Natural antibodies to the structural core protein (p24) of the human T-cell leukemia (lymphoma) retrovirus found in sera of leukemia patients in Japan

TLR7 rs179008 (A/T) and TLR7 rs3853839 (C/G) polymorphisms are associated with variations in IFN-α levels in HTLV-1 infection

Introduction

TLR7 detects the presence of single-stranded RNA (ssRNA) viruses, including human T-lymphotropic virus 1 (HTLV-1), and triggers antiviral and inflammatory responses that are responsible for infection control. Genetic variations in the TLR7 gene may alter cytokine production and influence the course of HTLV-1 infection. In the present study, the associations of TLR7 gene polymorphisms with HTLV-1-related symptoms, receptor expression levels, IFN-α and TNF-α levels and the proviral load were investigated.

Methods

Blood samples from 159 individuals with HTLV-1 infection (66 with inflammatory diseases and 93 asymptomatic individuals) and 159 controls were collected. The genotyping of polymorphisms, TLR7 gene expression analysis and the quantification of the proviral load were performed by real-time PCR, and cytokine measurement was performed by enzyme-linked immunosorbent assay (ELISA).

Results

Carriers of the polymorphic allele for TLR7 rs179008 (A/T) had lower levels of IFN-α, while carriers of the polymorphic allele for TLR7 rs3853839 (C/G) had higher levels of TLR7 and IFN-α expression. The polymorphisms were not associated with symptoms of diseases related to HTLV-1 infection. The combination of A/G alleles for the TLR7 rs179008 (A/T) and TLR7 rs3853839 (C/G) polymorphisms was associated with increased IFN-α levels and a decreased proviral load.

Discussion

Although the polymorphisms did not influence the presence of symptoms of diseases caused by HTLV-1, carriers of the wild-type alleles for TLR7 rs179008 (A/T) and the polymorphism for TLR7 rs3853839 (C/G) appears to have a stronger antiviral response and increased infection control.

Bioprospection and Selection of Peptides by Phage Display as Novel Epitope-Based Diagnostic Probes for Serological Detection of HTLV-1 and Use in Future Vaccines

Human T-lymphotropic virus 1 (HTLV-1) is endemic worldwide and the infection results in severe diseases, including Adult T-cell Leukemia (ATL) and HTLV-1 associated myelopathy (HAM). There are some limitations of employing the present commercial serological assays for both diagnostic and epidemiological purposes in different geographical areas of the Brazil, such as the Amazon Region. Currently, methods for diagnosis are usually expensive to adapt for routine use. The aim of this work was to identify and characterize specific ligands to IgG that mimic HTLV-1 epitopes through the Phage Display technique, which could be used for diagnosis and as future vaccine candidates. Initially, IgG from 10 patients with HTLV-1 and 20 negative controls were covalently coupled to protein G-magnetic beads. After biopanning, genetic sequencing, bioinformatics analysis and Phage-ELISA were performed. The technique allowed the identification of 4 clones with HTLV-1 mimetic peptides, three aligned with gp46, A6 (SPYW), B6 (SQLP) and D7 (PLIL), and one with the protease and Tax, A8 (SPPR). Clones A6 and B6 showed higher values of accessibility, antigenicity and hydrophilicity. The reactivity of the clones evaluated by the Receiver Operating Characteristic (ROC) curve showed that the B6 clone had the highest Area Under Curve (0.83) and sensitivity and specificity values (both were 77.27 %; p < 0.001). The study showed that the Phage Display technique is effective for the identification of HTLV-1-related peptides. Clone B6 indicated to be a good marker for bioprospecting diagnostic test for HTLV-1 infection and could be used as a possible vaccine candidate for future studies.

Association of the p75NTR Ser205Leu Polymorphism with Asymptomatic HTLV-1 Infection

Genetic variations in components of the immune response seem to be an important factor that contributes to the manifestation of symptoms of some diseases related to HTLV-1 infection. Nerve growth factor (NGF) and the p75 neurotrophin receptor (p75NTR) are related to the maintenance of neurons and the activation of the immune response. In this study, we evaluated the association of the NGF -198C/T, NGF Ala35Val, and p75NTR Ser205Leu polymorphisms with HTLV-1 infection and plasma cytokine levels in 166 samples from individuals infected with HTLV-1 (59 symptomatic and 107 asymptomatic). The genotyping and quantification of the proviral load were performed by real-time PCR, and cytokine levels were measured by ELISA. The NGF -198C/T and NGF Ala35Val polymorphisms were not associated with HTLV-1 infection. The frequency of the Ser/Leu genotype of p75NTR Ser205Leu was more frequent in the control group (p = 0.0385), and the Ser/Leu genotype and allele Leu were more frequent among the asymptomatic (p < 0.05), especially with respect to the HTLV-1-associated myelopathy (HAM) group (p < 0.05). The symptomatic showed a higher proviral load and higher TNF-α and IL-10 levels (p < 0.05). Asymptomatic carriers of the Ser/Leu genotype (p = 0.0797) had lower levels of proviral load and higher levels of TNF-α (p = 0.0507). Based on the results obtained, we conclude that the p75NTR Ser205Leu polymorphism may be associated with reduced susceptibility to HTLV-1 infection, a lower risk of developing symptoms, including HAM, and better infection control.

TREX1 531C>T Polymorphism is Associated with High Proviral Load Levels in HTLV-1-Infected Persons

Human T-lymphotropic virus type 1 (HTLV-1) deregulates the immune system and cell cycle, resulting in loss of immune tolerance and disease, including HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Three prime repair exonuclease 1 (TREX1) maintains innate immune tolerance of the host and host-cell permissiveness to retroviral infections. TREX1 polymorphisms may influence the course of infection and autoimmune manifestations. The influence of TREX1 531C/T polymorphism was investigated in HTLV-1 infection and development of symptoms among 151 persons infected with HTLV-1 (32 HAM/TSP, 19 rheumatologic manifestations, two dermatitis, five more than one diagnosis, two probable HAM/TSP, and 91 asymptomatic individuals) and 100 uninfected persons in the control group. Polymorphism genotyping and proviral load quantification were performed by real-time polymerase chain reaction (PCR) and antinuclear antibodies (ANAs) were screened by an indirect immunofluorescence assay. No statistically significant difference was found in polymorphism genotype and allele frequencies between the infected and control groups. HAM/TSP patients showed higher frequency of TT genotype than asymptomatic persons (p = 0.0339). Proviral load was significantly higher among individuals with CT/TT genotypes and CC genotype carriers had lower proviral load and higher levels of proinflammatory cytokines. ANAs were present only in the HAM/TSP group. TREX1 531C>T polymorphism seems to be associated with TREX-1 regulation and HTLV-1 infection.

Silencers of HTLV-1 and HTLV-2: the pX-encoded latency-maintenance factors

Of the members of the primate T cell lymphotropic virus (PTLV) family, only the human T-cell leukemia virus type-1 (HTLV-1) causes disease in humans—as the etiological agent of adult T-cell leukemia/lymphoma (ATLL), HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and other auto-inflammatory disorders. Despite having significant genomic organizational and structural similarities, the closely related human T-cell lymphotropic virus type-2 (HTLV-2) is considered apathogenic and has been linked with benign lymphoproliferation and mild neurological symptoms in certain infected patients. The silencing of proviral gene expression and maintenance of latency are central for the establishment of persistent infections in vivo. The conserved pX sequences of HTLV-1 and HTLV-2 encode several ancillary factors which have been shown to negatively regulate proviral gene expression, while simultaneously activating host cellular proliferative and pro-survival pathways. In particular, the ORF-II proteins, HTLV-1 p30^II and HTLV-2 p28^II, suppress Tax-dependent transactivation from the viral promoter—whereas p30^II also inhibits PU.1-mediated inflammatory-signaling, differentially augments the expression of p53-regulated metabolic/pro-survival genes, and induces lymphoproliferation which could promote mitotic proviral replication. The ubiquitinated form of the HTLV-1 p13^II protein localizes to nuclear speckles and interferes with recruitment of the p300 coactivator by the viral transactivator Tax. Further, the antisense-encoded HTLV-1 HBZ and HTLV-2 APH-2 proteins and mRNAs negatively regulate Tax-dependent proviral gene expression and activate inflammatory signaling associated with enhanced T-cell lymphoproliferation. This review will summarize our current understanding of the pX latency-maintenance factors of HTLV-1 and HTLV-2 and discuss how these products may contribute to the differences in pathogenicity between the human PTLVs.

A Special Connection between γδ T Cells and Natural Antibodies?

Natural antibodies (NAbs) play an important role in early host defense, autophagy and tissue remodeling, and in immune regulation. They arise spontaneously (without specific immunization), and are already present at birth. NAbs are produced by B1 B cells, MZ B cells and other B cell types. They include all major Ig subclasses but IgM antibodies are prevalent, especially early in development. NAbs may be poly-specific, recognize particular auto-antigens, or detect neo-determinants such as those exposed during apoptosis or generated by oxidation. NAbs do not require cognate T cell help but depend on soluble mediators produced by T cells. Our recent studies suggest that γδ T cells may have a special relationship with NAbs, and play a prominent role in their regulation, in part through the fine-tuning of IL-4 levels. The spontaneously activated state of these cells likely enables their cytokine production and other functions in the absence of external stimulation. Ontogenetically, the earlier arising γδ T cells are better positioned than αβ T cells to shape the developing repertoire of NAbs. Intriguingly, ligand specificities of NAbs and γδ T cell receptors appear to be overlapping, perhaps allowing γδ cognate help for certain NAb specificities. Via NAbs, γδ T cells could exert a regulatory influence on numerous processes in health and disease.

The intricate interplay between RNA viruses and NF-κB

RNA viruses have rapidly evolving genomes which often allow cross-species transmission and frequently generate new virus variants with altered pathogenic properties. Therefore infections by RNA viruses are a major threat to human health. The infected host cell detects trace amounts of viral RNA and the last years have revealed common principles in the biochemical mechanisms leading to signal amplification that is required for mounting of a powerful antiviral response. Components of the RNA sensing and signaling machinery such as RIG-I-like proteins, MAVS and the inflammasome inducibly form large oligomers or even fibers that exhibit hallmarks of prions. Following a nucleation event triggered by detection of viral RNA, these energetically favorable and irreversible polymerization events trigger signaling cascades leading to the induction of antiviral and inflammatory responses, mediated by interferon and NF-κB pathways. Viruses have evolved sophisticated strategies to manipulate these host cell signaling pathways in order to ensure their replication. We will discuss at the examples of influenza and HTLV-1 viruses how a fascinating diversity of biochemical mechanisms is employed by viral proteins to control the NF-κB pathway at all levels.

Role of Nucleocytoplasmic RNA Transport during the Life Cycle of Retroviruses

Retroviruses have evolved mechanisms for transporting their intron-containing RNAs (including genomic and messenger RNAs, which encode virion components) from the nucleus to the cytoplasm of the infected cell. Human retroviruses, such as human immunodeficiency virus (HIV) and human T cell leukemia virus type 1 (HTLV-1), encode the regulatory proteins Rev and Rex, which form a bridge between the viral RNA and the export receptor CRM1. Recent studies show that these transport systems are not only involved in RNA export, but also in the encapsidation of genomic RNA; furthermore, they influence subsequent events in the cytoplasm, including the translation of the cognate mRNA, transport of Gag proteins to the plasma membrane, and the formation of virus particles. Moreover, the mode of interaction between the viral and cellular RNA transport machinery underlies the species-specific propagation of HIV-1 and HTLV-1, forming the basis for constructing animal models of infection. This review article discusses recent progress regarding these issues.

Discovery of ATL: an odyssey in restrospect

Forty years have passed since our initial description of peculiar cases of adult-onset leukemia with abnormal cells having multi-convoluted nuclei and T cell properties, frequent in the southern regions of Japan in the early 1970s. Retrospectively, the study of adult T cell leukemia (ATL) and the related virus HTLV-I was a forerunner for all of human retrovirology, in which AIDS and the related retrovirus HIV were identified a few years later in the 1980s. Using the anti-TAC monoclonal antibody generated by the late Takashi Uchiyama during his stay in T. A. Waldmann's laboratory in NIH Bethesda, a cDNA encoding IL-2Rα chain was cloned by our group in Kyoto and by Waldmann's group in Bethesda. Abnormal IL-2Rα chain expression and the IL-2 dependency of ATL cell lines greatly contributed to the study of leukemogenesis of ATL. A new soluble factor named ADF/ATL-derived factor was also detected in ATL cell lines. After years of study, ADF proved to be a first human counterpart of thiol-related oxido-reductase thioredoxin/TRX, which opened the field of redox regulation of cell signaling involved in a variety of diseases. Close interaction among Drs. Kimishige Ishizaka, Kiyoshi Takastuki and T. A. Waldmanns before ATL and HTLV-I study was an essential base for our initiation of ATL research with Takashi Uchiyama and many other colleagues.

Human T-lymphotropic virus type 1-induced CC chemokine ligand 22 maintains a high frequency of functional FoxP3+ regulatory T cells

We recently reported that human T-lymphotropic virus type 1 (HTLV-1) infection is accompanied by a high frequency of CD4(+)FoxP3(+) cells in the circulation. In asymptomatic carriers of HTLV-1 and in patients with HTLV-1-associated inflammatory and malignant diseases, a high FoxP3(+) cell frequency correlated with inefficient cytotoxic T cell-mediated killing of HTLV-1-infected cells. In adult T cell leukemia/lymphoma (ATLL), the FoxP3(+) population was distinct from the leukemic T cell clones. However, the cause of the increase in FoxP3(+) cell frequency in HTLV-1 infection was unknown. In this study, we report that the plasma concentration of the chemokine CCL22 is abnormally high in HTLV-1-infected subjects and that the concentration is strongly correlated with the frequency of FoxP3(+) cells, which express the CCL22 receptor CCR4. Further, we show that CCL22 is produced by cells that express the HTLV-1 transactivator protein Tax, and that the increased CCL22 enhances the migration and survival of FoxP3(+) cells in vitro. Finally, we show that FoxP3(+) cells inhibit the proliferation of ex vivo, autologous leukemic clones from patients with ATLL. We conclude that HTLV-1-induced CCL22 causes the high frequency of FoxP3(+) cells observed in HTLV-1 infection; these FoxP3(+) cells may both retard the progression of ATLL and HTLV-1-associated inflammatory diseases and contribute to the immune suppression seen in HTLV-1 infection, especially in ATLL.

FoxP3+ regulatory T cells are distinct from leukemia cells in HTLV-1-associated adult T-cell leukemia

Human T-lymphotropic virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia/lymphoma (ATLL). It has been postulated that ATLL cells might act as regulatory T cells (T(regs)) which, in common with ATLL cells, express both CD25 and FoxP3, and so contribute to the severe immune suppression typical of ATLL. We report here that the frequency of CD25(+) cells varied independently of the frequency of FoxP3(+) cells in both a cross-sectional study and in a longitudinal study of 2 patients with chronic ATLL. Furthermore, the capacity of ATLL cells to suppress proliferation of heterologous CD4(+)CD25(-) cells correlated with the frequency of CD4(+) FoxP3(+) cells but was independent of CD25 expression. Finally, the frequency of CD4(+)FoxP3(+) cells was inversely correlated with the lytic activity of HTLV-1-specific CTLs in patients with ATLL. We conclude that ATLL is not a tumor of FoxP3(+) regulatory T cells, and that a population of FoxP3(+) cells distinct from ATLL cells has regulatory functions and may impair the cell-mediated immune response to HTLV-1 in patients with ATLL.

Expression of glucose transporter 1 confers susceptibility to human T-cell leukemia virus envelope-mediated fusion

Human T-cell leukemia virus type 1 (HTLV-1) was the first human retrovirus identified and causes both adult T-cell leukemia/lymphoma and tropical spastic paraparesis/HTLV-1-associated myelopathy, among other disorders. In vitro, HTLV-1 has an extremely broad host cell tropism in that it is capable of infecting most mammalian cell types, although at the same time viral titers remain relatively low. Despite years of study, only recently has a bona fide candidate cellular receptor, glucose transporter 1 (glut-1), been identified. Although glut-1 was shown to bind specifically to the ectodomain of HTLV-1 and HTLV-2 envelope glycoproteins, which was reversible with small interfering RNA directed against glut-1, cellular susceptibility to HTLV upon expression of glut-1 was not established. Here we show that expression of glut-1 in relatively resistant MDBK cells conferred increased susceptibility to both HTLV-1- and HTLV-2-pseudotyped particles. glut-1 also markedly increased syncytium formation in MDBK cells after exposure to HTLV-1. Another assay also demonstrated HTLV-1 envelope-cell fusion in the presence of glut-1. Taken together, these results provide additional evidence that glut-1 is a receptor for HTLV.

Rat CRM1 is responsible for the poor activity of human T-cell leukemia virus type 1 Rex protein in rat cells

Rat models of human T-cell leukemia virus type 1 (HTLV-1)-related diseases such as adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis have been reported. However, these models do not completely reproduce human diseases partly because HTLV-1 replicates poorly in rats. We investigated here the possible reason for this. We found that the activity of Rex in rat cells is quite low compared to that in human cells. As Rex function depends largely on the CRM1 protein, whose human type (human CRM1 [hCRM1]) directly binds to Rex and exports it from the nucleus to the cytoplasm, we assessed whether rat CRM1 (rCRM1) could act as well as hCRM1 as a cofactor for Rex activity. We first cloned a cDNA encoding rCRM1 and found that both rCRM1 and hCRM1 could bind to and export Rex protein to the cytoplasm with similar efficiencies. However, unlike hCRM1, rCRM1 could hardly support Rex function because of its poor ability in inducing the Rex-Rex interaction required for RNA export into the cytoplasm. These observations suggest that the poor ability of rCRM1 to act as a cofactor for Rex function may be responsible for the poor replication of HTLV-1 in rats.

Viral Disease in Hematology

As part of the international outreach of the American Society of Hematology, this review addresses some aspects of the genetics, biology, epidemiology, and clinical relevance of viruses that cause a variety of hematopoietic disorders in human populations. The viruses described here have a different pattern of geographical distribution, and the disease manifestations may vary according to environmental and/or genetic characteristics of the host. Epstein-Barr virus, a linear double-stranded DNA virus (herpesvirus), and the human T-cell leukemia virus, a retrovirus with a single-stranded diploid RNA genome, are associated among other diseases with lymphoma and leukemia/lymphoma, respectively. Both viruses cause a lifelong infection, but only a small percentage of infected individuals develop hematopoietic neoplasms. Epidemiological data suggest that the time of infection may be important in determining disease outcome in both HTLV-I and EBV infection. The pathogenic mechanisms used by these viruses are of most interest since they may recapitulate growth dysregulation steps also occurring in other hematopoietic malignancies.

In Section I Dr. Franchini reviews the biology, genetics and diseases associated with HTLV-I and HTLV-II. In Section II, Dr. Ambinder reviews the biology of EBV infection and its relationship to the pathogenesis of Hodgkin's disease and other malignancies.

In Section III, Dr. Barry reviews the viral hemorrhagic fevers caused by RNA viruses such as Arenaviridae, Bunyaviridae, Filoviridae, and Flaviviridae, which can lead to acute syndromes that can be fatal. However, prompt diagnosis is key for patient management as well as for limiting their spread to others. These syndromes have become the focus of public concern and represent not only a clinical challenge, since in most cases no specific antiviral treatment is available, but also a challenge for future basic research on their biology and pathogenesis since little is known at present.

Viral Disease in Hematology

As part of the international outreach of the American Society of Hematology, this review addresses some aspects of the genetics, biology, epidemiology, and clinical relevance of viruses that cause a variety of hematopoietic disorders in human populations. The viruses described here have a different pattern of geographical distribution, and the disease manifestations may vary according to environmental and/or genetic characteristics of the host. Epstein-Barr virus, a linear double-stranded DNA virus (herpesvirus), and the human T-cell leukemia virus, a retrovirus with a single-stranded diploid RNA genome, are associated among other diseases with lymphoma and leukemia/lymphoma, respectively. Both viruses cause a lifelong infection, but only a small percentage of infected individuals develop hematopoietic neoplasms. Epidemiological data suggest that the time of infection may be important in determining disease outcome in both HTLV-I and EBV infection. The pathogenic mechanisms used by these viruses are of most interest since they may recapitulate growth dysregulation steps also occurring in other hematopoietic malignancies.

In Section I Dr. Franchini reviews the biology, genetics and diseases associated with HTLV-I and HTLV-II. In Section II, Dr. Ambinder reviews the biology of EBV infection and its relationship to the pathogenesis of Hodgkin's disease and other malignancies.

In Section III, Dr. Barry reviews the viral hemorrhagic fevers caused by RNA viruses such as Arenaviridae, Bunyaviridae, Filoviridae, and Flaviviridae, which can lead to acute syndromes that can be fatal. However, prompt diagnosis is key for patient management as well as for limiting their spread to others. These syndromes have become the focus of public concern and represent not only a clinical challenge, since in most cases no specific antiviral treatment is available, but also a challenge for future basic research on their biology and pathogenesis since little is known at present.

Altered interleukin-2 receptor alpha-chain is expressed in human T-cell leukaemia virus type-I-infected T-cell lines and human peripheral blood mononuclear cells of adult T-cell leukaemia patients through an alternative splicing mechanism

A polymerase chain reaction (PCR) method was used to detect the interleukin-2 receptor alpha-chain (IL-2R alpha) chain which lacks the conventional transmembrane (TM) domain in mRNA from human T-cell leukaemia virus type-I (HTLV-I)-infected cell lines or peripheral blood mononuclear cells (PBMC) isolated from adult T-cell leukaemia (ATL) patients. Primer pairs encompassing the TM domain were selected to generate a 357-base pair (bp) fragment. A 146-bp PCR product was observed consistently in addition to the target 357-bp PCR product in mRNA from HTLV-I-infected cell lines, such as MT-1, MT-2, MT-4 and in PBMC isolated from ATL patients. However, this 146-bp PCR product was undetectable in HTLV-I-negative cell lines. The product was also detected in PBMC from normal individuals if activated in vitro with phytohaemagglutinin but not without stimulation. DNA sequence analyses revealed that exons from 5 to 7, which define a 211-bp region containing the conventional TM domain, were deleted in the 146-bp PCR product. The C-terminal amino acid sequence starting from Gly174 of the 211-bp-deleted molecule was distinct from that of conventional IL-2R alpha as a result of an altered reading frame. We identified a 45000 MW peptide generated from IL-2R alpha mRNA through this exon skip in cell lysate of MT-1 and MT-2 by Western blot analyses using an antibody raised against the peptides specific to an altered IL-2R alpha. Our results indicate that an altered IL-2R alpha chain is expressed in HTLV-I-infected T lymphocytic cell lines and in ATL patients.

Constitutive dephosphorylation and activation of a member of the nuclear factor of activated T cells, NF-AT1, in Tax-expressing and type I human T-cell leukemia virus-infected human T cells

The tax gene product of the type I human T-cell leukemia virus (HTLV-I) transactivates interleukin-2 (IL-2) gene through activation of an enhancer termed CD28 responsive element (CD28RE). Tax activation of the CD28RE is partially mediated by a member of the nuclear factor of activated T cells, NF-AT1. We have previously shown that NF-AT1 is constitutively active in Jurkat T cells stably transfected with the Tax cDNA, although the underlying molecular mechanism and physiological relevance of this finding remain unclear. In this report, we demonstrate that the active form of NF-AT1 is also present in the nuclei of HTLV-I-transformed T cells that express the Tax protein. Interestingly, the constitutive activation of NF-AT1 in these T cells is associated with its dephosphorylation. Furthermore, the dephosphorylated NF-AT1 can be rapidly rephosphorylated when the cells are incubated with cyclosporin A, an immunosuppressant inhibiting the serine/threonine phosphatase calcineurin. These results suggest that activation of NF-AT1 in Tax-expressing and HTLV-I-transformed T cells results from its dephosphorylation, which in turn may be due to deregulation of calcineurin.

Activation of the IL-2 gene promoter by HTLV-I tax involves induction of NF-AT complexes bound to the CD28-responsive element

The tax gene product of the type I human T-cell leukemia virus (HTLV-I) is a potent transcriptional activator of various growth-related cellular genes, including that encoding interleukin-2 (IL-2). Tax activation of many of these target genes appears to be mediated by the NF-kappa B/Rel and CREB/ATF family of cellular transcription factors. However, the mechanism by which Tax transactivates the IL-2 gene remains unclear. In the present study, we demonstrate that neither NF-kappa B/Rel nor CREB/ATF is sufficient for Tax-mediated activation of the IL-2 promoter. Two novel nuclear protein complexes are induced by Tax and specifically bind to an IL-2 gene enhancer, the CD28-responsive element (CD28RE). Immunobiochemical analyses suggest that these DNA binding complexes contain at least two members of the nuclear factor of activated T cells, NF-ATp and NF-ATc. However, the CD28 binding NF-AT complexes do not contain Jun and Fos family proteins that have been proposed to serve as NF-AT partners in the activation of the IL-2 NF-AT motif. Transient transfection studies demonstrate that the in vivo expressed NF-ATp binds to the CD28RE probe and enhances Tax-mediated activation of this critical IL-2 enhancer. We demonstrate further that binding of NF-AT to CD28RE is critical for Tax activation of the IL-2 promoter. Together, these results suggest a novel mechanism of Tax-mediated activation of the IL-2 gene, which involves the induction of NF-AT-containing CD28RE binding complexes.

Time course and cytokine dependence of human T-cell lymphotropic virus type 1 T-lymphocyte transformation as revealed by a microtiter infectivity assay

Human T-cell lymphotropic virus type 1 (HTLV-1) enhances the growth of T lymphocytes, allowing the generation of T-lymphocyte cell lines. This report describes a limiting-dilution assay system which uses low input numbers of HTLV-1-producing cells for generation of T-lymphocyte cultures. The HTLV-1 transformants generated with this assay system produced high levels of HTLV-1 p24 antigen and required exogenous cytokines for maintenance. Clonal populations of CD4- or CD8-positive HTLV-1 transformants were generated with transformation efficiency rates as high as 78%. An exogenous cytokine is necessary for HTLV-1 T-lymphocyte transformation, and cytokine dependence is the most likely outcome of infection and transformation. HTLV-1 T-lymphocyte transformation can occur in the presence of cytokines other than interleukin-2 (IL-2), such as IL-4 or IL-7. IL-4- or IL-7-dependent HTLV-1 transformants underwent T-lymphocyte mitogenesis in response to their homologous cytokines but proliferated best in the presence of IL-2. Since the receptors for IL-2, IL-4, and IL-7 share the IL-2 gamma chain, this component may be the common element in the signaling pathway for HTLV-1-associated transformation.

Expression of the intestinal T-lymphocyte-associated-molecule recognized by the HML-1 antibody on mononuclear cells from HTLV-I-infected subjects

We investigated the expression of a monoclonal antibody (HML-1) defined antigen that appears on human intestinal T-lymphocytes in HTLV-I-related disease. We studied 25 ATL, and 24 healthy HTLV-I carriers. Patients with acute ATL showed a variety of the expression of the HML-1 antigen (range 0.4-74.8%). HML-1 expression on mononuclear cells (MNCs) in blood from patients with chronic ATL ranged from 1.7-43.6% (mean 13.5%). This level of expression was less than that of patients with acute ATL, but not significantly. In patients with smoldering ATL, the degree of patients with acute ATL, but not significantly. In patients with smoldering ATL, the degree of expression ranged from 1.6-13.3% (mean 8.0%). In contrast to patients with acute ATL, MNCs from patients with acute myelogenous leukemia (AML), acute lymphocytic leukemia (ALL), and B-cell type chronic lymphocytic leukemia (B-CLL) did not express the HML-1 antigen, except for the 2 patients with ALL. Healthy HTLV-I carriers and healthy controls also were negative for HML-1 reactivity. In acute ATL, patients with gastrointestinal tract infiltration tended to have high expression of the HML-1 epitope. After stimulation with phytohemagglutinin (PHA), healthy HTLV-I carriers showed significantly increased expression of the HML-1 epitope (P < 0.05). Recently, the beta 7 integrin family has been found to play a specific role in mucosal localization or adhesion, and HML-1 protein was found to match the deduced beta 7 N-terminal sequence. We propose that the cellular gene responsible for HML-1 epitope expression may, like IL-2, IL-2R, etc., be transactivated by infection with HTLV-I, and HML-1 antigen gene expression by HTLV-I infection may lead to infiltration of ATL cells with highly expressed HML-1 epitope into the gut mucosa.

Mechanisms of Tax Regulation of Human T Cell Leukemia Virus Type I Gene Expression

During the last several years, the human T cell leukemia virus type I (HTLV-I) has become recognized as an important cause for public health concern throughout the world. HTLV-I is the causative agent of a variety of clinical diseases, including an aggressive lymphoproliferative disorder named adult T cell leukemia. HTLV-I induces pathogenicity in the infected host cell through the synthesis of a virally encoded protein called Tax. Expression of Tax is critical to the life cycle of the virus, as the protein greatly increases the efficiency of HTLV-I gene transcription and replication. Furthermore, Tax has been shown to deregulate the transcription of many cellular genes, leading to the hypothesis that the presence of Tax promotes unchecked growth in the HTLV-I-infected cell. The mechanism of Tax trans-activation of HTLV-I gene expression is not known. Tax does not bind directly to the Tax-responsive promoter elements of the virus, but appears to function through interaction with certain cellular DNA binding proteins, including activating transcription factor 2 and cAMP response element binding protein that recognize these sequences. This review summarizes some of the recent work in the field aimed at elucidating the mechanism of Tax trans-activation of HTLV-I gene expression. Copyright 1995 S. Karger AG, Basel

Tax protein of human T-cell leukemia virus type I binds to the ankyrin motifs of inhibitory factor kappa B and induces nuclear translocation of transcription factor NF-kappa B proteins for transcriptional activation

Human T-cell leukemia virus type I causes adult T-cell leukemia and tropical spastic paraparesis, and its regulator protein Tax has been implicated in the pathogenic activity of human T-cell leukemia virus type I. Tax activates transcription of viral and cellular genes through specific enhancers: the 21-bp enhancer of human T-cell leukemia virus type I, the nuclear factor kappa B (NF-kappa B)-binding site of the interleukin 2 receptor alpha gene, and the serum-responsive element of c-fos. Tax binds to enhancer-binding proteins including cAMP-responsive element-binding protein, cAMP-responsive element modulator, transcription factor NF-kappa B p50 and p67SRF, and associates with each enhancer DNA indirectly. In addition to this mechanism, we report here that Tax binds to inhibitory factor kappa B gamma (I-kappa B) gamma, which forms a complex with NF-kappa B protein heterodimer p50-p65 or homodimer p50-p50 and retains them in the cytoplasm. Tax binding to I-kappa B gamma induces nuclear translocation of NF-kappa B p65. In association with this nuclear translocation of p65, transcription directed by the kappa B enhancer is strongly activated. Tax binds to the ankyrin motifs of I-kappa B gamma, suggesting its possible interaction with many other proteins carrying ankyrin motifs contributing to various regulatory processes. This is a different mechanism of transcriptional activation by the oncoprotein Tax and seems to be independent from the trans-activation through indirect binding to enhancer DNAs.

The trans-activator tax of human T-cell leukemia virus type 1 (HTLV-1) interacts with cAMP-responsive element (CRE) binding and CRE modulator proteins that bind to the 21-base-pair enhancer of HTLV-1

The trans-activator protein Tax of human T-cell leukemia virus type 1 (HTLV-1) activates the viral 21-base-pair (bp) enhancer in the long terminal repeat and has been suggested to associate indirectly with the enhancer DNA. To demonstrate this, we used DNA-affinity precipitation assay and detected the Tax protein in 21-bp DNA-protein complexes isolated from HTLV-1-infected cells. To identify cellular components in the complexes, we tested various 21-bp DNA-binding proteins by gel electrophoretic mobility-shift assay. Each binding protein gave a shifted band of each 21-bp DNA-protein complex, and exogenously added Tax protein further shifted these bands of cAMP-responsive element (CRE) binding protein (CREB) and CRE modulator but did not shift other bands. Anti-Tax antibodies blocked formation of the complex, indicating complex formations of [Tax-CREB(or CRE modulator)-21-bp DNA]. The formations of these complexes paralleled the functional activities of Tax mutants. Furthermore, the Tax-CREB complex was detected in a nuclear extract of HTLV-1-infected cells, and the Tax-CREB-21-bp-DNA complex was demonstrated as a major component of Tax complexes containing the 21-bp DNA probe. These observations indicate that Tax protein binds to CREB and CRE modulator and the complexes then bind to the 21-bp enhancer, suggesting that the complex binding to the enhancer mediates trans-activation of transcription.

Ablation of transplanted HTLV-I Tax-transformed tumors in mice by antisense inhibition of NF-kappa B

Mice transgenic for the human T cell leukemia virus (HTLV-I) Tax gene develop fibroblastic tumors that express NF-kappa B-inducible early genes. In vitro inhibition of NF-kappa B expression by antisense oligodeoxynucleotides (ODNs) inhibited growth of these culture-adapted Tax-transformed fibroblasts as well as an HTLV-I-transformed human lymphocyte line. In contrast, antisense inhibition of Tax itself had no apparent effect on cell growth. Mice treated with antisense to NF-kappa B ODNs showed rapid regression of transplanted fibrosarcomas. This suggests that NF-kappa B expression may be necessary for the maintenance of the malignant phenotype and provides a therapeutic approach for HTLV-I-associated disease.

In vitro activation of transcription by the human T-cell leukemia virus type I Tax protein

The human T-cell leukemia virus type I (HTLV-I) regulatory protein Tax activates transcription of the proviral long terminal repeats and a number of cellular promoters. We have developed an in vitro system to characterize the mechanism by which Tax interacts with the host cell transcription machinery. Tax was purified from cells infected with a baculovirus expression vector. Addition of these Tax preparations to nuclear extracts from uninfected human T lymphocytes activated transcription of the HTLV-I long terminal repeat approximately 10-fold. Transcription-stimulatory activity copurified with the immunoreactive 40-kDa Tax polypeptide on gel filtration chromatography, and, as expected, the effect of recombinant Tax was diminished in HTLV-I-infected T-lymphocyte extracts containing endogenous Tax. Tax-mediated transactivation in vivo has been previously shown to require 21-bp-repeat Tax-responsive elements (TxREs) in the promoter DNA. Stimulation of transcription in vitro was also strongly dependent on these sequences. To investigate the mechanism of Tax transactivation, cellular proteins that bind the 21-bp-repeat TxREs were prepared by DNA affinity chromatography. Recombinant Tax markedly increased the formation of a specific host protein-DNA complex detected in an electrophoretic mobility shift assay. These data suggest that Tax activates transcription through a direct interaction with cellular proteins that bind to the 21-bp-repeat TxREs.

In vitro activation of transcription by the human T-cell leukemia virus type I Tax protein

The human T-cell leukemia virus type I (HTLV-I) regulatory protein Tax activates transcription of the proviral long terminal repeats and a number of cellular promoters. We have developed an in vitro system to characterize the mechanism by which Tax interacts with the host cell transcription machinery. Tax was purified from cells infected with a baculovirus expression vector. Addition of these Tax preparations to nuclear extracts from uninfected human T lymphocytes activated transcription of the HTLV-I long terminal repeat approximately 10-fold. Transcription-stimulatory activity copurified with the immunoreactive 40-kDa Tax polypeptide on gel filtration chromatography, and, as expected, the effect of recombinant Tax was diminished in HTLV-I-infected T-lymphocyte extracts containing endogenous Tax. Tax-mediated transactivation in vivo has been previously shown to require 21-bp-repeat Tax-responsive elements (TxREs) in the promoter DNA. Stimulation of transcription in vitro was also strongly dependent on these sequences. To investigate the mechanism of Tax transactivation, cellular proteins that bind the 21-bp-repeat TxREs were prepared by DNA affinity chromatography. Recombinant Tax markedly increased the formation of a specific host protein-DNA complex detected in an electrophoretic mobility shift assay. These data suggest that Tax activates transcription through a direct interaction with cellular proteins that bind to the 21-bp-repeat TxREs.

Application of screening and confirmatory assays for anti-HTLV-I/II in U.K. populations

During an epidemiological study of a low risk U.K. population diverse screening and confirmatory assays for the detection of anti-HTLV-I/II were assessed. Sera from 2,900 antenatal patients were tested for anti-HTLV-I/II by gelatin particle agglutination assay (GPA). All reactive sera, and 133 randomly selected unreactive sera, were further tested by Abbott and DuPont ELISAs, "in house" competitive and IgG capture radioimmunoassays (RIAs), and Western blot (WB). Sera which reacted with any HTLV-I proteins by WB were tested by radio immunoprecipitation assays (RIPA). The two ELISAs detected all the GPA reactive specimens that were subsequently confirmed as anti-HTLV-I/II positive. Confirmation of positive screening results required the use of both WB and RIPA. Serological diagnosis of HTLV infection involves access to specialised assays that are not commercially available.

Lack of detectable human T-cell lymphotropic virus type I sequences in samples from multiple sclerosis patients

Recently, inconclusive results have followed the early data on the possible association between multiple sclerosis (MS) and human T-cell lymphotropic virus type I (HTLV-I) infection. For this reason, we examined this hypothesis using the polymerase chain reaction (PCR) to study samples of differing origin from Italian MS patients. In particular, we developed a systematic analysis of paraffin-embedded brain white matter from histologically defined lesions of 14 MS patients using PCR and primer sets specific for HTLV-I sequences; additionally, cerebrospinal fluids (CSFs) from 12 patients and peripheral blood mononuclear cells (PBMCs) from subjects at the early and late phase of the disease were investigated for free HTLV-I virions and specific proviral sequences, respectively. In agreement with some groups who reported lack of HTLV-I sequences in PBMCs of MS patients but in clear contrast with others, we failed to detect specific viral sequences using this broad approach.

Complex formation of human T-cell leukemia virus type I p40tax transactivator with cellular polypeptides

We examined cellular components which associate with p40tax, the viral transactivation molecule of human T-cell leukemia virus type I. Such molecules were searched by immunoprecipitation with polyclonal and monoclonal antibodies specific for p40tax. Two cellular proteins with molecular masses of 95 kDa (p95) and 60 kDa (p60) were specifically coprecipitated with p40tax from extracts of all p40tax-producing cell lines but not from p40tax-negative cell lines. The p60 component was also shown to associate with p40tax in vitro, by using radiolabel-chase experiments. Rabbit antisera specific for p60 and p95 were prepared by immunization with electrophoretically purified molecules. While anti-p95 antiserum coprecipitated p40tax, no p40tax could be identified in immunoprecipitates by using a polyclonal anti-p60 antiserum. The partial amino acid sequence of p60 demonstrated that p60 is identical to the human 60-kDa heat shock protein (a member of the chaperonin family of proteins). Although the biological significance of the complex formation of p40tax with p95 and p60 has yet to be determined, it may be that the complex formation is one of the mechanisms by which the biological activity of p40tax can be regulated.

Linear antigenic regions of the structural proteins of human T-cell lymphotropic virus type I detected by enzyme-linked immunosorbent assays using synthetic peptides as antigens

We synthesized 46 sequential peptides 21 to 39 amino acids long over the structural protein of human T-cell leukemia virus type I (HTLV-I; the p19 and p24 gag protein and the gp46 and p20E env proteins) and tested their reactivities against antibodies in sera from HTLV-I healthy carriers and patients diagnosed as having human T-cell leukemia-lymphoma (ATLL) and myelopathy (HAM) by using an enzyme-linked immunosorbent assay. Of the 46 synthetic peptides, 18 peptides (2 corresponding to the p19 gag protein, 2 corresponding to the p24 gag protein, 8 corresponding to the gp46 env protein, and 6 corresponding to the p20E env protein) reacted with antibodies in the sera from HTLV-I healthy carriers. In particular, the peptides comprising amino acids 100 to 119 and 119 to 130 of the gag and 175 to 199, 213 to 236, 253 to 282, and 288 to 317 of the env proteins reacted with antibodies in sera from more than 30% of HTLV-I healthy carriers. These peptides also showed high reactivities to the antibodies in the sera from patients with ATLL and HAM. The results indicate that the predominant antigenic regions of the structural protein of HTLV-I were located at the C-terminal end of the p19 gag protein and the C-terminal half of the gp46 env protein, and the corresponding peptides proved to be useful antigens in detecting antibodies in the sera from individuals infected with HTLV-I.

Transgenic thymocytes are refractory to transformation by the human T-cell leukemia virus type I tax gene

Previous transgenic work demonstrated transforming activity of the human T-cell leukemia virus type I Tax protein in fibroblasts. In the present study, a Thy-1-based vector was used to express Tax in thymocytes. These mice developed no functional or neoplastic abnormalities of T cells but developed fibroblastic tumors with a longer latency than in the previous model.

HTLV-I infection in French West Indies: a case-control study

A case-control study was performed in Martinique, French West Indies, comparing 66 anti-p24 antibody carriers to 91 seronegative subjects for HTLV-I, matched for age and place of residence. The aim of our study was to identify factors associated with HTLV-I infection and to observe whether clinical examination and biological measurements would reveal any abnormalities among the seropositive subjects. We observed a predominance of females among seropositive subjects (74% compared to 59%, p less than 0.05), and a greater risk due to earlier blood transfusions (p less than 0.001). This survey revealed important differences between cases and controls regarding socioeconomic factors: cases had fewer luxuries or advantages (i.e. bathroom, toilets, refrigerator, telephone, p less than 0.01), were more corpulent (p less than 0.05), and more often widowed, divorced or separated (p less than 0.01) than the controls. Although the differences were not significant, the seropositive donors seemed to be less educated, and were from a lower socioprofessional class than the seronegative donors. With regard to clinical symptoms (infections, adenopathies, splenomegaly, hepatomegaly) and biological parameters (blood count; T-cell subsets, electrophoresis of protids, immunoglobulins, calcemia, antischistosomal antibody), seropositive subjects appeared to be healthy; no parameters, except for alpha 1 globulin (p less than 0.05) and monocytes (p less than 0.05), were found to be correlated with seropositivity; but these two parameters remained within their normal ranges. This study confirms blood transfusion as a risk factor. It underscored the importance of socioeconomic factors for seropositivity.

Human T-cell leukemia-lymphoma virus type I (HTLV-I) expression in fresh peripheral blood mononuclear cells from patients with tropical spastic paraparesis/HTLV-I-associated myelopathy

Tropical spastic paraparesis/human T-cell leukemia-lymphoma virus type I (HTLV-I)-associated myelopathy (TSP/HAM) is a chronic neurological illness epidemiologically associated with HTLV-I infection. We investigated the role of HTLV-I in the pathogenesis of this disease by studying viral expression in fresh uncultured peripheral blood mononuclear cells (PBMCs) of six patients of Caribbean origin with TSP/HAM. The PBMC genomic DNA of all the patients studied carried HTLV-I provirus, but viral expression was not detected by Northern (RNA) blot analysis of total cellular PBMC RNA. When the reverse transcriptase polymerase chain reaction technique was used with primers specific for the tax-rex mRNA, all of the samples were positive for this viral mRNA species, regardless of the duration of the illness (range, 2 to 13 years). The splice junctions for the tax-rex mRNA described in cases of HTLV-I-induced adult T-cell leukemia (position 5183 of the envelope and position 7302 of the pX region) were identical in three TSP/HAM cases studied. To ascertain whether viral expression occurred at a low level in many cells or at a high level in a few permissive cells, we performed in situ hybridization on fresh PBMCs from two patients (2 and 7 years after clinical diagnosis), seeking HTLV-I RNA sequences. Our finding indicated that in vivo HTLV-I expression occurred at a high level in a few cells (1 of every 5,000 PBMCs) in both cases studied. The fact that cells of all six patients with TSP/HAM were positive for viral expression, regardless of the time lag from diagnosis, suggests that persistent expression of a viral product(s) may be pivotal in the pathogenesis of TSP/HAM.

A 36-kilodalton cellular transcription factor mediates an indirect interaction of human T-cell leukemia/lymphoma virus type I TAX1 with a responsive element in the viral long terminal repeat

The human T-cell leukemia/lymphoma virus type I (HTLV-I) trans activator, TAX1, interacts indirectly with a TAX1-responsive element, TRE-2, located at positions -117 to -163 in the viral long terminal repeat. This report describes the characterization of a 36-kilodalton (kDa) protein identified in HeLa nuclear extract which mediates the interaction of TAX1 with TRE-2. Purification of the protein was achieved by zinc chelate chromatography and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The renatured 36-kDa protein bound specifically to a TRE-2 oligonucleotide but not to nonfunctional base substitution mutant probes in a gel retardation assay. Renatured proteins of differing molecular weights were unable to form this complex. In addition, the 36-kDa protein specifically activated transcription from the HTLV-I promoter in vitro. Purified TAX1 protein formed a complex with the TRE-2 oligonucleotide in the presence of the 36-kDa protein, suggesting that indirect interaction of TAX1 with the viral long terminal repeat may be one of the mechanisms by which HTLV-I transcription is regulated.

A 36-kilodalton cellular transcription factor mediates an indirect interaction of human T-cell leukemia/lymphoma virus type I TAX1 with a responsive element in the viral long terminal repeat

The human T-cell leukemia/lymphoma virus type I (HTLV-I) trans activator, TAX1, interacts indirectly with a TAX1-responsive element, TRE-2, located at positions -117 to -163 in the viral long terminal repeat. This report describes the characterization of a 36-kilodalton (kDa) protein identified in HeLa nuclear extract which mediates the interaction of TAX1 with TRE-2. Purification of the protein was achieved by zinc chelate chromatography and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The renatured 36-kDa protein bound specifically to a TRE-2 oligonucleotide but not to nonfunctional base substitution mutant probes in a gel retardation assay. Renatured proteins of differing molecular weights were unable to form this complex. In addition, the 36-kDa protein specifically activated transcription from the HTLV-I promoter in vitro. Purified TAX1 protein formed a complex with the TRE-2 oligonucleotide in the presence of the 36-kDa protein, suggesting that indirect interaction of TAX1 with the viral long terminal repeat may be one of the mechanisms by which HTLV-I transcription is regulated.

Familial adult T-cell leukemia/lymphoma

Clinical and laboratory data are described for two siblings who both developed adult T-cell leukemia/lymphoma resulting from infection by human T lymphotropic virus type I (HTLV-I). These findings suggest that genetic factors or virus-specific factors may determine which HTLV-I-infected individuals will develop leukemia.

HTLV-I/II seropositivity and death from AIDS among HIV-1 seropositive intravenous drug users

In a prospective study of street-recruited intravenous drug users (IVDUs) in Miami, Florida, USA, 107 (46.5%) of 230 IVDUs were infected with HIV-1. Of these HIV-1 seropositive individuals, 23 were also infected with human T-lymphotropic virus type I or II (HTLV-I/II). To test the hypothesis that HTLV-I/II infection has an effect on the survival of HIV-1 seropositive IVDUs, various baseline clinical and laboratory HIV-1 related indices in HTLV-I/II positive and negative groups were compared. Life table analysis and Cox's proportional hazards model were used to estimate the potential effect of HTLV-I/II infection on the survival patterns of people infected with HIV-1. IVDUs infected with both viruses were three times more likely to die from AIDS during follow-up than were those infected with HIV-1 only. This finding suggests that HTLV-I/II seropositivity may adversely affect the clinical outcome of HIV-1 seropositive patients.

Human T-cell lymphotropic virus type I (HTLV-I) antibodies in pre-diagnostic serum of patients with familial adult T-cell leukemia/lymphoma (ATL)

In a study of 7498 American men of Japanese ancestry in Hawaii, 26 incident cases of leukemia or non-Hodgkin's lymphoma were identified after a follow-up period of 19 years. Two of the cases, who were brothers, were diagnosed with adult T-cell leukemia/lymphoma (ATL). Both of these brothers had human T-cell lymphotropic virus type I (HTLV-I) antibodies in their stored serum which were obtained 4 and 18 years before diagnosis. None of the 24 patients with other hematologic malignancies or the 26 matched controls were HTLV-I antibody positive. This finding lends further support for a role of HTLV-I in the etiology of adult T-cell leukemia/lymphoma.

Oncogenic transformation by the tax gene of human T-cell leukemia virus type I in vitro

Human T-cell leukemia virus type I (HTLV-I) is a causative agent of adult T-cell leukemia (ATL). To elucidate the role of HTLV-I in leukemogenesis, we examined the biological activity of a defective HTLV-I provirus with the env-pX 3' long terminal repeat region cloned from leukemic cells of an ATL patient. Transfection experiments showed growth stimulation of NIH 3T3 cells--growing beyond the saturation density and growing in soft agar. Since the pX sequence is known to encode three proteins, Tax, Rex, and p21x, the biological activity of each pX gene was examined separately. The growth-stimulating activity was induced only by the tax gene in NIH 3T3 cells and Rat-1 cells. Furthermore, the tax gene induced tumorigenicity in nude mice when introduced into Rat-1 cells. Thus, a transcriptional transactivator gene of HTLV-I, tax, is clearly identified as a viral oncogene without a cellular homolog. The transforming activity of tax, possibly via a transcriptional deregulation of cell growth control, may play an important role in leukemogenesis of ATL in addition to its aberrant stimulation of the interleukin 2 system.

Degeneration of oxidative muscle fibers in HTLV-1 tax transgenic mice

The HTLV-1 tax gene under control of the HTLV-1 long terminal repeat (LTR) was introduced into transgenic mice. Previously tax protein expression in the muscle and peripheral nerves of three independent mouse lines was reported. Here the localization of this transgenic protein at a cellular and subcellular level is described. Tax protein was expressed in oxidative muscle fibers that developed severe progressive atrophy. It localized to the cytoplasma where it was associated with structures resembling degenerating Z bands. This pattern of muscle fiber involvement is similar to that observed in human retroviral associated myopathy. This transgenic mouse model suggests that preferential expression of the HTLV-1 viral promoter in oxidative muscle fibers may explain the productive infection of these fibers in HTLV-1 myopathy.

No evidence of HTLV-1 infection in Japanese multiple sclerosis patients in polymerase chain reaction

To test possible association of human T cell leukemia virus type 1 (HTLV-1) with multiple sclerosis (MS), polymerase chain reaction was applied to detect HTLV-1 DNA integrated into peripheral blood mononuclear cell DNA. Nine Japanese MS patients all gave a negative result, indicating no HTLV-1 infection in these MS patients.