HTLV-I Proviral Load Research Articles

In Vivo Fluctuation of HTLV-I and HTLV-II Proviral Load in Patients Receiving Antiretroviral Drugs

In Vivo Fluctuation of HTLV-I and HTLV-II Proviral Load in Patients Receiving Antiretroviral Drugs

HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP) with amyotrophic lateral sclerosis-like manifestations.

To clarify the existence of HAM/TSP presenting amyotrophic lateral sclerosis (ALS)-like manifestations, we assayed HTLV-I proviral load in peripheral blood mononuclear cells (PBMC) in 15 patients with anti-HTLV-I antibody in serum and ALS-like manifestations (upper motor neuron involvement in at least one region and lower motor neuron involvement in at least two limbs) by quantitative PCR, and compared the proviral load with that of 233 HAM/TSP patients and of 213 HTLV-I carriers. Five of 15 patients with ALS-like manifestations had proviral loads as high as those in the 233 patients with HAM/TSP. Anti-HTLV-I antibody in cerebrospinal fluid (CSF) was present in all of five patients. The proviral load in the remaining 10 patients was similar to that in HTLV-I carriers. Four of five patients with a high proviral load met the diagnostic criterion of HAM/TSP except for lower motor neuron involvement. These four patients showed high neopterin levels in CSF. On the basis of HTLV-I proviral load in PBMC and the clinical symptoms, our tentative conclusion is that these four patients are HAM/TSP presenting ALS-like manifestations.

Optic-spinal form of multiple sclerosis and immune-mediated myelopathy in Japan.

Optic-spinal form of multiple sclerosis (OS-MS) and HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP) are two immune-mediated myelopathy relatively common in Japan. (1) Transverse myelitis, once seen in 60% of MS, mostly OS-MS, 30 years ago, drastically decreased (5%) recently in Japan. In contrast, frequency of conventional form of MS (C-MS) increased during this period of time. But unlike C-MS in white patients, cerebellar hemispheric lesions are uncommon in Japanese C-MS. These findings emphasize influence of changes in exogenous factors on manifestations of MS and distinct genetic factors related to MS in Japanese and white patients. (2) To clarify the reason of high HTLV-I proviral load in HAM/TSP, we studied cellular immune surveillance against HTLV-I and found that significant cytotoxic T lymphocyte activity, and suppressed natural killer activity and antibody-dependent cell-mediated cytotoxicity in the patients. These altered immune surveillance may be associated with the spread of HTLV-I infection and the pathogenesis of HAM/TSP.

Molecular pathologic analysis of the tonsil in HTLV-I-infected individuals.

Little is known about the role of the tonsils in HTLV-I infection. We performed molecular pathologic studies of tonsils in individuals positive or negative for anti-HTLV-I antibodies (HTLV-I-Ab) to clarify histologic characteristics of tonsils in HTLV-I infection. We collected tonsils and peripheral blood samples from patients who underwent tonsillectomy in a prospective manner. HTLV-I-Ab in serum was examined and presence of HTLV-I provirus was detected by polymerase chain reaction (PCR) in extracted DNA of both peripheral blood and tonsils. Histopathologic and immunohistochemical evaluations of tonsils were performed. HTLV-I seropositivity and PCR detection of HTLV-I provirus matched perfectly. Tonsil samples from seropositive individuals showed atrophy of the mantle zone and high numbers of T cells in the marginal zone compared with findings in HTLV-I-negative samples. HTLV-I provirus could be detected only from extracted DNA of extrafollicular areas. PCR in situ hybridization also showed positive signals in some mononuclear cells located in the marginal zone. There was a significant correlation between HTLV-I proviral load in tonsils and in peripheral blood. These results suggest the presence of characteristic histologic changes and deviated localization of HTLV-I-infected cells in the tonsils of individuals positive for HTLV-I.

Prospective study of HTLV-I infection in an initially asymptomatic cohort.

A prospective clinical study of 20 initially asymptomatic HTLV-I-seropositive carriers was commenced in 1991 to determine the natural history of the infection in relation to HTLV-I proviral load, immune responses, and lymphocyte phenotype. Proviral load varied widely between carriers but was relatively constant within an individual over time. The lymphocyte phenotype and prevalence of activated lymphocytes were not predictive of disease and the magnitude of the cytotoxic T-lymphocyte response to HTLV-I was independent of proviral load. Incident conditions, some related to HTLV-I infection, including a case of HTLV-I-associated myelopathy (HAM), were documented in 9 carriers. Development of myelopathy and uveitis was associated with high peripheral blood HTLV-I proviral load that predated symptoms. Persistently high proviral load appears to predate the development of HTLV-I-associated inflammation in neuro-ophthalmic tissue.

Mother-to-child transmission of HTLV-I : implication of high antiviral antibody titer and high proviral load in carrier mothers.

P093 In order to gain new insight on the risk factors influencing HTLV-I mother-to-child transmission, a retrospective study of HTLV-I infection among children born to HTLV-I seropositive women was carried out in a highly HTLV-I endemic population of African origin living in French Guiana. Eighty-one HTLV-I seropositive mothers and their 216 children aged between 18 months old and 12 years old were included in the study. All plasma samples were tested for the presence of anti HTLV-I antibodies by ELISA, Immunofluorescence assay and Western Blot. HTLV-I provirus was detected, in the DNA extracted from PBMCs, by PCR using primers specific for 3 different HTLV-I genomic regions (LTR, gag and pX) and quantified by a competitive PCR assay. A perfect concordance between serological and PCR results was observed. None of the 195 HTLV-I negative children was found HTLV-I positive by PCR. Twenty-one children out of the 216 were found HTLV-I seropositive, giving a crude HTLV-I transmission rate of 9.7% while among the 180 breast fed children 10.6% were HTLV-I seropositive. In conditional (by family) logistic regression models, HTLV-I seropositivity in children was associated with an elevated maternal anti HTLV-I antibody titer (OR=2.2; p=0.0013), a high maternal HTLV-I proviral load (OR=2.6; p=0.033) and child's gender, girls being more frequently HTLV-I infected than boys (OR=3.6; p=0.0077 in the model including maternal anti HTLV-I antibody titer and OR=4.1; p=0.002 in the model including the maternal HTLV-I proviral load).

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 x 10(4) 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 proviral load between sexes in RC. There was a significant correlation between the proviral load and the concentration of neopterin in CSF of HAM/TSP patients. These results indicate that the HTLV-I proviral load in PBMC may be related to the inflammatory process in the spinal cord lesion. The increased proviral load in FA suggests the existence of genetic factors contributing to the replication of HTLV-I in vivo.

Long term, high dose interferon-alpha treatment in HTLV-I-associated myelopathy/tropical spastic paraparesis: a combined clinical, virological and immunological study

The efficacy of long-term, high dose interferon-α (IFN-α) therapy was studied in seven patients with HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). IFN-α was administered at a dose of 6 × 10 6 international units daily for the initial 2 weeks and thereafter 3 times a week for the following 22 weeks. Five patients showed a sustained improvement in motor performance during and up to 6 months after the completion of IFN-α. The other patient who responded to IFN-α initially dropped out at 3 months because of depression, while another patient first deteriorated and thereafter dropped out. In the six responders, the absolute number of peripheral blood lymphocytes (PBL) harboring the HTLV-I genome as evaluated by the quantitative polymerase chain reaction method decreased significantly during the therapy period (28.6 ± 16.6% reduction, P = 0.0083), whereas the one deteriorated patient showed a 2.5-fold increase in HTLV-I-infected cells. The autoproliferation of CD4 + T clone cells from a single cell culture was markedly depressed even after the cessation of IFN-α in the responders who completed long-term IFN-α therapy. In addition, the CD8 +DR + T cells in the peripheral blood and soluble IL-2 receptor levels in the sera increased significantly during the therapy in all patients ( P = 0.0431 and P = 0.0041, respectively). Therefore, the results of our study suggested that both the reduction of HTLV-I proviral DNA load and immunomodulation by long-term IFN-α therapy contributed to its sustained clinical benefits.

Pulmonary involvement in human T-cell lymphotropic virus type-I uveitis: T-lymphocytosis and high proviral DNA load in bronchoalveolar lavage fluid

The ocular manifestation of human T-cell lymphotropic virus type I (HTLV-I) infection has been recognized as a new clinical entity termed HTLV-I uveitis. In order to determine whether HTLV-I uveitis is associated with lymphocyte alveolitis, bronchoalveolar lavage (BAL) was carried out in 11 patients with HTLV-I uveitis, five asymptomatic HTLV-I carriers, 11 HTLV-I-negative patients with ocular sarcoidosis, and nine normal control subjects seronegative for HTLV-I. Six of the 11 patients with HTLV-I uveitis showed increased total cell counts, and T-lymphocytosis in BAL fluid. CD4+/CD8+ ratios of T-lymphocytes were decreased in three of these patients, and normal in three other patients. Such abnormalities of the lung were not found in asymptomatic HTLV-I carriers, and in normal control subjects. BAL findings in HTLV-I uveitis differed from those of patients with sarcoidosis in terms of the lymphocytic component. Interestingly, it was found that there was an increase of HTLV-I proviral deoxyribonucleic acid (DNA) load in peripheral blood mononuclear cells (PBMC) from seven patients with HTLV-I uveitis, and in the BAL cells from four patients with pulmonary involvement. These results provide further evidence in terms of HTLV-I tropism for the lung, and suggest that a systemic and local increase of HTLV-I proviral DNA load plays an important role in the pathogenesis of lymphocyte alveolitis in patients with HTLV-I uveitis.

Antibody titers to HTLV-I-p40 tax protein and gag-env hybrid protein in HTLV-I-associated myelopathy/tropical spastic paraparesis: Correlation with increased HTLV-I proviral DNA load

We studied the relationship between antibody titers to recombinant HTLV-I p40 tax protein and gag-env hybrid protein in serum (by an enzyme-linked immunosorbent assay) and HTLV-I proviral DNA load in peripheral blood mononuclear cells (by a quantitative polymerase chain reaction method) in 18 patients with HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP), 17 HTLV-I carriers without HAM/TSP and 16 HTLV-I uninfected controls. The IgG and IgA antibody titers to either of the proteins correlated significantly with the HTLV-I pX (coding p40 tax protein) and pol DNA amounts in HTLV-I infected subjects. HAM/TSP patients had significantly higher titers of IgG and IgA antibodies to the HTLV-I proteins than did the HTLV-I carriers without HAM/TSP. While the IgM antibodies to the HTLV-I proteins were found in only 6% of HTLV-I carriers without HAM/TSP, they were found in 40% of HAM/TSP patients, especially those having both a high HTLV-I proviral DNA load and high titers of the IgG and IgA antibodies. HAM/TSP patients with the IgM antibodies had a tendency to deteriorate more frequently on the Kurtzke's disability status scale and magnetic resonance imaging of the brain (leukoencephalopathy) than did those without in the two-year follow-up. Thus, the presence of IgM antibody and high titers of IgG and IgA antibodies to the HTLV-I proteins, together with the increased HTLV-I proviral DNA load, appears to distinguish HAM/TSP patients from HTLV-I carriers without HAM/TSP.