HTLV-1-associated Myelopathy/tropical Spastic Paraparesis Research Articles

HTLV-1 oncovirus-host interactions: From entry to the manifestation of associated diseases.

Human T lymphotropic virus type-1 (HTLV-1) is a well-known human oncovirus, associated with two life-threatening diseases, adult T cell leukaemia/lymphoma (ATL) and HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). The study of this oncogenic virus is significant from two different aspects. First, HTLV-1 can be considered as a neglected public health problem, which may spread slowly worldwide. Second, the incidence of HTLV-1 associated diseases due to oncogenic effects and deterioration of the immune system towards autoimmune diseases are not fully understood. Furthermore, knowledge about viral routes of transmission is important for considering potential interventions, treatments or vaccines in endemic regions. In this review, novel characteristics of HTLV-1, such as the unusual infectivity of virions through the virological synapse, are discussed in the context of the HTLV-1 associated diseases (ATL and HAM/TSP).

Phenotypic and Functional Analyses Guiding Combination Immune Checkpoint Immunotherapeutic Strategies in HTLV-1 Infection.

Human T-cell lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) develops in 1–5% of HTLV-1-infected individuals. Previous studies by us and others have shown that the expression of negative immune checkpoint receptors (NCRs) is significantly increased on CD8 T cells in various chronic viral infections and are associated with poor anti-viral immunity. We have previously identified the differential expression of NCRs on CD8 T cells in blood from patients with HAM/TSP and in central nervous system (CNS) tissues of HTLV-1 infected humanized mice and defined the association with neurological complications. In this study, we determined the co-expression patterns of several key NCRs (PD-1, TIGIT, TIM-3, and LAG-3) and their cognate ligands in HTLV-1 infection and assessed how combination strategies targeting these pathways would impact HTLV-1-specific CD8 T-cell effector functions as an approach to reduce CNS disease outcomes. We found that global CD8 T cells from HAM/TSP patients co-express multiple NCRs at significantly higher frequencies than asymptomatic carriers (AC). Moreover, NCR ligands (PVR and PD-LI) on both plasmacytoid and myeloid dendritic cells were also expressed at higher frequencies in HAM/TSP compared to AC. In both AC and HAM/TSP subjects, combination dual PD-L1/TIGIT or triple PD-L1/TIGIT/TIM-3 blockade with monoclonal antibodies resulted in increases in intracellular cytokine expression in CD8 T cells after virus stimulation, particularly CD107a, a marker of degranulation, and TNF-α, a key cytokine that can directly inhibit viral replication. Interestingly, almost all blockade combinations resulted in reduced IL-2+ HTLV-1-specific CD8 T cell frequencies in HAM/TSP subjects, but not in AC. These results define a novel combinatorial NCR immunotherapeutic blockade strategy to reduce HAM/TSP disease burden.

Anti-Human T-Cell Leukemia Virus Type 1 (HTLV-1) Antibody Assays in Cerebrospinal Fluid for the Diagnosis of HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis.

The anti-human T-cell leukemia virus type 1 (HTLV-1) antibody assay in common use has changed from the particle agglutination (PA) method to chemiluminescent immunoassay (CLIA) and chemiluminescent enzyme immunoassay (CLEIA). These assays were validated in serum but not in cerebrospinal fluid (CSF). However, anti-HTLV-1 antibody positivity in CSF is a requisite for diagnosing HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). We qualitatively compared the assays in CSF from 47 HAM/TSP patients diagnosed using PA, 15 HTLV-1 carriers (HCs), and 18 negative controls. In determining the positivity or negativity of CSF anti-HTLV-1 antibodies, we used serum cutoff points for CLIA and CLEIA because CSF cutoff points had not been decided. Truth table analysis revealed that the performance of CLIA was closer to that of PA and that CLEIA had low sensitivity. CSF antibodies from HAM/TSP patients were all positive by PA and CLIA but 83.0% positive by CLEIA. CSF antibodies from HCs were positive in 73.3%, 80.0%, and 6.7% by PA, CLIA, and CLEIA, respectively. Receiver operator characteristic curve analysis for CSF revealed that with the default cutoff point used for serum, CLIA and PA had comparable performances and CLEIA was less sensitive. The best performances of CLIA and CLEIA with adjusted cutoff points were 94.8% sensitivity and 95.5% specificity and 89.7% sensitivity and 95.5% specificity, respectively. We conclude that low-sensitivity CLEIA can underdiagnose HAM/TSP and that CLIA is a better alternative to PA in anti-HTLV-1 antibody assay for CSF with the current cutoff points.

A significant association between CXCL10 -1447 A > G and IL18 -607 C > A gene polymorphism with human T-cell lymphotropic virus type 1 associated myelopathy/tropical spastic paraparesis (HAM-TSP), a case-control report from city of Mashhad, Iran.

Human T-cell lymphotropic virus type 1 (HTLV-1) is the first isolated retrovirus from humans, and 2-3% of infected individuals suffer from HTLV-1 associated myelopathy tropical spastic paraparesis (HAM-TSP). Previous studies indicated that the risk of HAM-TSP could be correlated with the individuals' genetic alterations. Mashhad is one of the areas infected with HTLV-1 in Iran. This study designed to examine the association between several important gene polymorphisms and HAM-TSP. Genotypes of 232 samples from controls, HTLV-1 carriers, and HAM-TSP patients were examined for FAS-670 (A > G), CXCL10-1447 (A > G), Foxp3-3279 (C > A), IL-18 -137 (C > G), and IL-18 -607 (C > A) gene polymorphisms by different polymerase chain reaction (PCR) techniques. A non-significant association was observed between FAS-670 A > G, Foxp3-3279 C > A, and IL-18 -137 C > G gene polymorphisms and HAM-TSP. Nevertheless, a significant (P<0.001) association between CXCL10-1447 A > G and IL-18 -607 C > A gene polymorphisms with HAM-TSP was observed in our study population. As previous studies revealed that the CXCL10 level in the cerebrospinal fluid of HAM-TSP patients was associated with the disease progression, and as we noticed, a direct association was observed between CXCL10-1447 A > G polymorphism and HAM-TSP. These polymorphisms might be recommended as a valuable prediction criterion for the severity of the disease. The contradiction between our findings and other studies regarding IL-18 -607 C > A gene polymorphism might be associated with various factors such as genotypes frequency in diverse races and population heterogeneity in the city of Mashhad.

Genome wide association study of HTLV-1–associated myelopathy/tropical spastic paraparesis in the Japanese population

HTLV-1-associated myelopathy (HAM/TSP) is a chronic and progressive inflammatory disease of the central nervous system. The aim of our study was to identify genetic determinants related to the onset of HAM/TSP in the Japanese population. We conducted a genome-wide association study comprising 753 HAM/TSP patients and 899 asymptomatic HTLV-1 carriers. We also performed comprehensive genotyping of HLA-A, -B, -C, -DPB1, -DQB1, and -DRB1 genes using next-generation sequencing technology for 651 HAM/TSP patients and 804 carriers. A strong association was observed in HLA class I (P = 1.54 × 10-9) and class II (P = 1.21 × 10-8) loci with HAM/TSP. Association analysis using HLA genotyping results showed that HLA-C*07:02 (P = 2.61 × 10-5), HLA-B*07:02 (P = 4.97 × 10-10), HLA-DRB1*01:01 (P = 1.15 × 10-9) and HLA-DQB1*05:01 (P = 2.30 × 10-9) were associated with disease risk, while HLA-B*40:06 (P = 3.03 × 10-5), HLA-DRB1*15:01 (P = 1.06 × 10-5) and HLA-DQB1*06:02 (P = 1.78 × 10-6) worked protectively. Logistic regression analysis identified amino acid position 7 in the G-BETA domain of HLA-DRB1 as strongly associated with HAM/TSP (P = 9.52 × 10-10); individuals homozygous for leucine had an associated increased risk of HAM/TSP (odds ratio, 9.57), and proline was protective (odds ratio, 0.65). Both associations were independent of the known risk associated with proviral load. DRB1-GB-7-Leu was not significantly associated with proviral load. We have identified DRB1-GB-7-Leu as a genetic risk factor for HAM/TSP development independent of proviral load. This suggests that the amino acid residue may serve as a specific marker to identify the risk of HAM/TSP even without knowledge of proviral load. In light of its allele frequency worldwide, this biomarker will likely prove useful in HTLV-1 endemic areas across the globe.

Low Annexin A1 level in HTLV-1 infected patients is a potential biomarker for the clinical progression and diagnosis of HAM/TSP

BackgroundHuman T-lymphotropic virus 1 (HTLV-1) is etiologically associated with the chronic inflammatory neurodegenerative disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) Annexin A1 (AnxA1) is an anti-inflammatory protein with proposed neuroprotective and anti-neuroinflammatory functions. We hypothesized that ANXA1 gene expression may be dysregulated in HTLV-1-infected HAM/TSP patients.MethodsThis study involved 37 individuals infected with HTLV-1, including 21 asymptomatic (AS) carriers and 16 with HAM/TSP, and a control group of 30 individuals negative for HTLV-1 and HTLV-2. For AS HTLV-1-positive and HAM/TSP patients, ANXA1 and formyl peptide receptor (FPR1, FPR2 and FPR3) expression and HTLV-1 proviral load (PVL) in peripheral blood cells were evaluated by real-time quantitative PCR (qPCR), and plasma AnxA1 levels were determined by enzyme-linked immunosorbent assay (ELISA).ResultsANXA1 gene expression was increased in the AS group compared with the HAM/TSP and control groups, but the differences were not statistically significant. FPR1 gene expression was higher in patients with HTLV-1 than in controls (AS, p = 0.0032; HAM/TSP, p < 0.0001). Plasma AnxA1 levels were higher in the AS group than in the HAM/TSP group (p = 0.0045), and PVL was higher in patients with HAM/TSP than in AS individuals (p = 0.0162). The use of a combined ROC curve using Annexin 1 levels and proviral load significantly increased the sensitivity and specificity to predict progression to HAM/TSP (AUC = 0.851 and AUC = 0.937, respectively, to AUC = 1000).ConclusionsOur results suggest that AnxA1 may be dysregulated in HAM/TSP patients. Serological detection of AnxA1 in association with proviral load may provide a prognostic biomarker for HTLV-1-associated neurodegenerative disease.

Extracellular vesicles from HTLV-1 infected cells modulate target cells and viral spread

BackgroundThe Human T-cell Lymphotropic Virus Type-1 (HTLV-1) is a blood-borne pathogen and etiological agent of Adult T-cell Leukemia/Lymphoma (ATLL) and HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP). HTLV-1 has currently infected up to 10 million globally with highly endemic areas in Japan, Africa, the Caribbean and South America. We have previously shown that Extracellular Vesicles (EVs) enhance HTLV-1 transmission by promoting cell–cell contact.ResultsHere, we separated EVs into subpopulations using differential ultracentrifugation (DUC) at speeds of 2 k (2000×g), 10 k (10,000×g), and 100 k (100,000×g) from infected cell supernatants. Proteomic analysis revealed that EVs contain the highest viral/host protein abundance in the 2 k subpopulation (2 k > 10 k > 100 k). The 2 k and 10 k populations contained viral proteins (i.e., p19 and Tax), and autophagy proteins (i.e., LC3 and p62) suggesting presence of autophagosomes as well as core histones. Interestingly, the use of 2 k EVs in an angiogenesis assay (mesenchymal stem cells + endothelial cells) caused deterioration of vascular-like-tubules. Cells commonly associated with the neurovascular unit (i.e., astrocytes, neurons, and macrophages) in the blood–brain barrier (BBB) showed that HTLV-1 EVs may induce expression of cytokines involved in migration (i.e., IL-8; 100 k > 2 k > 10 k) from astrocytes and monocyte-derived macrophages (i.e., IL-8; 2 k > 10 k). Finally, we found that EVs were able to promote cell–cell contact and viral transmission in monocytic cell-derived dendritic cell. The EVs from both 2 k and 10 k increased HTLV-1 spread in a humanized mouse model, as evidenced by an increase in proviral DNA and RNA in the Blood, Lymph Node, and Spleen.ConclusionsAltogether, these data suggest that various EV subpopulations induce cytokine expression, tissue damage, and viral spread.

Immunopathogenic CSF TCR repertoire signatures in virus-associated neurologic disease.

In this study, we examined and characterized disease-specific TCR signatures in cerebrospinal fluid (CSF) of patients with HTLV-1–associated myelopathy/tropical spastic paraparesis (HAM/TSP). TCR β libraries using unique molecular identifier–based methodologies were sequenced in paired peripheral blood mononuclear cells (PBMCs) and CSF cells from HAM/TSP patients and normal healthy donors (NDs). The sequence analysis demonstrated that TCR β repertoires in CSF of HAM/TSP patients were highly expanded and contained both TCR clonotypes shared with PBMCs and uniquely enriched within the CSF. In addition, we analyzed TCR β repertoires of highly expanded and potentially immunopathologic HTLV-1 Tax11-19–specific CD8+ T cells from PBMCs of HLA-A*0201+ HAM/TSP and identified a conserved motif (PGLAG) in the CDR3 region. Importantly, TCR β clonotypes of expanded clones in HTLV-1 Tax11-19–specific CD8+ T cells were also expanded and enriched in the CSF of the same patient. These results suggest that exploring TCR repertoires of CSF and antigen-specific T cells may provide a TCR repertoire signature in virus-associated neurologic disorders.

Human T-cell leukemia virus type 1 infection among Japanese immigrants and their descendants living in Southeast Brazil: A call for preventive and control responses.

Human T-cell leukemia virus type 1 (HTLV-1) has worldwide distribution and is considered endemic in southwestern Japan. HTLV-1 infection has been associated with adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) besides other diseases. This cross-sectional study aimed to investigate the prevalence, risk factors and molecular characterization of HTLV-1, among the world’s largest population of Japanese immigrants and their descendants outside of Japan, in São Paulo, Southeast Brazil, as well as to analyze the phylogenetic relationship among isolates of HTLV-1. From July to December 2017, 2,139 individuals from five Japanese associations were interviewed and submitted to blood collection. All serum samples were first tested for the presence of anti-HTLV-1/2 antibodies by ELISA and then peripheral blood from individuals with positive serological results were analyzed for the presence of HTLV-1 5’LTR proviral DNA. Partial sequencing of the 5’LTR region of HTLV-1 proviral DNA was performed by Sanger. The prevalence of HTLV-1 infection was 5.1% (CI 95%: 4.2–6.0). In the multiple logistic regression model, HTLV-1 infection was associated with age ≥ 45 years, female sex, being first and second-generation Japanese immigrants, and having sexual partners with history of blood transfusion. The phylogenetic analysis revealed that all HTLV-1 were classified as Cosmopolitan (1a) subtype. Of them, 47.8% were classified as Transcontinental (A) subgroup and 52.2% as belonging to the Japanese (B) subgroup. Although most HTLV-1-infected patients were asymptomatic (97.3%), blurred vision was associated with HTLV-1 infection. The high prevalence of HTLV-1 infection found in this studied population and especially the intra- and interfamily HTLV-1 transmission presents an urgent call for preventive and control responses of this infection in Brazil.

Intrinsic and Extrinsic Cell Apoptotic Pathways in Patients with HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis: A Systematic Review.

We aimed to verify the influence of intrinsic and extrinsic cell apoptotic pathways on the inhibition of cellular apoptosis in patients with tropical spastic paralysis/myelopathy related to human T cell lymphotropic virus type 1. The databases accessed were PubMed, Scopus, Science Direct, and Web of Science. Neither the time of publishing nor the language of the articles was limited. The descriptors used for this systematic literature review were: Tropical Paraparesis, Proto-Oncogenic Protein C, Bcl-2, Bcl-X Protein, Bax protein, Fas ligand (FasL) protein, Fas receptor, TNF-related apoptosis-inducing ligand and Fas-associated protein with death domain (FADD)-like apoptosis regulating. The search resulted in 546 articles from which 9 articles were selected for analysis; ranging from serum levels of Bcl-2, Fas and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) measured by enzyme-linked immunosorbent assay and the levels of cellular expression of Bcl-2 and Bcl-xL the TCD4+ lymphocytes accessed by western blot. Most studies accessed either gene expression or polymorphism of Fas, FasL, and TRAIL in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), whereas one study used flow cytometry and fluorescence to determine Fas expression. Increased Bcl-xL expression inhibited T lymphocyte apoptosis, whereas Bcl-2, serum levels, and cellular expression did not influence T lymphocyte apoptosis and serum levels of Fas were significantly higher and associated with markers of leukocyte activation in patients with HAM/TSP. In addition, Fas polymorphism (FAS-670AA) was associated with higher proviral load. There is a need for additional research on this issue since the number of patients was small and the studies presented higher heterogeneity.

Pain, psychoaffective symptoms, and quality of life in human T cell lymphotropic virus type 1 (HTLV-1): a cross-sectional study.

The objective of this study is to describe the chronic pain characteristics in individuals infected with human T cell lymphotropic virus type 1 (HTLV-1) per subgroup (asymptomatic, oligosymptomatic, and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP)) compared with controls with chronic pain without HTLV-1. This is a cross-sectional study investigating associations between pain profile, psychopathological symptoms, and quality of life. Individuals infected with HTLV-1 refer high-intensity pain compared with controls, with more severe characteristics being present in oligosymptomatic and HAM/TSP individuals. Oligosymptomatic individuals have a tendency of diffuse and frequent pain, mainly in the head/neck region and more depressive symptoms, resembling nociplastic pain. Neuropathic pain was localized in the lower limbs in all infected groups, worse in HAM/TSP individuals, and associated with a worse perception of quality of life. Pain was associated to higher levels of TNF-alpha and interferon-gamma. HTLV-1 pain is generally more severe when compared with other chronic pain syndromes, being present mainly in the lower limbs. Certain characteristics are typical, depending on the affected group. Oligosymptomatic and HAM/TSP individuals present more diffuse pain, with higher intensity and greater impact in quality of life. Increased levels of inflammatory cytokines are associated with HTLV-1-related pain.

Nanomicellar Curcumin Supplementation Improves the Clinical Manifestations of HAM/TSP Patients.

HTLV-1 infection causes a chronic, progressive, demyelinating, neuroinflammatory disease called HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Treatment of HAM/TSP patients which have high levels of proviral load and pro-inflammatory markers is a challenge for clinicians. Therefore, we aimed to investigate the immunomodulatory, anti-inflammatory, and antiviral effects of curcumin in HAM/TSP patients. In this study, 20 newly diagnosed HAM/TSP patients (2 men and 18 women) were enrolled and evaluated for clinical symptoms, HTLV-1 proviral load, Tax and HBZ expression, neopterin serum concentration, and complete blood count (CBC) before and 12weeks after treatment with nanomicellar curcumin (80mg/day, orally). Clinical symptoms such as the mean Osame Motor Disability Score and Ashworth Spasticity Scale Score were significantly improved after the treatment (P=0.001 and P=0.001). Sensory symptoms such as pain and paresthesia were significantly decreased in all of the patients (P=0.001). Furthermore, urinary disorders, including urinary frequency, incontinence, and the feeling of incomplete bladder emptying, were significantly improved (P=0.001, P=0.003, and P=0.03). However, the mean HTLV-1 proviral load (P=0.97) and CBC were similar, whereas Tax, HBZ, and neopterin levels tend to increase after the treatment (P=0.004, P=0.08, and P=0.04). Results suggest that curcumin can safely improve the clinical symptoms of HAM/TSP patients but has no observable positive effects on the HTLV-1 proviral load, Tax, and HBZ expression. Therefore, prolonged use or the use of curcumin with antiviral agents in addition to clinical signs and symptoms can reduce the HTLV-1 proviral load and the expression of functional viral factors such as Tax and HBZ.

Co-expression of HBZ, TAX and FOXp3 and HTLV-1-associated myelopathy/ tropical spastic paraparesis development in HTLV-1-infected individuals: A systematic review

Human T-cell lymphotropic virus type 1 (HTLV-1) is associated with the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). It has been reported that the HTLV-1 proteins (specifically TAX and HBZ) can modulate FOXp3, resulting in an immune imbalance that can favor the progression of HAM/TSP. This review aims to summarize the literature in order to clarify the relationship between the expression of HTLV-1 mRNAs and/or viral proteins (TAX and HBZ) with the expression of mRNA and/or protein FOXp3 and their correlation with HAM/ TSP development. This systematic review was conducted according to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis. The search strategy was performed on the Medical Literature Analysis and Retrieval System Online and Latin American and Caribbean Literature in Health Sciences Platform using subject descriptors. After screening, six articles were included in this review. The studies suggested that TAX and HBZ have a directly proportional correlation with FOXp3 in individuals with HAM/TSP, which also presented an increased expression of FOXp3 compared to asymptomatic controls and/or healthy donors. This systematic review indicates that TAX and HBZ can interact with FOXp3 and that interaction may influence HAM/ TSP development.

The E3/E4 ubiquitin conjugation factor UBE4B interacts with and ubiquitinates the HTLV-1 Tax oncoprotein to promote NF-κB activation.

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma (ATLL), and the neurological disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The HTLV-1 Tax protein persistently activates the NF-κB pathway to enhance the proliferation and survival of HTLV-1 infected T cells. Lysine 63 (K63)-linked polyubiquitination of Tax provides an important regulatory mechanism that promotes Tax-mediated interaction with the IKK complex and activation of NF-κB; however, the host proteins regulating Tax ubiquitination are largely unknown. To identify new Tax interacting proteins that may regulate its ubiquitination we conducted a yeast two-hybrid screen using Tax as bait. This screen yielded the E3/E4 ubiquitin conjugation factor UBE4B as a novel binding partner for Tax. Here, we confirmed the interaction between Tax and UBE4B in mammalian cells by co-immunoprecipitation assays and demonstrated colocalization by proximity ligation assay and confocal microscopy. Overexpression of UBE4B specifically enhanced Tax-induced NF-κB activation, whereas knockdown of UBE4B impaired Tax-induced NF-κB activation and the induction of NF-κB target genes in T cells and ATLL cell lines. Furthermore, depletion of UBE4B with shRNA resulted in apoptotic cell death and diminished the proliferation of ATLL cell lines. Finally, overexpression of UBE4B enhanced Tax polyubiquitination, and knockdown or CRISPR/Cas9-mediated knockout of UBE4B attenuated both K48- and K63-linked polyubiquitination of Tax. Collectively, these results implicate UBE4B in HTLV-1 Tax polyubiquitination and downstream NF-κB activation.

Immunopathogenesis and Cellular Interactions in Human T-Cell Leukemia Virus Type 1 Associated Myelopathy/Tropical Spastic Paraparesis

HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) is a neuropathological disorder in 1–3% of individuals infected with Human T-lymphotropic virus 1 (HTLV-1). This condition is characterized by progressive spastic lower limb weakness and paralysis, lower back pain, bladder incontinence, and mild sensory disturbances resembling spinal forms of multiple sclerosis. This disease also causes chronic disability and is therefore associated with high health burden in areas where HTLV-1 infection is endemic. Despite various efforts in understanding the virus and discovery of novel diagnostic markers, and cellular and viral interactions, HAM/TSP management is still unsatisfactory and mainly focused on symptomatic alleviation, and it hasn’t been explained why only a minority of the virus carriers develop HAM/TSP. This comprehensive review focuses on host and viral factors in association with immunopathology of the disease in hope of providing new insights for drug therapies or other forms of intervention.

Extracellular Vesicles in HTLV-1 Communication: The Story of an Invisible Messenger

Human T-cell lymphotropic virus type 1 (HTLV-1) infects 5–10 million people worldwide and is the causative agent of adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) as well as other inflammatory diseases. A major concern is that the most majority of individuals with HTLV-1 are asymptomatic carriers and that there is limited global attention by health care officials, setting up potential conditions for increased viral spread. HTLV-1 transmission occurs primarily through sexual intercourse, blood transfusion, intravenous drug usage, and breast feeding. Currently, there is no cure for HTLV-1 infection and only limited treatment options exist, such as class I interferons (IFN) and Zidovudine (AZT), with poor prognosis. Recently, small membrane-bound structures, known as extracellular vesicles (EVs), have received increased attention due to their potential to carry viral cargo (RNA and proteins) in multiple pathogenic infections (i.e., human immunodeficiency virus type I (HIV-1), Zika virus, and HTLV-1). In the case of HTLV-1, EVs isolated from the peripheral blood and cerebral spinal fluid (CSF) of HAM/TSP patients contained the viral transactivator protein Tax. Additionally, EVs derived from HTLV-1-infected cells (HTLV-1 EVs) promote functional effects such as cell aggregation which enhance viral spread. In this review, we present current knowledge surrounding EVs and their potential role as immune-modulating agents in cancer and other infectious diseases such as HTLV-1 and HIV-1. We discuss various features of EVs that make them prime targets for possible vehicles of future diagnostics and therapies.

Decrease in naïve T cell production due to HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) development

Human T-lymphocytic virus 1 (HTLV-1) is mainly associated with adult T-cell leukemia/lymphoma (ATLL) and HTLV-1–associated myelopathy/tropical spastic paraparesis (HAM/TSP). Patients with HAM/TSP exhibit significant changes in their immune response, and HTLV-1 infection can interfere in cytokine production and perhaps in T cell production. The aims of this study were to evaluate thymic function in HAM/TSP patients and HTLV-1 healthy carriers (HCs) and correlate it to age and interleukin 7 (IL-7) gene expression. Thymic function in 21 HAM/TSP patients and 12 HCs was evaluated by quantifying T cell receptor rearrangement excision circle (TREC) particles and IL-7 gene expression, both measured by quantitative polymerase chain reaction. HAM/TSP patients presented lower TREC particle counts (p = 0.0112) and lower IL-7 expression (p = 0.0102) than HCs. Both TREC particles and IL-7 gene expression were separately analyzed in two age groups: ≤ 59 years and ≥60 years, The ≤59-year-old HAM/TSP patients had a lower TREC count compared with the ≤59-year-old HCs (p = 0.0476). In conclusion, HAM/TSP development could interfere with thymic function because the results showed TREC particle reduction in HAM/TSP patients in relation to HCs, and it could be associated with a concomitant reduction in IL-7 expression.

17454 Leveraging CRISPR-Cas12a for the detection of human T-Cell leukemia virus type 1

Human T-cell leukemia virus type 1 (HTLV-1) is a potent carcinogenic oncovirus that, while asymptomatic in the majority, has the potential to cause devastating complications such as adult T-cell leukemia/lymphoma (ATLL) or HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Despite its high morbidity and global burden, poor access to current testing modalities limits HTLV-1 testing in endemic regions. Here we perform the pre-clinical, proof-of-concept experiments necessary for the development of a sensitive, specific, and low-cost CRISPR-based screening test for HTLV-1. We took advantage of recent reports describing the ability of Cas12a enzymes and guide RNAs (gRNAs) to act as molecular sensors in field-deployable viral diagnostic assays. Upon specific recognition of the gRNA-complementary DNA sequence, eg HTLV-1 proviral DNA, Cas12a/gRNA complexes can catalyze nonspecific trans-cleavage of a single-stranded DNA (ssDNA) reporter, providing an amplified signal of the target recognition event (2). We designed and synthesized multiple HTLV-1-specific Cas12a gRNAs targeted to conserved regions of the HTLV-1 genome. We also designed a custom ssDNA reporter molecule that could be used to measure target-induced Cas12a trans-cleavage activity by quantitative polymerase chain reaction (qPCR). Upon detection of HTLV-1-specific targets in vitro, Cas12/gRNA complexes demonstrated concentration-dependent cleavage of ssDNA. Our assay was able to detect 36 femtomoles of HTLV-1 target DNA and lays the foundation for future efforts to develop a robust, point-of-care CRISPR-based HTLV-1 diagnostic test that could potentially transform the detection and management of HTLV-1 infection.

Dietary Intake and Serum Selenium Levels Influence the Outcome of HTLV-1 Infection.

Human T cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP), as the most common neurological emersion related to HTLV-1, is a debilitating and lifelong treating disease with no definitive treatment. Furthermore, it has been determined that dietary compositions (inflammatory and anti-inflammatory) and some micronutrients (such as vitamin D and selenium) have an effect on inflammatory and immune processes and with this background; the study was done to compare the nutritional status between age- and sex-matched with infected and non-infected HTLV-1. In a multi-center setting, 70 healthy controls (HCs), 35 asymptomatic carriers (ACs), and 35 HAM/TSP patients were recruited in the HTLV-1 Foundation, Ghaem Hospital, Mashhad University of Medical Sciences, Mashhad, Iran. Nutritional status including anthropometric indices, dietary (micro- and macronutrient) intake, and serum vitamin D, vitamin B12, zinc, and selenium were measured. In anthropometric indices, mean waist circumference (WC) in the carrier group was significantly higher than the patient and the control groups (p = 0.008). In the dietary intake, the patient group received less energy, protein, mono-unsaturated fatty acids (MUFA), and oleic, but more fat than the HTLV-1 carrier and control groups, and these differences were remarkable in three groups (p = 0.002, 0.005, 0.001, 0.01, and 0.001, respectively), whereas the carrier group received more saturated fatty acid and less poly-unsaturated fatty acids (PUFA), linoleic, and linolenic than patient and control groups with a different significant (p = 0.01, 0.007, 0.005, and 0.006, respectively) in three groups. In micronutrient intake, although selenium, zinc, and vitamins B12 and D were lower in the patient group than the carrier and control group, however, no significant differences were observed. In comparison with micronutrient serum concentrations, vitamins B12 and D and selenium in the patient group were lower than the carrier and control groups, but statistically, the considerable difference was found only in the selenium concentration (p = 0.001). The study showed that there were differences in dietary intake (including energy, macronutrients, and fatty acids), WC, and selenium serum levels between HAM/TSP patients and HTLV-1 carriers, suggesting that nutritional statues influence the inflammatory immune response in HTLV-1 infection.

Health state utility values in people living with HTLV-1 and in patients with HAM/TSP: The impact of a neglected disease on the quality of life.

Background: HTLV-1 is a neglected sexually transmitted infection despite being the cause of disabling neurological disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). There is no treatment for this infection and public health policies are essential to reduce its transmission. However, there are no data to support adequate cost-effective analysis in this field. The aim of this study was to obtain health state utility values for individuals with HAM/TSP and HTLV-1 asymptomatic carriers (AC). The impact of both states on quality of life (QoL) is described and compared to other diseases. Methods: A cross-sectional observational study of 141 individuals infected with HTLV-1 (79 with HAM/TSP and 62 AC) from three Brazilian states (Rio de Janeiro, São Paulo and Alagoas) and from the United Kingdom. Participants completed a validated general health questionnaire (EQ-5D, Euroqol) from which country specific health state utility values are generated. Clinical and epidemiological data were collated. Principal findings: Health state utility value for HAM/TSP was 0.2991. QoL for 130 reported clinical conditions ranges from 0.35 to 0.847. 12% reported their quality of life as worse as death. Low QoL was associated with severity rather than duration of disease with a moderate inverse correlation between QoL and Osame’s Motor Disability Score (-0.4933) Patients who are wheelchair dependent had lowest QoL whilst those still walking unaided had the highest. AC also reported impaired QoL (0.7121) compared to general population. Conclusion: HTLV-1 and its associated neurological disease has a marked impact on QoL. This study provides robust data to support the development of cost-utility analysis of interventions for HTLV-1.