1
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Malouli D, Gilbride RM, Wu HL, Hwang JM, Maier N, Hughes CM, Newhouse D, Morrow D, Ventura AB, Law L, Tisoncik-Go J, Whitmore L, Smith E, Golez I, Chang J, Reed JS, Waytashek C, Weber W, Taher H, Uebelhoer LS, Womack JL, McArdle MR, Gao J, Papen CR, Lifson JD, Burwitz BJ, Axthelm MK, Smedley J, Früh K, Gale M, Picker LJ, Hansen SG, Sacha JB. Cytomegalovirus-vaccine-induced unconventional T cell priming and control of SIV replication is conserved between primate species. Cell Host Microbe 2022; 30:1207-1218.e7. [PMID: 35981532 PMCID: PMC9927879 DOI: 10.1016/j.chom.2022.07.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 06/01/2022] [Accepted: 07/19/2022] [Indexed: 01/26/2023]
Abstract
Strain 68-1 rhesus cytomegalovirus expressing simian immunodeficiency virus (SIV) antigens (RhCMV/SIV) primes MHC-E-restricted CD8+ T cells that control SIV replication in 50%-60% of the vaccinated rhesus macaques. Whether this unconventional SIV-specific immunity and protection is unique to rhesus macaques or RhCMV or is intrinsic to CMV remains unknown. Here, using cynomolgus CMV vectors expressing SIV antigens (CyCMV/SIV) and Mauritian cynomolgus macaques, we demonstrate that the induction of MHC-E-restricted CD8+ T cells requires matching CMV to its host species. RhCMV does not elicit MHC-E-restricted CD8+ T cells in cynomolgus macaques. However, cynomolgus macaques vaccinated with species-matched 68-1-like CyCMV/SIV mounted MHC-E-restricted CD8+ T cells, and half of the vaccinees stringently controlled SIV post-challenge. Protected animals manifested a vaccine-induced IL-15 transcriptomic signature that is associated with efficacy in rhesus macaques. These findings demonstrate that the ability of species-matched CMV vectors to elicit MHC-E-restricted CD8+ T cells that are required for anti-SIV efficacy is conserved in nonhuman primates, and these data support the development of HCMV/HIV for a prophylactic HIV vaccine.
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Affiliation(s)
- Daniel Malouli
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Roxanne M Gilbride
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Helen L Wu
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Joseph M Hwang
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Nicholas Maier
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Colette M Hughes
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Daniel Newhouse
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA 98109, USA
| | - David Morrow
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Abigail B Ventura
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Lynn Law
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA 98109, USA
| | - Jennifer Tisoncik-Go
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA 98109, USA
| | - Leanne Whitmore
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA 98109, USA
| | - Elise Smith
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA 98109, USA
| | - Inah Golez
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA 98109, USA
| | - Jean Chang
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA 98109, USA
| | - Jason S Reed
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Courtney Waytashek
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Whitney Weber
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Husam Taher
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Luke S Uebelhoer
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Jennie L Womack
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Matthew R McArdle
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Junwei Gao
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Courtney R Papen
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Jeffrey D Lifson
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Benjamin J Burwitz
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Michael K Axthelm
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Jeremy Smedley
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Klaus Früh
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Michael Gale
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA 98109, USA
| | - Louis J Picker
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Scott G Hansen
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA.
| | - Jonah B Sacha
- Vaccine & Gene Therapy Institute, Oregon Health & Science University, Beaverton, OR 97006, USA; Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, 97006, USA.
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2
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Hau TTT, Nakamura-Hoshi M, Kanno Y, Nomura T, Nishizawa M, Seki S, Ishii H, Kawana-Tachikawa A, Hall WW, Nguyen Thi LA, Matano T, Yamamoto H. CD8 + T cell-based strong selective pressure on multiple simian immunodeficiency virus targets in macaques possessing a protective MHC class I haplotype. Biochem Biophys Res Commun 2019; 512:213-217. [PMID: 30878187 DOI: 10.1016/j.bbrc.2019.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Accepted: 03/01/2019] [Indexed: 10/27/2022]
Abstract
In human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections, host major histocompatibility complex class I (MHC-I) genotypes have a great impact on viral replication and MHC-I-associated viral genome mutations are selected under CD8+ T-cell pressure. Association of MHC-I genotypes with HIV/SIV control has been investigated at MHC-I allele levels but not fully at haplotype levels. We previously established groups of rhesus macaques sharing individual MHC-I haplotypes. In the present study, we compared viral genome diversification after SIV infection in macaques possessing a protective MHC-I haplotype, 90-010-Id, with those possessing a non-protective MHC-I haplotype, 90-010-Ie. These two MHC-I haplotypes are associated with immunodominant CD8+ T-cell responses targeting similar regions of viral Nef antigen. Analyses of viral genome sequences and antigen-specific T-cell responses showed four and two candidates of viral CD8+ T-cell targets associated with 90-010-Id and 90-010-Ie, respectively, in addition to the Nef targets. In these CD8+ T-cell target regions, higher numbers of mutations were detected at the setpoint after SIV infection in macaques possessing 90-010-Id than those possessing 90-010-Ie. These results indicate higher selective pressure on overall CD8+ T-cell targets associated with the protective MHC-I haplotype, suggesting a pattern of HIV/SIV control by multiple target-specific CD8+ T-cell responses.
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Affiliation(s)
- Trang Thi Thu Hau
- AIDS Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama City, Tokyo, 208-0011, Japan; Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Kumamoto, 860-0811, Japan; Center of BioMedical Research, National Institute of Hygiene and Epidemiology, No.1 Yersin Street, Hanoi, Viet Nam
| | - Midori Nakamura-Hoshi
- AIDS Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama City, Tokyo, 208-0011, Japan; The Institute of Medical Science/Graduate School of Medicine/Graduate School of Frontier Sciences, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo, 108-8639, Japan
| | - Yoshiaki Kanno
- AIDS Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama City, Tokyo, 208-0011, Japan; The Institute of Medical Science/Graduate School of Medicine/Graduate School of Frontier Sciences, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo, 108-8639, Japan
| | - Takushi Nomura
- AIDS Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama City, Tokyo, 208-0011, Japan
| | - Masako Nishizawa
- AIDS Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama City, Tokyo, 208-0011, Japan
| | - Sayuri Seki
- AIDS Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama City, Tokyo, 208-0011, Japan
| | - Hiroshi Ishii
- AIDS Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama City, Tokyo, 208-0011, Japan
| | - Ai Kawana-Tachikawa
- AIDS Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama City, Tokyo, 208-0011, Japan; Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Kumamoto, 860-0811, Japan; The Institute of Medical Science/Graduate School of Medicine/Graduate School of Frontier Sciences, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo, 108-8639, Japan
| | - William W Hall
- Center of BioMedical Research, National Institute of Hygiene and Epidemiology, No.1 Yersin Street, Hanoi, Viet Nam; Centre for Research in Infectious Diseases, School of Medicine & Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Lan Anh Nguyen Thi
- Center of BioMedical Research, National Institute of Hygiene and Epidemiology, No.1 Yersin Street, Hanoi, Viet Nam.
| | - Tetsuro Matano
- AIDS Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama City, Tokyo, 208-0011, Japan; Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Kumamoto, 860-0811, Japan; The Institute of Medical Science/Graduate School of Medicine/Graduate School of Frontier Sciences, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo, 108-8639, Japan.
| | - Hiroyuki Yamamoto
- AIDS Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-Murayama City, Tokyo, 208-0011, Japan.
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3
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Ishii H, Matsuoka S, Nomura T, Nakamura M, Shiino T, Sato Y, Iwata-Yoshikawa N, Hasegawa H, Mizuta K, Sakawaki H, Miura T, Koyanagi Y, Naruse TK, Kimura A, Matano T. Association of lymph-node antigens with lower Gag-specific central-memory and higher Env-specific effector-memory CD8(+) T-cell frequencies in a macaque AIDS model. Sci Rep 2016; 6:30153. [PMID: 27452272 PMCID: PMC4958968 DOI: 10.1038/srep30153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 06/27/2016] [Indexed: 01/17/2023] Open
Abstract
Virus-specific CD8+ T cells exert strong suppressive pressure on human/simian immunodeficiency virus (HIV/SIV) replication. These responses have been intensively examined in peripheral blood mononuclear cells (PBMCs) but not fully analyzed in lymph nodes (LNs), where interaction between CD8+ T cells and HIV/SIV-infected cells occurs. Here, we investigated target antigen specificity of CD8+ T cells in LNs in a macaque AIDS model. Analysis of virus antigen-specific CD8+ T-cell responses in the inguinal LNs obtained from twenty rhesus macaques in the chronic phase of SIV infection showed an inverse correlation between viral loads and frequencies of CD8+ T cells with CD28+ CD95+ central memory phenotype targeting the N-terminal half of SIV core antigen (Gag-N). In contrast, analysis of LNs but not PBMCs revealed a positive correlation between viral loads and frequencies of CD8+ T cells with CD28−CD95+ effector memory phenotype targeting the N-terminal half of SIV envelope (Env-N), soluble antigen. Indeed, LNs with detectable SIV capsid p27 antigen in the germinal center exhibited significantly lower Gag-N-specific CD28+ CD95+ CD8+ T-cell and higher Env-N-specific CD28−CD95+ CD8+ T-cell responses than those without detectable p27. These results imply that core and envelope antigen-specific CD8+ T cells show different patterns of interactions with HIV/SIV-infected cells.
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Affiliation(s)
- Hiroshi Ishii
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Saori Matsuoka
- 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.,Center for AIDS Research, Kumamoto University, Tokyo 162-8640, Japan
| | - Midori Nakamura
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Teiichiro Shiino
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Yuko Sato
- Department of Pathology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Naoko Iwata-Yoshikawa
- Department of Pathology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Hideki Hasegawa
- Department of Pathology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Kazuta Mizuta
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
| | - Hiromi Sakawaki
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
| | - Tomoyuki Miura
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
| | - Yoshio Koyanagi
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
| | - Taeko K Naruse
- Department of Molecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
| | - Akinori Kimura
- Department of Molecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
| | - Tetsuro Matano
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan.,The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
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4
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Martins MA, Tully DC, Cruz MA, Power KA, Veloso de Santana MG, Bean DJ, Ogilvie CB, Gadgil R, Lima NS, Magnani DM, Ejima K, Allison DB, Piatak M, Altman JD, Parks CL, Rakasz EG, Capuano S, Galler R, Bonaldo MC, Lifson JD, Allen TM, Watkins DI. Vaccine-Induced Simian Immunodeficiency Virus-Specific CD8+ T-Cell Responses Focused on a Single Nef Epitope Select for Escape Variants Shortly after Infection. J Virol 2015; 89:10802-20. [PMID: 26292326 PMCID: PMC4621113 DOI: 10.1128/jvi.01440-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 08/05/2015] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Certain major histocompatibility complex class I (MHC-I) alleles (e.g., HLA-B*27) are enriched among human immunodeficiency virus type 1 (HIV-1)-infected individuals who suppress viremia without treatment (termed "elite controllers" [ECs]). Likewise, Mamu-B*08 expression also predisposes rhesus macaques to control simian immunodeficiency virus (SIV) replication. Given the similarities between Mamu-B*08 and HLA-B*27, SIV-infected Mamu-B*08(+) animals provide a model to investigate HLA-B*27-mediated elite control. We have recently shown that vaccination with three immunodominant Mamu-B*08-restricted epitopes (Vif RL8, Vif RL9, and Nef RL10) increased the incidence of elite control in Mamu-B*08(+) macaques after challenge with the pathogenic SIVmac239 clone. Furthermore, a correlate analysis revealed that CD8(+) T cells targeting Nef RL10 was correlated with improved outcome. Interestingly, this epitope is conserved between SIV and HIV-1 and exhibits a delayed and atypical escape pattern. These features led us to postulate that a monotypic vaccine-induced Nef RL10-specific CD8(+) T-cell response would facilitate the development of elite control in Mamu-B*08(+) animals following repeated intrarectal challenges with SIVmac239. To test this, we vaccinated Mamu-B*08(+) animals with nef inserts in which Nef RL10 was either left intact (group 1) or disrupted by mutations (group 2). Although monkeys in both groups mounted Nef-specific cellular responses, only those in group 1 developed Nef RL10-specific CD8(+) T cells. These vaccine-induced effector memory CD8(+) T cells did not prevent infection. Escape variants emerged rapidly in the group 1 vaccinees, and ultimately, the numbers of ECs were similar in groups 1 and 2. High-frequency vaccine-induced CD8(+) T cells focused on a single conserved epitope and therefore did not prevent infection or increase the incidence of elite control in Mamu-B*08(+) macaques. IMPORTANCE Since elite control of chronic-phase viremia is a classic example of an effective immune response against HIV/SIV, elucidating the basis of this phenomenon may provide useful insights into how to elicit such responses by vaccination. We have previously established that vaccine-induced CD8(+) T-cell responses against three immunodominant epitopes can increase the incidence of elite control in SIV-infected Mamu-B*08(+) rhesus macaques—a model of HLA-B*27-mediated elite control. Here, we investigated whether a monotypic vaccine-induced CD8(+) T-cell response targeting the conserved "late-escaping" Nef RL10 epitope can increase the incidence of elite control in Mamu-B*08(+) monkeys. Surprisingly, vaccine-induced Nef RL10-specific CD8(+) T cells selected for variants within days after infection and, ultimately, did not facilitate the development of elite control. Elite control is, therefore, likely to involve CD8(+) T-cell responses against more than one epitope. Together, these results underscore the complexity and multidimensional nature of virologic control of lentivirus infection.
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Affiliation(s)
| | - Damien C Tully
- Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, USA
| | - Michael A Cruz
- Department of Pathology, University of Miami, Miami, Florida, USA
| | - Karen A Power
- Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, USA
| | | | - David J Bean
- Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, USA
| | - Colin B Ogilvie
- Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, USA
| | - Rujuta Gadgil
- Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, USA
| | - Noemia S Lima
- Laboratório de Biologia Molecular de Flavivirus, Instituto Oswaldo Cruz-FIOCRUZ, Rio de Janeiro, Brazil
| | - Diogo M Magnani
- Department of Pathology, University of Miami, Miami, Florida, USA
| | - Keisuke Ejima
- Section on Statistical Genetics, Department of Biostatistics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - David B Allison
- Section on Statistical Genetics, Department of Biostatistics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Michael Piatak
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, Maryland, USA
| | - John D Altman
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
| | - Christopher L Parks
- International AIDS Vaccine Initiative, AIDS Vaccine Design and Development Laboratory, Brooklyn Army Terminal, Brooklyn, New York, USA
| | - Eva G Rakasz
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Saverio Capuano
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Ricardo Galler
- Instituto de Tecnologia em Imunobiológicos, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Myrna C Bonaldo
- Laboratório de Biologia Molecular de Flavivirus, Instituto Oswaldo Cruz-FIOCRUZ, Rio de Janeiro, Brazil
| | - Jeffrey D Lifson
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, Maryland, USA
| | - Todd M Allen
- Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, USA
| | - David I Watkins
- Department of Pathology, University of Miami, Miami, Florida, USA
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5
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Ishii H, Matano T. Development of an AIDS vaccine using Sendai virus vectors. Vaccine 2015; 33:6061-5. [PMID: 26232346 DOI: 10.1016/j.vaccine.2015.06.114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Revised: 06/22/2015] [Accepted: 06/30/2015] [Indexed: 10/23/2022]
Abstract
Development of an effective AIDS vaccine is crucial for the control of global human immunodeficiency virus type 1 (HIV-1) prevalence. We have developed a novel AIDS vaccine using a Sendai virus (SeV) vector and investigated its efficacy in a macaque AIDS model of simian immunodeficiency virus (SIV) infection. Its immunogenicity and protective efficacy have been shown, indicating that the SeV vector is a promising delivery tool for AIDS vaccines. Here, we describe the potential of SeV vector as a vaccine antigen delivery tool to induce effective immune responses against HIV-1 infection.
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Affiliation(s)
- Hiroshi Ishii
- AIDS Research Center, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan
| | - Tetsuro Matano
- AIDS Research Center, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan; The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
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6
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Mendoza D, Migueles SA, Rood JE, Peterson B, Johnson S, Doria-Rose N, Schneider D, Rakasz E, Trivett MT, Trubey CM, Coalter V, Hallahan CW, Watkins D, Franchini G, Lifson JD, Connors M. Cytotoxic capacity of SIV-specific CD8(+) T cells against primary autologous targets correlates with immune control in SIV-infected rhesus macaques. PLoS Pathog 2013; 9:e1003195. [PMID: 23468632 PMCID: PMC3585127 DOI: 10.1371/journal.ppat.1003195] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 12/29/2012] [Indexed: 11/19/2022] Open
Abstract
Although the study of non-human primates has resulted in important advances for understanding HIV-specific immunity, a clear correlate of immune control over simian immunodeficiency virus (SIV) replication has not been found to date. In this study, CD8(+) T-cell cytotoxic capacity was examined to determine whether this function is a correlate of immune control in the rhesus macaque (RM) SIV infection model as has been suggested in chronic HIV infection. SIVmac251-infected human reverse transcriptase (hTERT)-transduced CD4(+) T-cell clone targets were co-incubated with autologous macaque effector cells to measure infected CD4(+) T-cell elimination (ICE). Twenty-three SIV-infected rhesus macaques with widely varying plasma viral RNA levels were evaluated in a blinded fashion. Nineteen of 23 subjects (83%) were correctly classified as long-term nonprogressor/elite controller (LTNP/EC), slow progressor, progressor or SIV-negative rhesus macaques based on measurements of ICE (weighted Kappa 0.75). LTNP/EC had higher median ICE than progressors (67.3% [22.0-91.7%] vs. 23.7% [0.0-58.0%], p = 0.002). In addition, significant correlations between ICE and viral load (r = -0.57, p = 0.01), and between granzyme B delivery and ICE (r = 0.89, p<0.001) were observed. Furthermore, the CD8(+) T cells of LTNP/EC exhibited higher per-cell cytotoxic capacity than those of progressors (p = 0.004). These findings support that greater lytic granule loading of virus-specific CD8(+) T cells and efficient delivery of active granzyme B to SIV-infected targets are associated with superior control of SIV infection in rhesus macaques, consistent with observations of HIV infection in humans. Therefore, such measurements appear to represent a correlate of control of viral replication in chronic SIV infection and their role as predictors of immunologic control in the vaccine setting should be evaluated.
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Affiliation(s)
- Daniel Mendoza
- HIV-Specific Immunity Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Stephen A. Migueles
- HIV-Specific Immunity Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Julia E. Rood
- HIV-Specific Immunity Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Bennett Peterson
- HIV-Specific Immunity Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Sarah Johnson
- HIV-Specific Immunity Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nicole Doria-Rose
- HIV-Specific Immunity Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Douglas Schneider
- AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Eva Rakasz
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Matthew T. Trivett
- AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Charles M. Trubey
- AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Vicky Coalter
- AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Claire W. Hallahan
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - David Watkins
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- University of Miami Miller School of Medicine, Department of Pathology Clinical Research Building, Miami, Florida, United States of America
| | - Genoveffa Franchini
- Vaccine Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jeffrey D. Lifson
- AIDS and Cancer Virus Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Mark Connors
- HIV-Specific Immunity Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
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7
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The majority of freshly sorted simian immunodeficiency virus (SIV)-specific CD8(+) T cells cannot suppress viral replication in SIV-infected macrophages. J Virol 2012; 86:4682-7. [PMID: 22318140 DOI: 10.1128/jvi.06324-11] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) primarily infect activated CD4(+) T cells but can infect macrophages. Surprisingly, ex vivo tetramer-sorted SIV-specific CD8(+) T cells that eliminated and suppressed viral replication in SIV-infected CD4(+) T cells failed to do so in SIV-infected macrophages. It is possible, therefore, that while AIDS virus-infected macrophages constitute only a small percentage of all virus-infected cells, they may be relatively resistant to CD8(+) T cell-mediated lysis and continue to produce virus over long periods of time.
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Plank C, Zelphati O, Mykhaylyk O. Magnetically enhanced nucleic acid delivery. Ten years of magnetofection-progress and prospects. Adv Drug Deliv Rev 2011; 63:1300-31. [PMID: 21893135 PMCID: PMC7103316 DOI: 10.1016/j.addr.2011.08.002] [Citation(s) in RCA: 251] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 08/18/2011] [Accepted: 08/19/2011] [Indexed: 12/28/2022]
Abstract
Nucleic acids carry the building plans of living systems. As such, they can be exploited to make cells produce a desired protein, or to shut down the expression of endogenous genes or even to repair defective genes. Hence, nucleic acids are unique substances for research and therapy. To exploit their potential, they need to be delivered into cells which can be a challenging task in many respects. During the last decade, nanomagnetic methods for delivering and targeting nucleic acids have been developed, methods which are often referred to as magnetofection. In this review we summarize the progress and achievements in this field of research. We discuss magnetic formulations of vectors for nucleic acid delivery and their characterization, mechanisms of magnetofection, and the application of magnetofection in viral and nonviral nucleic acid delivery in cell culture and in animal models. We summarize results that have been obtained with using magnetofection in basic research and in preclinical animal models. Finally, we describe some of our recent work and end with some conclusions and perspectives.
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Akinsiku OT, Bansal A, Sabbaj S, Heath SL, Goepfert PA. Interleukin-2 production by polyfunctional HIV-1-specific CD8 T cells is associated with enhanced viral suppression. J Acquir Immune Defic Syndr 2011; 58:132-40. [PMID: 21637109 PMCID: PMC3391567 DOI: 10.1097/qai.0b013e318224d2e9] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
BACKGROUND Assays to measure the induction of HIV-1-specific CD8 T-cell responses often rely on measurements of indirect effector function such as chemokine and cytokine production, which may not reflect direct elimination of an invading pathogen. Assessment of the functional ability of CD8 T cells to suppress HIV-1 replication has been viewed as a surrogate marker of an effectual immune response. To further investigate this, we measured the capacity of virus-specific CD8 T cells to inhibit HIV-1 replication in an in vitro suppression assay. METHODS We expanded 15 epitope-specific CD8 T-cell lines from peripheral blood mononuclear cells of chronically HIV--infected progressors (n = 5) and controllers (n = 4) who were not on antiretroviral therapy. Cell lines were tested for their ability to produce effector molecules (CD107a, IL-2, IFN-γ, TNF-α, perforin) and suppress virus replication in autologous CD4 T cells. RESULTS CD8 T-cell lines from both progressors and controllers had largely similar effector function profiles as determined by intracellular cytokine staining. In contrast, we observed that CD8 T-cell lines derived from controllers show enhanced virus suppression when compared with progressors. Virus suppression was mediated in an major histocompatibility complex-dependent manner and found to correlate with a polyfunctional IL-2 CD8 T-cell response. CONCLUSIONS Using a sensitive in vitro suppression assay, we demonstrate that CD8 T-cell-mediated suppression of HIV-1 replication is a marker of HIV-1 control. Suppressive capacity was found to correlate with polyfunctional IL-2 production. Assessment of CD8 T-cell-mediated suppression may be an important tool to evaluate vaccine-induced responses.
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Affiliation(s)
| | - Anju Bansal
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Steffanie Sabbaj
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Sonya L. Heath
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Paul A. Goepfert
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
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Makedonas G, Betts MR. Living in a house of cards: re-evaluating CD8+ T-cell immune correlates against HIV. Immunol Rev 2011; 239:109-24. [PMID: 21198668 DOI: 10.1111/j.1600-065x.2010.00968.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The Merck STEP and the Thai RV144 human immunodeficiency virus (HIV) vaccine trials confirmed that we still have a long way to go before developing a prophylactic HIV vaccine. The main issue at hand is that we have yet to identify an immunological correlate of protection against HIV. While many question the T-cell-based approach towards vaccine development, it is likely that T cells will be a necessary part of any vaccine strategy. CD8(+) T cells remain an attractive option because of their ability to specifically recognize and eliminate virally infected host cells. In this review, we recapitulate the evidence for CD8(+) T cells as an immunological correlate against HIV, but more importantly, we assess the means by which we evaluate their antiviral capacity. To achieve a breakthrough in the domain of T-cell-based HIV vaccine development, it has become abundantly clear that we must overhaul our system of immune monitoring and come up with a 'rational' tactic to evaluate the efficacy of HIV-specific CD8(+) T cells.
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Diverse peptide presentation of rhesus macaque major histocompatibility complex class I Mamu-A 02 revealed by two peptide complex structures and insights into immune escape of simian immunodeficiency virus. J Virol 2011; 85:7372-83. [PMID: 21561910 DOI: 10.1128/jvi.00350-11] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Major histocompatibility complex class I (MHC I)-restricted CD8(+) T-cell responses play a pivotal role in anti-human immunodeficiency virus (HIV) immunity and the control of viremia. The rhesus macaque is an important animal model for HIV-related research. Among the MHC I alleles of the rhesus macaque, Mamu-A 02 is prevalent, presenting in ≥20% of macaques. In this study, we determined the crystal structure of Mamu-A 02, the second structure-determined MHC I from the rhesus macaque after Mamu-A 01. The peptide presentation characteristics of Mamu-A 02 are exhibited in complex structures with two typical Mamu-A 02-restricted CD8(+) T-cell epitopes, YY9 (Nef159 to -167; YTSGPGIRY) and GY9 (Gag71 to -79; GSENLKSLY), derived from simian immunodeficiency virus (SIV). These two peptides utilize similar primary anchor residues (Ser or Thr) at position 2 and Tyr at position 9. However, the central region of YY9 is different from that of GY9, a difference that may correlate with the immunogenic variance of these peptides. Further analysis indicated that the distinct conformations of these two peptides are modulated by four flexible residues in the Mamu-A 02 peptide-binding groove. The rare combination of these four residues in Mamu-A 02 leads to a variant presentation for peptides with different residues in their central regions. Additionally, in the two structures of the Mamu-A 02 complex, we compared the binding of rhesus and human β(2) microglobulin (β(2)m) to Mamu-A 02. We found that the peptide presentation of Mamu-A 02 is not affected by the interspecies interaction with human β(2)m. Our work broadens the understanding of CD8(+) T-cell-specific immunity against SIV in the rhesus macaque.
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12
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Althaus CL, De Boer RJ. Implications of CTL-mediated killing of HIV-infected cells during the non-productive stage of infection. PLoS One 2011; 6:e16468. [PMID: 21326882 PMCID: PMC3034731 DOI: 10.1371/journal.pone.0016468] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 12/20/2010] [Indexed: 11/23/2022] Open
Abstract
Patients infected with HIV exhibit orders of magnitude differences in their set-point levels of the plasma viral load. As to what extent this variation is due to differences in the efficacy of the cytotoxic T lymphocyte (CTL) response in these patients is unclear. Several studies have shown that HIV-infected CD4+ T cells also present viral epitopes that are recognized by CTLs before the productive stage of infection, i.e., during the intracellular eclipse phase before the infected cell starts to produce new viral particles. Here, we use mathematical modeling to investigate the potential impact of early killing of HIV-infected cells on viral replication. We suggest that the majority of CTL-mediated killing could occur during the viral eclipse phase, and that the killing of virus-producing cells could be substantially lower at later stages due to MHC-I-down-regulation. Such a mechanism is in agreement with several experimental observations that include CD8+ T cell depletion and antiretroviral drug treatment. This indicates a potentially important role of CTL-mediated killing during the non-productive stage of HIV-infected cells.
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Antiviral activity of human immunodeficiency virus type 1 Gag-specific cytotoxic T lymphocyte targeting is not necessarily intrinsically superior to envelope targeting. J Virol 2010; 85:2474-8. [PMID: 21159882 DOI: 10.1128/jvi.01726-10] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Across several cohorts, human immunodeficiency virus type 1 (HIV-1) Gag- and Env-specific CD8(+) T lymphocyte (CTL) responses have demonstrated inverse and positive correlations, respectively, to viremia. The mechanism has been proposed to be superior antiviral activity of Gag-specific CTLs in general. Addressing this hypothesis, we created two HIV-1 constructs with an epitope translocated from Gag (SLYNTVATL, SL9) to Env, thereby switching the protein source of the epitope. A virus expressing SL9 in Env was similar to the original virus in susceptibility to SL9-specific CTLS. This finding suggests that Env targeting is not intrinsically inferior to Gag targeting for CTL antiviral activity.
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Chakrabarti LA, Simon V. Immune mechanisms of HIV control. Curr Opin Immunol 2010; 22:488-96. [PMID: 20650621 DOI: 10.1016/j.coi.2010.06.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 06/16/2010] [Accepted: 06/17/2010] [Indexed: 12/20/2022]
Abstract
HIV-1 can be contained by the immune system, as demonstrated by the existence of rare individuals who spontaneously control HIV-1 replication in the absence of antiretroviral therapy. Emerging evidence points to the importance of a very active cellular immune response in mediating HIV-1 control. The rapid induction of interferon-dependent HIV restriction factors, the presence of protective MHC class I alleles, and the development of a high avidity T-cell response may all cooperate in limiting HIV replication at an early stage. This review will focus on recent advances in understanding the immune mechanisms of HIV control, and on the lessons that may be drawn for the development of candidate HIV vaccines.
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Affiliation(s)
- Lisa A Chakrabarti
- Institut Pasteur, Unité d'Immunogénétique Cellulaire, 25 rue du Dr Roux, 75724 Paris Cedex 15, France.
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Simian immunodeficiency virus-specific CD8+ T cells recognize Vpr- and Rev-derived epitopes early after infection. J Virol 2010; 84:10907-12. [PMID: 20686015 DOI: 10.1128/jvi.01357-10] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The kinetics of CD8(+) T cell epitope presentation contribute to the antiviral efficacy of these cells yet remain poorly defined. Here, we demonstrate presentation of virion-derived Vpr peptide epitopes early after viral penetration and prior to presentation of Vif-derived epitopes, which required de novo Vif synthesis. Two Rev epitopes exhibited differential presentation kinetics, with one Rev epitope presented within 1 h of infection. We also demonstrate that cytolytic activity mirrors the recognition kinetics of infected cells. These studies show for the first time that Vpr- and Rev-specific CD8(+) T cells recognize and kill simian immunodeficiency virus (SIV)-infected CD4(+) T cells early after SIV infection.
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Ex vivo T cell-based HIV suppression assay to evaluate HIV-specific CD8+ T-cell responses. Nat Protoc 2010; 5:1033-41. [PMID: 20539279 DOI: 10.1038/nprot.2010.73] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
To advance T cell-based HIV vaccine development, it is necessary to evaluate the immune correlates of a protective CD8(+) T-cell response. We have developed an assay that assesses the capacity ex vivo of HIV-specific CD8(+) T cells to suppress HIV-1 infection of autologous CD4(+) T cells. This assay directly reflects the ultimate effector function of CD8(+) T cells, the elimination of infected cells, and accurately differentiates the effective CD8(+) T-cell response in spontaneous HIV controllers from ineffective responses in other patients. In this article, we describe all the steps from cell purification to assessment of viral replication by HIV-p24 ELISA and analysis, along with conditions for cell culturing, and how to choose the viral infectious dose that gives the most reliable results. We also depict the conditions of a rapid assay on the basis of flow cytometry analysis of intracellular HIV-Gag products. These procedures take 14-17 d when the p24 ELISA assay is used, or 6 d with the intracellular Gag assay.
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Recombinant yellow fever vaccine virus 17D expressing simian immunodeficiency virus SIVmac239 gag induces SIV-specific CD8+ T-cell responses in rhesus macaques. J Virol 2010; 84:3699-706. [PMID: 20089645 DOI: 10.1128/jvi.02255-09] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here we describe a novel vaccine vector for expressing human immunodeficiency virus (HIV) antigens. We show that recombinant attenuated yellow fever vaccine virus 17D expressing simian immunodeficiency virus SIVmac239 Gag sequences can be used as a vector to generate SIV-specific CD8(+) T-cell responses in the rhesus macaque. Priming with recombinant BCG expressing SIV antigens increased the frequency of these SIV-specific CD8(+) T-cell responses after recombinant YF17D boosting. These recombinant YF17D-induced SIV-specific CD8(+) T cells secreted several cytokines, were largely effector memory T cells, and suppressed viral replication in CD4(+) T cells.
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Ahlers JD, Belyakov IM. Lessons learned from natural infection: focusing on the design of protective T cell vaccines for HIV/AIDS. Trends Immunol 2010; 31:120-30. [PMID: 20089450 DOI: 10.1016/j.it.2009.12.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 12/08/2009] [Accepted: 12/11/2009] [Indexed: 01/26/2023]
Abstract
CD8(+) cytotoxic T lymphocyte (CTL) responses are crucial in establishing the control of persistent virus infections. Population studies of HIV-1-infected individuals suggest that CD8(+) CTL responses targeting epitopes that take the greatest toll on virus replication are instrumental in immune control. A major question for vaccine design is whether incorporating epitopes responsible for controlling a persistent virus will translate into protection from natural infection or serve solely as a fail-safe mechanism to prevent overt disease in infected individuals. Here, we discuss qualitative parameters of the CD8(+) CTL response and mechanisms operative in the control of persistent virus infections and suggest new strategies for design and delivery of HIV vaccines.
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Multi-low-dose mucosal simian immunodeficiency virus SIVmac239 challenge of cynomolgus macaques immunized with "hyperattenuated" SIV constructs. J Virol 2009; 84:2304-17. [PMID: 20032177 DOI: 10.1128/jvi.01995-09] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hyperattenuated simian immunodeficiency virus SIVmac239-derived constructs Delta5-CMV and Delta6-CCI are an effort to render SIV incapable of, in practical terms, both reversion and recombination while maintaining the immune features of SIV as a retrovirus. Primary inoculation of cynomolgus macaques with 10(8) 50% tissue culture infective doses (TCID(50)) of Delta5-CMV or Delta6-CCI induced low-level humoral and cellular responses detectable in the absence of measureable in vivo replication. The first of three DNA boosts resulted in elevated gamma interferon (IFN-gamma) enzyme-linked immunospot (ELISPOT) responses to Gag, Pol, and Env in the Delta5-CMV vaccine group compared to the Delta6-CCI vaccine group (P = 0.001). Weekly intrarectal challenge with a low dose of SIVmac239 followed by a dose escalation was conducted until all animals became infected. The mean peak viral load of the Delta5-CMV-vaccinated animals (3.7 x 10(5) copies/ml) was approximately 1 log unit lower than that of the control animals. More dramatically, the viral load set point of these animals was decreased by 3 log units compared to that of the controls (<50 versus 1.64 x 10(4) copies/ml; P < 0.0001). Seventy-five percent (6/8) of vaccine recipients controlled virus below 1,000 copies/ml for at least 6 months, with a subset controlling virus and maintaining substantial CD4 T-cell counts for close to 2 years of follow-up. The correlates of protection from SIV disease progression may lie in the rapidity and protective value of immune responses that occur early in primary SIV infection. Prior immunization with hyperattenuated SIVmac239, even if sterilizing immunity is not achieved, may allow a more advantageous host response.
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