Estimation of HTLV-1 vertical transmission cases in Brazil per annum

Multicenter cross-sectional study of HTLV-1 prevalence and associated risk factors in epidemiologically relevant groups across Brazil

Background

Human T cell lymphotropic virus type 1 (HTLV-1) is highly endemic in Brazil, necessitating surveillance studies to understand its epidemiology. While previous research has focused on either specific cities or populations, there is a need for multicenter studies encompassing epidemiologically relevant populations to ascertain more accurate prevalence rates and predictors of HTLV-1 infection in the country.

Methods

We conducted a multicenter, cross-sectional study involving 3,184 participants across seven cities and five study populations in Brazil. Blood samples were collected, and the prevalence of HTLV-1 infection was determined by enzyme-linked immunosorbent assay (ELISA) and Western blot. Binary logistic regression analysis was used to determine risk factors of HTLV-1 infection.

Results

Among the total study population, 1,135 (35.7%) were aged >40 years and 1,704 (53.5%) were female. The overall prevalence of HTLV-1 infection was 0.5% (95% CI: 0.3-0.8), with variation observed among the cities or study populations. Factors associated with HTLV-1 infection included age > 40 years (OR, 8.867; 95% CI: 1.824-43.099), female gender (OR, 4.604; 95% CI: 1.184-17.903), and Hepatitis C virus (HCV) infection (OR, 13.995; 95% CI: 2.374-82.506). The identification of older age and female gender, coupled with the high prevalence of HTLV-1 in HIV-positive patients, suggests sexual transmission as the primary route of HTLV-1 infection.

Conclusion

Our study reveals varied prevalence rates of HTLV-1 infection across diverse populations and cities in Brazil. The association of older age, female gender, and HCV, emphasizes the need for tailored interventions to prevent HTLV-1 transmission.

Trends of changes in human T-cell leukemia virus type 1 epidemiology in Japan and globally

Human T-cell leukemia virus type 1 (HTLV-1) has been identified as a cause of adult T-cell leukemia-lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Despite several HTLV-1 endemic areas being identified, comprehensive investigations have yet to be conducted in all the regions of the world. This review aims to summarize the current reports on HTLV-1. As vertical transmission is known to be a risk factor for ATL development, prevention strategies have been initiated in Japan, and these efforts may be related to the decrease in the estimated number of HTLV-1 carriers in Japan. In numerous HTLV-1 endemic regions, the prevalence of HTLV-1 increases with age, which may be attributed to horizontal infection. However, the incidence of HTLV-1 infection appears to be high among adolescents and young adults in Japan, especially in non-endemic areas. The clinical significance of HTLV-1 infections, other than ATL and HAM/TSP, has recently been documented. Consequently, it is imperative to develop treatment strategies for HTLV-1 infections, including measures to prevent horizontal infections.

Intrafamilial Transmission of HTLV-1 and HTLV-2 in Indigenous Peoples of the Brazilian Amazon: Molecular Characterization and Phylogenetic Analysis

Human T-limphotropic virus 1 infection has a global distribution, with a high prevalence in some regions of Brazil and the world, while HTLV-2 infection is endemic mainly among indigenous people and drug users. To analyze intrafamilial transmission of HTLV-1/2 in five Kayapó indigenous peoples (Gorotire, Kararaô, Kokraimoro, Kubenkokre, and Xikrin do Bacajá), we investigated 1452 individuals who underwent serological and molecular tests. Among the 276 indigenous people with positive results, we identified intrafamily transmission in 42.7% of cases, representing 38 families. It was possible to suggest horizontal and vertical transmissions in 15.8% (6/38) and 47.4% (18/38) of the family groups, respectively. In 15.8%, it was not possible to suggest the route, which indicated that the transmission may have occurred through both vertical and horizontal routes. Through phylogenetic analyses, 35 samples positive for HTLV-2 were sequenced and classified as subtype 2c, and the two samples that tested positive for HTLV-1 were shown to belong to the cosmopolitan subtype, transcontinental subgroup (HTLV-1aA). This study confirms the intrafamilial transmission of HTLV-1/2 infection in indigenous people of the Brazilian Amazon, highlighting the importance of the sexual and mother-to-child transmission routes in maintaining the virus in these people.

Clinical Features and Survival Outcome in Aggressive-Type Adult T-Cell Leukemia/Lymphoma Patients: Real-Life Experience of a Single Center from an HTLV-1 Endemic Country

Background and Objectives: Adult T-cell leukemia/lymphoma (ATLL) is a highly aggressive T-cell lymphoproliferative disease associated with the human T-cell lymphotropic virus type I (HTLV-1). ATLL is a rare disease, found more frequently in HTLV-1-endemic areas, Romania being one of them. Despite treatment advances, the prognosis remains dismal. We aimed to describe the clinical, biological, and survival outcome features of Romanian patients with aggressive-type ATLL. Materials and Methods: We report the data of a prospective, observational, and unicentric study of all 20 patients diagnosed with lymphoma and acute types of ATLL at our center over the past 12 years. Data were collected from the patients' medical records. Results: Lymphoma-type ATLL (60%) was more common than acute-type ATLL (40%). Median age at diagnosis was 40.5 years, and most patients were female. Laboratory data revealed significant differences between acute and lymphoma-type ATLL, namely, higher leukocyte (p = 0.02) and lymphocyte counts (p = 0.02) and higher levels of corrected calcium (p = 0.001) in acute-type ATLL. All patients received chemotherapy, and only two underwent allogeneic stem cell transplantation. Only six patients obtained a complete or partial response to chemotherapy, mostly the lymphoma-type ones. The median survival for all patients was 6.37 months, with higher survival in the lymphoma-type ATLL (8.16 months) than in the acute-type (3.60 months). Normal calcium levels (p = 0.011), uric acid (p = 0.005), BUN score (p = 0.000), JCOG-PI moderate risk (p = 0.038), and obtaining complete or partial response (p = 0.037) were associated with higher survival. Conclusion: Aggressive-type ATLL among Romanian patients presents distinct characteristics, including younger age at diagnosis, female predominance, and higher incidence of lymphoma-type ATLL compared to currently reported data. Survival remains very low, with all subtypes experiencing a median survival of less than one year.

Could Cesarean Delivery Help Prevent Mother-to-Child Transmission of Human T-Lymphotropic Virus Type 1?

BACKGROUND

Mother-to-child transmission (MTCT) of human T-lymphotropic virus type 1 (HTLV-1) is an important route of transmission that can cause lifelong infection. There is high morbidity and mortality due to adult T-cell leukemia/lymphoma, HTLV-1-associated myelopathy (HAM), and other inflammatory disorders. These conditions develop in nearly 10% of people with HTLV-1 infection, with a higher risk if infection occurs early in life. Identification of risk factors can inform targeted measures to reduce HTLV-1 MTCT. This study aimed to investigate the potential of cesarean delivery to prevent HTLV-1 MTCT.

METHODS

We performed a review of the cases of women and their offspring under regular follow-up at the HTLV-1 outpatient clinic at the Institute of Infectious Diseases Emilio Ribas.

RESULTS

A total of 177 HTLV-1-infected women and 369 adult offspring were investigated. Overall, 15% of the children were positive for HTLV-1 and 85% were negative. Regarding vertical transmission, we found that a breastfeeding duration of >6 months was associated with MTCT. Moreover, maternal proviral load was not associated with transmission, but high educational level and cesarean delivery were identified as protective factors.

CONCLUSIONS

HTLV-1 MTCT was associated with mother's age at delivery of >25 years, low educational level, prolonged breastfeeding, and vaginal delivery.

Human T-cell lymphotropic virus type 1 (HTLV-1) proposed vaccines: a systematic review of preclinical and clinical studies

BACKGROUND

Numerous vaccination research experiments have been conducted on non-primate hosts to prevent or control HTLV-1 infection. Therefore, reviewing recent advancements for status assessment and strategic planning of future preventative actions to reduce HTLV-1 infection and its consequences would be essential.

METHODS

MEDLINE, Scopus, Web of Science, and Clinicaltrials.gov were searched from each database's inception through March 27, 2022. All original articles focusing on developing an HTLV-1 vaccine candidate were included.

RESULTS

A total of 47 studies were included. They used a variety of approaches to develop the HTLV-1 vaccine, including DNA-based, dendritic-cell-based, peptide/protein-based, and recombinant vaccinia virus approaches. The majority of the research that was included utilized Tax, Glycoprotein (GP), GAG, POL, REX, and HBZ as their main peptides in order to develop the vaccine. The immunization used in dendritic cell-based investigations, which were more recently published, was accomplished by an activated CD-8 T-cell response. Although there hasn't been much attention lately on this form of the vaccine, the initial attempts to develop an HTLV-1 immunization depended on recombinant vaccinia virus, and the majority of results seem positive and effective for this type of vaccine. Few studies were conducted on humans. Most of the studies were experimental studies using animal models. Adenovirus, Cytomegalovirus (CMV), vaccinia, baculovirus, hepatitis B, measles, and pox were the most commonly used vectors.

CONCLUSIONS

This systematic review reported recent progression in the development of HTLV-1 vaccines to identify candidates with the most promising preventive and therapeutic effects.

Economic analysis of antenatal screening for human T-cell lymphotropic virus type 1 in Brazil: an open access cost-utility model

BACKGROUND

Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that causes severe diseases, such as aggressive cancer or progressive neurological disease. HTLV-1 affects mainly people in areas with low human development index and can be transmitted from mother to child, primarily through breastfeeding. Refraining from breastfeeding is an effective intervention to reduce the risk of infection in infants. However, HTLV-1 antenatal screening is not offered globally. According to WHO, the scarcity of cost-effectiveness studies is considered one of the major barriers to the implementation of policies to prevent HTLV-1 infection. Therefore, this study aimed to assess the cost-effectiveness of antenatal screening and postnatal interventions to prevent HTLV-1 mother-to-child transmission in Brazil and to develop an open-access, editable, mathematical model that can be used by other countries and regions to assess different scenarios.

METHODS

In this cost-utility analysis, we constructed a decision tree and a Markov model to assess the cost-effectiveness of HTLV-1 antenatal screening and postnatal interventions (ie, avoidance of breastfeeding, by suppression of lactation with cabergoline, and provision of formula feed) to reduce transmission. For our model, we used data from Brazil and we took the perspective of the public health-care system to estimate costs.

FINDINGS

The implementation of both screening and interventions would result in the prevention of 1039 infections in infants every year in Brazil with an incremental cost-effectiveness ratio (ICER) of US$11 415 per quality-adjusted life-year (QALY). 88% of all probabilistic sensitivity analysis simulations had ICER values lower than the Brazilian cost-effectiveness threshold ($18 107·74 per QALY). HTLV-1 prevalence in pregnant women, the risk of HTLV-1 transmission when breastfeeding lasts for 6 months or more, and the cost of screening tests were the variables with the largest effect on ICER.

INTERPRETATION

HTLV-1 antenatal screening is cost-effective in Brazil. An open-access model was developed, and this tool could be used to assess the cost-effectiveness of such policy globally, favouring the implementation of interventions to prevent HTLV-1 mother-to-child transmission worldwide.

FUNDING

None.

TRANSLATIONS

For the Portuguese and Spanish translations of the abstract see Supplementary Materials section.

How Can We Prevent Mother-to-Child Transmission of HTLV-1?

The perception of human T-cell leukemia virus type 1 (HTlV-1) infection as a "silent disease" has recently given way to concern that its presence may be having a variety of effects. HTLV-1 is known to cause adult T-cell leukemia (ATL), an aggressive cancer of peripheral CD4 T cells; however, it is also responsible for HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Most patients develop ATL as a result of HTLV-1 mother-to-child transmission. The primary route of mother-to-child transmission is through the mother's milk. In the absence of effective drug therapy, total artificial nutrition such as exclusive formula feeding is a reliable means of preventing mother-to-child transmission after birth, except for a small percentage of prenatal infections. A recent study found that the rate of mother-to-child transmission with short-term breastfeeding (within 90 days) did not exceed that of total artificial nutrition. Because these preventive measures are in exchange for the benefits of breastfeeding, clinical applications of antiretroviral drugs and immunotherapy with vaccines and neutralizing antibodies are urgently needed.

Development of a Novel HTLV-1 Protease: Human Fcγ1 Recombinant Fusion Molecule in the CHO Eukaryotic Expression System

Human T-cell leukaemia virus type 1 (HTLV-1) is the causative agent of two life-threatening diseases, adult T cell leukaemia/lymphoma (ATLL), and HTLV-1-associated myelopathy/tropical spastic (HAM/TSP). HTLV-1 protease (HTLV-1-PR) is an aspartic protease that represents a promising target for therapeutic purposes like human immunodeficiency virus-PR inhibitors (HIV-PR). Therefore, in this study, the human Fc fusion recombinant-PR (HTLV-1-PR:hFcγ1) was designed and expressed for two applications, finding a blocking substrate as a potential therapeutic or a potential subunit peptide vaccine. The PCR amplified DNA sequences encoding the HTLV-1-PR from the MT2-cell line using specific primers with restriction enzyme sites of Not1 and Xba1. The construct was then cloned to pTZ57R/T TA plasmid and, after confirming the PR sequence, subcloned into the pDR2ΔEF1α Fc-expression vector to create pDR2ΔEF1α.HTLV-1-PR:hFcγ1. The integrity of recombinant DNA was confirmed by sequencing to ensure that the engineered construct was in the frame. The recombinant fusion protein was then produced in the Chinese hamster ovary cell (CHO) system and was purified from its supernatant using HiTrap-rPA column affinity chromatography. Then, the immunofluorescence assay (IFA) co-localisation method showed that HTLV-1-PR:hFc recombinant fusion protein has appropriate folding as it binds to the anti-Fcγ antibody; the Fcγ1 tag participates to have HTLV-1-PR:hFcγ1 as a dimeric secretory protein. The development and production of HTLV-1-PR can be used to find a blocking substrate as a potential therapeutic molecule and apply it in an animal model to assess its immunogenicity and potential protection against HTLV-1 infection.

A Review of the Prevention of Mother-to-Child Transmission of Human T-Cell Lymphotrophic Virus Type 1 (HTLV-1) With a Proposed Management Algorithm

Human T cell lymphotropic virus type 1 (HTLV-1) is a human retrovirus that is endemic in a number of regions across the world. There are an estimated 5–10 million people infected worldwide. Japan is currently the only country with a national antenatal screening programme in place. HTLV-1 is primarily transmitted sexually in adulthood, however it can be transmitted from mother-to-child perinatally. This can occur transplacentally, during the birth process or via breastmilk. If HTLV-1 is transmitted perinatally then the lifetime risk of adult T cell leukemia/lymphoma rises from 5 to 20%, therefore prevention of mother-to-child transmission of HTLV-1 is a public health priority. There are reliable immunological and molecular tests available for HTLV-1 diagnosis during pregnancy and screening should be considered on a country by country basis. Further research on best management is needed particularly for pregnancies in women with high HTLV-1 viral load. A first step would be to establish an international registry of cases and to monitor outcomes for neonates and mothers. We have summarized key risk factors for mother-to-child transmission of HTLV-1 and subsequently propose a pragmatic guideline for management of mothers and infants in pregnancy and the perinatal period to reduce the risk of transmission. This is clinically relevant in order to reduce mother-to-child transmission of HTLV-1 and it's complications.

Multi-Epitope Protein as a Tool of Serological Diagnostic Development for HTLV-1 and HTLV-2 Infections

A multi-epitope protein expressed in a prokaryotic system, including epitopes of Env, Gag, and Tax proteins of both HTLV-1 and HTLV-2 was characterized for HTLV-1/2 serological screening. This tool can contribute to support the implementation of public policies to reduce HTLV-1/2 transmission in Brazil, the country with the highest absolute numbers of HTLV-1/2 infected individuals. The chimeric protein was tested in EIA using serum/plasma of HTLV-infected individuals and non-infected ones from four Brazilian states, including the North and Northeast regions (that present high prevalence of HTLV-1/2) and Southeast region (that presents intermediate prevalence rates) depicting different epidemiological context of HTLV-1/2 infection in our country. We enrolled samples from Pará (n = 114), Maranhão (n = 153), Minas Gerais (n = 225) and São Paulo (n = 59) states; they are from blood donors' candidates (Pará and Minas Gerais), pregnant women (Maranhão) and HIV+/high risk for sexually transmitted infection (STI; São Paulo). Among the HTLV-1/2 positive sera, there were co-infections with viral (HTLV-1 + HTLV-2, HIV, HCV, and HBV), bacterial (Treponema pallidum) and parasitic (Trypanosoma cruzi, Schistosma mansoni, Strongyloides stercoralis, Entamoeba coli, E. histolytica, and Endolimax nana) pathogens related to HTLV-1/2 co-morbidities that can contribute to inconclusive diagnostic results. Sera positive for HIV were included among the HTLV-1/2 negative samples. Considering both HTLV-1 and HTLV-2-infected samples from all states and different groups (blood donor candidates, pregnant women, and individuals with high risk for STI), mono or co-infected and HTLV-/HIV+, the test specificity ranged from 90.09 to 95.19% and the sensitivity from 82.41 to 92.36% with high accuracy (ROC AUC = 0.9552). This multi-epitope protein showed great potential to be used in serological screening of HTLV-1 and HTLV-2 in different platforms, even taking into account the great regional variation and different profile of HTLV-1 and HTLV-2 mono or co-infected individuals.

Spread of Human T-Lymphotropic Virus 1 and 2 Among Relatives of People Who Use Illicit Drugs in Northern Brazil

The human T-lymphotropic virus 1 (HTLV-1) and 2 (HTLV-2) can be transmitted between humans by mechanisms associated with horizontal and vertical routes. Recently, high prevalence rates and levels of genetic diversity for HTLV-1 and HTLV-2 were detected among people who use illicit drugs (PWUDs) in the Brazilian state of Pará. None of the PWUDs with HTLV-1 or HTLV-2 were aware of their carrier condition of the retrovirus, and they ability to spread it to their family group, sexual partners, and other contacts. Thus, this study evaluated the presence of HTLV-1 and HTLV-2 in families of PWUDs in the state of Pará, in Northern Brazil. This descriptive study used convenience sampling and accessed 37 PWUDs and their respective families (n = 97) in 18 municipalities in the state of Pará, northern Brazil. All participants provided personal data and were tested for the presence of HTLV-1 and HTLV-2 using enzyme-linked immunosorbent assay and western blotting. HTLV positive samples were selected for Nested-PCR, and viral genotyping by nucleotide sequencing and phylogenetic analysis. HTLV-1 or HTLV-2 infections were detected in 15 families of PWUDs: 27 family members of PWUDs were infected with HTLV-1 (27.8%) and another 20 of them with HTLV-2 (20.6%). Subtypes 1a [subgroup A (54.5%)], 2b (20.5%), and 2c (25.0%) were detected. High horizontal (76.9%) and vertical (61.4%) transmission rates of HTLV were ascertained. Factors that facilitate the acquisition and transmission of HTLV-1 and HTLV-2 were reported by the participants, such as long-term relationships, unprotected sex, breastfeeding, and lack of knowledge about the condition of being a carrier of the retrovirus. Evidence indicates intrafamilial transmission of HTLV from PWUDs to members of their respective families. Key interventions should urgently be employed for the control and prevention of HTLV-1 and HTLV-2 to reduce the spread of this retrovirus in PWUDs and the general population in Northern Brazil and elsewhere.

A Qualitative Study Exploring Perceptions to the Human T Cell Leukaemia Virus Type 1 in Central Australia: Barriers to Preventing Transmission in a Remote Aboriginal Population

Background

Central Australia has the highest recorded prevalence of infection with the human T cell leukaemia virus type 1 (HTLV-1) worldwide. Each of the clinical diseases associated with HTLV-1 have been reported in this region, including deaths due to adult T cell leukaemia, which is causally linked to HTLV-1. Nevertheless, no public health response has been implemented to reduce HTLV-1 transmission among the affected Aboriginal population. In the first study to explore the perceptions of healthcare professionals along with those of Aboriginal people whose communities are actually impacted by HTLV-1, we sought to understand the barriers to preventing HTLV-1 transmission in this remote area.

Methodology/Principal Findings

Semi and un-structured interviews were conducted with 30 Australian Aboriginal people, 26 non-Aboriginal healthcare professionals and 3 non-Aboriginal community workers. The purpose of the interviews was to explore perceptions towards HTLV-1 in a health context with a focus on sexual and reproductive rights. Deductive and inductive analyses were applied to the data and a decolonizing lens brought peripheral stories to the fore. A major finding was the contrast between views expressed by Aboriginal participants and healthcare professionals regarding the provision of knowledge to those affected. Aboriginal participants consistently articulated that they and their communities should be informed of, and can hold, knowledges pertaining to HTLV-1. This finding controverted the perceptions of healthcare professionals that the complexities of the virus would not be well-understood by their Aboriginal patients and that sharing HTLV-1 knowledges might overwhelm Aboriginal people. Further analyses revealed a spectrum of understanding and clinical practice, while also delineating signs of an imagined public health response.

Conclusions/Significance

HTLV-1 remains a neglected infection in Australia. Knowledge of HTLV-1 is held by a privileged medical elite and does not flow to marginalised Aboriginal people living in affected communities. We demonstrate that differences in the perspectives of stakeholders presents a significant barrier to the development of cohesive, culturally safe prevention programs that foster a shared knowledge of HTLV-1. The interview data suggests that a successful public health program is likely to require a dual approach that includes clinical care and community-driven health promotion. Aspects of this approach, which would raise awareness and potentially reduce transmission and lower HTLV-1 prevalence in Central Australia, may be applicable to other endemic settings with similar conditions of social disadvantage, geographic remoteness, resource limitations and cross-cultural challenges.

Clinical and Public Health Implications of Human T-Lymphotropic Virus Type 1 Infection

Human T-lymphotropic virus type 1 (HTLV-1) is estimated to affect 5 to 10 million people globally and can cause severe and potentially fatal disease, including adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The burden of HTLV-1 infection appears to be geographically concentrated, with high prevalence in discrete regions and populations. While most high-income countries have introduced HTLV-1 screening of blood donations, few other public health measures have been implemented to prevent infection or its consequences. Recent advocacy from concerned researchers, clinicians, and community members has emphasized the potential for improved prevention and management of HTLV-1 infection. Despite all that has been learned in the 4 decades following the discovery of HTLV-1, gaps in knowledge across clinical and public health aspects persist, impeding optimal control and prevention, as well as the development of policies and guidelines. Awareness of HTLV-1 among health care providers, communities, and affected individuals remains limited, even in countries of endemicity. This review provides a comprehensive overview on HTLV-1 epidemiology and on clinical and public health and highlights key areas for further research and collaboration to advance the health of people with and at risk of HTLV-1 infection.

Oral health and quality of life of people living with human T-cell leukemia virus-1 in Salvador, Brazil: a cross-sectional study

OBJECTIVE

To compare the oral health status and oral health-related quality of life (OHRQoL) in symptomatic and asymptomatic patients with human T-cell leukemia virus-1 (HTLV-1).

MATERIAL AND METHODS

This cross-sectional study included 204 seropositive patients, classified into two groups, symptomatic and asymptomatic. The first group included patients with neurological symptoms associated with HTLV-1 (n = 69), and the second group, asymptomatic HTLV-1 carriers (n = 135). We evaluated the total unstimulated saliva flow, oral mucosa, the Decayed, Missing, Filled Teeth (DMFT) index, and Periodontal Screening and Recording (PSR). The Oral Health Impact Profile (OHIP14) measured the oral health-related quality of life. General health-related quality of life was measured by the 36-Item Short-Form Health Survey (SF-36). Variables with a value of p < 0.25 in bivariate analysis were selected, together with SF-36 summaries' scores and total OHIP-14, for composing a logistic regression model that had symptomatology as the dependent variable.

RESULTS

The OHIP-14 total score was poor in symptomatic and asymptomatic groups, but with no marked difference between them. Symptomatic patients showed significantly lower SF-36 scores (P ≤ 0.05) compared to asymptomatic ones, except for mental component summary (MCS). Family income (1-2.99 minimal wages), reduced salivary flow, flossing, and lower physical component summary (PCS) were associated (P ≤ 0.05) with symptomatology.

CONCLUSIONS

Symptomatic individuals living with HTLV-1 showed lower HRQoL and poorer OHRQoL compared to asymptomatic ones. Family income, flossing, reduced salivary flow, and lower PCS were associated with symptomatic HTLV-1 individuals.

CLINICAL RELEVANCE

In the present study, symptomatic individuals with HTLV-1 showed higher family income, poorer oral health status, lower salivary flow, poorer OHRQoL, and lower HRQoL compared to asymptomatic ones.

Blocking HTLV-1/2 silent transmission in Brazil: Current public health policies and proposal for additional strategies

Human T-cell lymphotropic viruses 1 and 2 (HTLV-1/2) are relatively common in Brazil but remain silent and neglected infections. HTLV-1 is associated with a range of diseases with high morbidity and mortality. There is no curative treatment for this lifelong infection, so measures to prevent transmission are essential. This narrative review discusses HTLV-1/2 transmission routes and measures to prevent its continuous dissemination. The public health policies that are currently implemented in Brazil to avoid HTLV-1/2 transmission are addressed, and further strategies are proposed.

Mother-to-Child Transmission of Human T-Cell Leukemia Virus Type 1: Mechanisms and Nutritional Strategies for Prevention

Approximately 95% of mother-to-child transmission (MTCT) of human T-cell leukemia virus type-1 (HTLV-1) is derived from prolonged breastfeeding, which is a major cause of adult T-cell leukemia (ATL). Exclusive formula feeding (ExFF) is therefore generally used to prevent MTCT. A recent cohort study revealed that 55% of pregnant carriers chose short-term breastfeeding for ≤3 months in Japan. Our meta-analysis showed that there was no significant increase in the risk of MTCT when breastfeeding was carried out for ≤3 months compared with ExFF (pooled relative risk (RR), 0.72; 95% confidence interval (CI), 0.30-1.77), but there was an almost threefold increase in risk when breastfeeding was carried out for up to 6 months (pooled RR, 2.91; 95% CI, 1.69-5.03). Thus, short-term breastfeeding for ≤3 months may be useful in preventing MTCT. Breastmilk is the best nutritional source for infants, and any approach to minimizing MTCT by avoiding or limiting breastfeeding must be balanced against the impact on the child's health and mother-child bonding. To minimize the need for nutritional interventions, it is necessary to identify factors that predispose children born to carrier mothers to MTCT and thereby predict MTCT development with a high degree of accuracy.

Novel Genetic Constructs for Production of Recombinant HTLV-1/2 Antigens and Evaluation of Their Reactivity to Plasma Samples from HTLV-1-Infected Patients

Human T-cell leukemia virus type 1 (HTLV-1) can cause life-threatening diseases for which there are no effective treatments. Prevention of HTLV-1 infection requires massive testing of pregnant women, blood for transfusion, and organs for transplantation, as well as safe sex. In this context, serological assays are widely used for monitoring HTLV-1 infections. Despite the necessity for recombinant antigens to compose serological tests, there is little information available on procedures to produce recombinant HTLV-1/2 antigens for serological diagnostic purposes. In this work, we tested a series of genetic constructions to select those more amenable for production in bacterial systems. To overcome the constraints in expressing sections of viral envelope proteins in bacteria, we have used the p24 segment of the gag protein as a scaffold to display the immunogenic regions of gp46 and gp21. Nine recombinant antigenic proteins derived from HTLV-1 and five derived from HTLV-2 were successfully purified. The HTLV-1 antigens showed high efficiency in discriminating HTLV-positive samples from HTLV-negative samples using enzyme-linked immunosorbent assays. Interestingly, HTLV-1-positive samples showed a high level of cross-reaction with HTLV-2 antigens. This finding is explained by the high sequence conservation between the structural proteins of these two highly related viruses. In summary, the results presented in this work provide a detailed description of the methods used to produce recombinant HTLV-1 and HTLV-2 antigens, and they demonstrate that the HTLV-1 antigens show strong potential for serological diagnosis of HTLV-1 infections.

Specificity of HTLV screening tests and its impact on health care program costs: The perspective of antenatal screening in Brazil

INTRODUCTION:

Brazil ranks first in the number of HTLV-1/-2-infected individuals worldwide. The high morbidity and mortality of HTLV-1-associated diseases, especially following infection in infancy, requires strong action to reduce vertical transmission.

METHODS:

To facilitate the appraisal of the implementation of the HTLV antenatal screening program by the Brazilian Ministry of Health, we determined the costs in distinct scenarios according to HTLV seroprevalence, specificity of the screening test, and type of confirmatory test.

RESULTS:

HTLV antenatal screening would cost R$ 55,777,012-R$ 77,082,123/year. Screening assays with high specificity reduce the need and cost of confirmatory assays by up to 25%.

CONCLUSIONS:

Careful selection of the screening assay is required to optimize the program.

HTLV-1 targets human placental trophoblasts in seropositive pregnant women

Human T cell leukemia virus type 1 (HTLV-1) is mainly transmitted vertically through breast milk. The rate of mother-to-child transmission (MTCT) through formula feeding, although significantly lower than through breastfeeding, is approximately 2.4%-3.6%, suggesting the possibility of alternative transmission routes. MTCT of HTLV-1 might occur through the uterus, birth canal, or placental tissues; the latter is known as transplacental transmission. Here, we found that HTLV-1 proviral DNA was present in the placental villous tissues of the fetuses of nearly half of pregnant carriers and in a small number of cord blood samples. An RNA ISH assay showed that HTLV-1-expressing cells were present in nearly all subjects with HTLV-1-positive placental villous tissues, and their frequency was significantly higher in subjects with HTLV-1-positive cord blood samples. Furthermore, placental villous trophoblasts expressed HTLV-1 receptors and showed increased susceptibility to HTLV-1 infection. In addition, HTLV-1-infected trophoblasts expressed high levels of viral antigens and promoted the de novo infection of target T cells in a humanized mouse model. In summary, during pregnancy of HTLV-1 carriers, HTLV-1 was highly expressed in placental villous tissues, and villous trophoblasts showed high HTLV-1 sensitivity, suggesting that MTCT of HTLV-1 occurs through the placenta.

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.

What is the prevalence of HTLV-1 among the largest world population of Japanese immigrants and their descendants outside Japan? There are approximately 1.5 million people of Japanese descent in Brazil and most of them living in São Paulo state, Southeast Brazil. The prevalence of HTLV-1 infection was 5.1% among 2,139 individuals from five Japanese associations in São Paulo. The prevalence of 5.1% (95% CI: 4.2–6.0) of HTLV-1 infection found in this study is higher than those observed in other studies conducted in HTLV-1 endemic areas and in specific groups at high risk from Brazil. Among HTLV-infected individuals, the majority (86.2%) were unaware of their HTLV diagnosis. The HTLV-1 infection was associated with the age ≥ 45 years, being the first and second generation of Japanese immigrants, and having sexual partners with a history of blood transfusion. Epidemiological data, along with molecular results also demonstrated high occurrence of similar sequences transmitted intra- and interfamily. The high prevalence of HTLV-1 infection found in this studied population presents an urgent call for preventive and control responses of this infection in Brazil.

Implementation of nationwide screening of pregnant women for HTLV-1 infection in Japan: analysis of a repeated cross-sectional study

Background

Screening of pregnant women carrying human T-lymphotropic virus type 1 (HTLV-1) has a crucial role in reducing the number of HTLV-1 carriers. A national HTLV-1 screening program for pregnant women was started in 2011 in Japan. The purpose of this study is to report on the implementation of this nationwide screening program.

Methods

This was a retrospective repeated cross-sectional study. We used datasets from surveys of HTLV-1-antibody-positive pregnant women performed by the Japan Association of Obstetricians and Gynecologists in 2011, 2013, and 2016. Outcomes for evaluation included the number of persons (pregnant women) who conducted the screening test, the number of positive persons (women) identified by these tests, and the proportion of positive persons to the number of persons (women) who conducted the tests.

Results

Numbers of target facilities changed yearly: 1857 in 2011, 2544 in 2013, and 2376 in 2016. The mean number of screening-test participants increased per facility, but the median increased or decreased. The mean number of positive individuals identified decreased. Multivariate analysis results revealed the number of screenings was slightly reduced yearly, although areas (Kanto and Kinki) and high volume in facility types increased. Regarding the positive rates, some areas (Hokkaido/Tohoku, Kanto, and Chugoku/Shikoku) exhibited decreases or increases by facility type. The number of western blotting (WB) implementations decreased in 2016, positive rates identified by WB decreased in 2016 in all areas, and the number of facility types increased. The number of PCR participants increased in 2016 in Kanto and Kinki, but a decrease in facility type was observed. Positive rates were decreased in all areas (except the central region) but facility types were increased.

Conclusions

The nationwide screening program for HTLV-1 in Japan was almost fully implemented. However, regional variations in screening tests were observed during this implementation. Thus, some incentives are needed to encourage proper implementation across all regions.

Pooling of sera for human T-cell lymphotropic virus (HTLV) screening in a time of increasing health care expenditure and limited resources

Identifying the true prevalence of human T-cell lymphotropic virus, mostly type 1 (HTLV-1), and the number of patients with HTLV-1-associated diseases, in addition to introducing HTLV-1/2 serology during the prenatal of pregnant women and in individuals infected with other viruses that share transmission routes with HTLV-1, are actions that could help to recognize the importance of this virus by WHO and national health organizations, and to control its transmission/dissemination. As Brazil is endemic to HTLV and there is an increase in health care expenditure, but resources are limited, any strategy that could reduce the cost of HTLV screening is needed and welcomed. This study aimed to determine whether the strategy of pooling sera for HTLV antibody determination is feasible and reduces the costs. Two enzyme immunoassays (EIA Murex HTLV-I+II, Diasorin, UK, and Gold ELISA HTLV-1+2, REM Ind. Com. Ltda., SP, Brazil), and serum samples that resulted in different levels of HTLV-1/2 antibodies by EIA and of which a volume allowed assay validation were employed for analysis. The diagnostic sensitivity and specificity and Cohen's Kappa value, as well as the accuracy and precision were analyzed. After validating the five-sample pool using the EIA Murex (Cohen's Kappa = 1.0), the technique was employed for individual cost comparison in 2,625 serum samples from populations at risk of HTLV infections (HBV, HCV, and HIV-infected individuals). The results from individual and pooled samples confirmed the diagnostic sensitivity (100%) and specificity (100%) of the pooling and a cost minimization varying from 60.7% to 73.6%. In conclusion, the results of this study suggest the use of pooling sera in sero-epidemiological surveillance studies and possibly in prenatal care screening programs in Brazil.

A Nationwide Antenatal Human T-Cell Leukemia Virus Type-1 Antibody Screening in Japan

Japan has been running a nationwide antenatal human T-cell leukemia virus type-1 (HTLV-1) antibody screening program since 2010 for the prevention of HTLV-1 mother-to-child transmission. As part of the program, pregnant women are invited to take an HTLV-1 antibody screening test, usually within the first 30 weeks of gestation, during regular pregnancy checkups. Pregnant women tested positive on the antibody screening test undergo a confirmatory test, either western blotting or line immunoassay. In indeterminate case, polymerase chain reaction (PCR) is used as a final test to diagnose infection. Pregnant women tested positive on a confirmatory or PCR test are identified as HTLV-1 carriers. As breastfeeding is a predominant route of postnatal HTLV-1 mother-to-child transmission, exclusive formula feeding is widely used as a postnatal preventive measure. Although there is insufficient evidence that short-term breastfeeding during ≤3 months does not increase the risk of mother-to-child transmission compared to exclusive formula feeding, this feeding method is considered if the mother is eager to breastfeed her child. However, it is important that mothers and family members fully understand that there is an increase in the risk of mother-to-child transmission when breastfeeding would be prolonged. As there are only a few clinical studies on the protective effect of frozen-thawed breastmilk feeding on mother-to-child transmission of HTLV-1, there is little evidence to recommend this feeding method. Further study on the protective effects of these feeding methods are needed. It is assumed that the risk of anxiety or depression may increase in the mothers who selected exclusive formula feeding or short-term breastfeeding. Thus, an adequate support and counseling for these mothers should be provided. In addition to raising public awareness of HTLV-1 infection, epidemiological data from the nationwide program needs to be collected and analyzed. In most cases, infected children are asymptomatic, and it is necessary to clarify how these children should be followed medically.

Emerging sexually transmitted viral infections: Review of human T-lymphotropic virus-1 disease

Human T-lymphotropic virus-1 is a preventable sexually transmitted infection. In the majority of people it is asymptomatic, remaining undiagnosed and thereby contributing to its silent transmission. When it does manifest it causes significant morbidity and mortality. This review summarises the existing evidence for its role in sexual transmission and offers suggestions for those working in the area of sexual health. This is the third part of a series looking at novel sexually transmitted infections.

Noninvasive Detection of Antibodies to Human T-Cell Lymphotropic Virus Types 1 and 2 by Use of Oral Fluid

Human T-lymphotropic viruses type 1 and 2 (HTLV-1/2) are prevalent in endemic clusters globally, and HTLV-1 infects at least 5 to 10 million individuals. Infection can lead to inflammation in the spinal cord, resulting in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), or adult T cell leukemia/lymphoma (ATL). Obtaining venous blood for serological screening, typically performed using enzyme immunoassays (EIAs), is invasive, sometimes socially unacceptable, and has restricted large-scale seroprevalence studies. Collecting oral fluid (OF) is a noninvasive alternative to venesection. In this study, an IgG antibody capture EIA was developed and validated to detect anti-HTLV-1/2 IgG in OF. OF and plasma specimens were obtained from seropositive HTLV-1/2-infected patients attending the National Centre for Human Retrovirology (n = 131) and from HTLV-1/2-uninfected individuals (n = 64). The assay showed good reproducibility and high diagnostic sensitivity (100%) and specificity (100%) using both OF and plasma. The Murex HTLV I+II commercial assay was evaluated and did not detect anti-HTLV-1/2 IgG in 14% (5/36) of OF specimens from seropositive donors. The reactivities of OF and plasma in the IgG capture correlated strongly (r = 0.9290) and were not significantly affected by delayed extraction when held between 3°C and 45°C for up to 7 days to simulate field testing. The use of OF serological screening for HTLV-1/2 infection could facilitate large-scale seroprevalence studies, enabling active surveillance of infection on a population level.

Pregnancy outcomes and mother-to-child transmission rate in HTLV-1/2 infected women attending two public hospitals in the metropolitan area of Rio de Janeiro

HTLV-1/2 are transmitted sexually, by whole cell blood products and from mother-to-child (MTC), mainly through breastfeeding. HTLV-1/2 prevalence in pregnant women is high in Rio de Janeiro, however there were no local studies addressing the rate of adverse pregnancy outcomes (APO) and MTC transmission. The aim was to study sociodemographic characteristics which may be associated to HTLV-1/2 infection and describe pregnancy outcomes and MTC transmission in HTLV-1/2-positive women. The cross-sectional study screened 1,628 pregnant women in of Rio de Janeiro (2012–2014) and found 12 asymptomatic carrier mothers (prevalence = 0.74%). Pregnancy outcome information was retrieved from medical records. Sociodemographic characteristics were similar between the positive and negative groups except for maternal age, which was higher in carrier mothers. The incidence of adverse pregnancy outcomes was similar in infected and non-infected patients (p = 0.33), however there was a high rate of premature rupture of membranes (PROM) amid infected mothers (3/12). Multilevel logistic regression found that for each additional year of age, the chance of being HTLV-1/2-positive increased 11% and that having another sexually transmitted infection (STI) increased 9 times the chance of being infected. Carrier mothers had more antenatal visits (OR = 5.26). Among the children of HTLV-1/2-positive mothers there was one fetal death, one infant death and one loss of follow-up. After two years of follow-up there was one case of MTC transmission (1/9). The mother reported breastfeeding for one month only. Knowledge about factors associated to HTLV-1/2 infection, its impact on pregnancy outcomes and the MTC transmission rate is important to guide public health policies on antenatal screening and management.

HTLV-1/2 are retroviruses transmitted by sex, blood products and from mother to child (MTC), mainly through breastfeeding. There is currently no vaccine, treatment or cure. Although it’s mostly asymptomatic it can cause disabling and even lethal diseases in carriers. The prevalence of HTLV-1/2 in pregnant women at the metropolitan area of Rio de Janeiro is high (0.74%). Our aim was to study the sociodemographic characteristics which may be associated to HTLV-1/2 infection and describe pregnancy outcomes and MTC transmission in the infected population. Apart from being slightly older, there were no differences in the carrier mothers’ sociodemographic profile. Pregnant women with sexually transmitted infections had a 9-fold chance of being HTLV-1/2 positive. Although adverse pregnancy outcomes were not increased, infected mothers had a high rate of ruptured membranes. Among the children of HTLV-1/2-positive mothers there was one fetal death, one infant death and one loss of follow-up. There was one case of MTC transmission (1/9), after one month of breastfeeding. Knowledge about factors associated to HTLV-1/2 infection, its impact on pregnancy, and the MTC transmission rate is important to guide further research and public health policies.

Association Between HTLV-1 Genotypes and Risk of HAM/TSP

Human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a neurological disorder presenting with spastic paraparesis, sphincter dysfunction, and mild sensory disturbance in the lower extremities, which develops in a small minority of HTLV-1-infected individuals. HTLV-1-specific T cells are efficiently activated through dedicated human leukocyte antigen-mediated mechanisms, a process considered deeply involved with its pathogenesis. It has been reported that the lifetime risk of developing HAM/TSP differs between ethnic groups, and there is an association between HTLV-1 tax gene subgroups (i.e., tax subgroup-A or -B), which correspond to HTLV-1 “cosmopolitan subtype 1a subgroup A (i.e., transcontinental subgroup)” and “cosmopolitan subtype 1a subgroup B (i.e., Japanese subgroup),” respectively, and the risk of HAM/TSP in the Japanese population. These findings suggest that a given host’s susceptibility to HAM/TSP is deeply connected with both differences in genetically determined components of the host immune response and HTLV-1 subgroup. Therefore, it is crucial for ongoing work to focus on developing novel treatments and preventative approaches for HAM/TSP. In this review, based on an overview of the topic and our latest research findings, the role of the HTLV-1 subgroup on the effects of virus–host interactions in the pathogenesis of HAM/TSP is discussed.