (BMT) recipients was first demonstrated two decades ago. During this time, therapeutic interventions focused on supportive measures such as hyperhydration, continuous bladder irrigation and topical administration of agents that alter the mucosal surface of the bladder wall. In recent years, PCR amplification of viral DNA in the urine and plasma has solidified the association of BK virus infection with hemorrhagic cystitis, demonstrating that higher urine and plasma viral loads occur in the setting of disease. The evaluation of virus-specific therapy has lagged behind assessment of the viral load and theories of pathogenesis. Extrapolating from successes in the treatment of BK virus nephropathy in the renal transplant population, cidofovir and leflunomide are identified as potential effective agents for the treatment of BK virus-associated hemorrhagic cystitis. The fluoroquinolone antibiotics may prove to be effective as prophylactic agents. Given the manifestation of BK virus infection in organs outside of the urinary tract in an increasing immunocompromised patient population and the availability of potential antiviral agents, therapeutic trials need to progress beyond the small case series in order to improve the morbidity and mortality caused by BK virus-associated hemorrhagic cystitis in the BMT population.

Polyomavirus BK infection in blood and marrow transplant recipients

The association of BK virus infection with hemorrhagic cystitis in blood and marrow transplant (BMT) recipients was first demonstrated two decades ago. During this time, therapeutic interventions focused on supportive measures such as hyperhydration, continuous bladder irrigation and topical administration of agents that alter the mucosal surface of the bladder wall. In recent years, PCR amplification of viral DNA in the urine and plasma has solidified the association of BK virus infection with hemorrhagic cystitis, demonstrating that higher urine and plasma viral loads occur in the setting of disease. The evaluation of virus-specific therapy has lagged behind assessment of the viral load and theories of pathogenesis. Extrapolating from successes in the treatment of BK virus nephropathy in the renal transplant population, cidofovir and leflunomide are identified as potential effective agents for the treatment of BK virus-associated hemorrhagic cystitis. The fluoroquinolone antibiotics may prove to be effective as prophylactic agents. Given the manifestation of BK virus infection in organs outside of the urinary tract in an increasing immunocompromised patient population and the availability of potential antiviral agents, therapeutic trials need to progress beyond the small case series in order to improve the morbidity and mortality caused by BK virus-associated hemorrhagic cystitis in the BMT population.

Polyomaviruses and human diseases

Polyomaviruses are small, nonenveloped DNA viruses, which are widespread in nature. In immunocompetent hosts, the viruses remain latent after primary infection. With few exceptions, illnesses associated with these viruses occur in times of immune compromise, especially in conditions that bring about T cell deficiency. The human polyomaviruses BKV and JCV are known to cause, respectively, hemorrhagic cystitis in recipients of bone marrow transplantation and progressive multifocal leukoencephalopathy in immunocompromised patients, for example, by HIV infection. Recently, transplant nephropathy due to BKV infection has been increasingly recognized as the cause for renal allograft failure. Quantitation of polyomavirus DNA in the blood, cerebrospinal fluid, and urine, identification of virus laden "decoy cells" in urine, and histopathologic demonstration of viral inclusions in the brain parenchyma and renal tubules are the applicable diagnostic methods. Genomic sequences of polyomaviruses have been reported to be associated with various neoplastic disorders and autoimmune conditions. While various antiviral agents have been tried to treat polyomavirus-related illnesses, current management aims at the modification and/or improvement in the hosts' immune status. In this chapter, we provide an overview of polyomaviruses and briefly introduce its association with human diseases, which will be covered extensively in other chapters by experts in the field.

Discovery and epidemiology of the human polyomaviruses BK virus (BKV) and JC virus (JCV)

Although discovered over thirty years ago, many aspects of the epidemiology of BKV and JCV in the general population, such as the source of infectious virus and the mode of transmission, are still unknown. Primary infection with both BKV and JCV is usually asymptomatic, and so age seroprevalence studies have been used to indicate infection. BKV commonly infects young children in all parts of the world, with the exception of a few very isolated communities, adult seroprevalence rates of 65-90% being reached by the age of ten years. In contrast, the pattern of JCV infection appears to vary between populations; in some anti-JCV antibody is acquired early as for BKV, but in others anti-JCV antibody prevalence continues to rise throughout life. This indicates that the two viruses are probably transmitted independently and by different routes. Whilst BKV DNA is found infrequently in the urine of healthy adults, JCV viruria occurs universally, increasing with age, with adult prevalence rates often between 20% and 60%. Four antigenic subtypes have been described for BKV and eight genotypes are currently recognized for JCV. The latter have been used to trace population movements and to reconstruct the population history in various communities.

Relationship of pretransplantation polyoma BK virus serologic findings and BK viral reactivation after hematopoietic stem cell transplantation

BACKGROUND

Reactivation of polyoma BK virus (BKV) infection is consistently associated with hemorrhagic cystitis in persons who undergo hematopoietic stem cell transplantation (HSCT). In this study, we examined the relationship of reactivation of BKV infection with pre-HSCT serologic findings of BKV antibody.

METHODS

Serial urine samples (n=1118) obtained from 140 HSCT recipients were prospectively obtained, and BKV loads were quantified by quantitative polymerase chain reaction. Pre-HSCT anti-BKV immunoglobulin G (IgG) levels were determined by indirect immunofluorescence.

RESULTS

In 68 patients, there was significant peaking (i.e., > or = 3-log increase) in the urine BKV load (median peak, 1.7x10(9) copies/mL; range, 1.1x10(4) to 3.2x10(14) copies/mL) occurring at a median time of 24.5 days (range, 7-49 days). In 72 patients, low-level BKV viruria occurred without peaking (median BKV load, 10 copies/mL; range, 9.9x10(3) to 1.2x10(10) copies/mL) at a median time of 24.5 days (range, 7-49 days). Pre-HSCT anti-BKV IgG was positively related to elevated urine BKV load during HSCT (P<.001). Binary logistic regression revealed that pre-HSCT anti-BKV IgG level was the only statistically significant factor (P=.009) to be associated with a > or = 3-log increase in the peak urine BKV load (positive and negative predictive values, 69% and 68%, respectively). Nine patients developed hemorrhagic cystitis at a median of 56 days (range, 29-160); 7 of these patients were evaluable and were found to have a > or = 3-log increase in the peak BKV load. In binary logistic regression, peaking of the urine BKV load (P=.026) and graft-versus-host disease (P=.033) were found to be statistically significant risks for hemorrhagic cystitis.

CONCLUSIONS

The identification of the serologic status of BKV as a significant risk factor for BKV viruria suggests that it should be included as an integral part of the pre-HSCT evaluation.

Risk factors and treatment of hemorrhagic cystitis in children who underwent hematopoietic stem cell transplantation

A retrospective cohort of 163 children with 171 hematopoietic stem cell transplantation (HSCT) performed during Mar. 1992-Dec. 2005 were analyzed to evaluate the incidence, risk factors, management, and outcome of hemorrhagic cystitis (HC). Fourteen patients (8.2%) developed HC (6 boys, median age 6.6 years) at 0-166 days after HSCT (median 25 days), and lasted for 3-96 days (median 26 days). Older age at transplant (median 11.0 vs. 6.4 years, P = 0.013), allogeneic transplant (OR = 4.4, P = 0.02), cyclophosphamide-containing conditioning (OR = 4.87, P = 0.008), moderate-to-severe acute graft-versus-host disease (GVHD) (OR = 3.56, P = 0.025) and hepatic GVHD (OR = 3.62, P = 0.017) were associated with higher risks of HC in univariate but not multivariate analyses. While estrogen was ineffective in most patients, intravesical formalin, which was used in five patients, was found to be a very effective yet safe treatment for intractable HC. Patients with HC had longer hospital stay (median 175 vs. 88 days, P = 0.004). HC resolved after treatments in all cases but eight of the 14 patients subsequently died of other complications of HSCT. In conclusion, HC is a serious complication of allogeneic HSCT. Treatment with intravesical formalin appears effective and safe and can be considered early in severe HC to reduce the risk of morbidity and mortality.

Isolated heart and liver transplant recipients are at low risk for polyomavirus BKV nephropathy

BACKGROUND

BKV infection and nephropathy is a significant cause of allograft dysfunction in kidney transplantation. BKV viremia, rather than viruria, corresponds to BKV nephropathy. The prevalence of BKV viremia in non-renal solid organ transplants has not been systematically evaluated.

METHODS

We determined prevalence of BKV viremia in kidney, combined kidney-heart, kidney-liver, kidney-pancreas, kidney-heart-liver, and heart and liver transplant recipients using BKV-PCR.

RESULTS

Seven out of 173 (4%) kidney transplant recipients had BKV viremia, with BKV>2 x 10(5) copies/mL in 6/7 and 1.9 x 10(3) in the remaining one patient. BKV viremia was not found in 24 heart transplant recipients, whereas 1/37 (2.7%) liver transplants showed low copy numbers (< or =10(3)). BKV-PCR< or =10(3) copies/mL were also found in one of each combined kidney-heart and kidney-liver transplant recipients. BKV nephropathy was proven by biopsy in 4/6 patients with high BKV viral loads. All six patients showed renal dysfunction, requiring reduction in immunosuppression and antiviral therapy. All four patients with low BKV viral loads (1.9 x 10(3) or < or =10(3)) showed stable renal function after reduction of immunosuppression or no treatment, respectively.

CONCLUSION

Higher BKV levels in plasma are associated with renal dysfunction. Kidney transplant recipients are at high risk compared with recipients of isolated heart or liver allografts, for development of BKV nephropathy.

Detection of BK virus and adenovirus in the urine from children after allogeneic stem cell transplantation

The development of hemorrhagic cystitis (HC) and urinary excretion of polyoma BK virus (BKV) and adenovirus (ADV) was investigated by polymerase chain reaction in 20 children undergoing allogeneic stem cell transplantation. Five children developed HC, and all of them excreted BKV; however, only 1 excreted ADV, suggesting that BKV is more significant cause of HC than ADV in children undergoing stem cell transplantation.

Incidence, clinical outcome, and management of virus-induced hemorrhagic cystitis in children and adolescents after allogeneic hematopoietic cell transplantation

We analyzed the incidence, etiology, risk factors, and clinical management of hemorrhagic cystitis (HC) in 102 children who underwent allogeneic stem cell transplantation: 28 from matched siblings, 57 from unrelated donors, and 17 from mismatched relatives. Conditioning regimens consisted of high-dose chemotherapy (n=83) or total body irradiation (n=19). In all children, urine and plasma were prospectively screened for human polyomavirus (HPV; BK virus [BKV] and JC virus [JCV]) or adenovirus (AdV) DNA with a polymerase chain reaction-based assay. Viral DNA was detected in the urine of 56 children (54.9%): BKV in 48 (47%), JCV in 4 (3.9%), and AdV in 4 (3.9%). HC occurred in 26 children (25.5%), and viruria was detected in all of them: BKV in 21 (80.8%), AdV in 4 (14.4%), and JCV in 1 (3.8%). All patients with AdV viruria developed HC. The cumulative incidence of HC in patients with HPV viruria was 0.43. The only significant risk factor for HC in patients with HPV-positive urine was conditioning with high-dose chemotherapy. Twenty-two children were treated with cidofovir, with no significant toxicity. In all treated patients but 1, the clinical symptoms were moderate, and no HC-related death was observed. We conclude that virus-induced HC is a frequent complication after allogeneic hematopoietic cell transplantation. Treatment with cidofovir is feasible, and further studies are warranted to evaluate its activity in HC mediated by BKV or JCV.

Specific and quantitative detection of human polyomaviruses BKV, JCV, and SV40 by real time PCR

BACKGROUND

The polyomaviruses that infect humans, BK virus (BKV), JC virus (JCV), and simian virus 40 (SV40), typically establish subclinical persistent infections. However, reactivation of these viruses in immunocompromised hosts is associated with renal nephropathy and hemorrhagic cystitis (HC) caused by BKV and with progressive multifocal leukoencephalopathy (PML) caused by JCV. Additionally, SV40 is associated with several types of human cancers including primary brain and bone cancers, mesotheliomas, and non-Hodgkin's lymphoma. Advancements in detection of these viruses may contribute to improved diagnosis and treatment of affected patients.

OBJECTIVE

To develop sensitive and specific real time quantitative polymerase chain reaction (RQ-PCR) assays for the detection of T-antigen DNA sequences of the human polyomaviruses BKV, JCV, and SV40 using the ABI Prism 7000 Sequence Detection System.

STUDY DESIGN

Assays for absolute quantification of the viral T-ag sequences were designed and the sensitivity and specificity were evaluated. A quantitative assay to measure the single copy human RNAse P gene was also developed and evaluated in order to normalize viral gene copy numbers to cell numbers.

RESULTS

Quantification of the target genes is sensitive and specific over a 7 log dynamic range. Ten copies each of the viral and cellular genes are reproducibly and accurately detected. The sensitivity of detection of the RQ-PCR assays is increased 10- to 100-fold compared to conventional PCR and agarose gel protocols. The primers and probes used to detect the viral genes are specific for each virus and there is no cross reactivity within the dynamic range of the standard dilutions. The sensitivity of detection for these assays is not reduced in human cellular extracts; however, different DNA extraction protocols may affect quantification.

CONCLUSION

These assays provide a technique for rapid and specific quantification of polyomavirus genomes per cell in human samples.

Emerging viral infections after hematopoietic cell transplantation

This overview summarizes recent data on emerging viruses after hematopoietic cell transplantation (HCT), including adenovirus, BK virus, human metapneumovirus (hMPV), and human herpesvirus (HHV) 6. The increased recognition of these infections is due to improved molecular detection methods, increased surveillance and more profound immunosuppression in the host. Adenovirus can cause serious disease especially in T-cell depleted transplant recipients. Adenovirus viremia is an important risk factor for disease in this setting. BK virus has been associated with hemorrhagic cystitis in HCT recipients. BK viremia is significantly associated with hemorrhagic cystitis. hMPV shows a seasonal distribution and can cause fatal pneumonia in HCT recipients. hMPV may be the etiology of some cases previously categorized as idiopathic pneumonia syndrome. HHV-6 commonly leads to viremia in HCT recipients. HHV-6 has been strongly associated with encephalitis and delayed platelet engraftment. Prospective studies are needed to further examine epidemiology, disease associations, and management strategies for these viruses.

Fluoroquinolone resistance in hematopoietic stem cell transplant recipients with infectious complications

The infectious complications are an important cause of morbidity and mortality in hematopoietic stem cell transplant (HSCT) recipients. Our retrospective study has the objective to evaluate the incidence, clinical and bacteriologic features of documented infections in these patients. The frequency of infectious complications was analysed in 42 patients with hematologic malignancies who received HSCT from January to December 2002 at Pisa General Hospital. Thirty-three patients underwent autologous HSCT and 9 received allogeneic HSCT. All patients received acyclovir, fluconazole and fluoroquinolones as prophylactic regimen. A total of 38 infectious episodes were recognized in 22 patients during the early post-HSCT period (N=27) and in the late post-HSCT period (N=11). Infectious complications rate correlated positively with the deepness and length of neutropenia in the early period. There were 21 episodes of sepsis (the majority by coagulase negative staphylococci), 2 pneumonias and 1 vertebral osteomyelitis. All staphylococcus strains were, in vitro, resistant to oxacillin and ciprofloxacin and 8 out of 15 gram negative rods were resistant to ciprofloxacin. Most of the infectious complications were cured with appropriated antimicrobial therapy and/or with engraftment and, in 4 cases, with central catheter removal. One patient developed a positive CMV antigenemia; a pre-core mutant form of HBV reactivation was diagnosed in another patient. No cases of invasive fungal infections were recognised. Five patients died but only one from infection (septic shock). Pneumonia was a coexisting cause of death in 2 patient in the late period. We can conclude that most of infectious complications, that occurred in the early period post-HSCT were due to coagulase negative staphylococci and gram negative rods resistant to ciprofloxacin. For this reason, the usefulness of fluoroquinolone prophylaxis in HSCT recipients should be reevaluated.

Detection and quantitation of BK virus DNA by real-time polymerase chain reaction in the LT-ag gene in adult renal transplant recipients

Determination of polyomavirus BK (BKV) load in urine and plasma has been advocated for monitoring adult renal transplant recipients suffering from BKV-related nephropathy. An "in-house" real-time quantitative PCR assay was developed using the BKV-1/BKV-3 primers set in the large tumor antigen (LT-ag) region to quantitate BK virus loads in plasma and urine in renal transplant patients. This assay was adapted to routine virology laboratory by evaluating two extraction procedures of nucleic acids from urine and plasma, one manual and the other using an automatic extractor, and by evaluating the Light Cycler versus Taqman apparatus. Both the manual and automatic extraction procedures and real-time PCR apparatus were equivalent. The Light Cycler and Taqman instruments allow similarly rapid, accurate, reproducible and specific quantitative detection of the three major BKV subtypes, with a detection limit of 10 BKV DNA copies/ml, and a range from 10(0) to 10(7) copies/ml. Of 855 renal transplant patients, 128 (15%) had BKV DNA in both plasma and urine samples with a mean viral load of 5.1 log/ml in plasma and 6.8 log/ml in urine and in 5 (4%) BKV-associated tubulo-interstitial nephropathy; 332 (39%) BKV DNA was found only in the urine, not in the plasma, without further development of nephropathy and 395 patients had no BKV in plasma and urine. These observations emphasize the usefulness of real-time PCR to assess the BKV load by routine testing, and confirm the need to combine both plasma and urine determinations of the BKV DNA load in order to identify renal transplant patient at high risk for BKV-associated nephropathy.

Successful outcome of progressive multifocal leukoencephalopathy in a renal transplant patient

We report the case of a 47-year-old man who developed progressive multifocal leukoencephalopathy (PML) after receiving immuno-suppressive therapy for renal transplantation. The patient presented with a focal seizure and cognitive changes 5 months post-transplantation. He was found to have enhancing lesions in the parietal lobe and typical findings of PML in a brain biopsy. Immunosuppression was discontinued and the neurological symptoms gradually resolved over a period of 4 weeks. The patient is free of any neurological symptoms 36 months after the diagnosis of PML and imaging studies demonstrate resolution of the PML lesions. The patient returned to hemodialysis 3 months after immunosuppression was discontinued. We also present a review of the literature on PML in renal transplant recipients.

Urinary tract infection in children: etiology and epidemiology

The urinary tract is a relatively common site of infection in infants and young children. Urinary tract infection (UTI) may result in significant acute morbidity, as well as longterm medical complications. Recent advances elucidating the pathogen-host interaction have broadened the understanding of the pathogenesis and clinical progression of pediatric UTI. This article focuses on the epidemiology and pathogenesis of pediatric UTI, and briefly discusses UTI-related complications.

Cytomegalovirus-induced haemorrhagic cystitis in a patient with neurogenic bladder

We report a case of severe cytomegalovirus induced haemorrhagic cystitis associated with neurogenic urinary bladder in a patient suffering from anaplastic spinal ependymoma. The diagnosis was established by bladder biopsy and immunohistochemical study. Haematuria resolved after ganciclovir therapy. Previous reports are reviewed.

Simultaneous detection and differentiation of human polyomaviruses JC and BK by a rapid and sensitive PCR-ELAHA assay and a survey of the JCV subtypes within an Australian population

Human polyomaviruses JCV and BKV can cause several clinical manifestations in immunocompromised hosts, including progressive multifocal leukoencephalopathy (PML) and haemorrhagic cystitis. Molecular detection by polymerase chain reaction (PCR) is recognised as a sensitive and specific method for detecting human polyomaviruses in clinical samples. In this study, we developed a PCR assay using a single primer pair to amplify a segment of the VP1 gene of JCV and BKV. An enzyme linked amplicon hybridisation assay (ELAHA) using species-specific biotinylated oligonucleotide probes was used to differentiate between JCV and BKV. This assay (VP1-PCR-ELAHA) was evaluated and compared to a PCR assay targeting the human polyomavirus T antigen gene (pol-PCR). DNA sequencing was used to confirm the polyomavirus species identified by the VP1-PCR-ELAHA and to determine the subtype of each JCV isolate. A total of 297 urine specimens were tested and human polyomavirus was detected in 105 specimens (35.4%) by both PCR assays. The differentiation of JCV and BKV by the VP1-PCR-ELAHA showed good agreement with the results of DNA sequencing. Further, DNA sequencing of the JCV positive specimens showed the most prevalent JCV subtype in our cohort was 2a (27%) followed by 1b (20%), 1a (15%), 2c (14%), 4 (14%) and 2b (10%). The results of this study show that the VP1-PCR-ELAHA is a sensitive, specific and rapid method for detecting and differentiating human polyomaviruses JC and BK and is highly suitable for routine use in the clinical laboratory.

Polyomavirus BK

Polyomavirus hominis 1, better known as BK virus (BKV), infects up to 90% of the general population. However, significant clinical manifestations are rare and limited to individuals with impaired immune functions. BKV has been associated with diverse entities such as haemorrhagic cystitis, ureteric stenosis, vasculopathy, pneumonitis, encephalitis, retinitis, and even multi-organ failure. In addition, BKV has been implicated in autoimmune disease and possibly cancer. Due to high prevalence and frequent reactivation, the role of BKV in some of these pathologies has been difficult to define. Development of BKV diseases is likely to require complementing determinants in the host, the target organ, and possibly the virus, that are subject to modulators such as immunosuppression. These complex aspects are highlighted in polyomavirus-associated nephropathy (PAN), an emerging disease in renal allograft recipients that may jeopardise the progress in renal transplantation accomplished in the past 10 years. Intervention is difficult due to the lack of specific antivirals and relies mostly on improving immune control. Diagnostic strategies using urine cytology and BKV load measurements in plasma have led to earlier diagnosis of PAN, which increased the success rate of intervention. Case series suggest that cidofovir might be effective, especially when combined with reduced immunosuppression.

Successful cidofovir treatment of adenovirus-associated hemorrhagic cystitis and renal dysfunction after allogenic bone marrow transplant

We present a patient who developed hemorrhagic cystitis and renal dysfunction after unrelated bone marrow transplantation. Polyoma BK virus and adenovirus 11 were detected in the urine. Vidarabine was administered without effect. Relatively low dose cidofovir was efficacious. Renal function improved, and the urinary secretion of adenovirus stopped.