Detection of CSF-specific oligoclonal antibodies to recombinant JC virus VP1 in patients with progressive multifocal leukoencephalopathy

The intrathecal synthesis of antibodies against recombinant VP1, the major structural protein of JC virus (JCV), was studied in 18 patients with progressive multifocal leukoencephalopathy (PML) and in 31 patients with various neurological disorders. Two methods were used, the calculation of an antibody specific index (ASI) on one hand and an antigen-driven immunoblotting for the detection of oligoclonal antibodies on the other. Most PML patients displayed an elevated (> 1.5) ASI (78%) and anti-VP1 oligoclonal antibodies restricted to the cerebrospinal fluid (55%). Only two other patients (one case each of multiple sclerosis and of neuroborreliosis) also showed an intrathecal synthesis of anti-VP1 oligoclonal antibodies, likely as a result of a 'polyspecific' reaction within the central nervous system.

The T/t common exon of simian virus 40, JC, and BK polyomavirus T antigens can functionally replace the J-domain of the Escherichia coli DnaJ molecular chaperone

The N-terminal 70 residue "J-domain" of the Escherichia coli DnaJ molecular chaperone is the defining and highly conserved feature of a large protein family. Based upon limited, yet significant, amino acid sequence homology to the J-domain, the DNA encoding the T/t common exon of the simian virus 40 (SV40), JC, or BK polyoma virus T antigen oncoproteins was used to construct J-domain replacement chimeras of the E. coli DnaJ chaperone. The virally encoded J-domains successfully substituted for the bacterial counterpart in vivo as shown by (i) complementation for viability at low and high temperature of a hypersensitive bacterial reporter strain, and (ii) the restoration of bacteriophage lambda plaque forming ability in the same strain. The amino acid change, H42Q, in the SV40 T/t and the JC virus T/t exon, which is positionally equivalent to the canonical dnaJ259 H33Q mutation within the E. coli J-domain, entirely abolished complementing activity. These results strongly suggest that the heretofore functionally undefined viral T/t common exon represents a bona fide J-domain that preserves critical features of the characteristic domain fold essential for J-domain interaction with the ATPase domain of the Hsp70 family. This finding has implications for the regulation of DNA tumor virus T antigens by molecular chaperones.

Efficient production of JC virus in SVG cells and the use of purified viral antigens for analysis of specific humoral and cellular immune response

A new in vitro system for the production of the human polyomavirus JC virus (JCV) was established to circumvent the need for virus growth in primary human fetal glial cells (PHFG). The permanent cell line SVG, transformed by an origin-defective mutant of Simian Virus 40 (SV40) was used to grow JCV. JCV-specific RNA could be detected at day 5 and viral antigen at day 6 post infection (p.i.). Virus production peaked at day 16. Virus could be purified by differential centrifugation. The purified fraction consisted mainly of mature particles but contained also pentamers of the major structural virus protein 1 (VP1). The VP1-pentamers could be purified to near homogeneity. The purified virus particles stimulated a specific T-cell proliferation of peripheral blood monocytes (PBMCs) of a patient with progressive multifocal leukoencephalopathy (PML) and of two healthy individuals. In addition, JCV-particles and VP1-pentamers reacted specifically in an ELISA with a series of five PML-patient sera and four sera of individuals not affected by PML. These results demonstrate that purified whole virus particles are suitable for the analysis of specific cellular and humoral immune responses to JCV.

High titers of antibodies to two human polyomaviruses, JCV and BKV, correlate with increased frequency of chromosomal damage in human lymphocytes

Associations of antibody titers to the JC and BK human polyoma viruses and the frequency of chromosome aberrations (CA) in human peripheral blood lymphocytes were studied. Study group consisted of 33 workers occupationally exposed to low doses of ionizing radiation and 11 control persons. There were no statistically significant differences in the JC and BK virus titer values between two groups of donors. It was found that JC and BK virus titers explained approximately 6% of total inter-individual variation in CA frequency. Such factors as alcohol abuse, age and, in this special group, exposure to ionizing radiation explained an additional 53% of the total variation in CA frequency. In six clean-up workers and one control, rogue cell (cells with multiple chromosome-type aberrations) were found. The incidence of rogue cells correlated significantly with JC and BK virus titers as well as a history of recent acute respiratory disease.

T antigen of human papovavirus JC stimulates transcription of the POU domain factor Tst-1/Oct6/SCIP

Human papovavirus JC exhibits a strong tropism for glial cells in vivo. To a large extent, this effect is due to the pronounced glia specificity of viral gene expression, which is mediated by the specific interaction of glial transcription factors such as Tst-1/Oct6/SCIP with viral promoter sequences. Here we show that, in return, expression of the glial transcription factor Tst-1/Oct6/SCIP can be strongly activated by T antigen, the early gene product of JC virus, in a dose-dependent manner. In transient transfection experiments, stimulation by T antigen was entirely dependent on a 335-bp segment of the Tst-1/Oct6/SCIP gene promoter that included the transcriptional start site. The same fragment was also bound by purified T antigen in immunoprecipitation assays due to the presence of three closely spaced and tandemly oriented GAGGC pentamers. However, when this array of pentamers was mutated so that binding of T antigen was strongly reduced, T-antigen-dependent transcriptional activation remained unaffected. Thus, similar to viral late gene expression, transcriptional stimulation of the Tst-1/Oct6/SCIP gene by T antigen was not dependent on binding to GAGGC pentamers present within the promoter. Nevertheless, our data provide strong support for a model in which JC virus influences gene expression of its host cell via its early gene product in a manner favourable for its own propagation.

Evidence that the soluble factors secreted by activated immune cells suppress replication of human neurotropic JC virus DNA in glial cells

Coordination of the immune response to viral infection and disease in the brain is believed to involve bidirectional interaction between the immune system and the central nervous system (CNS). Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the CNS that generally affects patients exhibiting an immunocompromised condition due to various illnesses. The human polyomavirus, JCV, which infects greater than 70% of the adult population is the etiological agent of this disease. Infection with JCV occurs during childhood and the virus remains in the latent state with no apparent clinical signals. However, under immunocompromised conditions, the virus enters the lytic cycle, and upon cytolytic destruction of glial cells, causes PML. To understand the molecular mechanism underlying immune regulation of JCV replication, we have developed a cell culture system and have investigated the effect of soluble factors from T-cell cultures on replication of JCV DNA in glial cells. Our data demonstrate that replication of JCV DNA in the presence of PMA-stimulated T-cell supernatant is substantially decreased in transfected glial cells. Heat-inactivation and size-fractionation studies revealed participation of a heat labile factor(s) which loses its maximum activity at 60 degrees and ranges between 30 and 100 kDa in size. The unfractionated T-cell supernatant and the fraction enriched in 30- to 100-kDa proteins reduced the level of viral DNA replication during the early phase of the lytic cycle. These observations suggest that regulatory factors which are secreted by immune cells may modulate the level of JCV DNA replication in glial cells. The importance of these observations in reactivation of JCV in immunocompromised individuals and development of PML is discussed.

p53 inhibits JC virus DNA replication in vivo and interacts with JC virus large T-antigen

The onset of DNA replication is an important step within the life cycle of the human neurotropic polyomavirus JC. In this report, evidence that both the human and the murine tumor suppressor protein p53 strongly inhibit JCV DNA replication in vivo is presented. This inhibition is dose-dependent and not a secondary effect of a decreased expression of JCV large T-antigen in response to p53. Using deletion mutants of murine p53 and tumor-derived point mutations of human p53, the basis of the suppression of JCV DNA replication by p53 was dissected. Deletion of either the amino- or the carboxy-terminal domain of murine p53 did not interfere with the repression of JCV DNA replication. However, deletion of the highly conserved central region of p53 abolished the inhibitory effect on replication. The tumor-derived human mutant p53(His273) inhibited JCV DNA replication significantly, whereas another tumorigenic mutant, p53(His175), had no inhibitory effect Concomitantly, a direct protein-protein interaction between p53 and JCV large T-antigen was lost in mutants which did not affect JCV DNA replication. These results strongly suggest that p53 inhibits JCV DNA replication by interacting with JCV large T-antigen.

Production of the antigen and the antibody of the JC virus major capsid protein VP1

The DNA of the major capsid protein VP1 of the human polyomavirus JC virus (JCV), Taiwan-3 strain, was generated from the urine of an autoimmune disease patient by polymerase chain reaction (PRC). The VP1 DNA was cloned into a prokaryotic expression vector, pGEX-4T-1, for expression in E. coli. The nucleotide sequences and the deduced amino acid sequences were determined and compared with the JC virus prototype, Mad-1. Thirty nucleotides were different between these two strains. Six of the altered nucleotides affected amino acid coding and ten of them caused changes in endonuclease recognition sites. The recombinant VPI protein was purified and used to raise monospecific antiserum in rabbit. Recombinant JCV VP1 protein and its monospecific antiserum are important clinical reagents and could possibly be developed as a subunit vaccine and as a serological diagnostic antigen in the future. In addition, the region between amino acid residues 40 and 80 of JCV VP1 is predicted to be an antigenic epitope on the basis of its hydropathy plot and comparison with the VP1 sequences of SV40 and BK virus.

Hypothesis: "Rogue cell"-type chromosomal damage in lymphocytes is associated with infection with the JC human polyoma virus and has implications for oncopenesis

The hemagglutination inhibition antibody titers against the JC and BK polyoma viruses (JCV and BKV, respectively) are significantly elevated in individuals exhibiting "rogue" cells among their cultured lymphocytes. However, the elevation is so much greater with respect to JCV that the BKV elevation could readily be explained by cross reactivity to the capsid protein of these two closely related viruses. The JCV exhibits high sequence homology with the simian papovavirus, simian virus 40 (SV40), and inoculation of human fetal brain cells with JCV produces polyploidy and chromosomal damage very similar to that produced by SV40. We suggest, by analogy with the effects of SV40, that these changes are due to the action of the viral large tumor antigen, a pluripotent DNA binding protein that acts in both transcription and replication. The implications of these findings for oncogenesis are briefly discussed.

Purified JC virus T antigen derived from insect cells preferentially interacts with binding site II of the viral core origin under replication conditions

The human polyomavirus JC virus (JCV) establishes persistent, asymptomatic infections in most individuals, but in severely immunocompromised hosts it may cause the fatal demyelinating brain disease progressive multifocal leukoencephalopathy. In cell culture JCV multiplies inefficiently and exhibits a narrow host range. This restricted behavior occurs, in part, at the level of DNA replication, which is regulated by JCV's multifunctional large tumor protein (TAg). To prepare purified JCV TAg (JCT) for biochemical analyses, the recombinant baculovirus B-JCT was generated by cotransfection of insect cells with wild-type baculovirus and the vector pVL-JCT(Int-) containing the JCT-coding sequence downstream of the efficient polyhedrin promoter. JCT expressed in infected cells was immunoaffinity purified using the anti-JCT monoclonal antibody PAb 2000. Characterization of the viral oncoprotein indicated that it exists in solution as a mixture of monomeric and oligomeric species. With the addition of ATP, the population of monomers decreased and that of hexamers and double hexamers increased. A DNA mobility shift assay indicated that origin binding occurred primarily with the double-hexamer form. A comparison of the specific DNA-binding activities of JCT and SV40 TAg (SVT) revealed that JCT generally exhibited greater affinity for binding site II relative to binding site I (B.S. I) of both viral origin regions, whereas SVT preferentially bound B.S. I. Furthermore, JCT bound nonviral DNA more efficiently than did SVT. These functional differences between the two TAgs may contribute to the reduced DNA replication potential of JCV in vitro, and to the virus' ability to establish persistent infections in vivo.

Antibody against synthetic multiple antigen peptides (MAP) of JC virus capsid protein (VP1) without cross reaction to BK virus: a diagnostic tool for progressive multifocal leukoencephalopathy

Antibody against JC virus (JCV) was raised in rabbits with the use of synthetic multiple antigen peptides. The peptide sequences were derived from three regions of JCV VP1 protein, which showed less similarity with BK virus (BKV) counterpart. The antibodies raised with these peptides were designated as JCAb1, 2 and 3. JCAb1 specifically reacted with JCV and not with BKV, while JCAb2 and 3 reacted both with JCV and BKV. All of these antibodies reacted with JCV antigen of formalin-fixed paraffin sections of progressive multifocal leukoencephalopathy (PML) brain tissue. As JCAb1 is JCV-specific and reacted with JCV in formalin-fixed paraffin sections, it will contribute not only to rapid and accurate immunohistochemical diagnoses of PML but also to clarification of the pathogenesis of JCV infection.

A model for mixed virus disease: co-infection with Moloney murine leukemia virus potentiates runting induced by polyomavirus (A2 strain) in Balb/c and NIH Swiss mice

Polyomavirus was originally isolated by Ludwick Gross from a mixture that also contained a murine retrovirus. A possible pathogenic interaction between polyomavirus and an endogenous mouse retrovirus locus (mtv-7) in polyomavirus-induced cancer has also been reported. To study potential interactive effects of polyomavirus (Py) and Moloney murine leukemia retrovirus (M-MuLV), newborn Balb/c and NIH Swiss mice were infected with high titer wild-type Py (A2 strain) and M-MuLV. Dramatically stunted growth (runting) occurred in 100% of the doubly inoculated mice, while much lower frequency of runting occurred in animals infected with Py alone and not at all with M-MuLV-infected mice. In situ hybridization for Py DNA showed ongoing Py replication and inflammation in kidneys (atypical of most mice singly infected by Py) of runted doubly inoculated mice. In addition, high Py viral replication continued well past the usual acute stage termination. M-MuLV replication was also initially inhibited in bone marrow by simultaneous Py infection. No M-MuLV replication was seen in singly or doubly infected mouse kidneys. Runting was very rapid, observable within 2 days after co-infection, arguing against an adaptive or antigen-specific immunological mechanism. One possibility was that a cytokine-driven acute response mechanism was involved. Supporting this view, RNAse protection assays for various cytokine RNAs showed that several were specifically elevated in kidneys of doubly infected mice. Three patterns were observed: (1) IL-6 was elevated in doubly infected mice early after infection (7 days), but it declined at later times (19 days); (2) IFN-gamma, IL-1 beta, and IL-10 were elevated at both early and late times; and (3) TNF-alpha, IL-12p40, and possibly TNF-beta were elevated only at late times. While the cytokines in the third category might be indicative of infiltrating inflammatory cells, it seems possible that cytokines in the first or second categories might be involved in establishing runting and ongoing polyoma DNA replication in the doubly infected mice.

Biochemical characterization and localization of JC virus large T antigen phosphorylation domains

Large T antigen (T Ag), the major regulatory protein produced by the primate polyomaviruses, is a multifunctional phosphoprotein expressed early in the viral life cycle. T Ag performs many functions essential to viral DNA replication, and studies with SV40 T Ag indicate that the regulation of these functions is modulated, in part, by the phosphorylation status of this oncoprotein. In this study, we demonstrate that JC virus (JCV) T Ag obtained from lytically infected and transformed cells is phosphorylated at serine and threonine residues. Analysis of JCV T Ag via two-dimensional tryptic peptide mapping generates 14 phosphopeptides. Additional mapping studies of intact, hybrid, mutant, and truncated forms of JCV T Ag have aided the localization of phosphorylation sites to the N- or C-terminal region of the protein; both serine and threonine residues are modified at each terminus. The data indicate that, unlike the corresponding regulatory phosphorylation site Ser677 in SV40, Thr664 is not phosphorylated in JCV T Ag. The phosphorylation sites utilized for JCV T Ag, and the regulatory role of these sites, are predicted to contribute to the unique biology of this human virus.

Evaluation of the role of cytokine activation in the multiplication of JC virus (JCV) in human fetal glial cells

The human polyomavirus, JCV, is the etiologic agent of the fatal central nervous system demyelinating disease, progressive multifocal leukoencephalopathy. Progressive multifocal leukoencephalopathy occurs most frequently in patients with underlying immunosuppressive disorders and is the direct result of virus multiplication in oligodendrocytes, the myelin producing cell in the central nervous system. In this report we test the ability of cellular activation signals to modulate expression of the JCV genome in either transfected or infected human fetal glial cells. In addition, we analyze the binding of nuclear proteins isolated from untreated and cytokine treated human fetal glial cells to transcription factor binding sites in the JCV regulatory region. In contrast to the effects of cellular activation on the expression of the HIV-1 promoter in these cells, none of the cellular activators tested increased expression of JCV. The cytokine, TNF-alpha, increased binding of NF kappa B (p50/p65) to a JC NF kappa B site but did not modulate the binding of nuclear proteins to the overlapping NF-1/AP1 region of the JCV enhancer. When taken together these results suggest that the response of JCV to cellular activation signals may be fundamentally different from the response of HIV-1 to these signals in human fetal glial cells and that the JC NF kappa B site may not be required for JCV gene expression or multiplication in vivo.

Expression of human polyomavirus JC T antigen by an adenovirus hybrid vector and its binding to DNA sequences encompassing the JC virus origin of DNA replication

In the search for factors that influence the outcome of human polyomavirus JC (JCV) infection, the roles not only of host-related immunological control but also of virus-dependent regulatory steps have to be taken into account. Besides cell-specific control of early expression of the multifunctional virus protein large tumour antigen (T Ag), control mechanisms involve individual steps of the DNA replication process. For the analysis of T Ag DNA binding, the protein was expressed by an adenovirus hybrid vector in the 293 cell line to provide saturating amounts of JCV T Ag. After determination of the size and immunoreactivity, functional activity was analysed by specific DNA binding. To avoid the interference of cellular proteins, T Ag was immunoprecipitated prior to the reaction. Binding to T Ag-binding sites I and II within a 141 bp DNA segment in the control region was analysed using deletion mutants of a JCV subtype from brain tissue of a patient with fatal central nervous system disease. The specificity of the binding was confirmed by recombinant T Ag binding to origin of DNA replication (ori) sequences of wild-type JCV genomes. These data document that recombinant T Ag overexpressed by the adenovirus vector in eukaryotic cells was JCV-specific, had the expected length and exhibited specific ori-binding activity, thus providing the essential tool for future analysis of virus-host interactions at the level of viral DNA replication.

BK and JC viruses in human immunodeficiency virus type 1-infected persons: prevalence, excretion, viremia, and viral regulatory regions

Human polyomavirus BK (BKV) and JC (JCV) infections were examined in persons infected with human immunodeficiency virus type 1 (HIV-1). High frequencies of BKV (24%) and JCV viruria (16%) were detected by polymerase chain reaction (PCR). BKV viruria was not found in an immunocompetent control group, in contrast to a frequency of JCV viruria of 20%. The degree of HIV-induced immunodeficiency did not influence the prevalence of BKV viruria, in contrast to cytomegalovirus viruria, suggesting BKV reactivation is an early manifestation in HIV infection as well as a temporal sequence of opportunistic infections. BKV DNA but not JCV DNA was detected in peripheral blood mononuclear cells (PBMC) in 2 of 42 subjects by a sensitive nested PCR. Sequencing of viral noncoding control regions (NCCRs) revealed predominantly archetypal and TU type BKV NCCRs but only archetypal JCV NCCRs. A new, naturally occurring BKV NCCR variant was detected in 1 urine specimen and 2 PBMC samples, indicating a stable and biologically significant rearrangement. Serum levels of BKV antibodies do not seem to be diagnostically useful in HIV-infected persons.

Infection of human polyomaviruses JC and BK in peripheral blood leukocytes from immunocompetent individuals

Widely disseminated infection with the human polyomaviruses JC and BK is followed by lifelong asymptomatic viral persistence that can be reactivated under prolonged immunosuppression to fatal CNS and urogenital disease. In an attempt to understand the pathogenesis of polyomavirus diseases, we asked whether leukocytes are involved in polyomavirus infection in the immunocompetent host. Peripheral blood leukocytes from 29 immunocompetent individuals and umbilical cord blood from 10 newborn children were analyzed for the presence of polyomavirus DNA. Southern blot analysis demonstrated the presence of JCV-specific full-length virus genomes and indicated involvement of the second human polyomavirus BK. In contrast to specimens from newborn children, PCR amplification of target DNA in the adult age group followed by species-specific hybridization provided evidence of concomitant JCV and BKV infection in almost all specimens. Nucleotide sequencing of virus-specific products representing DNA segments essential for virus multiplication confirmed presence of both virus species in leukocytes. The detection of a new virus subtype and single base changes or deletions in the noncoding DNA region from individual cases suggested widespread heterogeneity in the circulating virus population, although the structure of the transcriptional control elements in all cases was comparable to highly active elements found in lytically infected cells. Those findings and the localization of both virus types in the nuclei of blood cells by in situ hybridization demonstrate that JCV and BKV frequently infect peripheral leukocytes and give strong evidence that leukocytes are common sites of polyomavirus persistence in healthy individuals.

PAb1614, a monoclonal antibody reactive with the tumor antigens of SV40, JC, BK, and polyoma virus, and other JC virus tumor antigen cross-reactive antibodies of the PAb1601-1636 panel

PAb1614, an SV40-specific monoclonal antibody of the panel PAb1601-1636 reacts with large and small tumor antigens of SV40, BK and JC virus, and with polyoma virus large and middle tumor antigens, but not with the large tumor antigen of the lymphotropic papova virus. Using immunofluorescence and immunoblot competition assays and ELISA with synthetic peptides, it is shown that the epitope is represented by the SV40 tumor antigen undecapeptide, K39-E49. This peptide comprises the tumor antigen consensus sequence, H42-G47, of the polyoma viruses. However, the epitope of PAb1614 probably does not exactly coincide with this hexapeptide. This explains why some cross-reactions are less strong, or absent, as in the case of the lymphotropic papova virus. Further antibodies of the PAb1601-1636 panel that cross-react with the JC virus large tumor antigen are PAb1602, 1604, 1606, 1618, 1621, 1622, 1623, 1624, 1626, 1629, and 1633.

BK virus infection of the human urinary tract

By screening consecutive autopsy cases with an antibody that recognizes human polyomaviruses, we found a case of malignant lymphoma in which the virus infection was confined to epithelia of the renal calyces, renal pelvis, ureter, and urinary bladder. The virus was confirmed as BK virus by a specific monoclonal antibody against BK virus T antigen, and numerous virus particles were identified by electron microscopy. The results showed that BK virus is a human urotheliotrophic virus.

Large T-antigen and sequences within the regulatory region of JC virus both contribute to the features of JC virus DNA replication

The requirements for the DNA replication of the human papovavirus JC were analyzed using JC T-antigen as well as the T-antigens of the related viruses SV40 and BK. With all three T-antigens, the boundary of the core origin mapped on the early side to position 5093 of the viral genome. In conjunction with earlier studies, the core origin of DNA replication was therefore defined as a 68-bp region which, similar to the SV40 core origin, contains three major structural elements, early palindrome, T-antigen binding site II, and A/T-rich tract. Replication was stimulated by sequences flanking the core origin on the early side. Specifically, the stimulating sequences on the early side were identified as T-antigen binding site I. The degree to which flanking sequences were able to stimulate viral DNA replication was dependent on the T-antigen used in the experiment, with JC T-antigen relying most and BK T-antigen relying least on the flanking sequences. SV40 T-antigen showed an intermediate dependence. The same hierarchy was observed when replication activities were compared. BK T-antigen was more active in replicating DNA than SV40 T-antigen, which in turn was more effective than JC T-antigen. Dependence on flanking sequences is, thus, inversely correlated to the replicating activity of the respective T-antigen, showing that, in addition to the origin, the T-antigen contributes to the characteristics of JC virus DNA replication.

[A unilateral large demyelinating lesion in the cerebral white matter with slowly progressive hemiplegia and intrathecal JC virus antibody production]

A 59-year-old male patient presented in 1991 with left-sided hemiplegia and hemihypesthesia and left homonymous hemianopsia, which had developed for the preceding 12 months. The cerebrospinal fluid (CSF) level of protein was mildly elevated, oligoclonal IgG band was initially negative, but finally positive and myelin basic protein was absent. Magnetic resonance imaging and X-ray computed tomography (CT) of the brain revealed a unilateral demarcated lesion extending around the posterior horn and triagular part of the right lateral ventricle, apparently capped by remarkably gadolinium enhancement at its front, which had no mass effect, and several small isolated plaques were also observed in other areas of the brain. All lesions appeared as high intensity areas on T2 weighted images and hypodense areas on CT. The JC virus hemagglutination-inhibition antibody titers were 1:32 in serum and 1:8 in CSF; the antibody titer ratio and index both suggested an intrathecal antibody production. Pathological examination of brain biopsy specimen taken from the large lesion demonstrated profound demyelination with preservation of axons, a large number of macrophages and spotted perivascular lymphocyte cuffings. Based on this experience, we discussed the features in this case which differentiated it from multiple sclerosis, leukodystrophy and typical progressive multifocal leukoencephalopathy (PML). Diffuse-disseminated sclerosis or transitional sclerosis was most likely so far as the clinical picture, imaging and histology were concerned. However, we implicated the possible involvement of JC virus infection to the etio-pathogenesis of the demyelinating lesions in view of the intrathecal JC virus antibody production in CSF observed in this case.(ABSTRACT TRUNCATED AT 250 WORDS)

[BK and JC viruses--2 polyomaviruses causing disease in immunosuppressed patients]

BK and JC viruses are two polyoma viruses designated by the initials of the patients from whom they were first isolated. After the primary infection, usually occurring in childhood or early school age, the viruses become latent. Reactivation occurs during immunosuppression, and the BK virus has been shown to be the main cause of viral hemorrhagic cystitis in bone marrow transplanted patients, while the JC virus has been found to cause progressive multifocal leukoencephalopathy, PML. The paper consists in a report of results obtained with an established method for the amplification of BK and JC virus DNA. Of 20 urine specimens from patients with hemorrhagic cystitis, 13 were found to be BK virus-positive. Post-transplantation follow-up shows that the virus continues to remain detectable for long periods. JC virus positivity was found in central nervous system material (a cerebrospinal spinal fluid specimen in one case) from two PML patients.

An M-antibody capture radioimmunoassay (MACRIA) for detection of JC virus-specific IgM

A solid-phase M-antibody capture radioimmunoassay (MACRIA) for detecting JC-specific IgM is described. The assay is based on a JC-specific monoclonal antibody (17.7.6) and Nonidet P40-treated, glycine-extracted antigen. MACRIA is more sensitive for JC IgM detection than haemagglutination inhibition (HI) following serum fractionation on a sucrose density gradient, and can be applied to large numbers of sera. The specificity of the assay was confirmed by examining sera from several acute virus infections and also those containing rheumatoid factor. Sera collected from renal transplant recipients with known active JC virus infection were found to contain more than 5 units of JC IgM. In this group of patients JC IgM represents either primary or reactivated JC infection. JC IgM was detected by MACRIA in 15 of 100 unselected blood donors, indicating that JC IgM is frequently produced in healthy seropositive individuals. Thirteen of the 15 sera positive from blood donors contained only low levels of JC IgM (< 5 units), but the specificity of all these results was confirmed in a blocking assay. It is suggested that these low levels of JC IgM may occur in up to 28% of seropositive individuals and result from active JC antigenic stimulation in healthy immunocompetent adults.

Antibody response to human papovavirus JC (JCV) and simian virus 40 (SV40) T antigens in SV40 T antigen-transgenic mice

Human papovavirus JC (JCV) and simian virus 40 (SV40) genomes share approximately 69% homology; and there is antigenic cross-reactivity between JCV and SV40 tumor or T antigens. In order to determine whether a selective immune response to JCV T antigen could be demonstrated, transgenic mice (SV11+) that express SV40 T antigen in the choroid plexus and are partially tolerant to antigenic determinants on SV40 T antigen were immunized with SV40 or JCV T antigens and their antibody responses were analyzed. The results show that SV11+ mice responded as well as their nontransgenic litter mates to JCV T antigen. Monoclonal antibodies were derived from hybridomas generated from immunized mice which reacted specifically with epitopes in the amino and carboxy terminal halves on JCV T antigen. These studies show that transgenic mice expressing SV40 T antigen are capable of responding to determinants not shared between JCV and SV40 T antigen.

Brain vascular endothelial cells express JC virus large tumor antigen in immunocompetent and cyclophosphamide-treated hamsters

When injected intracerebrally into newborn hamsters, the human polyomavirus JC virus (JCV) establishes a nonproductive infection resulting in brain tumor formation. Using immunostaining methods to detect the JCV regulatory protein, large tumor antigen (T antigen), we have now demonstrated JCV infection of brain vascular endothelial cells (EC) in infected hamsters. JCV T antigen was detected in lectin-labeled EC as well as in von Willebrand factor-expressing EC in both cyclophosphamide-treated and nonimmunosuppressed hamster brains 16, 21, and 31 days after birth. Cyclophosphamide-treated hamsters exhibited a greater number of JCV-infected EC, whereas T-antigen expression in nonvascular cells was not affected. The influence of cyclophosphamide was most pronounced in the cerebellum where increased numbers of JCV-infected EC were located predominantly at the internal granular layer-white matter junction, also a prominent location for T-antigen-expressing neoplastic foci. The hamster model demonstrates in vivo infection of EC by a human polyomavirus and directs interest toward the role of these cells in human JCV infection.