HTLV-I-associated myelopathy: oligoclonal immunoglobulin G bands contain anti-HTLV-I p24 antibody

Novel insights into human T-lymphotropic virus type-1 (HTLV-1) pathogenesis-host interactions in the manifestation of HTLV-1-associated myelopathy/tropical spastic paraparesis

Human T-lymphotropic virus type-1 (HTLV-1) was the first discovered human oncogenic retrovirus, the etiological agent of two serious diseases have been identified as adult T-cell leukaemia/lymphoma malignancy and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a debilitating chronic neuro-myelopathy. Despite more than 40 years of molecular, histopathological and immunological studies on HTLV-1-associated diseases, the virulence and pathogenicity of this virus are yet to be clarified. The reason why the majority of HTLV-1-infected individuals (∼95%) remain asymptomatic carriers is still unclear. The deterioration of the immune system towards oncogenicity and autoimmunity makes HTLV-1 a natural probe for the study of malignancy and neuro-inflammatory diseases. Additionally, its slow worldwide spreading has prompted public health authorities and researchers, as urged by the WHO, to focus on eradicating HTLV-1. In contrast, neither an effective therapy nor a protective vaccine has been introduced. This comprehensive review focused on the most relevant studies of the neuro-inflammatory propensity of HTLV-1-induced HAM/TSP. Such an emphasis on the virus-host interactions in the HAM/TSP pathogenesis will be critically discussed epigenetically. The findings may shed light on future research venues in designing and developing proper HTLV-1 therapeutics.

Human T Lymphotropic Virus 1-Associated Myelopathy: Overview of Human T Cell Lymphotropic Virus-1/2 Tests and Potential Biomarkers

Human T cell lymphotropic virus (HTLV)-1-associated myelopathy is a chronic, disabling inflammatory disorder of the spinal cord caused by HTLV-1 infection. The diagnosis of HTLV-1-associated myelopathy (HAM) is based on clinical and laboratorial findings. The disease is characterized by the presence of spastic paraparesis associated with detection of anti-HTLV-1 antibodies or HTLV-1 genomes in blood and cerebrospinal fluid (CSF). New inflammatory markers have been proposed for the diagnosis and assessment of the prognosis of HAM. We reviewed the laboratory diagnostic and potential surrogate markers for HAM. The serological screening tests for detection of anti-HTLV-1/2 antibodies are highly sensitive and specific, but confirmation and typing of HTLV-1 or HTLV-2 infection by other serological or molecular methods are essential. Detection of intrathecal anti-HTLV-1 antibodies and quantification of the HTLV-1 provirus in CSF provide additional evidence for diagnosis especially in atypical cases or where alternative causes of neuroinflammation cannot be excluded. The CXC motif chemokine ligand 10 and neopterin in serum and CSF are now emerging as inflammatory markers with prognostic value and for HAM monitoring and management. In addition, measures of neurodegeneration, such as neurofilament light chain in the CSF and blood, may also contribute to the HAM prognosis. This review is useful for clinicians and researchers evaluating potential benefits and limitations of each biomarker in clinical practice. The advent of new markers makes it necessary to update the criteria for the best evidence-based approach and for worldwide consensus regarding the use of diagnostic and surrogate markers for HAM.

B cells going viral in the CNS: Dynamics, complexities, and functions of B cells responding to viral encephalitis

A diverse number of DNA and RNA viruses have the potential to invade the central nervous system (CNS), causing inflammation and injury to cells that have a limited capacity for repair and regeneration. While rare, viral encephalitis in humans is often fatal and survivors commonly suffer from permanent neurological sequelae including seizures. Established treatment options are extremely limited, predominantly relying on vaccines, antivirals, or supportive care. Many viral CNS infections are characterized by the presence of antiviral antibodies in the cerebral spinal fluid (CSF), indicating local maintenance of protective antibody secreting cells. However, the mechanisms maintaining these humoral responses are poorly characterized. Furthermore, while both viral and autoimmune encephalitis are associated with the recruitment of diverse B cell subsets to the CNS, their protective and pathogenic roles aside from antibody production are just beginning to be understood. This review will focus on the relevance of B cell responses to viral CNS infections, with an emphasis on the importance of intrathecal immunity and the potential contribution to autoimmunity. Specifically, it will summarize the newest data characterizing B cell activation, differentiation, migration, and localization in clinical samples as well as experimental models of acute and persistent viral encephalitis.

Immunophenotypic characterization of CSF B cells in virus-associated neuroinflammatory diseases

Intrathecal antibody synthesis is a well-documented phenomenon in infectious neurological diseases as well as in demyelinating diseases, but little is known about the role of B cells in the central nervous systems. We examined B cell and T cell immunophenotypes in CSF of patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) compared to healthy normal donors and subjects with the other chronic virus infection and/or neuroinflammatory diseases including HIV infection, multiple sclerosis (MS) and progressive multifocal leukoencephalopathy. Antibody secreting B cells (ASCs) were elevated in HAM/TSP patients, which was significantly correlated with intrathecal HTLV-1-specific antibody responses. High frequency of ASCs was also detected in patients with relapsing-remitting multiple sclerosis (RRMS). While RRMS patients showed significant correlations between ASCs and memory follicular helper CD4+ T cells, CD4+CD25+ T cells were elevated in HAM/TSP patients, which were significantly correlated with ASCs and HTLV-1 proviral load. These results highlight the importance of the B cell compartment and the associated inflammatory milieu in HAM/TSP patients where virus-specific antibody production may be required to control viral persistence and/or may be associated with disease development.

Role of HTLV-1 Tax and HBZ in the Pathogenesis of HAM/TSP

Human T cell lymphotropic virus type 1 (HTLV-1) infection can lead to development of adult T cell leukemia/lymphoma (ATL) or HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in a subset of infected subjects. Understanding the interaction between host and HTLV-1 and the molecular mechanisms associated with disease pathogenesis is critical for development efficient therapies. Two HTLV-1 genes, tax and HTLV-1 basic leucine zipper factor (HBZ), have been demonstrated to play important roles in HTLV-1 infectivity and the growth and survival of leukemic cells. Increased HTLV-1 Tax expression induces the expression of various cellular genes such as IL-2 and IL-15, which directly contributes to lymphocyte activation and immunopathogenesis in HAM/TSP patients. However, little is known about the molecular and cellular mechanism of HBZ in development of HAM/TSP. It has been reported that HBZ mRNA expression was detected in HAM/TSP patients higher than in asymptomatic carriers and correlated with proviral load and disease severity. Unlike HTLV-1 tax, HBZ escapes efficient anti-viral immune responses and therefore these reactivities are difficult to detect. Thus, it is important to focus on understanding the function and the role of HTLV-1 tax and HBZ in disease development of HAM/TSP and discuss the potential use of these HTLV-1 viral gene products as biomarkers and therapeutic targets for HAM/TSP.

A Neuroprimer: Principles of Central Nervous System Immunity

Despite longstanding perceptions, robust innate and adaptive immune responses occur within the central nervous system (CNS) in response to infection and tissue damage. Although necessary to control infection, immune responses can lead to severe CNS pathology in the context of both viral infection and autoimmunity. Research into how the central nervous and immune systems communicate has accelerated over the past 20 years leading to a better understanding of pathways controlling immune activation and neuroinflammation that have guided the approval of new disease-modifying therapies to treat CNS immunopathology, particularly the inflammatory demyelinating disease multiple sclerosis. This article provides an introduction into the basic principles underlying immune responses within the CNS that developed from experimental animal models of both neurotropic virus infection and autoimmune T cell-mediated CNS demyelination.

Diagnosis of multiple sclerosis

This chapter will serve as a guide for the diagnosis of multiple sclerosis (MS). Primary aims include a review of both the common and atypical clinical manifestations of MS, a detailed discussion of the alternative diagnoses which can mimic MS, as well as a review of the current established diagnostic criteria and a history of their development. It will also review the distinct disease courses and MS variants. The goal of the chapter is to facilitate the diagnostic process for clinicians so that they may expedite early diagnosis and treatment in an effort to alter disease outcomes and ultimately improve patients' quality of life.

Standardisation of Western blotting to detect HTLV-1 antibodies synthesised in the central nervous system of HAM/TSP patients

Intrathecal synthesis of human T-lymphotropic virus type 1 (HTLV-1) antibodies (Abs) represents conclusive evidence of a specific immune response in the central nervous system of HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients. Western blotting (WB) for HTLV Abs in serum is a confirmatory test for HTLV-1 infection. The aim of this study was to standardise the Western blot to demonstrate the intrathecal pattern of Abs against HTLV-1 proteins in HAM/TSP patients. Paired cerebrospinal fluid (CSF) and serum samples were selected from 20 patients with definite HAM/TSP, 19 HTLV-1 seronegative patients and two HTLV-1 patients without definite HAM/TSP. The presence of reactive bands of greater intensity in the CSF compared to serum (or bands in only the CSF) indicated the intrathecal synthesis of anti-HTLV-1 Abs. All definite HAM/TSP patients presented with an intrathecal synthesis of anti-HTLV-1 Abs; these Abs were not detected in the control patients. The most frequent intrathecal targets of anti-HTLV-1 Abs were GD21, rgp46-I and p24 and, to a lesser extent, p19, p26, p28, p32, p36, p53 gp21 and gp46. The intrathecal immune response against env (GD21 and rgp46-I) and gag (p24) proteins represents the most important humoral pattern in HAM/TSP. This response may be used as a diagnostic marker, considering the frequent association of intrathecal anti-HTLV-1 Ab synthesis with HAM/TSP and the pathogenesis of this neurological disease.

Humoral immune response to HTLV-1 basic leucine zipper factor (HBZ) in HTLV-1-infected individuals

Background

Human T cell lymphotropic virus type 1 (HTLV-1) infection can lead to development of adult T cell leukemia/lymphoma (ATL) or HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in a subset of infected subjects. HTLV-1 basic leucine zipper factor (HBZ) gene has a critical role in HTLV-1 infectivity and the development of ATL and HAM/TSP. However, little is known about the immune response against HBZ in HTLV-1-infected individuals. In this study, we examined antibody responses against HBZ in serum/plasma samples from 436 subjects including HTLV-1 seronegative donors, asymptomatic carriers (AC), ATL, and HAM/TSP patients using the luciferase immunoprecipitation system.

Results

Immunoreactivity against HBZ was detected in subsets of all HTLV-1-infected individuals but the test did not discriminate between AC, ATL and HAM/TSP. However, the frequency of detection of HBZ-specific antibodies in the serum of ATL patients with the chronic subtype was higher than in ATL patients with the lymphomatous subtype. Antibody responses against HBZ were also detected in cerebrospinal fluid of HAM/TSP patients with anti-HBZ in serum. Antibody responses against HBZ did not correlate with proviral load and HBZ mRNA expression in HAM/TSP patients, but the presence of an HBZ-specific response was associated with reduced CD4⁺ T cell activation in HAM/TSP patients. Moreover, HBZ-specific antibody inhibited lymphoproliferation in the PBMC of HAM/TSP patients.

Conclusions

This is the first report demonstrating humoral immune response against HBZ associated with HTLV-I infection. Thus, a humoral immune response against HBZ might play a role in HTLV-1 infection.

Signature biochemical properties of broadly cross-reactive HIV-1 neutralizing antibodies in human plasma

The common properties of broadly cross-reactive HIV-1 neutralization antibodies found in certain HIV-1-infected individuals holds significant value for understanding natural and vaccine-mediated anti-HIV immunity. Recent efforts have addressed this question by deriving neutralizing monoclonal anti-envelope antibodies from memory B cell pools of selected subjects. However, it has been more difficult to identify whether broadly neutralizing antibodies circulating in plasma possess shared characteristics among individuals. To address this question, we used affinity chromatography and isoelectric focusing to fractionate plasma immunoglobulin from 10 HIV-1-infected subjects (5 subjects with broad HIV-1 neutralizing activity and 5 controls). We find that plasma neutralizing activity typically partitions into at least two subsets of antibodies. Antibodies with restricted neutralization breadth have relatively neutral isoelectric points and preferentially bind to envelope monomers and trimers versus core antigens from which variable loops and other domains have been deleted. In comparison, broadly neutralizing antibodies account for a minor fraction of the total anti-envelope response. They are consistently distinguished by more basic isoelectric points and specificity for epitopes shared by monomeric gp120, gp120 core, or CD4-induced structures. Such biochemical properties might be exploited to reliably predict or produce broad anti-HIV immunity.

Role of B Cells in Pathogenesis of Multiple Sclerosis

Despite the current limited understanding of the etiology of multiple sclerosis (MS), genetic susceptibility and environmental influences are known driving factors. MS is considered a T-cell-mediated disease given the prevalence of T cells in plaques. Plaque formation is characteristic of this disease attributable to immune mechanisms, triggered by an autoimmune attack aimed at antigens in the myelin sheath or oligodendrocyte proteins. The attack consists of the following: The role of the B cells is twofold: first, as autoreactive B cells they produce autoantibodies, secrete cytokines, clonally replicate memory B cells, and long-living plasma cells which serve to advance the diseased state by their constant production of autoantibodies. Second, as antigen-presenting cells they activate the autoreactive T cells. For this reason, the stipulation that T cell is the cornerstone of MS must be reevaluated. Various studies on pathogenesis of MS have indicated that B cells, as the humoral component of the adaptive immune system, are active participants in pathogenesis and lesion maintenance throughout the disease process. The active role of B cells and autoantibodies makes them an encouraging therapeutic target. Advances in the understanding of B-cell development and activity would allow for an enhanced strategy in the design of autoimmune treatment. For this reason, further investigation is necessary to determine whether depletion of B cells or antibodies may restore immune function.

The B cell response in multiple sclerosis

Multiple sclerosis (MS) plaques and CSF contain increased amounts of intrathecally synthesized IgG, manifest as oligoclonal bands (OCBs) after protein electrophoresis. OCBs are not unique to MS and are also produced in infectious diseases of the CNS, in which the oligoclonal IgG has been shown to be antibody directed against the disease-causing agent. Thus, analysis of antibody specificity may identify the causative agent/antigen in MS. This review discusses recent studies that have analyzed the phenotypes of B cells in MS which infiltrate the CNS and the molecular features of their antigen-binding regions. Together with histologic studies showing the presence of ectopic lymphoid follicles in the meninges of some MS patients, this data supports the notion of a targeted and compartmentalized humoral response in MS.

Identification of Epstein-Barr virus proteins as putative targets of the immune response in multiple sclerosis

MS is a chronic inflammatory and demyelinating disease of the CNS with as yet unknown etiology. A hallmark of this disease is the occurrence of oligoclonal IgG antibodies in the cerebrospinal fluid (CSF). To assess the specificity of these antibodies, we screened protein expression arrays containing 37,000 tagged proteins. The 2 most frequent MS-specific reactivities were further mapped to identify the underlying high-affinity epitopes. In both cases, we identified peptide sequences derived from EBV proteins expressed in latently infected cells. Immunoreactivities to these EBV proteins, BRRF2 and EBNA-1, were significantly higher in the serum and CSF of MS patients than in those of control donors. Oligoclonal CSF IgG from MS patients specifically bound both EBV proteins. Also, CD8(+) T cell responses to latent EBV proteins were higher in MS patients than in controls. In summary, these findings demonstrate an increased immune response to EBV in MS patients, which suggests that the virus plays an important role in the pathogenesis of disease.

B cells in multiple sclerosis

The most common laboratory abnormality in multiple sclerosis (MS) is an increased amount of cerebrospinal fluid IgG and the presence of oligoclonal bands. Despite studies of the humoral response that suggest the involvement of an infectious agent or autoantigen in disease, the major targets of the oligoclonal response are still unknown. Identification of these targets will reveal valuable insights into the cause and pathogenesis of MS and is likely to lead to effective treatment.

Oligoclonal immunoglobulins in cerebrospinal fluid during varicella zoster virus (VZV) vasculopathy are directed against VZV

Limited analyses of cerebrospinal fluid from patients with central nervous system infections have shown that the oligoclonal IgG is antibody directed against the agent that causes disease. Using a new method involving binding of IgG to beads coated with lysates prepared from candidate infectious antigens, we showed that the oligoclonal IgG in cerebrospinal fluid of a patient with chronic varicella zoster virus vasculopathy is directed against the causative virus. This approach holds promise in identifying and purifying the relevant oligoclonal IgGs in inflammatory central nervous system diseases of unknown cause.

HTLV-1-mediated immunopathological CNS disease

HAM/TSP is a chronic inflammatory disease of the spinal cord. It is rather rare in HTLV-1-infected individuals. Immunogenetic factors of the HLA complex have been identified that support or prevent the development of the disease. In HAM/TSP patients a characteristic constellation of high proviral loads and increased cellular and humoral immune responses have been established. Immune dysfunction in HAM/TSP patients might be partly explained by HTLV-1 tax p40 transactivation of cellular genes in infected CD4+ T lymphocytes. The oligoclonal expansion of infected T lymphocytes, the variation of tax p40 within HTLV-1 carriers, and the regulation of proviral gene expression are possible determinants for disease development and need to be clarified in future studies.

Antigen discovery in chronic human inflammatory central nervous system disease: panning phage-displayed antigen libraries identifies the targets of central nervous system-derived IgG in subacute sclerosing panencephalitis

The presence of increased IgG in the brains of humans with infectious and inflammatory CNS diseases of unknown etiology such as multiple sclerosis may be a clue to the cause of disease. For example, the intrathecally synthesized oligoclonal bands in diseases such as subacute sclerosing panencephalitis (SSPE) or cryptococcal meningitis have been shown to represent Ab directed against the causative agents, measles virus (MV), or Cryptococcus neoformans, respectively. Using SSPE as a model system, we developed a strategy to identify the antigenic targets of the intrathecal disease-relevant IgG in chronic human inflammatory and demyelinating diseases of the CNS. Libraries of cDNA Ags were displayed on the surface of T7Select bacteriophage and biopanned on IgG extracted from the brain of an SSPE patient, or on a monospecific recombinant Fab identified from SSPE brain. After three or six rounds of biopanning on either Ab, positive phage-displayed Ags reacting with IgG were enriched to 35-77% of all panned clones. Sequence analysis of the positive clones identified fragments of the nucleocapsid protein of MV, the cause of SSPE. The sensitivity of the system was determined by diluting the positive clones from this SSPE phage-displayed library at a ratio of 10(-6) into another phage-displayed library that did not contain any detectable MV Ags; after six rounds of panning, the positive clones comprised 34% of all phage and were also shown to be MV nucleocapsid specific. This strategy will be useful to identify potentially rare Ags in diseases of unknown cause.

Global epidemic of human T-cell lymphotropic virus type-I (HTLV-I)

Infection with human T-cell lymphotrophic virus-I (HTLV-I) is now a global epidemic, affecting 10 million to 20 million people. This virus has been linked to life-threatening, incurable diseases: adult T-cell leukemia/lymphoma (ATLL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The cumulative lifetime risk of developing these incurable diseases is approximately 5% in asymptomatic patients. For the emergency physician practicing among patients from high-risk groups, HTLV-I and its associated diseases are presenting an increasing challenge. This report describes its transmission, seroprevalence, treatment, and methods of controlling spread of this retrovirus. Coinfection with HTLV-I and HIV has been shown to accelerate the progression of acquired immune deficiency syndrome (AIDS).

Cloning the Antibody Response in Humans with Inflammatory Central Nervous System Disease: Analysis of the Expressed IgG Repertoire in Subacute Sclerosing Panencephalitis Brain Reveals Disease-Relevant Antibodies That Recognize Specific Measles Virus Antigens

The presence of increased IgG in the brains of humans with infectious and inflammatory CNS diseases of unknown etiology such as multiple sclerosis may be a clue to the cause of disease. For example, the intrathecally synthesized oligoclonal bands (OGBs) in diseases such as subacute sclerosing panencephalitis (SSPE) or cryptococcal meningitis have been shown to represent Ab directed against the causative agents, measles virus (MV) or Cryptococcus neoformans, respectively. Using SSPE as a model system, we have developed a PCR-based strategy to analyze the repertoire of IgG V region sequences expressed in SSPE brain. We observed abnormal expression of germline V segments, overrepresentation of particular sequences that correspond to the oligoclonal bands, and substantial somatic mutation of most clones from the germline, which, taken together, constitute features of Ag-driven selection in the IgG response. Using the most abundant or most highly mutated γ H chain and κ or lambda L chain sequences in various combinations, we constructed functional Abs in IgG mammalian expression vectors. Three Abs specifically stained MV-infected cells. One Ab also stained cells transfected with the MV nucleoprotein, and a second Ab stained cells transfected with the MV-fusion protein. This technique demonstrates that functional Abs produced from putative disease-relevant IgG sequences can be used to recognize their corresponding Ags.

Extraction and purification of active IgG from SSPE and MS brain

Immunoglobulin (Ig) G was purified from soluble and membrane fractions of postmortem subacute sclerosing panencephalitis (SSPE) brain, multiple sclerosis (MS) brain plaque-periplaque white matter, and normal human brain (NHB) white matter. After homogenization in 0.32 M sucrose and removal of cell debris and nuclei by low-speed centrifugation, soluble and crude membrane fractions were separated by ultracentrifugation. After removal of sucrose by dialysis, IgG was isolated from the soluble fraction by protein A affinity chromatography. IgG was obtained from the membrane fraction by elution at low pH and purification from the eluate by protein A chromatography. Whereas very little IgG was in NHB white matter, significant levels of IgG were recovered from both SSPE and MS brain. Both immunocytochemical staining of measles virus-infected cells in tissue culture and protein immunoblotting of virus-infected cell lysates showed that the IgG from SSPE brain contained activity specific for measles virus protein. The abundance, purity and functional activity of IgG extracted from SSPE and MS brain indicate that IgG extracted from the brain of humans with an inflammatory disease of unknown etiology can be used to identify its corresponding antigen.

In vitro virus propagation and high cellular responsiveness to the infected cells in patients with HTLV-I-associated myelopathy (HAM/TSP)

The reasons for the development of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in certain infected individuals remain poorly understood, but the susceptibility should involve both viral factors and host conditions. To assess simultaneously both virus-induced activation of infected cells and the cellular response to virus producing cells, an analysis of fractionated peripheral blood lymphocytes obtained from patients with HAM/TSP (n = 15) were compared with those of asymptomatic HTLV-I carriers (n = 9) in an age-matched manner. The in vitro propagation of HTLV-I infection was evaluated as the spontaneous thymidine incorporation into CD4+ cells, and proliferative response of CD8+ cells against cultured and irradiated autologous CD4+ cells was employed to analyze the HTLV-I-induced cellular response. The comparative analysis using these two parameters demonstrated that HAM/TSP patients were characterized by the concomitance of a high inducibility of HTLV-I propagation and a high cellular responsiveness against HTLV-I as compared with asymptomatic HTLV-I carriers, suggesting the involvement of both of these factors in disease susceptibility. In addition, the coupled evaluation of these two in vitro phenomena may offer a better diagnostic hallmark for HTLV-I seropositive myelopathy cases with other known cause of myelopathy.

[Cerebrospinal fluid analysis and the pathogenesis of central nervous system infection by HTLV-I]

The immunopathogenesis of the HTLV-I associated myelopathy (HAM) may be studied by the CSF evaluation. The mechanism of this myelopathy remains unknown. The disturbs of the cellular and humoral immune response observed in HAM patients suggest that the immunological derangement may contribute to the disease mechanisms. For hypothesis, the migration of infected lymphocytes through the blood-brain barrier could have a main role at the pathogenesis of HAM. An increase of the production of cytokines as tumor necrosis factor alpha (TNF alpha) contributes to the migration of lymphocytes through the expression of the intercellular adhesion molecule on the surface of the endothelial cells. On the other side, new knowledges suggest that the imbalance between the production of TNF alpha and its soluble receptor (sTNF-R) could result in the lesive effects of this cytokine in the central nervous system.

The search for virus in multiple sclerosis brain

Plaque-periplaque areas from MS brain tissue were explanted and propagated in tissue culture. The same in vitro techniques that successfully rescued measles virus from SSPE brain, papovavirus from PML brain, and HSV from normal human trigeminal ganglia, were applied. MS brain cells were also inoculated into chimpanzees, multiple rodent species, and embryonated hens eggs. No neurologic disease developed in experimentally infected animals, and no cytopathic effect was observed in explanted cells, or after cocultivation or fusion of MS brain cells with indicator cells. Further analysis of explanted and cocultivated cells by indirect immunofluorescence with various antiviral antisera prepared against viruses associated with post-infectious encephalomyelitis, as well as antisera to other ubiquitous viruses, failed to detect viral antigen. Finally, attempts to detect a latent enveloped virus in MS brain cells by 'superinfecting' MS brain cells in culture with vesicular stomatitis virus (VSV) did not reveal a VSV non-neutralizable fraction. Nevertheless, since oligoclonal bands (OGBs) in the CSF of patients with chronic infectious diseases of the CNS are directed against the causative agent, it is likely that OGBs in MS CSF are antibody directed against the agent or antigen that triggered disease. Although the relevant antibody may be scarce relative to irrelevant antibody in MS CSF, and only small amounts of an MS-specific antigen may be present in brain, this report provides a rationale for strategies proposed in our companion report by Owens et al which will allow detection of an MS-specific antigen or its cognate RNA in brain.

Human T-cell lymphotropic virus type-I infection in the severe combined immunodeficiency mouse

Human T-cell lymphotropic virus type-I (HTLV-I) is the etiologic agent of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukemia (ATL). HAM/TSP and ATL occur infrequently among HTLV-I-infected individuals, and rarely develop in the same individual. To study host and viral factors involved in the induction, tissue tropism, as well as pathogenesis of HAM/TSP, peripheral blood lymphocytes (PBL) from 14 patients with HAM/TSP and from 9 controls were introduced into severe combined immunodeficiency (SCID) mice by intraperitoneal injection. Mice were followed for up to 26 weeks. Human IgG was produced from 2 to 14 weeks after reconstitution in all animals. Thirty-two of 44 mice (72%) showed circulating human antibody against the major viral protein products of HTLV-I. Analysis of viral sequences by polymerase chain reaction (PCR) demonstrated HTLV-I sequences in 21/38 (55%) brains and in 7/17 (41%) spinal cords from HTLV-I-hu SCID mice. No animal had clinical evidence of neurological impairment or pathological findings similar to those seen in HAM/TSP. Seven mice who received PBL from Epstein Barr virus (EBV)-seropositive patients developed an intraperitoneal lymphoma. In 2 mice an infiltration of brain by a lymphoblastic tumor of B/T cell type was observed. By PCR, all the tumors were EBV-positive; HTLV-I sequences were detected in 5 of them. Our study suggests that the HTLV-I-hu-SCID mouse provides a potentially valuable system for studying the production, kinetics, and pathogenicity of anti-HTLV-I antibody, and may help clarify the interaction of EBV and retroviruses in the development of disease.

Diversity of intrathecal antibody synthesis against HTLV-I and its relation to HTLV-I associated myelopathy

The humoral immune response against human T-cell lymphotropic virus type I (HTLV-I) in the central nervous system (CNS) compartment and in the blood was investigated by enzyme immunoassay using 16 synthetic peptides corresponding to HTLV-I core and envelope sequences. We evaluated paired samples of cerebrospinal fluid and serum from HTLV-I seropositive Japanese patients, classified as follows: HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP; n = 39), patients with spinal cord disease ascribed to either HAM/TSP or to some concomitant, HTLV-I-unrelated disease (possible HAM/TSP; n = 6) or carriers without any clinical signs of HAM/TSP (n = 15). HTLV-I-peptide-specific intrathecal antibody synthesis was found in 79% of HAM/TSP patients, but only in 20% of carriers without HAM/TSP. The group of carriers without HAM/TSP showed local synthesis for some peptides (on average 0.3 peptides per patient). In most HAM/TSP patients, however, there was a diverse intrathecal immune response to several HTLV-I synthetic peptides (on average against 3.6 peptides per HAM/TSP patient), most frequently against gag p19 100-130, env gp21 458-488, and env gp46 175-199 and 288-317. The intrathecal antibody synthesis against several HTLV-I determinants may represent a pathogenic immune response in HAM/TSP and is possibly related to the infiltration of virus-infected T-cells in the spinal cord.

Specificity of intrathecal IgG synthesis for HTLV-1 core and envelope proteins in HAM/TSP

INTRODUCTION

In patients with human T-cell lymphotropic virus type 1 (HTLV-1) associated myelopathy/tropical spastic paraparesis (HAM/TSP), we investigated the significance of HTLV-1 specific antibodies in the cerebrospinal fluid (CSF).

MATERIAL AND METHODS

The quantities of HTLV-1 specific immunoglobulin G (IgG) in paired CSF and serum were evaluated by a sensitive enzyme immunoassay (EIA). The specificity of antiviral IgG was determined by radioimmunoprecipitation of HTLV-1 antigens.

RESULTS

In 17 of 20 HAM/TSP patients, quantitative evaluation by EIA supplied evidence for antiviral IgG synthesis within the CNS. Radioimmunoprecipitation demonstrated IgG antibodies against HTLV-1 envelope and core proteins in all HAM/TSP CSF and sera tested. Regarding the 3 sample pairs indeterminate in EIA for intrathecal synthesis, 2 showed stronger precipitation of HTLV-1 antigens by CSF IgG than by equal amounts of serum IgG.

CONCLUSION

Intrathecal antibody synthesis specific for both HTLV-1 core and envelope antigens is common in HAM/TSP, thus providing conclusive evidence for an immune response to HTLV-1 within the CNS.

HTLV-1 and myelopathy in Salvador (northeastern Brazil): a case control study

The principal aim of the study was to determine the degree of association between cerebrospinal fluid (CSF) that is positive for HTLV-1 and myelopathy in Salvador, Brazil. From the same hospital, twenty-eight cases of myelopathy and twenty-eight cases showing no neurological disorder were studied using blind selection matched 1:1 by age and sex. The twenty-eight pairs underwent HTLV-1 serology tests. In those with a positive result, anti-HTLV-1 antibodies were investigated in the CSF. The ELISA method was used, complemented by the Western-blot test. Myelopathy was considered associated with HTLV-1 only when the CSF was positive indicating neurotropism of the virus. The mean age of the cases was 44.6 +/- 15.6 years and the control group was 43.5 +/- 16.0 (p > 0.05). An OR of 9.0 was detected with a reliability interval (95%) of 1.652-48.866 and chi-square significant at the 0.02 level. Despite a strong degree of association and considering the low level of precision, there is a need for analytical studies with larger samples which besides improving the precision will allow for greater control of the confounding variables.

Lymphocyte alveolitis in HAM/TSP patients. Preliminary report

HTLV-I associated myelopathy has been described as a systemic disease characterized by manifestations in several organs outside the nervous system. We report inflammatory pulmonary involvement in patients with diagnosis of HAM.

Differential diagnosis of HTLV-I-associated myelopathy and multiple sclerosis in Iranian patients

Two Iranian patients with chronic progressive spastic paraparesis and urinary dysfunction were referred to our hospital with the presumptive diagnosis of multiple sclerosis (MS). Routine CSF analysis and magnetic resonance imaging of the two patients were only partially characteristic of MS. Testing for antibodies to human T-cell leukemia virus type I [HTLV-I] in serum using a radioimmune precipitation assay revealed antibodies to HTLV-I in both patients. The infection with HTLV-I was confirmed by polymerase chain reaction (PCR) and liquid hybridization analysis using primers to the tax/rex region and a corresponding probe, demonstrating proviral DNA in peripheral blood mononuclear cells of both patients. On the basis of these findings demonstrating the presence of proviral HTLV-I DNA in the two Iranian patients, the initial diagnosis of MS was corrected to that of HTLV-I-associated myelopathy (HAM). In contrast, several patients with definite MS (nine from Germany, two from Iran) with a relapsing and remitting form of the disease were tested for HTLV-I infection by enzyme-linked immunosorbent assay and PCR, which yielded negative results. However, the mother of one HAM patient was found to be infected with HTLV-I. To support an association between HTLV-I infection and CNS disease in the two HAM patients, we analyzed the production of specific IgG antibodies within the CNS based on a simple enzyme immunoassay for viral IgG antibodies in CSF and serum. In the two HAM patients there was significant intrathecal antibody production directed against HTLV-I, but this was not found in any of the samples from MS patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated antibodies to synthetic peptides of HTLV-1 envelope transmembrane glycoproteins in patients with HAM/TSP

We studied the antibody response to various kinds of well-characterized synthetic peptides of human T lymphotropic virus type 1 (HTLV-1) envelope glycoproteins in patients with HTLV-1 associated myelopathy (HAM)/tropical spastic paraparesis (TSP) and non-HAM/TSP HTLV-1 carriers. The serum antibody titers to most of the synthetic peptides were significantly higher in patients with HAM/TSP than those in non-HAM/TSP HTLV-1 carriers. However, the degree of the increase of antibody titers to the synthetic peptides corresponding to the transmembrane portions of HTLV-1 envelope glycoproteins (env-p20E), such as p20E 332-352, 374-392, 426-448 and 458-488, was greater than those to synthetic peptides of exterior portions of HTLV-1 envelope glycoproteins (env-gp46) in sera from patients with HAM/TSP. Antibodies to env-p20E 332-352 and 374-392 were elevated in the cerebrospinal fluid (CSF) only from patients with HAM/TSP but not from non-HAM/TSP HTLV-1 carriers. These data indicate that the increase of antibody titers to transmembrane portions of HTLV-1 envelope glycoproteins in sera and CSF is a characteristic feature of antibody response in patients with HAM/TSP and may be closely associated with the development of HAM/TSP from non-HAM/TSP HTLV-1 carriers.

Cytotoxic and suppressor activities in patients with HTLV-I-associated myelopathy

Since there are several immune abnormalities and autoimmune-like features in human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy/HTLV-I-associated tropical spastic paraparesis (HAM/TSP), we examined cytotoxic and suppressor cell functions in HAM/TSP. In this study, we assayed cell-mediated cytotoxicity of CD8+ T-cell lines established from cerebrospinal fluid lymphocytes of two patients with HAM and concanavalin A-induced suppressor cell activities of peripheral blood lymphocytes from five patients with HAM. Our study revealed that three of four CD8+ T-cell lines showed cytotoxic activities against autologous CD4+ T-cell lines infected with HTLV-I, and two of the three lines showed major histocompatibility complex class I-restricted cytotoxicity. We also demonstrated that the concanavalin A-induced suppressor function was not defective in HAM patients. Therefore, the immune abnormalities and autoimmune-like features observed in HAM/TSP may not result from defective cytotoxic or suppressor cell activities.

Human T-cell lymphotropic virus type I sequences detected by nested polymerase chain reactions are not associated with multiple sclerosis

The hypothesis that human T-cell lymphotropic virus type I (HTLV-I) infection is associated with multiple sclerosis (MS) was tested by using primers specific to gag and pol regions of HTLV-I in an analysis that used polymerase chain reactions. No amplification of DNA from patients with MS was detected with primers for either region. After application of a more sensitive scheme with use of nested primers, however, half the samples, including patients with MS and normal control subjects, were found to contain pol DNA sequences. No sequences related to the HTLV-I gag region were detected among patients with MS by using nested primers. Sequences of the amplified HTLV-I pol genomes were determined. Regardless of their origin (MS or normal control), the pol region sequences were similar to HTLV-I sequences reported by other investigators. We conclude that HTLV-I does not have a distinct association with MS, but HTLV-I-related sequences, although in extremely low copy number, may be present in human genomes.

Presence of serum anti-human T-lymphotropic virus type I (HTLV-I) IgM antibodies means persistent active replication of HTLV-I in HTLV-I-associated myelopathy

We investigated serum IgM antibodies against human T-lymphotropic virus type I (HTLV-I) in 29 HTLV-I associated myelopathy (HAM) patients and 34 HTLV-I carriers, using western blot analysis. Anti-HTLV-I IgM was detected in all 6 post-transfusional HAM patients and in 19 of 23 (83%) HAM patients with no history of blood transfusion, but in only 4 of 21 (19%) HTLV-I carriers. In HAM patients, HTLV-I proviral DNA integrated into peripheral blood lymphocyte (PBL) was detected by Southern blot analysis in all of the 6 (100%) and 18 of the 23 (78%). In contrast, it was detected in only 2 of 25 (8%) HTLV-I carriers. For the serum anti-HTLV-I IgM and HTLV-I provirus in PBL, the differences between the HAM and HTLV-I carriers were statistically significant (P less than 0.01). Our data indicate that the increased HTLV-I proviral DNA in PBL is produced by the persistent active replication of HTLV-I in HAM. Furthermore, Southern blot analysis showed intense bands in HAM patients with histories of blood transfusion, in whom the progression of the disease had been rapid. We conclude that the persistent active replication of HTLV-I is an important factor in the pathogenesis of HAM.

Nucleotide sequence analysis of a provirus derived from an individual with tropical spastic paraparesis

Human T-cell lymphotropic virus type 1 (HTLV-1), the cause of inapparent infections and T-cell leukemias and lymphomas, has also been implicated in two chronic neurological diseases, tropical spastic paraparesis (TSP) and HTLV-1 associated myelopathy (HAM). We initiated a search for a neurotropic variant of HTLV-1 that might be responsible for these chronic progressive myelopathies by cloning and sequencing a provirus from a T-cell line from an individual with TSP. The LTRs and genes of the TSP provirus differ from HTLV-1 by 20-30 nucleotides in each region, but none of the substitutions ostensibly affect functional sites with the exception of the env gene. We document one substitution in the region encoding gp46 common to TSP and HAM proviruses and a mutation that introduces two stop codons in the region encoding gp21. The latter should delete about 100 amino acids from the transmembrane anchor, and, for this reason, the progeny of the sequenced provirus are likely to be defective viruses, maintained in the culture through coinfection of cells with wild-type non-defective HTLV-1. While defective viruses could be responsible for persistent infection of the nervous system in TSP, this cannot be generally the case as we show that HTLV-1 DNA amplified from cell lines from two other individuals with TSP lacked the stop codons. Similarly, comparisons of DNA amplified from HTLV-1 DNA in cases of ATL, HAM, and TSP did not establish a correlation between the mutation in gp46 and neurological disease. The issue of neurotropic variants in HTLV-1 associated neurological disease thus remains an open one which may be resolved in the future by examining proviruses in cells in the lesions in the nervous system; or proviruses in ATL and HAM/TSP which differ in their ability to replicate in glial or neuronal cells.

Vacuolar myelopathy in AIDS. A morphological analysis

Between 1986 and 1988 we studied the spinal cord of 40 patients dying of AIDS. Transverse and longitudinal sections from a minimum of four levels of the spinal cord were examined by means of conventional histology, immunohistochemistry and electron microscopy. Out of 22 cases there were 6 showing a mild, 11 a moderate and 5 a severe myelopathy. Among these cases with severe myelopathy, vacuolar degeneration of the posterior, lateral, and anterior columns of the white matter, which are typical findings of vacuolar myelopathy (VM), were present. Cervical and thoracic cords were affected in all cases, the lumbal cord, however, in only two. Fusiform vacuoles, 30 to 180 microns in diameter and 200 to 500 microns in length, could be seen rising between the axolemma and the myelin sheath. Most of them were still containing an axon cylinder. Foamy phagocytic cells, phagocytosing axons of apparently preserved structure were found within the vacuoles. These foamy macrophages contained rests of axons in their cytoplasm. However, only one case with severe tissue disruption exhibited myelin debris as well. Our morphological findings suggest that in VM of AIDS a process of phagocytosis directed against the axon cylinders occurs simultaneously with vacuolar degeneration of the white matter of the spinal cord. The results suggest furthermore that VM, especially its moderate form, appears to be a more frequent condition than previously assumed.