Immunogenetics and the Pathological Mechanisms of Human T-Cell Leukemia VirusType 1- (HTLV-1-)Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP)

HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP): Case based discussion of risk factors, clinical, and therapeutic considerations

HTLV-1 is a retrovirus virus that infects CD4+ T cells. Most people with HTLV-1 infection remain asymptomatic but some may develop conditions such as HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) or adult T-cell leukemia/lymphoma. HAM/TSP is characterized by progressive spasticity and weakness of the lower extremities, as well as loss of bladder control and sensory disturbances. The risk of developing HAM/TSP is associated with the duration of infection and the proviral load. There is currently no cure for the disease but medications can help manage symptoms and slow the progression of the disease. This is the case of a 66-year-old female who presented with nonspecific symptoms of weakness and spasticity in a hospital in Connecticut and was subsequently diagnosed with HAM/TSP. The patient's diagnosis highlights the importance of considering diseases previously confined to specific endemic regions in a globalized world where increased emigration and population mixing can occur. Early identification and management of such cases is essential for optimizing patient outcomes and quality of life.

HTLV-1 Proviral Load Absolute RT-qPCR Development for Assessing on Clinical Outcomes in HAM/TSP Patients

Background

The significance of HTLV-1 proviral load as a prognostic biomarker in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) has been a subject of controversy. This study aims to assess the impact of HTLV-1 proviral load (PVL) on the clinical outcome in patients with HAM/TSP.

Methods

An absolute quantitative HTLV-1 PVL RT-qPCR, TaqMan method was developed with 100% sensitivity and specificity. Then, from 2005-2018, the HTLV-1 PVL of 90 eligible newly diagnosed HAM/TSP patients were assessed for demographic, clinical symptoms and their associations with HTLV-1-PVL.

Results

The quality control of the designed RT-qPCR showed a sensitivity and specificity of 100%. Spasticity in lower limbs in 58.9% and urinary symptoms in 17.8% of HAM/TSPs were observed. Using this designed RT-qPCR, the HTLV-1-PVL strongly affected spasticity and sphincter disturbance (p=0.05). The multivariate logistic test showed that only the beginning of lower limb weakness along with tremor was associated with PVL (OR: 2.78. 95% CI (0.99-1.02) and p=0.05). Urinary incontinence was prevalent among these patients; however, no association was identified with the HTLV-1 proviral load (PVL).

Conclusions

The absolute RT-qPCR developed for measuring HTLV-1 proviral load (PVL) demonstrated reliable results. Despite a high prevalence of urinary incontinence in these patients, no association was observed with the PVL. Consequently, it appears that HTLV-1 proviral load is specifically associated with developing spasticity in HAM/TSP.

Advances in the treatment of human T-cell lymphotropic virus type-I associated myelopathy

INTRODUCTION

Nearly 2-3% of those 10 to 20 million individuals infected with the Human T-cell lymphotropic virus type-1 (HTLV-1); are predisposed to developing HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). It is a neuro-inflammatory disease; differentiated from multiple sclerosis based on the presence of typical neurologic symptoms, confirmation of HTLV-1 infection, and other molecular biomarkers.

AREAS COVERED

A brief review of the epidemiology, host immune responses, and molecular pathogenesis of HAM/TSP is followed by detailed discussions about the host-related risk factors for developing HAM/TSP and success/failure stories of the attempted management strategies.

EXPERT OPINION

Currently, there is no effective treatment for HAM/TSP. Anti-retroviral therapy, peculiar cytokines (IFN-α), some anti-oxidants, and allograft bone marrow transplantation have been used for treating these patients with limited success. Under current conditions, asymptomatic carriers should be examined periodically by a neurologist for early signs of spinal cord injury. Then it is crucial to determine the progress rate to adapt the best management plan for each patient. Corticosteroid therapy is most beneficial in those with acute myelitis. However, slow-progressing patients are best managed using a combination of symptomatic and physical therapy. Additionally, preventive measures should be taken to decrease further spread of HTLV-1 infection.

Selective APC-targeting of a novel Fc-fusion multi-immunodominant recombinant protein (tTax-tEnv:mFcγ2a) for HTLV-1 vaccine development

AIMS

HTLV-1 causes two life-threatening diseases: adult T-cell leukaemia/lymphoma and HTLV-1-associated myelopathy/tropical spastic paraparesis. Due to the lack of proper treatment, an effective HTLV-1 vaccine is urgently needed.

MAIN METHODS

DNA sequences of 11-19 and 178-186 amino acids of HTLV-1-Tax and SP2 and P21 were fused to the mouse-Fcγ2a, or His-tag called ^tTax-^tEnv:mFcγ2a and ^tTax-^tEnv:His, respectively. These constructs were produced in Pichia pastoris, and their immunogenicity and protective properties were assessed in a mouse challenging model with an HTLV-1-MT2 cell line.

KEY FINDINGS

The immunogenicity assessments showed significant increase in IFN-γ production in animals receiving ^tTax-^tEnv:mFcγ2a (1537.2 ± 292.83 pg/mL) compared to ^tTax-^tEnv:His (120.28 ± 23.9, p = 0.02). IL-12 production also increased in group receiving ^tTax-^tEnv:mFcγ2a than ^tTax-^tEnv:His group, (23 ± 2.6 vs 1.5 ± 0.6, p = 0.01), respectively. The IFN-γ and IL-12 levels in the Fc-immunised group were negatively correlated with PVL (R = -0.82, p < 0.04) and (R = -0.87, p = 0.05), respectively. While, IL-4 was increased by ^tTax-^tEnv:His (21.16 ± 1.76 pg/mL) compared to ^tTax-^tEnv:mFcγ2a (13.7 ± 1.49, p = 0.019) with a negative significant correlation to PVL (R = -0.95, p = 0.001).

SIGNIFICANCE

The mouse challenging assay with ^tTax-^tEnv:mFcγ2a showed 50 % complete protection and a 50 % low level of HTLV-1-PVL compared to the positive control receiving HTLV-1-MT2 (p = 0.001). Challenging experiments for the His-tag protein showed the same outcome (p = 0.002) but by different mechanisms. The Fc-fusion construct induced more robust Th1, and His-tag protein shifted more to Th2 immune responses. Therefore, inducing both T helper responses, but a Th1/Th2 balance in favour of Th1 might be necessary for appropriate protection against HTLV-1 infection, spreading via cell-to-cell contact manner.

Occupational Therapy for People Living With Human T-Lymphotropic Virus 1: Importance and Effectiveness of an Intervention Plan at the Level of Prevention and Rehabilitation

Introduction

Human T-lymphotropic virus 1 (HTLV-1)-associated myelopathy (HAM) restricts activities of daily living (ADLs), affecting health and quality of life. Occupational therapy is used to promote independence during ADL in people living with HTLV (PLHTLV).

Objective

To quantify the clinical aspects, levels of functionality, performance in ADLs and occupational roles of PLHTLV and propose an occupational therapeutic intervention.

Method

A cross-sectional, descriptive, observational study was designed with 40 PLHTLV monitored at two referral laboratories of the Federal University of Pará. The Evandro Chagas Research Institute Neurological Disability Scale (EIPEC-2), the Barthel Index and the Occupational Roles Identification List were applied. The G test and Fisher’s exact test (to identify associations between qualitative variables), the Mann–Whitney test (to identify associations between quantitative variables) and Pearson correlation analysis (to identify associations between the total Barthel Index and EIPEC-2 scores) were performed with Microsoft Excel and BioEstat 5.0, and the significance level was set at p ≤ 0.05.

Results

Motor aspects, the presence of spasticity, sensory aspects, and pain in the lumbar region and lower limbs were significantly (p = 0.0002) higher among symptomatic individuals, who also had more difficulties urinating, traveling up and down stairs and transferring from a chair to a bed. Being a worker, performing housework and socializing (with friends or family members) were the most affected activities among HAM patients.

Conclusion

The impact of HAM on PLHTLV should include an intervention plan with occupational therapists in rehabilitation programs to create an important third-level prevention initiative, which may help achieve short-, medium-, and long-term goals. Asymptomatic PLHTLV should also be able to prevent future ADL impairment.

Evaluating mRNA expression of tax, B chain of PDGF and PDGF-β receptors as well as HTLV-I proviral load in ATL patients and healthy carriers

Adult T-cell leukemia (ATL) is a life-threatening malignant neoplasm of CD4+ T cells resulted from human T-cell leukemia virus type I (HTLV-I). Tax1 protein of HTLV-I can induce malignant proliferation of T-cells by modulating the expression of growth factors such as platelet-derived growth factor (PDGF). Here, we aimed to investigate the proviral load (PVL) of HTLV-I in ATL and also to evaluate the mRNA expression of B chain of PDGF and PDGF-β receptors in ATL patients and HTLV-I-infected healthy carriers. To this end, peripheral blood mononuclear cells (PBMCs) were isolated by using Ficoll-Histophaque density centrifugation. The mean of HTLV-I PVL in ATL patients (42,759 ± 15,737 copies/104 cells [95% CI, 9557-75962]) was significantly (p = .01) higher than that in healthy carriers (650 ± 107 copies/104 cells [95% CI, 422-879], respectively. The HTLV-I PVL in ATL patients exhibited a significant correlation with PBMC count (R = .495, p = .001). The mRNA expression of Tax, B chain of PDGF, and PDGF-β receptor genes was significantly higher in healthy carriers than in patients with ATL. In conclusion, the expression of the canonical PDGFβ and its receptor, and their correlation with Tax expression cannot be a suitable indicator and/or prognostic factor for progression of ATL in HTLV-I carriers.

Expression of TSLC1 in patients with HAM/TSP

Human T-lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is chronic myelopathy characterized by slowly progressive spastic paraparesis and urinary dysfunction. A few biomarkers in the cerebrospinal fluid are known to be related to disease activity, but no biomarker has been reported in peripheral blood. This study aims to explore the expression level of the adhesion molecule during the expression level of the adhesion molecule among HAM/TSP disease activity. In lymphocyte function-associated antigen 1 and DNAX accessory molecule 1, no variation in expression levels specific to HTLV-1 infection was observed in CD4-positive T cells; however, TSLC1 expression was higher in HAM patients than in asymptomatic carriers and non-infected persons. TSLC1 tended to be higher in patients whose symptoms were worsening. On the contrary, the expression level of TSLC1 in CD8-positive T cells was lower in HAM patients than in asymptomatic carriers, and this tendency was stronger in patients whose symptoms had deteriorated. No significant correlation was found between TSLC1 and either of the transcription factors Tax or HBZ in any T cell group. Therefore, TSLC1 expression in CD4-positive T cells might be a useful biomarker of HAM/TSP disease activity.

The IL-18, IL-12, and IFN-γ expression in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients, HTLV-1 carriers, and healthy subjects

Interleukin (IL)-12, IL-18, and interferon gamma (IFN-γ) can induce Th1-inflammatory responses in favor of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) manifestation. In this study, the gene expression and plasma levels of these cytokines were evaluated. The peripheral blood mononuclear cells (PBMCs) in 20 HAM/TSP patients, 21 asymptomatic carriers (ACs), and 21 healthy subjects (HSs) were assessed for the expression of IL-18, IL-12, and IFN-γ, using qRT-PCR. The plasma level of IL-18 and IFN-γ were measured by an ELISA method. The mean of HTLV-1 proviral load (PVL) in the HAM/TSPs was 1846.59 ± 273.25 and higher than ACs at 719.58 ± 150.72 (p = 0.001). The IL-12 was considerably expressed only in nine ACs, five HAM/TSPs, and all HSs. Furthermore, the gene expression and plasma levels of IL-18 were lower in the HTLV-1-positive group than the control group (p = 0.001 and 0.012, respectively); however, there was no significant difference between the ACs and HAM/TSPs. The IFN-γ level was higher in the HTLV-1-positive group (p < 0.001) than HSs. Although there were no correlation between plasma levels of IL-18 and IFN-γ with PVL in the ACs, a positive correlation was observed between plasma IL-18 levels and PVL (r = 0.654, p = 0.002). The highest levels of IFN-γ were observed in the HAM/TSPs which has a significant correlation with HTLV-1-HBZ (r = 0.387, p = 0.05) but not with Tax. However, no significant correlation was found between PVL and proinflammatory pattern. Apart from the IFN-γ as a lymphokine, as a host factor, and HTLV-1-HBZ, as a viral agent, the other proinflammatory monokines or HTLV-1 factors are among the less-effective agents in the maintenance of HAM/TSP.

An insight to HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) pathogenesis; evidence from high-throughput data integration and meta-analysis

BACKGROUND

Human T-lymphotropic virus 1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a progressive disease of the central nervous system that significantly affected spinal cord, nevertheless, the pathogenesis pathway and reliable biomarkers have not been well determined. This study aimed to employ high throughput meta-analysis to find major genes that are possibly involved in the pathogenesis of HAM/TSP.

RESULTS

High-throughput statistical analyses identified 832, 49, and 22 differentially expressed genes for normal vs. ACs, normal vs. HAM/TSP, and ACs vs. HAM/TSP groups, respectively. The protein-protein interactions between DEGs were identified in STRING and further network analyses highlighted 24 and 6 hub genes for normal vs. HAM/TSP and ACs vs. HAM/TSP groups, respectively. Moreover, four biologically meaningful modules including 251 genes were identified for normal vs. ACs. Biological network analyses indicated the involvement of hub genes in many vital pathways like JAK-STAT signaling pathway, interferon, Interleukins, and immune pathways in the normal vs. HAM/TSP group and Metabolism of RNA, Viral mRNA Translation, Human T cell leukemia virus 1 infection, and Cell cycle in the normal vs. ACs group. Moreover, three major genes including STAT1, TAP1, and PSMB8 were identified by network analysis. Real-time PCR revealed the meaningful down-regulation of STAT1 in HAM/TSP samples than AC and normal samples (P = 0.01 and P = 0.02, respectively), up-regulation of PSMB8 in HAM/TSP samples than AC and normal samples (P = 0.04 and P = 0.01, respectively), and down-regulation of TAP1 in HAM/TSP samples than those in AC and normal samples (P = 0.008 and P = 0.02, respectively). No significant difference was found among three groups in terms of the percentage of T helper and cytotoxic T lymphocytes (P = 0.55 and P = 0.12).

CONCLUSIONS

High-throughput data integration disclosed novel hub genes involved in important pathways in virus infection and immune systems. The comprehensive studies are needed to improve our knowledge about the pathogenesis pathways and also biomarkers of complex diseases.

Effects of host restriction factors and the HTLV-1 subtype on susceptibility to HTLV-1-associated myelopathy/tropical spastic paraparesis

BACKGROUND

Although human T-lymphotropic virus type 1 (HTLV-1) infection is a prerequisite for the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), specific provirus mutations in HAM/TSP have not yet been reported. In this study, we examined whether HAM/TSP patients had the disease-specific genomic variants of HTLV-1 by analyzing entire sequences of HTLV-1 proviruses in these patients, including familial cases. In addition, we investigated the genetic variants of host restriction factors conferring antiretroviral activity to determine which mutations may be related to resistance or susceptibility to HAM/TSP.

RESULTS

The subjects included 30 patients with familial HAM/TSP (f-HAM/TSP), 92 patients with sporadic HAM/TSP (s-HAM/TSP), and 89 asymptomatic HTLV-1 carriers (ACs). In all 211 samples, 37 samples (18%) were classified into transcontinental subtype and 174 samples (82%) were classified as Japanese subtype. Among three groups, the percentage of transcontinental subtype in f-HAM/TSP, s-HAM/TSP and ACs was 33, 23 and 7%, respectively. The frequency of transcontinental subtype was significantly higher in both f-HAM/TSP (p < 0.001) and s-HAM/TSP (p < 0.001) than in ACs. Fifty mutations in HTLV-1 sequences were significantly more frequent in HAM/TSP patients than in ACs, however, they were common only in transcontinental subtype. Among these mutations, ten common mutations causing amino acid changes in the HTLV-1 sequences were specific to the transcontinental subtype. We examined host restriction factors, and detected a rare variant in TRIM5α in HAM/TSP patients. The patients with TRIM5α 136Q showed lower proviral loads (PVLs) than those with 136R (354 vs. 654 copies/10⁴ PBMC, p = 0.003). The patients with the 304L variant of TRIM5α had significantly higher PVLs than those with 304H (1669 vs. 595 copies/10⁴ PBMC, p = 0.025). We could not find any HAM/TSP-specific mutations of host restriction factors.

CONCLUSIONS

Transcontinental subtype is susceptible to HAM/TSP, especially in familial cases. Ten common mutations causing amino acid changes in the HTLV-1 gene were specific to the transcontinental subtype. TRIM5α polymorphisms were associated with PVLs, indicating that TRIM5α could be implicated in HTLV-1 replication.

HTLV-1, Immune Response and Autoimmunity

Human T-lymphotropic virus type-1 (HTLV-1) infection is associated with adult T-cell leukemia/lymphoma (ATL). Tropical spastic paraparesis/HTLV-1-associated myelopathy (PET/HAM) is involved in the development of autoimmune diseases including Rheumatoid Arthritis (RA), Systemic Lupus Erythematosus (SLE), and Sjögren's Syndrome (SS). The development of HTLV-1-driven autoimmunity is hypothesized to rely on molecular mimicry, because virus-like particles can trigger an inflammatory response. However, HTLV-1 modifies the behavior of CD4⁺ T cells on infection and alters their cytokine production. A previous study showed that in patients infected with HTLV-1, the activity of regulatory CD4⁺ T cells and their consequent expression of inflammatory and anti-inflammatory cytokines are altered. In this review, we discuss the mechanisms underlying changes in cytokine release leading to the loss of tolerance and development of autoimmunity.

Familial clusters of HTLV-1-associated myelopathy/tropical spastic paraparesis

OBJECTIVE

HTLV-1 proviral loads (PVLs) and some genetic factors are reported to be associated with the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). However, there are very few reports on HAM/TSP having family history. We aimed to define the clinical features and laboratory indications associated with HAM/TSP having family history.

METHODS

Records of 784 HAM/TSP patients who were hospitalized in Kagoshima University Hospital and related hospitals from 1987 to 2012 were reviewed. Using an unmatched case-control design, 40 patients of HAM/TSP having family history (f-HAM/TSP) were compared with 124 patients suffering from sporadic HAM/TSP, who were admitted in series over the last 10 years for associated clinical features.

RESULTS

Of the 784 patients, 40 (5.1%) were f-HAM/TSP cases. Compared with sporadic cases, the age of onset was earlier (41.3 vs. 51.6 years, p<0.001), motor disability grades were lower (4.0 vs. 4.9, p = 0.043) despite longer duration of illness (14.3 vs. 10.2 years, p = 0.026), time elapsed between onset and wheelchair use in daily life was longer (18.3 vs. 10.0 years, p = 0.025), cases with rapid disease progression were fewer (10.0% vs. 28.2%, p = 0.019), and protein levels in cerebrospinal fluid (CSF) were significantly lower in f-HAM/TSP cases (29.9 vs. 42.5 mg, p<0.001). There was no difference in HTLV-1 PVLs, anti-HTLV-1 antibody titers in serum and CSF, or cell number and neopterin levels in CSF. Furthermore, HTLV-1 PVLs were lower in cases with rapid disease progression than in those with slow progression in sporadic cases [corrected]

CONCLUSIONS

We demonstrated that HAM/TSP aggregates in the family, with a younger age of onset and a slow rate of progression in f-HAM/TSP cases compared with sporadic cases. These data also suggested that factors other than HTLV-1 PVLs contribute to the disease course of HAM/TSP.

Comparison of HTLV-I Proviral Load in Adult T Cell Leukemia/Lymphoma (ATL), HTLV-I-Associated Myelopathy (HAM-TSP) and Healthy Carriers

OBJECTIVE(S)

Human T Lymphocyte Virus Type one (HTLV-I) is a retrovirus that infects about 10-20 million people worldwide. Khorasan province in Iran is an endemic area. The majority of HTLV-I-infected individuals sustain healthy carriers but small proportion of infected population developed two progressive diseases: HAM/TSP and ATL. The proviral load could be a virological marker for disease monitoring, therefore in the present study HTLV-I proviral load has been evaluated in ATL and compared to HAM/TSP and healthy carriers.

MATERIALS AND METHODS

In this case series study, 47 HTLV-I infected individuals including 13 ATL, 23 HAM/TSP and 11 asymptomatic subjects were studied. Peripheral blood mononuclear cells (PBMCs) were investigated for presence of HTLV-I DNA provirus by PCR using LTR and Tax fragments. Then in infected subjects, HTLV-I proviral load was measured using real time PCR TaqMan method.

RESULTS

The average age of patients in ATL was 52±8, in HAM/TSP 45.52±15.17 and in carrier's 38.65±14.9 years which differences were not statistically significant. The analysis of data showed a significant difference in mean WBC among study groups (ATL vs HAM/TSP and carriers P=0.0001). Moreover, mean HTLV-I proviral load was 11967.2 ± 5078, 409 ± 71.3 and 373.6 ± 143.3 in ATL, HAM/TSP and Healthy Carriers, respectively. The highest HTLV-I proviral load was measured in ATL group that had a significant correlation with WBC count (R=0.495, P=0.001). The proviral load variations between study groups was strongly significant (ATL vs carrier P=0.0001; ATL vs HAM/TSP P= 0.0001 and HAM/TSP vs carriers P< 0.05). Conclusion : The present study demonstrated that HTLV-I proviral load was higher in ATL group in comparison with HAM/TSP and healthy carriers. Therefore, HTLV-I proviral load is a prognostic factor for development of HTLV-I associated diseases and can be used as a monitoring marker for the efficiency of therapeutic regime.

The Impact of Immune Response on HTLV-I in HTLV-I-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP)

Human T lymphotropic virus type I (HTLV-I) is a retrovirus which is associated with adult T cells leukaemia (ATL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in a minority of HTLV-I-infected individuals. It is not clear why a minority of HTLV-I-infected individuals develop HAM/TSP and majority remains lifelong carriers. It seems that the interaction between the virus and the immune response plays an important role in HTLV-I-associated diseases. Although the role of the immune response in HTLV-I pathogenesis is not fully understood, however it seems that the efficacy of the immune response which is involved in controlling or limiting of viral persistence determines the outcome of HTLV-I-associated diseases. Here we discuss the role of innate and adaptive immune response and also the risk factors contribute to the observed differences between HAM/TSP patients and asymptomatic HTLV-I carriers.

The epidemiology of human retrovirus-associated illnesses

Human T-cell leukemia/lymphoma virus type 1 (HTLV-1) was the first oncogenic human retrovirus discovered in 1980. It is estimated that around 10-20 million people are infected with HTLV-1 worldwide. However, HTLV-1 is not a ubiquitous virus. Indeed, HTLV-1 is present throughout the world with clusters of high endemicity including mainly southern Japan, the Caribbean region, parts of South America and intertropical Africa, with foci in the Middle East and Australia. The origin of this puzzling geographical repartition is probably linked to a founder effect in certain human groups. In the high endemic areas, 0.5 to 50% of the people have antibodies against HTLV-1 antigens. HTLV-1 seroprevalence increases with age, especially in women. HTLV-1 has 3 modes of transmission: mother to child, mainly through prolonged breastfeeding (> 6 months); sexual, mainly but not exclusively occurring from male to female; and by blood products contaminated by infected lymphocytes. HTLV-1 is mainly the etiological agent of two very severe diseases: a malignant T CD4+ cell lymphoproliferation of very poor prognosis, named adult T-cell leukemia/lymphoma (ATLL), and a chronic neuro-myelopathy named tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). HTLV-1 is also associated with rare anterior uveitis, infective dermatitis and myositis in some high HTLV-1 endemic areas. The repartition of the different molecular subtypes or genotypes is mainly linked to the geographical origin of the infected persons but not to the associated pathology. HTLV-1 possesses a remarkable genetic stability probably linked to viral amplification via clonal expansion of infected cells rather than by reverse transcription. This stability can be used as a molecular tool to gain better insights into the origin, evolution and modes of dissemination of HTLV-1 and infected populations. HTLV-1 originated in humans through interspecies transmission from STLV-1, a very closely related retrovirus, highly endemic in several populations of apes and Old World monkeys.

No evidence for XMRV in German CFS and MS patients with fatigue despite the ability of the virus to infect human blood cells in vitro

Background

Xenotropic murine leukemia virus-related virus (XMRV), a novel human retrovirus originally identified in prostate cancer tissues, has recently been associated with chronic fatigue syndrome (CFS), a disabling disease of unknown etiology affecting millions of people worldwide. However, several subsequent studies failed to detect the virus in patients suffering from these illnesses or in healthy subjects. Here we report the results of efforts to detect antibody responses and viral sequences in samples from a cohort of German CFS and relapsing remitting multiple sclerosis (MS) patients with fatigue symptoms.

Methodology

Blood samples were taken from a cohort of 39 patients fulfilling the Fukuda/CDC criteria (CFS), from 112 patients with an established MS diagnosis and from 40 healthy donors. Fatigue severity in MS patients was assessed using the Fatigue Severity Scale (FSS). Validated Gag- and Env-ELISA assays were used to screen sera for XMRV antibodies. PHA-activated PBMC were cultured for seven days in the presence of IL-2 and DNA isolated from these cultures as well as from co-cultures of PBMC and highly permissive LNCaP cells was analyzed by nested PCR for the presence of the XMRV gag gene. In addition, PBMC cultures were exposed to 22Rv1-derived XMRV to assess infectivity and virus production.

Conclusion

None of the screened sera from CFS and MS patients or healthy blood donors tested positive for XMRV specific antibodies and all PBMC (and PBMC plus LNCaP) cultures remained negative for XMRV sequences by nested PCR. These results argue against an association between XMRV infection and CFS and MS in Germany. However, we could confirm that PBMC cultures from healthy donors and from CFS patients can be experimentally infected by XMRV, resulting in the release of low levels of transmittable virus.

Motor behavioral abnormalities and histopathological findings of Wistar rats inoculated with HTLV-1-infected MT2 cells

The objective of the present study was to describe motor behavioral changes in association with histopathological and hematological findings in Wistar rats inoculated intravenously with human T-cell lymphotropic virus type 1 (HTLV-1)-infected MT2 cells. Twenty-five 4-month-old male rats were inoculated with HTLV-1-infected MT2 cells and 13 control rats were inoculated with normal human lymphocytes. The behavior of the rats was observed before and 5, 10, 15, and 20 months after inoculation during a 30-min/rat testing time for 5 consecutive days. During each of 4 periods, a subset of rats was randomly chosen to be sacrificed in order to harvest the spinal cord for histopathological analysis and to obtain blood for serological and molecular studies. Behavioral analyses of the HTLV-1-inoculated rats showed a significant decrease of climbing, walking and freezing, and an increase of scratching, sniffing, biting, licking, and resting/sleeping. Two of the 25 HTLV-1-inoculated rats (8%) developed spastic paraparesis as a major behavioral change. The histopathological changes were few and mild, but in some cases there was diffuse lymphocyte infiltration. The minor and major behavioral changes occurred after 10-20 months of evolution. The long-term observation of Wistar rats inoculated with HTLV-1-infected MT2 cells showed major (spastic paraparesis) and minor motor abnormalities in association with the degree of HTLV-1-induced myelopathy.