49 results found
Kiik H, Ramanayake S, Miura M, et al., 2022, Time-course of host cell transcription during the HTLV-1 transcriptional burst, PLoS Pathogens, Vol: 18, ISSN: 1553-7366
The human T-cell leukemia virus type 1 (HTLV-1) transactivator protein Tax has pleiotropic functions in the host cell affecting cell-cycle regulation, DNA damage response pathways and apoptosis. These actions of Tax have been implicated in the persistence and pathogenesis of HTLV-1-infected cells. It is now known that tax expression occurs in transcriptional bursts of the proviral plus-strand, but the effects of the burst on host transcription are not fully understood. We carried out RNA sequencing of two naturally-infected T-cell clones transduced with a Tax-responsive Timer protein, which undergoes a time-dependent shift in fluorescence emission, to study transcriptional changes during successive phases of the HTLV-1 plus-strand burst. We found that the transcriptional regulation of genes involved in the NF-κB pathway, cell-cycle regulation, DNA damage response and apoptosis inhibition were immediate effects accompanying the plus-strand burst, and are limited to the duration of the burst. The results distinguish between the immediate and delayed effects of HTLV-1 reactivation on host transcription, and between clone-specific effects and those observed in both clones. The major transcriptional changes in the infected host T-cells observed here, including NF-κB, are transient, suggesting that these pathways are not persistently activated at high levels in HTLV-1-infected cells. The two clones diverged strongly in their expression of genes regulating the cell cycle. Up-regulation of senescence markers was a delayed effect of the proviral plus-strand burst and the up-regulation of some pro-apoptotic genes outlasted the burst. We found that activation of the aryl hydrocarbon receptor (AhR) pathway enhanced and prolonged the proviral burst, but did not increase the rate of reactivation. Our results also suggest that sustained plus-strand expression is detrimental to the survival of infected cells.
Melamed A, Fitzgerald T, Wang Y, et al., 2022, Selective clonal persistence of human retroviruses in vivo: radial chromatin organization, integration site and host transcription, Science Advances, Vol: 8, ISSN: 2375-2548
The human retroviruses HTLV-1 and HIV-1 persist in vivo as a reservoir of latently infected T-cell clones. It is poorly understood what determines which clones survive in the reservoir. We compared >160,000 HTLV-1 integration sites (>40,000 HIV-1 sites) from T-cells isolated ex vivo from naturally-infected subjects with >230,000 HTLV-1 integration sites (>65,000 HIV-1 sites) from in vitro infection, to identify genomic features that determineselective clonal survival. Three statistically independent factors together explained >40% of the observed variance in HTLV-1 clonal survival in vivo: the radial intranuclear position of the provirus, its genomic distance from the centromere, and the intensity of local host genome transcription. The radial intranuclear position of the provirus and its distance from the centromere also explained ~7% of clonal persistence of HIV-1 in vivo. Selection for theintranuclear and intrachromosomal location of the provirus, and host transcription intensity, favours clonal persistence of human retroviruses in vivo.
Katsuya H, Cook LBM, Rowan AG, et al., 2022, Clonality of HIV-1 and HTLV-1 infected cells in naturally coinfected individuals, Journal of Infectious Diseases, Vol: 225, Pages: 317-326, ISSN: 0022-1899
BACKGROUND: Coinfection with HIV-1 and HTLV-1 diminishes the value of the CD4 + T-cell count in diagnosing AIDS, and increases the rate of HTLV-1-associated myelopathy. It remains elusive how HIV-1/HTLV-1 coinfection is related to such clinical characteristics. Here, we investigated the mutual effect of HIV-1/HTLV-1 coinfection on their integration sites (ISs) and the clonal expansion. METHODS: We extracted DNA from longitudinal peripheral blood samples from 7 HIV-1/HTLV-1 coinfected individuals, and from 12 HIV-1 and 13 HTLV-1 mono-infected individuals. The proviral loads (PVL) were quantified using real-time PCR. Viral ISs and clonality were quantified by ligation-mediated PCR followed by high-throughput sequencing. RESULTS: The PVL of both HIV-1 and HTLV-1 in coinfected individuals was significantly higher than that of the respective virus in mono-infected individuals. The degree of oligoclonality of both HIV-1- and HTLV-1-infected cells in co-infected individuals was also greater than that in mono-infected subjects. The ISs of HIV-1 in cases of coinfection were more frequently located in intergenic regions and transcriptionally silent regions, compared with HIV-1 mono-infected individuals. CONCLUSION: HIV-1/HTLV-1 coinfection makes an impact on the distribution of viral ISs and the clonality of virus-infected cells and thus may alter the risks of both HTLV-1- and HIV-1-associated disease.
Melamed A, Fitzgerald TW, Wang Y, et al., 2021, Selective clonal persistence of human retroviruses in vivo: radial chromatin organization, integration site and host transcription
<jats:title>Abstract</jats:title><jats:p>The human retroviruses HTLV-1 and HIV-1 persist in vivo, despite the host immune response and antiretroviral therapy, as a reservoir of latently infected T-cell clones. It is poorly understood what determines which clones survive in the reservoir and which are lost. We compared >160,000 HTLV-1 integration sites from T-cells isolated ex vivo from naturally-infected subjects with >230,000 integration sites from in vitro infection, to identify the genomic features that determine selective clonal survival. Three factors explained >40% of the observed variance in clone survival of HTLV-1 in vivo: the radial intranuclear position of the provirus, its absolute genomic distance from the centromere, and the intensity of host genome transcription flanking the provirus. The radial intranuclear position of the provirus and its distance from the centromere also explained ~7% of clonal persistence of HIV-1 in vivo. Selection for transcriptionally repressive nuclear compartments favours clonal persistence of human retroviruses in vivo.</jats:p>
Izaki M, Yasunaga J-I, Nosaka K, et al., 2021, In vivo dynamics and adaptation of HTLV-1-infected clones under different clinical conditions, PLoS Pathogens, Vol: 17, ISSN: 1553-7366
Human T-cell leukemia virus type 1 (HTLV-1) spreads through cell contact. Therefore, this virus persists and propagates within the host by two routes: clonal proliferation of infected cells and de novo infection. The proliferation is influenced by the host immune responses and expression of viral genes. However, the detailed mechanisms that control clonal expansion of infected cells remain to be elucidated. In this study, we show that newly infected clones were strongly suppressed, and then stable clones were selected, in a patient who was infected by live liver transplantation from a seropositive donor. Conversely, most HTLV-1+ clones persisted in patients who received hematopoietic stem cell transplantation from seropositive donors. To clarify the role of cell-mediated immunity in this clonal selection, we suppressed CD8+ or CD16+ cells in simian T-cell leukemia virus type 1 (STLV-1)-infected Japanese macaques. Decreasing CD8+ T cells had marginal effects on proviral load (PVL). However, the clonality of infected cells changed after depletion of CD8+ T cells. Consistent with this, PVL at 24 hours in vitro culture increased, suggesting that infected cells with higher proliferative ability increased. Analyses of provirus in a patient who received Tax-peptide pulsed dendritic cells indicate that enhanced anti-Tax immunity did not result in a decreased PVL although it inhibited recurrence of ATL. We postulate that in vivo selection, due to the immune response, cytopathic effects of HTLV-1 and intrinsic attributes of infected cells, results in the emergence of clones of HTLV-1-infected T cells that proliferate with minimized HTLV-1 antigen expression.
Rowan AG, Dillon R, Witkover A, et al., 2020, Evolution of retrovirus-infected premalignant T-cell clones prior to Adult T-cell leukemia/lymphoma diagnosis, Blood, Vol: 135, Pages: 2023-2032, ISSN: 0006-4971
Adult T cell leukemia/lymphoma (ATL) is an aggressive hematological malignancy caused by Human T-cell leukemia virus type-1 (HTLV-1). ATL is preceded by decades of chronic HTLV-1 infection, and the tumors carry both somatic mutations and proviral DNA integrated into the tumor genome. In order to gain insight into the oncogenic process, we used targeted sequencing to track the evolution of the malignant clone in six individuals, 2-10 years before the diagnosis of ATL. Clones of premalignant HTLV-1-infected cells bearing known driver mutations were detected in the blood up to 10 years before individuals developed acute and lymphoma subtype ATL. Six months before diagnosis, the total number and variant allele fraction of mutations increased in the blood. Peripheral blood mononuclear cells from premalignant cases (1 year pre-diagnosis) had significantly higher mutational burden in genes frequently mutated in ATL than did high risk, age-matched HTLV-1-carriers who remained ATL-free after a median of 10 years of follow up. These data show that HTLV-1-infected T cell clones carrying key oncogenic driver mutations can be detected in cases of ATL years before the onset of symptoms. Early detection of such mutations may enable earlier and more effective intervention to prevent the development of ATL.
Cook L, Demontis MA, Sagawe S, et al., 2019, Molecular remissions are observed in chronic adult T cell leukemia/lymphoma in patients treated with mogamulizumab, Haematologica, Vol: 104, Pages: e566-e569, ISSN: 0390-6078
Cook L, Demontis MA, Sagawe S, et al., 2019, Molecular remissions are observed in chronic adult T-cell leukaemia/lymphoma in patients treated with mogamulizumab, BRITISH JOURNAL OF HAEMATOLOGY, Vol: 185, Pages: 172-173, ISSN: 0007-1048
Turpin J, Yurick D, Khoury G, et al., 2019, Impact of Hepatitis B virus coinfection on human T-lymphotropic virus type 1 clonality in an indigenous population of central Australia, Journal of Infectious Diseases, Vol: 219, Pages: 562-567, ISSN: 0022-1899
The prevalence of human T-cell lymphotropic virus type 1 (HTLV-1) and hepatitis B virus (HBV) coinfection is high in certain Indigenous Australian populations, but its impact on HTLV-1 has not been described. We compared 2 groups of Indigenous adults infected with HTLV-1, either alone or coinfected with HBV. The 2 groups had a similar HTLV-1 proviral load, but there was a significant increase in clonal expansion of HTLV-1–infected lymphocytes in coinfected asymptomatic individuals. The degree of clonal expansion was correlated with the titer of HBV surface antigen. We conclude that HTLV-1/HBV coinfection may predispose to HTLV-1–associated malignant disease.
Bangham CRM, Melamed A, Yaguchi H, et al., 2018, The human leukemia virus HTLV-1 alters the structure and transcription of host chromatin in cis, eLife, Vol: 7, Pages: 1-20, ISSN: 2050-084X
Chromatin looping controls gene expression by regulating promoter-enhancer contacts, the spread of epigenetic modifications, and the segregation of the genome into transcriptionally active and inactive compartments. We studied the impact on the structure and expression of host chromatin by the human retrovirus HTLV-1. We show that HTLV-1 disrupts host chromatin structure by forming loops between the provirus and the host genome; certain loops depend on the critical chromatin architectural protein CTCF, which we recently discovered binds to the HTLV-1 provirus. We show that the provirus causes two distinct patterns of abnormal transcription of the host genome in cis: bidirectional transcription in the host genome immediately flanking the provirus, and clone-specific transcription in cis at non-contiguous loci up to >300 kb from the integration site. We conclude that HTLV-1 causes insertional mutagenesis up to the megabase range in the host genome in >104 persistently-maintained HTLV-1+ T-cell clones in vivo.
Satou Y, Katsuya H, Fukuda A, et al., 2018, Dynamics and mechanisms of clonal expansion of HIV-1-infected cells in a humanized mouse model (vol 7, 6913, 2017), SCIENTIFIC REPORTS, Vol: 8, ISSN: 2045-2322
Melamed A, Yaguchi H, Miura M, et al., 2018, The human leukemia virus HTLV-1 alters the structure and transcription of host chromatin <i>in cis</i>
<jats:title>Abstract</jats:title><jats:p>Chromatin looping controls gene expression by regulating promoter-enhancer contacts, the spread of epigenetic modifications, and the segregation of the genome into transcriptionally active and inactive compartments. We studied the impact on the structure and expression of host chromatin by the human retrovirus HTLV-1. We show that HTLV-1 disrupts host chromatin structure by forming loops between the provirus and the host genome; certain loops depend on the critical chromatin architectural protein CTCF, which we recently showed binds to the HTLV-1 provirus. Finally, we show that the provirus causes two distinct patterns of abnormal transcription of the host genome <jats:italic>in cis</jats:italic>: bidirectional transcription in the host genome immediately flanking the provirus, and clone-specific transcription <jats:italic>in cis</jats:italic> at non-contiguous loci up to >300 kb from the integration site. We conclude that HTLV-1 causes insertional mutagenesis up to the megabase range in the host genome in >10<jats:sup>4</jats:sup> persistently-maintained HTLV-1<jats:sup>+</jats:sup> T-cell clones in vivo.</jats:p>
Furuta R, Yasunaga J-I, Miura M, et al., 2017, Human T-cell leukemia virus type 1 infects multiple lineage hematopoietic cells in vivo., PLoS Pathogens, Vol: 13, ISSN: 1553-7366
Human T-cell leukemia virus type 1 (HTLV-1) infects mainly CD4+CCR4+ effector/memory T cells in vivo. However, it remains unknown whether HTLV-1 preferentially infects these T cells or this virus converts infected precursor cells to specialized T cells. Expression of viral genes in vivo is critical to study viral replication and proliferation of infected cells. Therefore, we first analyzed viral gene expression in non-human primates naturally infected with simian T-cell leukemia virus type 1 (STLV-1), whose virological attributes closely resemble those of HTLV-1. Although the tax transcript was detected only in certain tissues, Tax expression was much higher in the bone marrow, indicating the possibility of de novo infection. Furthermore, Tax expression of non-T cells was suspected in bone marrow. These data suggest that HTLV-1 infects hematopoietic cells in the bone marrow. To explore the possibility that HTLV-1 infects hematopoietic stem cells (HSCs), we analyzed integration sites of HTLV-1 provirus in various lineages of hematopoietic cells in patients with HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) and a HTLV-1 carrier using the high-throughput sequencing method. Identical integration sites were detected in neutrophils, monocytes, B cells, CD8+ T cells and CD4+ T cells, indicating that HTLV-1 infects HSCs in vivo. We also detected Tax protein in myeloperoxidase positive neutrophils. Furthermore, dendritic cells differentiated from HTLV-1 infected monocytes caused de novo infection to T cells, indicating that infected monocytes are implicated in viral spreading in vivo. Certain integration sites were re-detected in neutrophils from HAM/TSP patients at different time points, indicating that infected HSCs persist and differentiate in vivo. This study demonstrates that HTLV-1 infects HSCs, and infected stem cells differentiate into diverse cell lineages. These data indicate that infection of HSCs can contribute to the persistence and spread
Cook LB, Rowan A, Demontis M, et al., 2017, Long-term clinical remission maintained after cessation of zidovudine and interferon-α therapy in chronic adult T-cell leukemia/lymphoma, International Journal of Hematology, Vol: 107, Pages: 378-382, ISSN: 0925-5710
Globally, > 5–10 million people are estimated to be infected with Human T-lymphotropic virus type 1 (HTLV-1), of whom ~ 5% develop adult T-cell leukemia/lymphoma (ATL). Despite advances in chemotherapy, overall survival (OS) has not improved in the 35 years since HTLV-1 was first described. In Europe/USA, combination treatment with zidovudine and interferon-α (ZDV/IFN-α) has substantially changed the management of patients with the leukemic subtypes of ATL (acute or unfavorable chronic ATL) and is under clinical trial evaluation in Japan. However, there is only a single published report of long-term clinical remission on discontinuing ZDV/IFN-α therapy and the optimal duration of treatment is unknown. Anecdotal cases where therapy is discontinued due to side effects or compliance have been associated with rapid disease relapse, and it has been widely accepted that the majority of patients will require life-long therapy. The development of molecular methods to quantify minimal residual disease is essential to potentially guide therapy for individual patients. Here, for the first time, we report molecular evidence that supports long-term clinical remission in a patient who was previously treated with ZDV/IFN-α for 5 years, and who has now been off all therapy for over 6 years.
Human T-lymphotropic virus type-1 (HTLV-1) is the causative agent of adult T-cell leukaemia/lymphoma (ATL), an aggressive CD4+ T-cell malignancy. The mechanisms of leukaemogenesis in ATL are incompletely understood. Insertional mutagenesis has not previously been thought to contribute to the pathogenesis of ATL. However, the recent discovery that HTLV-1 binds the key chromatin architectural protein CTCF raises the hypothesis that HTLV-1 deregulates host gene expression by causing abnormal chromatin looping, bringing the strong HTLV-1 promoter-enhancer near to host genes that lie up to 2Mb from the integrated provirus. Here we review current opinion on the mechanisms of oncogenesis in ATL, with particular emphasis on the local and distant impact of HTLV-1 on the structure and expression of the host genome.
Satou Y, Katsuya H, Fukuda A, et al., 2017, Dynamics and mechanisms of clonal expansion of HIV-1-infected cells in a humanized mouse model., Scientific Reports, Vol: 7, ISSN: 2045-2322
Combination anti-retroviral therapy (cART) has drastically improved the clinical outcome of HIV-1 infection. Nonetheless, despite effective cART, HIV-1 persists indefinitely in infected individuals. Clonal expansion of HIV-1-infected cells in peripheral blood has been reported recently. cART is effective in stopping the retroviral replication cycle, but not in inhibiting clonal expansion of the infected host cells. Thus, the proliferation of HIV-1-infected cells may play a role in viral persistence, but little is known about the kinetics of the generation, the tissue distribution or the underlying mechanism of clonal expansion in vivo. Here we analyzed the clonality of HIV-1-infected cells using high-throughput integration site analysis in a hematopoietic stem cell-transplanted humanized mouse model. Clonally expanded, HIV-1-infected cells were detectable at two weeks post infection, their abundance increased with time, and certain clones were present in multiple organs. Expansion of HIV-1-infected clones was significantly more frequent when the provirus was integrated near host genes in specific gene ontological classes, including cell activation and chromatin regulation. These results identify potential drivers of clonal expansion of HIV-1-infected cells in vivo.
Zhyvoloup A, Melamed A, Anderson I, et al., 2017, Digoxin reveals a functional connection between HIV-1 integration preference and T-cell activation, PLOS PATHOGENS, Vol: 13, ISSN: 1553-7366
HIV-1 integrates more frequently into transcribed genes, however the biological significance of HIV-1 integration targeting has remained elusive. Using a selective high-throughput chemical screen, we discovered that the cardiac glycoside digoxin inhibits wild-type HIV-1 infection more potently than HIV-1 bearing a single point mutation (N74D) in the capsid protein. We confirmed that digoxin repressed viral gene expression by targeting the cellular Na+/K+ ATPase, but this did not explain its selectivity. Parallel RNAseq and integration mapping in infected cells demonstrated that digoxin inhibited expression of genes involved in T-cell activation and cell metabolism. Analysis of >400,000 unique integration sites showed that WT virus integrated more frequently than N74D mutant within or near genes susceptible to repression by digoxin and involved in T-cell activation and cell metabolism. Two main gene networks down-regulated by the drug were CD40L and CD38. Blocking CD40L by neutralizing antibodies selectively inhibited WT virus infection, phenocopying digoxin. Thus the selectivity of digoxin depends on a combination of integration targeting and repression of specific gene networks. The drug unmasked a functional connection between HIV-1 integration and T-cell activation. Our results suggest that HIV-1 evolved integration site selection to couple its early gene expression with the status of target CD4+ T-cells, which may affect latency and viral reactivation.
Bangham CRM, Gillet N, Melamed A, 2017, High-throughput mapping and clonal quantification of retroviral integration sites, Methods in Molecular Biology
Turpin J, Alais S, Marcais A, et al., 2016, Whole body clonality analysis in an aggressive STLV-1 associated leukemia (ATLL) reveals an unexpected clonal complexity, CANCER LETTERS, Vol: 389, Pages: 78-85, ISSN: 0304-3835
HTLV-1 causes Adult T cell Leukemia/Lymphoma (ATLL) in humans. We describe an ATL-like disease in a 9 year-old female baboon naturally infected with STLV-1 (the simian counterpart of HTLV-1), with a lymphocyte count over 1010/L, lymphocytes with abnormal nuclear morphology, and pulmonary and skin lesions. The animal was treated with a combination of AZT and alpha interferon. Proviral load (PVL) was measured every week. Because the disease continued to progress, the animal was euthanized. Abnormal infiltrates of CD3+CD25+ lymphocytes and Tax-positive cells were found by histological analyses in both lymphoid and non-lymphoid organs. PVL was measured and clonal diversity was assessed by LM-PCR (Ligation-Mediated Polymerase Chain Reaction) and high throughput sequencing, in blood during treatment and in 14 different organs. The highest PVL was found in lymph nodes, spleen and lungs. One major clone and a number of intermediate abundance clones were present in blood throughout the course of treatment, and in organs. These results represent the first multi-organ clonality study in ATLL. We demonstrate a previously undescribed clonal complexity in ATLL. Our data reinforce the usefulness of natural STLV-1 infection as a model of ATLL.
Yasunaga J-I, Furuta R, Miura M, et al., 2016, Hematopoietic Stem Cell Infected with HTLV-1 Functions As a Viral Reservoir In Vivo, 58th Annual Meeting and Exposition of the American-Society-of-Hematology (ASH), Publisher: AMER SOC HEMATOLOGY, ISSN: 0006-4971
Rowan A, Witkover A, Melamed A, et al., 2016, T cell receptor Vβ staining identifies the malignant clone in adult T cell leukemia and reveals killing of leukemia cells by autologous CD8+ T cells, Plos Pathogens, Vol: 12, ISSN: 1553-7374
There is growing evidence that CD8+ cytotoxic T lymphocyte (CTL) responses can contribute to long-term remission of many malignancies. The etiological agent of adult T-cell leukemia/lymphoma (ATL), human T lymphotropic virus type-1 (HTLV-1), contains highly immunogenic CTL epitopes, but ATL patients typically have low frequencies of cytokine-producing HTLV-1-specific CD8+ cells in the circulation. It remains unclear whether patients with ATL possess CTLs that can kill the malignant HTLV-1 infected clone. Here we used flow cytometric staining of TCRVβ and cell adhesion molecule-1 (CADM1) to identify monoclonal populations of HTLV-1-infected T cells in the peripheral blood of patients with ATL. Thus, we quantified the rate of CD8+-mediated killing of the putative malignant clone in ex vivo blood samples. We observed that CD8+ cells from ATL patients were unable to lyse autologous ATL clones when tested directly ex vivo. However, short in vitro culture restored the ability of CD8+ cells to kill ex vivo ATL clones in some donors. The capacity of CD8+ cells to lyse HTLV-1 infected cells which expressed the viral sense strand gene products was significantly enhanced after in vitro culture, and donors with an ATL clone that expressed the HTLV-1 Tax gene were most likely to make a detectable lytic CD8+ response to the ATL cells. We conclude that some patients with ATL possess functional tumour-specific CTLs which could be exploited to contribute to control of the disease.
Kirk PDW, Huvet M, Melamed A, et al., 2016, Retroviruses integrate into a shared, non-palindromic DNA motif, Nature Microbiology, Vol: 2, Pages: 1-6, ISSN: 2058-5276
Many DNA-binding factors, such as transcription factors, form oligomeric complexes with structural symmetry that bind to palindromic DNA sequences1. Palindromic consensus nucleotide sequences are also found at the genomic integration sites of retroviruses2,3,4,5,6 and other transposable elements7,8,9, and it has been suggested that this palindromic consensus arises as a consequence of the structural symmetry in the integrase complex2,3. However, we show here that the palindromic consensus sequence is not present in individual integration sites of human T-cell lymphotropic virus type 1 (HTLV-1) and human immunodeficiency virus type 1 (HIV-1), but arises in the population average as a consequence of the existence of a non-palindromic nucleotide motif that occurs in approximately equal proportions on the plus strand and the minus strand of the host genome. We develop a generally applicable algorithm to sort the individual integration site sequences into plus-strand and minus-strand subpopulations, and use this to identify the integration site nucleotide motifs of five retroviruses of different genera: HTLV-1, HIV-1, murine leukaemia virus (MLV), avian sarcoma leucosis virus (ASLV) and prototype foamy virus (PFV). The results reveal a non-palindromic motif that is shared between these retroviruses.
Zhyvoloup A, Melamed A, Anderson I, et al., 2016, A capsid-dependent integration program linking T cell activation to HIV-1 gene expression, Publisher: BIOMED CENTRAL LTD, ISSN: 1742-4690
Satou Y, Miyazato P, Ishihara Y, et al., 2016, The retrovirus HTLV-1 inserts an ectopic CTCF-binding site into the human genome, Proceedings of the National Academy of Sciences of the United States of America, Vol: 113, Pages: 3054-3059, ISSN: 0027-8424
Human T-lymphotropic virus type 1 (HTLV-1) is a retrovirus thatcauses malignant and inflammatory diseases in 10% of infectedpeople. A typical host has between 104and 105clones of HTLV-1-infected T lymphocytes, each clone distinguished by the genomicintegration site of the single-copy HTLV-1 provirus. TheHBZgeneis constitutively expressed from the minus strand of the provirus,whereas plus-strand expression, required for viral propagation touninfected cells, is suppressed or intermittentin vivo, allowingescape from host immune surveillance. It remains unknown whatregulates this pattern of proviral transcription and latency. Herewe show that CTCF, a key regulator of chromatin structure andfunction, binds to the provirus at a sharp border in epigeneticmodifications in the pX region of the HTLV-1 provirus, in T cellsnaturally infected with HTLV-1. CTCF is a zinc-finger protein thatbinds to an insulator region in genomic DNA and plays a funda-mental role in controlling higher-order chromatin structure andgene expression in vertebrate cells. We show that CTCF boundto HTLV-1 acts as an enhancer blocker, regulates HTLV-1 mRNAsplicing, and forms long-distance interactions with flanking hostchromatin. CTCF binding sites have been propagated through-out the genome by transposons in certain primate lineages, butCTCF binding has not previously been described in present-dayexogenous retroviruses. The presence of an ectopic CTCF bindingsite introduced by the retrovirus in tens of thousands of genomiclocations has the potential to cause widespread abnormalities inhost cell chromatin structure and gene expression.
Cook LBM, Melamed A, Demontis MA, et al., 2016, Rapid dissemination of human T-lymphotropic virus type 1 during primary infection in transplant recipients, Retrovirology, Vol: 13, ISSN: 1742-4690
BackgroundHuman T-lymphotropic virus type 1 (HTLV-1) infects an estimated 10 million persons globally with transmission resulting in lifelong infection. Disease, linked to high proviral load, occurs in a minority. In established infection HTLV-1 replicates through infectious spread and clonal expansion of infected lymphocytes. Little is known about acute HTLV-1 infection. The kinetics of early HTLV-1 infection, following transplantation-acquired infection in three recipients from one HTLV-1 infected donor, is reported. The recipients were treated with two HTLV-1 enzyme inhibitors 3 weeks post exposure following the detection of HTLV-1 provirus at low level in each recipient. HTLV-1 infection was serially monitored by serology, quantification of proviral load and HTLV-1 2LTR DNA circles and by HTLV-1 unique integration site analysis.ResultsHTLV-1 antibodies were first detected 16–39 days post-transplantation. HTLV-1 provirus was detected by PCR on day 16–23 and increased by 2–3 log by day 38–45 with a peak proviral doubling time of 1.4 days, after which steady state was reached. The rapid proviral load expansion was associated with high frequency of HTLV-1 2LTR DNA circles. The number of HTLV-1 unique integration sites was high compared with established HTLV-1 infection. Clonal expansion of infected cells was detected as early as day 37 with high initial oligoclonality index, consistent with early mitotic proliferation.ConclusionsIn recipients infected through organ transplantation HTLV-1 disseminated rapidly despite early anti-HTLV-1 treatment. Proviral load set point was reached within 6 weeks. Seroconversion was not delayed. Unique integration site analysis and HTLV-1 2LTR DNA circles indicated early clonal expansion and high rate of infectious spread.
Bangham CRM, Melamed A, Laydon D, et al., 2015, HTLV-1 drives vigorous clonal expansion of infected CD8 + T cells in natural infection, Retrovirology, Vol: 12, ISSN: 1742-4690
BackgroundHuman T-lymphotropic Virus Type I (HTLV-1) is a retrovirus that persistently infects 5–10 million individuals worldwide and causes disabling or fatal inflammatory and malignant diseases. The majority of the HTLV-1 proviral load is found in CD4 + T cells, and the phenotype of adult T cell leukemia (ATL) is typically CD4 + . HTLV-1 also infects CD8 + cells in vivo, but the relative abundance and clonal composition of the two infected subpopulations have not been studied. We used a high-throughput DNA sequencing protocol to map and quantify HTLV-1 proviral integration sites in separated populations of CD4 + cells, CD8 + cells and unsorted peripheral blood mononuclear cells from 12 HTLV-1-infected individuals.ResultsWe show that the infected CD8 + cells constitute a median of 5 % of the HTLV-1 proviral load. However, HTLV-1-infected CD8 + clones undergo much greater oligoclonal proliferation than the infected CD4 + clones in infected individuals, regardless of disease manifestation. The CD8 + clones are over-represented among the most abundant clones in the blood and are redetected even after several years.ConclusionsWe conclude that although they make up only 5 % of the proviral load, the HTLV-1-infected CD8 + T-cells make a major impact on the clonal composition of HTLV-1-infected cells in the blood. The greater degree of oligoclonal expansion observed in the infected CD8 + T cells, contrasts with the CD4 + phenotype of ATL; cases of CD8 + adult T-cell leukaemia/lymphoma are rare. This work is consistent with growing evidence that oligoclonal expansion of HTLV-1-infected cells is not sufficient for malignant transformation.
Turpin J, Alais S, Marçais A, et al., 2015, Traitement d’un lymphome agressif chez un babouin naturellement infecté par STLV-1, Revue de primatologie
Niederer HA, Laydon DJ, Melamed A, et al., 2014, HTLV-1 proviral integration sites differ between asymptomatic carriers and patients with HAM/TSP, Virology Journal, Vol: 11, ISSN: 1743-422X
Background: HTLV-1 causes proliferation of clonal populations of infected T cells in vivo, each clone defined by aunique proviral integration site in the host genome. The proviral load is strongly correlated with odds of theinflammatory disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). There is evidence thatasymptomatic HTLV-1 carriers (ACs) have a more effective CD8 + T cell response, including a higher frequency ofHLA class I alleles able to present peptides from a regulatory protein of HTLV-1, HBZ. We have previously shownthat specific features of the host genome flanking the proviral integration site favour clone survival and spontaneousexpression of the viral transactivator protein Tax in naturally infected PBMCs ex vivo. However, the previous studies werenot designed or powered to detect differences in integration site characteristics between ACs and HAM/TSP patients.Here, we tested the hypothesis that the genomic environment of the provirus differs systematically between ACs andHAM/TSP patients, and between individuals with strong or weak HBZ presentation.Methods: We used our recently described high-throughput protocol to map and quantify integration sites in 95 HAM/TSP patients and 68 ACs from Kagoshima, Japan, and 75 ACs from Kumamoto, Japan. Individuals with 2 or more HLAclass I alleles predicted to bind HBZ peptides were classified ‘strong’ HBZ binders; the remainder were classified ‘weakbinders’.Results: The abundance of HTLV-1-infected T cell clones in vivo was correlated with proviral integration in genes andin areas with epigenetic marks associated with active regulatory elements. In clones of equivalent abundance, integrationsites in genes and active regions were significantly more frequent in ACs than patients with HAM/TSP, irrespectiveof HBZ binding and proviral load. Integration sites in genes were also more frequent in strong HBZ binders than weakHBZ binders.Conclusion: Clonal abundance is correl
Cook LB, Melamed A, Niederer H, et al., 2014, The role of HTLV-1 clonality, proviral structure, and genomic integration site in adult T-cell leukemia/lymphoma, Blood, Vol: 123, Pages: 3925-3931, ISSN: 0006-4971
Adult T-cell leukemia/lymphoma (ATL) occurs in ∼5% of human T-lymphotropic virus type 1 (HTLV-1)–infected individuals and is conventionally thought to be a monoclonal disease in which a single HTLV-1+ T-cell clone progressively outcompetes others and undergoes malignant transformation. Here, using a sensitive high-throughput method, we quantified clonality in 197 ATL cases, identified genomic characteristics of the proviral integration sites in malignant and nonmalignant clones, and investigated the proviral features (genomic structure and 5′ long terminal repeat methylation) that determine its capacity to express the HTLV-1 oncoprotein Tax. Of the dominant, presumed malignant clones, 91% contained a single provirus. The genomic characteristics of the integration sites in the ATL clones resembled those of the frequent low-abundance clones (present in both ATL cases and carriers) and not those of the intermediate-abundance clones observed in 24% of ATL cases, suggesting that oligoclonal proliferation per se does not cause malignant transformation. Gene ontology analysis revealed an association in 6% of cases between ATL and integration near host genes in 3 functional categories, including genes previously implicated in hematologic malignancies. In all cases of HTLV-1 infection, regardless of ATL, there was evidence of preferential survival of the provirus in vivo in acrocentric chromosomes (13, 14, 15, 21, and 22).
Bangham CRM, Cook LB, Melamed A, 2014, HTLV-1 clonality in adult T-cell leukaemia and non-malignant HTLV-1 infection, Seminars in Cancer Biology, Vol: 26, Pages: 89-98, ISSN: 1044-579X
Human T lymphotropic virus type 1 (HTLV-1) causes a range of chronic inflammatory diseases and an aggressive malignancy of T lymphocytes known as adult T-cell leukaemia/lymphoma (ATLL). A cardinal feature of HTLV-1 infection is the presence of expanded clones of HTLV-1-infected T cells, which may persist for decades. A high viral burden (proviral load) is associated with both the inflammatory and malignant diseases caused by HTLV-1, and it has been believed that the oligoclonal expansion of infected cells predisposes to these diseases. However, it is not understood what regulates the clonality of HTLV-1 in vivo, that is, the number and abundance of HTLV-1-infected T cell clones. We review recent advances in the understanding of HTLV-1 infection and disease that have come from high-throughput quantification and analysis of HTLV-1 clonality in natural infection.
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