Relevance of HTLV-1 proviral load in asymptomatic and symptomatic patients living in endemic and non-endemic areas of Argentina

Virus-host immune interaction in asymptomatic HTLV-1 carriers

Human T-cell leukemia virus type 1 (HTLV-1) induces chronic long-term latent infection that can cause fatal diseases, including adult T-cell leukemia. HTLV-1 production is poor and undetectable during the asymptomatic phase of infection. Virus-host immune interaction in latent infection has not been fully determined. In the present study, virus-specific antibody and T-cell responses in asymptomatic HTLV-1 carriers (n = 77) were investigated. Neutralizing antibody responses were significantly higher in individuals with higher anti-Env SU (gp46) antibody levels and positively correlated with proviral loads. Overnight ex vivo culture of peripheral blood mononuclear cells resulted in detectable HTLV-1 Gag antigen (p19) expression in CD4+ T cells and interferon-γ (IFN-γ) induction in CD8+ T cells. Frequencies of these p19-expressing CD4+ T cells and non-specific IFN-γ-induced CD8+ T cells were positively correlated with proviral loads, respectively. Tax-specific CD8+ T-cell frequencies were not associated with proviral loads but inversely correlated with the ratios of p19-expressing CD4+ T-cell frequencies to proviral loads, implying the involvement of Tax-specific CD8+ T cells in the control of HTLV-1 replication. These results provide insights into the elucidation of the virus-host immune interaction in latent HTLV-1 infection.

IMPORTANCE

Human T-cell leukemia virus type 1 (HTLV-1) can cause fatal diseases, including adult T-cell leukemia in humans after long-term asymptomatic infection. In asymptomatic HTLV-1 carriers, substantial proviruses are detectable in lymphocytes, and the association of a higher proviral load with a higher risk of disease progression has been observed. However, viral replication is controlled and HTLV-1 production is poor in asymptomatic carriers. Virus-host immune interaction during latent infection has not been fully determined. In the present study, virus-specific antibody and T-cell responses in asymptomatic HTLV-1 carriers were investigated. Neutralizing antibody responses were positively correlated with proviral loads. Tax-specific CD8+ T-cell frequencies were not associated with proviral loads but inversely correlated with the ratios of p19-expressing CD4+ T-cell frequencies to proviral loads, supporting the notion that Tax-specific CD8+ T-cell responses play an important role in the control of HTLV-1 replication. These results provide insights into the mechanism of virus-host immune interaction in latent HTLV-1 infection.

Declining trend of HTLV-1 among organ/ tissue donors in Iranian Tissue Bank between 2014-2021

BACKGROUND

Human T-cell Lymphotropic Virus type-1 (HTLV-1) infection is associated with serious disorders, including Adult T-cell Leukemia/Lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). In addition to sexual, vertical, parenteral, and blood transfusion, organ/tissue transplantation is considered as a transmission route of HTLV infection. Given the substantial risk of HTLV-1 transmission and the subsequent development of HAM/TSP (approximately 40%) in kidney transplant recipients, pre-transplant donor screening is crucial. The present study aimed to investigate the prevalence of HTLV-1 in potential organ/tissue donors referred to the Iranian Tissue Bank and Research Center (ITBRC).

MATERIALS AND METHODS

The study population was potential organ and/or tissue donors referred to ITBRC between 2014 and 2021, including two groups of brain death (potential donors of organs and/or tissues) and circulatory death donors (potential tissue donors from Iranian Legal Medicine Organization). Initial screening was performed using enzyme-linked immunosorbent assay (ELISA), and positive cases were confirmed for HTLV-1 infection with polymerase chain reaction (PCR).

RESULTS

111 out of 3,814 donors were positive for HTLV-1 (3%). The rate of positive tests between 2014 and 2017 was 6%, which was significantly higher than the positive tests percentage between 2017 and 2021 with 0.5% (P-value < 0.001). The rate of test positivity in females was 4% compared to 2% in males (P-value = 0.001). Furthermore, individuals diagnosed with brain death exhibited a significantly lower likelihood of HTLV-1 infection (0.2%) compared to cases with circulatory death (4%) (P-value < 0.001).

CONCLUSION

Considering the contraindication of organ/tissue donation from donors with HTLV-1 positive test, these findings give an insight into the prevalence of HTLV-1 among potential organ/tissue donors in Iran. Moreover, the higher prevalence of HTLV-1 infection in circulatory death donors from Iranian Legal Medicine Organization urges for cautious evaluation in these donors.

TLR7 rs179008 (A/T) and TLR7 rs3853839 (C/G) polymorphisms are associated with variations in IFN-α levels in HTLV-1 infection

Introduction

TLR7 detects the presence of single-stranded RNA (ssRNA) viruses, including human T-lymphotropic virus 1 (HTLV-1), and triggers antiviral and inflammatory responses that are responsible for infection control. Genetic variations in the TLR7 gene may alter cytokine production and influence the course of HTLV-1 infection. In the present study, the associations of TLR7 gene polymorphisms with HTLV-1-related symptoms, receptor expression levels, IFN-α and TNF-α levels and the proviral load were investigated.

Methods

Blood samples from 159 individuals with HTLV-1 infection (66 with inflammatory diseases and 93 asymptomatic individuals) and 159 controls were collected. The genotyping of polymorphisms, TLR7 gene expression analysis and the quantification of the proviral load were performed by real-time PCR, and cytokine measurement was performed by enzyme-linked immunosorbent assay (ELISA).

Results

Carriers of the polymorphic allele for TLR7 rs179008 (A/T) had lower levels of IFN-α, while carriers of the polymorphic allele for TLR7 rs3853839 (C/G) had higher levels of TLR7 and IFN-α expression. The polymorphisms were not associated with symptoms of diseases related to HTLV-1 infection. The combination of A/G alleles for the TLR7 rs179008 (A/T) and TLR7 rs3853839 (C/G) polymorphisms was associated with increased IFN-α levels and a decreased proviral load.

Discussion

Although the polymorphisms did not influence the presence of symptoms of diseases caused by HTLV-1, carriers of the wild-type alleles for TLR7 rs179008 (A/T) and the polymorphism for TLR7 rs3853839 (C/G) appears to have a stronger antiviral response and increased infection control.

HTLV infection in urban population from Mato Grosso do Sul, Central Brazil

BACKGROUND

Brazil has the highest number of HTLV-1 infection in Latin America, with around one million cases spread unevenly across regions. However, there is a limited number of studies on this infection in the general population. This cross-sectional study aimed to estimate the prevalence of HTLV as well as identify types, and subtypes of HTLV among the urban population of Campo Grande, capital of Mato Grosso do Sul state (MS).

RESULTS

Between July 2023 and March 2024, all information was obtained from self-reported interviews, and blood samples were collected and screened for anti-HTLV-1/2 by immunoassay and confirmed using the immunoblot method. The proviral DNA of HTLV-1/2 in positive samples was quantified by real-time PCR (qPCR) and genotyped by nucleotide sequencing (Sanger's method). The study enrolled 611 participants, with the majority being women (90.54%), mixed race (46.32%), heterosexual (87.64%), and with a median age of 39 years. The prevalence rate of anti-HTLV-1 infection was 0.82% (CI 95% 0.34-1.96). All positive samples (n = 5) were identified as belonging to the Cosmopolitan subtype, one belonging to Japanese and four to Transcontinental subgroups. Among the five positive individuals, two presented symptoms associated with HTLV-1 infection.

CONCLUSION

This study highlights an intermediate prevalence of HTLV-1 in the urban population of Campo Grande, Mato Grosso do Sul, and provides epidemiological information that could help bridge the gaps in the distribution of HTLV in the general population. Also, medical care was provided for individuals presenting clinical manifestations who were previously unaware of their serological status.

A Systematical Review on ART Use in HTLV Infection: Clinical, Virological, and Immunological Outcomes

Human T-cell lymphotropic virus (HTLV) infection affects over ten million people worldwide, but there is no effective treatment so far. This review describes the virological, immunological, and clinical outcomes of antiretroviral therapy (ART) in people with HTLV infection. This systematic review followed PRISMA reporting guidelines and was registered in PROSPERO: CRD42022350076. The Newcastle-Ottawa Scale, adapted for cross-sectional studies, and Rob-2 were used to assess the methodological quality of these studies. Systematic searches were conducted in the Medline (PubMed), Scopus (Elsevier), Cochrane Library, and Web of Science (Clarivate Analytics) databases. We retrieved data from eight methodologically diverse articles on treatment of patients infected by HTLV-1 or HTLV-2 alone, or coinfected by HIV-1, who received Raltegravir, Tenofovir, Lamivudine, or Zidovudine. The proviral load decreased in three out of seven studies over 4 to 48 weeks of antiretroviral use. Cellular immune response (CD4, CD8, CD25, CD69, and CD71 cells) was evaluated in six studies. While no significant clinical improvement was observed, all studies reported clinical stability during treatment. Despite the demonstrated antiviral activity of ART, in vitro, clinical improvement was not proven. Most studies showed disease stability during ART use, suggesting potential clinical benefits. There is a need of larger, well-controlled trials to define the role of ART in the treatment of HTLV infection.

Evaluating tocilizumab safety and immunomodulatory effects under ocular HTLV-1 infection in vitro

There is growing interest in evaluating the safety and therapeutic potential of existing treatments such as tocilizumab (TCZ), an IL-6 receptor antagonist used to treat inflammatory diseases. However, there have been reports of increased inflammation in patients with HTLV-1 uveitis after TCZ treatment, and its ocular safety in the HTLV-1 infected state remains unknown. This study focused on assessing the impact of TCZ on HTLV-1-infected ocular cells using an in vitro model in which retinal pigment epithelial cells were cocultured with irradiated HTLV-1-infected T-cell lines. TCZ did not significantly affect cellular viability, inflammatory markers, or HTLV-1 proviral loads at various concentrations (25/50/100 µg/ml), indicating no increased risk of HTLV-1 viral infection and no exacerbation of the inflammatory aspects of HTLV-1 infection in the ocular cells. These promising results support the potential of TCZ as a safe treatment option for HTLV-1-infected patients, particularly those with eye infections.

The Global Epidemiology of Bovine Leukemia Virus: Current Trends and Future Implications

Bovine leukemia virus (BLV) is a retrovirus that causes enzootic bovine leucosis (EBL), which is the most significant neoplastic disease in cattle. Although EBL has been successfully eradicated in most European countries, infections continue to rise in Argentina, Brazil, Canada, Japan, and the United States. BLV imposes a substantial economic burden on the cattle industry, particularly in dairy farming, as it leads to a decline in animal production performance and increases the risk of disease. Moreover, trade restrictions on diseased animals and products between countries and regions further exacerbate the problem. Recent studies have also identified fragments of BLV nucleic acid in human breast cancer tissues, raising concerns for public health. Due to the absence of an effective vaccine, controlling the disease is challenging. Therefore, it is crucial to accurately detect and diagnose BLV at an early stage to control its spread and minimize economic losses. This review provides a comprehensive examination of BLV, encompassing its genomic structure, epidemiology, modes of transmission, clinical symptoms, detection methods, hazards, and control strategies. The aim is to provide strategic information for future BLV research.

Prevalence and characteristics of HTLV-associated uveitis in patients from Bahia, an endemic area for HTLV - 1 in Brazil

BACKGROUND

HTLV-1-associated uveitis (HAU) is an inflammatory reaction of the choroid, retina, optic nerve and vitreous that can lead to vision impairment. The worldwide prevalence of HAU varies widely.

OBJECTIVE

To determine the prevalence of HAU in patients from Salvador, Bahia-Brazil, and describe uveitis type and associated symptoms.

METHODS

Cross-sectional analytical study to determine the prevalence of uveitis in HTLV-1-infected patients recruited in Bahia, Brazil, a region considered endemic for HTLV-1. Patients were enrolled at a local reference center for HTLV (infected) and at an outpatient ophthalmology clinic (noninfected group). All patients were examined by the same ophthalmologist following a single protocol. Prevalence ratios (PR) were calculated.

RESULTS

A total of 168 consecutively examined HTLV-1-infected patients and 410 noninfected patients (randomly selected) were included. Females predominated (82.1%) in the HTLV-1-infected group (versus 64.4% in the uninfected group) (p < 0.001). The mean age of infected and uninfected patients was 53.2 and 62.8 years, respectively (p < 0.001). The prevalence of uveitis in HTLV-1+ and HTLV-1- patients was 7.14% and 0.73%, respectively (PR = 9.76; 95CI%:2.79-34.15; p < 0.01). Bilateral intermediate uveitis, associated with symptoms including visual disturbances and floaters, was most commonly identified in the HTLV-1-infected patients, whereas unilateral anterior uveitis, in association with symptoms such as blurring and ocular pain, was more common in the uninfected group.

CONCLUSION

The prevalence of uveitis in patients with HTLV-1 was markedly higher than in uninfected subjects. HAU patients were mostly asymptomatic and exhibited bilateral presentation, with uveitis more frequently localized in the intermediate chamber.

Integrated molecular and immunological features of human T-lymphotropic virus type 1 infection and disease progression to adult T-cell leukaemia or lymphoma

The human T-lymphotropic virus type 1 (HTLV-1) retrovirus infects 10-20 million people globally, with endemic regions in southwestern Japan, the Caribbean basin, Africa, and central Australia. HTLV-1 is associated with lifelong infection and immune suppression, resulting in a range of serious sequalae, including adult T-cell leukaemia or lymphoma (ATLL) in 5% of cases. To date, there are no preventive or curative treatments for HTLV-1 and treatment outcomes for ATLL remain generally poor. Depending on the disease subtype, overall survival is 8-55 months. Recent advancements in the past decade have identified genetic, molecular, and immunological events occurring throughout the lives of individuals infected with HTLV-1 and of those who progress to ATLL. In addition, updated guidelines for clinical management have been published. With the aim of focusing research efforts on the development of treatments for both HTLV-1 infections and ATLL, we have conceptualised a four-step disease model for HTLV-1-associated ATLL: (1) viral exposure, (2) establishment of chronic infection, (3) cellular transformation and evolution, and (4) disease presentation and management. For each stage we describe the clinical features, molecular and immunological factors involved, potential biomarkers of disease progression, and the therapeutic applicability of individual targets. We also discuss emerging concepts and novel treatment approaches. Our hope is that this model will promote research interest and guide the testing of new treatments for this neglected virus and its associated rare cancer.

Frequency and characteristics of HTLV in migrants: results from the +Redivi collaborative network in Spain

INTRODUCTION

The objective of this study was to describe the main characteristics of migrants diagnosed with human T-lymphotropic virus (HTLV) infection within the +Redivi Spanish network.

METHODS

Patients with a diagnosis of HTLV type 1 or 2 in +Redivi from October 2009 to December 2020 were included. Diagnosis was based on positive HTLV serology (enzyme-linked immunosorbent assay (ELISA)/chemiluminescent immunoassay (CLIA)) with line immunoassay (LIA)/Western blot with/without polymerase chain reaction (PCR).

RESULTS

A total of 107/17 007 cases (0.6%) had a final diagnosis of HTLV infection: 83 (77.67%) HTLV-1 infections, 6 (5.6%) HTLV-2 infections and 18 (16.8%) non-specified. The majority (76, 71%) were female, median age was 42 years and median time from arrival to Spain until consultation was 10 years. The group included 100 (93.5%) immigrants and 7 (6.6%) visiting friends and relatives (VFR)-immigrants. Most patients were from South America (71, 66.4%), followed by Sub-Saharan Africa (15, 14%) and Central America-Caribbean (13, 12.1%). Around 90% of patients were asymptomatic at presentation and diagnosed as part of screening programs. Median duration of follow-up was 5 years (IQR 2-7). Regarding HTLV-associated conditions, 90 patients (84.2%) had none, 7 (6.5%) had tropical spastic paraparesis , 5 (4.7%) had other associated conditions (dermatitis, uveitis, pulmonary disease), 3 (2.8%) had other neurological symptoms and 2 (1.9%) had adult T-cell leukaemia/lymphoma. No patients with HTLV-2 had HTLV-associated conditions. Four patients (3.7%) died. Concomitant diagnoses were found in 41 (38.3%) patients, including strongyloidiasis in 15 (14%) and HIV co-infection in 4 (3.7%). In 70% of patients, screening of potential contacts was not performed/recorded.

CONCLUSIONS

HTLV infections (the majority due to HTLV-1) were mainly diagnosed in asymptomatic migrants from Latin America (generally long-settled immigrants and the majority female with the consequent implications for screening/prevention). A high rate of association with strongyloidiasis was found. In the majority, screening of potential contacts was not performed, representing a missed opportunity for decreasing the under diagnosis of this infection.

Making Visible HTLV Infection in a Non-endemic Area of Argentina

In Argentina, the human T-cell lymphotropic virus type 1 (HTLV-1) infection has been documented mainly among blood banks with a prevalence of ~0.02–0.046% for Buenos Aires city, 0.8% for the northeast, and 1% for the northwest; both areas are considered endemic for HTLV-2 and 1, respectively. Policies and specific guidelines for testing blood donors for HTLV are included since 2005. Screening for antibodies is performed at blood banks and confirmatory testing is performed at reference laboratories. There are no specific recommendations for the assistance of communities and individuals affected, nor referral to specialized clinics on the HTLV infection. In 2016, as a strategy of intervention, we opened a specialized clinical attendance in a referral infectious diseases public hospital for the comprehensive approach to patients with HTLV, offering follow-up and counseling for patients and their families for the early diagnosis of HTLV-1/2 and related diseases. During the study, 124 patients with presumptive HTLV positive diagnosis from blood bank, symptomatic patients (SPs), relatives, and descendants visited the unit. A total of 46 patients were HTLV positive (38 HTLV-1 and 8 HTLV-2). There were nine SPs (2 adult T-cell leukemia/lymphoma [ATL] and 7 HTLV-1-associated myelopathy/tropical spastic paraparesis [HAM/TSP]). All patients with HTLV-1 and−2 were offered to study their relatives. Two out of 37 (5.4%) descendants tested were positive for HTLV-1. Sexual partners were studied; among 6 out of 11 couples (54.5%) were found positive (5 HTLV-1 and 1 HTLV-2). Other relatives, such as mothers (1/2) and siblings (1/6), were positive for HTLV-1. According to the place of birth among HTLV-1 carriers, 58% were born in an endemic area or in countries where HTLV infection is considered endemic while for HTLV-2 carriers, 12.5% were born in an endemic area of Argentina. The proviral load (pVL) was measured in all, patients with HTLV-1 being higher in symptomatic compared with asymptomatic carriers. In addition, two pregnant women were early diagnosed during their puerperium and breastmilk replacement by formula was indicated. Inhibition of lactation was also indicated. Our study provides tools for a multidisciplinary approach to the infection and reinforces the importance of having specialized clinical units in neglected diseases, such as HTLV for counseling, clinical and laboratory follow-up, and providing useful information for patients for self-care and that of their families.

Association of the rs4143815 polymorphism of PDL1 gene with HTLV-1 infection and proviral load in asymptomatic blood donors in northeast Iran

Obviously, genetic differences, including mutations and polymorphisms, can play an important role in viral infections, So in this case-control study, which contained 81 Human T-cell leukemia virus type 1(HTLV-1) asymptomatic carriers (ACs) and 162 healthy controls (HCs), the rs4143815 polymorphism of PDL1 gene investigated. This polymorphism is the site of miR-570 binding and it can influence immune system responses. The rs4143815 polymorphism was evaluated by allele-specific polymerase chain reaction (AS-PCR) and proviral load (PVL) levels by quantitative real-time PCR (q PCR). The results demonstrated that C allele (p=0.027) and CC genotype (p=0.031) of rs4143815 polymorphism was significantly higher in ACs than HCs group also, the PVL in ACs with C allele (p=0.020) was higher significantly. Thus, the rs4143815 polymorphism can play a vital role in HTLV-1 infection. This article is protected by copyright. All rights reserved.

Case Report: Relevance of an Accurate Diagnosis and Monitoring of Infective Dermatitis Associated With Human T-Lymphotropic Virus Type 1 in Childhood

Human T-lymphotropic virus type 1 (HTLV-1) is a neglected retrovirus distributed worldwide and the ethiological agent of several pathologies, such as adult T-cell leukemia/lymphoma (ATLL), a chronic myelopathy known as HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) and infective dermatitis associated with HTLV-1 (IDH). HTLV-1 presents tropism for CD4⁺ T cells and induces deregulation of the cytokine profile. IDH is a severe, chronic superinfected eczema generally associated with Staphylococcus aureus and/or Streptococcus beta haemolyticus infection that responds partially to antibiotic therapy but prompt recurrence develops upon treatment withdrawal. IDH could be a risk factor for progression toward both HAM/TSP and ATLL and, similarly to other diseases associated with HTLV-1, it is sub-diagnosed particularly in non-endemic areas. Here, we present a case of IDH in a young boy living in Buenos Aires with symptoms since 2010, at the age of 5. HTLV-1 infection was suspected and confirmed in 2016. The patient exhibited chronic dermatosis with exudative eruption involving mainly the scalp, retroauricular regions, neck and abdomen. Clinical evaluations, routine laboratory tests, full blood count, and HTLV-1 diagnosis for this case are included.

The association of polymorphisms (rs2227981 and rs10204525) of PDCD1 gene with susceptibility to human T-cell leukemia virus type 1

Human T-cell leukemia virus type 1 (HTLV-1) is the first retrovirus as the causative agent of two serious diseases in human is known. Programmed cell death-1 (PD-1) is a regulatory protein that has an important role in immune system response and created exhaustion phenotype in T cells at chronic infections; therefore, it can impair anti-viral responses. Since the single nucleotide polymorphisms (SNP) in PD-1gene may influence infection with HTLV-1virus, so in this research, association between SNPs in exon 5 of PD-1 gene with susceptibility to HTLV-1 infection and proviral load (PVL) in Iran's population studied. In this case-control study, PD-1 rs2227981 and rs10204525 polymorphisms were evaluated in 81 HTLV-1 asymptomatic carriers (ACs) and 162 healthy individuals (control groups). These polymorphisms were genotyped by Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Moreover, PVL was detected by quantitative real-time PCR (Q-RT-PCR). The results indicated that frequency of GA and AA genotypes in rs10204525 polymorphism was higher in ACs group (82.7%) than control group (26.5%) significantly; and GA + AA genotypes were significantly associated with HTLV-1 infection (OR = 13.244, 95%CI = 6.755-25.968, p = 0.000); but CT + TT genotypes in rs2227981 polymorphism, were as a protective factor against HTLV-1 infection (OR = 0.473, 95%CI = 0.279-0.813, P = 0.009). However, there was no significant difference between these polymorphisms and HTLV-1 PVL.

BoLA-DRB3 Polymorphism is Associated with Differential Susceptibility to Bovine Leukemia Virus-Induced Lymphoma and Proviral Load

Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leucosis. However, less than 5% of BLV-infected cattle will develop lymphoma, suggesting that, in addition to viral infection, host genetic polymorphisms might play a role in disease susceptibility. Bovine leukocyte antigen (BoLA)-DRB3 is a highly polymorphic gene associated with BLV proviral load (PVL) susceptibility. Due to the fact that PVL is positively associated with disease progression, it is believed that controlling PVL can prevent lymphoma development. Thus, many studies have focused on the relationship between PVL and BoLA-DRB3. Despite this, there is little information regarding the relationship between lymphoma and BoLA-DRB3. Furthermore, whether or not PVL-associated BoLA-DRB3 is linked to lymphoma-associated BoLA-DRB3 has not been clarified. Here, we investigated whether or not lymphoma-associated BoLA-DRB3 is correlated with PVL-associated BoLA-DRB3. We demonstrate that two BoLA-DRB3 alleles were specifically associated with lymphoma resistance (*010:01 and *011:01), but no lymphoma-specific susceptibility alleles were found; furthermore, two other alleles, *002:01 and *012:01, were associated with PVL resistance and susceptibility, respectively. In contrast, lymphoma and PVL shared two resistance-associated (DRB3*014:01:01 and *009:02) BoLA-DRB3 alleles. Interestingly, we found that PVL associated alleles, but not lymphoma associated alleles, are related with the anti-BLV gp51 antibody production level in cows. Overall, our study is the first to demonstrate that the BoLA-DRB3 polymorphism confers differential susceptibility to BLV-induced lymphoma and PVL.