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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., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: LM, PL, MZ are currently employed by INFYNITY BIOMARKERS. The other authors have declared that no competing interests exist.

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., Competing Interests: The authors have declared that no competing interests exist.

Human T-lymphotropic virus type 1 (HTLV-1) infection may cause serious disease, while pathogenicity of HTLV-2 is less certain. There are no screening or surveillance programs for HTLV-1/-2 infection in Brazil. By performing this systematic review, we aimed to estimate the prevalence of HTLV-1/-2 infections in pregnant women in Brazil. This review included cohort and cross-sectional studies that assessed the presence of either HTLV-1/-2 infection in pregnant women in Brazil. We searched BVS/LILACS, Cochrane Library/CENTRAL, EMBASE, PubMed/MEDLINE, Scopus, Web of Science and gray literature from inception to August 2020. We identified 246 records in total. Twenty-six of those were included in the qualitative synthesis, while 17 of them were included in the meta-analysis. The prevalence of HTLV-1 in Brazilian pregnant women, as diagnosed by a positive screening test and a subsequent positive confirmatory test, was 0.32% (95% CI 0.19-1.54), while of HTLV-2 was 0.04% (95% CI 0.02-0.08). Subgroup analysis by region showed the highest prevalence in the Northeast region (0.60%; 95% CI 0.37-0.97) for HTLV-1 and in the South region (0.16%; 95% CI 0.02-1.10) for HTLV-2. The prevalence of HTLV-1 is much higher than HTLV-2 infection in pregnant Brazilian women with important differences between regions. The prevalence of both HTLV-1/-2 are higher in the Northeast compared to Center-West region., (© 2021. The Author(s).)

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.

Background: Human T-cell lymphotropic virus (HTLV) remains a major safety concern for blood supplies. Despite many HTLV positive cases being reported in southeastern China, the detection of HTLV has not been prioritized in routine blood screening. Additionally, data on the prevalence of HTLV infection among blood donors is also limited. The objective of this study was to investigate the prevalence of HTLV among blood donors in three Chinese provinces through their representative blood centers, to evaluate the feasibility of chemiluminescence immunoassay (CLIA) for blood screening., Methods: From November 2018 to March 2019, blood plasma samples were collected from Hebei, Changsha, and Shenzhen blood centers and were screened for the HTLV-1/2 antibody using a CLIA and enzyme-linked immunosorbent assay (ELISA). This was followed by confirmatory tests using INNO-LIA HTLV I/II., Results: A total of 59,929 blood donations were collected and screened for HTLV-1/2. The reactive rate of CLIA and ELISA among donations in the Shenzhen blood center (0.0943%, 27/28,621) was higher than Hebei (0.0248%, 4/16,144), and Changsha (0.0198%, 3/15,164) (p < 0.05). After confirmation, 3 samples were confirmed as indeterminate for HTLV antibodies, and only one sample from the Shenzhen blood center was confirmed as HTLV-1. The overall prevalence of HTLV-1/2 was 1.67 per 100,000 (1/59,929). The HTLV-infected blood came from a 32-year-old first-time female donor with a high school degree, who belonged to the SHE ethnic minority and was born in the Fujian province., Conclusions: In summary, the overall prevalence of HTLV-1/2 among blood donors in the three blood centers in China remains relatively low. However, blood donations with positive or indeterminate results for HTLV antibodies reminded us of the importance of HTLV screening among blood donors in China.

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., (Copyright © 2019 Campos et al.)

The diagnosis of human T -cell leukemia virus type 1 (HTLV-1) infection in Japan is usually performed by serological testing, but the high rate of indeterminate results from western blotting makes it difficult to assess the infection accurately. Nucleic acid tests for HTLV-1 and/or HTLV-2 are used to confirm infection with HTLV-1 and/or HTLV-2 and are also used for the follow-up of HTLV-1 related diseases. To prepare a highly sensitive method that can discern infection with HTLV-1 and HTLV-2, a multiplex quantitative polymerase chain reaction (qPCR) by large-scale primer screening was developed. Sensitivity and specificity were evaluated by serial dilution of cell lines and by testing with known clinical samples. The resulting multiplex qPCR can detect about four copies of HTLV-1 provirus per 10 5 cells. Moreover, HTLV-1 provirus could be detected in 97.2% (205 of 211) of HTLV-1 seropositive clinical samples. These sensitivities were sufficiently high compared with the methods reported previously. Also, all the HTLV-2 seropositive clinical samples tested were found to be positive by this method (three of three). In conclusion, this method can successfully and simultaneously detect both types of HTLV-1 and HTLV-2 provirus with extremely high sensitivity., (© 2019 The Societies and John Wiley & Sons Australia, Ltd.)

Mother-to-child-transmission (MTCT) of human T-cell lymphotropic virus type-1(HTLV-1) contributes disproportionately to the burden of HTLV-1 associated diseases. All preventive measures to avoid MTCT rely on the identification of infected mothers. However, the impact of pregnancy on HTLV-1 diagnosis has not been clearly assessed. Paired samples from 21 HTLV-1 infected women taken during pregnancy and while not pregnant were analysed by CMIA and PCR. The signal-to-cut-off values (S/CO) were higher during pregnancy than in the paired non-pregnant samples. HTLV-1 proviral load did not alter significantly by pregnant state. S/CO positively correlated with HTLV proviral load. Pregnancy does not impair the diagnosis of HTLV-1/2, by either immunological (CMIA) or molecular (qPCR/nPCR) tests., Competing Interests: The authors have declared that no competing interests exist.

Of the members of the primate T cell lymphotropic virus (PTLV) family, only the human T-cell leukemia virus type-1 (HTLV-1) causes disease in humans-as the etiological agent of adult T-cell leukemia/lymphoma (ATLL), HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and other auto-inflammatory disorders. Despite having significant genomic organizational and structural similarities, the closely related human T-cell lymphotropic virus type-2 (HTLV-2) is considered apathogenic and has been linked with benign lymphoproliferation and mild neurological symptoms in certain infected patients. The silencing of proviral gene expression and maintenance of latency are central for the establishment of persistent infections in vivo. The conserved pX sequences of HTLV-1 and HTLV-2 encode several ancillary factors which have been shown to negatively regulate proviral gene expression, while simultaneously activating host cellular proliferative and pro-survival pathways. In particular, the ORF-II proteins, HTLV-1 p30 II and HTLV-2 p28 II , suppress Tax-dependent transactivation from the viral promoter-whereas p30 II also inhibits PU.1-mediated inflammatory-signaling, differentially augments the expression of p53-regulated metabolic/pro-survival genes, and induces lymphoproliferation which could promote mitotic proviral replication. The ubiquitinated form of the HTLV-1 p13 II protein localizes to nuclear speckles and interferes with recruitment of the p300 coactivator by the viral transactivator Tax. Further, the antisense-encoded HTLV-1 HBZ and HTLV-2 APH-2 proteins and mRNAs negatively regulate Tax-dependent proviral gene expression and activate inflammatory signaling associated with enhanced T-cell lymphoproliferation. This review will summarize our current understanding of the pX latency-maintenance factors of HTLV-1 and HTLV-2 and discuss how these products may contribute to the differences in pathogenicity between the human PTLVs.

Human T cell leukemia virus type 1 (HTLV-1) was the first discovered human retrovirus and the etiologic agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. Shortly after the discovery of HTLV-1, human T-cell leukemia virus type 2 (HTLV-2) was isolated from a patient with hairy cell leukemia. Despite possession of similar structural features to HTLV-1, HTLV-2 has not been definitively associated with lymphoproliferative disease. Since their discovery, studies have been performed with the goal of highlighting the differences between HTLV-1 and HTLV-2. A better understanding of these differences will shed light on the specific pathogenic mechanisms of HTLV-1 and lead to novel therapeutic targets. This review will compare and contrast the two oldest human retroviruses with regards to epidemiology, genomic structure, gene products, and pathobiology.

Introduction: Individuals infected with the human T-cell lymphotropic virus type 1 (HTLV-1) commonly present skin lesions, which may be a warning sign for the diagnosis of infection. This study describes the most prevalent skin manifestations in HTLV carriers attended at the clinic of Núcleo de Medicina Tropical (NMT) of the Universidade Federal do Pará (UFPA) in Belém, Pará, Brazil., Methods: This is a study of a series of cases of patients infected with human T-cell lymphotropic virus types 1 and 2 (HTLV-1/2) treated at NMT UFPA between 1999 and 2016. A descriptive analysis of data was applied., Results: Among 788 surveyed medical records in the service, 15.10% (n = 119) were referred to the dermatology clinic. From the series of cases that presented with skin lesions, 66.39% were female and 33.61% were male, and the average age of this group was 48 years. There was a predominance of patients with noninfectious inflammatory manifestations (64.2%), followed by infectious ones (24.6%), and 1.58% with lymphoproliferative diseases. As for the group of lesions, 45.26% of the erythematous-squamous type were observed, followed by dyschromia (24.21%), and eczematous (14.74%). One patient with a diagnosis of adult T-cell leukemia/lymphoma, another with parapsoriasis, and four with infective dermatitis are highlighted., Conclusion: Skin disorders in the HLTV positive patient are important causes of referral to the dermatologist with etiological and skin lesions groups diversity. In the series of cases studied, lymphoproliferatives diseases and infective dermatitis associated with HTLV-1 were presented as a challenge for the diagnosis and clinical management of these patients., (© 2019 The International Society of Dermatology.)

Background: Human T-lymphotrophic virus (HTLV) types 1 and 2 cause lifelong infection whereby most infected individuals are asymptomatic whilst a minority develop infection-related disease. These latter patients invariably have been found to have high proviral load (PVL). Therefore, infected patients are monitored by determining the proportion of lymphocytes that are infected with HTLV-1/2. An increase in PVL has been shown to represent an increasing risk of developing HTLV-associated diseases. Monitoring of PVL requires a reliable and sensitive method. In this study assays based on droplet digital PCR (ddPCR) were established and evaluated for detection and quantification of HTLV-1/2., Objectives: To develop two parallel assays to detect the tax genes and determine the PVL of HTLV-1 and -2., Study Design: Sixty-seven clinical samples from patients infected with HTLV-1 or HTLV-2 were analysed. The samples had previously been analysed with a qPCR and a comparison between ddPCR and qPCR was performed. The specificity of the assays were determined by analyzing samples from 20 healthy blood donors., Results: The ddPCR was a stable and sensitive method for detection and quantification of HTLV-1 and -2. When comparing the qPCR and ddPCR the correlation was high (Pearsons correlation coefficient 0.96). The variability of the ddPCR was very low with intra-assay coefficient of variation (CV) of 0.97-3.3% (HTLV-1) and 1.7-8.2% (HTLV-2) and inter-assay CV of 1.8-6.1% (HTLV-1) and 1.2-12.9% (HTLV-2)., Conclusions: The ddPCR reliably quantified HTLV DNA in clinical samples and could be a useful tool for monitoring of PVLs in HTLV-infected individuals., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Aims: To assess the prevalence of HTLV-1 and HTLV-2 infections in a cohort of immigrants living in southern Italy., Findings: We screened for antibody to HTLV-1/2 infection 1,498 consecutive immigrants born in endemic areas (sub-Saharan Africa or southern-Asia) by a commercial chemiluminescent microparticle immunoassay. If confirmed in a Western blot assay, which differentiates anti-HTLV-1 from anti-HTLV-2, the positive sera were tested for specific HTLV RNA by a home-made PCR. The immigrants investigated were more frequently males (89.05%), young (median age 26 years), with a low level of education (median schooling 6 years), born in sub-Saharan Africa (79.70%). They had been living in Italy for a median period of 5 months. Only one (0.07%) subject was anti-HTLV-1 -positive/HTLV-1 RNA-negative; he was an asymptomatic 27-year-old male from Nigeria with 6 years' schooling who stated unsafe sexual habits and unsafe injection therapy., Conclusions: The data suggest screening for HTLV1 and HTLV-2 infections all blood donors to Italy from endemic countries at least on their first donation; however, a cost-effectiveness study is needed to clarify this topic., Competing Interests: We declare that author Nicola Coppola has no affiliations to Gilead science company and has no financial competing interests.

Co-infections of hepatitis C virus (HCV) and either human immunodeficiency virus type 1 (HIV-1), human T-cell lymphotropic virus type 1 (HTLV-1) or type 2 (HTLV-2) have been described as having an impact on HCV viremia and subsequent disease progression. HCV load in serum samples from 622 patients (343 males, 279 females; median age 50.8 years) from São Paulo/southeast Brazil was analyzed using the Abbott Real Time HCV assay (Abbott Molecular Inc., IL, USA). Samples were obtained from HCV-monoinfected (n=548), HCV/HIV-1- (n=41), HCV/HTLV-1- (n=16), HCV/HTLV-2- (n=8), HCV/HIV/HTLV-1- (n=4), and HCV/HIV/HTLV-2-co-infected (n=5) patients, and results were compared among the groups and according to sex. The median HCV load in HCV-monoinfected patients was 5.23 log 10 IU/mL and 0.31 log 10 higher in men than in women. Increases in viral load of 0.51 log 10 , 0.54 log 10 , and 1.43 log 10 IU/mL were detected in HCV/HIV-1-, HCV/HTLV-1- and HCV/HIV/HTLV-1-co-infected individuals, respectively, compared with HCV-monoinfected counterparts. In contrast, compared to HCV/HIV co-infected patients, HCV/HTLV-2-co-infected patients had an HCV load of 5.0 log 10 IU/mL, whereas HCV/HIV/HTLV-2-co-infected patients had a median load 0.37 log 10 IU/mL lower. Significant differences in HCV loads were detected, with males and HCV/HIV-1- and HCV/HIV/HTLV-1-co-infected patients presenting the highest values. Conversely, females and HCV/HTLV-2-co-infected patients exhibited lower HCV loads. Overall, HCV viremia is increased in HIV and/or HTLV-1-co-infection and decreased in HTLV-2 co-infection., (Copyright © 2018 Sociedade Brasileira de Infectologia. Published by Elsevier Editora Ltda. All rights reserved.)

Introduction: Human T-lymphotropic virus type 1 and 2 (HTLV-1/2) is endemic in Brazil, but few studies have investigated the seroprevalence of HTLV and its subtypes among blood donors in the capital city Manaus, Amazonas State, Brazil., Aim: To estimate the seroprevalence of HTLV-1/2 and to identify circulating subtypes among blood donors in Manaus., Materials and Methods: Blood donors (2001-2003) were screened for HTLV-1/2 antibodies by ELISA. Positive results were confirmed and subtyped by Western blot assays. Prevalence rates were calculated and compared with demographic data., Results: Among the 87,402 individuals screened, 116 (0.13%) were seropositive for HTLV-1/2. A second sample (76/116) was collected and retested by HTLV-1/2 ELISA, of which only 41/76 were positive. Western blot confirmed HTLV infection in 24/41 retested blood donors [HTLV-1 (n=16), HTLV-2 (n=5) and HTLV-untypable (n=3)]., Discussion: HTLV-1 and HTLV-2 are prevalent among blood donors in Manaus. However, additional studies are needed to comprehend the epidemiology of HTLV-1/2 in Amazonas not only to understand the pathophysiology of the disease providing adequate medical assistance, but also to reduce or block virus transmission.

A known HIV-1-positive intravenous drug user was found to be human T cell lymphoma/leukemia virus-II (HTLV-II) DNA positive by polymerase chain reaction but seronegative in a screening ELISA. He was consistently DNA positive but took 2 years to fully seroconvert. Sequencing of the HTLV-II strain in his cultured T lymphocytes indicated that it is a prototypical type A strain with no major differences in the long terminal repeat DNA sequence, nor major amino acid differences in the Gag, Env, Tax, and Rex proteins. However, a mutation in its pol gene created a stop codon at amino acid 543 of the Pol protein, a region that encodes for the RNase function. This mutation may account for the subject's slow seroconversion.

Background: Retroviruses of human T-lymphotropic viruses (HTLV-1 and HTLV-2) have been demonstrated to be endemic in the north-eastern region of Iran. This study was aimed to determine the HTLV-1 and HTLV-2 prevalence among healthy individuals in Neyshabur City during 2010-2014., Methods: A total of 8054 blood samples were collected from healthy participants in Neyshabur, North-Eastern Iran. The blood samples were screened for the presence of specific antibodies against HTLV-1 and HTLV-2 by using ELISA according to the manufacturer's instructions., Results: The overall seropositivity rate for HTLV-1 and HTLV-2 was found to be 6.55% (528 out of 8054) among participants., Conclusion: Both HTLV-1 and HTLV-2 were demonstrated to be at a high rate in healthy individuals. However, a smaller number of asymptomatic carriers were found in this study, as compared to those identified in previous investigations in the city., Competing Interests: CONFLICT OF INTEREST. None declared.

Introduction: Human T-lymphotropic virus type 1 or 2 (HTLV-1/2) co-infection in patients infected with the human immunodeficiency virus (HIV) can lead to increased morbidity. Because HTLV-1/2 shares a similar transmission route with HIV, HTLV-1/2 infection may be more prevalent in HIV-infected individuals. However, rates of HTLV-1/2 co-infection among HIV-infected individuals have not been studied recently in the United States., Materials and Methods: We conducted a cross-sectional study using serum from 292 HIV-infected subjects from one clinic in Virginia. Serum samples were tested for co-infection with HTLV-1/2 by commercial ELISA; positive results were then confirmed via western blot, which also differentiated between HTLV-1 and -2., Results: Seven (2.4%) of the subjects were co-infected with HTLV-2. One subject (among the seven co-infected with HTLV-2) was co-infected with HTLV-1 (0.3%). The only demographic factor significantly associated with HTLV-2 infection was history of intravenous drug abuse (p=0.002)., Conclusions: While our results are limited to a single city, our low rates of co-infection do not support routine screening for HTLV-1/2 co-infection among HIV-infected individuals in the United States., (Copyright © 2016 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.)

Background: In Europe, human T-lymphotropic virus (HTLV) type 2 mainly occurs among intravenous drug users (IDUs) with prevalence up to 15% and HTLV-1 among general population with prevalence <1%. However, there is no data regarding the prevalence of HTLV-1 or HTLV-2 in Eastern European IDUs population where HIV prevalence is relatively high. We aimed to determine the prevalence and genotypes of HTLV-1/HTLV-2 among IDUs and healthy volunteers in Estonia., Methods: The study included 345 IDUs and 138 healthy volunteers. The presence of HTLV-1/HTLV-2 was determined by nested PCR; positive and negative controls were used in every PCR run., Results: The analysed IDUs resembled the IDUs of HIV epidemic in Estonia: mainly male (79%) with median age of 30years (interquartile range [IQR] 25-34), and prolonged duration of intravenous drug usage (11years; IQR 7-14). The prevalence exposure to blood-borne viral infections was high - 50% were HIV positive, 88% hepatitis C positive, 67% hepatitis B positive. Of IDUs, 64% reported receptive needle sharing in the past and 18% at least once a month during last six months. None of the IDUs carried HTLV-1 but there was a case of HTLV-2 (prevalence 0.3%; 95% CI 0.1-1.6). All healthy volunteers were HTLV-1 and HTLV-2 PCR negative., Conclusion: This is the first study investigating the prevalence of HTLV-1/HTLV-2 among high risk population and healthy volunteers in Eastern European region. Our results suggest that despite other widely spread blood-borne infections (e.g. HIV, HBV, HCV) HTLV-1 and HTLV-2 are rare among IDUs in Estonia., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Short or damaged telomeres have been implicated in degenerative conditions. We hypothesized that analysis of telomere length (TL) in human T-cell lymphotropic virus (HTLV) infection and HTLV-associated neuropathy might provide clues to the etiology of HTLV-associated disease and viral dynamics. A subset of 45 human T-cell lymphotropic virus type 1 (HTLV-1), 45 human T-cell lymphotropic virus type 2 (HTLV-2), and 45 seronegative subjects was selected from the larger HTLV Outcomes Study (HOST) cohort, matched on age, sex and race/ethnicity. Telomere-to-single-copy gene (T/S) ratio (a measure of TL) and HTLV-1 and HTLV-2 proviral loads were measured in peripheral blood mononuclear cells (PBMCs) using quantitative PCR (qPCR). Vibration sensation measured by tuning fork during neurologic examinations performed as part of the HOST study allowed for an assessment of peripheral neuropathy. TL was compared between groups using t-tests, linear and logistic regression. Mean T/S ratio was 1.02 ± 0.16 in HTLV-1, 1.03 ± 0.17 in HTLV-2 and 0.99 ± 0.18 in HTLV seronegative subjects (p = 0.322). TL was not associated with HTLV-1 or -2 proviral load. Shorter TL was significantly associated with impaired vibration sense in the HTLV-2 positive group only. Overall, we found no evidence that telomere length was affected by chronic HTLV-1 and HTLV-2 infection. That TL was only associated with peripheral neuropathy in the HTLV-2-positive group is intriguing, but should be interpreted cautiously. Studies with larger sample size and telomere length measurement in lymphocyte subsets may clarify the relationship between TL and HTLV-infection.

Infection with human T-lymphotropic virus type 1/2 (HTLV-1/2) is a major health problem. HTLV-1/2 infection is endemic in Chile but representative donor prevalence data are lacking. Data on all blood donors in a large network of Chilean blood centers were examined during 2011-2013. Screening of HTLV-1/2 antibodies were measured by enzyme immunoassay (EIA) at all blood banks. Blood samples with anticoagulants from initially reactive blood donors were analyzed by serological confirmation tests (immunofluorescence or recombinant immunoblot) at the HTLV National Reference Laboratory of the Public Health Institute of Chile. Additionally, detection of HTLV-1 and HTLV-2 provirus in peripheral blood mononuclear cells (PBMCs) was performed in all blood donors as confirmatory test. Prevalence rates were calculated. Among 694,016 donors, 706 were seropositive for HTLV-1 (prevalence, 1.02 cases per 1,000; 95% confidence interval [CI], 0.94-1.09), and 97 were seropositive for HTLV-2 (prevalence, 0.14 cases per 1,000; 95%CI, 0.11-0.17). Prevalence of HTLV-1 differed considerably by region, from 0.51 to 1.69 per 1,000. Prevalence of HTLV-2 was similar across the country (0.12-0.16). HTLV-1 prevalence was associated with female sex, older age, and residence in the north of Chile. HTVL-2 prevalence was associated with older age. The HTLV-1 prevalence among Chilean blood donors was relatively high and could be reduced by improving donor recruitment and selection in high prevalence areas. Blood center data may contribute to surveillance for HTLV-1 and HTLV-2 infections., (© 2015 Wiley Periodicals, Inc.)

The human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 are common copathogens among Human Immunodeficiency Virus (HIV)-infected individuals. HTLV-2 may confer a survival benefit among patients with HIV-1/HTLV-2 coinfections, along with lower plasma HIV-1 levels and delayed rates of CD4(+) T-cell decline. These effects have been attributed to the ability of the HTLV-2 viral transactivating Tax2 protein to induce the production of high levels of antiviral CC-chemokines and to downregulate expression of the CCR5 receptor, resulting in impaired entry of HIV-1 into CD4(+) T-cells. This study investigated the innate immunity of coinfected HIV/HTLV individuals by testing the ability of patient PBMCs to produce CC-chemokines in association CCR5 receptor modulation. The cellular proliferative responses of HIV/HTLV coinfected versus HIV monoinfected individuals were also evaluated. Higher levels of MIP-1α, MIP-1β, and RANTES (P < 0.05) were found in HIV-1/HTLV-2 coinfected group compared to HIV-1 monoinfected population. Upregulated levels of RANTES were shown in HIV-1/HTLV-1 after 1 and 3 days of culture (P < 0.05). Lymphocytes from HIV-1/HTLV-2 coinfected individuals showed significant CCR5 downregulation after 1 and 3 days of culture compared to lymphocytes from HIV-1 and uninfected groups (P < 0.05). Lower percentages of CCR5-positive cells were found in HIV-1/HTLV-1 coinfected after 3 days of incubation (P < 0.05). Levels of proliferation were significantly higher in the HIV-1/HTLV-1 group compared to HIV-1 alone (P < 0.05). HTLV-2 and HTLV-1 infections may induce the involvement of innate immunity against HIV-1 via stimulation of CC-chemokines and receptors, potentially modifying CCR5/HIV-1 binding and HIV-1 progression in coinfected individuals., (© 2015 Wiley Periodicals, Inc.)

Introduction: This study confirmed the absence of natural infection with Xenotropic murine leukemia virus-related virus (XMRV) or XMRV-related disease in human populations of the Brazilian Amazon basin. We demonstrated that 803 individuals of both sexes, who were residents of Belem in the Brazilian State of Pará, were not infected with XMRV., Methods: Individuals were divided into 4 subgroups: healthy individuals, individuals infected with human immunodeficiency virus, type 1 (HIV-1), individuals infected with human T-lymphotrophic virus, types 1 or 2 (HTLV-1/2), and individuals with prostate cancer. XMRV infection was investigated by nested PCR to detect the viral gag gene and by quantitative PCR to detect pol., Results: There was no amplification of either gag or pol segments from XRMV in any of the samples examined., Conclusions: This study supports the conclusions of the studies that eventually led to the retraction of the original study reporting the association between XMRV and human diseases.

Human T-lymphotropic virus type 1 (HTLV-1) and type 2 (HTLV-2) both cause lifelong persistent infections, but differ in their clinical outcomes. HTLV-1 infection causes a chronic or acute T-lymphocytic malignancy in up to 5% of infected individuals whereas HTLV-2 has not been unequivocally linked to a T-cell malignancy. Virus-driven clonal proliferation of infected cells both in vitro and in vivo has been demonstrated in HTLV-1 infection. However, T-cell clonality in HTLV-2 infection has not been rigorously characterized. In this study we used a high-throughput approach in conjunction with flow cytometric sorting to identify and quantify HTLV-2-infected T-cell clones in 28 individuals with natural infection. We show that while genome-wide integration site preferences in vivo were similar to those found in HTLV-1 infection, expansion of HTLV-2-infected clones did not demonstrate the same significant association with the genomic environment of the integrated provirus. The proviral load in HTLV-2 is almost confined to CD8+ T-cells and is composed of a small number of often highly expanded clones. The HTLV-2 load correlated significantly with the degree of dispersion of the clone frequency distribution, which was highly stable over ∼8 years. These results suggest that there are significant differences in the selection forces that control the clonal expansion of virus-infected cells in HTLV-1 and HTLV-2 infection. In addition, our data demonstrate that strong virus-driven proliferation per se does not predispose to malignant transformation in oncoretroviral infections.

Background: Numerous studies have analyzed the effects of raltegravir intensification on HIV-1 viral replication in infected individuals receiving suppressive combined antiretroviral treatment (cART). Nevertheless, there are only two studies on the effect of raltegravir in HTLV-1 infection, and none in HTLV-2., Objective: To study the effect of raltegravir on HTLV-2 infection in HIV-1-co-infected individuals., Study Design: This retrospective longitudinal study included four HTLV-2-HIV-1-co-infected individuals who received raltegravir-based cART during 48 weeks and 11 HTLV-2-HIV-1-co-infected individuals under cART without raltegravir during 48 weeks. HTLV-2 proviral load, CD4 and CD8 count and frequency were analyzed., Results: HTLV-2 proviral load significantly increased at week 24 compared to baseline among all the patients who received raltegravir (p=0.003), while no significant increases were found in the control group. No significant variation in either CD8 or CD4 counts was found during the follow up in both groups., Conclusions: Raltegravir induced a transient increment on total HTLV-2 DNA proviral load in HTLV-2/HIV-1-coinfected individuals on suppressive cART after 24 weeks., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: Human T-lymphotropic virus type 1 (HTLV-1) and HTLV-2 are prevalent at low levels among US blood donors, but recent data on their prevalence is lacking. METHODS. Data on all first-time blood donors in a large network of US blood centers were examined during 2000-2009. HTLV-1 and HTLV-2 antibodies were measured by enzyme immunoassay (EIA) with confirmation by immunofluorescence or recombinant immunoblot. Prevalence rates were calculated, and odds ratios were assessed using multivariable logistic regression., Results: Among 2 047 740 first-time donors, 104 were seropositive for HTLV-1 (prevalence, 5.1 cases/per 100 000; 95% confidence interval [CI], 4.1-6.1), and 300 were seropositive for HTLV-2 (prevalence, 14.7 cases/per 100 000; 95% CI, 13.0-16.3). The prevalence was lower than reported in the 1990s but stable from 2000 to 2009. HTLV-1 seropositivity was associated with female sex, older age, and black and Asian race/ethnicity. HTLV-2 seropositivity was associated with female sex, older age, nonwhite race/ethnicity, lower educational level, and residence in the western and southwestern United States., Conclusions: The HTLV-1 and HTLV-2 prevalences among US blood donors has declined since the early 1990s. A higher prevalence of HTLV-2 in the west and southwest may be attributed to endemic foci among Amerindians.

Retroviral RNA encapsidation involves a recognition event between genomic RNA (gRNA) and one or more domains in Gag. In HIV-1, the nucleocapsid (NC) domain is involved in gRNA packaging and displays robust nucleic acid (NA) binding and chaperone functions. In comparison, NC of human T-cell leukemia virus type 1 (HTLV-1), a deltaretrovirus, displays weaker NA binding and chaperone activity. Mutation of conserved charged residues in the deltaretrovirus bovine leukemia virus (BLV) matrix (MA) and NC domains affects virus replication and gRNA packaging efficiency. Based on these observations, we hypothesized that the MA domain may generally contribute to NA binding and genome encapsidation in deltaretroviruses. Here, we examined the interaction between HTLV-2 and HIV-1 MA proteins and various NAs in vitro. HTLV-2 MA displays higher NA binding affinity and better chaperone activity than HIV-1 MA. HTLV-2 MA also binds NAs with higher affinity than HTLV-2 NC and displays more robust chaperone function. Mutation of two basic residues in HTLV-2 MA α-helix II, previously implicated in BLV gRNA packaging, reduces NA binding affinity. HTLV-2 MA binds with high affinity and specificity to RNA derived from the putative packaging signal of HTLV-2 relative to nonspecific NA. Furthermore, an HIV-1 MA triple mutant designed to mimic the basic character of HTLV-2 MA α-helix II dramatically improves binding affinity and chaperone activity of HIV-1 MA in vitro and restores RNA packaging to a ΔNC HIV-1 variant in cell-based assays. Taken together, these results are consistent with a role for deltaretrovirus MA proteins in viral RNA packaging.

We investigated the incidence of human T-cell leukemia virus type I (HTLV-1) infection in a total of 17 regions in four countries, including 13 regions in Japan, as well as Korea (Seoul and Busan), China, and Vietnam, by testing breast milk using a particle agglutination assay (PA) and line immunoassay (LIA). Among 266 samples from Japan, 24 (9.0%) were positive on PA and 3 (1.1%) were positive on LIA. Among 50 samples from Seoul, 2 were positive on PA and 1 was positive on LIA. In contrast, all 50 samples from Busan were negative on both tests, suggesting the maldistribution of HTLV-1 infectants in South Korea. The numbers of positive samples were 2/91 on PA and 1/91 on LIA for China and 1/88 on both PA and LIA for Vietnam. In China, one sample with a high probability of HTLV-2 infection was identified by LIA and synthetic peptide enzyme-linked immunosorbent assay (ELISA). We examined HTLV-1 antibody in breast milk samples using commercially available test kits, suggesting the existence of HTLV-1 carriers in endemic areas in Southeast Asia and an HTLV-2 infectant in China. As a part of human ethno-epidemiological research, these results constitute valuable epidemiological data. Further studies on the sensitivity, specificity, and reliability of assays using antibodies to HTLV-1 and 2 in breast milk will be necessary for large-scale epidemiological surveys of HTLV infection.

Type I interferon (IFN-I) inhibits the replication of different viruses. However, the effect of IFN-I on the human T-lymphotropic virus type 1 (HTLV-1) viral cycle is controversial. Here, we investigated the consequences of IFN-α addition for different steps of HTLV-1 and HTLV-2 infection. We first show that alpha interferon (IFN-α) efficiently impairs HTLV-1 and HTLV-2 de novo infection in a T cell line and in primary lymphocytes. Using pseudotyped viruses expressing HTLV-1 envelope, we then show that cell-free infection is insensitive to IFN-α, demonstrating that the cytokine does not affect the early stages of the viral cycle. In contrast, intracellular levels of Gag, Env, or Tax protein are affected by IFN-α treatment in T cells, primary lymphocytes, or 293T cells transfected with HTLV-1 or HTLV-2 molecular clones, demonstrating that IFN-α acts during the late stages of infection. We show that IFN-α does not affect Tax-mediated transcription and acts at a posttranscriptional level. Using either small interfering RNA (siRNA) directed against PKR or a PKR inhibitor, we demonstrate that PKR, whose expression is induced by interferon, plays a major role in IFN-α-induced HTLV-1/2 inhibition. These results indicate that IFN-α has a strong repressive effect on the HTLV-1 and HTLV-2 viral cycle during de novo infection of cells that are natural targets of the viruses.

Patients with HIV-1 and human T-lymphotropic virus type 2 (HTLV-2) coinfections often exhibit a clinical course similar to that seen in HIV-1-infected individuals who are long-term nonprogressors. These findings have been attributed in part to the ability of HTLV-2 to activate production of antiviral chemokines and to downregulate the CCR5 coreceptor on lymphocytes. To further investigate these observations, we tested the ability of recombinant Tax1 and Tax2 proteins to suppress HIV-1 viral replication in vitro. R5-tropic HIV-1 (NLAD8)-infected peripheral blood mononuclear cells (PBMCs) were treated daily with recombinant Tax1 and Tax2 proteins (dosage range 1-100 pM). Culture supernatants were collected at intervals from days 1 to 22 postinfection and assayed for levels of HIV-1 p24 antigen by ELISA. Treatment of PBMCs with Tax2 protein resulted in a significant reduction in HIV-1 p24 antigen levels (p<0.05) at days 10, 14, and 18 postinfection compared to HIV-1-infected or mock-treated PBMCs. This was preceded by the detection of increased levels of CC-chemokines MIP-1α/CCL3, MIP-1β/CCL4, and RANTES/CCL5 on days 1-7 of infection. Similar, but less robust inhibition was observed in Tax1-treated PBMCs. These results support the contention that Tax1 and Tax2 play a role in generating antiviral responses against HIV-1 in vivo and in vitro.

The human T cell lymphotropic virus type 2 (HTLV-2) is found mainly in Amerindians and in intravenous drug users (IDUs) from urban areas of the United States, Europe, and Latin America. Worldwide, HTLV-2a and HTLV-2b subtypes are the most prevalent. Phylogenetic analysis of HTLV-2 isolates from Brazil showed the HTLV-2a subtype, variant -2c, which spread from Indians to the general population and IDUs. The present study searched for the types of HTLV-2 that predominate among HIV-1-coinfected patients from southern and southeastern Brazil. Molecular characterization of the LTR, env, and tax regions of 38 isolates confirmed the HTLV-2c variant in 37 patients, and one HTLV-2b in a patient from Paraguay. Phylogenetic analysis of sequences showed different clades of HTLV-2 associated with risk factors and geographic region. These clades could represent different routes of virus transmission and/or little diverse evolutionary rates of virus. Taking into account the results obtained in the present study and the lack of the prototypic North American HTLV-2a strain and HTLV-2b subtypes commonly detected among HIV-coinfected individuals worldwide, we could speculate on the introduction of Brazilian HTLV-2 strains in such populations before the introduction of HIV.

Introduction: This study was conducted to determine the current molecular prevalence of human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV), and human T lymphotropic virus-1/2 (HTLV-1/2) circulating among drug abuser inmates incarcerated in prisons located in Central Java, Indonesia., Methodology: Socio-epidemiological data and blood specimens were collected from 375 drug abuser inmates in four prisons. The blood samples were analyzed with serological and molecular testing for HIV, HBV, HCV, HDV, and HTLV-1/2., Results: The seroprevalence of HIV, HBsAg, HCV, HDV, and HTLV-1/2 in drug abuser inmates was 4.8% (18/375), 3.2% (12/375), 34.1% (128/375), 0% (0/375), and 3.7% (14/375), respectively. No co-infections of HIV and HBV were found. Co-infections of HIV/HCV, HIV/HTLV-1/2, HBV/HCV, HBV/HTLV-1/2, and HCV/HTLV-1/2 were prevalent at rates of 4% (15/375), 1.3% (5/375), 1.1% (4/375), 0.3% (1/375), and 2.1% (8/375), respectively. The HIV/HCV co-infection rate was significantly higher in injection drug users (IDUs) compared to non-IDUs. Triple co-infection of HIV/HCV/HTLV-1/2 was found only in three IDUs (0.8%). HIV CRF01&#95;AE was found to be circulating in the inmates. HBV genotype B3 predominated, followed by C1. Subtypes adw and adr were found. HCV genotype 1a predominated among HCV-infected inmates, followed by 1c, 3k, 3a, 4a, and 1b. All HTLV-1 isolates shared 100% homology with HTLV-1 isolated in Japan, while all of the HTLV-2 isolates were subtype 2a., Conclusion: Drug abuser inmates in prisons may offer a unique community to bridge prevention and control of human blood-borne virus infection to the general community.

Background: Human T cell lymphotropic virus type 1 and 2 (HTLV-1/2) causes serious diseases and is endemic in many parts of the world. It is transmitted from mother to child in 15-25% of the cases, primarily through breastfeeding. Proviral load and duration of breastfeeding are thought to play a role in transmission. This study aimed to detect HTLV-seropositive mothers through testing of neonates, to evaluate maternal HTLV proviral load and to measure the rates of transmission blocking when interruption of breastfeeding was implemented., Methods: Neonates were screened for HTLV-1/2 IgG by enzyme immunoassay using the neonatal screening program of Minas Gerais State, Brazil. Breastfeeding interruption was recommended to those whose mothers were confirmed HTLV-positive. Children were tested by polymerase chain reaction at birth and at 12 months of age., Results: Of 55,293 neonates tested, 42 (0.076%) were positive for HTLV-1 or HTLV-2 IgG. All 42 were polymerase chain reaction-negative at birth and 1 of 37 (2.7%) became antibody-positive after 12 months. His mother had delivered him vaginally and was informed of the positive HTLV-1 polymerase chain reaction after 7 days of breastfeeding. The mother's proviral load was 271 copies/10,000 cells, whereas the average is 109.2 copies/10,000 cells (95% confidence interval: 70.56-147.83)., Conclusions: Maternal HTLV-1 proviral load and the route of delivery may have played a role in the transmission observed. Avoidance of breastfeeding was an effective measure to reduce HTLV transmission. In endemic countries, routine prenatal or neonatal screening combined with formula feeding for mothers confirmed HTLV-positive may be an important strategy to prevent future development of illnesses related to HTLV.

Background: Prevalence data on human T-lymphotropic virus types 1 and 2 (HTLV-1/2) in Sweden have not been updated since 1995. The seroprevalence among blood donors at that time was 0.2/10,000. A few years earlier, a high prevalence of HTLV-2 was found in intravenous drug users (IDUs) in Stockholm (3.4%). The objective of this study was to update information on the seroprevalence of HTLV in several study groups., Methods: Serum samples from pregnant women, hepatitis C virus (HCV)-positive individuals, and IDUs in Stockholm were investigated for HTLV-1/2 antibodies. Data from the mandatory HTLV-1/2 screening (2003-2006) of in vitro fertilization (IVF) clients were compiled, as well as data from new blood donors., Results: Eight out of 35,000 IVF patients were positive for anti-HTLV-1/2 (seroprevalence 2.3 per 10,000). Of the anti-HCV-positive individuals (n = 355), 1 sample was HTLV-1-positive (28.2 per 10,000). From 1995 to 2007, 18 HTLV-positive new blood donors were identified out of approximately 550,000 individuals tested (0.3 per 10,000). Thirty-five of 1079 tested IDUs were screening reactive., Conclusions: Since the start of screening in 1994, there has been no increased seroprevalence of HTLV-1/2 among blood donors in Sweden. Seroprevalence among Swedish IVF patients is 10 times higher than among blood donors. This finding is comparable to a 2003 European seroprevalence study of pregnant women in 7 countries. However, the possibility that the IVF group includes individuals with a higher risk of acquiring sexually transmitted infections, including HTLV, than the general population cannot be ruled out.

Background: Human T lymphotropic virus type-1 (HTLV-1) and type 2 (HTLV-2) are closely related human retroviruses, but have unique disease associations. HTLV-1 is the causative agent of an aggressive T-cell leukemia known as adult T-cell leukemia (ATL), HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), and other inflammatory diseases. HTLV-2 infection has not been clearly associated with any disease condition. Although both viruses can transform T cells in vitro, the HTLV-1 provirus is mainly detected in CD4+ T cells whereas HTLV-2 is mainly detected in CD8+ T cells of infected individuals. HTLV-1 and HTLV-2 encode accessory proteins p30 and p28, respectively, which share partial amino acid homology and are required for viral persistence in vivo. The goal of this study was to identify host proteins interacting with p30 and p28 in order to understand their role in pathogenesis., Results: Affinity-tag purification coupled with mass spectrometric (MS) analyses revealed 42 and 22 potential interacting cellular partners of p30 and p28, respectively. Of these, only three cellular proteins, protein arginine methyltransferase 5 (PRMT5), hnRNP K and 60 S ribosomal protein L8 were detected in both p30 and p28 fractions. To validate the proteomic results, four interacting proteins were selected for further analyses using immunoblot assays. In full agreement with the MS analysis two cellular proteins REGγ and NEAF-interacting protein 30 (NIP30) selectively interacted with p30 and not with p28; heterogeneous nuclear ribonucleoprotein H1 (hnRNP H1) bound to p28 and not to p30; and PRMT5 interacted with both p30 and p28. Further studies demonstrated that reduced levels of PRMT5 resulted in decreased HTLV-2 viral gene expression whereas the viral gene expression of HTLV-1 was unchanged., Conclusion: The comparisons of p30 and p28 host protein interaction proteome showed striking differences with some degree of overlap. PRMT5, one of the host proteins that interacted with both p30 and p28 differentially affected HTLV-1 and HTLV-2 viral gene expression suggesting that PRMT5 is involved at different stages of HTLV-1 and HTLV-2 biology. These findings suggest that distinct host protein interaction profiles of p30 and p28 could, in part, be responsible for differences in HTLV-1 and HTLV-2 pathobiology. This study provides new avenues of investigation into mechanisms of viral infection, tropism and persistence.

Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 are closely related but pathogenically distinct human retroviruses. The antisense strand of the HTLV-1 genome encodes HTLV-1 basic leucine zipper (b-ZIP) protein (HBZ), a protein that inhibits Tax-mediated viral transcription, enhances T-cell proliferation, and promotes viral persistence. Recently, an HTLV-2 antisense viral protein (APH-2) was identified. Despite its lack of a typical b-ZIP domain, APH-2, like HBZ, interacts with cyclic AMP response element binding protein (CREB) and downregulates Tax-mediated viral transcription. Here, we provide evidence that the APH-2 C-terminal LXXLL motif is important for CREB binding and Tax repression. In order to investigate the functional role of APH-2 in the HTLV-2-mediated immortalization of primary T lymphocytes in vitro and in HTLV-2 infection in vivo, we generated APH-2 mutant viruses. In cell cultures, the immortalization capacities of APH-2 mutant viruses were indistinguishable from that of wild-type HTLV-2 (wtHTLV-2), indicating that, like HBZ, APH-2 is dispensable for viral infection and cellular transformation. In vivo, rabbits inoculated with either wtHTLV-2 or APH-2 mutant viruses established a persistent infection. However, the APH-2 knockout virus displayed an increased replication rate, as measured by an increased viral antibody response and a higher proviral load. In contrast to HTLV-1 HBZ, we show that APH-2 is dispensable for the establishment of an efficient infection and persistence in a rabbit animal model. Therefore, antisense proteins of HTLV-1 and HTLV-2 have evolved different functions in vivo, and further comparative studies will provide fundamental insights into the distinct pathobiologies of these two viruses.

Human T lymphotropic virus type 1 (HTLV-1) and HTLV-2 are related but pathogenically distinct viruses. HTLV-1 mainly causes adult T cell leukemia, while HTLV-2 is not associated with leukemia. In vitro, HTLV-1 and HTLV-2 predominantly transform CD4(+) and CD8(+) T cells, respectively: the genetic determinant maps to the viral envelope. Herein, we investigate whether this transformation tropism occurs during initial infection or subsequently during the cellular transformation process. Since most individuals are chronically infected at the time of detection, we utilized an established rabbit model to longitudinally measure the early HTLV-1 and HTLV-2 infection and replication kinetics in purified CD4(+) and CD8(+) T cells. HTLV-1 and HTLV-2 were detected in both CD4(+) and CD8(+) T cells within 1 week postinoculation. In HTLV-1-infected rabbit CD4(+) T cells, proviral burden and tax/rex mRNA expression peaked early, and expression levels were directly proportional to each other. The late expression of the antisense transcript (Hbz or Aph-2) correlated directly with a late proviral burden peak in HTLV-1- or HTLV-2-infected rabbit CD8(+) T cells, respectively. This study provides the first in vivo evidence that these viruses do not exhibit cellular preference during initial infection. We further evaluated the transformation tropism of HTLV-1 and HTLV-2 over a 9-week period using in vitro cell growth/immortalization assays. At the early weeks, both HTLV-1 and HTLV-2 showed proportionate growth of CD4(+) and CD8(+) T cells. However, beyond week 5, the predominance of one particular T cell type emerged, supporting the conclusion that transformation tropism is a postinfection event due to selective clonal expansion over time.

We recently discovered the antisense protein of human T-cell leukemia virus (HTLV) type 2 (APH-2), whose messenger RNA is encoded by the antisense strand of the HTLV-2 genome. We quantified proviral load, level of tax, and APH-2 in a series of blood samples obtained from a cohort of HTLV-2 carriers. We determined whether APH-2 promotes cell proliferation. APH-2 was detectable in most samples tested and was correlated with proviral load. APH-2 levels were not correlated with lymphocyte count in vivo, consistent with the inability of APH-2 to promote cell proliferation in vitro. APH-2 does not promote cell proliferation and does not cause lymphocytosis.

Background: No association between the Human T-cell lymphotropic virus (HTLV), an oncogenic virus that alters host immunity, and the Human Papillomavirus (HPV) has previously been reported. Examining the association between these two viruses may permit the identification of a population at increased risk for developing cervical cancer., Methods and Findings: Between July 2010 and February 2011, we conducted a cross-sectional study among indigenous Amazonian Peruvian women from the Shipibo-Konibo ethnic group, a group with endemic HTLV infection. We recruited women between 15 and 39 years of age who were living in the cities of Lima and Ucayali. Our objectives were to determine the association between HTLV and: (i) HPV infection of any type, and (ii) high-risk HPV type infection. Sexually active Shipibo-Konibo women were screened for HTLV-1 and HTLV-2 infections. All HTLV-1 or -2 positive women, along with two community-matched HTLV negative sexually active Shipibo-Konibo controls were later tested for the presence of HPV DNA, conventional cytology, and HIV. We screened 1,253 Shipibo-Konibo women, observing a prevalence of 5.9% (n = 74) for HTLV-1 and 3.8% (n = 47) for HTLV-2 infections. We enrolled 62 (60.8%) HTLV-1 positive women, 40 (39.2%) HTLV-2 positive women, and 205 community-matched HTLV negative controls. HTLV-1 infection was strongly associated with HPV infection of any type (43.6% vs. 29.3%; Prevalence Ratio (PR): 2.10, 95% CI: 1.53-2.87), and with high-risk HPV infection (32.3% vs. 22.4%; PR: 1.93, 95% CI: 1.04-3.59). HTLV-2 was not significantly associated with either of these HPV infections., Conclusions: HTLV-1 infection was associated with HPV infection of any type and with high-risk HPV infection. Future longitudinal studies are needed to evaluate the incidence of high-risk HPV infection as well as the incidence of cervical neoplasia among HTLV-1 positive women.

Human T-cell leukemia viruses types 1 (HTLV-1) and 2 (HTLV-2) produce key transcriptional regulatory gene products, known as Tax1 and Tax2, respectively. Tax1 and Tax2 transactivate multiple host genes involved in cellular immune responses within the cellular microenvironment, including induction of genes encoding expression of CC-chemokines. It is speculated that HTLV Tax proteins may act as immune modulators. In this study, recombinant Tax1 and Tax2 proteins were tested for their effects on the viability of cultured peripheral blood mononuclear cells (PBMCs), and their ability to induce expression of CC-chemokines and to downregulate the level of CCR5 expression in PBMCs. PBMCs obtained from uninfected donors were cultured in a range of Tax1 and Tax2 concentrations (10-100 pM), and supernatant fluids were harvested at multiple time points for quantitative determinations of MIP-1α/CCL3, MIP-1β/CCL4, and RANTES/CCL5. Treatment of PBMCs with Tax1 and Tax2 proteins (100 pM) resulted in a significant increase in viability over a 7-d period compared to controls (p<0.01). Both Tax1 and Tax2 induced high levels of all three CC-chemokines over the dosing range compared to mock-treated controls (p<0.05). The gated population of lymphocytes treated with Tax2, as well as lymphocytes from HTLV-2-infected donors, showed a significantly lower percentage of CCR5-positive cells compared to those of uninfected donors and from mock-treated lymphocytes, respectively (p<0.05). These results suggest that Tax1 and Tax2 could promote innate immunity in the extracellular environment during HTLV-1 and HTLV-2 infections via CC-chemokine ligands and receptors.

Human T-lymphotropic virus (HTLV) infection is rare in the United Kingdom (UK) and few studies are available worldwide. Following introduction of blood donation testing in 2002, a cohort of individuals could be identified and prospectively recruited to describe progression and onset of disease. Here we describe baseline characteristics of participants, and evaluate recruitment into the UK HTLV National Register over the first six years, from July 2003 to June 2009. A multicentre cohort study recruited participants from the UK blood services (recipients and donors) and specialist HTLV clinics. Almost half of the 148 participants recruited were blood donors, nine were blood transfusion recipients, 40 contacts and 29 clinic attendees (nine asymptomatic and 20 symptomatic). Most participants were HTLV-1 positive (n=115); 11 had HTLV-2 and 22 were HTLV-negative. Baseline self-completion questionnaires were received for 83%. The most commonly reported condition was a past operation/serious illness (69%). Twenty-six participants reported four or more possible signs/symptoms of HTLV-1-associated myelopathy/tropical spastic paraparesis. Recruitment into a study of a rare, long-term infection is challenging. This cohort will enable descriptions of HTLV-associated disease progression amongst people recruited from varying sources; it is the first prospective study of its kind in Europe.

Background: Routine diagnosis of Human T Lymphotropic virus (HTLV) infection is primarily serologically based; however the proportion of unresolved and indeterminate Western blot results range from 0.02% to 50% in endemic areas., Objectives: To validate a sensitive in-house quantitative multiplex real-time assay (mqRT-PCR), capable of detecting and quantifying HTLV-1 and HTLV-2, and use it to differentiate unresolved serological profiles, and monitor infection in HTLV-1 infected patients., Study Design: The mqRT-PCR was designed as a single-tube assay. Quantitative results were reported as copy number of HTLV provirus per 10(6) cells and the numbers of cells were calculated based on the quantitative result for albumin, of which there are 2 copies/cell. Assay standards were amplified from HTLV-1 infected MT-2 cells and HTLV-2 transfected CEM cells. Blood samples were obtained from HTLV seropositive former blood donors., Results: The mqRT-PCR assay was efficient (98.8-101.2%), reproducible (coefficient of variance<5%) and sensitive to 1 copy for HTLV-1, HTLV-2 and Albumin. The assay resolved the infection profile in 16/17 patients, with undetermined subtype, all of which were reassigned as HTLV-1 infections. In addition, the average PVL detected in patients suffering from HTLV-1 associated HAM/TSP (n=23, 13,450 copies/10(6) cells) was significantly higher than those detected in asymptomatic carriers (n=21, 6665 copies/10(6) cells)., Conclusions: We propose a new testing algorithm for the laboratory diagnosis of HTLV infection, which includes HTLV specific mqRT-PCR for resolving HTLV serological results. Furthermore, quantitation of PVL load by real-time PCR may be useful in assessing the link between infection and disease, and in monitoring patients undergoing therapy., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Human T-lymphotropic virus type I (HTLV-I) infects an estimated 15-20 million persons worldwide. A number of diseases have been associated with the virus including adult T-cell leukemia (ATL), HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP), HTLV-I uveitis, and HTLV-I-associated infective dermatitis. Once it was shown that there is an increased risk for developing HAM/TSP associated with blood transfusion, screening for HTLV-1 among blood banks was implemented in Japan, United States, France, and the Netherlands. This process includes detection by an enzyme immunoassay (EIA) followed by a confirmatory Western blot (WB) in which recombinant proteins specific for HTLV-I Env glycoproteins are incorporated into WB strips. HTLV-I seropositive results are defined by the presence of antibodies against either gp46 or gp62/68 (both Env protein bands) and either p19, p24, or p53 (one of the gag bands). HTLV-II seropositivity is confirmed by the presence of rgp46-II. However, numerous cases have been documented in which serum samples are reactive by EIA, but an incomplete banding pattern is displayed by subsequent confirmatory WB. Although the significance of these HTLV-I/II seroindeterminates is unclear, it may suggest a much higher incidence of exposure to HTLV-I/II than previously estimated.

Background: Universal HTLV antenatal screening is currently not mandatory in European countries. However, the large number of immigrants coming from HTLV-I endemic areas might force to change this recommendation in the near future., Objectives: To determine the prevalence of HTLV infections in immigrant pregnant women attended in a general Hospital in the Mediterranean coast of Spain., Study Design: From February 2006 to December 2009, a cross-sectional study was carried out on all immigrant pregnant women attended at a reference obstetric unit in Elche, Spain. An enzyme immunoassay (EIA) was used for testing HTLV-I/II antibodies in serum, being reactive samples further confirmed by Western blot., Results: A total of 1439 immigrant pregnant women were examined. Overall, 520 (36.1%) came from Central and South America and 90 (6.2%) from Sub-Saharan Africa, where HTLV infection is endemic. Three samples were EIA-seroreactive for HTLV-1/2. One of them was a woman infected with HTLV-I coming from Brazil and the other two were women infected with HTLV-II coming from Bolivia and Colombia, respectively. Thus, the overall HTLV seroprevalence in the study population was 2.1 per 1000 (95% CI: 0.5-6.6/1000), although it reached to 0.58% in the subset of women from Central and South America., Conclusions: HTLV antenatal screening should be considered in pregnant women coming from Central and South America, in whom the prevalence of infection is relatively high and avoidance of breastfeeding may effectively prevent vertical HTLV transmission., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Human T-lymphotropic viruses type 1 (HTLV-1) and type 2 (HTLV-2) present very similar genomic structures but HTLV-1 is more pathogenic than HTLV-2. Is this difference due to their transactivating Tax proteins, Tax-1 and Tax-2, which are responsible for viral and cellular gene activation? Do Tax-1 and Tax-2 differ in their cellular localization and in their interaction pattern with cellular factors? In this review, we summarize Tax-1 and Tax-2 structural and phenotypic properties, their interaction with factors involved in signal transduction and their localization-related behavior within the cell. Special attention will be given to the distinctions between Tax-1 and Tax-2 that likely play an important role in their transactivation activity.

Human T cell lymphotropic virus type 2 (HTLV-2) infection is endemic in the American Indian population and Pygmy tribes in Africa. Nevertheless, HTLV-2 infection has been predominantly detected in U.S. and European injecting drug users (IDU). Noteworthy is that the HTLV-2a subtype is the main circulating variant in North America and Eastern Europe whereas the HTLV-2b subtype is mainly found in Western Europe, particularly in Italy and Spain where coinfection with HIV-1 is frequent. Twelve Spanish subjects infected with HTLV-2 were recruited for the study. All of them were IDUs coinfected with HIV-1. Molecular epidemiology was done by sequencing the LTR, env, and tax regions and by generating phylogenetic trees. The present study showed that all the sequences belonged to the HTLV-2b subtype and were closely related to other Spanish and Portuguese reported sequences, clearly differentiated from those belonging to the HTLV-2a subtype from Eastern Europe. Therefore, infection with HTLV-2b remains prevalent in Spain based on previous studies.

Human T-cell lymphotropic virus type 1 and 2 (HTLV-1/2) are oncogenic retroviruses linked etiologically to human diseases. In Chile, these viruses have been studied in ethnic populations, or patients diagnosed clinically with HTLV-1 associated myelopathy/tropical spastic paraparesis, but have not been studied in patients with malignant hematological diseases. The aim of this study was to determine the seroprevalence and viral prevalence of HTLV-1/2 among patients with malignant hematological diseases. Eighty-eight patients with malignant hematological diseases were tested by enzyme-linked immunosorbent assay (ELISA) for IgG anti-HTLV-1/2 and nested-PCR for the tax gene. The seroprevalence by ELISA was 3.4% and the viral prevalence by nested-PCR tax was 18.2%. HTLV-1 was found in 17% and HTLV-2 in 1% of the patients tested. HTLV-1/2 was found in 17.4% of patients with non-Hodgkin's lymphomas, 28.6% of patients with Hodgkin's lymphomas, 80% of patients with chronic lymphocytic leukemia, 11.4% of patients with acute lymphoblastic leukemia, and 22.2% of patients with acute myeloid leukemia. A high prevalence of HTLV-1/2 was found in patients with malignant hematological diseases. A high proportion of patients were seronegative to HTLV-1/2 infection, similar to other HTLV-1/2 associated disorders. Because 50% of patients positive for HTLV-1/2 were below 30 years old, it is suggested that vertical transmission could have played an important role in these patients., (Copyright © 2011 Wiley-Liss, Inc.)

In Brazil, human T-lymphotropic virus type 2 (HTLV-2) is endemic in Amerindians and epidemic in intravenous drug users (IDUs). The long terminal repeat (LTR) is the most divergent genomic region of HTLV-2, therefore useful to characterize subtypes. Nucleotide sequence and restriction fragment length polymorphism (RFLP) analysis of LTR genomic segments of fourteen HTLV-2 strains isolated from HIV-infected patients of Londrina, Southern Brazil, were carried out. Molecular analysis disclosed that all HTLV-2 strains belonged to 2a subtype, and RFLP detected the presence of the a4, a5, and a6 subgroups according to Switzer's nomenclature. RFLP correlated with nucleotide sequence, and phylogenetic analysis clustered HTLV-2 sequences of IDUs into subgroups a5 and a6. HTLV-2 sequences from individuals of sexual risk factor clustered into the a4 subgroup. These results extend the knowledge of the genetic diversity of HTLV-2 circulating in Brazil and provide insights into HTLV-2 transmission and virus movement in this geographic area.