Comparative performances of serologic and molecular assays for detecting human T lymphotropic virus type 1 and type 2 (HTLV-1 and HTLV-2) in patients infected with human immunodeficiency virus type 1 (HIV-1)

Low-cost and simple PCR process for access to molecular diagnosis of HTLV-1/2 in low-resource countries

BACKGROUND

HTLV-1/2 exhibit a widespread distribution globally and are associated with severe clinical manifestations, necessitating precise viral identification for diagnosis. Currently, there are no official diagnostic guidelines, and a variety of published protocols exists. We introduce an enhanced nested real-time PCR technique followed by high-resolution melting (rtPCR-HRM), designed to offer a cost-effective and straightforward tool for the simultaneous identification of both viruses.

METHODS

The technique was tested in a retrospective, blinded study, involving a total panel of 110 samples, of which 47 were positive for HTLV-1, 12 for HTLV-2, and 51 tested negatives. Additionally, we compared the performance of this technique with a line immunoassay (LIA).

RESULTS

The results demonstrate 100 % sensitivity, specificity, and diagnostic accuracy for both viruses. Sensitivity analysis indicated that at least 1 viral copy of HTLV-1 and 14.4 viral copies of HTLV-2 could be reliably detected.

CONCLUSIONS

Our results indicate that rtPCR-HRM is effective in confirming HTLV-1 and HTLV-2 infection, important in Latin American countries where both viruses circulate. Furthermore, the proposed strategy provides a new tool that can be used to resolve indeterminate cases identified by Western blot, with the added advantage of being faster and simpler than n-PCR and more cost-effective than other probe-based RT-PCRs.

Molecular and Phylogenetic Evidence of Interfamilial Transmission of HTLV-1 in the Afro-Descendant Community of São José de Icatú in the Brazilian Amazon

This study aimed to describe the prevalence of HTLV-1/2 in quilombola communities in the state of Pará and investigate the possible sociodemographic risk factors associated with the infection, as well as to trace the occurrence of the familial transmission of the virus. A total of 310 individuals living in eight quilombos located in the state of Pará (northern Brazil) were investigated for the presence of anti-HTLV-1/2 antibodies using an enzyme-linked immunosorbent assay (ELISA), and positive samples were confirmed using Western blot and/or real-time quantitative polymerase chain reaction (qPCR). Participants answered a questionnaire about sociodemographic aspects and risk factors for infection. Anti-HTLV-1/2 antibodies were detected in two individuals (one man and one woman), for an overall seroprevalence of 0.65%. Both individuals belonged to the community of São José de Icatú. The search for intrafamilial infection identified two other infected women, which increased the general prevalence of HTLV-1 among the Icatú to 6.25% (4/64). Western blot and qPCR confirmed their HTLV-1 infection, and phylogenetic analysis demonstrated that the isolates were of the cosmopolitan subtype and transcontinental subgroup. Epidemiological investigation of the cases revealed that the three women, at some point in their lives, had a relationship with the infected male individual. HTLV-1 is transmitted silently between individuals in the community of São José de Icatú with a present or past family relationship, stressing the need for screening and laboratory diagnosis to prevent further dissemination of the virus and surveillance of disease emergence.

Evaluation of the New Multi-HTLV Serological Assay: Improvement for HTLV-2 Detection

Despite the accuracy of confirmatory tests for the diagnosis of human T cell lymphotropic virus (HTLV), inconclusive or false-negative results still occur when diagnosing human T cell lymphotropic virus type 2 (HTLV-2)-positive patients. The goal of this study was to evaluate the sensitivity and accuracy of a confirmatory immunoassay, the Multi-HTLV assay. A total of 246 plasma samples were tested by real-time polymerase chain reaction (qPCR) and used to calculate the sensitivity and typing accuracy of the Multi-HTLV assay. Of the 246 plasma samples, 127 were positive for human T cell lymphotropic virus type 1 (HTLV-1), 112 were positive for HTLV-2, and 7 were positive for both HTLV-1 and HTLV-2. Thereafter, the nonparametric Mann-Whitney U test was used to calculate the concordance between the qPCR test and Multi-HTLV assay in 12 samples with discrepant and inconclusive qPCR results. The Multi-HTLV assay showed high performance in identifying HTLV-1 and HTLV-2 with sensitivities of 97% [95% confidence interval (CI): 0.92-0.98] and 94% (0.87-0.96), respectively. However, due to typing performance (98% for HTLV-1 and 94% for HTLV-2), it had 95% agreement with positive HTLV-1 qPCR results (95% CI: 90.07-97.81) and 86% (78.04-91.01) of HTLV-2 qPCR results were positive. Moreover, this test was able to recognize 80% of indeterminate samples and all HTLV-2 positive samples that showed false-negative qPCR results. Our findings, derived from a substantial number of HTLV-positive samples, underscore the inherent reliability and feasibility of the Multi-HTLV assay, regardless of the molecular testing facilities. Furthermore, the distinctive multiparametric nature of this assay, combined with its straightforward procedural execution, introduces novel perspectives for analyzing specific serological profiles in each patient, as well as the potential for immunological monitoring of disease progression.

Comparison of two new HTLV-I/II screening methods, Abbott Alinity i rHTLV-I/II and Diasorin LIAISON® XL murex recHTLV-I/II, to Abbott architect rHTLVI/II assay

BACKGROUND

Diagnosis of Human T-cell Lymphotropic Virus (HTLV) types I and II infection requires sequencial testing with firstly a screening using an Enzyme immunoassay followed by a confirmatory test.

OBJECTIVES

To compare the performances of the Alinity i rHTLV-I/II (Abbott®) and LIAISON® XL murex recHTLV-I/II serological screening tests to the ARCHITECT rHTLVI/II test followed if positive by HTLV BLOT 2.4, MP Diagnostics as the reference.

STUDY DESIGN

119 serum samples from 92 known HTLV-I infected patients and 184 from uninfected patients with HTLV were analyzed in parallel with, Alinity i rHTLV-I/II, LIAISON® XL murex recHTLV-I/II and ARCHITECT rHTLVI/II.

RESULTS

Alinity i rHTLV-I/II and LIAISON® XL murex recHTLV-I/II exhibited a total agreement with ARCHITECT rHTLVI/II for both positive and negative samples. Both tests are suitable alternatives for HTLV screening.

Development and validation of a duplex real-time PCR for the rapid detection and quantitation of HTLV-1

BACKGROUND

The HTLV-1 prevalence in China varies geographically, while HTLV-2 infection has rarely been found so far. Proviral load is one of the determining factors of pathogenesis and progression of HTLV-1 related diseases. However, neither molecular assays nor commercial kits are available for HTLV-1 diagnosis in China. The objective of the present study was to develop and validate a TaqMan qPCR assay for HTLV-1 proviral load quantification.

RESULTS

A plasmid containing both the HTLV-1 of interest and a fragment of the RNase P (RPPH1) gene was constructed and used to establish the standard curves. The assay has a wide dynamic range (2.5 × 10⁸ copies/reaction ~ 25 copies/reaction) and sensitive to 1 copy for HTLV-1 and RPPH1. The limit of detection for Hut102 cell concentration was 0.0218% (95% confidence interval 0.0179-0.0298%). The assay gave coefficient of variation (CV) for both the HTLV-1 and RPPH1 Ct values. All of the HTLV-1 sero-negative samples and MOT cell line (infected with HTLV-2) amplified only the RPPH1 gene by our method, presenting 100% specificity. 85 Samples confirmed positive or indeterminate by LIA were performed by established qPCR assay and WB. 90.0% (27/30) of LIA-HTLV-1-positive, 33% (2/6) of LIA-untypeable and 2% (1/49) of LIA-indeterminate samples were defined as qPCR-positive. The median PVL of LIA-positive samples (n = 27, 1.780 copies/100 cells) was much higher than that of LIA-untypeable and (n = 2, 0.271 copies/100 cells) indeterminate samples (n = 1, 0.017 copies/ 100 cells). Additionally, compared to WB, the duplex qPCR verified more positive samples, demonstrating a better sensitivity.

CONCLUSION

The duplex qPCR developed here with high sensitivity, good specificity and reproducibility could accurately and quantitatively detect the HTLV-1 PVLs, which can be used to confirm the initial reactive samples for an improved cost/benefit ratio as well as to monitor the clinical progression and efficacy of therapy in patients with HTLV-1 related disease.

Human T Lymphotropic Virus 1-Associated Myelopathy: Overview of Human T Cell Lymphotropic Virus-1/2 Tests and Potential Biomarkers

Human T cell lymphotropic virus (HTLV)-1-associated myelopathy is a chronic, disabling inflammatory disorder of the spinal cord caused by HTLV-1 infection. The diagnosis of HTLV-1-associated myelopathy (HAM) is based on clinical and laboratorial findings. The disease is characterized by the presence of spastic paraparesis associated with detection of anti-HTLV-1 antibodies or HTLV-1 genomes in blood and cerebrospinal fluid (CSF). New inflammatory markers have been proposed for the diagnosis and assessment of the prognosis of HAM. We reviewed the laboratory diagnostic and potential surrogate markers for HAM. The serological screening tests for detection of anti-HTLV-1/2 antibodies are highly sensitive and specific, but confirmation and typing of HTLV-1 or HTLV-2 infection by other serological or molecular methods are essential. Detection of intrathecal anti-HTLV-1 antibodies and quantification of the HTLV-1 provirus in CSF provide additional evidence for diagnosis especially in atypical cases or where alternative causes of neuroinflammation cannot be excluded. The CXC motif chemokine ligand 10 and neopterin in serum and CSF are now emerging as inflammatory markers with prognostic value and for HAM monitoring and management. In addition, measures of neurodegeneration, such as neurofilament light chain in the CSF and blood, may also contribute to the HAM prognosis. This review is useful for clinicians and researchers evaluating potential benefits and limitations of each biomarker in clinical practice. The advent of new markers makes it necessary to update the criteria for the best evidence-based approach and for worldwide consensus regarding the use of diagnostic and surrogate markers for HAM.

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.

Development and Validation of Multiplex Quantitative Real-Time PCR Assays for Simultaneous Detection and Differentiation of HTLV-1 and HTLV-2, Using Different PCR Platforms and Reagent Brands

Brazil currently has the highest number of individuals infected with human T-lymphotropic virus 1- and 2- (HTLV-1 and HTLV-2) globally. At present, neither molecular protocols nor commercial assays are available for HTLV-1/-2 diagnosis or validated by the Brazilian Ministry of Health regulatory agency (ANVISA). We developed and validated two in-house multiplex quantitative real-time PCR for HTLV-1/-2 (mqPCR_HTLV) assays, targeting the pol and tax genes, for the simultaneous identification of HTLV-1, HTLV-2, and the albumin reference gene. The robustness of the assays was evaluated on two platforms using seven commercial master mix formulations. The reactions employed double plasmids (pHTLV1-Alb and pHTLV2-Alb) for the standard curve’s construction and for expressing the detection limit of the assays. They were able to detect 10 and 10 copies of HTLV-1 and 10 and 70 copies of HTLV-2 for the tax and pol targets, respectively. High efficiency was obtained using both the platforms and all the reagents evaluated and were successfully reproduced by other analysts. DNA samples from HTLV-1/-2-infected and non-infected patients and from HIV/HTLV-coinfected patients were evaluated to determine the feasibility of their use in routine diagnosis. The mqPCR_HTLV (pol and tax) assays demonstrated an overall specificity of 100% and a sensitivity of 97.4% when testing samples from patients without HIV infection, and sensitivities of 77.1% (pol) and 74.6% (tax) in samples from HIV/HTLV-coinfected patients. In addition, they resolved the issue of HTLV western blotting (WB) indeterminate and WB-untyped results in 45.5 and 66.7% of cases, respectively. The developed mqPCR_HTLV (pol and tax) assays indicated their feasibility for efficient and reliable HTLV diagnosis in various core facility laboratories under different conditions and supplies.

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.

HTLV viruses are responsible for more than 10 million cases of infection worldwide. The infection is considered as a neglected disease due to lack of vaccines and treatments. Accurate diagnosis is crucial for counselling infected persons and prevention of secondary transmissions. In spite of the development of excellent serological screening assays, many cases of indeterminate and untyped results are still regularly reported and their infection status remain uncertain. To address the need of more precise diagnosis, we have developed a new cutting-edge in-vitro diagnostic confirmation test, named Multi-HTLV, which has been validated on a large panel of HTLV samples. The test is a multiplex immunoassay allowing powerful detection of antibodies against HTLV through combination of a set of selective and validated virus-specific antigens in a blood sample. The Multi-HTLV assay increases the reliability of HTLV diagnostics and strain typing thanks to a high precision mathematical algorithm.

Epidemiological and molecular profile of blood donors infected with HTLV-1/2 in the state of Pará, northern Brazil

BACKGROUND

The Human T-lymphotropic virus (HTLV) is a retrovirus of the genus Deltaretrovirus, which belongs to the family Retroviridae. The most important types are HTLV-1 and HTLV-2. It is estimated that between five and 10 million individuals are infected with HTLV-1, worldwide. Studies in the state of Pará indicate that it has the third highest prevalence of HTLV infections of any Brazilian state. The present study describes the epidemiological, serological, and molecular profile of blood donors from the state of Pará that were classified as unfit due to infection by HTLV-1 and 2.

METHODS

The present study is based on a descriptive, retrospective, and cross-sectional review of the epidemiological, serological, and molecular data on blood donations, between January 2015 and December 2019. The data were obtained from the blood bank system and were digitalized to form a database in the Statistical Package for Social Sciences program, version 20. Descriptive statistics were used to determine the absolute and relative frequencies of the qualitative variables. For the quantitative variables, the mean, standard deviation, and minimum and maximum values were calculated. A p < 0.05 significance level was adopted for all analyses.

RESULTS

A total of 632 samples were analyzed, of which 496 (78%) had no detectable proviral DNA and 136 (22%) had detectable HTLV. The HTLV-1 was detected in most (78%; 106/136) of these samples, while only 30 (22%) were detected for HTLV-2. The HTLV proviral DNA was detected primarily in females (69.1%), with a mean age of 40 years, with the highest frequencies of detection being recorded in single individuals (66.2%), first-time donors (74.3%), and individuals that had graduated high school (44.1%). The molecular confirmation of HTLV showed that three-quarters (78%) of the serologically reactive individuals were negative for either types 1 or 2, so the epidemiological profile of these individuals was significantly different from their detectable profile.

CONCLUSIONS

The HTLV is neglected in Brazil; there is thus a clear need for further research in the area of regional hemotherapy and hematology services, in order to contribute to the definition of regional infection profiles, that will be fundamental to the development of effective prophylactic practices for the prevention of the infection and the dissemination of knowledge on the dangers of HTLV in the community.

Work-Related Human T-lymphotropic Virus 1 and 2 (HTLV-1/2) Infection: A Systematic Review

Human T-lymphotropic virus 1 and 2 (HTLV-1/2) belong to the delta group of retroviruses which may cause a life-long infection in humans, HTLV-1 leading to adult T-cell leukemia/lymphoma and other diseases. Different transmission modes have been described, such as breastfeeding, and, as for other blood-borne pathogens, unsafe sexual activity, intravenous drug usage, and blood transfusion and transplantation. The present systematic review was conducted to identify all peer-reviewed studies concerning the work-related infection by HTLV-1/2. A literature search was conducted from January to May 2021, according to the PRISMA methodology, selecting 29 studies: seven related to health care workers (HCWs), five to non-HCWs, and 17 to sex workers (SWs). The findings showed no clear evidence as to the possibility of HTLV-1/2 occupational transmission in HCWs, according to the limited number and quality of the papers. Moreover, non-HCWs showed a higher prevalence in jobs consistent with a lower socioeconomic status or that could represent a familial cluster, and an increased risk of zoonotic transmission from STLV-1-infected non-human primates has been observed in African hunters. Finally, a general increase of HTLV-1 infection was observed in SWs, whereas only one paper described an increased prevalence for HTLV-2, supporting the urgent need for prevention and control measures, including screening, diagnosis, and treatment of HTLV-1/2, to be offered routinely as part of a comprehensive approach to decrease the impact of sexually transmitted diseases in SWs.

Laboratory diagnosis of human T-lymphotropic virus in Brazil: assays, flowcharts, challenges, and perspectives

INTRODUCTION

We present a data analysis and review of recent studies regarding the laboratory diagnosis of human T-lymphotropic virus 1 and 2 (HTLV-1/2) infections in Brazil.

METHODS

Target populations, available diagnostic serological assays (screening and complementary tests), molecular assays (in-house), causes of false-positive and false-negative results, and flowcharts were analyzed.

RESULTS

A table presents the target populations, two diagnostic flowcharts (depending on laboratory infrastructure and study population), and recent research that may improve how HTLV-1/2 is diagnosed in Brazil.

CONCLUSIONS

Our results support the implementation of public policies to reduce HTLV-1/2 transmission and its associated diseases.

Brazilian Protocol for Sexually Transmitted Infections 2020: human T-cell lymphotropic virus (HTLV) infection

This article addresses the Human T-lymphotropic virus (HTLV). This subject comprises the Clinical Protocol and Therapeutic Guidelines for Comprehensive Care for People with Sexually Transmitted Infections, published by the Brazilian Ministry of Health. HTLV-1/2 infection is a public health problem globally, and Brazil has the largest number of individuals living with the virus. HTLV-1 causes several clinical manifestations of neoplasm (adult T-cell leukemia/lymphoma) and inflammatory nature, such as HTLV-1-associated myelopathy and other manifestations such as uveitis, arthritis, and infective dermatitis. These pathologies have high morbidity and mortality and negatively impact the quality of life of infected individuals. This review includes relevant information for health authorities professionals regarding viral transmission, diagnosis, treatment, and monitoring of individuals living with HTLV-1 and 2 in Brazil. HTLV-1/2 transmission can occur through blood transfusion and derivatives, injectable drug use, organ transplantation, unprotected sexual intercourse, and vertical transmission.

[Brazilian Protocol for Sexually Transmitted Infections 2020: human T cell lymphotropic virus (HTLV) infection]

This manuscript is related to the chapter about human T-cell lymphotropic virus (HTLV) that is part of the Clinical Protocol and Therapeutic Guidelines for Comprehensive Care for People with Sexually Transmitted Infections, published by the Brazilian Health Ministry. HTLV-1/2 infection is a worldwide public health problem and Brazil has the largest number of individuals living with the virus. HTLV-1 causes a variety of clinical manifestations of a neoplastic nature, such as adult leukemia/T-cell lymphoma, and also of an inflammatory nature, such as HTLV-1-associated myelopathy, as well as other manifestations such as uveitis, arthritis and infective dermatitis. These pathologies have high morbidity and mortality and negatively impact the quality of life of infected individuals. This review includes relevant information for health service managers and workers regarding virus transmission modes, diagnosis, treatment and monitoring of individuals living with HTLV-1 and 2 in Brazil.

Seroprevalence and Trends of HTLV-1/2 among Blood Donors of Santo Domingo, Dominican Republic, 2012-2017

OBJECTIVE

Being a Caribbean country, the Dominican Republic is considered endemic for HTLV-1. Viral screening in blood banks is recommended for this blood borne infection. The purpose of this work is to analyze the seroprevalence and trends of HTLV-1/2 in the Dominican Republic blood donors; it is focused on Santo Domingo, the capital of the country, which has the largest blood donation activity. We also aim at comparing our findings with published data from neighboring countries.

METHODS

We performed a retrospective cross-sectional study of 10 blood centers of Santo Domingo, which reported HTLV and the other blood-transmitted infections in full. They represent more than 40% of the province's blood donations. Annual seroprevalence of HTLV-1/2, period prevalence (2012-2017), and time trend were determined.

RESULTS

A total of 352,960 blood donations were evaluated. The HTLV-1/2 period prevalence was 0.26% (929/352,960)(95% CI: 0.24-0.28%). We also found a marked predominance of replacement donation (90.4%) in comparison to voluntary contributions (9.6%). Therefore, this blood donor study may provide clues on the general prevalence of the infection.

CONCLUSIONS

Seroprevalence of HTLV-1/2 in blood donors of Santo Domingo, Dominican Republic, showed a relatively low and steady trend in the studied period.

Provirus Mutations of Human T-Lymphotropic Virus 1 and 2 (HTLV-1 and HTLV-2) in HIV-1-Coinfected Individuals

Provirus mutations of human T-lymphotropic virus 1 (HTLV-1), mostly the lack of the 5' long terminal repeat (LTR) genomic region, have been described and associated with severe adult T cell leukemia/lymphoma (ATLL), non-sense point mutations with low proviral load, and Western blotting indeterminate results. Until now, no information concerning provirus mutations of HTLV-2 and its consequences, as well as those of HTLV-1/2 in HIV-coinfected individuals, had been described. Therefore, we searched for these mutations in provirus samples of 44 HIV/HTLV-1- and 25 HIV/HTLV-2-coinfected individuals. Using protocols well established for amplification and sequencing of segments of the LTR, env, and tax regions, we searched for defective type 1 particles that retain LTRs and lack internal sequences and type 2 particles that lack the 5'LTR region. In addition, using as references the prototypes ATK (HTLV-1) and Mo (HTLV-2), we searched for point mutations in the LTR and synonyms and nonsynonymous mutations and non-sense mutations in env and tax regions. Defective HTLV-1 and HTLV-2 provirus type 1 or 2 was detected in 31.8% of HIV/HTLV-1- and 32.0% of HIV/HTLV-2-coinfected individuals. Synonymous and nonsynonymous mutations were identified mostly in HTLV-2 and associated with lower levels of specific antibodies. No non-sense mutations that resulted in premature termination of Env and Tax proteins were detected. On the contrary, mutation in the stop codon of Tax2a produced a long protein characteristic of the HTLV-2c subtype. The clinical significance of these mutations in coinfected individuals remains to be defined, but they confirmed the lower sensitivity of serological and molecular diagnostic tests in HIV/HTLV-1/2 coinfections.IMPORTANCE HTLV-1 and HTLV-2 are endemic to Brazil, and they have different effects in HIV/AIDS disease progression. HIV/HTLV-1 has been described as accelerating the progression to AIDS and death, while HIV/HTLV-2 slows the progression to AIDS. Provirus mutations of HTLV-1 were implicated in severe leukemia development and in problems in the diagnosis of HTLV-1; in contrast, provirus mutations of HTLV-2 had not been confirmed and associated with problems in HTLV-2 diagnosis or disease outcome. Nevertheless, data obtained here allowed us to recognize and understand the false-negative results in serologic and molecular tests applied for HTLV-1 and HTLV-2 diagnosis. Defective proviruses, as well as synonymous and nonsynonymous mutations, were associated with the diagnosis deficiencies. Additionally, since HIV-1 and HTLV-1 infect the same cells (CD4 positive), the production of HIV-1 pseudotypes with HTLV-1 envelope glycoprotein during HIV/HTLV-1 coinfection cannot be excluded. Defective provirus of HTLV-2 and Tax2c is speculated to influence progression to AIDS.

Loop-Mediated Isothermal Amplification (LAMP) Assay for Rapid and Accurate Confirmatory Diagnosis of HTLV-1/2 Infection

Laboratory diagnosis of human T-lymphotropic viruses (HTLV) 1 and 2 infection is performed by serological screening and further confirmation with serological or molecular assays. Thus, we developed a loop-mediated isothermal nucleic acid amplification (LAMP) assay for the detection of HTLV-1/2 in blood samples. The sensitivity and accuracy of HTLV-1/2 LAMP were defined with DNA samples from individuals infected with HTLV-1 (n = 125), HTLV-2 (n = 19), and coinfected with HIV (n = 82), and compared with real-time polymerase chain reaction (qPCR) and PCR-restriction fragment length polymorphism (RFLP). The overall accuracy of HTLV-1/2 LAMP (95% CI 74.8-85.5%) was slightly superior to qPCR (95% CI 69.5-81.1%) and similar to PCR-RFLP (95% CI 79.5-89.3%). The sensitivity of LAMP was greater for HTLV-1 (95% CI 83.2-93.4%) than for HTLV-2 (95% CI 43.2-70.8%). This was also observed in qPCR and PCR-RFLP, which was associated with the commonly lower HTLV-2 proviral load. All molecular assays tested showed better results with samples from HTLV-1/2 mono-infected individuals compared with HIV-coinfected patients, who present lower CD4 T-cell counts. In conclusion, HTLV-1/2 LAMP had similar to superior performance than PCR-based assays, and therefore may represent an attractive alternative for HTLV-1/2 diagnosis due to reduced working time and costs, and the simple infrastructure needed.

The reasons to include the serology of human T-lymphotropic virus types 1 and 2 (HTLV-1 and HTLV-2) in the clinical follow-up of patients with viral hepatitis B and C in Brazil

Background

The WHO established targets for 2030 to globally reduce new viral hepatitis B and C infections by 90% and deaths by 65% and recommends searching for coinfections that increase the progression of chronic liver infections towards cirrhosis and hepatocellular carcinoma.

Aims and methodology

This study aimed to add information concerning the influence of human T-lymphotropic virus type 1 (HTLV-1) and type 2 (HTLV-2) infections in hepatitis B and C, since in Brazil, these human retroviruses are endemic but neglected. Serum samples from 1,910 patients with hepatitis B and 1,315 with hepatitis C from São Paulo, southeast Brazil, that were previously tested and grouped for HIV and HTLV-1/-2 coinfections were analyzed for hepatitis B virus (HBV) and hepatitis C virus (HCV) loads measurements and subsequent clearance using data from laboratory records.

Key results

Briefly, the lowest HBV viral load (VL) was detected in HBV/HTLV-2 coinfected patients, regardless of whether they were infected with HIV (all comparisons p<0.05). In contrast, higher HCV VL was detected in HCV/HIV, HCV/HIV/HTLV-1/-2 coinfected patients (all p<0.05), and the lowest HCV VL was detected in HCV/HTLV-2 coinfected patients. Curiously, 61.1% of the patients with HBV/HTLV-2 coinfection had an undetectable HBV VL at the beginning of the study versus 21.4% in the patients with HBV/HTLV-1 coinfection. Although the percentages of undetectable HCV loads in HCV/HTLV-1 and HCV/HTLV-2 coinfected patients were quite similar, during follow-up, more HCV clearance was detected in patients with HCV/HTLV-2 coinfection [OR 2.65; 95% IC (1.17–5.99)].

Major conclusions

HTLV-2 positively impacts HBV and HCV viral loads and HCV clearance, while HIV and/or HTLV-1 negatively impacts HCV viral load. Thus, the search for HTLV-1/-2 in viral hepatitis B and C infected patients has virological prognostic value, which is a strong reason to suggest including HTLV serology in the follow-up of patients.

The human T-lymphotropic viruses type 1 (HTLV-1) and type 2 (HTLV-2) are endemic and neglected in Brazil, and although these viruses were considered to have prognostic value when associated with HIV, e.g., HTLV-1 has been associated with fast progression and death to AIDS and more cases of lymphoma and neurological disorders, and HTLV-2 has been associated with slow progression to AIDS, their impact on hepatitis B virus (HBV) and hepatitis C virus (HCV) outcomes remain unknown. The present study analyzed the influence of HTLV-1 and HTLV-2 coinfection on HBV and HCV virological outcomes (viral load levels and virus clearance during follow-up) in serum samples from 1,910 patients with hepatitis B and 1,315 patients with hepatitis C from São Paulo, southeast Brazil. The results obtained confirmed the positive impact of HTLV-2 on HBV and HCV virological outcomes (lower HBV and HCV viral loads and increased HCV clearance when compared with HCV-monoinfected patients) and the opposite effect of HTLV-1; these findings are similar to the effects observed in HIV/AIDS patients. Taking into consideration these results and the differential impact of HTLV-1 and HTLV-2 in viral hepatitis B and C, we suggest including the serology of HTLV-1/2 in the follow-up of such patients in Brazil.

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.

Surveillance of human retroviruses in blood samples from patients with hepatitis B and C in São Paulo, Brazil

INTRODUCTION

Human retroviruses and the hepatitis B and C viruses (HBV and HCV, respectively) share routes of transmission; thus, coinfections occur and could alter subsequent disease outcomes. A preliminary study on human T-lymphotropic virus types 1 and 2 (HTLV-1/2) in serum samples from HBV- and HCV-infected individuals in São Paulo revealed 1.3% and 5.3% rates of coinfection, respectively. These percentages were of concern since they were detected in HTLV-endemic regions and in high-risk individuals in Brazil. The present study was conducted to extend and confirm these data.

METHODS

HTLV-1/2 and human immunodeficiency virus (HIV) infection status were identified in 1,984 sera for HBV and HCV viral load quantification - 1,290 samples from HBV-infected individuals (53.3% men, mean age: 47.1 years) and 694 samples from HCV-infected individuals (56.3% men, mean age: 50.1 years). HTLV-1/2 antibodies were detected by enzyme immunoassay, followed by western blotting and line immunoassay; HIV infection was detected by enzyme immunoassay.

RESULTS

HTLV-1/-2 infection was detected in 1.9% HBV-infected individuals (0.7% HTLV-1 and 1.2% HTLV-2) and in 4.0% (2.4% HTLV-1 and 1.6% HTLV-2) HCV-infected individuals; HIV infection was detected in 9.2% and 14.5%, respectively. Strong associations with HTLV and HIV, male sex, and older age were found in HBV/HTLV and HCV/HTLV-coinfected individuals (p<0.05).

CONCLUSIONS

HTLV-1 and HTLV-2 were confirmed to be prevalent in individuals with HBV and HCV in São Paulo; coinfected individuals deserve further clinical and laboratory investigation.

Line Immunoassay for Confirmation and Discrimination of Human T-Cell Lymphotropic Virus Infections in Inconclusive Western Blot Serum Samples from Brazil

Difficulties in confirming and discriminating human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infections by serological Western blot (WB) assays (HTLV Blot 2.4; MP Biomedicals) have been reported in Brazil, mainly in HIV/AIDS patients, with a large number of WB-indeterminate and WB-positive but HTLV-untypeable results. Nonetheless, a line immunoassay (LIA) (INNO-LIA HTLV-I/II; Fujirebio) provided enhanced specificity and sensitivity for confirming HTLV-1/2 infections.

Difficulties in confirming and discriminating human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 infections by serological Western blot (WB) assays (HTLV Blot 2.4; MP Biomedicals) have been reported in Brazil, mainly in HIV/AIDS patients, with a large number of WB-indeterminate and WB-positive but HTLV-untypeable results. Nonetheless, a line immunoassay (LIA) (INNO-LIA HTLV-I/II; Fujirebio) provided enhanced specificity and sensitivity for confirming HTLV-1/2 infections. To add information concerning the improved ability of the LIA in relation to WB when applied to samples of individuals from different risk groups from Brazil, we performed the present study. Three groups were analyzed: group 1 (G1), with 62 samples from HIV/AIDS patients from São Paulo, SP (48 WB indeterminate and 14 HTLV untypeable); group 2 (G2), with 24 samples from patients with hepatitis B or hepatitis C from São Paulo (21 WB indeterminate and 3 HTLV untypeable; 17 HIV seropositive); and group 3 (G3), with 25 samples from an HTLV outpatient clinic in Salvador, Bahia (16 WB indeterminate and 9 HTLV untypeable; all HIV seronegative). Overall, the LIA confirmed HTLV-1/2 infection (HTLV-1, HTLV-2, or HTLV) in 66.1% (G1), 83.3% (G2), and 76.0% (G3) of samples. Interestingly, the majority of WB-indeterminate results were confirmed by the LIA as being HTLV-2 positive in G1 and G2 but not in G3, in which the samples were defined as being HTLV-1 or HTLV positive. These results agree with the virus types that circulate in such patients of different regions in Brazil and emphasize that the LIA is the best serological test for confirming HTLV-1 and HTLV-2 infections, independently of being applied in HTLV-monoinfected or HTLV-coinfected individuals.

The first survey of human T-cell lymphotropic viruses (HTLV) in HIV/AIDS patients in Santa Catarina State, Brazil

Santa Catarina is a Brazilian State that has reported the lowest prevalence of human T-cell lymphotropic viruses (HTLV-1/2) in blood donors (0.04%). Although it presents ports, airports and roads that facilitate the entrance and dissemination of new infectious agents, no information exists concerning the HTLV-1/2 infections in HIV/AIDS patients. This study searched for HTLV-1/2 antibodies in plasma samples of 625 HIV/AIDS patients from the municipality of Tubarao (Southern Santa Catarina), and disclosed 1.1% of positivity (0.48% HTLV-1, 0.48% HTLV-2 and 0.16% untypeable HTLV), and a positive correlation with the male sex (OR 4.16) and intravenous drug use (OR 35.18). Although the percentage of 1.1% appears to be low, it is 27.5 times higher than the percentage detected in blood donors. Since HTLV-1 and HTLV-2 are circulating in HIV-infected individuals in Southern Santa Catarina, and these retroviruses could cause a differently impact on the HIV/AIDS outcomes, the surveillance of HTLV-1/2 is necessary, and it could support public health policies in preventing the transmission and dissemination of these viruses in this State.

Performance of Commercially Available Serological Screening Tests for Human T-Cell Lymphotropic Virus Infection in Brazil

Serological screening for human T-cell lymphotropic virus type 1 (HTLV-1) is usually performed using enzyme-linked immunosorbent assay (ELISA), particle agglutination, or chemiluminescence assay kits. Due to an antigen matrix improvement entailing the use of new HTLV antigens and changes in the format of HTLV screening tests, as well as newly introduced chemiluminescence assays (CLIAs), a systematic evaluation of the accuracy of currently available commercial tests is warranted. We aimed to assess the performance of commercially available screening tests for HTLV infection diagnosis. A diagnostic accuracy study was conducted on a panel of 397 plasma samples: 200 HTLV-negative plasma samples, 170 HTLV-positive plasma samples, and 27 plasma samples indeterminate by Western blotting (WB). WB-indeterminate samples (i.e., those yielding no specific bands for HTLV-1 and/or HTLV-2) were assessed by PCR, and the results were used to compare agreement among the commercially available ELISA screening tests. For performance analysis, WB-indeterminate samples were excluded, resulting in a final study panel of 370 samples. Three ELISA kits (Murex HTLV-1/2 [Murex], anti-HTLV-1/2 SYM Solution [SYM Solution], and Gold ELISA HTLV-1/2 [Gold ELISA]) and one CLIA kit (Architect rHTLV-1/2) were evaluated. All screening tests demonstrated 100% sensitivity. Concerning the HTLV-negative samples, the SYM Solution and Gold ELISA kits had specificity values of >99.5%, while the Architect rHTLV-1/2 test presented 98.1% specificity, followed by Murex, which had a specificity of 92.0%. Regarding the 27 samples with WB-indeterminate results, after PCR confirmation, all ELISA kits showed 100% sensitivity but low specificity. Accuracy findings were corroborated by the use of Cohen's kappa value, which evidenced slight and fair agreement between PCR analysis and ELISAs for HTLV infection diagnosis. Based on the data, we believe that all evaluated tests can be safely used for HTLV infection screening.

HTLV-1 and -2 in a first-time blood donor population in Northeastern Brazil: Prevalence, molecular characterization, and evidence of intrafamilial transmission

Independent epidemiology for respective human T-cell lymphotropic virus (HTLV) types 1 and 2 is little known in blood donors in Brazil, where screening for HTLV-1/2 is mandatory at blood banks, but no testing to confirm/differentiate these viruses. Therefore, this study aims to assess the prevalence of HTLV-1 and -2 in a first-time blood donor population in Northeastern Brazil and to carry out molecular characterization of respective isolates. A cross-sectional study was conducted at the State Blood Bank in Piauí. Samples were screened for anti-HTLV-1/2 by enzyme immunoassay, and reactive samples were confirmed using a line immunoassay and polymerase chain reaction (PCR). Of 37 306 blood donors, 47 were anti-HTLV-1/2 reactive by enzyme immunoassay. After confirmed by line immunoassay, 22 were positive for HTLV-1 (0.59 per 1000; 95% CI: 0.38-0.87), 14 were positive for HTLV-2 (0.37 per 1000; 95% CI: 0.21-0.61), 1 was indeterminate, and the remaining donors were negative. The HTLV-1 infection was also confirmed by PCR in all anti-HTLV-1-positive samples, and sequencing classified these isolates as belonging to the Transcontinental (A) subgroup of the Cosmopolitan (1a) subtype. Of 14 anti-HTLV-2-positive samples, 11 were also PCR positive, which belonged to subtype a (HTLV-2a/c). In addition, 38 family members of 5 HTLV-1- and 3 HTLV-2-infected donors were analyzed. Familial transmission of HTLV-1 and -2 was evidenced in 3 families. In conclusion, in Northeastern Brazil, where HTLV-1 and -2 are endemic, counseling blood donor candidates and their families might play a key role in limiting the spread of these viruses.

Making the invisible visible: searching for human T-cell lymphotropic virus types 1 and 2 (HTLV-1 and HTLV-2) in Brazilian patients with viral hepatitis B and C

With this study, the authors hope to alert clinicians regarding the presence of human T-cell lymphotropic virus type 1 and 2 (HTLV-1/-2) infections in patients with viral hepatitis B and C in Brazil. HTLV-1/-2 were detected in 1.3% of hepatitis B virus (HBV)- and 5.3% of hepatitis C virus (HCV)-infected blood samples sent for laboratory viral load measurements. A partial association of human immunodeficiency virus (HIV)-1 and HTLV-1/-2 infection was detected in patients with HCV (HIV+, 27.3%), whereas this association was almost 100% in HBV-infected patients (HIV+, all except one). The high prevalence of HTLV-1/-2 infection among patients with hepatitis C was of concern, as HTLV-1/-2 could change the natural course of subsequent liver disease. The authors suggest including HTLV-1/-2 serology in the battery of tests used when following patients with viral hepatitis in Brazil, regardless of the HIV status.