Human T-lymphotrophic Virus Type I Research Articles

Human T-Lymphotrophic Virus Type-I: A Unique Association with Myelopathy in Sjögren's Syndrome.

Alexandria Voigt1 and Cuong Q Nguyen1,2* 1Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, 2015 SW 16th Ave, Gainesville Florida, USA 2Center for Orphan Autoimmune Disorders, University of Florida College of Dentistry, 1600 SW Archer Rd, Gainesville, Florida, USA *Corresponding author: Cuong Q. Nguyen, PhD, Department of Infectious Diseases and Pathology, PO Box 110880, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611-0880 USA, Tel: 352-294-4180; Fax: 352-392-9704; E-mail: Nguyenc@ufl.edu

Neuroimmunity of HTLV-I Infection

Human T-lymphotrophic virus type I (HTLV-I) is an oncogenic retrovirus and its infection is associated with a variety of human diseases including HTLV-I-associated myelopathy/tropic spastic paraparesis (HAM/TSP). Large numbers of epidemiological, virological, immunological, and clinical studies on HTLV-I- and HTLV-I-associated diseases have been published, although the pathogenesis of HAM/TSP remains to be fully understood. In the last several years, researchers have shown that several key factors are important in HTLV-I-associated neurologic disease including high HTLV-I proviral load and a strong immune response to HTLV-I. Here, we review pathophysiological findings on HAM/TSP and focus on viral-host immune responses to the virus in HTLV-I infected individuals. In particular, the role of HTLV-I-specific CD8+ T cell response is highlighted.

Abstract 4524: Targeting Bcl-2 family proteins in adult T-cell leukemia/lymphoma: in vitro and in vivo effects of a novel Bcl-2 family inhibitor, ABT-737

Abstract Adult T-cell lymphoma/leukemia (ATLL) is a T-cell malignancy caused by the human T-lymphotrophic virus type I (HTLV-I), and its therapeutic outcome still remains extremely poor. Therefore, novel therapeutic strategies are needed to improve treatment outcomes. In this study, we elucidated the therapeutic potential of targeting the anti-apoptotic Bcl-2 family proteins for the treatment of ATLL using ABT-737 (Abbott Laboratories, Abbott Park, IL, USA), a small molecule inhibitor of Bcl-2, Bcl-XL and Bcl-w. We first validated the rationale of this study by immunohistochemically assessing the expression of Bcl-2 family proteins in 25 lymph-node specimens derived from ATLL patients. The Bcl-2 and/or Bcl-XL proteins were expressed in 80% of specimens. We next examined the cytotoxicity of ABT-737 against three ATLL cell lines by the Colorimetric method. ABT-737 significantly inhibited growth of MT-1, MT-2 and HuT 102 cells with concentrations of 50 percent inhibition of 2.4, 0.23 and 0.008μM at 72 h, respectively. We then tried to clarify the mechanism of growth inhibition induced with ABT-737 using MT-1 and MT-2 cells. ABT-737 induced apoptosis in both cells with cleavage of caspases 9 and 3, and PARP. ABT-737 also induced apoptosis in fresh tumor cells derived from patients with ATLL. We also tested if ABT-737 enhances the cytotoxicity induced by conventional chemotherapeutic agents or novel agents. The interactions between them were evaluated using the Chou-Talalay method. ABT-737 synergistically enhanced the cytotoxicity and apoptosis induced by doxorubicin, vincristine or etoposide and bortezomib or suberolyanilide hydroxamic acid, which are current key drugs and promising candidates for the treatment of ATLL, respectively. Finally, we investigated the growth inhibition of ABT-737 in ATLL-xenografted mice. The mean tumor volume and weight, and mean serum level of soluble interleukin-2 receptor α at day 21 of the treated mice with ABT-737 (100mg/kg/day) were significantly lower than those of vehicle-treated mice. Moreover, massive induction of apoptosis was observed in tumors treated with ABT-737 by the TUNEL assay. These results suggest that the use of ABT-737, either alone, or in combination with other conventional cytotoxic and novel drugs, represents a promising novel targeted approach to overcome drug resistance and to improve patient outcome in ATLL. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4524.

Targeting Bcl-2 Family Proteins in Adult T-Cell Leukemia/Lymphoma: In Vitro and In Vivo Effects of a Novel Bcl-2 Family Inhibitor ABT-737.

Abstract 1685Poster Board I-711Adult T-cell lymphoma/leukemia (ATLL) is a T-cell malignancy caused by human T-lymphotrophic virus type I (HTLV-I), and its therapeutic outcome is still remains very poor. Therefore, novel therapeutic strategies are needed to improve patient outcome. In this study, we elucidated the therapeutic potential to target anti-apoptotic Bcl-2 family proteins for the treatment of ATLL by using ABT-737 (Abbott Laboratories, Abbott Park, IL, USA), a small molecule inhibitor of Bcl-2, Bcl-XL and Bcl-w. We first validated the rationale of this study by assessing the expression of Bcl-2 family proteins among 25 lymph-node specimens derived from ATLL patients by using immunohistochemistory. Both or either of Bcl-2 and Bcl-XL proteins was highly expressed in 80% of specimens. We next examined the cytotoxicity of ABT-737 against ATLL cell lines. ABT-737 significantly inhibited growth of MT-1, MT-2 and HuT 102 cells with a concentration of 50 percent inhibition (IC50) at 72 h of 2.4, 0.23 and 0.008μM, respectively. We then elucidated the mechanism of growth inhibition induced by ABT-737 using MT-1 and MT-2 cells. ABT-737 induced apoptosis in MT-1, MT-2 cells with cleavage of caspase 9, 3 and PARP. ABT-737 also induced apoptosis in fresh tumor cells derived from patients with ATLL. We next elucidated the potential of ABT-737 to enhance the cytotoxicity induced by conventional chemotherapeutic agents. The interaction between them was evaluated using the Chou-Talalay method by determining the combination index. ABT-737 synergistically enhanced the cytotoxicity and apoptosis induced by either of doxorubicin, vincristine or etoposide, which is a current key drug to treat ATLL. Most importantly, ABT-737 significantly inhibited tumor growth of in vivo ATLL model using SCID mice inoculated by HuT 102 cells subcutaneously. The mean tumor volume, weight and serum level of soluble interleukin-2 receptor á of ABT-737 (100mg/kg/day)-treated mice were significantly lower than those of vehicle-treated mice after treatment for 21 days. Moreover, massive induction of apoptosis in tumors treated by ABT-737 was observed by immunofluorescent TUNEL assay. These results suggest that ABT-737 used either alone or in combination with conventional cytotoxic drugs, represents a promising novel targeted approach to overcome drug resistance and improve patient outcome in ATLL. DisclosuresNo relevant conflicts of interest to declare.

Cryptococcal pleuritis developing in a patient on regular hemodialysis

A 64-year-old male on regular hemodialysis who was a human T lymphotrophic virus Type I (HTLV-I) carrier developed cryptococcal pleuritis. The initial manifestations of the present case were a persistent cough and the accumulation of unilateral pleural effusion. A culture of the pleural fluid of the patient grew cryptococcus neoformans and a test for antigens against cryptococcus neoformans in the pleural fluid was also positive, therefore, cryptococcal pleuritis was diagnosed. Pleural cryptococcosis per se is rare and it is extremely rare for a dialysis patient to develop pleural cryptococcosis. To our knowledge, only a few cases of cryptococcal pleuritis have so far been reported in patients on dialysis. Furthermore, an isolated occurrence of cryptococcal pleuritis with no cryptococcal pulmonary parenchymal lesions, as was seen in the present case, is rare because cryptococcal pleuritis is usually associated with underlying cryptococcal pulmonary parenchymal lesions. Patients on chronic dialysis are susceptible to developing pleural effusion from many etiologies such as congestive heart failure, infection (tuberculosis, bacterial, viral, parasitic, fungal), collagen vascular disease, drug reaction, metastasis, or uremia itself. Cryptococcal pleuritis developing in a dialysis patient is extremely rare, but physicians should consider cryptococcal infection as a possible cause when pleural effusion develops in a dialysis patient and no other cause is identified, as occurred in the present case.

Chronic progressive cervical myelopathy with HTLV-I infection

To investigate the role of human T-lymphotrophic virus type I (HTLV-I) infection in four patients who developed slowly progressive myelopathy with abnormal MRI lesions in the cervical cord levels. Clinical and neuroradiologic examinations were performed, and the odds that an HTLV-I-infected individual of specified genotype, age, and provirus load had HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP) were calculated. Anti-HTLV-I antibodies were positive in both the serum and the CSF in all of the patients. Biopsied sample from spinal cord lesions showed inflammatory changes in Patient 1. Patient 2 had a demyelinating type of sensorimotor polyneuropathy. Two of the three patients examined showed high risk of developing HAM/TSP in virologic and immunologic aspects. These four cases may belong to a variant form of HAM/TSP, predominantly involving the cervical cord levels.

Influence of human T lymphotrophic virus type I on cryptogenic fibrosing alveolitis - HTLV-I associated fibrosing alveolitis: proposal of a new clinical entity.

Human T lymphotrophic virus type-I (HTLV-I), a human retrovirus, infects CD4+ lymphocytes and is thought to modify their function; a possible association with pulmonary diseases has also been suggested. However, little is known about the influence of HTLV-I on cryptogenic fibrosing alveolitis (CFA), a chronic inflammatory interstitial lung disease of unknown aetiology. In order to clarify the influence of HTLV-I infection on CFA, 72 CFA patients with and without HTLV-I infection were examined. HTLV-I positive CFA patients were likely to have larger affected areas and to show traction bronchiectasis with honeycombing change. An imbalance of matrix metalloproteinases and tissue inhibitor of metalloproteinases were also observed in the BALF of HTLV-I positive CFA patients. CD3+/CD25+ lymphocyte percentage was significantly higher in the BALF of HTLV-I positive patients compared to negative patients. MIP-1alpha, IP-10 and sICAM levels in BALF were also significantly higher in HTLV-I positive patients than in negative patients. The levels of MCP-1 and IL-8 were not significantly different. In HTLV-I positive patients, the MIP-1alpha and IP-10 levels showed a significant positive correlation with percentage of CD3+/CD25 lymphocytes. HTLV-I positive CFA patients showed a larger lesion than negative patients and exhibited increased levels of certain cytokines that correlated with activated T cells in the BALF. We suggest that HTLV-I infection may contribute to the development of CFA via activation of T cells. We also propose that these features should be taken into consideration in the treatment of CFA in HTLV-I infected individuals.

Clinical investigation of pulmonary Mycobacterium avium complex infection in human T lymphotrophic virus type I carriers.

Little is known about pulmonary Mycobacterium avium complex (MAC) infection in human T lymphotrophic virus type I (HTLV-I) carriers. A study was undertaken to investigate and clarify the characteristics of pulmonary MAC infection in these subjects. Twenty nine patients with pulmonary MAC infection without any underlying pulmonary disorder were investigated. The clinical features and radiographic appearance of HTLV-I carriers and non-carriers were compared and the bronchoalveolar lavage (BAL) fluid of these 29 patients and eight normal female control subjects was analysed. The prevalence of the HTLV-I carrier state in patients with pulmonary MAC infection was 34.5% (10/29) compared with 16.7% (529/3169) among all patients admitted to our department between 1994 and 1998 (odds ratio (OR) 2.63, 95% confidence interval (CI) 1.21 to 5.68). The HTLV-I carriers were all women and all had clinical symptoms, but they did not show systemic dissemination. Peripheral multifocal bronchiectasis with nodular shadowing was seen frequently on the chest computed tomographic (CT) scans of HTLV-I carriers. The area of the pulmonary lesions was more extensive than in non-carriers (p<0.05). White blood cell (WBC) counts and C reactive protein (CRP) levels on admission were significantly lower in HTLV-I carriers than in non-carriers (WBC: difference (D) = 1565/microl, 95% CI -68.9 to 3198.4/microl; CRP: D = 1.8 mg/dl, 95% CI -0.35 to 3.89 mg/dl). The concentrations of neutrophil elastase (NE) and interleukin (IL)-8 in BAL fluid were significantly higher in HTLV-I carriers than in non-carriers (NE: D = 1342 microg/l, 95% CI 704 to 1980.3 microg/l; IL-8: D = 304.5 pg/ml, 95% CI 89.7 to 519. 4 pg/ml). Pulmonary MAC infection causes more diffuse and widespread lesions in HTLV-I carriers than in non-carriers.

Low prevalence of flower cells in U.S.A. blood donors infected with human T-lymphotrophic virus types I and II.

Large lymphocytes with basophilic cytoplasm and cleaved/cerebriform nuclei called flower cells have been described in human T-lymphotrophic virus type I (HTLV-I) seropositive individuals and may be precursors of adult T-cell leukaemia (ATL). A cohort of 546 HTLV-seropositive former blood donors, 32 HTLV-positive sexual partners of these donors and 799 HTLV-seronegative controls has been followed as part of the Retrovirus Epidemiology Donor Study. A novel methodology was developed to systematically review peripheral blood slides from these subjects for HTLV-related lymphocyte abnormalities, using an algorithm based on morphologic features to objectively identify flower cells. The algorithm included: absence of azurophil granules; nuclear chromatin condensation; cell size >1.5 small lymphocytes; nuclear to cytoplasmic ratio >80%; and presence of nuclear folding/lobulation. Peripheral slides from subjects were screened by a medical technologist blinded to HTLV status. 6.8% of HTLV-I subjects (P = 0.0001 versus seronegatives), 0.9% of HTLV-II subjects and 1.1% of seronegatives were confirmed to have cells classified as flower cells by two haematologists using objective criteria, and blinded to serostatus. Despite the higher prevalence of flower cells in HTLV-I positives, no clinical correlations were found. Longitudinal follow-up may yield higher rates of cellular abnormalities as the sequelae of HTLV infection develop.

Clonal HTLV-I-infected CD4+ T-lymphocytes and non-clonal non-HTLV-I-infected giant cells in incipient ATLL with Hodgkin-like histologic features.

Lymph nodes from the incipient or early neoplastic phase of adult T-cell leukemia/lymphoma (ATLL) histologically resemble Hodgkin's disease. Integrated proviral human T-lymphotrophic virus type I (HTLV-I) has been demonstrated in such lesions. We studied 18 patients with this disease, and about half of the cases developed typical ATLL within 2 or 3 years. In all cases, either mono- or oligoclonal cell populations with proviral HTLV-I DNA were detected by Southern blot analysis and/or inverse polymerase chain reaction (IPCR). In addition, either a mono- or oligoclonal rearrangement of T-cell receptor genes was demonstrated. Giant cells with Reed-Sternberg-like histological features revealed CD15 and CD30 positivity. The background infiltrating lymphocytes represented either no or only minimal nuclear abnormalities with a CD4+ T-cell phenotype. In less than half of all cases, Epstein-Barr virus (EBV) infected the giant cells. A mixed EBV-A and -B type was found in 3, and a multiple genotype of EBV lymphocyte-determined membrane antigen (LYDMA) was found in 6 cases. These results could have been due to the immunodeficient status of the patients. A single-cell PCR of the giant cell, B cell, CD4+ or CD8+ T cells could be performed after cell sorting in 4 cases. HTLV-I infection was frequently found in the CD4+ T cells, but in neither the giant cells nor the B cells. The CD4+ T cells exhibited clonality. The giant cells showed various PCR products of IgH, and also expressed recombination activating genes (RAG). In summary, the giant cells were reactive cells, which resembled the immature B-lineage cells, while HTLV-I infected the CD4+ T cells, which demonstrated clonality. Based on these above findings, we consider CD4+ cells to play an important role in ATLL tumorigenesis.

Screening for Human T-cell Lymphotrophic Virus type-I (HTLV-I) infection in high risk schizophrenic patients

The Mashhadi-Jewish community originating in Iran is a closed and ethnically segregated population with a unique history and a high rate of intra-familial marriage among its members. High infection rate (23%) by Human T-Lymphotrophic Virus type-I (HTLV-I) was found in this population. The known modes of HTLV-I transmission are by sexual intercourse, from mother to child in breast milk, via blood transfusion, and by sharing of needles by parenteral drug users. In the present study we examined the presence of HTLV-I infection in high-risk psychiatric patients of Iranian origin in order to evaluate the infection rate in socially isolated subjects. We screened and examined all (N=42) Iranian-born schizophrenic patients in our center, of whom 17 were Mashhadi subjects (7 females, 10 males, mean age 48.7±13.2 years), and 25 were born in Iran in other cities than Mashhad (12 females, 13 males, mean age 43.2±11.9). Blood samples were tested for HTLV-I antibodies by particle agglutination test. The polymerase chain reaction (PCR) was used to detect HTLV-I proviral DNA sequences from peripheral blood mononuclear cells. One Mashhadi-born Jew (5.9%) was seropositive and PCR-positive for HTLV-I. None of the schizophrenic non-Mashhadi Iranian subjects was positive for HTLV-I by either method. This infection rate in schizophrenic patients of Mashhadi origin is significantly lower than rates reported for the normal Mashhadi community. We suggest that the relative isolation imposed by the stigma associated with mental illness and recurrent psychiatric hospitalizations serve to protect this sub-group from HTLV-I infection.

Association of HTLV-I with autoimmune thyroiditis in patients with adult T-cell leukaemia (ATL) and in HTLV-I carriers.

Human T-lymphotrophic virus type I (HTLV-I) is a retrovirus that causes adult T-cell leukaemia (ATL). This virus is associated with a variety of autoimmune disorders. The possible association between HTLV-I Infection and autoimmune thyroiditis has not been fully studied. We therefore evaluated anti-thyroid peroxidase antibodies (TPOAb) and anti-thyroglobulin antibodies (TGAb) in the sera of patients with ATL, carriers of HTLV-I, and in healthy control subjects to investigate the possible association between such infection and auto-immune thyroiditis. Fifty-two ATL patients (21 males, 31 females; mean age 56.4 years) and 50 HTLV-I carriers (18 males, 32 females; mean age 56.7 years) were studied. The control subjects were 877 healthy adults (271 males, 606 females; mean age 54.8 years) who were negative for HTLV-I antibody. TPOAb, TGAb, thyroxine (T4) and thyrotrophin (TSH) were measured in serum using a radioimmunoassay kit. Positivity for thyroid autoantibodies (TPOAb and/or TGAb) was found in 21 of 52 ATL patients (40.4%), 15 of 50 HTLV-I carriers (30.0%), and 120 of 877 control subjects (13.7%). The difference between the HTLV-I-Infected and the control subjects was statistically significant (P < 0.005). Female control subjects had a significantly higher prevalence of positivity for thyroid autoantibodies than the males (17.3 vs 5.5%, P < 0.001). Carriers of HTLV-I and patients with ATL of each sex showed an equally high prevalence of positivity for thyroid autoantibodies. Of the subjects who were positive for thyroid autoantibody, 7.5% of control subjects, 19.0% of ATL patients, and 40.0% of HTLV-I carriers had hypothyroidism. A significant difference in this respect was noted between the HTLV-I infected subjects and the control subjects (P < 0.005). This study demonstrates a high prevalence of positivity for thyroid autoantibodies (TPOAb and/ or TGAb) in the adult T-cell leukaemia patients and the HTLV-I carriers. The adult T-cell leukaemia patients and the HTLV-I carriers each had a high prevalence of hypothyroidism. There was an association between HTLV-I infection and autoimmune thyroiditis.

The potential roles of endogenous retroviruses in autoimmunity.

Endogenous retroviruses (ERVs) are estimated to comprise up to 1% of human DNA. While the genome of many ERVs is interrupted by termination codons, deletions or frame shift mutations, some ERVs are transcriptionally active and recent studies reveal protein expression or particle formation by human ERVs. ERVs have been implicated as aetiological agents of autoimmune disease, because of their structural and sequence similarities to exogenous retroviruses associated with immune dysregulation and their tissue-specific or differentiation-dependent expression. In fact, retrovirus-like particles distinct from those of known exogenous retroviruses and immune responses to ERV proteins have been observed in autoimmune disease. Quantitatively or structurally aberrant expression of normally cryptic ERVs, induced by environmental or endogenous factors, could initiate autoimmunity through direct or indirect mechanisms. ERVs may lead to immune dysregulation as insertional mutagens or cis-regulatory elements of cellular genes involved in immune function. ERVs may also encode elements like tax in human T-lymphotrophic virus type I (HTLV-I) or tat in human immunodeficiency virus-I (HIV-I) that are capable of transactivating cellular genes. More directly, human ERV gene products themselves may be immunologically active, by analogy with the superantigen activity in the long terminal repeat (LTR) of mouse mammary tumour viruses (MMTV) and the non-specific immunosuppressive activity in mammalian type C retrovirus env protein. Alternatively, increased expression of an ERV protein, or expression of a novel ERV protein not expressed in the thymus during acquisition of immune tolerance, may lead to its perception as a neoantigen. Paraneoplastic syndromes raise the possibility that novel ERV-encoded epitopes expressed by a tumour elicit immunity to cross-reactive epitopes in normal tissues. Recombination events between different but related ERVs, to whose products the host is immunologically tolerant, may also generate new antigenic determinants. Frequently reported humoral immunity to exogenous retrovirus proteins in autoimmune disease could be elicited by cross-reactive ERV proteins. A review of the evidence implicating ERVs in immune dysfunction leads to the conclusion that direct molecular studies are likely to establish a pathogenic role for ERVs in autoimmune disease.

Detection of human T lymphotrophic virus type I (HTLV-I) DNA and mRNA in individual cells by polymerase chain reaction (PCR) in situ hybridization (ISH) and reverse transcription (RT)-PCR ISH.

Human T lymphotrophic virus type I (HTLV-I) proviral DNA and mRNA in the blood obtained directly from HTLV-I infected adult T cell leukemia (ATL) patients were amplified by the polymerase chain reaction (PCR), and reverse transcription (RT)-PCR, and then were hybridized to fluorescein-labelled probes by means of in situ hybridization (ISH). Before the cytospin samples were prepared, heterogenous cell populations were reproducibly resolved into HTLV-I-positive and -negative distributions. Immunohistochemical staining was performed, using anti-fluorescein monoclonal antibody. Microscopic observations demonstrated a preserved cellular morphology. The intranuclear localization of amplified DNA products of proviral HTLV-I by PCR/ISH, and intracytoplasmic localization of amplified DNA of HTLV-I tax/rex mRNA by RT-PCR/ISH were maintained. In this study, about one in 10 HTLV-I provirus integrated cells expressed low copies of tax/rex mRNA. In HTLV-I-negative cell lines, amplified DNA was not observed by either PCR/ISH or RT-PCR/ISH. With the use of this technique it is thus possible to detect single-copy DNA and a few copies of mRNA, and it is therefore possible to study, not only suspended materials, but also other tissue materials for further characterization, in association with the localization of the HTLV-I infected cells.

Detection of human T-lymphotrophic virus type-I DNA and mRNA in the lymph nodes; using polymerase chain reactionin situ hybridization (PCR/ISH) and reverse transcription (RT-PCR/ISH)

To examine the relationship between human T-lymphotrophic virus type I (HTLV-I) proviral DNA and its expression in the lymph nodes, HTLV-I DNA and tax/rex mRDA were directly amplified by polymerase chain reaction in situ hybridization (PCR/ISH), and reverse transcription (RT)-PCR/ISH [RT-PCR/ISH]. We studied 24 lymph nodes from patients with adult T-cell leukemia/lymphoma (ATLL), incipient ATLL (I-ATLL), and HTLV-I associated lymphadenitis dermatopathic type (HAL-D) and enlarged paracortical type (HAL-EP). In ATLL, 40-60% of the nucleated cells were positive for for HTLV-I proviral DNA by PCR/ISH, while in I-ATLL and HAL, respectively 5-20% and less than 1-5% of cells were positive. The number of mRNA expressing cells was smaller than that of the proviral DNA-positive cells. The mRNA-expressing cells varied in number among the ATLL and I-ATLL cases, while they were only rarely observed in HAL-D and HAL-EP. These results show that HTLV-I infection and activation might increase with malignant transformation of the target T helper cells.

Detection of human T lymphotrophic virus type I (HTLV-I) proviral DNA and analysis of T cell receptor V beta CDR3 sequences in spinal cord lesions of HTLV-I-associated myelopathy/tropical spastic paraparesis.

Identification of the localization of human T lymphotrophic virus type I (HTLV-I) proviral DNA in the central nervous system (CNS) is crucial to the understanding of the pathogenesis of HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP) pathogenesis. We have developed a sensitive detection method, called two-step polymerase chain reaction (PCR) in situ hybridization, which enabled us to detect the HTLV-I proviral DNA in paraffin-embedded spinal cord tissue sections from HAM/TSP patients. HTLV-I proviral DNA was detected only in the nucleus of lymphocytes that had infiltrated into the spinal cord. However, no proviral DNA was amplified in any neuronal cells, including neurons and glial cells. This indicates that the demyelination of the spinal cord by HTLV-I as a result of viral infection of oligodendrocytes or neuronal cells is unlikely. The T cell receptor V beta gene sequence from lymphocytes in the spinal cord lesions taken from the same HAM/TSP autopsy cases revealed unique and restricted CDR3 motifs, CASSLXG(G) (one-letter amino acid. X is any amino acid), CASSPT(G), and CASSGRL which are similar to those described in T cells from brain lesions of multiple sclerosis (MS) and in a rat T cell clone derived from experimental allergic encephalomyelitis (EAE) lesions. The present results suggest that T cells containing restricted V beta CDR3 motifs, which are also found in MS and EAE, become activated upon HTLV-I infection and infiltrate into the spinal cord lesions of HAM/TSP patients.

Primate T-Lymphotropic Virus Type I LTR Sequence Variation and Its Phylogenetic Analysis: Compatibility with an African Origin of PTLV-I

Due to the low evolutionary rate and the limited horizontal transmission of human T-lymphotrophic virus type I (HTLV-I), its phylogenetic analysis reveals the movements and contacts of ancient populations. Since simian strains cannot be distinguished from human strains by phylogenetic criteria, this virus has appropriately been called primate T-lymphotropic virus type I (PTLV-I). We sequenced the LTR of six PTLV-I strains: three HTLV-I strains from African patients with tropical spastic paraparesis (TSP) (Equateur, Zaire), two laboratory HTLV-I strains of Japanese origin, MT-2 and MT-4, and one STLV-I from a baboon of the primate center in Sukhumi, Georgia. We applied four phylogenetic inference methods: neighbor-joining (NJ), unweighted pair group method using arithmetic averages (UPGMA), Fitch and Wagner parsimony (pars), and maximum likelihood (ML), to these 6 LTR sequences and 18 published LTR sequences (cosmopolitan, African, and Melanesian HTLV-I strains and African and Asian STLV-I strains). Three major HTLV-I subtypes can be identified with all four methods: the cosmopolitan HTLV-Ia, the central African HTLV-Ib, clearly descendant from a STLV-I CH-like African ancestral simian strain, and the Melanesian HTLV-Ic, probably descendant from an Asian STLV-I strain. We observe a segregation of PTLV-I sequences according to their geographical origin and not according to host species. The Zairean strains form a cluster closely related to an STLV-I strain isolated from a chimpanzee (STLV-I CH) and distinct from western African strains, which belong to the cosmopolitan subtype of HTLV-I. The Sukhumi STLV-I strain found in a captive-born baboon was of Asian descent. We experienced rooting problems with UPGMA when using HTLV-II as an outgroup. Concordant results with all four methods were obtained by eliminating HTLV-II LTR sequence fragments with bad alignment to HTLV-I. This resulted in a HTLV-II root node on the African STLV-I TAN9O terminal branch (with bootstrap values above 92% for the NJ and pars methods) and not on the Asian STLV-I PtM3 branch, as has been derived by others based on their use of UPGMA. The results of the analyses also support a higher evolutionary rate of PTLV-I in Asia, implying that the trees obtained with the NJ and ML methods have a higher reliability. These results are more compatible with an ancient African origin of PTLV-I than with an Asian origin.

Two color flow cytometric analysis of lymphocytes in HTLV-I carrier children.

Phenotypic changes in lymphocytes from healthy children with antibody for human T lymphotrophic virus type I (HTLV-I) were studied using two color flow cytometry. The subjects were high school students within a small district of Kyushu, Japan. In the carrier group, a subset of lymphocytes which expressed CD8+CD57+ was significantly lower in percentage (P < 0.01) and in number (P < 0.05). There was no significant difference between carriers and non-carriers in the percentage and number of CD4+Leu8+ cells or CD4+HLA-DR+ cells. The IgG levels were slightly higher in carriers than in non-carriers (P < 0.05). These findings suggest that HTLV-I-infected cells may affect the immune system in healthy carrier children.

Characterization of HTLV-I in vivo infected T cell clones. IL-2-independent growth of nontransformed T cells.

Mononuclear cells from subjects infected with human T lymphotrophic virus type I (HTLV-I) display a unique ability to proliferate in vitro in the absence of mitogens or exogenous growth factors. Subjects who have developed an HTLV-I-associated myelopathy (HAM) show an even higher degree of spontaneous proliferation concomitant with transcription of the HTLV-I provirus. The mechanism underlying HTLV-I-induced T cell activation was investigated by characterizing a series of HTLV-I-infected T cell clones generated from the blood of subjects with HAM. Approximately 15% of the T cell clones generated were HTLV-I infected as determined by polymerase chain reaction and Southern blotting. Infected T cell clones displayed altered growth kinetics as they continued to incorporate tritiated thymidine 7 to 14 days after stimulation, a time when noninfected T cell clones had returned to a resting state. This was not due to transformation as all the T cell clones required periodic restimulation with mitogens and feeder cells for continued growth. Although HTLV-I-infected T cell clones showed increased expression of the IL-2 receptor p55 chain, the spontaneous clonal proliferation was not inhibited by anti-IL-2 receptor mAb. Moreover, the spontaneous clonal proliferation was insensitive to cyclosporin A and FK 506 while being highly sensitive to rapamycin, which is known to inhibit IL-2-mediated signaling. Together these results demonstrate that IL-2 is not required for the HTLV-I-induced spontaneous clonal proliferation and further suggest that HTLV-I may induce signaling pathways replacing an IL-2 receptor signal proximal to the site of action of rapamycin.

Ribosome‐lamella complexes observed in an epstein‐barr virus‐producing B‐cell line, infected with human T‐lymphotropic virus type I

Co-cultivation of peripheral blood mononuclear cells, from a 4-year-old boy with infectious mononucleosis, with a human T lymphotrophic virus type I (HTLV-I)-producing T-cell line resulted in the establishment of an HTLV-I infected Epstein-Barr virus (EBV)-producing B-cell line. Ultrastructural examination revealed the presence of ribosome-lamella complexes (RLCs), in a small proportion of long-term cultured cells. Evidence is presented of continuity between RLC and the rough endoplasmic reticulum, and in some instances there was also an intimate relationship with tubuloreticular structures. The findings support the view that RLC is derived from the rough endoplasmic reticulum and also provide further evidence of the non-specific nature of RLC in relation to cell type.