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Nakamura-Hoshi M, Ishii H, Nomura T, Nishizawa M, Hau TTT, Kuse N, Okazaki M, Ainai A, Suzuki T, Hasegawa H, Yoshida T, Yonemitsu K, Suzaki Y, Ami Y, Yamamoto H, Matano T. Prophylactic vaccination inducing anti-Env antibodies can result in protection against HTLV-1 challenge in macaques. Mol Ther 2024; 32:2328-2339. [PMID: 38734900 PMCID: PMC11286815 DOI: 10.1016/j.ymthe.2024.05.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 04/21/2024] [Accepted: 05/09/2024] [Indexed: 05/13/2024] Open
Abstract
Human T cell leukemia/T-lymphotropic virus type 1 (HTLV-1) infection occurs by cell-to-cell transmission and can induce fatal adult T cell leukemia. Vaccine development is critical for the control of HTLV-1 transmission. However, determining whether vaccine-induced anti-Env antibodies can prevent cell-to-cell HTLV-1 transmission is challenging. Here, we examined the protective efficacy of a vaccine inducing anti-Env antibodies against HTLV-1 challenge in cynomolgus macaques. Eight of 10 vaccinated macaques produced anti-HTLV-1 neutralizing antibodies (NAbs) and were protected from an intravenous challenge with 108 HTLV-1-producing cells. In contrast, the 2 vaccinated macaques without NAb induction and 10 unvaccinated controls showed HTLV-1 infection with detectable proviral load after challenge. Five of the eight protected macaques were administered with an anti-CD8 monoclonal antibody, but proviruses remained undetectable and no increase in anti-HTLV-1 antibodies was observed even after CD8+ cell depletion in three of them. Analysis of Env-specific T cell responses did not suggest involvement of vaccine-induced Env-specific T cell responses in the protection. These results indicate that anti-Env antibody induction by vaccination can result in functionally sterile HTLV-1 protection, implying the rationale for strategies aimed at anti-Env antibody induction in prophylactic HTLV-1 vaccine development.
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Affiliation(s)
- Midori Nakamura-Hoshi
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Hiroshi Ishii
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Takushi Nomura
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan; Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto 860-0811, Japan
| | - Masako Nishizawa
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Trang Thi Thu Hau
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Nozomi Kuse
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan; Research Center for Drug and Vaccine Development, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Midori Okazaki
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Akira Ainai
- Department of Pathology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Tadaki Suzuki
- Department of Pathology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Hideki Hasegawa
- Center for Influenza and Respiratory Virus Research, National Institute of Infectious Diseases, Tokyo 208-0011, Japan
| | - Takeshi Yoshida
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan; Management Department of Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo 208-0011, Japan
| | - Kenzo Yonemitsu
- Management Department of Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo 208-0011, Japan
| | - Yuriko Suzaki
- Management Department of Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo 208-0011, Japan
| | - Yasushi Ami
- Management Department of Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo 208-0011, Japan
| | - Hiroyuki Yamamoto
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan; Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto 860-0811, Japan; Department of Biomedicine, University Hospital Basel, 4031 Basel, Switzerland
| | - Tetsuro Matano
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan; Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto 860-0811, Japan; Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan.
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Gutowska A, Sarkis S, Rahman MA, Goldfarbmuren KC, Moles R, Bissa M, Doster M, Washington-Parks R, McKinnon K, Silva de Castro I, Schifanella L, Franchini G, Pise-Masison CA. Complete Rescue of HTLV-1 p12KO Infectivity by Depletion of Monocytes Together with NK and CD8 + T Cells. Pathogens 2024; 13:292. [PMID: 38668247 PMCID: PMC11054408 DOI: 10.3390/pathogens13040292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 03/25/2024] [Accepted: 03/28/2024] [Indexed: 04/29/2024] Open
Abstract
The transient depletion of monocytes alone prior to exposure of macaques to HTLV-1 enhances both HTLV-1WT (wild type) and HTLV-1p12KO (Orf-1 knockout) infectivity, but seroconversion to either virus is not sustained over time, suggesting a progressive decrease in virus expression. These results raise the hypotheses that either HTLV-1 persistence depends on a monocyte reservoir or monocyte depletion provides a transient immune evasion benefit. To test these hypotheses, we simultaneously depleted NK cells, CD8+ T cells, and monocytes (triple depletion) prior to exposure to HTLV-1WT or HTLV-1p12KO. Remarkably, triple depletion resulted in exacerbation of infection by both viruses and complete rescue of HTLV-1p12KO infectivity. Following triple depletion, we observed rapid and sustained seroconversion, high titers of antibodies against HTLV-1 p24Gag, and frequent detection of viral DNA in the blood and tissues of all animals when compared with depletion of only CD8+ and NK cells, or monocytes alone. The infection of macaques with HTLV-1WT or HTLV-1p12KO was associated with higher plasma levels of IL-10 after 21 weeks, while IL-6, IFN-γ, IL-18, and IL-1β were only elevated in animals infected with HTLV-1WT. The repeat depletion of monocytes, NK, and CD8+ cells seven months following the first exposure to HTLV-1 did not further exacerbate viral replication. These results underscore the contribution of monocytes in orchestrating anti-viral immunity. Indeed, the absence of orf-1 expression was fully compensated by the simultaneous depletion of CD8+ T cells, NK cells, and monocytes, underlining the primary role of orf-1 in hijacking host immunity.
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Affiliation(s)
- Anna Gutowska
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA; (A.G.); (S.S.); (I.S.d.C.)
| | - Sarkis Sarkis
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA; (A.G.); (S.S.); (I.S.d.C.)
| | - Mohammad Arif Rahman
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA; (A.G.); (S.S.); (I.S.d.C.)
| | - Katherine C. Goldfarbmuren
- Vaccine Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA;
- Advanced Biomedical Computational Science, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702, USA
| | - Ramona Moles
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA; (A.G.); (S.S.); (I.S.d.C.)
| | - Massimiliano Bissa
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA; (A.G.); (S.S.); (I.S.d.C.)
| | - Melvin Doster
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA; (A.G.); (S.S.); (I.S.d.C.)
| | - Robyn Washington-Parks
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA; (A.G.); (S.S.); (I.S.d.C.)
| | - Katherine McKinnon
- Vaccine Branch Flow Cytometry Core, National Cancer Institute, Bethesda, MD 20892, USA;
| | - Isabela Silva de Castro
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA; (A.G.); (S.S.); (I.S.d.C.)
| | - Luca Schifanella
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA; (A.G.); (S.S.); (I.S.d.C.)
| | - Genoveffa Franchini
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA; (A.G.); (S.S.); (I.S.d.C.)
| | - Cynthia A. Pise-Masison
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA; (A.G.); (S.S.); (I.S.d.C.)
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Nakamura-Hoshi M, Nomura T, Nishizawa M, Hau TTT, Yamamoto H, Okazaki M, Ishii H, Yonemitsu K, Suzaki Y, Ami Y, Matano T. HTLV-1 Proliferation after CD8 + Cell Depletion by Monoclonal Anti-CD8 Antibody Administration in Latently HTLV-1-Infected Cynomolgus Macaques. Microbiol Spectr 2023; 11:e0151823. [PMID: 37367230 PMCID: PMC10434050 DOI: 10.1128/spectrum.01518-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 06/08/2023] [Indexed: 06/28/2023] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) induces chronic asymptomatic latent infection with a substantial proviral load but without significant viral replication in vivo. Cumulative studies have indicated involvement of CD8-positive (CD8+) cells, including virus-specific CD8+ T cells in the control of HTLV-1 replication. However, whether HTLV-1 expression from latently infected cells in vivo occurs in the absence of CD8+ cells remains unclear. Here, we examined the impact of CD8+ cell depletion by monoclonal anti-CD8 antibody administration on proviral load in HTLV-1-infected cynomolgus macaques. Five cynomolgus macaques were infected with HTLV-1 by inoculation with HTLV-1-producing cells. Administration of monoclonal anti-CD8 antibody in the chronic phase resulted in complete depletion of peripheral CD8+ T cells for approximately 2 months. All five macaques showed an increase in proviral load following CD8+ cell depletion, which peaked just before the reappearance of peripheral CD8+ T cells. Tax-specific CD8+ T-cell responses were detected in these recovered CD8+ T cells. Importantly, anti-HTLV-1 antibodies also increased after CD8+ cell depletion, indicating HTLV-1 antigen expression. These results provide evidence indicating that HTLV-1 can proliferate from the latent phase in the absence of CD8+ cells and suggest that CD8+ cells are responsible for the control of HTLV-1 replication. IMPORTANCE HTLV-1 can cause serious diseases such as adult T-cell leukemia (ATL) in humans after chronic asymptomatic latent infection with substantial proviral load. Proviruses are detectable in peripheral lymphocytes in HTLV-1 carriers, and the association of a higher proviral load with a higher risk of disease progression has been observed. However, neither substantial viral structural protein expression nor viral replication was detectable in vivo. Cumulative studies have indicated involvement of CD8+ cells, including virus-specific CD8+ T cells in the control of HTLV-1 replication. In the present study, we showed that CD8+ cell depletion by monoclonal anti-CD8 antibody administration results in HTLV-1 expression and an increase in proviral load in HTLV-1-infected cynomolgus macaques. Our results indicate that HTLV-1 can proliferate in the absence of CD8+ cells, suggesting that CD8+ cells are responsible for the control of HTLV-1 replication. This study provides insights into the mechanism of virus-host immune interaction in latent HTLV-1 infection.
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Affiliation(s)
| | - Takushi Nomura
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
- Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
| | - Masako Nishizawa
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Trang Thi Thu Hau
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Hiroyuki Yamamoto
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Midori Okazaki
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Hiroshi Ishii
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kenzo Yonemitsu
- Management Department of Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yuriko Suzaki
- Management Department of Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yasushi Ami
- Management Department of Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tetsuro Matano
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
- Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
- Institute of Medical Science, University of Tokyo, Tokyo, Japan
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Pise-Masison CA, Franchini G. Hijacking Host Immunity by the Human T-Cell Leukemia Virus Type-1: Implications for Therapeutic and Preventive Vaccines. Viruses 2022; 14:2084. [PMID: 36298639 PMCID: PMC9609126 DOI: 10.3390/v14102084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/15/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2024] Open
Abstract
Human T-cell Leukemia virus type-1 (HTLV-1) causes adult T-cell leukemia/lymphoma (ATLL), HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and other inflammatory diseases. High viral DNA burden (VL) in peripheral blood mononuclear cells is a documented risk factor for ATLL and HAM/TSP, and patients with HAM/TSP have a higher VL in cerebrospinal fluid than in peripheral blood. VL alone is not sufficient to differentiate symptomatic patients from healthy carriers, suggesting the importance of other factors, including host immune response. HTLV-1 infection is life-long; CD4+-infected cells are not eradicated by the immune response because HTLV-1 inhibits the function of dendritic cells, monocytes, Natural Killer cells, and adaptive cytotoxic CD8+ responses. Although the majority of infected CD4+ T-cells adopt a resting phenotype, antigen stimulation may result in bursts of viral expression. The antigen-dependent "on-off" viral expression creates "conditional latency" that when combined with ineffective host responses precludes virus eradication. Epidemiological and clinical data suggest that the continuous attempt of the host immunity to eliminate infected cells results in chronic immune activation that can be further exacerbated by co-morbidities, resulting in the development of severe disease. We review cell and animal model studies that uncovered mechanisms used by HTLV-1 to usurp and/or counteract host immunity.
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Affiliation(s)
- Cynthia A. Pise-Masison
- Animal Models and Retroviral Vaccines Section, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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Saito M, Tanaka R, Fujii H, Kodama A, Takahashi Y, Matsuzaki T, Takashima H, Tanaka Y. The neutralizing function of the anti-HTLV-1 antibody is essential in preventing in vivo transmission of HTLV-1 to human T cells in NOD-SCID/γcnull (NOG) mice. Retrovirology 2014; 11:74. [PMID: 25163482 PMCID: PMC4180130 DOI: 10.1186/s12977-014-0074-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Accepted: 08/13/2014] [Indexed: 02/06/2023] Open
Abstract
Background Human T-cell leukemia virus type 1 (HTLV-1) causes both neoplastic and inflammatory diseases, including adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Because these life-threatening and disabling diseases are not yet curable, it is important to prevent new HTLV-1 infections. Findings In this study, we have established a simple humanized mouse model of HTLV-1 infection for evaluating prophylactic and therapeutic interventions. In this model, HTLV-1-negative normal human peripheral blood mononuclear cells (PBMCs) are transplanted directly into the spleens of severely immunodeficient NOD-SCID/γcnull (NOG) mice, together with mitomycin-treated HTLV-1-producing T cells. Using this model, we tested the efficacy of monoclonal antibodies (mAbs) specific to HTLV-1 as well as human IgG isolated from HAM/TSP patients (HAM-IgG) in preventing HTLV-1-infection. One hour before and 24 h after transplantation of the human cells, each antibody sample was inoculated intraperitoneally. On day 14, human PBMCs isolated from the mouse spleens were tested for HTLV-1 infection. Whereas fresh CD4-positive and CD8-positive T cells isolated from untreated mice or mice treated with isotype control mAb, HTLV-1 non-neutralizing mAbs to envelope gp46, gag p19, and normal human IgG were all infected with HTLV-1; the mice treated with either HTLV-1 neutralizing anti-gp46 mAb or HAM-IgG did not become infected. Conclusions Our data indicate that the neutralizing function of the antibody, but not the antigen specificity, is essential for preventing the in vivo transmission of HTLV-1. The present animal model will also be useful for the in vivo evaluation of the efficacy of candidate molecules to be used as prophylactic and therapeutic intervention against HTLV-1 infection. Electronic supplementary material The online version of this article (doi:10.1186/s12977-014-0074-z) contains supplementary material, which is available to authorized users.
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Abstract
Since the isolation and discovery of human T-cell leukemia virus type 1 (HTLV-1) over 30 years ago, researchers have utilized animal models to study HTLV-1 transmission, viral persistence, virus-elicited immune responses, and HTLV-1-associated disease development (ATL, HAM/TSP). Non-human primates, rabbits, rats, and mice have all been used to help understand HTLV-1 biology and disease progression. Non-human primates offer a model system that is phylogenetically similar to humans for examining viral persistence. Viral transmission, persistence, and immune responses have been widely studied using New Zealand White rabbits. The advent of molecular clones of HTLV-1 has offered the opportunity to assess the importance of various viral genes in rabbits, non-human primates, and mice. Additionally, over-expression of viral genes using transgenic mice has helped uncover the importance of Tax and Hbz in the induction of lymphoma and other lymphocyte-mediated diseases. HTLV-1 inoculation of certain strains of rats results in histopathological features and clinical symptoms similar to that of humans with HAM/TSP. Transplantation of certain types of ATL cell lines in immunocompromised mice results in lymphoma. Recently, “humanized” mice have been used to model ATL development for the first time. Not all HTLV-1 animal models develop disease and those that do vary in consistency depending on the type of monkey, strain of rat, or even type of ATL cell line used. However, the progress made using animal models cannot be understated as it has led to insights into the mechanisms regulating viral replication, viral persistence, disease development, and, most importantly, model systems to test disease treatments.
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Affiliation(s)
- Amanda R Panfil
- Center for Retrovirus Research, OH, USA. ; Department of Veterinary Biosciences, OH, USA
| | - Jacob J Al-Saleem
- Center for Retrovirus Research, OH, USA. ; Department of Veterinary Biosciences, OH, USA
| | - Patrick L Green
- Center for Retrovirus Research, OH, USA. ; Department of Veterinary Biosciences, OH, USA. ; Comprenhensive Cancer Center and Solove Research Institute, OH, USA. ; Department of Molecular Virology, Immunology, and Medical Genetics, The Ohio State University Columbus, OH, USA
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Lairmore MD, Silverman L, Ratner L. Animal models for human T-lymphotropic virus type 1 (HTLV-1) infection and transformation. Oncogene 2005; 24:6005-15. [PMID: 16155607 PMCID: PMC2652704 DOI: 10.1038/sj.onc.1208974] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Over the past 25 years, animal models of human T-lymphotropic virus type 1 (HTLV-1) infection and transformation have provided critical knowledge about viral and host factors in adult T-cell leukemia/lymphoma (ATL). The virus consistently infects rabbits, some non-human primates, and to a lesser extent rats. In addition to providing fundamental concepts in viral transmission and immune responses against HTLV-1 infection, these models have provided new information about the role of viral proteins in carcinogenesis. Mice and rats, in particular immunodeficient strains, are useful models to assess immunologic parameters mediating tumor outgrowth and therapeutic invention strategies against lymphoma. Genetically altered mice including both transgenic and knockout mice offer important models to test the role of specific viral and host genes in the development of HTLV-1-associated lymphoma. Novel approaches in genetic manipulation of both HTLV-1 and animal models are available to address the complex questions that remain about viral-mediated mechanisms of cell transformation and disease. Current progress in the understanding of the molecular events of HTLV-1 infection and transformation suggests that answers to these questions are approachable using animal models of HTLV-1-associated lymphoma.
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Affiliation(s)
- Michael D Lairmore
- Center for Retrovirus Research and Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210-1093, USA.
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Hadlock KG, Rowe J, Foung SK. The humoral immune response to human T-cell lymphotropic virus type 1 envelope glycoprotein gp46 is directed primarily against conformational epitopes. J Virol 1999; 73:1205-12. [PMID: 9882322 PMCID: PMC103941 DOI: 10.1128/jvi.73.2.1205-1212.1999] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Individuals infected with human T-cell lymphotropic virus type 1 (HTLV-1) develop a robust immune response to the surface envelope glycoprotein gp46 that is partially protective. The relative contribution of antibodies to conformation-dependent epitopes, including those mediating virus neutralization as part of the humoral immune response, is not well defined. We assess in this report the relationship between defined linear and conformational epitopes and the antibodies elicited to these domains. First, five monoclonal antibodies to linear epitopes within gp46 were evaluated for their ability to abrogate binding of three human monoclonal antibodies that inhibit HTLV-1-mediated syncytia formation and recognize conformational epitopes. Binding of antibodies to conformational epitopes was unaffected by antibodies to linear epitopes throughout the carboxy-terminal half and central domain of HTLV-1 gp46. Second, an enzyme-linked immunoadsorbent assay was developed and used to measure serum antibodies to native and denatured gp46 from HTLV-1-infected individuals. In sera from infected individuals, reactivity to denatured gp46 had an average of 15% of the reactivity observed to native gp46. Third, serum antibodies from 24 of 25 of HTLV-1-infected individuals inhibited binding of a neutralizing human monoclonal antibody, PRH-7A, to a conformational epitope on gp46 that is common to HTLV-1 and -2. Thus, antibodies to conformational epitopes comprise the majority of the immune response to HTLV-1 gp46, and the epitopes recognized by these antibodies do not appear to involve sequences in previously described immunodominant linear epitopes.
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Affiliation(s)
- K G Hadlock
- Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA.
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