BK virus encephalitis in a patient with AIDS and lymphoma

AIDS-Associated BK Virus Nephropathy in Native Kidneys: A Case Report and Review of the Literature

BK virus (BKV) is a small DNA virus, a member of the polyomavirus family, that causes an opportunistic infection in immunocompromised patients, especially kidney transplant patients. This virus establishes a lifelong infection in most of the population, and once it reactivates in an immunocompromised state, leads to BKV nephropathy. This review seeks to assess the correlation between severe immunosuppression, evident by low CD4 cell counts in HIV-positive patients, and the reactivation of BKV, causing nephropathy. A literature review was conducted, extracting, and analyzing case reports of HIV-positive patients showing correlations between their degree of immunosuppression, as evidenced by their CD4 counts, and the degree of BKV infectivity, confirmed by kidney biopsy. A total of 12 cases of BKV nephropathy in HIV-infected patients were reviewed. A common finding was the presence of profound immunosuppression, with most patients having CD4 counts ≤50 cells/ mm3. A substantial number also had comorbid malignancies, with some undergoing chemotherapy, potentially increasing the risk of BKV reactivation. In addition to the HIV status and malignancies, other risk factors for BKV reactivation included older age, male gender, diabetes mellitus, Caucasian race, and ureteral stent placement. BKV nephropathy in HIV patients with native kidneys is closely correlated with severe immunosuppression. Although therapeutic strategies exist for post-transplant patients, aside from the treatment of HIV with highly active anti-retroviral therapy (HAART), which potentially helps with clearing BKV by increasing CD4 count, there is no definitive treatment for a native kidney BKV nephropathy in patients with AIDS. The complexity of the cases and severity of comorbidities indicate the need for further research to develop therapeutic strategies tailored to this population.

BK Polyomavirus Virus Glomerular Tropism: Implications for Virus Reactivation from Latency and Amplification during Immunosuppression

BK polyomavirus (BKPyV), or BKV infection, is ubiquitous and usually non-pathogenic, with subclinical infections in 80–90% of adults worldwide. BKV infection is often associated with pathology in immunocompromised individuals. BKV infection often is associated with renal impairment, including ureteral stenosis, hemorrhagic cystitis, and nephropathy. BKV infection is less commonly associated with pneumonitis, retinitis, liver disease, and meningoencephalitis. BKV is known to replicate, establish latency, undergo reactivation, and induce clinical pathology in renal tubular epithelial cells. However, recent in vitro studies support the notion that BKV has expanded tropism-targeting glomerular parenchymal cells of the human kidney, which could impact glomerular function, enhance inflammation, and serve as viral reservoirs for reactivation from latency during immunosuppression. The implications of BKV expanded tropism in the glomerulus, and how specific host and viral factors that would contribute to glomerular inflammation, cytolysis, and renal fibrosis are related to BKV associated nephropathy (BKVAN), have not been explored. The pathogenesis of BKV in human glomerular parenchymal cells is poorly understood. In this review, I examine target cell populations for BKV infectivity in the human glomerulus. Specifically, I explore the implications of BKV expanded tropism in the glomerulus with regard viral entry, replication, and dissemination via cell types exposed to BKV trafficking in glomerulus. I also describe cellular targets shown to be permissive in vitro and in vivo for BKV infection and lytic replication, the potential role that glomerular parenchymal cells play in BKV latency and/or reactivation after immunosuppression, and the rare occurrence of BKV pathology in glomerular parenchymal cells in patients with BKVAN.

BK Virus Replication in the Glomerular Vascular Unit: Implications for BK Virus Associated Nephropathy

BACKGROUND

BK polyomavirus (BKV) reactivates from latency after immunosuppression in renal transplant patients, resulting in BKV-associated nephropathy (BKVAN). BKVAN has emerged as an important cause of graft dysfunction and graft loss among transplant patients. BKV infection in kidney transplant patients has increased over recent decades which correlates with the use of more potent immunosuppressive therapies. BKV infection of the Glomerular Vascular Unit (GVU) consisting of podocytes, mesangial cells, and glomerular endothelial cells could lead to glomerular inflammation and contribute to renal fibrosis. The effects of BKV on GVU infectivity have not been reported.

METHODS

We infected GVU cells with the Dunlop strain of BKV. Viral infectivity was analyzed by microscopy, immunofluorescence, Western blot analysis, and quantitative RT-PCR (qRT-PCR). The expression of specific proinflammatory cytokines induced by BKV was analyzed by qRT-PCR.

RESULTS

BKV infection of podocytes, mesangial cells, and glomerular endothelial cells was confirmed by qRT-PCR and positive staining with antibodies to the BKV VP1 major capsid protein, or the SV40 Large T-Antigen. The increased transcriptional expression of interferon gamma-induced protein 10 (CXCL10/IP-10) and interferon beta (IFNβ) was detected in podocytes and mesangial cells at 96 h post-infection.

CONCLUSIONS

All cellular components of the GVU are permissive for BKV replication. Cytopathic effects induced by BKV in podocytes and glomerular endothelial cells and the expression of CXCL10 and IFNβ genes by podocytes and mesangial cells may together contribute to glomerular inflammation and cytopathology in BKVAN.

BK polyomavirus: a review of the virology, pathogenesis, clinical and laboratory features, and treatment

BK polyomavirus (BKPyV) is a non-enveloped, circular dsDNA virus with a genome of approximately 5100 base pairs. It can be divided into four major genotypes, but the effects of different genotypes on clinical disease are uncertain. Primary BKPyV infection is generally acquired asymptomatically in childhood. It establishes low-level persistence in many tissues, particularly the genitourinary tract. Reactivation can lead to severe disease including BKPyV-associated nephropathy confirmed by renal biopsy, hemorrhagic cystitis and meningoencephalitis. Nucleic acid amplification testing of blood and urine is the main diagnostic and prognostic test for BKPyV infection. The treatment of BKPyV infection has concentrated on reduction in immunosuppressive therapy. Recent studies suggest that antiviral drugs have demonstrated only modest benefit, but adoptive T-cell therapies offer potential advances.

BK Virus Encephalitis in HIV-Infected Patients: Case Report and Review

Encephalitis and meningitis due to BKPyV are unusual and emerging condition. Only a few cases of BKPyV encephalitis have been reported in hematopoietic stem cell transplant recipients, with the majority of cases presenting with concurrent hemorrhagic cystitis and HIV-infected patients. The authors report two HIV-infected patients with the diagnosis of BKPyV encephalitis and discuss the main clinical, diagnostic, and therapeutic aspects of this infection in patients with AIDS. Physicians should be aware to recognize the main clinical features and diagnose BKPyV central nervous infection in the setting of AIDS.

BK virus encephalopathy and sclerosing vasculopathy in a patient with hypohidrotic ectodermal dysplasia and immunodeficiency

Human BK polyomavirus (BKV) is reactivated under conditions of immunosuppression leading most commonly to nephropathy or cystitis; its tropism for the brain is rare and poorly understood. We present a unique case of BKV-associated encephalopathy in a man with hypohidrotic ectodermal dysplasia and immunodeficiency (HED-ID) due to IKK-gamma (NEMO) mutation, who developed progressive neurological symptoms. Brain biopsy demonstrated polyomavirus infection of gray and white matter, with predominant involvement of cortex and distinct neuronal tropism, in addition to limited demyelination and oligodendroglial inclusions. Immunohistochemistry demonstrated polyoma T-antigen in neurons and glia, but expression of VP1 capsid protein only in glia. PCR analysis on both brain biopsy tissue and cerebrospinal fluid detected high levels of BKV DNA. Sequencing studies further identified novel BKV variant and disclosed unique rearrangements in the noncoding control region of the viral DNA (BKVN NCCR). Neuropathological analysis also demonstrated an unusual form of obliterative fibrosing vasculopathy in the subcortical white matter with abnormal lysosomal accumulations, possibly related to the patient's underlying ectodermal dysplasia. Our report provides the first neuropathological description of HED-ID due to NEMO mutation, and expands the diversity of neurological presentations of BKV infection in brain, underscoring the importance of its consideration in immunodeficient patients with unexplained encephalopathy. We also document novel BKVN NCCR rearrangements that may be associated with the unique neuronal tropism in this patient.

BK virus encephalitis: case report, review of the literature, and description of a novel treatment modality

OBJECTIVE

To describe a case of BK virus encephalitis with attempted direct antiviral therapy, review the reported cases of BK virus in the central nervous system, and report the novel use of intravenous cimetidine in place of oral probenecid to minimize the toxicities of intravenous cidofovir.

CASE SUMMARY

A 36-year-old male with acute myelomonocytic leukemia and subsequent myelodysplastic syndrome underwent allogeneic hematopoietic stem cell transplant. His course was complicated by severe graft-versus-host disease involving his skin and gastrointestinal tract. Five weeks after transplantation, he developed fever and confusion. Magnetic resonance imaging was suggestive of limbic encephalitis and cerebrospinal fluid tested positive for BK virus. Therapy with intravenous cidofovir was thought to be indicated. Although probenecid is commonly used to minimize the toxicities of cidofovir, the patient's severe graft-versus-host disease raised concerns about absorption of oral medications. Based on animal models and pharmacokinetic data, intravenous cimetidine was used in place of oral probenecid. Despite these therapies, the patient's mental status did not improve. He developed progressive organ system failure, and care was ultimately withdrawn.

DISCUSSION

BK virus is increasingly described as a cause of encephalitis. The majority of reported cases have occurred in immunocompromised patients and have generally had a poor outcome. This case describes attempted antiviral therapy using cidofovir, the antiviral agent used most frequently in other syndromes due to BK virus. Intravenous cimetidine is a novel modality used to minimize ocular and renal toxicities frequently seen with cidofovir, and we believe this warrants further investigation.

CONCLUSIONS

BK virus may be a cause of encephalitis in immunocompromised hosts, and cidofovir represents a possible treatment option. Intravenous cimetidine can be considered to minimize toxicities associated with cidofovir use in patients unable to tolerate or absorb oral probenecid.

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.

The human polyomavirus BK (BKPyV): virological background and clinical implications

Polyomavirus BK (BKPyV) infects most people subclinically during childhood and establishes a lifelong infection in the renourinary tract. In most immunocompetent individuals, the infection is completely asymptomatic, despite frequent episodes of viral reactivation with shedding into the urine. In immunocompromised patients, reactivation followed by high-level viral replication can lead to severe disease: 1-10% of kidney transplant patients develop polyomavirus-associated nephropathy (PyVAN) and 5-15% of allogenic hematopoietic stem cell transplant patients develop polyomavirus-associated haemorrhagic cystitis (PyVHC). Other conditions such as ureteric stenosis, encephalitis, meningoencephalitis, pneumonia and vasculopathy have also been associated with BKPyV infection in immunocompromised individuals. Although BKPyV has been associated with cancer development, especially in the bladder, definitive evidence of a role in human malignancy is lacking. Diagnosis of PyVAN and PyVHC is mainly achieved by quantitative PCR of urine and plasma, but also by cytology, immunohistology and electron microscopy. Despite more than 40 years of research on BKPyV, there is still no effective antiviral therapy. The current treatment strategy for PyVAN is to allow reconstitution of immune function by reducing or changing the immunosuppressive medication. For PyVHC, treatment is purely supportive. Here, we present a summary of the accrued knowledge regarding BKPyV.

Fatal encephalitis due to BK virus in a patient with common variable immunodeficiency: a case report

Encephalitis due to BK virus is a rare condition. Here, we describe a young male patient with common variable immunodeficiency who developed fatal encephalitis due to BK virus. The patient presented initially with ocular symptoms that were followed by behavioral changes and spastic quadriparesis. Diagnosis was made by the compatible clinical findings and detection of viral DNA by polymerase chain reaction in the cerebrospinal fluid. To the best of our knowledge, this is the first report of BK virus encephalitis in a patient with common variable immunodeficiency. We suggest that BK virus should be suspected in cases of encephalitis; particularly in patients with immunodeficiency.

A child with BK virus infection: inadequacy of current therapeutic strategies

In this report, we describe the development of BKVN in the native kidneys of a child with a cardiac transplant. Elevated BK viral DNA load by PCR necessitated a prolonged course of treatment with escalating doses of cidofovir. Despite a reduction in plasma BK viral load, the infection evolved into an invasive CNS disease, resulting in rhomboencephalitis. This case highlights the need for awareness of the possibility of developing multiorgan complications from BKV infection. The current treatment options for BKV tissue invasive disease are inadequate and need to be improved.

BK polyomavirus with archetypal and rearranged non-coding control regions is present in cerebrospinal fluids from patients with neurological complications

BK polyomavirus (BKPyV) has recently been postulated as an emerging opportunistic pathogen of the human central nervous system (CNS), but it is not known whether specific strains are associated with the neurotropic character of BKPyV. The presence of BKPyV large T-antigen DNA was examined in 2406 cerebrospinal fluid (CSF) samples from neurological patients with suspected JC polyomavirus infection. Twenty patients had a large T-antigen DNA-positive specimen. The non-coding control region (NCCR) of the BKPyV strains amplified from CSF from these 20 patients, strains circulating in renal and bone marrow transplant recipients and from healthy pregnant women was sequenced. The archetypal conformation was the most prevalent in all groups and 14 of the neurological patients harboured archetypal strains, while the remaining six patients possessed BKPyV with rearranged NCCR similar to previously reported variants from non-neurological patients. Transfection studies in Vero cells revealed that five of six early and four of six late rearranged promoters of these CSF isolates showed significantly higher activity than the corresponding archetypal promoter. From seven of the neurological patients with BKPyV DNA-positive CSF, paired serum samples were available. Five of them were negative for BKPyV DNA, while serum from the remaining two patients harboured BKPyV strains with archetypal NCCR that differed from those present in their CSF. Our results suggest that NCCR rearrangements are not a hallmark for BKPyV neurotropism and the dissemination of a rearranged NCCR from the blood may not be the origin of BKPyV CNS infection.

Human Polyomavirus-Associated Cerebral Disorders in the Post-HAART Era

Human polyomavirus JC is the causative agent of a deadly form of sudden onset dementia, progressive multifocal leukocoencephalopathy (PML). PML is highly prevalent in immunodeficient populations, specially those undergoing chemotherapy, immunosuppressive treatments for autoimmune conditions, and HIV-1/AIDS patients. In fact, before the highly active antiretroviral therapy (HAART) regimens became available, PML was a leading cause of death in HIV-1 seropositive individuals. However, patients under HAART show increased survival times with better prognoses. In this report we described the main differences between PML before and after the HAART era; highlighting the new patterns of presentation, the neurotropism of other human polyomaviruses, and the increased prevalence of immune reconstitution inflammatory syndrome (IRIS), as a complication of PML in patients under HAART. Lastly, we propose a revised classification of human poliomavirus-associated cerebral disorders that may reflect more accurately what clinicians encounter in their everyday practice.

Hemorrhagic cystitis and possible neurologic disease from BK virus infection in a patient with AIDS

BK virus (BKV)-associated hemorrhagic cystitis occurs in bone marrow transplant recipients but is rare among other immunosuppressed patients. We present a rare case of BKV-associated hemorrhagic cystitis in a 48-year-old man with AIDS and previously diagnosed progressive multifocal leukoencephalopathy.

Productive simian virus 40 infection of neurons in immunosuppressed Rhesus monkeys

There currently is no animal model of JC virus-associated progressive multifocal leukoencephalopathy (PML). Reactivation of simian virus 40 (SV40) in immunosuppressed rhesus monkeys, however, rarely causes a PML-like illness. We sought to isolate a neurotropic clone of SV40 and determine its pathogenic potential in monkeys. The clone SV40CNS1 was amplified by polymerase chain reaction from the brain DNA of a simian/human immunodeficiency virus-infected monkey that had developed PML and meningoencephalitis. Compared with the SV40 prototype 776, SV40CNS1 had a small number of single-amino-acid mutations and caused a productive infection in monkey fibroblasts. It was inoculated into 2 SV40-negative, simian/human immunodeficiency virus-immunosuppressed monkeys. Both animals developed meningoencephalitis with productive SV40 infection of cerebral cortical neurons and glia in the superficial layers of the cortex and at the gray-white junction. Focal SV40-infected cells were also found in the cerebellar molecular and granule cell layers and white matter. Both animals also developed disseminated SV40 infection with nephritis and pneumonitis. Thus, SV40CNS1 is infectious and pathogenic in immunosuppressed monkeys, but it induces encephalitis with fulminant productive infection in cortical neurons and systemic disease, rather than PML. These findings shed new light on SV40 neurotropism and expand the host cell range of this virus.

Rapidly progressive dementia

In contrast with more common dementing conditions that typically develop over years, rapidly progressive dementias can develop subacutely over months, weeks, or even days and be quickly fatal. Because many rapidly progressive dementias are treatable, it is paramount to evaluate and diagnose these patients quickly. This review summarizes recent advances in the understanding of the major categories of RPD and outlines efficient approaches to the diagnosis of the various neurodegenerative, toxic-metabolic, infectious, autoimmune, neoplastic, and other conditions that may progress rapidly.

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.

BK virus associated meningoencephalitis in an AIDS patient treated with HAART

A severely immune-suppressed AIDS patient was suspected of suffering from BK virus (BKV) meningoencephalitis, after being studied for common causes of neurological complications of co-infectious origin. Polymerase chain reaction (PCR) and sequence analysis of cerebrospinal fluid and brain samples, confirmed the presence of BKV. His clinical condition improved along with the regression of brain lesions, after modifications on his antiretroviral regime. Five months after discharge, the patient was readmitted because of frequent headaches, and a marked inflammatory reaction was evidenced by a new magnetic resonance imaging (MRI). The symptoms paralleled a rising CD4+ lymphocyte count, and immune reconstitution syndrome was suspected. This is the first non-postmortem report of BKV meningoencephalitis in an AIDS patient, showing clinical and radiographic improvement solely under HAART.

Activation of early gene transcription in polyomavirus BK by human immunodeficiency virus type 1 Tat

Polyomavirus BK (BKV) is a serious problem for immunocompromised patients, where latent virus can enter into the lytic cycle causing cytolytic destruction of host cells. BKV infects >80% of the population worldwide during childhood and then remains in a latent state in the kidney. In the context of immunosuppression in kidney transplant patients, reactivation of the viral early promoter (BKV(E)) results in production of T antigen, enabling virus replication and transition from latency to the lytic phase, causing polyomavirus-associated nephropathy. Reactivation of BKV can also cause complications such as nephritis, atypical retinitis and haemorrhagic cystitis in AIDS patients. Here, the effects of human immunodeficiency virus type 1 (HIV-1) proteins Tat and Vpr on BKV transcription were investigated and it was demonstrated that Tat dramatically stimulated BKV(E). Site-directed mutagenesis analysis of potential Tat-responsive transcriptional motifs complemented by an electrophoretic mobility shift assay (EMSA) showed that Tat activated BKV(E) by inducing binding of the NF-kappaB p65 subunit to a kappaB motif near the 3' end of BKV(E). In addition, a sequence within the 5' UTR of BKV(E) transcripts (BKV(E)-TAR) was identified that is identical to the HIV-1 transactivation response (TAR) element. The BKV(E)-TAR sequence bound TAT in RNA EMSA assays and deletion of the BKV(E)-TAR sequence eliminated Tat transactivation of BKV(E) transcription. Thus, Tat positively affected BKV(E) transcription by a dual mechanism and this may be important in diseases involving BKV reactivation in AIDS patients.

Atteintes du système nerveux central et infection par le VIH-1

Central nervous system complications are common in HIV-1 infected patients and occur either as a result of concomitant immunosuppression (opportunistic infections, lymphoma and tumors), as a primary manifestation of HIV infection, or as an adverse effect of therapy (immune restoration and toxicity). These complications contribute largely to patient morbidity and mortality. In the era of highly active antiretroviral therapy (HAART) these disease states have changed in presentation, outcome and incidence. We review in detail the epidemiology, pathogenesis, clinical features, diagnosis, and management of these disorders.

Cooperative interaction of p65 and C/EBPbeta modulates transcription of BKV early promoter

Reactivation of the human polyomavirus BK (BKV) has emerged as an important cause of allograft rejection in renal transplant recipients. Expression of the viral early promoter that leads to production of T-antigen is the first event in viral lytic infection. In an effort to understand the mechanism involved in the activation of BKV early gene (BKV(E)) expression, we analyzed the promoter/enhancer region of the virus and identified binding motifs for the inducible transcription factors NF-kappaB and C/EBPbeta, which are in juxtaposition to each other downstream from the early gene transcription initiation site. Results from transfection studies demonstrate that overexpression of the p65 subunit of NF-kappaB, but not C/EBPbeta stimulates transcription of the BKV(E) promoter in CV-1 cells. Interestingly, low level expression of C/EBPbeta showed a synergistic effect on p65 activation of the BKV(E) promoter, suggesting a functional cooperativity between these two regulators upon viral gene transcription. Results from DNA-binding studies showed the ability of p65 and C/EBPbeta to bind independently with BKV DNA as removal of the binding site for p65 or C/EBPbeta had no significant effect on the interaction of p65 and C/EBPbeta with their motifs, respectively. Functional evaluation of the mutant promoter with no binding sites for either NF-kappaB or C/EBPbeta showed that the observed synergism requires the p65 but not the C/EBPbeta binding site, suggesting cross-talk between C/EBPbeta and p65 in this event. Results from the co-expression of p65 and C/EBPbeta showed no evidence for the formation of a DNA-protein complex containing both p65 and C/EBPbeta, although results from protein-protein interaction studies verified the ability of C/EBPbeta to interact with p65. A dominant-negative isoform of C/EBPbeta which contains the DNA binding but not activation domain of full-length C/EBPbeta cooperated with p65 in activating the BKV(E) promoter, suggesting a functional interaction between the b-ZIP domain of C/EBPbeta and NF-kappaB.

Leucoencéphalopathie multifocale progressive à BK virus chez un patient immunodéprimé par une corticothérapie

INTRODUCTION

BK virus has been described previously in renal transplant patients, but has also been reported in cases of progressive multifocal leukoencephalopathy.

METHOD

A case of progressive BK virus multifocal leukoencephalopathy induced by long-term corticosteroid therapy is reported.

RESULTS

In our case, BK virus was detected in cerebrospinal fluid by polymerase chain reaction (PCR). A detailed review of similar cases in the literature showed most of them occurred in AIDS patients, but four involved immunocompetent patients.

CONCLUSION

Though BK virus infection usually leads to urinary tract symptoms in immunologically suppressed patients, it is important to be aware of its neurological manifestations and to recognize BK infections that can occur in immunocompetent patients.

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.

Identification of a unique BK virus variant in the CNS of a patient with AIDS

Human polyomavirus BK (BKV; GenBank or EMBL or DDBJ accession no. NC001538) is often reactivated in immunosuppressed patients. Reactivation has been associated primarily with excretion of the virus in the urine, and there have been few reports of renal and/or neurological disease caused by BKV in patients with acquired immunodeficiency syndrome (AIDS). Polymerase chain reaction, Southern blotting, and sequencing were used to detect and identify the noncoding control region (NCCR) of BKV in different tissues in an AIDS patient with meningoencephalitis, retinitis, and nephritis. An undescribed reorganized NCCR variant of the virus, completely different from the variants detected in peripheral blood leukocytes (PBLs) and urine, was identified in the cerebrospinal fluid (CSF) and CNS tissues. These results suggest that rearrangements in the NCCR of the virus have resulted in a BKV variant, which is better adapted to the host cell machinery of the cells in CNS tissue. The rearranged variant (BKV CNS) might have been involved in the initiation and/or development of the pathological lesions observed in the CNS-related tissues of this patient.

The changing pattern of HIV neuropathology in the HAART era

Highly active antiretroviral treatment (HAART), which has been available for most AIDS patients in France since 1996, has resulted in a dramatic improvement of the progression of the disease. From the survey of our series of 343 brains with acquired immunodeficiency syndrome (AIDS) from patients who died between 1985 and 2002, we found both quantitative and qualitative changes in the pattern of human immunodeficiency virus (HIV) neuropathology. Quantitatively, despite a dramatic decrease in the number of autopsies, brain involvement remained a major cause of death. There was an overall decrease in incidence of cerebral toxoplasmosis, cytomegalovirus encephalitis (CMVE), and HIV encephalitis (HIVE), for which successful treatment is available. This contrasted with the unchanged incidence of progressive multifocal leukoencephalopathy (PML) and malignant non-Hodgkin lymphomas (MNHL). However, when looking closer at the 3 last years, the incidence of diseases affecting patients with severe immunodepression (CMVE, PML, and MNHL) decreased between 2000 and 2002, whereas infections occurring in patients with milder immunodeficiency, toxoplasmosis, varicella-zoster encephalitis (VZVE), or herpes simplex virus encephalitis (HSVE) became more frequent. In addition, we found uncommon types of brain infection such as BK virus encephalitis or general paresis. Finally, we described new variants of HIVE: severe leukoencephalopathy with intense perivascular macrophage and lymphocyte infiltration, possibly due to an exaggerated response from a newly reconstituted immune system, and chronic "burnt out" forms of HIVE as VZVE, toxoplasmosis, or PML, possibly associated with prolonged survival, in which neither inflammation nor organisms could be detected. These findings are compared with those reported in other neuropathological studies from different developed countries.

BK virus regulatory region rearrangements in brain and cerebrospinal fluid from a leukemia patient with tubulointerstitial nephritis and meningoencephalitis

BK virus (BKV) was recovered by polymerase chain reaction (PCR) from brain, kidney, lung, urine, and cerebrospinal fluid (CSF) of a fatal case of BKV tubulointerstitial nephritis with dissemination to lung and brain. Viral regulatory regions in PCR-amplified urine and the lung samples were identical to the archetypal structure, WWT. In the brain and CSF, a rearranged sequence predominated, however. A 94-bp deletion preceded a 71-bp tandem duplication because the same 94-bp segment was deleted from both copies. PCR-amplified regulatory region products were cloned and sequenced to define further the extent of the rearranged structures. Two kidney clones were archetypal, whereas two others were rearranged differently from the brain and from each other. In contrast to the brain clones, the kidney rearrangements seemed to involve deletion after duplication. Three of four brain clones sequenced were identical to the rearrangement found to dominate in the PCR product. A fourth clone showed two short deletions without any duplication. The four CSF clones all showed rearrangements identical to that which was amplified by PCR from CSF and brain. This represents the first molecular analysis of a BKV strain obtained from a central nervous system infection, and it reveals regulatory region rearrangements reminiscent of those described in JC virus from brains with progressive multifocal leukoencephalopathy. We suggest that the presence in the CSF of BKV with a dominant rearranged regulatory region may be useful in the diagnosis of BKV meningoencephalitis secondary to BKV nephritis.