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Silva De Castro I, Granato A, Mariante RM, Lima MA, Leite ACC, Espindola ODM, Pise-Masison CA, Franchini G, Linden R, Echevarria-Lima J. HTLV-1 p12 modulates the levels of prion protein (PrP C) in CD4 + T cells. Front Microbiol 2023; 14:1175679. [PMID: 37637115 PMCID: PMC10449582 DOI: 10.3389/fmicb.2023.1175679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 04/03/2023] [Indexed: 08/29/2023] Open
Abstract
Introduction Infection with human T cell lymphotropic virus type 1 (HTLV-1) is endemic in Brazil and is linked with pro-inflammatory conditions including HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a chronic neuroinflammatory incapacitating disease that culminates in loss of motor functions. The mechanisms underlying the onset and progression of HAM/TSP are incompletely understood. Previous studies have demonstrated that inflammation and infectious agents can affect the expression of cellular prion protein (PrPC) in immune cells. Methods Here, we investigated whether HTLV-1 infection affected PrPC content in cell lines and primary CD4+cells in vitro using flow cytometry and western blot assays. Results We found that HTLV-1 infection decreased the expression levels of PrPC and HTLV-1 Orf I encoded p12, an endoplasmic reticulum resident protein also known to affect post-transcriptionally cellular proteins such as MHC-class I and the IL-2 receptor. In addition, we observed a reduced percentage of CD4+ T cells from infected individuals expressing PrPC, which was reflected by IFN type II but not IL-17 expression. Discussion These results suggested that PrPC downregulation, linked to both HTLV-1 p12 and IFN-γ expression in CD4+ cells, may play a role in the neuropathogenesis of HTLV-1 infection.
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Affiliation(s)
- Isabela Silva De Castro
- Laboratório de Imunologia Básica e Aplicada, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Animal Models and Retroviral Vaccines Section, Vaccine Branch, National Cancer Institute, Bethesda, MD, United States
| | - Alessandra Granato
- Program in Genetics and Genome Biology, Hospital for Sick Children, Toronto, ON, Canada
| | - Rafael Meyer Mariante
- Laboratório de Neurogenesis, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Laboratório de Biologia Estrutural, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | - Marco Antonio Lima
- Instituto Nacional de Infectologia Evandro Chagas (INI), Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil
| | - Ana Claudia Celestino Leite
- Instituto Nacional de Infectologia Evandro Chagas (INI), Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil
| | - Otávio de Melo Espindola
- Instituto Nacional de Infectologia Evandro Chagas (INI), Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil
| | - Cynthia A. Pise-Masison
- Animal Models and Retroviral Vaccines Section, Vaccine Branch, National Cancer Institute, Bethesda, MD, United States
| | - Genoveffa Franchini
- Animal Models and Retroviral Vaccines Section, Vaccine Branch, National Cancer Institute, Bethesda, MD, United States
| | - Rafael Linden
- Laboratório de Neurogenesis, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Juliana Echevarria-Lima
- Laboratório de Imunologia Básica e Aplicada, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Ye L, Taylor GP, Rosadas C. Human T-Cell Lymphotropic Virus Type 1 and Strongyloides stercoralis Co-infection: A Systematic Review and Meta-Analysis. Front Med (Lausanne) 2022; 9:832430. [PMID: 35237633 PMCID: PMC8882768 DOI: 10.3389/fmed.2022.832430] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 01/12/2022] [Indexed: 11/13/2022] Open
Abstract
BackgroundThe distribution of human T cell lymphotropic virus type 1 (HTLV-1) overlaps with that of Strongyloides stercoralis. Strongyloides stercoralis infection has been reported to be impacted by co-infection with HTLV-1. Disseminated strongyloidiasis and hyperinfection syndrome, which are commonly fatal, are observed in HTLV-1 co-infected patients. Reduced efficacy of anti-strongyloidiasis treatment in HTLV-1 carriers has been reported. The aim of this meta-analysis and systematic review is to better understand the association between HTLV-1 and S. stercoralis infection.MethodsPubMed, Embase, MEDLINE, Global Health, Healthcare Management Information Consortium databases were searched. Studies regarding the prevalence of S. stercoralis, those evaluating the frequency of mild or severe strongyloidiasis, and treatment response in people living with and without HTLV-1 infection were included. Data were extracted and odds ratios were calculated. Random-effect meta-analysis was used to assess the pooled OR and 95% confidence intervals.ResultsFourteen studies were included after full-text reviewing of which seven described the prevalence of S. stercoralis and HTLV-1. The odds of S. stercoralis infection were higher in HTLV-1 carriers when compared with HTLV-1 seronegative subjects (OR 3.2 95%CI 1.7–6.2). A strong association was found between severe strongyloidiasis and HTLV-1 infection (OR 59.9, 95%CI 18.1–198). Co-infection with HTLV-1 was associated with a higher rate of strongyloidiasis treatment failure (OR 5.05, 95%CI 2.5–10.1).ConclusionStrongyloides stercoralis infection is more prevalent in people living with HTLV-1. Co-infected patients are more likely to develop severe presentation and to fail treatment. Screening for HTLV-1 and Strongyloides sp. should be routine when either is diagnosed.
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Affiliation(s)
- Lingqing Ye
- Section of Virology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Graham P. Taylor
- Section of Virology, Department of Infectious Disease, Imperial College London, London, United Kingdom
- National Centre for Human Retrovirology, St. Mary's Hospital, Imperial College Healthcare NHS Trust, London, United Kingdom
- *Correspondence: Graham P. Taylor
| | - Carolina Rosadas
- Section of Virology, Department of Infectious Disease, Imperial College London, London, United Kingdom
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Sarkis S, Galli V, Moles R, Yurick D, Khoury G, Purcell DFJ, Franchini G, Pise-Masison CA. Role of HTLV-1 orf-I encoded proteins in viral transmission and persistence. Retrovirology 2019; 16:43. [PMID: 31852543 PMCID: PMC6921521 DOI: 10.1186/s12977-019-0502-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/03/2019] [Indexed: 02/07/2023] Open
Abstract
The human T cell leukemia virus type 1 (HTVL-1), first reported in 1980 by Robert Gallo's group, is the etiologic agent of both cancer and inflammatory diseases. Despite approximately 40 years of investigation, the prognosis for afflicted patients remains poor with no effective treatments. The virus persists in the infected host by evading the host immune response and inducing proliferation of infected CD4+ T-cells. Here, we will review the role that viral orf-I protein products play in altering intracellular signaling, protein expression and cell-cell communication in order to escape immune recognition and promote T-cell proliferation. We will also review studies of orf-I mutations found in infected patients and their potential impact on viral load, transmission and persistence. Finally, we will compare the orf-I gene in HTLV-1 subtypes as well as related STLV-1.
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Affiliation(s)
- Sarkis Sarkis
- Animal Models and Retroviral Vaccines Section, Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Veronica Galli
- Animal Models and Retroviral Vaccines Section, Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ramona Moles
- Animal Models and Retroviral Vaccines Section, Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - David Yurick
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, VIC, Australia
| | - Georges Khoury
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, VIC, Australia
| | - Damian F J Purcell
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, VIC, Australia
| | - Genoveffa Franchini
- Animal Models and Retroviral Vaccines Section, Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Cynthia A Pise-Masison
- Animal Models and Retroviral Vaccines Section, Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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Bayliss RJ, Piguet V. Masters of manipulation: Viral modulation of the immunological synapse. Cell Microbiol 2018; 20:e12944. [PMID: 30123959 PMCID: PMC6492149 DOI: 10.1111/cmi.12944] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/01/2018] [Accepted: 08/14/2018] [Indexed: 02/06/2023]
Abstract
In order to thrive, viruses have evolved to manipulate host cell machinery for their own benefit. One major obstacle faced by pathogens is the immunological synapse. To enable efficient replication and latency in immune cells, viruses have developed a range of strategies to manipulate cellular processes involved in immunological synapse formation to evade immune detection and control T-cell activation. In vitro, viruses such as human immunodeficiency virus 1 and human T-lymphotropic virus type 1 utilise structures known as virological synapses to aid transmission of viral particles from cell to cell in a process termed trans-infection. The formation of the virological synapse provides a gateway for virus to be transferred between cells avoiding the extracellular space, preventing antibody neutralisation or recognition by complement. This review looks at how viruses are able to subvert intracellular signalling to modulate immune function to their advantage and explores the role synapse formation has in viral persistence and cell-to-cell transmission.
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Affiliation(s)
- Rebecca J. Bayliss
- Division of Infection and Immunity, School of MedicineCardiff UniversityCardiffUK
| | - Vincent Piguet
- Division of Infection and Immunity, School of MedicineCardiff UniversityCardiffUK
- Division of Dermatology, Department of MedicineUniversity of TorontoTorontoOntarioCanada
- Division of DermatologyWomen's College HospitalTorontoOntarioCanada
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Rosadas C, Vicente ACP, Zanella L, Cabral-Castro MJ, Peralta JM, Puccioni-Sohler M. First report of HTLV-1 truncated p12 protein in Brazil. Virulence 2016; 8:1445-1449. [PMID: 27960650 DOI: 10.1080/21505594.2016.1267895] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Carolina Rosadas
- a Universidade Federal do Rio de Janeiro (UFRJ) , Rio de Janeiro , Brazil
| | - Ana C P Vicente
- b Laboratory of Molecular Genetics of Microorganisms, Fundação Oswaldo Cruz (IOC - FIOCRUZ) , Rio de Janeiro , Brazil
| | - Louise Zanella
- b Laboratory of Molecular Genetics of Microorganisms, Fundação Oswaldo Cruz (IOC - FIOCRUZ) , Rio de Janeiro , Brazil
| | | | - José M Peralta
- a Universidade Federal do Rio de Janeiro (UFRJ) , Rio de Janeiro , Brazil
| | - Marzia Puccioni-Sohler
- a Universidade Federal do Rio de Janeiro (UFRJ) , Rio de Janeiro , Brazil.,c Universidade Federal do Estado do Rio de Janeiro (UNIRIO) , Rio de Janeiro , Brazil
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HTLV-1 ORF-I Encoded Proteins and the Regulation of Host Immune Response: Viral Induced Dysregulation of Intracellular Signaling. J Immunol Res 2015; 2015:498054. [PMID: 26557721 PMCID: PMC4628651 DOI: 10.1155/2015/498054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 08/22/2015] [Accepted: 08/31/2015] [Indexed: 01/02/2023] Open
Abstract
The human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus associated with both proliferative and inflammatory disorders. This virus causes a persistent infection, mainly in CD4+ T lymphocyte. The ability to persist in the host is associated with the virus capacity to evade the immune response and to induce infected T-cell proliferation, once the HTLV-1 maintains the infection mainly by clonal expansion of infected cells. There are several evidences that ORF-I encoded proteins, such as p12 and p8, play an important role in this context. The present study will review the molecular mechanisms that HTLV-1 ORF-I encoded proteins have to induce dysregulation of intracellular signaling, in order to escape from immune response and to increase the infected T-cell proliferation rate. The work will also address the impact of ORF-I mutations on the human
host and perspectives in this study field.
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Discovery and characterization of auxiliary proteins encoded by type 3 simian T-cell lymphotropic viruses. J Virol 2014; 89:931-51. [PMID: 25355890 DOI: 10.1128/jvi.02150-14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
UNLABELLED Human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 encode auxiliary proteins that play important roles in viral replication, viral latency, and immune escape. The presence of auxiliary protein-encoding open reading frames (ORFs) in HTLV-3, the latest HTLV to be discovered, is unknown. Simian T-cell lymphotropic virus type 3 (STLV-3) is almost identical to HTLV-3. Given the lack of HTLV-3-infected cell lines, we took advantage of STLV-3-infected cells and of an STLV-3 molecular clone to search for the presence of auxiliary transcripts. Using reverse transcriptase PCR (RT-PCR), we first uncovered the presence of three unknown viral mRNAs encoding putative proteins of 5, 8, and 9 kDa and confirmed the presence of the previously reported RorfII transcript. The existence of these viral mRNAs was confirmed by using splice site-specific RT-PCR with ex vivo samples. We showed that p5 is distributed throughout the cell and does not colocalize with a specific organelle. The p9 localization is similar to that of HTLV-1 p12 and induced a strong decrease in the calreticulin signal, similarly to HTLV-1 p12. Although p8, RorfII, and Rex-3 share an N-terminal sequence that is predicted to contain a nucleolar localization signal (NoLS), only p8 is found in the nucleolus. The p8 location in the nucleolus is linked to a bipartite NoLS. p8 and, to a lesser extent, p9 repressed viral expression but did not alter Rex-3-dependent mRNA export. Using a transformation assay, we finally showed that none of the STLV-3 auxiliary proteins had the ability to induce colony formation, while both Tax-3 and antisense protein of HTLV-3 (APH-3) promoted cellular transformation. Altogether, these results complete the characterization of the newly described primate T-lymphotropic virus type 3 (PTLV-3). IMPORTANCE Together with their simian counterparts, HTLVs form the primate T-lymphotropic viruses. HTLVs arose from interspecies transmission between nonhuman primates and humans. HTLV-1 and HTLV-2 encode auxiliary proteins that play important roles in viral replication, viral latency, and immune escape. The presence of ORFs encoding auxiliary proteins in HTLV-3 or STLV-3 genomes was unknown. Using in silico analyses, ex vivo samples, or in vitro experiments, we have uncovered the presence of 3 previously unknown viral mRNAs encoding putative proteins and confirmed the presence of a previously reported viral transcript. We characterized the intracellular localization of the four proteins. We showed that two of these proteins repress viral expression but that none of them have the ability to induce colony formation. However, both Tax and the antisense protein APH-3 promote cell transformation. Our results allowed us to characterize 4 new retroviral proteins for the first time.
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Olière S, Douville R, Sze A, Belgnaoui SM, Hiscott J. Modulation of innate immune responses during human T-cell leukemia virus (HTLV-1) pathogenesis. Cytokine Growth Factor Rev 2011; 22:197-210. [DOI: 10.1016/j.cytogfr.2011.08.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Lairmore MD, Anupam R, Bowden N, Haines R, Haynes RAH, Ratner L, Green PL. Molecular determinants of human T-lymphotropic virus type 1 transmission and spread. Viruses 2011; 3:1131-65. [PMID: 21994774 PMCID: PMC3185783 DOI: 10.3390/v3071131] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 07/01/2011] [Accepted: 07/02/2011] [Indexed: 01/23/2023] Open
Abstract
Human T-lymphotrophic virus type-1 (HTLV-1) infects approximately 15 to 20 million people worldwide, with endemic areas in Japan, the Caribbean, and Africa. The virus is spread through contact with bodily fluids containing infected cells, most often from mother to child through breast milk or via blood transfusion. After prolonged latency periods, approximately 3 to 5% of HTLV-1 infected individuals will develop either adult T-cell leukemia/lymphoma (ATL), or other lymphocyte-mediated disorders such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The genome of this complex retrovirus contains typical gag, pol, and env genes, but also unique nonstructural proteins encoded from the pX region. These nonstructural genes encode the Tax and Rex regulatory proteins, as well as novel proteins essential for viral spread in vivo such as, p30, p12, p13 and the antisense encoded HBZ. While progress has been made in the understanding of viral determinants of cell transformation and host immune responses, host and viral determinants of HTLV-1 transmission and spread during the early phases of infection are unclear. Improvements in the molecular tools to test these viral determinants in cellular and animal models have provided new insights into the early events of HTLV-1 infection. This review will focus on studies that test HTLV-1 determinants in context to full length infectious clones of the virus providing insights into the mechanisms of transmission and spread of HTLV-1.
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Affiliation(s)
- Michael D. Lairmore
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
- Comprehensive Cancer Center, The Arthur G. James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-614-292-9203; Fax: +1-614-292-6473
| | - Rajaneesh Anupam
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
| | - Nadine Bowden
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
| | - Robyn Haines
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
| | - Rashade A. H. Haynes
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
| | - Lee Ratner
- Department of Medicine, Pathology, and Molecular Microbiology, Division of Biology and Biological Sciences, Washington University School of Medicine, Campus Box 8069, 660 S. Euclid Ave., St. Louis, MO 63110, USA; E-Mail: (L.R.)
| | - Patrick L. Green
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
- Comprehensive Cancer Center, The Arthur G. James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, OH 43210, USA
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A new role for the HTLV-1 p8 protein: increasing intercellular conduits and viral cell-to-cell transmission. Viruses 2011; 3:254-259. [PMID: 21994729 PMCID: PMC3185692 DOI: 10.3390/v3030254] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 03/02/2011] [Accepted: 03/02/2011] [Indexed: 01/16/2023] Open
Abstract
Retroviruses like HIV-1 and HTLV-1 can be transmitted efficiently by direct contact between infected and target cells. For HIV-1, various modes of cell-to-cell transfer have been reported, including virological synapses, polysynapses, filopodial bridges, and nanotube-like structures. So far, only synapses and biofilms have been described for HTLV-1 transmission. Recently, Van Prooyen et al. [1] identified an additional mode of HTLV-1 transmission through cellular conduits induced by the viral accessory protein p8.
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Baydoun HH, Pancewicz J, Bai X, Nicot C. HTLV-I p30 inhibits multiple S phase entry checkpoints, decreases cyclin E-CDK2 interactions and delays cell cycle progression. Mol Cancer 2010; 9:302. [PMID: 21092281 PMCID: PMC3000403 DOI: 10.1186/1476-4598-9-302] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 11/23/2010] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Human T-cell leukemia virus type I (HTLV-I) has efficiently adapted to its host and establishes a persistent infection characterized by low levels of viral gene expression and slow proliferation of HTLV-I infected cells over decades. We have previously found that HTLV-I p30 is a negative regulator of virus expression. RESULTS In this study we show that p30 targets multiple cell cycle checkpoints resulting in a delayed entry into S phase. We found that p30 binds to cyclin E and CDK2 and prevents the formation of active cyclin E-CDK2 complexes. In turn, this decreases the phosphorylation levels of Rb and prevents the release of E2F and its transcriptional activation of genes required for G1/S transition. Our studies also show that HTLV-II p28 does not bind cyclin E and does not affect cell cycle progression. CONCLUSIONS In contrast to HTLV-I, the HTLV-II-related retrovirus is not oncogenic in humans. Here we report that the HTLV-I p30 delays cell cycle progression while its homologue, HTLV-II p28, does not, providing evidence for important differences between these two related retrovirus proteins.
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Affiliation(s)
- Hicham H Baydoun
- University of Kansas Medical Center, Department of Pathology and Laboratory Medicine, Kansas City, KS 66160, USA
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Sigalov AB. The SCHOOL of nature: IV. Learning from viruses. SELF/NONSELF 2010; 1:282-298. [PMID: 21487503 PMCID: PMC3062383 DOI: 10.4161/self.1.4.13279] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 08/04/2010] [Accepted: 08/05/2010] [Indexed: 02/05/2023]
Abstract
During the co-evolution of viruses and their hosts, the latter have equipped themselves with an elaborate immune system to defend themselves from the invading viruses. In order to establish a successful infection, replicate and persist in the host, viruses have evolved numerous strategies to counter and evade host antiviral immune responses as well as exploit them for productive viral replication. These strategies include those that modulate signaling mediated by cell surface receptors. Despite tremendous advancement in recent years, the exact molecular mechanisms underlying these critical points in viral pathogenesis remain unknown. In this work, based on a novel platform of receptor signaling, the Signaling Chain HOmoOLigomerization (SCHOOL) platform, I suggest specific mechanisms used by different viruses such as human immunodeficiency virus (HIV), cytomegalovirus (CMV), severe acute respiratory syndrome coronavirus, human herpesvirus 6 and others, to modulate receptor signaling. I also use the example of HIV and CMV to illustrate how two unrelated enveloped viruses use a similar SCHOOL mechanism to modulate the host immune response mediated by two functionally different receptors: T cell antigen receptor and natural killer cell receptor, NKp30. This suggests that it is very likely that similar general mechanisms can be or are used by other viral and possibly non-viral pathogens. Learning from viruses how to target cell surface receptors not only helps us understand viral strategies to escape from the host immune surveillance, but also provides novel avenues in rational drug design and the development of new therapies for immune disorders.
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Van Prooyen N, Andresen V, Gold H, Bialuk I, Pise-Masison C, Franchini G. Hijacking the T-cell communication network by the human T-cell leukemia/lymphoma virus type 1 (HTLV-1) p12 and p8 proteins. Mol Aspects Med 2010; 31:333-43. [PMID: 20673780 DOI: 10.1016/j.mam.2010.07.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 07/22/2010] [Accepted: 07/23/2010] [Indexed: 12/14/2022]
Abstract
The non-structural proteins encoded by the orf-I, II, III, and IV genes of the human T-cell leukemia/lymphoma virus type 1 (HTLV-1) genome, are critical for the modulation of cellular gene expression and T-cell proliferation, the escape from cytotoxic T-cells and natural killer cells, and virus expression. In here, we review the main functions of the HTLV-1 orf-I products. The 12kDa product from orf-I (p12) is proteolytically cleaved within the endoplasmic reticulum (ER) to generate the 8kDa protein (p8). At the steady state, both proteins are expressed at similar levels in transfected T-cells. The p12 protein remains in the ER and cis-Golgi, whereas the p8 protein traffics to the cell surface and is recruited to the immunological synapse. The p12 and the p8 proteins have seemingly opposite effects on T-cells; the ER resident p12, modulates T-cell activation and proliferation, whereas p8 induces T-cell anergy. The p8 protein also increases the formation of cellular conduits, is transferred to neighboring T-cells, and increases virus transmission. The requirement for HTLV-1 infectivity of orf-I is demonstrated by the loss of virus infectivity in macaques exposed to an engineered virus, whereby expression of orf-I was ablated. Altogether the current knowledge demonstrates that the concerted activity of p8 and p12 is essential for the persistence of virus infected cells in the host.
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Affiliation(s)
- Nancy Van Prooyen
- Animal Models and Retroviral Vaccine Section, Vaccine Branch, National Cancer Institute, National Institute of Health, Bethesda, MD 20892-5065, USA
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Requirement of the human T-cell leukemia virus p12 and p30 products for infectivity of human dendritic cells and macaques but not rabbits. Blood 2010; 116:3809-17. [PMID: 20647569 DOI: 10.1182/blood-2010-05-284141] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The identification of the genes necessary for human T-cell leukemia virus (HTLV-1) persistence in humans may provide targets for therapeutic approaches. We demonstrate that ablation of the HTLV-1 genes encoding p12, p30, or the HBZ protein, does not affect viral infectivity in rabbits and in this species, only the absence of HBZ is associated with a consistent reduction in virus levels. We observed reversion of the HTLV-1 mutants to the HTLV-1 wild-type genotype in none of the inoculated rabbits. In contrast, in macaques, the absence of HBZ was associated with reversion of the mutant virus to the wild-type genotype in 3 of the 4 animals within weeks from infection. Similarly, reversion to the wild type was observed in 2 of the 4 macaque inoculated with the p30 mutant. The 4 macaques exposed to the p12 knock remained seronegative, and only 2 animals were positive at a single time point for viral DNA in tissues. Interestingly, we found that the p12 and the p30 mutants were also severely impaired in their ability to replicate in human dendritic cells. These data suggest that infection of dendritic cells may be required for the establishment and maintenance of HTLV-1 infection in primate species.
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Vesicle traffic to the immunological synapse: a multifunctional process targeted by lymphotropic viruses. Curr Top Microbiol Immunol 2010; 340:191-207. [PMID: 19960315 DOI: 10.1007/978-3-642-03858-7_10] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The site of contact between T lymphocytes and antigen-presenting cells becomes, upon antigen recognition, an organized junction named the immunological synapse. Various T cell organelles polarize, together with microtubules, toward the antigen-presenting cell. Among them, intracellular vesicular compartments, such as the Golgi apparatus, the recycling endosomal compartment, or cytotoxic granules help to build the immunological synapse and ensure effector functions, such as polarized secretion of cytokines by helper T cells, or exocytosis of lytic granules by cytotoxic T cells. Lymphotropic retroviruses, such as the human immunodeficiency virus type 1, the human T cell leukemia virus type 1, or the Herpesvirus saimiri, can subvert some of the vesicle traffic mechanisms impeding the generation and function of the immunological synapses. This review focuses on the polarization of vesicle traffic, its regulation, and its role in maintaining the structure and function of the immunological synapse. We discuss how some lymphotropic viruses target the vesicle traffic in T lymphocytes, inhibiting the formation of immunological synapses and modulating the response of infected T cells.
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16
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Abstract
Human T-lymphotropic virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma, and it encodes a number of nonstructural proteins that are involved in virus replication and immune evasion. The viral protein p12 previously has been characterized to interfere with major histocompatibility complex class, ICAM-1, and ICAM-2 expression, and it activates STAT5. Using a previously established T-cell line immortalized with an HTLV-1 molecular clone deleted for p12, we assessed the role of p12 in regulating cellular growth and virus transmission. These cells were complemented for p12 expression by the transduction of a lentivirus vector expressing p12. We report that p12 conferred a selective growth advantage in vitro and increased the colony formation of human T cells in soft-agar assays. Consistently with previous studies, p12- and p12+ cell lines produced similar amounts of virus particles released into the supernatant of cultured cells, although we found that p12 expression greatly enhanced virus transmission. Moreover, we found that interleukin-2 (IL-2) stimulation also increased HTLV-1 transmission whether p12 was expressed or not, and inversely, that the inhibition of Jak signaling significantly reduced HTLV-1 transmission. Intriguingly, IL-2/Jak signaling was not associated with changes in viral gene expression, viral RNA encapsidation, the maturation of the virus particle, cell-cell adherence, or Gag polarization and virological synapse formation. We do demonstrate, however, that IL-2 stimulation and p12 expression significantly increased the rate of syncytium formation, revealing a novel role for IL-2 signaling and Jak activation in HTLV-1 virus transmission.
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Montes M, Sanchez C, Verdonck K, Lake JE, Gonzalez E, Lopez G, Terashima A, Nolan T, Lewis DE, Gotuzzo E, White AC. Regulatory T cell expansion in HTLV-1 and strongyloidiasis co-infection is associated with reduced IL-5 responses to Strongyloides stercoralis antigen. PLoS Negl Trop Dis 2009; 3:e456. [PMID: 19513105 PMCID: PMC2686100 DOI: 10.1371/journal.pntd.0000456] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Accepted: 05/14/2009] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Human strongyloidiasis varies from a chronic but limited infection in normal hosts to hyperinfection in patients treated with corticosteroids or with HTLV-1 co-infection. Regulatory T cells dampen immune responses to infections. How human strongyloidiasis is controlled and how HTLV-1 infection affects this control are not clear. We hypothesize that HTLV-1 leads to dissemination of Strongyloides stercoralis infection by augmenting regulatory T cell numbers, which in turn down regulate the immune response to the parasite. OBJECTIVE To measure peripheral blood T regulatory cells and Strongyloides stercoralis larval antigen-specific cytokine responses in strongyloidiasis patients with or without HTLV-1 co-infection. METHODS Peripheral blood mononuclear cells (PBMCs) were isolated from newly diagnosed strongyloidiasis patients with or without HTLV-1 co-infection. Regulatory T cells were characterized by flow cytometry using intracellular staining for CD4, CD25 and FoxP3. PBMCs were also cultured with and without Strongyloides larval antigens. Supernatants were analyzed for IL-5 production. RESULTS Patients with HTLV-1 and Strongyloides co-infection had higher parasite burdens. Eosinophil counts were decreased in the HTLV-1 and Strongyloides co-infected subjects compared to strongyloidiasis-only patients (70.0 vs. 502.5 cells/mm(3), p = 0.09, Mann-Whitney test). The proportion of regulatory T cells was increased in HTLV-1 positive subjects co-infected with strongyloidiasis compared to patients with only strongyloidiasis or asymptomatic HTLV-1 carriers (median = 17.9% vs. 4.3% vs. 5.9 p<0.05, One-way ANOVA). Strongyloides antigen-specific IL-5 responses were reduced in strongyloidiasis/HTLV-1 co-infected patients (5.0 vs. 187.5 pg/ml, p = 0.03, Mann-Whitney test). Reduced IL-5 responses and eosinophil counts were inversely correlated to the number of CD4+CD25+FoxP3+ cells. CONCLUSIONS Regulatory T cell counts are increased in patients with HTLV-1 and Strongyloides stercoralis co-infection and correlate with both low circulating eosinophil counts and reduced antigen-driven IL-5 production. These findings suggest a role for regulatory T cells in susceptibility to Strongyloides hyperinfection.
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Affiliation(s)
- Martin Montes
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
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18
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In vivo genetic mutations define predominant functions of the human T-cell leukemia/lymphoma virus p12I protein. Blood 2008; 113:3726-34. [PMID: 18791162 DOI: 10.1182/blood-2008-04-146928] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human T-cell leukemia/lymphoma virus type 1 (HTLV-1) ORF-I encodes a 99-amino acid hydrophobic membrane protein, p12(I), that affects receptors in different cellular compartments. We report here that proteolytic cleavage dictates different cellular localization and functions of p12(I). The removal of a noncanonical endoplasmic reticulum (ER) retention/retrieval signal within the amino terminus of p12(I) is necessary for trafficking to the Golgi apparatus and generation of a completely cleaved 8-kDa protein. The 8-kDa protein in turn traffics to the cell surface, is recruited to the immunologic synapse following T-cell receptor (TCR) ligation, and down-regulates TCR proximal signaling. The uncleaved 12-kDa form of p12(I) resides in the ER and interacts with the beta and gamma(c) chains of the interleukin-2 receptor (IL-2R), the heavy chain of the major histocompatibility complex (MHC) class I, as well as calreticulin and calnexin. Genetic analysis of ORF-I from ex vivo samples of HTLV-1-infected patients reveals predominant amino acid substitutions within ORF-I that affect proteolytic cleavage, suggesting that ER-associated functions of p12(I) may contribute to the survival and proliferation of the infected T cells in the host.
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19
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20
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Barbeau B, Mesnard JM. Does the HBZ gene represent a new potential target for the treatment of adult T-cell leukemia? Int Rev Immunol 2008; 26:283-304. [PMID: 18027202 DOI: 10.1080/08830180701690843] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Links between human T-cell leukemia virus type 1 and adult T-cell leukemia (ATL) were first suspected in 1980. Provirus integration has since been found in all ATL cells. Although the viral Tax protein is involved in the proliferation of the infected cells during the preleukemic stage, Tax expression is not systematically detected in primary leukemic cells. Recent studies found that the viral HBZ gene was always expressed in leukemic cells, suggesting its involvement in the progression of the infected cells toward malignancy. How could this new discovery be translated into possible new avenues for the prevention or treatment of ATL?
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Affiliation(s)
- Benoit Barbeau
- Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Canada
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21
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Kim WM, Sigalov AB. Viral pathogenesis, modulation of immune receptor signaling and treatment. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 640:325-49. [PMID: 19065800 PMCID: PMC7122915 DOI: 10.1007/978-0-387-09789-3_22] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
During the co-evolution of viruses and their hosts, the latter have equipped themselves with an elaborate immune system to defend themselves from the invading viruses. In order to establish a successful infection, replicate and persist in the host, viruses have evolved numerous strategies to counter and evade host antiviral immune responses as well as exploit them for productive viral replication. These strategies include those that target immune receptor transmembrane signaling. Uncovering the exact molecular mechanisms underlying these critical points in viral pathogenesis will not only help us understand strategies used by viruses to escape from the host immune surveillance but also reveal new therapeutic targets for antiviral as well as immunomodulatory therapy. In this chapter, based on our current understanding of transmembrane signal transduction mediated by multichain immune recognition receptors (MIRRs) and the results of sequence analysis, we discuss the MIRR-targetingviral strategies of immune evasion and suggest their possible mechanisms that, in turn, reveal new points of antiviral intervention. We also show how two unrelated enveloped viruses, human immunodeficiency virus and human cytomegalovirus, use a similar mechanism to modulate the host immune response mediated by two functionally different MIRRs-T-cell antigen receptor and natural killer cell receptor, NKp30. This suggests that it is very likely that similar general mechanisms can be or are used by other viral and possibly nonviral pathogens.
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Affiliation(s)
- Walter M Kim
- Department of Pathology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
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22
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Abstract
Human T-cell lymphotropic virus-I (HTLV-I) is the cause of adult T-cell leukaemia/lymphoma. Various viral proteins, especially, but not exclusively, Tax have been implicated in oncogenesis, mostly through in vitro studies. Tax transactivates a large and apparently ever expanding list of human genes through transcriptional factors. Elucidating not only the pathways but also the timing of action of HTLV proteins is important for understanding the pathogenesis and development of new treatments.
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Affiliation(s)
- G Taylor
- Infectious Diseases Section, Division of Medicine Faculty, St Mary's Campus, Imperial College London, London, UK.
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23
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Banerjee P, Feuer G, Barker E. Human T-cell leukemia virus type 1 (HTLV-1) p12I down-modulates ICAM-1 and -2 and reduces adherence of natural killer cells, thereby protecting HTLV-1-infected primary CD4+ T cells from autologous natural killer cell-mediated cytotoxicity despite the reduction of major histocompatibility complex class I molecules on infected cells. J Virol 2007; 81:9707-17. [PMID: 17609265 PMCID: PMC2045425 DOI: 10.1128/jvi.00887-07] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Although natural killer (NK) cell-mediated control of viral infections is well documented, very little is known about the ability of NK cells to restrain human T-cell leukemia virus type 1 (HTLV-1) infection. In the current study we show that NK cells are unable to kill HTLV-1-infected primary CD4+ T cells. Exposure of NK cells to interleukin-2 (IL-2) resulted in only a marginal increase in their ability to kill HTLV-1-infected primary CD4+ T cells. This inability of NK cells to kill HTLV-1-infected CD4+ T cells occurred despite the down-modulation of major histocompatibility complex (MHC) class I molecules, one of the ligands for the major NK cell inhibitory receptor, by HTLV-1 p12(I) on CD4+ T cells. One reason for this diminished ability of NK cells to kill HTLV-1-infected cells was the decreased ability of NK cells to adhere to HTLV-1-infected cells because of HTLV-1 p12(I)-mediated down-modulation of intercellular adhesion molecule 1 (ICAM-1) and ICAM-2. We also found that HTLV-1-infected CD4+ T cells did not express ligands for NK cell activating receptors, NCR and NKG2D, although they did express ligands for NK cell coactivating receptors, NTB-A and 2B4. Thus, despite HTLV-1-mediated down-modulation of MHC-I molecules, HTLV-1-infected primary CD4+ T cells avoids NK cell destruction by modulating ICAM expression and shunning the expression of ligands for activating receptors.
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MESH Headings
- Antigens, CD/biosynthesis
- Antigens, CD/immunology
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CD4-Positive T-Lymphocytes/virology
- Cell Adhesion/drug effects
- Cell Adhesion/immunology
- Cell Adhesion Molecules/biosynthesis
- Cell Adhesion Molecules/immunology
- Cell Line
- Coculture Techniques
- Down-Regulation/drug effects
- Down-Regulation/immunology
- HTLV-I Infections/immunology
- HTLV-I Infections/metabolism
- Histocompatibility Antigens Class I/biosynthesis
- Histocompatibility Antigens Class I/immunology
- Human T-lymphotropic virus 1/immunology
- Human T-lymphotropic virus 1/metabolism
- Humans
- Immunity, Cellular/drug effects
- Intercellular Adhesion Molecule-1/biosynthesis
- Intercellular Adhesion Molecule-1/immunology
- Interleukin-2/pharmacology
- Killer Cells, Natural/immunology
- Killer Cells, Natural/metabolism
- Ligands
- Membrane Glycoproteins/biosynthesis
- Membrane Glycoproteins/immunology
- NK Cell Lectin-Like Receptor Subfamily K
- Oncogene Proteins, Viral/immunology
- Oncogene Proteins, Viral/metabolism
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/immunology
- Receptors, Immunologic/biosynthesis
- Receptors, Immunologic/immunology
- Receptors, Natural Killer Cell
- Signaling Lymphocytic Activation Molecule Family
- Signaling Lymphocytic Activation Molecule Family Member 1
- Transcription Factors/immunology
- Transcription Factors/metabolism
- Viral Regulatory and Accessory Proteins
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Affiliation(s)
- Prabal Banerjee
- Department of Immunology and Microbiology, Rush University Medical Center, 1735 West Harrison Street, Chicago, IL 60612, USA
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24
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Deng X, Tannehill-Gregg SH, Nadella MVP, He G, Levine A, Cao Y, Rosol TJ. Parathyroid hormone-related protein and ezrin are up-regulated in human lung cancer bone metastases. Clin Exp Metastasis 2007; 24:107-19. [PMID: 17370040 DOI: 10.1007/s10585-007-9059-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Accepted: 02/16/2007] [Indexed: 10/23/2022]
Abstract
Lung cancer often metastasizes to bone in patients with advanced disease. Identification of the factors involved in the interactions between lung cancer cells and bone will improve the prevention and treatment of bone metastases. We identified changes in metastasis-related gene expression of human HARA lung squamous carcinoma cells co-cultured with neonatal mouse calvariae using a pathway-specific microarray analysis. Nine genes were up-regulated and two genes down-regulated in HARA cells co-cultured with mouse calvariae. Five of the nine up-regulated genes, including caveolin 1, CD44, EphB2, ezrin, and Parathyroid hormone-related protein (PTHrP), and one down-regulated gene, SLPI, were further confirmed by Reverse transcription-polymerase chain reaction (RT-PCR). A mouse model was subsequently used to study the role of PTHrP and ezrin in bone metastasis in vivo. PTHrP (all three isoforms) and ezrin were up-regulated in HARA cells at sites of bone metastasis as detected by RT-PCR and immunohistochemistry. The PTHrP 141 mRNA isoform was increased by the greatest extent (13.9-fold) in bone metastases compared to PTHrP 139 and PTHrP 173 mRNA. We then generated a HARA cell line in which PTHrP expression was inducibly silenced by RNA interference. Silencing of PTHrP expression caused significant reduction of submembranous F-actin and decreased HARA cell invasion. Ezrin up-regulation was confirmed by Western blots on HARA cells co-cultured with adult mouse long bones. Further, Transforming growth factor beta (TGF-beta) was identified as one of the factors in the bone microenvironment that was responsible for the up-regulation of ezrin. The identification of PTHrP and ezrin as important regulators of lung cancer bone metastasis offers new mechanistic insights into the metastasis of lung cancer and provides potential targets for the prevention and treatment of lung cancer metastasis.
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Affiliation(s)
- Xiyun Deng
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA
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25
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Li M, Green PL. Detection and quantitation of HTLV-1 and HTLV-2 mRNA species by real-time RT-PCR. J Virol Methods 2007; 142:159-68. [PMID: 17337070 PMCID: PMC2048902 DOI: 10.1016/j.jviromet.2007.01.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Revised: 01/18/2007] [Accepted: 01/26/2007] [Indexed: 11/17/2022]
Abstract
HTLV-1 and HTLV-2 are highly related delta-retroviruses that infect and transform T-lymphocytes, but have distinct pathogenic properties. HTLV replication and survival requires the expression of multiple gene products from an unspliced and a series of highly related alternatively spliced mRNA species. To date, the comparative levels of all known HTLV-1 and HTLV-2 viral mRNAs in different transformed cell lines and at different stages of virus infection have not been assessed. In this study, we compiled a series of oligonucleotide primer pairs and probes to quantify both HTLV-1 and HTLV-2 mRNA species using real-time RT-PCR. The optimized reaction for detection of each mRNA had amplification efficiency greater than 90% with a linear range spanning 25-2.5 x 10(7) copies. The R(2)'s of all standard curves were greater than 0.97. Quantitation of HTLV mRNAs between different cell lines showed variability (gag/pol>or=tax/rex>env>or=accessory proteins), but the overall levels of each mRNA relative to each other within a cell line were similar. These results provide a method to quantify all specific mRNAs from both HTLV-1 and HTLV-2, which can be used to evaluate further viral gene expression and correlate transcript levels to key stages of the virus life cycle and ultimately, pathogenesis.
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Affiliation(s)
- Min Li
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210
- Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210
- Ohio State Biochemistry Graduate Program, The Ohio State University, Columbus, OH 43210
| | - Patrick L. Green
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210
- Department of Molecular Virology Immunology and Medical Genetics, The Ohio State University, Columbus, OH 43210
- Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210
- Comprehensive Cancer Center and Solove Research Institute, The Ohio State University, Columbus, OH 43210
- Ohio State Biochemistry Graduate Program, The Ohio State University, Columbus, OH 43210
- * Corresponding Author: Patrick L. Green, The Ohio State University, 1925 Coffey Road, Columbus, OH 43210, Tel: (614)-688-4899, Fax: (614)-292-6473,
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26
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Nair AM, Michael B, Datta A, Fernandez S, Lairmore MD. Calcium-dependent enhancement of transcription of p300 by human T-lymphotropic type 1 p12I. Virology 2006; 353:247-57. [PMID: 16843515 PMCID: PMC3044894 DOI: 10.1016/j.virol.2006.06.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 02/10/2006] [Accepted: 06/06/2006] [Indexed: 10/24/2022]
Abstract
Human T-lymphotropic virus type 1 (HTLV-1) p12I localizes to the endoplasmic reticulum and Golgi causing sustained release of calcium, T cell activation, and enhanced expression of several calcium-regulated genes. In recent microarray studies, p300 mRNA was increased in T cells expressing p12I. The co-activator p300 is a key regulator of cellular and viral transcription; however, factors that influence its transcriptional regulation are less well studied. We hypothesized that the transcription of p300 is calcium dependent and that sustained low magnitude increases in intracellular calcium may enhance the transcription of p300. Herein, we report enhanced expression of p300 in T cells by p12I in a calcium-dependent, but calcineurin-independent manner. Sustained low magnitude calcium release induced by ionomycin in T cells was sufficient to increased mRNA and protein levels of p300 resulting in enhanced transcription from a p300-dependent promoter. Promoter analysis of the p300 gene was used to predict calcium-responsive transcription factor binding sites. Using mutant forms of p12I, we demonstrate that ER localization of the viral protein is required to increase p300. In addition, p12I reversed the repression of HTLV-1 LTR-driven transcription by HTLV-1 p30II, a p300-binding protein. HTLV-1 p12I-mediated enhancement of p300 expression represents a novel mechanism of regulation of cellular gene expression by viral proteins. By targeting a ubiquitous second messenger such as calcium, HTLV-1 p12I may regulate the expression of the cellular transcriptional co-activator p300 to modulate viral gene expression and promote lymphocyte survival.
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Affiliation(s)
- Amrithraj M. Nair
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA
| | - Bindhu Michael
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA
| | - Antara Datta
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA
- Ohio State Biochemistry Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Soledad Fernandez
- The Center for Statistics, College of Mathematical and Physical Sciences, The Ohio State University, Columbus, OH 43210, USA
| | - Michael D. Lairmore
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA
- Ohio State Biochemistry Graduate Program, The Ohio State University, Columbus, OH 43210, USA
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, OH 43210, USA
- Comprehensive Cancer Center, The Arthur G. James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Corresponding author. Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH 43210, USA. Fax: +1 614 292 6473, (M.D. Lairmore)
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Kim SJ, Nair AM, Fernandez S, Mathes L, Lairmore MD. Enhancement of LFA-1-mediated T cell adhesion by human T lymphotropic virus type 1 p12I1. THE JOURNAL OF IMMUNOLOGY 2006; 176:5463-70. [PMID: 16622014 PMCID: PMC2668115 DOI: 10.4049/jimmunol.176.9.5463] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cell-to-cell transmission of retroviruses, such as human T lymphotropic virus type 1 (HTLV-1), is well documented, but the roles of viral regulatory or other nonstructural proteins in the modulation of T cell adhesion are incompletely understood. In this study we tested the role of the HTLV-1 accessory protein, p12(I), on LFA-1-mediated cell adhesion. p12(I) is critical for early HTLV-1 infection by causing the release of calcium from the endoplasmic reticulum to activate NFAT-mediated transcription. We tested the role of this novel viral protein in mediating LFA-1-dependent cell adhesion. Our data indicated that T cells expressing a mutant HTLV-1 provirus that does not produce p12(I) mRNA (ACH.p12(I)) exhibited reduced LFA-1-mediated adhesion compared with wild-type HTLV-1-expressing cells (ACH). Furthermore, the expression of p12(I) in Jurkat T cells using lentiviral vectors enhanced LFA-1-mediated cell adhesion, which was inhibited by the calcium chelator BAPTA-AM, the calcium channel blocker SK&F 96365, and calpeptin, an inhibitor of the calcium-dependent protease calpain. Similar to the intracellular calcium mobilizer, thapsigargin, the expression of p12(I) in Jurkat T cells induced cell surface clustering of LFA-1 without changing the level of integrin expression. Our data are the first to indicate that HTLV-1 p12(I), in addition to enhancing T cell activation, promotes cell-to-cell spread by inducing LFA-1 clustering on T cells via calcium-dependent signaling.
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Affiliation(s)
- Seung-jae Kim
- Center for Retrovirus Research and Department of Veterinary Biosciences, Ohio State University, Columbus, OH 43210
| | - Amrithraj M. Nair
- Center for Retrovirus Research and Department of Veterinary Biosciences, Ohio State University, Columbus, OH 43210
| | | | - Lawrence Mathes
- Center for Retrovirus Research and Department of Veterinary Biosciences, Ohio State University, Columbus, OH 43210
- Comprehensive Cancer Center, The Arthur G. James Cancer Hospital and Solove Research Institute, Ohio State University, Columbus, OH 43210
- Department of Molecular Virology, Immunology, and Medical Genetics, Ohio State University, Columbus, OH 43210
| | - Michael D. Lairmore
- Center for Retrovirus Research and Department of Veterinary Biosciences, Ohio State University, Columbus, OH 43210
- Comprehensive Cancer Center, The Arthur G. James Cancer Hospital and Solove Research Institute, Ohio State University, Columbus, OH 43210
- Department of Molecular Virology, Immunology, and Medical Genetics, Ohio State University, Columbus, OH 43210
- Address correspondence and reprint requests to Dr. Michael D. Lairmore, Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH 43210-1093. E-mail address:
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Law PYP, Liu YM, Geng H, Kwan KH, Waye MMY, Ho YY. Expression and functional characterization of the putative protein 8b of the severe acute respiratory syndrome-associated coronavirus. FEBS Lett 2006; 580:3643-8. [PMID: 16753150 PMCID: PMC7094570 DOI: 10.1016/j.febslet.2006.05.051] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2006] [Accepted: 05/19/2006] [Indexed: 12/17/2022]
Abstract
SARS 8b is one of the putative accessory proteins of the severe acute respiratory syndrome‐associated coronavirus (SARS‐CoV) with unknown functions. In this study, the cellular localization and activity of this estimated 9.6 kDa protein were examined. Confocal microscopy results indicated that SARS 8b is localized in both nucleus and cytoplasm of mammalian cells. Functional study revealed that overexpression of SARS 8b induced DNA synthesis. Coexpression of SARS 8b and SARS 6, a previously characterized SARS‐CoV accessory protein, did not elicit synergistic effects on DNA synthesis.
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Affiliation(s)
- Pui Ying Peggy Law
- The Department of Biochemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
| | - Yuet-Man Liu
- The Department of Biochemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
| | - Hua Geng
- The Department of Biochemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
| | - Ka Ho Kwan
- The Molecular Biotechnology Program, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Mary Miu-Yee Waye
- The Department of Biochemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
- Croucher Laboratory for Human Genomics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Yuan-Yuan Ho
- The Department of Biochemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
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29
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Abstract
Human T-lymphotropic virus type 1 (HTLV-1) infection is associated with the clonal expansion and transformation of mature T lymphocytes. While the mechanisms involved are incompletely understood the viral regulatory protein Tax plays a central role in these processes. Recent studies employing genomic and proteomic approaches have demonstrated the marked complexity of gene deregulation associated with Tax expression and confirmed the remarkable pleiotropism of this protein as evidenced by the numerous Tax-cellular protein interactions in infected cells. In this review, we summarize the role of Tax in the deregulation of selected cellular-signaling pathways. Specifically, this has focused on the influence and interaction of Tax with the AP-1 and NF-AT transcription factors, PDZ domain-containing proteins, Rho-GTPases, and the Janus kinase/signal transducer and activator of transcription and transforming growth factor-beta-signaling pathways. In addition to identifying the deregulation of events within these pathways, attempts have been made to highlight differences between HTLV-1 and -2, which may relate to differences in their pathogenic properties.
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Affiliation(s)
- William W Hall
- Department of Medical Microbiology, Centre for Research in Infectious Diseases, University College Dublin, Belfield, Dublin 4, Ireland.
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Hiraragi H, Michael B, Nair A, Silic-Benussi M, Ciminale V, Lairmore M. Human T-lymphotropic virus type 1 mitochondrion-localizing protein p13II sensitizes Jurkat T cells to Ras-mediated apoptosis. J Virol 2005; 79:9449-57. [PMID: 16014908 PMCID: PMC1181595 DOI: 10.1128/jvi.79.15.9449-9457.2005] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Human T-lymphotropic virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia. In addition to typical retroviral structural and enzymatic gene products, HTLV-1 encodes unique regulatory and accessory proteins, including a singly spliced pX open reading frame II (ORF II) product, p13(II). We have demonstrated that proviral clones of HTLV-1 which are mutated in pX ORF II fail to obtain typical proviral loads and antibody responses in a rabbit animal model. p13(II) localizes to mitochondria and reduces cell growth and tumorigenicity in mice, but its function in human lymphocytes remains undetermined. For this study, we analyzed the functional properties of Jurkat T cells expressing p13(II), using both transient and stable expression vectors. Our data indicate that p13(II)-expressing Jurkat T cells are sensitive to caspase-dependent, ceramide- and FasL-induced apoptosis. p13(II)-expressing Jurkat T cells also exhibited reduced proliferation when cultured at a high density. Furthermore, preincubation of the p13(II)-expressing cells with a farnesyl transferase inhibitor, which blocks the posttranslational modification of Ras, markedly reduced FasL-induced apoptosis, indicating the participation of the Ras pathway in p13(II)'s influence on lymphocyte survival. Our data are the first to demonstrate that p13(II) alters Ras-mediated apoptosis in T lymphocytes, and they reveal a potential mechanism by which HTLV-1 alters lymphocyte proliferation.
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Affiliation(s)
- Hajime Hiraragi
- Center for Retrovirus Research and Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, 43210, USA
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Nair A, Michael B, Hiraragi H, Fernandez S, Feuer G, Boris-Lawrie K, Lairmore M. Human T lymphotropic virus type 1 accessory protein p12I modulates calcium-mediated cellular gene expression and enhances p300 expression in T lymphocytes. AIDS Res Hum Retroviruses 2005; 21:273-84. [PMID: 15943569 PMCID: PMC2668121 DOI: 10.1089/aid.2005.21.273] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Human T-lymphotropic virus type 1 (HTLV-1) is the etiologic agent of adult T cell leukemia/lymphoma (ATLL), an aggressive CD4+ T lymphocyte malignancy. Activation of T lymphocytes is required for effective retroviral integration into the host cell genome and subsequent viral replication, but the molecular mechanisms involved in HTLV-1-mediated T cell activation remain unclear. HTLV-1 encodes various accessory proteins such as p12I, which has been demonstrated to be critical for HTLV-1 infectivity in vivo in rabbits and in vitro in quiescent primary human T lymphocytes. This hydrophobic protein localizes in the endoplasmic reticulum, increases intracellular calcium, and activates nuclear factor of activated T cell-mediated transcription. To further elucidate the role of p12I in regulation of cellular gene expression, we performed gene array analysis on stable p12I-expressing Jurkat T cells, using Affymetrix U133A arrays. Our data indicate that p12I altered the expression of genes associated with a network of interrelated pathways including T cell signaling, cell proliferation, and apoptosis. Expression of several calcium-regulated genes was found to be altered by p12I, consistent with known properties of the viral protein. Gene array findings were confirmed by semiquantitative RT-PCR in Jurkat T cells and primary CD4+ T lymphocytes. Furthermore, dose-dependent expression of p12I in Jurkat T cells resulted in significant increases in p300 and p300-dependent transcription. This is the first report of a viral protein influencing the transcription of p300, a rate-limiting coadapter critical in HTLV-1-mediated T cell activation. Collectively, our data strongly indicate that HTLV-1 p12I modulates cellular gene expression patterns to hasten the activation of T lymphocytes and thereby promote efficient viral infection.
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Affiliation(s)
- Amrithraj Nair
- Center for Retrovirus Research and Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio 43210, USA
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Abstract
Epidemiological studies have demonstrated that the relative percentage of malignant lymphoid proliferations varies widely according to geographical location and ethnic populations. HTLV-I is the etiological agent of adult T-cell leukemia/lymphoma (ATLL) and is also associated with cutaneous T-cell lymphoma (CTCL). However, a definite role of HTLV-I in mycosis fungoides (MF) and/or Sezary syndrome (SS) remains controversial. While most HTLV-I-infected individuals remain asymptomatic carriers, 1-5% will develop ATLL, an invariably fatal expansion of virus-infected CD4+ T cells. This low incidence and the long latency period preceding occurrence of the disease suggest that additional factors are involved in development of ATLL. In this review, diagnosis, clinical features, and molecular pathogenesis of HTLV-I are discussed.
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Affiliation(s)
- Christophe Nicot
- Department of Microbiology, Immunology and Molecular Genetics, University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
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Abstract
The pathogenesis of human T-cell leukemia virus (HTLV)-induced adult T-cell leukemia-lymphoma (ATLL) was explored using an infectious molecular viral clone and a transgenic mouse model. Activation of nuclear factor-kappaB by the HTLV transcriptional transactivator protein Tax was found to be important for lymphocyte immortalization and tumorigenesis. Interferon-gamma regulates tumor development owing primarily to angiostatic effects. Translational clinical studies of chemotherapy, interferon-alpha, and nucleoside reverse transcriptase inhibitors have also assisted in identifying the pathogenic features of ATLL.
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Affiliation(s)
- Lee Ratner
- Division of Molecular Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Quintana A, Griesemer D, Schwarz EC, Hoth M. Calcium-dependent activation of T-lymphocytes. Pflugers Arch 2004; 450:1-12. [PMID: 15806400 DOI: 10.1007/s00424-004-1364-4] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Accepted: 10/18/2004] [Indexed: 12/11/2022]
Abstract
Activation of T-lymphocytes requires stimulation of T-cell receptors (TCR) and co-stimulatory signals. Among different signalling cascades, TCR engagement induces Ca(2+) entry through plasma membrane Ca(2+) channels, which is an indispensable step for T-cells to expand clonally and to acquire effector functions. The Ca(2+) channels are activated by depletion of Ca(2+) stores and are called Ca(2+) release-activated Ca(2+) (CRAC) channels. Ca(2+) influx through CRAC channels is also controlled, directly or indirectly, by K(+) channels, Ca(2+)-ATPases, mitochondria, endoplasmic reticulum and Ca(2+) buffers. We review the functional implications of these transporters, organelles and buffers and develop a model of Ca(2+) signal generation that depends mainly on their relative mutual localization. This model offers the possibility of controlling amplitude and kinetics of Ca(2+) signals in T-cells. Decoding of various Ca(2+) signals allows differential activation of the transcription factor families nuclear factor of activated T-cells (NFAT), nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1). Variation of amplitude and kinetics of Ca(2+) signals thus is an important mechanism for modulating the specificity of T-cell responses.
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Affiliation(s)
- Ariel Quintana
- Institut für Physiologie, Universität des Saarlandes, Gebäude 58, 66421 Homburg/Saar, Germany
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Michael B, Nair AM, Hiraragi H, Shen L, Feuer G, Boris-Lawrie K, Lairmore MD. Human T lymphotropic virus type-1 p30II alters cellular gene expression to selectively enhance signaling pathways that activate T lymphocytes. Retrovirology 2004; 1:39. [PMID: 15560845 PMCID: PMC538277 DOI: 10.1186/1742-4690-1-39] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2004] [Accepted: 11/23/2004] [Indexed: 11/13/2022] Open
Abstract
Background Human T-lymphotropic virus type-1 (HTLV-1) is a deltaretrovirus that causes adult T-cell leukemia/lymphoma and is implicated in a variety of lymphocyte-mediated disorders. HTLV-1 contains both regulatory and accessory genes in four pX open reading frames. pX ORF-II encodes two proteins, p13II and p30II, which are incompletely defined in the virus life cycle or HTLV-1 pathogenesis. Proviral clones of the virus with pX ORF-II mutations diminish the ability of the virus to maintain viral loads in vivo. Exogenous expression of p30II differentially modulates CREB and Tax-responsive element-mediated transcription through its interaction with CREB-binding protein/p300 and represses tax/rex RNA nuclear export. Results Herein, we further characterized the role of p30II in regulation of cellular gene expression, using stable p30II expression system employing lentiviral vectors to test cellular gene expression with Affymetrix U133A arrays, representing ~33,000 human genes. Reporter assays in Jurkat T cells and RT-PCR in Jurkat and primary CD4+ T-lymphocytes were used to confirm selected gene expression patterns. Our data reveals alterations of interrelated pathways of cell proliferation, T-cell signaling, apoptosis and cell cycle in p30II expressing Jurkat T cells. In all categories, p30II appeared to be an overall repressor of cellular gene expression, while selectively increasing the expression of certain key regulatory genes. Conclusions We are the first to demonstrate that p30II, while repressing the expression of many genes, selectively activates key gene pathways involved in T-cell signaling/activation. Collectively, our data suggests that this complex retrovirus, associated with lymphoproliferative diseases, relies upon accessory gene products to modify cellular environment to promote clonal expansion of the virus genome and thus maintain proviral loads in vivo.
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Affiliation(s)
- Bindhu Michael
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Safety Assessment, Merck &Co., Inc. WP45-224, West Point PA 19486, USA
| | - Amrithraj M Nair
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Safety Assessment, Merck &Co., Inc. WP45-224, West Point PA 19486, USA
| | - Hajime Hiraragi
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210, USA
| | - Lei Shen
- Department of Statistics, College of Mathematical and Physical Sciences, The Ohio State University, Columbus, Ohio 43210, USA
| | - Gerold Feuer
- Department of Microbiology and Immunology, State University of New York Upstate Medical University, Syracuse, New York 13210, USA
| | - Kathleen Boris-Lawrie
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, Ohio 43210, USA
- Comprehensive Cancer Center, The Arthur G. James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, Ohio 43210, USA
| | - Michael D Lairmore
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, Ohio 43210, USA
- Comprehensive Cancer Center, The Arthur G. James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, Ohio 43210, USA
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Debacq C, Sanchez Alcaraz MT, Mortreux F, Kerkhofs P, Kettmann R, Willems L. Reduced proviral loads during primo-infection of sheep by Bovine Leukemia virus attenuated mutants. Retrovirology 2004; 1:31. [PMID: 15462678 PMCID: PMC526217 DOI: 10.1186/1742-4690-1-31] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2004] [Accepted: 10/05/2004] [Indexed: 11/23/2022] Open
Abstract
Background The early stages consecutive to infection of sheep (e.g. primo-infection) by Bovine leukemia virus mutants are largely unknown. In order to better understand the mechanisms associated with this period, we aimed at analyzing simultaneously three parameters: B-lymphocytosis, cell proliferation and viral replication. Results Sheep were experimentally infected either with a wild type BLV provirus or with selected mutants among which: a virus harboring an optimalized LTR promoter with consensus cyclic AMP-responsive elements, two deletants of the R3 or the G4 accessory genes and a fusion-deficient transmembrane recombinant. Seroconversion, as revealed by the onset of an anti-viral antibody response, was detected at 3 to 11 weeks after inoculation. At seroconversion, all sheep exhibited a marked increase in the numbers of circulating B lymphocytes expressing the CD5 and CD11b cluster of differentiation markers and, interestingly, this phenomenon occurred independently of the type of virus. The net increase of the absolute number of B cells was at least partially due to accelerated proliferation as revealed, after intravenous injection of bromodeoxyuridine, by the higher proportion of circulating BrdU+ B lymphocytes. BLV proviral DNA was detected by polymerase chain reaction in the leucocytes of all sheep, as expected. However, at seroconversion, the proviral loads were lower in sheep infected by the attenuated proviruses despite similar levels of B cell lymphocytosis. Conclusions We conclude that the proviral loads are not directly linked to the extent of B cell proliferation observed during primo-infection of BLV-infected sheep. We propose a model of opportunistic replication of the virus supported by a general activation process of B lymphocytes.
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Affiliation(s)
| | | | - Franck Mortreux
- Unité d'Oncogenèse Virale, CNRS UMR5537, Centre Léon Bérard, Lyon, France
| | - Pierre Kerkhofs
- Department of Virology, Veterinary and Agrochemical Research Centre, Uccle, Belgium
| | | | - Luc Willems
- Molecular and cellular biology, FUSAGx, Gembloux, Belgium
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Michael B, Nair A, Lairmore MD. Role of accessory proteins of HTLV-1 in viral replication, T cell activation, and cellular gene expression. FRONT BIOSCI-LANDMRK 2004; 9:2556-76. [PMID: 15358581 PMCID: PMC2829751 DOI: 10.2741/1417] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Human T-cell lymphotropic virus type 1 (HTLV-1), causes adult T cell leukemia/lymphoma (ATLL), and initiates a variety of immune mediated disorders. The viral genome encodes common structural and enzymatic proteins characteristic of all retroviruses and utilizes alternative splicing and alternate codon usage to make several regulatory and accessory proteins encoded in the pX region (pX ORF I to IV). Recent studies indicate that the accessory proteins p12I, p27I, p13II, and p30II, encoded by pX ORF I and II, contribute to viral replication and the ability of the virus to maintain typical in vivo expression levels. Proviral clones that are mutated in either pX ORF I or II, while fully competent in cell culture, are severely limited in their replicative capacity in a rabbit model. These HTLV-1 accessory proteins are critical for establishment of viral infectivity, enhance T-lymphocyte activation and potentially alter gene transcription and mitochondrial function. HTLV-1 pX ORF I expression is critical to the viral infectivity in resting primary lymphocytes suggesting a role for the calcineurin-binding protein p12I in lymphocyte activation. The endoplasmic reticulum and cis-Golgi localizing p12I activates NFAT, a key T cell transcription factor, through calcium-mediated signaling pathways and may lower the threshold of lymphocyte activation via the JAK/STAT pathway. In contrast p30II localizes to the nucleus and represses viral promoter activity, but may regulate cellular gene expression through p300/CBP or related co-activators of transcription. The mitochondrial localizing p13II induces morphologic changes in the organelle and may influence energy metabolism infected cells. Future studies of the molecular details HTLV-1 "accessory" proteins interactions will provide important new directions for investigations of HTLV-1 and related viruses associated with lymphoproliferative diseases. Thus, the accessory proteins of HTLV-1, once thought to be dispensable for viral replication, have proven to be directly involved in viral spread in vivo and represent potential targets for therapeutic intervention against HTLV-1 infection and disease.
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Affiliation(s)
- Bindhu Michael
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210
| | - Amithraj Nair
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210
| | - Michael D. Lairmore
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, Ohio 43210
- Comprehensive Cancer Center, The Arthur G. James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, Ohio 43210
- Corresponding Author: Dr. Michael D. Lairmore, The Ohio State University, Department of Veterinary Biosciences, 1925 Coffey Road, Columbus, OH 43210-1093, Phone: (614) 292-4489. Fax: (614) 292-6473.
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