BK virus as the cause of meningoencephalitis, retinitis and nephritis in a patient with AIDS

Impact of a polyomavirus (BKV) infection on mRNA expression in human endothelial cells

Polyomavirus BK-associated nephropathy (PVAN) is an emerging cause of early renal transplant failure. In order to learn more about the cellular response to BK virus, microarrays were used to study its effect on mRNA expression in human endothelial cells. The oligo-based, 35k arrays used cover the predicted 25,000 human protein-expressing genes, and distinguish between a number of alternatively spliced mRNAs. Four parallel experiments were performed for each of two time-points (24 and 40 h) during the first round of the 48 h viral replicative cycle. Immunoperoxidase staining demonstrated that the pulse exposure to virus caused infection in at least 75% of the cells. At 24 h, 55 genes were more than doubly up-regulated and 249 genes were similarly down-regulated; at 40 h, the numbers were 242 and 104, respectively. Gene ontology analyses suggested that immune/defence response genes were selectively down-regulated. Genes involved in cell division and DNA replication tended to be up-regulated, which may reflect an attempt on behalf of the virus to promote viral replication. Genes associated with PVAN were not induced, suggesting that these genes are not required for viral replication, but rather reflect circumstances specific for the disease. Only a few immuno-related genes were turned on, including the interferon response genes G1P2 and IFIT3. However, some of the up-regulated genes of unknown function may be involved in viral defence.

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.

Reciprocal transactivation between HIV-1 and other human viruses

A variety of rare clinical syndromes are seen with strikingly increased prevalence in HIV-1-infected individuals, many with underlying viral etiologies. The emergence of these diseases in AIDS reflects a reduction in the ability of the immune system to mount an adequate defense against viruses in general due to the damage inflicted to the immune system by HIV-1 infection. However, in many cases, it has been found that HIV-1 can enhance the level of expression and hence the life cycle of other viruses independently of immunosuppression through specific interactions with the viruses. This can occur either directly by HIV-1 proteins such as Tat enhancing the activity of heterologous viral promoters, and/or indirectly by HIV-1 inducing the expression of cytokines and activation of their downstream signaling that eventually promotes the multiplication of the other virus. In a reciprocal manner, the effects of other viruses can enhance the pathogenicity of HIV-1 infection in individuals with AIDS through stimulation of the HIV-1 promoter activity and genome expression. The purpose of this review is to examine the cross-interactions between these viruses and HIV-1.

Quantitative real-time PCR assay for detection of human polyomavirus infection

The human polyomaviruses BK (BKV) and JC (JCV) affect immunosuppressed patients and are associated with urogenital tract (BKV) and CNS disorders (JCV) and in humans, the pathogenic role of the rhesus monkey virus, Simian virus 40 (SV40), is uncertain. These three viruses have somewhat overlapping tissue pathogenicity and detection of all three polyomaviruses is desirable. A broadly targeted, simple, single tube real-time degenerated quantitative PCR (QPCR) technique for detection of JCV, BKV and SV40 DNA was developed. To avoid false positive results, due to contamination with commonly used SV40 T-antigen plasmids, a conserved region of the VP2 gene was targeted. Down to 1-10 copies of target DNA per PCR reaction were detected. The QPCR was compared with a nested PCR on 41 clinical samples (urine, serum and plasma): 24 (58.5%) tested positive by nested PCR, whereas 31 (75.6%) were positive with QPCR. One CSF sample, from a patient with progressive multifocal leukoencephalopathy, was negative with the nested PCR but determined as positive by QPCR. Sera from 24 blood donors were negative with QPCR. The QPCR described had a high sensitivity. Its specificity was confirmed sequencing. The QPCR is simple to perform and is valuable for diagnosis of polyomavirus infection.

Prevalence of BK virus subtype I in Germany

The primary infection with human polyomavirus BK (BKV) occurs in early childhood and leads to viral latency within the urogenital tract. Up to 90% of the adult population are seropositive. In immunosuppressed patients, the BKV may be reactivated resulting in typical disease patterns like hemorrhagic cystitis and tubulointerstitial nephritis. Based on serological and molecular methods, BKV isolates were classified into four subtypes previously. Sixty specimens obtained from German renal and bone marrow transplant recipients were analyzed to gain data on the prevalence of BKV subtypes in Germany. With 90.9%, BKV subtype I was found to be predominant in both patient groups. 6.1% of BKV strains were classified as subtype IV. This pattern of phylogenetic distribution is similar to that demonstrated previously in England, Tanzania, the United States and Japan. Remarkably, there was one German BKV virus with a sequence which clusters together with strain SB in subtype II. The BKV subtype I was found to consist of at least three subgroups designated as Ia, Ib, and Ic. While the majority of the German sequences represent subgroup Ic, most of the Japanese sequences are clearly distinct. These findings support the hypothesis of distinct geographical prevalence of BKV subgroups. For the genotyping region, a relationship of BKV subgroups to disease patterns like hemorrhagic cystitis or tubulointerstitial nephritis could not be demonstrated.

Real-time PCR in clinical microbiology: applications for routine laboratory testing

Real-time PCR has revolutionized the way clinical microbiology laboratories diagnose many human microbial infections. This testing method combines PCR chemistry with fluorescent probe detection of amplified product in the same reaction vessel. In general, both PCR and amplified product detection are completed in an hour or less, which is considerably faster than conventional PCR detection methods. Real-time PCR assays provide sensitivity and specificity equivalent to that of conventional PCR combined with Southern blot analysis, and since amplification and detection steps are performed in the same closed vessel, the risk of releasing amplified nucleic acids into the environment is negligible. The combination of excellent sensitivity and specificity, low contamination risk, and speed has made real-time PCR technology an appealing alternative to culture- or immunoassay-based testing methods for diagnosing many infectious diseases. This review focuses on the application of real-time PCR in the clinical microbiology laboratory.

Genotypes of JC virus, DNA of cytomegalovirus, and proviral DNA of human immunodeficiency virus in eyes of acquired immunodeficiency syndrome patients

JC virus (JCV) is a human polyomavirus that exists in at least eight different genotypes as a result of coevolution with different human populations all over the world. Well adapted to its host, it usually persists in the kidneys and possibly the brain. If the host becomes immunodeficient, JCV can cause the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML). There is increasing evidence that JCV is transactivated by cytomegalovirus (CMV) and the human immunodeficiency virus (HIV). Both CMV and HIV can infect the retina of acquired immunodeficiency syndrome (AIDS) patients, causing severe necrosis in the case of CMV retinitis or a mild HIV-associated vasculopathy, with bleeding and cotton wool spots. The authors therefore investigated by polymerase chain reaction (PCR) whether DNA of these three viruses was detectable in paraffin-embedded eyes of AIDS patients with a clinical history of CMV retinitis. From a total of 65 eyes, JCV was detected in 21 (32%). Thirty-six (55%) were positive for CMV and 6 (9%) for proviral DNA of HIV. JCV and CMV were found in 13 eyes, JCV and HIV in 3 eyes, CMV and HIV in 1 eye, and DNA from all three viruses in 1 eye. The JCV genotypes were types 1A, 2A, 2E, 3, and 4. In 21 eyes of patients without AIDS, only one sample was JCV positive. In conclusion, JCV DNA can be detected in ocular tissue of AIDS patients at a significantly higher level than in eyes of nonimmunosuppressed patients. Further investigations will help to decide if JCV contributes to the retinopathy caused by CMV and HIV.

Polymorphism in the genome of non-passaged human polyomavirus BK: implications for cell tropism and the pathological role of the virus

Worldwide studies have demonstrated that the human polyomavirus BK resides ubiquitously in the human population. After primary infection, which occurs mainly during childhood, the virus seems to establish a life-long harmless infection in the host. However, impaired immune functions may lead to reactivation of BK virus. The recent findings that associate BK virus with an increasing number of clinical conditions, including renal, pulmonary, ophthalmologic, hepatic, neurological, and autoimmune diseases, has resuscitated the interest in this virus as a pathogenic agent. This review focuses on polymorphisms in the genomes of non-passaged BK virus isolates from nonneoplastic tissues, with special focus on the transcriptional control region, the regulatory proteins large T-antigen and agnoprotein, and the major capsid protein VP1. The possible implications of genome diversity with respect to cell tropism, pathogenicity, and therapeutic strategies are discussed.

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.

Specific delineation of BK polyomavirus in kidney tissue with a digoxigenin-labeled DNA probe

The detection of BK polyomavirus (BK virus, BKV) in kidney tissue is hampered by nonspecificity of antibodies suited to immunohistochemistry, and nonspecific background with in situ hybridization. The biotin-labeled DNA probe that is commercially available (Enzo Life Sciences, Inc.) shows good signal, but the intrinsic background in kidney tissue is high. We determined that the intrinsic background is due to endogenous biotin or biotin-binding activity in the renal tubular epithelium. Neither antibody blocking procedures nor an avidin/biotin block were entirely satisfactory for eliminating this background staining. We developed a digoxigenin-labeled DNA probe, and protocol, for detecting BK virus in formalin-fixed, paraffin embedded, kidney tissue obtained at autopsy. The hybridization signal is strong and there is no perceptible background staining. Eleven negative control kidneys all failed to hybridize. Conditions for low stringency hybridization may be employed, detecting both the related JC polyomavirus and BKV. Alternatively, high stringency hybridization conditions may be utilized, detecting BKV only. BK associated tubular necrosis is clearly demonstrated in two cases of BK nephritis.

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.

Oncogenic transformation by BK virus and association with human tumors

BK virus (BKV), a human polyomavirus closely related to JC virus and Simian Virus 40, is ubiquitous in human populations worldwide. After primary infection, BKV establishes a lifelong latent infection in many organs. BKV transforms rodent cells to the neoplastic phenotype and is highly oncogenic in rodents. This review considers the oncogenic potential of BKV in humans and its possible involvement in human tumors. BKV sequences and T antigen (Tag) are detected in several types of human neoplasms, although the viral load is generally low, with less than one copy of the viral genome per cell. The possible causative role of BKV in human oncogenesis rests on the ability of BKV Tag to inactivate the functions of tumor suppressor proteins p53 and pRB family as well as on its ability to induce chromosomal aberrations in human cells. A 'hit and run' mechanism and secretion of paracrine growth factors by BKV Tag-positive cells, recruiting into proliferation neighboring and distant cells, are discussed as possible BKV pathogenic elements in human oncogenesis.

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.

Molecular analysis of cerebrospinal fluid in viral diseases of the central nervous system

The use of nucleic acid (NA) amplification techniques has transformed the diagnosis of viral infections of the central nervous system (CNS). Because of their enhanced sensitivity, these methods enable detection of even low amounts of viral genomes in cerebrospinal fluid. Following more than 10 years of experience, the polymerase chain reaction or other NA-based amplification techniques are nowadays performed in most diagnostic laboratories and have become the test of choice for the diagnosis of several viral CNS infections, such as herpes encephalitis, enterovirus meningitis and other viral infections occurring in human immunodeficiency virus-infected persons. Furthermore, they have been useful to establish a viral etiology in neurological syndromes of dubious origin and to recognise unusual or poorly characterised CNS diseases. Quantitative methods have provided a valuable additional tool for clinical management of these diseases, whereas post-amplification techniques have enabled precise genome characterisation. Current efforts are aiming at further improvement of the diagnostic efficiency of molecular techniques, their speed and standardisation, and to reduce the costs. The most relevant NA amplification strategies and clinical applications of to date will be the object of this review.

BK virus-associated hemorrhagic cystitis in a Human Immunodeficiency Virus-infected patient

BK virus-associated hemorrhagic cystitis is a common clinical problem in bone marrow transplant recipients but is considered rare in other immunosuppressed patient populations. We describe a human immunodeficiency virus-infected patient with non-Hodgkin's lymphoma in whom BK virus-associated hemorrhagic cystitis developed; viruria was quantitated in urine by immunocytochemistry, and the patient showed no response to cidofovir.

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.

[Hemorrhagic cystitis caused by BK and JC polyomavirus in patients treated with bone marrow transplantation: clinical features and urologic management]

INTRODUCTION

Differential diagnosis of hematuria after bone marrow transplantation (B.M.T.) may include polyomavirus (BK and JC)-associated haemorrhagic cystitis. Many reports have implied BK virus as the major pathogen in the development of hemorrhagic cystitis after BMT. BK viruria is also associated with ureteric stenosis in renal allografts recipients. Viral urinary tract infections are uncommon in healthy individuals, but we can find them frequently in patients under immunosuppressive conditions.

MATERIAL AND METHODS

Retrospective study of 123 consecutive B.M.T. recipients in the period from 1995 to 2000, evaluating those with polyomavirus-associated hemorrhagic cystitis. We present patient's characteristics, primary disease, clinical features, diagnosis aspects and treatment of these "hidden hosts of urinary tract".

RESULTS

7 patients (5.7% of B.M.T.) developed BK or JC virus-associated hemorrhagic cystitis; 3 men and 4 women; median patient age was 29 years (range 14 to 45 years). Bacterial, mycobacterial and parasitic urine cultivates had negative results in all of them. The clinical course was characterized by a late onset of haemorrhagic cystitis (days +30 to +132 after BMT). All 7 patients developed macroscopic haematuria (duration 3 to 30 days). In 6 cases Graft Versus Host Disease (G.V.H.D.) criteria were found. Ultrasonographic studies revealed diffuse thickening of bladder wall in 5 patients. Hematuria was managed by hyperhydratation, blood transfusions, transurethral catheter and evacuation of blood clots, continuous bladder irrigation, urine alkalinization and antiviral therapy. No other more aggressive measures were required to stop the bleeding. Only 1 case of transient elevated creatinine.

CONCLUSIONS

Polyomavirus-associated haemorrhagic cystitis must be considered in differential diagnosis of hematuria in bone marrow transplantation recipients. Urological management, according with the severity and duration of hematuria, is frequently required.

Polyomavirus BK nephropathy: a (re-)emerging complication in renal transplantation

Persisting polyomavirus replication is now widely recognized as a (re-)emerging cause of renal allograft dysfunction. Up to 5% of renal allograft recipients can be affected about 40weeks (range 6-150) post-transplantation. Progression to irreversible failure of the allograft has been observed in up to 45% of all cases. The BK virus strain is involved in the majority of the cases. Risk factors may include treatment of rejection episodes and increasing viral replication under potent immunosuppressive drugs such as tacrolimus, sirolimus or mycophenolate. The diagnosis requires the histological demonstration of nuclear polyomavirus inclusions in affected tubular epithelial cells. Interstitial inflammatory infiltrates and fibrosis become more prominent in the persisting disease and may be difficult to distinguish from (coexisting) rejection. Detection of polyomavirus-inclusion bearing cells ('decoy cells') in the urine and quantification of BK virus DNA in the plasma have been proposed as surrogate markers for polyomavirus replication and allograft disease, respectively. Antiviral treatment is not yet established; however, reports of treatment with cidofovir are encouraging. Current management aims at the judicious modification and/or reduction of immunosuppression which, in view of preceding or concurrent rejection, is not without risk.

Bk virus: a clinical review

We present a review of the clinically oriented literature about BK virus, a relative of JC virus, which is the etiologic agent of progressive multifocal leukoencephalopathy (PML). The kidney, lung, eye, liver, and brain have been proposed as sites of BK virus-associated disease, both primary and reactivated. BK virus has also been detected in tissue specimens from a variety of neoplasms. We believe that BK virus is most often permissively present in sites of disease in immunosuppressed patients, rather than being an etiologic agent that causes symptoms or pathologic findings. There is, however, strong evidence for BK virus-associated hemorrhagic cystitis and nephritis, especially in recipients of solid organ or bone marrow transplants. Now that BK virus can be identified by use of specific and sensitive techniques, careful evaluation of the clinical and pathologic presentations of patients with BK virus will allow us to form a clearer picture of viral-associated pathophysiology in many organ systems.