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

Longitudinal Detection of Twenty DNA and RNA Viruses in Allogeneic Hematopoietic Stem Cell Transplant Recipients Plasma

Metagenomics revealed novel and routinely overlooked viruses, representing sources of unrecognized infections after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We aim to describe DNA and RNA virus prevalence and kinetics in allo-HSCT recipients' plasma for one year post HSCT. We included 109 adult patients with first allo-HSCT from 1 March 2017 to 31 January 2019 in this observational cohort study. Seventeen DNA and three RNA viral species were screened with qualitative and/or quantitative r(RT)-PCR assays using plasma samples collected at 0, 1, 3, 6, and 12 months post HSCT. TTV infected 97% of patients, followed by HPgV-1 (prevalence: 26-36%). TTV (median 3.29 × 10⁵ copies/mL) and HPgV-1 (median 1.18 × 10⁶ copies/mL) viral loads peaked at month 3. At least one Polyomaviridae virus (BKPyV, JCPyV, MCPyV, HPyV6/7) was detected in >10% of patients. HPyV6 and HPyV7 prevalence reached 27% and 12% at month 3; CMV prevalence reached 27%. HSV, VZV, EBV, HHV-7, HAdV and B19V prevalence remained <5%. HPyV9, TSPyV, HBoV, EV and HPg-V2 were never detected. At month 3, 72% of patients had co-infections. TTV and HPgV-1 infections were highly prevalent. BKPyV, MCPyV and HPyV6/7 were frequently detected relative to classical culprits. Further investigation is needed into associations between these viral infections and immune reconstitution or clinical outcomes.

Kidney injury and disease in patients with haematological malignancies

Acute kidney injury (AKI) is common in patients with cancer, especially in those with haematological malignancies. Kidney injury might be a direct consequence of the underlying haematological condition. For example, in the case of lymphoma infiltration or extramedullary haematopoiesis, it might be caused by a tumour product; in the case of cast nephropathy it might be due to the presence of monoclonal immunoglobulin; or it might result from tumour complications, such as hypercalcaemia. Kidney injury might also be caused by cancer treatment, as many chemotherapeutic agents are nephrotoxic. High-intensity treatments, such as high-dose chemotherapy followed by haematopoietic stem cell transplantation, not only increase the risk of infection but can also cause AKI through various mechanisms, including viral nephropathies, engraftment syndrome and sinusoidal obstruction syndrome. Some conditions, such as thrombotic microangiopathy, might also result directly from the haematological condition or the treatment. Novel immunotherapies, such as immune checkpoint inhibitors and chimeric antigen receptor T cell therapy, can also be nephrotoxic. As new therapies for haematological malignancies with increased anti-tumour efficacy and reduced toxicity are developed, the number of patients receiving these treatments will increase. Clinicians must gain a good understanding of the different mechanisms of kidney injury associated with cancer to better care for these patients.

Beyond Cytomegalovirus and Epstein-Barr Virus: a Review of Viruses Composing the Blood Virome of Solid Organ Transplant and Hematopoietic Stem Cell Transplant Recipients

Viral primary infections and reactivations are common complications in patients after solid organ transplantation (SOT) and hematopoietic stem cell transplantation (HSCT) and are associated with high morbidity and mortality. Among these patients, viral infections are frequently associated with viremia. Beyond the usual well-known viruses that are part of the routine clinical management of transplant recipients, numerous other viral signatures or genomes can be identified in the blood of these patients. The identification of novel viral species and variants by metagenomic next-generation sequencing has opened up a new field of investigation and new paradigms. Thus, there is a need to thoroughly describe the state of knowledge in this field with a review of all viral infections that should be scrutinized in high-risk populations. Here, we review the eukaryotic DNA and RNA viruses identified in blood, plasma, or serum samples of pediatric and adult SOT/HSCT recipients and the prevalence of their detection, with a particular focus on recently identified viruses and those for which their potential association with disease remains to be investigated, such as members of the Polyomaviridae, Anelloviridae, Flaviviridae, and Astroviridae families. Current knowledge of the clinical significance of these viral infections with associated viremia among transplant recipients is also discussed. To ensure a comprehensive description in these two populations, individuals described as healthy (mostly blood donors) are considered for comparative purposes. The list of viruses that should be on the clinicians' radar is certainly incomplete and will expand, but the challenge is to identify those of possible clinical significance.

Antiviral Therapies for Herpesviruses: Current Agents and New Directions

PURPOSE

The objective of this review was to summarize the recent literature describing the current burden of disease due to herpesviruses in the antiviral and transplant era; describe mechanisms of action of antiviral agents and the development of resistance; summarize the literature of recent antiviral agents brought to market as well as agents under development; and to present literature on future strategies for herpesvirus therapeutics.

METHODS

An extensive search of the medical literature related to antiherpesviral therapy was conducted to compose this narrative review. Literature searches were performed via PubMed and ultimately 137 articles were included as most relevant to the scope of this article.

FINDINGS

Herpesviruses are a family of DNA viruses that are ubiquitous throughout human populations and share the feature of establishing lifelong infections in a latent phase with the potential of periodic reactivation. With the exception of herpes simplex virus, varicella zoster virus, and Epstein-Barr virus, which have a significant disease burden in individuals with normal immune function, the morbidity and mortality of the remaining viruses are primarily associated with the immunocompromised host. Over the last half-century, several agents have been tested in large randomized, placebo-controlled trials that have resulted in safe and effective antiviral agents for the treatment of many of these infections.

IMPLICATIONS

With increasing use of antiherpesviral agents for extended periods, particularly in immunocompromised hosts, the emergence of resistant viruses has necessitated the development of newer agents with novel targets and better side-effect profiles.

Adenovirus

Adenoviruses are a highly prevalent infection that can cause a range of clinical syndromes in immunocompromised patients, ranging from localized disease of the respiratory tract, gastrointestinal tract, or urinary tract to disseminated disease. Adenovirus infections may develop in this unique population as the result of primary infection or reactivation of latent virus. Disease can be potentially progressive with high rates of mortality in patients with pneumonia and disseminated disease. Fortunately, cidofovir and its lipid ester, brincidofovir, appear to be effective for the treatment of adenovirus, although neither is specifically approved for this indication. Adenovirus should always be considered when immunocompromised patients present with any clinical syndrome that could be compatible with adenoviral infection. Once disease is suspected, cultures or molecular testing of appropriate specimens should be obtained and blood should be sent for adenovirus polymerase chain reaction (PCR) whenever adenovirus is suspected. Monitoring of quantitative viral loads in blood is helpful in predicting response to therapy with a significant drop (>1 log) associated with a higher probability of clinical response.

Therapeutic Basis of Vidarabine on Adenovirus-Induced Haemorrhagic Cystitis

When adenovirus causes haemorrhagic cystitis in immunocompromised patients, vidarabine is used for its treatment because therapeutic choice is limited. Although vidarabine has been reported to be effective for these patients, its therapeutic basis has not yet been established. Vidarabine dose-dependently inhibited viral replication as assessed by a yield reduction assay. Viral protein synthesis was dose-dependently inhibited by vidarabine but not at all by acyclovir, and the degree of inhibition by vidarabine was different for each of the viral proteins, ranging from 0–40% of the untreated control. These results indicated the specificity and mechanism of action of vidarabine against adenovirus. The concentration of vidarabine and its metabolite in the bladder is suggested to exhibit effective anti-adenoviral activity in suppressing the replication of adenovirus. Thus, our results support vidarabine therapy as a possible candidate for adenovirus-induced haemorrhagic cystitis in immunocompromised patients.

BK virus-hemorrhagic cystitis following allogeneic stem cell transplantation: Clinical characteristics and utility of leflunomide treatment

BK virus-hemorrhagic cystitis (BKV-HC) is a potential cause of morbidity and mortality in patients having undergone allogeneic stem cell transplantation (Allo-SCT). We analyzed the clinical features of BKV-HC following Allo-SCT and reported the utility of leflunomide therapy for BKV-HC.

MATERIALS AND METHODS

From January 2005 to June 2014, among the 69 patients underwent Allo-SCT in our institution, the patients who experienced BKV-HC were investigated retrospectively.

RESULTS

Hemorrhagic cystitis (HC) was observed in 30 patients (43.5%), and among them, 18 patients (26.1%) were identified as BKV-HC. The median age of the patients (12 males and 6 females) was 45 years (range, 13-63). Patients received Allo-SCT from acute myeloid leukemia (n=11), aplastic anemia (n=4), myelodysplastic syndrome (n=2), and non-Hodgkin lymphoma (n=1).The donor types were a HLA-matched sibling donor for 6 patients, HLA-matched unrelated donor for 9, and a haploidentical familial donor for 2. The median onset and duration of BKV-HC was on day 21 (range, 7-97) after transplantation and 22 days (range, 6-107). Eleven patients (62.1%) had grade I-II HC and seven patients (38.9%) had grade III-IV (high-grade) HC. Among the seven patients who had high-grade HC, one had complete response (CR), one partial response (PR), and five no response (NR). Among the five non-responders, one died of BKV-HC associated complications. The remaining four patients were treated with leflunomide, with achieving CR (n=2) and PR (n=2). The median duration from the start of leflunomide therapy to response was 13 days (range, 8-17 days). All patients tolerated the leflunomide treatment well, with three patients having mild gastrointestinal symptoms, including anorexia and abdominal bloating.

CONCLUSION

BKV-HC was commonly observed in patients with HC following Allo-SCT. In high-grade BKV-HC patients who fail supportive care, leflunomide may be a feasible option without significant toxicity.

[Hemorrhagic cystitis due to adenovirus in a renal transplant recipient: the first reported case in black Africa in a setting of a very beginning of a kidney transplantation program and review of the literature]

Viral infections are an important complication of transplantation. Polyomavirus are the commonest viruses that infect the renal allograft. Herpes virus nephropathy has also been described. In the past 15 years, adenovirus nephritis has emerged as a potentially life-threatening disease in renal transplant patients in developed countries. Most of the papers devoted to adenovirus nephritis are reported cases. The fate of such patients in resources-limited countries is not known. Herein, we describe the clinical, biological and prognostic findings of a black African transplanted patient with adenoviral hemorrhagic cystitis. This case is the very first of its kind reported in black Africa in a setting of a start of a renal transplantation pilot project. The patient is a 54-year-old man admitted at the nephrology service for gross haematuria and fever occurred 1 month after kidney transplantation. The diagnosis of adenoviral hemorrhagic cystitis has been suspected because the patient has displayed recurrent conjunctivitis and gastroenteritis well before transplantation, which was then confirmed by the real-time polymerase chain reaction performed on the blood. Conservatory measures associated with immunosuppression reduction have permitted the discontinuation of haematuria. This case has been discussed in regard of the epidemiology, the diagnosis, the treatment, the evolution and the prognosis of the adenoviral infection in the renal transplant patient. A review of the literature has been performed subsequently.

Cidofovir and brincidofovir reduce the pathology caused by systemic infection with human type 5 adenovirus in immunosuppressed Syrian hamsters, while ribavirin is largely ineffective in this model

There are no drugs approved specifically to treat disseminated adenovirus (Ad) infections in humans. Cidofovir is active against Ad in cell culture, and it is used frequently in the clinic with disseminated infection in pediatric transplant patients; however, controlled clinical studies have not been conducted to prove the anti-Ad efficacy of cidofovir. Brincidofovir, a lipid-linked derivative of cidofovir, which has strong activity against Ad in cell culture and in animal models, is a promising new drug currently in clinical trials. Ribavirin, which has modest activity against some Ad types in cell culture, has been used in the clinic against disseminated Ad, but the efficacy of ribavirin is unknown. In the current study, we have examined the activity of cidofovir, brincidofovir, and ribavirin against disseminated Ad5 infection in the immunosuppressed Syrian hamster model. Hamsters are immunosuppressed by treatment with cyclophosphamide, then infected intravenously with Ad5, leading to disseminated Ad5 infection, especially in the liver. We found that cidofovir and brincidofovir have excellent activity against Ad5 pathology and replication in the liver, even when administered therapeutically starting at 3 days post-challenge with Ad5. Ribavirin did not have anti-Ad5 activity in our model. Our data support the use of cidofovir and brincidofovir in humans for the treatment of disseminated Ad infections in humans.

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.

The kidney effects of hematopoietic stem cell transplantation

Hematopoietic stem cell transplant (HSCT) patients are at risk for acute kidney disease and CKD, which confer excess morbidity and mortality in this patient population. A main cause of acute kidney injury (AKI) in stem cell recipients is prerenal azotemia, but acute tubular necrosis (ATN), obstruction, marrow transfusion toxicity, and hepatic sinusoidal obstruction syndrome also contribute. AKI is an important risk factor for death and CKD among HSCT survivors. CKD is a growing complication of HSCT as more patients are transplanted and survival improves. For most patients, the exact etiology of CKD is never identified, but graft vs host disease and thrombotic microangiopathy are important diagnoses to consider. Stem cell transplant patient survival on dialysis is generally poor, but kidney transplantation is a safe and reasonable option for HSCT recipients who progress to ESRD.

Chronic kidney diseases in long-term survivors after allogeneic hematopoietic stem cell transplantation: monitoring and management guidelines

Chronic kidney disease (CKD) occurs commonly (prevalence of approximately 20% in a large series) after allogeneic hematopoietic stem cell transplantation (HSCT). There are three distinct clinical entities that occur after HSCT: thrombotic microangiopathy (TMA), nephrotic syndrome (NS), and idiopathic or graft-versus-host disease (GVHD)-related CKD. Acute renal function decline occurs in the majority of patients in the first months after transplantation. This acute kidney injury can persist and is a risk factor for the later development of CKD. However, the potentially independent role of GVHD, chronic inflammation, and chronic exposure to calcineurin inhibitors in the development and progression of CKD warrants further investigation. Careful monitoring of blood pressure, renal function, and proteinuria is mandatory in patients undergoing HSCT, especially older patients with pre-existent renal impairment. Renal function should be evaluated before HSCT and monitoring should occur at least every 6 to 12 months in these patients. Renal biopsies are indicated in patients with proteinuria and persistent or progressive rises in serum creatinine to determine etiology and prevent progression to end-stage renal disease (ESRD).

Donor-transmitted adenovirus infection causing kidney allograft nephritis and graft loss

Adenovirus (AdV) infection can occur early after transplantation, especially with potent immunosuppression for induction or acute rejection treatment. We present the largest case series of adult renal recipients from a single institution with AdV infection, and the first apparent case of transferred AdV infection from 1 deceased donor to 2 kidney recipients. Three patients received kidneys from 2 deceased donors: 2 from a 23-year-old donor, and the third from a 4-year-old donor. The recipients with the same donor both displayed early rejection. One who eventually lost his graft to AdV nephritis required treatment with plasmapheresis, intravenous immunoglobulin, rituximab, and anti-thymocyte globulin for severe antibody-mediated rejection. The second required only steroids for acute cellular rejection and has good renal function at 7 years. The third recipient was discovered to have AdV and microabscesess on renal biopsy and required nephrectomy. In the 2 cases of graft loss, we observed sudden deterioration of graft function with rising creatinine and subsequent necrosis resulting in nephrectomy within 40 days after transplantation. AdV was detected by polymerase chain reaction in urine or serum and/or renal tissue. AdV activation after potent immunosuppression can lead to systemic infection and may trigger rejection and/or early graft loss.

BK nephropathy in pediatric hematopoietic stem cell transplant recipients

BK nephropathy is a known cause of renal insufficiency in kidney transplant recipients. Activation of the polyoma virus may also occur in the native kidneys of non-renal allograft recipients. BK nephropathy has only been reported in a few patients after HCT, most being adult patients, and the single reported pediatric case had evidence of hemorrhagic cystitis. The response to antiviral therapy also seems to differ widely. Here, we describe two cases of BK nephropathy in the native kidneys of HCT recipients exposed to high levels of immunosuppression because of GVHD. Neither of our patients had any evidence of hemorrhagic cystitis. We present definitive renal pathology and detailed chronological evidence of the rising serum creatinine with simultaneous serum and urine BK PCR titers. In one of our cases, antiviral therapy did not seem beneficial as documented by continued renal dysfunction and elevated serum/urine BK PCR titers. Based on our report, intense immunosuppression in pediatric HCT recipients seems to be involved in the activation of BK virus and BK nephropathy should be suspected even in the absence of hematuria in HCT recipients with unexplained renal dysfunction.

Adenovirus infection and treatment with cidofovir in children after liver transplantation

In a retrospective study, serum samples from 21 pediatric liver transplant recipients were analysed by quantitative real-time PCR for ADV infection up to 24 wk after Tx. ADV DNA was detected in serum of eight children after Tx, one of whom developed life-threatening fulminant hepatitis and sepsis. None of these children were symptomatic at the time of first detection of ADV DNA in serum after Tx. Seven children with positive ADV PCR had low adenoviral loads, showed no increase in viral load and remained clinically asymptomatic in the follow-up period of 24 wk. After 10 wk under immunosuppression one child presented clinically with adenoviral sepsis and severe necrotizing hepatitis. This patient revealed a dramatic increase of ADV from baseline titers up to 1.3 x 10(9 )copies/mL serum within 10 wk after Tx. ADV was also detected in a liver biopsy of this child at 1.2 x 10(4) copies/cell and typed by sequence analysis as human ADV species C, type 6, a rarely detected ADV type and first described in a liver transplant patient. Immunosuppression was reduced in this patient immediately and the antiviral drug cidofovir administered intravenously followed by viral suppression and clinical improvement of the child.

Safety and tolerability of cidofovir in high-risk pediatric patients

Adenovirus (ADV) infection is a serious complication after hematopoietic stem cell transplantation with significant morbidity and mortality. Cidofovir has emerged as the primary therapy for ADV infection, but its use has been limited by concerns of nephrotoxicity. We report the safety and tolerability of 234 cidofovir infusions in 23 patients at a single institution, and demonstrate evidence of acceptable nephrotoxicity despite concomitant use of other nephrotoxic agents. Three patients suffered adverse events, two related to the hydration regimen associated with cidofovir administration. We conclude that cidofovir is a safe and mostly well tolerated drug in a high-risk pediatric population.

Viruses and kidney disease: beyond HIV

SUMMARY

Human immunodeficiency virus (HIV)-infected patients may acquire new viral co-infections; they also may experience the reactivation or worsening of existing viral infections, including active, smoldering, or latent infections. HIV-infected patients may be predisposed to these viral infections owing to immunodeficiency or risk factors common to HIV and other viruses. A number of these affect the kidney, either by direct infection or by deposition of immune complexes. In this review we discuss the renal manifestations and treatment of hepatitis C virus, BK virus, adenovirus, cytomegalovirus, and parvovirus B19 in patients with HIV disease. We also discuss an approach to the identification of new viral renal pathogens, using a viral gene chip to identify viral DNA or RNA.

Viral lower urinary tract infections

Lower urinary tract infections (UTIs) are common among the general population and are most often caused by bacterial pathogens. Viruses are an uncommon cause of UTIs in an immunocompetent host; however, viruses are increasingly recognized as the cause of lower UTI, especially hemorrhagic cystitis, among immunocompromised patients. BK virus, adenovirus, and cytomegalovirus are predominant pathogens involved in hemorrhagic cystitis after stem cell and solid organ transplantation, and their early diagnosis and treatment may prevent significant morbidity of hemorrhagic cystitis. The diagnosis of viral lower UTI is based on molecular techniques, and real-time polymerase chain reaction is often the method of choice because it allows for quantification of viral load. Cidofovir is becoming a drug of choice in viral UTIs because it is active against the most common viral pathogens. This review discusses the epidemiology, pitfalls in diagnosis, and current treatment of viral UTIs.

Treatment of adenovirus pneumonia with cidofovir in pediatric lung transplant recipients

BACKGROUND

Adenovirus pneumonia results in significant morbidity and mortality in lung transplant recipients. Cidofovir allows for directed therapy but can result in nephrotoxicity. We report our experience with cidofovir for the treatment of adenovirus pneumonia in pediatric lung transplant recipients.

METHODS

In a retrospective review, we identified four cases of culture-proven adenovirus pneumonia in children who underwent lung transplantation at Texas Children's Hospital (TCH). All patients received cidofovir 1 mg/kg every other day or three times a week for a total of 4 weeks. Probenecid and intravenous hydration were administered in conjunction with the cidofovir. Intravenous immunoglobulin (IVIg) was given as adjunctive therapy, and immunosuppression was not modified during the treatment course.

RESULTS

The four cases of adenovirus pneumonia comprised 4 of the 54 (7%) lung transplantations performed at TCH from 2002 to 2006, and all were in children <3 years of age. All patients developed pneumonia within 2 months after transplantation. With cidofovir treatment, three of the four children survived. Among the survivors, two developed early bronchiolitis obliterans within 1 year after transplant, and one has continued to have good graft function at 2 years after transplant. All patients maintained normal renal function throughout the treatment course.

CONCLUSIONS

Pediatric lung transplant recipients <3 years of age are at increased risk of adenovirus pneumonia early after transplantation. Cidofovir, when used in the modified dosing regimen and in combination with IVIg and renal protection measures, is a safe and potentially effective treatment option for adenovirus pneumonia in lung transplant recipients.

Quantification of adenovirus species B and C viremia by real-time PCR in adults and children undergoing stem cell transplantation

Adenovirus infection during stem cell transplantation is associated with high morbidity and mortality. Adenovirus species B and C have been the main causes for these infections; however, epidemiological details about the species are still unclear. To clarify the contributions of species B and C adenovirus, the DNA was tested serially by quantitative real-time PCR in peripheral blood, stool and urine of 32 patients (16 adults and 16 children) undergoing stem cell transplantation. Adenovirus species B viremia was detected in 10 of 16 adult and 6 of 16 pediatric transplant recipients. Adenovirus species C viremia was also detected simultaneously in five adult and three pediatric recipients. The stool and urine of patients with adenovirus viremia were also positive for the same adenovirus species as in blood. In contrast, in none of 50 healthy adult controls was adenovirus species B or C viremia detected. Among patients who developed adenovirus viremia, one adult recipient developed disseminated disease and died from multiple organ failure. The remaining patients experienced fever of several degrees and/or diarrhea during the period of adenovirus viremia; however, they all recovered without antiviral therapy. The results indicated that stem cell transplantation was frequently associated with adenovirus species B or C viremia, although it did not always cause serious infectious complications.

BK virus infection after non-renal transplantation

Infection with BK virus (BKV), a member of the Polyomavirus (PV) family, is ubiquitous, with the virus remaining in a latent form in the kidney and urinary tract. This infection is usually asymptomatic, but with impairment of the cellular immune system the virus can reactivate and lead to tissue damage. In recipients of bone marrow and solid organ transplants, PV reactivation can be associated with disease in urinary tract and kidneys. BKV was first discovered in 1971 from the urine of a kidney transplant recipient who had developed ureteral stenosis 4 months after transplantation. While much of the subsequent research focuses on patients after renal transplantation, we will review PV impact in patients after bone marrow transplant (BMT) and those with non-renal solid organ transplants.

Low-dose cidofovir treatment of BK virus-associated hemorrhagic cystitis in recipients of hematopoietic stem cell transplant

In recipients of hematopoietic stem cell transplants (HSCTs), BK virus (BKV) has been associated with late-onset hemorrhagic cystitis (HC). In our institution, HSCT recipients with BKV-associated HC are treated with 1 mg/kg of cidofovir weekly. We identified HSCT recipients with BKV-associated HC, treated with weekly cidofovir. Microbiological response was defined as at least a one log reduction in urinary BKV viral load; clinical response was defined as improvement in symptoms and stability or reduction in the grade of cystitis. Nineteen allogeneic HSCT patients received a mean of 4.5 weekly doses of cidofovir. HC occurred at a mean of 68.7 days after transplant. A clinical response was detected in 16/19 (84%) patients, and 9/19 (47%) had a measurable microbiological response (8/10 nonresponders had a BKV viral load above the upper limit of the assay before treatment). Fourteen out of nineteen (74%) patients had no significant increase in serum creatinine. Five patients with renal dysfunction resolved after completion of the therapy and removal of other nephrotoxic agents. We conclude that weekly low-dose cidofovir appears to be a safe treatment option for BKV-associated HC. Although the efficacy of low-dose cidofovir is not proven, a prospective trial is warranted.

Local administration of cidofovir for human papilloma virus associated skin lesions in transplant recipients

Human papilloma virus (HPV)-associated diseases are increasingly diagnosed in solid organ recipients. Cidofovir (CDV) is a broad-spectrum antiviral agent with activity against all human herpes viruses and HPV. From 2000-2004, a total of 1303 solid organ transplants (SOT) were performed at our center. Six transplant recipients were treated with topical CDV for HPV-associated lesions. One cardiac recipient responded to a single injection of CDV into his recurrent anal condylomata. In a renal recipient with recurrent penile condylomata CDV was injected into the lesions four times (2 week interval) until lesions regressed. One renal recipient developed multiple vaginal and anal intradermal neoplasias, which relapsed after laser ablation. The lesions were repeatedly injected with CDV and completely disappeared. Two renal recipients with widespread verrucae vulgares were treated with CDV gel, which resulted in regression of the lesions. One patient developed donor derived verrucae vulgares on both transplanted hands, which responded to CDV gel. Four of the six patients were switched from calcineurin inhibitors (CNIs) to Sirolimus (SIR). CDV was found effective in the treatment of HPV-associated skin lesions in SOT recipients. It needs to be determined whether switch from CNIs to SIR might have contributed to the beneficial effect of CDV.

Viral lower urinary tract infections

Lower urinary tract infections (UTIs) are common among the general population and are most often caused by bacterial pathogens. Viruses are an uncommon cause of UTIs in an immunocompetent host; however, viruses are increasingly recognized as the cause of lower UTI, especially hemorrhagic cystitis, among immunocompromised patients. BK virus, adenovirus, and cytomegalovirus are predominant pathogens involved in hemorrhagic cystitis after stem cell and solid organ transplantation, and their early diagnosis and treatment may prevent significant morbidity of hemorrhagic cystitis. The diagnosis of viral lower UTI is based on molecular techniques, and real-time polymerase chain reaction is often the method of choice because it allows for quantification of viral load. Cidofovir is becoming a drug of choice in viral UTIs because it is active against the most common viral pathogens. This review discusses the epidemiology, pitfalls in diagnosis, and current treatment of viral UTIs.

Pharmacotherapeutic options for the management of human polyomaviruses

Polyomaviruses [BK virus (BKV), JC virus (JCV) and simian virus 40 (SV40)] have been known to be associated with diseases in humans for over thirty years. BKV-associated nephropathy and JCV-induced progressive multifocal leukoencephalopathy (PML) were for many years rare diseases occurring only in patients with underlying severe impaired immunity. Over the past decade, the use of more potent immunosuppression (IS) in transplantation, and the Acquired Immune Deficiency Syndrome (AIDS) epidemic, have coincided with a significant increase in the prevalence of these viral complications. Prophylactic and therapeutic interventions for human polyomavirus diseases are limited by our current understanding of polyomaviral pathogenesis. Clinical trials are limited by small numbers of patients affected with clinically significant diseases, lack of defined risk factors and disease definitions, no proven effective treatment and the overall significant morbidity and mortality associated with these diseases. This chapter will focus on a review of the current and future research related to therapeutic targets and interventions for polyomavirus-associated diseases.

Adenovirus infections in transplant recipients

Adenoviruses are increasingly recognized as contributors to morbidity and mortality among stem cell and solid-organ transplant recipients. Clinical presentations range from asymptomatic viremia to respiratory and gastrointestinal disease, hemorrhagic cystitis, and severe disseminated illness. The limited clinical data available support the use of cidofovir for many of these illnesses. Prospective studies are needed to better understand the pathogenesis of and therapeutic options for adenoviral infections in this patient population.

Disseminated adenovirus infection with respiratory failure in pediatric liver transplant recipients: impact of intravenous cidofovir and inhaled nitric oxide

Adenoviruses (AdV) are opportunistic pathogens that can lead to severe infections and respiratory failure (acute respiratory distress syndrome, ARDS) with high mortality in immunosuppressed patients. Cidofovir (CDV) has been used in adenoviral disease in bone marrow transplant recipients. Two pediatric liver transplant recipients with disseminated adenoviral disease and ARDS were treated with reduction of immunosuppression, CDV, and inhaled nitric oxide (iNO). CDV 1 mg/kg was given three times per week intravenously with intravenous hydration and oral probenecid. Viral suppression and clinical improvement was achieved. AdV hepatitis did not occur, and graft function was preserved, although acute rejection occurred in both patients. Adverse effects were mild and transient not requiring dose modification. Severe hypoxemia was reversed with iNO 10-20 p.p.m. CDV treatment of AdV infections in organ transplant recipients and other immunocompromised patients should be further investigated in prospective studies.

Adenoviral disease in pediatric solid organ transplant recipients

Adenoviral disease in pediatric SOT recipients is emerging as an important viral pathogen, with serious consequences impacting morbidity, mortality and graft survival. The optimal diagnostic techniques, as well as therapy have yet to be established. This article reviews the current epidemiology of AdV in orthotopic liver, intestinal, cardiothoracic and renal transplant recipients. Issues related to diagnosis, notably the use of newer non-culture based viral detection methods and therapy, including anti-adenoviral agents and adoptive immunotherapy are discussed.

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.

Acyclic nucleoside phosphonates: a key class of antiviral drugs

Almost 20 years after the broad antiviral activity spectrum of the first acyclic nucleoside phosphonates was described, several of these compounds have become important therapies for DNA virus and retrovirus infections. Here, we review the discovery and development of acyclic nucleoside phosphonates, focusing on cidofovir and its potential in the treatment of various herpes-, papilloma-, polyoma-, adeno- and pox-virus infections, adefovir for the treatment of hepatitis B and tenofovir for the treatment of AIDS and the prevention of HIV infections.

Application of fibrin glue to damaged bladder mucosa in a case of BK viral hemorrhagic cystitis

BK virus is a common cause of severe hemorrhagic cystitis refractory to standard treatment. We describe a technique to achieve hemostasis after failed conservative therapy using fibrin glue applied suprapubically while visualizing and insufflating the bladder through a cystoscope. Long-term hemostasis was achieved using this novel procedure.

New agents for the prevention of opportunistic infections in haematopoietic stem cell transplant recipients

Over the past three decades, autologous and allogeneic haematopoietic stem cell transplants (HSCTs) have become effective treatments for a variety of malignant and nonmalignant conditions. Patients who undergo HSCT receive high doses of chemotherapy and/or radiation that induce a prolonged period of profound immunodeficiency, placing them at high risk for infection from a panoply of opportunistic organisms. Although supportive treatment for these patients has markedly improved, 10-20% of allogeneic HSCT recipients will ultimately succumb to infection. Joint guidelines to prevent opportunistic infection were released in 2000 by the Centers for Disease Control, the Infectious Diseases Society of America, and the American Society of Blood and Marrow Transplantation; however, treatment decisions for these patients are often based on limited studies or depend on institution-specific transplant protocols and antibiotic resistance patterns. This paper will discuss new agents for preventing bacterial, fungal and viral infections in HSCT recipients.

Prospects for adenovirus antivirals

Adenoviruses cause a number of self-limiting but often highly infectious diseases that affect multiple organs, most commonly those associated with respiratory, genitourinary and gastrointestinal tracts and the ocular surface. Many factors have driven a search for effective topical and systemic antivirals to adenoviruses. These include patient morbidity, economic losses and chronic visual disturbances associated with epidemic keratoconjunctivitis; and the startling recent trend of high morbidity and rising mortality associated with systemic adenoviral infections in the immunosuppressed, particularly paediatric bone marrow transplant recipients. The development of effective antivirals has proven to be a complex task, owing to the fact that multiple and often genetically divergent adenovirus serotypes can cause similar diseases. Currently, there remains no licensed systemic or topical treatment in the USA or Europe. However, many compounds have been explored for activity against adenoviruses, and some have been evaluated clinically in either a topical setting for ocular disease or in the setting of systemic treatment in the face of life-threatening adenovirus infections. This article outlines such compounds, discusses the potential for their clinical development, and highlights some problems that may be faced in evaluating their efficacy clinically.

Intravesical Instillation of Cidofovir in the Treatment of Hemorrhagic Cystitis Caused by Adenovirus Type 11 in a Bone Marrow Transplant Recipient

Hemorrhagic cystitis that occurs late after bone marrow transplantation (BMT) in BMT recipients is often associated with adenovirus or polyomavirus BK infections. Intravesical instillation of cidofovir in a BMT recipient with intractable hemorrhagic cystitis resulted in clinical improvement. Local cidofovir therapy for viral hemorrhagic cystitis could be an alternative to intravenous administration of cidofovir.

Monitoring of adenovirus infection in pediatric transplant recipients by quantitative PCR: report of six cases and review of the literature

Adenoviral (AdV) infections after transplantation remain a challenge in pediatric patients. Qualitative and quantitative PCR offer new approaches to early diagnosis and monitoring. However, their role in the management of AdV infections in pediatric transplant recipients remains to be determined. We report six children with positive qualitative serum-PCR for AdV on routine follow-up after transplantation (liver n = 4, hematopoetic stem cells (HSCT) n = 1, combined liver and HSCT n = 1). None of these children were symptomatic at the time of first detection of AdV. Two patients remained asymptomatic, one developed hemorrhagic cystitis and enteritis. Three children with positive PCR developed high viral load on quantitative PCR, all developed clinical AdV sepsis with further rising virus load. Despite antiviral therapy with cidofovir, these three patients died of septic multiorgan failure. Positive qualitative AdV-PCR from blood after pediatric transplantation is not necessarily followed by clinical disease. In case of positive AdV-PCR, monitoring by serial quantitative PCR is useful regarding treatment decision and prevention of fatal disease.

Smallpox: the basics

Variola major is the causative agent of smallpox, a severe disease that was arguably one of the most serious human pathogens in recorded history. Humans are the only known reservoir of variola major; no known animal or insect reservoirs have been identified. Thus, after eradication of smallpox through a global immunization effort, this incredibly lethal scourge was eliminated from all corners of the globe. Despite the total eradication of naturally occurring smallpox, there are still stockpiles of smallpox virus maintained in the United States and the former Soviet Union. Unfortunately, it is impossible to know if all smallpox stocks have been accounted for or whether unknown or unreported stocks of smallpox may still exist. In the age of genetic engineering, these viruses could theoretically be modified to increase their virulence to the levels associated with smallpox itself.