-
Retrovirology Aug 2019Human 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... (Comparative Study)
Comparative Study Review
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.
Topics: HTLV-I Infections; HTLV-II Infections; Human T-lymphotropic virus 1; Human T-lymphotropic virus 2; Humans; Leukemia-Lymphoma, Adult T-Cell; Leukocytes, Mononuclear; Paraparesis, Tropical Spastic
PubMed: 31391116
DOI: 10.1186/s12977-019-0483-0 -
International Journal of Molecular... Jul 2021Since the discovery of the human T-cell leukemia virus-1 (HTLV-1), cellular and animal models have provided invaluable contributions in the knowledge of viral infection,... (Review)
Review
Since the discovery of the human T-cell leukemia virus-1 (HTLV-1), cellular and animal models have provided invaluable contributions in the knowledge of viral infection, transmission and progression of HTLV-associated diseases. HTLV-1 is the causative agent of the aggressive adult T-cell leukemia/lymphoma and inflammatory diseases such as the HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). Cell models contribute to defining the role of HTLV proteins, as well as the mechanisms of cell-to-cell transmission of the virus. Otherwise, selected and engineered animal models are currently applied to recapitulate in vivo the HTLV-1 associated pathogenesis and to verify the effectiveness of viral therapy and host immune response. Here we review the current cell models for studying virus-host interaction, cellular restriction factors and cell pathway deregulation mediated by HTLV products. We recapitulate the most effective animal models applied to investigate the pathogenesis of HTLV-1-associated diseases such as transgenic and humanized mice, rabbit and monkey models. Finally, we summarize the studies on STLV and BLV, two closely related HTLV-1 viruses in animals. The most recent anticancer and HAM/TSP therapies are also discussed in view of the most reliable experimental models that may accelerate the translation from the experimental findings to effective therapies in infected patients.
Topics: Animals; Disease Models, Animal; HTLV-I Infections; Human T-lymphotropic virus 1; Humans; Leukemia-Lymphoma, Adult T-Cell; Mice; Mice, Transgenic
PubMed: 34360767
DOI: 10.3390/ijms22158001 -
Frontiers in Immunology 2022HTLV-1 is a global infection with 5-20 million infected individuals. Although only a minority of infected individuals develop myelopathy, lymphoproliferative malignancy,... (Review)
Review
HTLV-1 is a global infection with 5-20 million infected individuals. Although only a minority of infected individuals develop myelopathy, lymphoproliferative malignancy, or inflammatory disorders, infection is associated with immunosuppression and shorter survival. Transmission of HTLV-1 is through contaminated blood or needles, mother-to-child exposure through breast-feeding, and sexual intercourse. HTLV-1 is a delta retrovirus that expresses immunogenic Gag, Envelope, TAX, and Hbz proteins. Neutralizing antibodies have been identified directed against the surface envelope protein, and cytotoxic T-cell epitopes within TAX have been characterized. Thus far, there have been few investigations of vaccines directed against each of these proteins, with limited responses, thus far. However, with new technologies developed in the last few years, a renewed investigation is warranted in search for a safe and effective HTLV-1 vaccine.
Topics: Antibodies, Neutralizing; Epitopes, T-Lymphocyte; Female; HTLV-I Infections; Human T-lymphotropic virus 1; Humans; Infectious Disease Transmission, Vertical; Vaccines
PubMed: 36159878
DOI: 10.3389/fimmu.2022.953650 -
Bioscience Reports Mar 2022Human T-cell leukemia virus type 1 (HTLV-1) is the only identified oncogenic human retrovirus. HTLV-1 infects approximately 5-10 million people worldwide and is the... (Review)
Review
Human T-cell leukemia virus type 1 (HTLV-1) is the only identified oncogenic human retrovirus. HTLV-1 infects approximately 5-10 million people worldwide and is the infectious cause of adult T-cell leukemia/lymphoma (ATL) and several chronic inflammatory diseases, including HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), dermatitis, and uveitis. Unlike other oncogenic retroviruses, HTLV-1 does not capture a cellular proto-oncogene or induce proviral insertional mutagenesis. HTLV-1 is a trans-activating retrovirus and encodes accessory proteins that induce cellular transformation over an extended period of time, upwards of several years to decades. Inarguably the most important viral accessory protein involved in transformation is Tax. Tax is a multifunctional protein that regulates several different pathways and cellular processes. This single viral protein is able to modulate viral gene expression, activate NF-κB signaling pathways, deregulate the cell cycle, disrupt apoptosis, and induce genomic instability. The summation of these processes results in cellular transformation and virus-mediated oncogenesis. Interestingly, HTLV-1 also encodes a protein called Hbz from the antisense strand of the proviral genome that counters many Tax functions in the infected cell, such as Tax-mediated viral transcription and NF-κB activation. However, Hbz also promotes cellular proliferation, inhibits apoptosis, and disrupts genomic integrity. In addition to viral proteins, there are other cellular factors such as MEF-2, superoxide-generating NAPDH oxidase 5-α (Nox5α), and PDLIM2 which have been shown to be critical for HTLV-1-mediated T-cell transformation. This review will highlight the important viral and cellular factors involved in HTLV-1 transformation and the available in vitro and in vivo tools used to study this complex process.
Topics: Adult; Basic-Leucine Zipper Transcription Factors; Human T-lymphotropic virus 1; Humans; LIM Domain Proteins; Microfilament Proteins; NF-kappa B; Paraparesis, Tropical Spastic; Retroviridae Proteins; Viral Proteins
PubMed: 35169839
DOI: 10.1042/BSR20211921 -
Viruses Jul 2020Basic leucine zipper (bZIP) transcription factors (TFs) govern diverse cellular processes and cell fate decisions. The hallmark of the leucine zipper domain is the... (Review)
Review
Basic leucine zipper (bZIP) transcription factors (TFs) govern diverse cellular processes and cell fate decisions. The hallmark of the leucine zipper domain is the heptad repeat, with leucine residues at every seventh position in the domain. These leucine residues enable homo- and heterodimerization between ZIP domain α-helices, generating coiled-coil structures that stabilize interactions between adjacent DNA-binding domains and target DNA substrates. Several cancer-causing viruses encode viral bZIP TFs, including human T-cell leukemia virus (HTLV), hepatitis C virus (HCV) and the herpesviruses Marek's disease virus (MDV), Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV). Here, we provide a comprehensive review of these viral bZIP TFs and their impact on viral replication, host cell responses and cell fate.
Topics: Animals; Basic-Leucine Zipper Transcription Factors; Deltaretrovirus; Herpesvirus 4, Human; Herpesvirus 8, Human; Humans; Mardivirus; Oncogenic Viruses; Phylogeny; Tumor Virus Infections; Unfolded Protein Response
PubMed: 32674309
DOI: 10.3390/v12070757 -
Viruses Apr 2022HTLV-1 uveitis (HU) is the third clinical entity to be designated as an HTLV-1-associated disease. Although HU is considered to be the second-most frequent... (Review)
Review
HTLV-1 uveitis (HU) is the third clinical entity to be designated as an HTLV-1-associated disease. Although HU is considered to be the second-most frequent HTLV-1-associated disease in Japan, information on HU is limited compared to that on adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy (HAM). Recent studies have addressed several long-standing uncertainties about HU. HTLV-1-related diseases are known to be caused mainly through vertical transmission (mother-to-child transmission), but emerging HTLV-1 infection by horizontal transmission (such as sexual transmission) has become a major problem in metropolitan areas, such as Tokyo, Japan. Investigation in Tokyo showed that horizontal transmission of HTLV-1 was responsible for HU with severe and persistent ocular inflammation. The development of ATL and HAM is known to be related to a high provirus load and hence involves a long latency period. On the other hand, factors contributing to the development of HU are poorly understood. Recent investigations revealed that severe HU occurs against a background of Graves' disease despite a low provirus load and short latency period. This review highlights the recent knowledge on HU and provides an update on the topic of HU in consideration of a recent nationwide survey.
Topics: Adult; Female; HTLV-I Infections; Human T-lymphotropic virus 1; Humans; Infectious Disease Transmission, Vertical; Paraparesis, Tropical Spastic; Proviruses; Uveitis
PubMed: 35458524
DOI: 10.3390/v14040794 -
Frontiers in Immunology 2022HTLV-1 is an oncovirus causing ATL and other inflammatory diseases such as HAM/TSP and HU in about 5% of infected individuals. It is also known that HTLV-1-infected... (Review)
Review
HTLV-1 is an oncovirus causing ATL and other inflammatory diseases such as HAM/TSP and HU in about 5% of infected individuals. It is also known that HTLV-1-infected cells maintain a disease-free, immortalized, latent state throughout the lifetimes of about 95% of infected individuals. We believe that the stable maintenance of disease-free infected cells in the carrier is an intrinsic characteristic of HTLV-1 that has been acquired during its evolution in the human life cycle. We speculate that the pathogenesis of the virus is ruled by the orchestrated functions of viral proteins. In particular, the regulation of Rex, the conductor of viral replication rate, is expected to be closely related to the viral program in the early active viral replication followed by the stable latency in HTLV-1 infected T cells. HTLV-1 and HIV-1 belong to the family and share the same tropism, e.g., human CD4 T cells. These viruses show significant similarities in the viral genomic structure and the molecular mechanism of the replication cycle. However, HTLV-1 and HIV-1 infected T cells show different phenotypes, especially in the level of virion production. We speculate that how the activity of HTLV-1 Rex and its counterpart HIV-1 Rev are regulated may be closely related to the properties of respective infected T cells. In this review, we compare various pathological aspects of HTLV-1 and HIV-1. In particular, we investigated the presence or absence of a virally encoded "regulatory valve" for HTLV-1 Rex or HIV-1 Rev to explore its importance in the regulation of viral particle production in infected T cells. Finally, wereaffirm Rex as the key conductor for viral replication and viral pathogenesis based on our recent study on the novel functional aspects of Rex. Since the activity of Rex is closely related to the viral replication rate, we hypothesize that the "regulatory valve" on the Rex activity may have been selectively evolved to achieve the "scenario" with early viral particle production and the subsequent long, stable deep latency in HTLV-1 infected cells.
Topics: Gene Products, rex; Gene Products, tax; HIV-1; Human T-lymphotropic virus 1; Humans; Viral Proteins; Virus Replication
PubMed: 36189216
DOI: 10.3389/fimmu.2022.959962 -
Journal of Clinical and Experimental... 2021Adult T-cell leukemia/lymphoma (ATLL) is a malignancy caused by the human T-cell leukemia virus type 1. Aggressive ATLL is refractory to conventional chemotherapy and... (Review)
Review
Adult T-cell leukemia/lymphoma (ATLL) is a malignancy caused by the human T-cell leukemia virus type 1. Aggressive ATLL is refractory to conventional chemotherapy and has a poor prognosis. Better therapeutic approaches, including cancer immunotherapy, are required to improve survival and prognosis. The genetic landscape of ATLL reveals frequent genetic alterations in genes associated with immune surveillance, including major histocompatibility complex (MHC) class I, CD58 antigen, and programmed cell death ligand 1. Clinicopathological investigations also revealed tumor immunity mechanisms in ATLL, including immune checkpoint molecules, MHC molecules, tumor-associated macrophages, and chemokines. However, the tumor microenvironment of ATLL remains complex because ATLL itself originates from T-cells, usually expressing regulatory T-cell markers. In this review, we discuss the recent literature describing the tumor microenvironment of ATLL.
Topics: Human T-lymphotropic virus 1; Humans; Leukemia-Lymphoma, Adult T-Cell; Lymphoma; Prognosis; Tumor Microenvironment
PubMed: 34937829
DOI: 10.3960/jslrt.21007 -
Frontiers in Immunology 2022Human T cell leukemia virus-1 (HTLV-1) is the causative agent of a severe cancer of the lymphoid lineage that develops in 3-5% of infected individuals after many years.... (Review)
Review
Human T cell leukemia virus-1 (HTLV-1) is the causative agent of a severe cancer of the lymphoid lineage that develops in 3-5% of infected individuals after many years. HTLV-1 infection may also induce a serious inflammatory pathology of the nervous system designated HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Two virus-encoded proteins, the viral transactivator Tax-1 and the HTLV-1 basic leucine-zipper factor HBZ, are strongly involved in the oncogenic process. Tax-1 is involved in initial phases of the oncogenic process. Conversely, HBZ seems to be involved in maintenance of the neoplastic state as witnessed by the generation of leukemic/lymphomatous phenotype in HBZ transgenic mice and the persistent expression of HBZ in all phases of the oncogenic process. Nevertheless, the intimate molecular and cellular mechanism mediated by the two viral proteins, particularly HBZ, in oncogenesis still remain elusive. An important step toward the complete comprehension of HBZ-associated oncogenicity is the clarification of the anatomical correlates of HBZ during the various phases of HTLV-1 infection to development of HTLV-1-associated inflammatory pathology and ultimately to the establishment of leukemia. In this review, I will summarize recent studies that have established for the first time a temporal and unidirectional expression of HBZ, beginning with an exclusive cytoplasmic localization in infected asymptomatic individuals and in HAM/TSP patients and ending to a progressive cytoplasmic-to-nuclear transition in leukemic cells. These results are framed within the present knowledge of HTLV-1 infection and the future lines of research that may shed new light on the complex mechanism of HTLV-1- mediated oncogenesis.
Topics: Animals; Basic-Leucine Zipper Transcription Factors; Carcinogenesis; Human T-lymphotropic virus 1; Leukemia; Mice; Paraparesis, Tropical Spastic; Retroviridae Proteins; Viral Proteins
PubMed: 35812456
DOI: 10.3389/fimmu.2022.940131 -
The American Journal of Tropical... Jan 2020
Topics: Eye Diseases; Human T-lymphotropic virus 1; Humans; Leukemia-Lymphoma, Adult T-Cell; Male; Methotrexate; Middle Aged; Radiotherapy; Retinal Pigment Epithelium; Tomography, Optical Coherence
PubMed: 31971149
DOI: 10.4269/ajtmh.19-0539