Lack of antibody to HTLV-I and HIV in patients with multiple sclerosis from France and French West Indies

Viruses and Bacteria Associated with Cancer: An Overview

There are several human viruses and bacteria currently known to be associated with cancer. A common theme indicates that these microorganisms have evolved mechanisms to hamper the pathways dedicated to maintaining the integrity of genetic information, preventing apoptosis of the damaged cells and causing unwanted cellular proliferation. This eventually reduces the ability of their hosts to repair the damage(s) and eventually results in cellular transformation, cancer progression and reduced response to therapy. Our data suggest that mycoplasmas, and perhaps certain other bacteria with closely related DnaKs, may also contribute to cellular transformation and hamper certain drugs that rely on functional p53 for their anti-cancer activity. Understanding the precise molecular mechanisms is important for cancer prevention and for the development of both new anti-cancer drugs and for improving the efficacy of existing therapies.

Tampering of Viruses and Bacteria with Host DNA Repair: Implications for Cellular Transformation

A reduced ability to properly repair DNA is linked to a variety of human diseases, which in almost all cases is associated with an increased probability of the development of cellular transformation and cancer. DNA damage, that ultimately can lead to mutations and genomic instability, is due to many factors, such as oxidative stress, metabolic disorders, viral and microbial pathogens, excess cellular proliferation and chemical factors. In this review, we examine the evidence connecting DNA damage and the mechanisms that viruses and bacteria have evolved to hamper the pathways dedicated to maintaining the integrity of genetic information, thus affecting the ability of their hosts to repair the damage(s). Uncovering new links between these important aspects of cancer biology might lead to the development of new targeted therapies in DNA-repair deficient cancers and improving the efficacy of existing therapies. Here we provide a comprehensive summary detailing the major mechanisms that viruses and bacteria associated with cancer employ to interfere with mechanisms of DNA repair. Comparing these mechanisms could ultimately help provide a common framework to better understand how certain microorganisms are involved in cellular transformation.

HTLV tax: a fascinating multifunctional co-regulator of viral and cellular pathways

Human T-cell lymphotropic virus type 1 (HTLV-1) has been identified as the causative agent of adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The virus infects between 15 and 20 million people worldwide of which approximately 2-5% develop ATL. The past 35 years of research have yielded significant insight into the pathogenesis of HTLV-1, including the molecular characterization of Tax, the viral transactivator, and oncoprotein. In spite of these efforts, the mechanisms of oncogenesis of this pleiotropic protein remain to be fully elucidated. In this review, we illustrate the multiple oncogenic roles of Tax by summarizing a recent body of literature that refines our understanding of cellular transformation. A focused range of topics are discussed in this review including Tax-mediated regulation of the viral promoter and other cellular pathways, particularly the connection of the NF-κB pathway to both post-translational modifications (PTMs) of Tax and subcellular localization. Specifically, recent research on polyubiquitination of Tax as it relates to the activation of the IkappaB kinase (IKK) complex is highlighted. Regulation of the cell cycle and DNA damage responses due to Tax are also discussed, including Tax interaction with minichromosome maintenance proteins and the role of Tax in chromatin remodeling. The recent identification of HTLV-3 has amplified the importance of the characterization of emerging viral pathogens. The challenge of the molecular determination of pathogenicity and malignant disease of this virus lies in the comparison of the viral transactivators of HTLV-1, -2, and -3 in terms of transformation and immortalization. Consequently, differences between the three proteins are currently being studied to determine what factors are required for the differences in tumorogenesis.

The multifaceted oncoprotein Tax: subcellular localization, posttranslational modifications, and NF-κB activation

The human T-cell lymphotropic virus type-I (HTLV-I) is the etiologic agent of adult T-cell leukemia/lymphoma (ATL) and of tropical spastic paraparesis/HTLV-I-associated myelopathy. Constitutive NF-κB activation by the viral oncoprotein Tax plays a crucial role in the induction and maintenance of cellular proliferation, transformation, and inhibition of apoptosis. In an attempt to provide a general view of the molecular mechanisms of constitutive Tax-induced NF-κB activation, we summarize in this review the recent body of literature that supports a major role for Tax posttranslational modifications, chiefly ubiquitination, and SUMOylation, in the NF-κB activity of Tax. These modifications indeed participate in the control of Tax subcellular localization and modulate its protein-protein interaction potential. Tax posttranslational modifications, which highlight the ability of HTLV-I to optimize its limited viral genome size, might represent an attractive target for the design of new therapies for ATL.

Immune responses to antigens of human endogenous retroviruses in patients with acute or stable multiple sclerosis

A possible role for human endogenous retroviruses (HERV) in the pathogenesis of MS was investigated by analyzing HERV peptides-stimulated proliferation and cytokine production in MS patients with acute (AMS) or stable (SMS) disease. HERV peptides specific-proliferation and type 1 cytokine production by peripheral blood mononuclear cells was observed in AMS but not in SMS individuals, in whom a type 2 cytokine profile dominates. HERV peptides-stimulated immune responses were modified by changes in disease expression; mediated by CD4+ T lymphocytes; and not related to HLA class II molecules. These data suggest the possibility of a pathogenic role for HERV and HERV-specific immune responses in MS.

Epidemiologic evidence for multiple sclerosis as an infection

The worldwide distribution of multiple sclerosis (MS) can be described within three zones of frequency: high, medium, and low. The disease has a predilection for white races and for women. Migration studies show that changing residence changes MS risk. Studies of persons moving from high- to low-risk areas indicate that in the high-risk areas, MS is acquired by about age 15. Moves from low- to high-risk areas suggest that susceptibility is limited to persons between about ages 11 and 45. MS on the Faroe Islands has occurred as four successive epidemics beginning in 1943. The disease appears to have been introduced by British troops who occupied the islands for 5 years from 1940, and it has remained geographically localized within the Faroes for half a century. What was introduced must have been an infection, called the primary MS affection (PMSA), that was spread to and from successive cohorts of Faroese. In this concept, PMSA is a single widespread systemic infectious disease (perhaps asymptomatic) that only seldom leads to clinical neurologic MS. PMSA is also characterized by a need for prolonged exposure, limited age of susceptibility, and prolonged incubation. I believe that clinical MS is the rare late outcome of a specific, but unknown, infectious disease of adolescence and young adulthood and that this infection could well be caused by a thus-far-unidentified (retro)virus.

Do endogenous retroviruses have etiological implications in inflammatory and degenerative nervous system diseases?

Vertebrates carry large numbers of endogenous retroviruses (ERVs) and related sequences in their genomes. These retroviral elements are inherited as Mendelian traits. Generally, ERVs are defective without the ability of being expressed as viral particles. However, ERV sequences often have a potential for expression of at least some proteins. So far, the possible biological significance of ERVs is not clear. Nonetheless, there are observations suggesting a connection between ERVs and various diseases. This is the case with murine lupus and a spinal cord disease of certain mouse strains. In the present review, we discuss possible mechanisms by which ERVs could contribute to the development of human degenerative and inflammatory nervous system diseases, including direct effects on nervous system cells and immune cells. Interactions between ERVs and infectious viruses are also discussed. Finally, we review a possible retroviral etiology of multiple sclerosis.

In vitro transmission and antigenicity of a retrovirus isolated from a multiple sclerosis patient

We have recently isolated an apparently novel retrovirus (LM7) from a patient with multiple sclerosis (MS). We present here results showing that (1) LM7 retrovirus can be transmitted in vitro to a normal human leptomeningeal cell culture and that (2) specific antibody against this retroviral strain can be detected in MS cases. Our results suggest that, if this virus is an endogenous retrovirus, it is different from human endogenous elements already described.

Seroreactivity to human T cell leukemia/lymphoma virus type 1 and related retroviruses in multiple sclerosis patients from Denmark and the Faroes

A total of 40 multiple sclerosis (MS) patients from Denmark and 10 from the Faroes were examined for antibodies with affinity to human T cell leukemia/lymphoma virus type 1 (HTLV-I) and human immunodeficiency virus type 1 and 2 (HIV-1 and HIV-2). Using ELISA, MS patients and a group of healthy controls did not differ significantly in their reactivities to HTLV-I. However, elevated reactivities were recorded with 5 MS sera, whereas only 2 of the sera from the controls produced highly values. Ten patients with other neurological diseases all seemed to exhibit low reactivity in HTLV-I ELISA. The reactivities of 2 MS sera decreased considerably by absorption with an HTLV-I lysate. In immunofluorescence assay, two other MS sera reacted with HTLV-I transformed cell lines as well as with non-infected cells. Examined by Western blotting (WB), a single MS serum produced a distinct HTLV-I p19 band. With ELISA for detection of HIV-1 and HIV-2 antibodies, 2 MS sera exhibited borderline reactions. Further examination of these two sera by WB revealed weak reactivities against p24 and p53 of HIV-1. One the whole, the present observations do not suggest that a putative MS retrovirus would be closely related with HTLV-I, HIV-1 or HIV-2.

Antibody to reverse transcriptase of human retroviruses in multiple sclerosis

HTLV-1, HIV-1 and HIV-2 western blot analysis of sera from patients with multiple sclerosis (MS), from patients with other neurological diseases and from blood donors, revealed a rather frequent cross-reactivity with retroviral proteins in the MS group, though no patient was positive with the corresponding specific ELISA serology. Statistical analysis revealed a significant difference between the MS group and the two control groups for HIV-1 and HIV-2 reverse transcriptase fragments and for HTLV-1 p24. The general significance of these observations is discussed in the light of a retroviral hypothesis for the aetiology of MS. It is suggested that, if a retrovirus is present in MS patients, it does not necessarily belong to the HTLV sub-family and could as well be a lentivirus, like Visna virus, the causative agent of a demyelinating disease in sheep which is one--natural--model for MS.

No evidence of HTLV-I infection in French patients with multiple sclerosis using the polymerase chain reaction

The polymerase chain reaction (PCR), using three primer pairs in the pol, tax, and env regions of the HTLV-I genome, was unable to detect HTLV-I in the blood samples of 54 caucasian subjects with multiple sclerosis who were seronegative for HTLV-I/II. Seventeen HTLV-I/II seropositive (by ELISA and Western blot) subjects used as positive controls were positive with the three primer pairs. The PCR was negative in 47 healthy HTLV-I/II seronegative (by ELISA) subjects at low risk of HTLV-I infection used as negative controls. These results suggest that there is no association between the occurrence of HTLV-I sequences and the development of multiple sclerosis.

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

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

A review of the aetiology of multiple sclerosis: an ecological approach

Multiple sclerosis (MS) is a disease of unknown aetiology characterized by myelin destruction. Approaches to the aetiology of the condition have noted its differential geographic and demographic distribution; a tentative and inconsistent link with infectious agents; a genetic susceptibility; and a tendency to track with dietary lipids. This review proposes a multidisciplinary approach to the aetiology of MS, emphasizing the interlocking and interdependent nature of current aetiological arguments. We suggest that the most profitable interpretation of current empirical data on the aetiology of MS can be accomplished through this kind of analysis.

Immunological studies in tropical spastic paraparesis

Tropical spastic paraparesis (TSP) and other chronic-progressive myelopathies have been clearly associated with increased serum and cerebrospinal fluid antibody titers to human T-lymphotropic virus type I (HTLV-I). However, little is known about the cellular immune function in TSP. In the present study, activated T lymphocytes were found in the peripheral blood of patients with TSP. Specifically, there were increased numbers of large CD3+ cells that also expressed HLA-DR and interleukin-2-receptor molecules. A significantly elevated spontaneous lymphoproliferative response was demonstrated in all patients tested. Generation of measles virus-specific cytotoxic T-cell response was reduced in 4 of 4 patients. This was similar to previous findings in patients with multiple sclerosis. However, unlike multiple sclerosis, reduced generation of cytotoxic T-cell response to influenza and mumps viruses was observed in 2 of 4 patients. These observations confirm further the strong association between TSP and an HTLV-I-like virus and suggest that the observed abnormalities of the cellular immune response in TSP are related to infection of lymphocytes by the retrovirus.

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.

Retrovirus in multiple sclerosis

Presence of cytopathic effect and enzyme reverse transcriptase in cultures of peripheral blood mononuclear cells is described in 2 of 15 patients with multiple sclerosis and none of healthy controls. These findings might indicate: the presence of a new human retrovirus in these individuals, despite the low detection rate, and the shortcomings inherent in methodology used for detection of known human retroviruses in the study of new groups of diseases, such as those with possible autoimmune background.

Low-titer antibodies reactive with HTLV-I gag p19 in patients with chronic myeloneuropathy

To elucidate the possible association of human T-lymphotropic virus type I (HTLV-I) and chronic neurological diseases, 156 serum samples from patients with various neurological diseases, including multiple sclerosis, chronic progressive myelopathy, chronic inflammatory polyradiculoneuropathy, myasthenia gravis, polymyositis, motor neuron disease, and tension headache, and healthy control subjects were examined for IgG antibodies to HTLV-I by three independent techniques--gelatin particle agglutination test, enzyme-linked immunosorbent assay, and Western blot assay. Specificity of antibodies was assessed by homologous competitive inhibition on Western blot assay. Six patients (3 with chronic progressive myelopathy, 1 with chronic inflammatory polyradiculoneuropathy, 1 with motor neuron disease, and 1 with tension headache) had high-titer HTLV-I antibodies. Twelve patients (5 with multiple sclerosis, 1 with chronic progressive myelopathy, 2 with chronic inflammatory polyradiculoneuropathy, 2 with myasthenia gravis, and 2 with motor neuron disease) had low-titer HTLV-I antibodies that reacted with a single gag protein, p19 or p24, on Western blot assay. In 4 (2 with multiple sclerosis, 1 with chronic progressive myelopathy, and 1 with chronic inflammatory polyradiculoneuropathy) of these 12, the antibodies that were all directed to p19 were determined to be specific by homologous competitive inhibition. In the remaining 8 patients (3 with multiple sclerosis, 1 with chronic inflammatory polyradiculoneuropathy, 2 with myasthenia gravis, and 2 with motor neuron disease), restricted reactions against p19 or p24 were considered to be nonspecific because they were not inhibited by homologous competitive inhibition. The results suggest that in some patients chronic myeloneuropathy diagnosed as chronic progressive multiple sclerosis, chronic progressive myelopathy, and chronic inflammatory polyradiculoneuropathy may be associated with HTLV-I or related retroviruses.

Detection of sequences homologous to human retroviral DNA in multiple sclerosis by gene amplification

Twenty-one patients with multiple sclerosis, chronic progressive type, were examined for DNA sequences homologous to a human retrovirus. Genomic DNA from peripheral blood mononuclear cells was analyzed for the presence of homologous sequences to the human T-cell leukemia/lymphoma virus type I (HTLV-I) long terminal repeat, 3' gag, pol, and env domains by the enzymatic in vitro gene amplification technique, polymerase chain reaction. Positive identification of homologous pol sequences was made in the amplified DNA from six of these patients (29%). Three of these six patients (14%) also tested positive for the env region, but not for the other regions tested. In contrast, none of the samples from 35 normal individuals studied was positive when amplified and tested with the same primers and probes. Comparison of patterns obtained from controls and from patients with adult T-cell leukemia or tropical spastic paraparesis suggests that the DNA sequences identified are exogenous to the human genome and may correspond to a human retroviral species. The data support the detection of a human retroviral agent in some patients with multiple sclerosis.

Detection of human T-cell lymphoma/leukemia virus type I DNA and antigen in spinal fluid and blood of patients with chronic progressive myelopathy

The presence of antibodies to human T-cell lymphoma/leukemia virus Type I (HTLV-I) has been associated with chronic progressive myelopathy. We attempted to isolate the virus from the blood and spinal fluid of patients with chronic progressive myelopathy and to define the clinical, radiologic, and electrophysiologic features of this disease. Ten of 13 patients from tropical countries and 2 of 8 from the United States had serum antibodies to HTLV-I. The virus was detected in cultures of peripheral-blood lymphocytes from three of seven patients by means of Southern blot hybridization. Using a sensitive in vitro enzymatic gene-amplification technique, we detected HTLV-I sequences in fresh peripheral-blood mononuclear cells of all of 11 patients tested who were positive for the antibody, and in cell cultures of the spinal fluid from 3 of the 11 tested. Magnetic resonance imaging of the cranium revealed periventricular lesions in the white matter of 3 of the 12 antibody-positive patients. Five of these patients had mild axonal sensorimotor polyneuropathy, and one had bilateral lumbar radiculopathy. Visual evoked potentials were abnormal in three seropositive patients, and brain-stem evoked responses were abnormal in two. The detection of the DNA and proteins of HTLV-I strengthens the proposition that this virus is involved in the pathogenesis of a subset of cases of chronic progressive myelopathy.

Absence of antibodies to HTLV-I and HIV in serum and cerebrospinal fluid of Italian patients with multiple sclerosis

Because of the undecided question whether HTLV-related virus antibodies are present in multiple sclerosis (MS), we tested cerebrospinal fluid (CSF) and serum from 52 MS patients and 32 patients affected with other neurological diseases. ELISA procedure was used to detect antibodies against HTLV-I and HIV. Negative results were obtained in all samples examined.

Isolation of an HTLV-1-like retrovirus from patients with tropical spastic paraparesis

Tropical spastic paraparesis (TSP) is a slowly progressive myelopathy associated with increased serum and cerebrospinal fluid antibodies to the human T-lymphotropic retrovirus type I (HTLV-I) (ref. 1), and has been observed in many regions of the world. A similar condition known as HTLV-I-associated myelopathy occurs in the Kagoshima prefecture of Japan. Recent but controversial reports suggest involvement of virus related to HTLV-I in multiple sclerosis. Magnetic resonance imaging and electrophysiological studies indicate that TSP lesions are like multiple sclerosis in that they are disseminated throughout the nervous system. Complete virus from patients with TSP has proved difficult to isolate using techniques successful in adult T-cell leukaemia cases associated with HTLV-I. Here we report the isolation of an HTLV-I-like virus from T-cell lines derived from the peripheral blood and cerebrospinal fluid of TSP patients. The monoclonal antibody OKT3 was used to generate non-transformed T-cell lines that express HTLV-I antigens. Infectious virus was demonstrated by co-cultivation and complete, replicating virions were visualized ultrastructurally.

The role of HTLV-I in tropical spastic paraparesis in Jamaica

We report clinical and laboratory investigations of 47 native-born Jamaican patients with endemic tropical spastic paraparesis and of 1 patient with tropical ataxic neuropathy. Mean age at onset was 40 years, with a female-male preponderance (2.7:1). Neurological features of endemic tropical spastic paraparesis are predominantly those of a spastic paraparesis with variable degrees of proprioceptive and/or superficial sensory impairment. Using enzyme-linked immunoabsorbent assay (ELISA), IgG antibodies to human T-lymphotropic virus type I (HTLV-I) were present in 82% of sera and 77% of cerebrospinal fluids. On Western blot analysis, IgG antibodies detected the p19 and p24 gag-encoded core proteins in both serum and cerebrospinal fluid. Titers were tenfold higher by ELISA in serum than in cerebrospinal fluid, and some oligoclonal bands present in fluid were not seen in serum. Serum-cerebrospinal fluid albumin ratios were normal, and IgG indexes indicated intrathecal IgG synthesis. Histopathological changes showed a chronic inflammatory reaction with mononuclear cell infiltration, perivascular cuffing, and demyelination that was predominant in the lateral columns. In 1 patient, a retrovirus morphologically similar to HTLV-I on electron microscopy was isolated from spinal fluid. Our investigations show that endemic tropical spastic paraparesis in Jamaica is a retrovirus-associated myelopathy and that HTLV-I or an antigenically similar retrovirus is the causal agent.

Immunological findings in neurological diseases associated with antibodies to HTLV-I: activated lymphocytes in tropical spastic paraparesis

A retrovirus involvement in the etiology of certain neurological diseases is currently an area of intense interest. Tropical spastic paraparesis and other chronic progressive myelopathies have been clearly associated with increased serum and cerebrospinal fluid antibody titers to human T-lymphotropic virus type I; however, little is known about the cellular immune response. In the present study, activated T-lymphocytes were found in the peripheral blood of patients with this disorder. There were increased numbers of large CD3-positive cells that also expressed histocompatibility leukocyte Class II (DR) and interleukin 2-receptor molecules. In addition, a significantly elevated spontaneous lymphoproliferative response was demonstrated in all patients. This is consistent with the known in vitro effects of human T-lymphotropic virus type I. In one patient, a defect in the generation of measles virus-specific cytotoxic T cells was identified. These observations indicate abnormalities of the cellular immune response in tropical spastic paraparesis.

Multiple sclerosis and human T-cell lymphotropic retroviruses: negative serological results in 135 German patients

A total of 135 sera and 18 cerebrospinal fluid (CSF) samples from patients with multiple sclerosis (MS) were screened for antibodies to human T-cell lymphotropic virus type I (HTLV-I) and human immunodeficiency virus (HIV) by ELISA tests. None of the sera or CSF reacted with HIV antigens. Only 3 out of 135 MS sera but no MS CSF showed increased reactions in the ELISA test for HTLV-I. However, these positive reactions were classified as non-specific by immunoprecipitation. Thus no serological evidence for infection with HIV, HTLV-I, or a related retrovirus was found in the MS patients.

Endemic tropical spastic paraparesis associated with human T-lymphotropic virus type I: a clinical and seroepidemiological study of 25 cases

Tropical spastic paraparesis (TSP) is a common myeloneuropathy with primary and predominant involvement of the pyramidal tract and minimal sensory loss. The epidemic form of TSP is related to toxic nutritional factors, but the endemic form occurs in clusters in tropical areas, especially in India, Africa, the Seychelles, Colombia, and areas of the Caribbean. We describe the clinical and epidemiological features of 25 TSP patients from Martinique (French West Indies) with serum antibodies to human T-lymphotropic virus type I (HTLV-I). Furthermore, all 11 patients who were seropositive for HTLV-I had specific HTLV-I antibodies in their CSF. All were women. The age of onset varied from 25 to 60 years (mean, 45 years). The main clinical features are spastic paraparesis or paraplegia with spasticity of the upper limbs, minimal sensory loss, and bladder dysfunction. Minimal estimated incidence and prevalence are 1 per 100,000 inhabitants per year and 8 per 100,000, respectively. Seventeen percent of the relatives of patients with HTLV-I-associated TSP have HTLV-I antibodies (1 husband and 7 children). In Martinique, the prevalence of HTLV-I antibodies in the general population is about 2% and reaches 10% for neurological disorders other than TSP. Since our initial report, the association between spastic paraparesis and HTLV-I has been confirmed in Jamaica, Colombia, and Japan, suggesting the neurotropism of this lymphotropic human retrovirus.