Novel paired CD13-negative (MT-50.1) and CD13-positive (MT-50.4) HTLV-1-infected T-cell lines with differential regulatory T cell-like activity.

Adult T-cell leukemia/lymphoma (ATL) occurs after human T-cell leukemia virus type-1 (HTLV-1) infection with a long latency period exceeding several decades. This implies the presence of immune evasion mechanisms for HTLV-1-infected T cells. Although ATL cells have a CD4+CD25+ phenotype similar to that of regulatory T cells (Tregs), they do not always possess the immunosuppressive functions of Tregs. Factors that impart effective immunosuppressive functions to HTLV-1-infected cells may exist. A previous study identified a new CD13+ Treg subpopulation with enhanced immunosuppressive activity. We, herein, describe the paired CD13- (designated as MT-50.1) and CD13+ (MT-50.4) HTLV-1-infected T-cell lines with Treg-like phenotype, derived from the peripheral blood of a single patient with lymphoma-type ATL. The cell lines were found to be derived from HTLV-1-infected non-leukemic cells. MT-50.4 cells secreted higher levels of immunosuppressive cytokines, IL-10 and TGF-ß, expressed higher levels of Foxp3, and showed stronger suppression of CD4+CD25- T cell proliferation than MT-50.1 cells. Furthermore, the CD13 inhibitor bestatin significantly attenuated MT-50.4 cell growth, while it did not for MT-50.1 cells. These findings suggest that CD13 expression may be involved in the increased Treg-like activity of MT-50.4 cells. Hence, MT-50.4 cells will be useful for in-depth studies of CD13+Foxp3+ HTLV-1-infected cells.

Prevalence of HTLV-1/2 infection in pregnant women in Central and South America and the Caribbean: a systematic review and meta-analysis.

BACKGROUND: Human T-lymphotropic viruses (HTLV)-1 infection is endemic in many countries of Central and South America and Caribbean (CSA&C). Neither screening nor surveillance programs exist for HTLV-1/2 infection among pregnant women in this region. Neither in Western nations with large migrant flows from HTLV-1/2 endemic regions. METHODS: Systematic review and meta-analysis of the prevalence of HTLV-1/2 infection among CSA&C pregnant women. We included studies searching EMBASE, PubMed/MEDLINE, Scopus, and Web of Science from inception to February 15, 2023. This systematic review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines. RESULTS: We identified a total of 620 studies. Only 41 were finally included in the meta-analysis. Most studies (61.0%) were from Brazil and Peru (14.6%). The total number of participants was 343,707. The pooled prevalence of HTLV-1/2 infection among CSA&C pregnant women was 1.30% (95% CI: 0.96-1.69) using anti-HTLV-1/2 antibody screening tests. There was a high heterogeneity (I2 = 98.6%). Confirmatory tests gave an HTLV-1 infection rate of 1.02% (95% CI: 0.75-1.33). CONCLUSIONS: The prevalence of HTLV-1/2 infection among CSA&C pregnant women is 1.3%, most cases being HTLV-1. This rate is greater than for other microbial agents regularly checked as part of antenatal screening (such as HIV, hepatitis B, or syphilis). Thus, HTLV-1/2 antenatal testing should be mandatory among CSA&C pregnant women everywhere.

Potential role of HTLV-1 Tax-specific cytotoxic t lymphocytes expressing a unique t-cell receptor to promote inflammation of the central nervous system in myelopathy associated with HTLV-1.

Human T-lymphotropic virus 1 (HTLV-1) infection causes two serious diseases: adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy (HAM). Immunological studies have revealed that HTLV-1 Tax-specific CD8+ cytotoxic T-cells (Tax-CTLs) in asymptomatic carriers (ACs) and ATL patients play an important role in the elimination of HTLV-1-infected host cells, whereas Tax-CTLs in HAM patients trigger an excessive immune response against HTLV-1-infected host cells infiltrating the central nervous system (CNS), leading to local inflammation. Our previous evaluation of HTLV-1 Tax301-309 (SFHSLHLLF)-specific Tax-CTLs (Tax301-309-CTLs) revealed that a unique T-cell receptor (TCR) containing amino acid (AA)-sequence motif PDR, was shared among HLA-A*24:02+ ACs and ATL patients and behaved as an eliminator by strong activity against HTLV-1. However, it remains unclear whether PDR+Tax301-309-CTLs also exist in HLA-A*24:02+ HAM patients and are involved in the pathogenesis of HAM. In the present study, by high-throughput TCR repertoire analysis technology, we revealed TCR repertoires of Tax301-309-CTLs in peripheral blood (PB) of HLA-A*24:02+ HAM patients were skewed, and a unique TCR-motif PDR was conserved in HAM patients (10 of 11 cases). The remaining case dominantly expressed (-DR, P-R, and PD-), which differed by one AA from PDR. Overall, TCRs with unique AA-sequence motifs PDR, or (-DR, P-R, and PD-) accounted for a total of 0.3-98.1% of Tax301-309-CTLs repertoires of HLA-A*24:02+ HAM patients. Moreover, TCR repertoire analysis of T-cells in the cerebrospinal fluid (CSF) from four HAM patients demonstrated the possibility that PDR+Tax301-309-CTLs and (-DR, P-R, and PD-)+Tax301-309-CTLs efficiently migrated and accumulated in the CSF of HAM patients fostering increased inflammation, although we observed no clear significant correlation between the frequencies of them in PB and the levels of CSF neopterin, a known disease activity biomarker of HAM. Furthermore, to better understand the potential function of PDR+Tax301-309-CTLs, we performed immune profiling by single-cell RNA-sequencing of Tax301-309-CTLs, and the result showed that PDR+Tax301-309-CTLs up-regulated the gene expression of natural killer cell marker KLRB1 (CD161), which may be associated with T-cell activation and highly cytotoxic potential of memory T-cells. These findings indicated that unique and shared PDR+Tax301-309-CTLs have a potential role in promoting local inflammation within the CNS of HAM patients.

HTLV-1 infection promotes excessive T cell activation and transformation into adult T cell leukemia/lymphoma.

Human T cell leukemia virus type 1 (HTLV-1) mainly infects CD4+ T cells and induces chronic, persistent infection in infected individuals, with some developing adult T cell leukemia/lymphoma (ATL). HTLV-1 alters cellular differentiation, activation, and survival; however, it is unknown whether and how these changes contribute to the malignant transformation of infected cells. In this study, we used single-cell RNA-sequencing and T cell receptor-sequencing to investigate the differentiation and HTLV-1-mediated transformation of T cells. We analyzed 87,742 PBMCs from 12 infected and 3 uninfected individuals. Using multiple independent bioinformatics methods, we demonstrated the seamless transition of naive T cells into activated T cells, whereby HTLV-1-infected cells in an activated state further transformed into ATL cells, which are characterized as clonally expanded, highly activated T cells. Notably, the greater the activation state of ATL cells, the more they acquire Treg signatures. Intriguingly, the expression of HLA class II genes in HTLV-1-infected cells was uniquely induced by the viral protein Tax and further upregulated in ATL cells. Functional assays revealed that HTLV-1-infected cells upregulated HLA class II molecules and acted as tolerogenic antigen-presenting cells to induce anergy of antigen-specific T cells. In conclusion, our study revealed the in vivo mechanisms of HTLV-1-mediated transformation and immune escape at the single-cell level.

A novel high performing multiplex immunoassay Multi-HTLV for serological confirmation and typing of HTLV infections.

BACKGROUND: Human T-Cell Lymphotropic Viruses (HTLV) type 1 and type 2 account for an estimated 5 to 10 million infections worldwide and are transmitted through breast feeding, sexual contacts and contaminated cellular blood components. HTLV-associated syndromes are considered as neglected diseases for which there are no vaccines or therapies available, making it particularly important to ensure the best possible diagnosis to enable proper counselling of infected persons and avoid secondary transmission. Although high quality antibody screening assays are available, currently available confirmatory tests are costly and have variable performance, with high rates of indeterminate and non-typable results reported in many regions of the world. The objective of this project was to develop and validate a new high-performance multiplex immunoassay for confirmation and discrimination of HTLV-1 and HTLV-2 strains. METHODOLOGY/PRINCIPAL FINDINGS: The multiplex platform was used first as a tool to identify suitable antigens and in a second step for assay development. With data generated on over 400 HTLV-positive blood donors sourced from USA and French blood banks, we developed and validated a high-precision interpretation algorithm. The Multi-HTLV assay demonstrated very high performance for confirmation and strain discrimination with 100% sensitivity, 98.1% specificity and 100% of typing accuracy in validation samples. The assay can be interpreted either visually or automatically with a colorimetric image reader and custom algorithm, providing highly reliable results. CONCLUSIONS/SIGNIFICANCE: The newly developed Multi-HTLV is very competitive with currently used confirmatory assays and reduces considerably the number of indeterminate results. The multiparametric nature of the assay opens new avenues to study specific serological signatures of each patient, follow the evolution of infection, and explore utility for HTLV disease prognosis. Improving HTLV diagnostic testing will be critical to reduce transmission and to improve monitoring of seropositive patients.

Early Effects of HTLV-1 Infection on the Activation, Exhaustion, and Differentiation of T-Cells in Humanized NSG Mice.

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive malignancy of CD4+ T-cells associated with HTLV-1 infection. In this study, we used the model of immunodeficient NSG mice reconstituted with a functional human immune system (HIS) to investigate early events in HTLV-1 pathogenesis. Upon infection, human T-cells rapidly increased in the blood and lymphoid tissues, particularly CD4+CD25+ T-cells. Proliferation of CD4+ T-cells in the spleen and mesenteric lymph nodes (MLN) correlated with HTLV-1 proviral load and CD25 expression. In addition, splenomegaly, a common feature of ATLL in humans, was also observed. CD4+ and CD8+ T-cells predominantly displayed an effector memory phenotype (CD45RA-CCR7-) and expressed CXCR3 and CCR5 chemokine receptors, suggesting the polarization into a Th1 phenotype. Activated CD8+ T-cells expressed granzyme B and perforin; however, the interferon-γ response by these cells was limited, possibly due to elevated PD-1 expression and increased frequency of CD4+FoxP3+ regulatory T-cells in MLN. Thus, HTLV-1-infected HIS-NSG mice reproduced several characteristics of infection in humans, and it may be helpful to investigate ATLL-related events and to perform preclinical studies. Moreover, aspects of chronic infection were already present at early stages in this experimental model. Collectively, we suggest that HTLV-1 infection modulates host immune responses to favor viral persistence.

An Epitope Platform for Safe and Effective HTLV-1-Immunization: Potential Applications for mRNA and Peptide-Based Vaccines.

Human T-cell lymphotropic virus type 1 (HTLV-1) infection affects millions of individuals worldwide and can lead to severe leukemia, myelopathy/tropical spastic paraparesis, and numerous other disorders. Pursuing a safe and effective immunotherapeutic approach, we compared the viral polyprotein and the human proteome with a sliding window approach in order to identify oligopeptide sequences unique to the virus. The immunological relevance of the viral unique oligopeptides was assessed by searching them in the immune epitope database (IEDB). We found that HTLV-1 has 15 peptide stretches each consisting of uniquely viral non-human pentapeptides which are ideal candidate for a safe and effective anti-HTLV-1 vaccine. Indeed, experimentally validated HTLV-1 epitopes, as retrieved from the IEDB, contain peptide sequences also present in a vast number of human proteins, thus potentially instituting the basis for cross-reactions. We found a potential for cross-reactivity between the virus and the human proteome and described an epitope platform to be used in order to avoid it, thus obtaining effective, specific, and safe immunization. Potential advantages for mRNA and peptide-based vaccine formulations are discussed.

Impact of HIV co-infection on immunological biomarker profile of HTLV-1 infected patients.

The impact of HIV co-infection on the plasma immunological biomarker profile of HTLV-1 infected patients was evaluated. The plasma levels of leukotrienes and chemokines/cytokines were quantified by ELISA and Cytometric Bead Array. A total of 138 volunteers were enrolled and divided into two subgroups ("HTLV-1(+)HIV(-)" and "HTLV-1(+)(HIV(+)"), which were categorized according to the HTLV-1-associated neurological disease (AS, pHAM and HAM). Reference controls were BD and HIV mono-infected patients. HAM(+) exhibited higher CD4+ T-cell counts as compared to HIV+ mono-infected patients and lower HTLV-1 proviral load as compared to mono-infected HAM(-) patients. AS(+) exhibited higher levels of CysLT, CXCL8/IL-8 and lower levels of CCL5/RANTES as compared to AS(-). Increased levels of IL-6 and TNF with reduced levels of CXCL10/IP10 and CCL5/RANTES were observed in co-infected pHAM(+) as compared to mono-infected pHAM(-). HAM(+) patients revealed an increase in CXCL8/IL-8, CCL2/MCP-1, CXCL-10/IP-10, TNF and a decrease in IL-2 as compared to HAM(-) subgroup.

Association of human T-cell leukemia virus type 1 with prevalent rheumatoid arthritis among atomic bomb survivors: A cross-sectional study.

ABSTRACT: Previous studies have suggested that human T-cell leukemia virus type 1 (HTLV-1) might act as a pathogen in rheumatoid arthritis (RA), but epidemiological evidence of an association is scarce. We measured anti-HTLV-1 antibodies among Nagasaki atomic bomb survivors to determine whether HTLV-1 is related to RA and whether radiation exposure is associated with HTLV-1 and RA prevalence.This is a cross-sectional study among atomic bomb survivors who participated in biennial health examinations from 2006 to 2010. Serum levels of anti-HTLV-1 antibodies were measured using a chemiluminescent enzyme immunoassay and confirmed by Western blotting. Association between HTLV-1 and RA was analyzed by a logistic regression model.Of 2091 participants (women 61.5%; median age, 73 years), 215 (10.3%) had anti-HTLV-1 antibodies. HTLV-1 prevalence was higher among women (13.1% vs 5.8%; P < .001). Twenty-two participants (1.1%) were diagnosed with RA. HTLV-1 prevalence among RA participants was significantly higher than that among non-RA participants (27.3% vs 10.1%; P = .020). After adjustment for age, sex, and hepatitis C virus infection, HTLV-1 was significantly associated with prevalent RA (odds ratio, 2.89; 95% confidence interval, 1.06, 7.03). There was no association between radiation dose and either the prevalence of HTLV-1 or RA.This study, among a well-defined group of atomic bomb survivors, suggests that HTLV-1 is associated with RA.

Latency Reversing Agents: Kick and Kill of HTLV-1?

Human T-cell leukemia virus type 1 (HTLV-1), the cause of adult T-cell leukemia/lymphoma (ATLL), is a retrovirus, which integrates into the host genome and persistently infects CD4+ T-cells. Virus propagation is stimulated by (1) clonal expansion of infected cells and (2) de novo infection. Viral gene expression is induced by the transactivator protein Tax, which recruits host factors like positive transcription elongation factor b (P-TEFb) to the viral promoter. Since HTLV-1 gene expression is repressed in vivo by viral, cellular, and epigenetic mechanisms in late phases of infection, HTLV-1 avoids an efficient CD8+ cytotoxic T-cell (CTL) response directed against the immunodominant viral Tax antigen. Hence, therapeutic strategies using latency reversing agents (LRAs) sought to transiently activate viral gene expression and antigen presentation of Tax to enhance CTL responses towards HTLV-1, and thus, to expose the latent HTLV-1 reservoir to immune destruction. Here, we review strategies that aimed at enhancing Tax expression and Tax-specific CTL responses to interfere with HTLV-1 latency. Further, we provide an overview of LRAs including (1) histone deacetylase inhibitors (HDACi) and (2) activators of P-TEFb, that have mainly been studied in context of human immunodeficiency virus (HIV), but which may also be powerful in the context of HTLV-1.

Epitope-based universal vaccine for Human T-lymphotropic virus-1 (HTLV-1).

Human T-cell leukemia virus type 1 (HTLV-1) was the first oncogenic human retrovirus identified in humans which infects at least 10-15 million people worldwide. Large HTLV-1 endemic areas exist in Southern Japan, the Caribbean, Central and South America, the Middle East, Melanesia, and equatorial regions of Africa. HTLV-1 TAX viral protein is thought to play a critical role in HTLV-1 associated diseases. We have used numerous bio-informatics and immuno-informatics implements comprising sequence and construction tools for the construction of a 3D model and epitope prediction for HTLV-1 Tax viral protein. The conformational linear B-cell and T-cell epitopes for HTLV-1 TAX viral protein have been predicted for their possible collective use as vaccine candidates. Based on in silico investigation two B cell epitopes, KEADDNDHEPQISPGGLEPPSEKHFR and DGTPMISGPCPKDGQPS spanning from 324-349 and 252-268 respectively; and T cell epitopes, LLFGYPVYV, ITWPLLPHV and GLLPFHSTL ranging from 11-19, 163-171 and 233-241 were found most antigenic and immunogenic epitopes. Among different vaccine constructs generated by different combinations of these epitopes our predicted vaccine construct was found to be most antigenic with a score of 0.57. T cell epitopes interacted strongly with HLA-A*0201 suggesting a significant immune response evoked by these epitopes. Molecular docking study also showed a high binding affinity of the vaccine construct for TLR4. The study was carried out to predict antigenic determinants of the Tax protein along with the 3D protein modeling. The study revealed a potential multi epitope vaccine that can raise the desired immune response against HTLV-1 and be useful in developing effective vaccines against Human T-lymphotropic virus.

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.

In vivo dynamics and adaptation of HTLV-1-infected clones under different clinical conditions.

Human T-cell leukemia virus type 1 (HTLV-1) spreads through cell contact. Therefore, this virus persists and propagates within the host by two routes: clonal proliferation of infected cells and de novo infection. The proliferation is influenced by the host immune responses and expression of viral genes. However, the detailed mechanisms that control clonal expansion of infected cells remain to be elucidated. In this study, we show that newly infected clones were strongly suppressed, and then stable clones were selected, in a patient who was infected by live liver transplantation from a seropositive donor. Conversely, most HTLV-1+ clones persisted in patients who received hematopoietic stem cell transplantation from seropositive donors. To clarify the role of cell-mediated immunity in this clonal selection, we suppressed CD8+ or CD16+ cells in simian T-cell leukemia virus type 1 (STLV-1)-infected Japanese macaques. Decreasing CD8+ T cells had marginal effects on proviral load (PVL). However, the clonality of infected cells changed after depletion of CD8+ T cells. Consistent with this, PVL at 24 hours in vitro culture increased, suggesting that infected cells with higher proliferative ability increased. Analyses of provirus in a patient who received Tax-peptide pulsed dendritic cells indicate that enhanced anti-Tax immunity did not result in a decreased PVL although it inhibited recurrence of ATL. We postulate that in vivo selection, due to the immune response, cytopathic effects of HTLV-1 and intrinsic attributes of infected cells, results in the emergence of clones of HTLV-1-infected T cells that proliferate with minimized HTLV-1 antigen expression.

Short-term cultured autologous peripheral blood mononuclear cells as a potential immunogen to activate Tax-specific CTL response in adult T-cell leukemia patients.

Activation of CD8+ Tax-specific CTL is a new therapeutic concept for adult T-cell leukemia (ATL) caused by HTLV-1. A recent clinical study of the dendritic cell vaccine pulsed with Tax peptides corresponding to CTL epitopes showed promising outcomes in ATL patients possessing limited human leukocyte antigen (HLA) alleles. In this study, we aimed to develop another immunotherapy to activate Tax-specific CTL without HLA limitation by using patients' own HTLV-1-infected cells as a vaccine. To examine the potential of HTLV-1-infected T-cells to activate CTL via antigen presenting cells, we established a unique co-culture system. We demonstrated that mitomycin C-treated HLA-A2-negative HTLV-1-infected T-cell lines or short-term cultured peripheral blood mononuclear cells (PBMC) derived from ATL patients induced cross-presentation of Tax antigen in co-cultured HLA-A2-positive antigen presenting cells, resulting in activation of HLA-A2-restricted CD8+ Tax-specific CTL. This effect was not inhibited by a reverse transcriptase inhibitor. IL-12 production and CD86 expression were also induced in antigen presenting cells co-cultured with HTLV-1-infected cells at various levels, which were improved by pre-treatment of the infected cells with histone deacetylase inhibitors. Furthermore, monocyte-derived dendritic cells induced from PBMC of a chronic ATL patient produced IL-12 and expressed enhanced levels of CD86 when co-cultured with autologous lymphocytes that had been isolated from the same PBMC and cultured for several days. These findings suggest that short-term cultured autologous PBMC from ATL patients could potentially serve as a vaccine to evoke Tax-specific CTL responses.

Seroprevalence of human T-lymphotropic virus infection among blood donors in China: a first nationwide survey.

BACKGROUND: So far, the prevalence of human T-lymphotropic virus (HTLV) type 1 and 2 in some highly populated countries such as China is still unknown. In this study, a multi-center nationwide serological survey was designed and performed, to reveal the seroprevalence of HTLV infection among Chinese blood donors. RESULTS: Among 8,411,469 blood donors from 155 blood establishments, 435 were finally confirmed as HTLV carriers. The prevalence of HTLV infection in China varied in different provinces: Fujian had the highest prevalence of 36.240/100,000 (95% CI 31.990-41.050) and eleven provinces did not find HTLV-seropositive donors in the three years. no HTLV-2 infection was found. The overall prevalence of HTLV-1 in China decreased from 2016 to 2018. Female was identified as an independent risk factor of HTLV infection in China. Besides, seroconversion was observed in two of seven seroindeterminate donors 85 and 250 days after their last donation, respectively. CONCLUSIONS: The seroprevalence of HTLV infection in most areas of China among blood donors is quite low, but it varies significantly in different geographic areas. Screening anti-HTLV-1/2 antibody and follow-up of serointederminate donors are essential to ensure blood safety especially in areas where we have found HTLV infected donors.

Human T-cell leukaemia virus type 1 associated pulmonary disease: clinical and pathological features of an under-recognised complication of HTLV-1 infection.

The lung is one of several organs that can be affected by HTLV-1 mediated inflammation. Pulmonary inflammation associated with HTLV-1 infection involves the interstitium, airways and alveoli, resulting in several clinical entities including interstitial pneumonias, bronchiolitis and alveolitis, depending on which structures are most affected. Augmentation of the inflammatory effects of HTLV-1 infected lymphocytes by recruitment of other inflammatory cells in a positive feedback loop is likely to underlie the pathogenesis of HTLV-1 associated pulmonary disease, as has been proposed for HTLV-1 associated myelopathy. In contrast to the conclusions of early case series, HTLV-1 associated pulmonary disease can be associated with significant parenchymal damage, which may progress to bronchiectasis where this involves the airways. Based on our current understanding of HTLV-1 associated pulmonary disease, diagnostic criteria are proposed.

Estimation of the window period of human T-cell leukemia virus type 1 and 2 tests by a lookback study of seroconverters among Japanese voluntary blood donors.

BACKGROUND: Japan is endemic for human T-cell leukemia virus type 1 (HTLV-1), and the horizontal transmission of HTLV-1 is often reported. However, the window period (WP) for serologic or molecular screening is unclear. STUDY DESIGN AND METHODS: Results for anti-HTLV-1 screening and confirmatory tests obtained from 648 591 repeated blood donors in the Kyushu district, one of the most endemic areas of HTLV-1 in the world, were evaluated. A lookback study was conducted for seroconverters. RESULTS: During 2012 to 2019, 436 seroconverters (155 men, 281women) were identified with use of a screening chemiluminescence enzyme-immunoassay (CLEIA) and multiple confirmatory tests. Because the period between the latest seronegative donation and seroconversion was highly variable (2.1-276.7 months), 19 cases that seroconverted within 6 months were subjected to the analysis. The WP of the particle agglutination assay and CLEIA was estimated to be 2.2 ± 0.6 and 2.6 ± 1.7 months, respectively. The WP of the indirect immunofluorescence assay was 4.8 ± 6.5 months. Although the WP of western blotting was estimated to be 6.3 ± 8.7 months, four cases were still indeterminate through the study period. Chemiluminescence and line immunoassays, the current screening and confirmatory tests used in the Japanese blood program, showed the shortest WP of 2.2 ± 0.6 months. The WP of real-time polymerase chain reaction for HTLV-1 was estimated to be 4.1 ± 7.8 months. CONCLUSIONS: The WP in commercially available testing systems for HTLV-1/2 was determined for natural infection among repeated blood donors. Considering the HTLV-1 WP will help increase transfusion safety and facilitate the accurate diagnosis of HTLV-1 infection.

Adult T-cell leukemia/lymphoma clinically confused with viral/drug skin eruptions and pathologically misinterpreted as mycosis fungoides/Sézary syndrome.

Adult T-cell leukemia/lymphoma (ATLL) is a lymphoproliferative disorder of mature CD4-positive T-cell lymphoid cells associated with retrovirus human T-lymphotropic virus type-1 (HTLV-1) with a wide clinical and pathologic spectrum. We report a case of a 53-year-old African man who presented with fever and skin eruptions on the trunk composed of non-itchy erythematous reticulated macules and papules initially suspected for viral exanthem or drug rash. Skin punch biopsy showed a dermal T-cell lymphoid infiltrate with epidermotropism. The patient developed generalized lymphadenopathy and his peripheral blood showed lymphocytosis with atypical lymphocytes with convoluted nuclei. Our initial diagnosis was mycosis fungoides with Sézary syndrome. However, some clinical and histopathologic features were unusual. The acute onset, lack of previous skin lesions, the histomorphologic features of the dermal, nodal and peripheral blood lymphocytes and the geographic origin of the patient raised the suspicion of other T-cell lymphomas, particularly ATLL. This was confirmed by a positive anti-HTLV-1 serology. Our final diagnosis was acute variant ATLL. Different T-cell lymphomas can involve the skin with overlapping clinical, histomorphologic and immunohistochemical features. Some clinical and pathologic features should alarm dermatologists and pathologists to the possibility of ATLL particularly in patients from HTLV-1 endemic geographic areas.

Status of humoral and cellular immune markers in human T-cell lymphotropic virus type 1 (HTLV-1) asymptomatic carriers in northeastern Iran, Mashhad.

It is estimated that about 10-20 million peoples are infected with human T-cell leukemia virus type 1 (HTLV-1) around the world and suffered from HTLV-related diseases. The present study was aimed to evaluate the cellular immunity, T-cell activation, humoral immunity, and inflammatory response hallmarks which affect HTLV-1-associated disease progression. A total of 78 participants were included in the study, comprising 39 HTLV-1 asymptomatic careers (ACs) and 39 healthy controls. The HTLV-proviral load (PVL) was determined via real-time PCR technique, and anti-HTLV antibody, sIL2R, sCD30, Neoptrin, hs-CRP, IgE, anti-VCA, anti-EBNA, and anti-EA were assessed by ELISA method. Mean PVL in ACs was 352.7 ± 418.7 copies/104 PBMCs. A significant higher level of sIL-2R was observed in ACs (P < 0.0001). Anti-VCA antibody titer in ACs and healthy controls was 80.72 ± 105.95 and 156.05 ± 130.71, respectively (P = 0.007). Intriguingly, suppression in ACs immune response was not observed. Resultantly, HTLV-1 infection has no effect on the humoral immune response in ACs but greater T-cell activation and function cellular responses were detected. Finally, more studies on various immune markers in adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients are greatly needed to illuminate the association of ACs' immune status with the development of the related diseases.