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

PCR-in situ hybridization detection of human T-cell lymphotropic virus type 1 (HTLV-1) tax proviral DNA in peripheral blood lymphocytes of patients with HTLV-1-associated neurologic disease

PCR-in situ hybridization (PCR-ISH) was developed and utilized to determine the distribution of human T-cell lymphotropic virus type 1 (HTLV-1) tax proviral DNA in peripheral blood lymphocytes (PBL) from patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). PCR-ISH of HTLV-1 tax DNA in PBL from patients with HAM/TSP revealed that 1 in 5,000 to 1 in 10,000 PBL contained virus. PCR-ISH was sensitive, because a positive signal was consistently demonstrated from the HTLV-1-infected cell lines HUT-102 (which contains four to six copies of HTLV-1 proviral DNA per cell) and MT-1 (which contains one to three copies of HTLV-1 proviral DNA per cell). Also, intracellular amplification by PCR-ISH significantly increased sensitivity compared with conventional ISH and was shown to be specific for HTLV-1 tax DNA. These results are in contrast to solution-phase PCR amplification in which greater than 1% of cells were estimated to be infected. The discordance between these results is discussed and may indicate that more than one copy of HTLV-1 tax proviral DNA is present in an individual PBL.

Analysis of the T-cell receptor repertoire of human T-cell leukemia virus type 1 (HTLV-1) Tax-specific CD8+ cytotoxic T lymphocytes from patients with HTLV-1-associated disease: evidence for oligoclonal expansion

Human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic, progressive neurological disease characterized by marked degeneration of the spinal cord and the presence of antibodies against HTLV-1. Patients with HAM/TSP, but not asymptomatic carriers, show very high precursor frequencies of HTLV-1-specific CD8+ T cells in peripheral blood and cerebrospinal fluid, suggestive of a role of these T cells in the pathogenesis of the disease. In HLA-A2+ HAM/TSP patients, HTLV-1-specific T cells were demonstrated to be directed predominantly against one HTLV-1 epitope, namely, Tax11-19. In the present study, we analyzed HLA-A2-restricted HTLV-1 Tax11-19-specific cytotoxic T cells from three patients with HAM/TSP. An analysis of the T-cell receptor (TCR) repertoire of these cells revealed an absence of restricted variable (V) region usage. Different combinations of TCR V alpha and V beta genes were utilized between, but also within, the individual patients for the recognition of Tax11-19. Sequence analysis of the TCR showed evidence for an oligoclonal expansion of few founder T cells in each patient. Apparent structural motifs were identified for the CDR3 regions of the TCR beta chains. One T-cell clone could be detected within the same patient over a period of 3 years. We suggest that these in vivo clonally expanded T cells might play a role in the pathogenesis of HAM/TSP and provide information on HTLV-1-specific TCR which may elucidate the nature of the T cells that infiltrate the central nervous system in HAM/TSP patients.

HAM/TSP: recent perspectives in Japan

Neurologic diseases associated with human T-cell lymphotropic virus type I (HTLV-I) infection have a clinical spectrum that includes myelopathy (HTLV-I-associated myelopathy/tropical spastic paraparesis, HAM/TSP) as the central manifestation. Many clinical signs of involvement outside the central nervous system (CNS) have been described in some patients with HAM/TSP and have triggered and advanced the discovery of some HTLV-I-associated concepts in HTLV-I-infected individuals without signs of CNS involvement. Most of these HTLV-I-associated diseases exhibit common viroimmunologic characteristics that include a distributional bias of HTLV-I activation between the blood flow and the affected lesions and accumulated cellular immune responses in the lesions. These facts suggest that the vulnerable tissue(s) in some HTLV-I-infected individuals may not be defined by an exclusive tissue specificity, but that common steps of HTLV-I-versus-host interactions may have an important role in the pathologic process(es) in these diseases. This review summarizes the recent perspectives of the clinical spectrum and the pathogenesis of HAM/TSP in Japan. Furthermore, the feasible pathogenic involvement of cellular interactions between infected cells and responding immunocompetent cells in the affected tissues is emphasized.

Cellular immune responses to HTLV-I: immunopathogenic role in HTLV-I-associated neurologic disease

This review examines current information on cellular immune responses to the human T lymphotropic virus type I (HTLV-I). HTLV-I has been associated with a number of diseases, but this review focuses primarily on the relationship of HTLV-I with a slowly progressive neurologic disorder termed HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). In particular, this review discusses the role of cellular immune responses to HTLV-I in patients with HAM/TSP and how these responses may be associated with the pathogenesis of this disorder. While a number of immunologic responses have been shown to be abnormal in HAM/TSP patients, studies on HTLV-I-specific cytotoxic T-cell responses (cytotoxic T lymphocytes) are specifically examined. By defining such antigen-specific functional cellular host responses to HTLV-I, we hope to understand better the underlying mechanisms that may be involved in the neuropathology of HTLV-I-associated neurologic disease. This has led to a number of HTLV-I-associated immuno-pathogenic models that may be operative in HAM/TSP patients. Importantly, based on these models, potential immunotherapeutic strategies for disease intervention can be devised. Moreover, such an analysis may have significant implications for our understanding of other HTLV-I-associated clinical disorders.

A search for human T-cell leukemia virus type I in the lesions of patients with tropical spastic paraparesis and polymyositis

We searched for the presence of human T-cell leukemia virus type I (HTLV-I) sequences in central nervous system and muscle lesions of 3 patients with tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM) and 3 patients with HTLV-I-associated polymyositis. Proviral DNA coding for the Tax protein was found by polymerase chain reaction amplification in DNA extracted from lesions of every patient with TSP/HAM or HTLV-I-associated polymyositis. In contrast, viral RNA was found occasionally by in situ hybridization in muscle lesions of some patients with polymyositis, but was never found in central nervous system lesions of TSP/HAM patients.

Is there a case for a virus aetiology in multiple sclerosis?

Multiple Sclerosis (MS) is a devastating demyelinating disease with a very high prevalence in North-East Scotland and in the Orkney and Shetland Islands. MS appears to be a multifactorial disorder with environmental and genetic elements and it has been proposed that these, in tandem, provoke an autoimmune response giving rise to the disease. Although there is no direct evidence of a specific virus being involved in MS, there are nevertheless grounds for suspecting a viral association. This review discusses these aspects of MS and suggests that a more aggressive approach to unravelling the role of viruses is needed.