Koichiro Usuku

Analysis Of Htlv-I Proviral Load In 202 Ham/Tsp Patients And 243 Asymptomatic Htlv-I Carriers: High Proviral Load Strongly Predisposes To Ham/Tsp

In order to examine the effect of HTLV-I proviral load on the pathogenesis of HAM/TSP, we measured the HTLV-I proviral load in peripheral blood mononuclear cells (PBMC) from a large number of HAM/TSP patients and asymptomatic HTLV-I carriers. To measure the proviral load, we used an accurate and reproducible quantitative PCR method using a dual-labeled fluorogenic probe (ABI PRISM 7700 Sequence Detection System). The mean + standard error of mean (s.e.m.) HTLV-I proviral copy number per 1 × 104 PBMC was 798 ±51 (median 544) in 202 HAM/TSP patients; 120 ± 17 (median 34) in 200 non HAM-related (general) asymptomatic HTLV-I carriers (RC); and 496 ± 82 (median 321) in 43 asymptomatic HTLV-I carriers genetically related to HAM/TSP patients (FA). The prevalence of HAM/TSP rises exponentially with log (proviral load) once the proviral load exceeds 1% PBMC. The HTLV-I proviral load of female patients with HAM/TSP was significantly higher than that of male patients, however there was no significant difference in p...

The Influence of HLA Class I Alleles and Heterozygosity on the Outcome of Human T Cell Lymphotropic Virus Type I Infection

The inflammatory disease human T cell lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM/TSP) occurs in only 1–2% of HTLV-I-infected individuals and is associated with a high provirus load of HTLV-I. We hypothesize that a person’s risk of developing HAM/TSP depends upon the efficiency of their immune response to the virus, which differs between individuals because of polymorphism in genes that influence this response. Previously we showed that the possession of HLA-A*02 was associated with a lower risk of HAM/TSP, and with a lower provirus load in healthy carriers of HTLV-I. However, HLA-A*02 did not account for all the observed difference in the risk of HAM/TSP. Here we present evidence, in the same study population in Japan, that HLA-Cw*08 was also associated with disease protection (probability value, two-tailed test = 0.002) and with a lower proviral load in healthy carriers. Possession of the A*02 and/or Cw*08 genes prevented 36% of potential HAM/TSP cases. In contrast, HLA-B*5401 was associated with a higher susceptibility to HAM/TSP (probability value, two-tailed test = 0.0003) and with a higher provirus load in HAM/TSP patients. At a given provirus load, B*5401 appeared to increase the risk of disease. The fraction of HAM/TSP cases attributable to B*5401 was 17%. Furthermore, individuals who were heterozygous at all three HLA class I loci have a lower HTLV-I provirus load than those who were homozygous at one or more loci. These results are consistent with the proposal that a strong class I-restricted CTL response to HTLV-I reduces the proviral load and hence the risk of disease.

HTLV-I proviral load correlates with progression of motor disability in HAM/ TSP: Analysis of 239 HAM/ TSP patients including 64 patients followed up for 10 years

To clarify clinical and laboratory findings that may be related to the pathomechanism of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), we analyzed these findings in 239 patients with HAM/TSP, including 64 patients followed up for 10 years after their first examinations, with special interest in the HTLV-I proviral load in peripheral blood mononuclear cells (PBMCs). The proviral load in PBMCs did not differ in terms of modes of HTLV-I transmission. However, the proviral load in patients with age of disease onset greater than 65 years tended to be higher than those with a younger age of onset. In the 64 patients followed up for 10 years, the clinical symptoms deteriorated in 36 patients (56%), unchanged in 26 patients (41%), and improved in 2 patients (3%). HTLV-I proviral load also appeared to be related to the deterioration of motor disability in these patients. To our knowledge, the present study is the first longitudinal study concerning the relationship between the clinical course of HAM/TSP and HTLV-I proviral load. It is suggested that HTLV-I proviral load is related to the progression of motor disability and is an important factor to predict prognosis of patients with HAM/TSP.

Phylogenetic Subgroups of Human T Cell Lymphotropic Virus (HTLV) Type I in the tax Gene and Their Association with Different Risks for HTLV-I—Associated Myelopathy/Tropical Spastic Paraparesis

The association between human T cell lymphotropic virus (HTLV) type I tax variation and disease outcome was studied. The tax gene was sequenced in 61 patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), 55 patients with adult T cell leukemia, and 62 healthy carriers (HCs). Phylogenetic analysis revealed 2 tax gene subgroups that are related on the basis of the long terminal repeat sequence. Further analysis using restriction fragment length polymorphism in 192 patients with HAM/TSP and 200 HCs revealed a higher incidence of 1 tax subgroup (taxA) in HAM/TSP. taxA was present in 30 (15.5%) of 192 patients with HAM/TSP and in 14 (7%) of 200 HCs. The difference was significant (chi2=6.47; P=.014; odds ratio, 2.46; 95% confidence interval, 1.26-4.80). This effect was independent of HLA-A*02, which has been reported to prevent HAM/TSP development. These findings suggest that both host genetic factors and HTLV-I subgroup are associated with different risks for development of HAM/TSP.

Zidovudine plus lamivudine in Human T-Lymphotropic Virus type-I-associated myelopathy: a randomised trial.

BackgroundNo therapies have been proven to persistently improve the outcome of HTLV-I-associated myelopathy. Clinical benefit has been reported with zidovudine and with lamivudine in observational studies. We therefore conducted a randomised, double blind, placebo controlled study of six months combination therapy with these nucleoside analogues in sixteen patients.ResultsPrimary outcomes were change in HTLV-I proviral load in PBMCs and clinical measures. Secondary endpoints were changes in T-cell subsets and markers of activation and proliferation.Six patients discontinued zidovudine. No significant changes in pain, bladder function, disability score, gait, proviral load or markers of T-cell activation or proliferation were seen between the two arms. Active therapy was associated with an unexplained decrease in CD8 and non-T lymphocyte counts.ConclusionFailure to detect clinical improvement may have been due irreversible nerve damage in these patients with a long clinical history and future studies should target patients presenting earlier. The lack of virological effect but may reflect a lack of activity of these nucleoside analogues against HTLV-I RT in vivo, inadequate intracellular concentrations of the active moiety or the contribution of new cell infection to maintaining proviral load at this stage of infection may be relatively small masking the effects of RT inhibition.

Usefulness of proviral load measurement for monitoring of disease activity in individual patients with human T-lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis

High human T-lymphotropic virus type I (HTLV-I) proviral load in peripheral blood mononuclear cells (PBMCs) has been reported in patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and the proviral load has been reported to fluctuate in individual patients during the course of the disease. Clinical symptoms usually became stable after a prolonged period of symptom progression. However, the authors have experienced having some patients whose clinical manifestations suddenly became worse during the course of the disease. To clarify the role of high proviral load and its fluctuation in the pathogenesis of HAM/TSP, the authors measured the proviral load of serially taken PBMCs as well as of cerebrospinal fluid (CSF) cells from patients with HAM/TSP on long-term follow-up and compared these with their clinical manifestations. There was a wide distribution of proviral load, from 0.3 to 37.8 copies/100 PBMCs; however, the proviral load in individual patients was relatively stable during the course of the disease. Eighty-three percent of the patients with clinical worsening showed an increase in proviral load at the time point when clinical worsening was recorded, or at the preceding time point. The proviral loads in CSF cells were higher than those in PBMCs in individual patients. The ratio of proviral loads in CSF cells/in PBMCs, but not the absolute load, in either compartment, was significantly associated with clinically progressive disease and with recent onset of HAM/TSP. These findings indicate that clinical progression of HAM/TSP is associated with increased proliferation or immigration of HTLV-I-infected lymphocytes in the central nervous system.

Detection of human T-lymphotropic virus type I p40tax protein in cerebrospinal fluid cells from patients with human T-lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis

We investigated the role of viral transcripts of human T-lymphotropic virus type I (HTLV-I) in the cerebrospinal fluid (CSF) cells and peripheral blood mononuclear cells (PBMCs) of patients with human T-lymphotropic virus type I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). To detect the HTLV-I p40tax protein, we developed a new sensitive method of immunohistochemistry combined with tyramide signal amplification and quantitative analysis. Seven patients with HAM/TSP were examined. As controls, four patients with other neurological diseases were examined; two of these patients were infected with HTLV-I and the other two were not. Both the CSF cells and PBMCs were reacted with a monoclonal antibody, Lt-4, for p40tax protein, followed by secondary antibody labeled with horseradish peroxidase. This was visualized by fluorescein directly labeled with tyramide and the number of positive cells was quantified with a Laser Scanning Cytometer. In the samples from patients with HAM/TSP, the HTLV-I p40tax protein was successfully detected by tyramide signal amplification, but not without it. In HAM/TSP patients, 0.04-1.16% of the CSF cells and 0.02-0.54% of PBMCs were positive for the HTLV-I p40tax protein, respectively. The expression of the HTLV-I p40tax protein in the CSF cells was more frequent than that in PBMCs in both HAM/TSP patients and HTLV-I carriers, and was also more frequent in the patients with HAM/TSP of shorter duration of illness. This technique could be a powerful tool to investigate the pathogenic mechanism of diseases associated with HTLV-I.

Cytotoxic T–cell abundance and virus load in human immunodeficiency virus type 1 and human T–cell leukaemia virus type 1

The correlation between virus load and specific cytotoxic T–lymphocyte (CTL) frequency during the chronic phase in human immunodeficiency virus type 1 (HIV–1) infection has been found to be negative in cross–sectional studies. We report here that, in infection with the related retrovirus human T–cell leukaemia virus type 1 (HTLV–1), the correlation is positive in asymptomatic carriers and zero in patients with the associated inflammatory disease HTLV–1–associated myelopathy/tropical spastic paraparesis (HAM/TSP). We demonstrate that the direction of the correlation may depend on the efficacy of the CTL response using mathematical models. We conclude that the CTL response is effective in asymptomatic carriers of HTLV–1, but ineffective in patients with HAM/TSP. Virus–mediated impairment of specific CTL production in HIV–1 infection can account for the negative correlation observed.

KIR2DL2 Enhances Protective and Detrimental HLA Class I-Mediated Immunity in Chronic Viral Infection

Killer cell immunoglobulin-like receptors (KIRs) influence both innate and adaptive immunity. But while the role of KIRs in NK-mediated innate immunity is well-documented, the impact of KIRs on the T cell response in human disease is not known. Here we test the hypothesis that an individuals KIR genotype affects the efficiency of their HLA class I-mediated antiviral immune response and the outcome of viral infection. We show that, in two unrelated viral infections, hepatitis C virus and human T lymphotropic virus type 1, possession of the KIR2DL2 gene enhanced both protective and detrimental HLA class I-restricted anti-viral immunity. These results reveal a novel role for inhibitory KIRs. We conclude that inhibitory KIRs, in synergy with T cells, are a major determinant of the outcome of persistent viral infection.

A prospective uncontrolled trial of fermented milk drink containing viable Lactobacillus casei strain Shirota in the treatment of HTLV-1 associated myelopathy/tropical spastic paraparesis.

Ten patients with human T-cell lymphotropic virus type-1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) were treated in an uncontrolled preliminary trial by oral administration of viable Lactobacillus casei strain Shirota (LcS) containing fermented milk. HTLV-1 provirus load, motor function, neurological findings, and immunological parameters were evaluated after 4 weeks. Although LcS did not change the frequencies or absolute numbers of all the examined cell surface phenotypes of peripheral blood mononuclear cells, NK cell activity was significantly increased after 4 weeks of oral administration of LcS preparation. Improvements in spasticity (modified Ashworth Scale scores) and urinary symptoms were also seen after LcS treatment. No adverse effect was observed in all the 10 patients throughout the study period. Our results indicated that LcS may be a safe and beneficial agent for the treatment of HAM/TSP; therefore randomized controlled studies are warranted.