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Johnson AO, Fowler SB, Webster CI, Brown AJ, James DC. Bioinformatic Design of Dendritic Cell-Specific Synthetic Promoters. ACS Synth Biol 2022; 11:1613-1626. [PMID: 35389220 PMCID: PMC9016764 DOI: 10.1021/acssynbio.2c00027] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
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Next-generation DNA vectors for cancer
immunotherapies and vaccine
development require promoters eliciting predefined transcriptional
activities specific to target cell types, such as dendritic cells
(DCs), which underpin immune response. In this study, we describe
the de novo design of DC-specific synthetic promoters via in silico assembly of cis-transcription
factor response elements (TFREs) that harness the DC transcriptional
landscape. Using computational genome mining approaches, candidate
TFREs were identified within promoter sequences of highly expressed
DC-specific genes or those exhibiting an upregulated expression during
DC maturation. Individual TFREs were then screened in vitro in a target DC line and off-target cell lines derived from skeletal
muscle, fibroblast, epithelial, and endothelial cells using homotypic
(TFRE repeats in series) reporter constructs. Based on these data,
a library of heterotypic promoter assemblies varying in the TFRE composition,
copy number, and sequential arrangement was constructed and tested in vitro to identify DC-specific promoters. Analysis of
the transcriptional activity and specificity of these promoters unraveled
underlying design rules, primarily TFRE composition, which govern
the DC-specific synthetic promoter activity. Using these design rules,
a second library of exclusively DC-specific promoters exhibiting varied
transcriptional activities was generated. All DC-specific synthetic
promoter assemblies exhibited >5-fold activity in the target DC
line
relative to off-target cell lines, with transcriptional activities
ranging from 8 to 67% of the nonspecific human cytomegalovirus (hCMV-IE1)
promoter. We show that bioinformatic analysis of a mammalian cell
transcriptional landscape is an effective strategy for de
novo design of cell-type-specific synthetic promoters with
precisely controllable transcriptional activities.
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Affiliation(s)
- Abayomi O. Johnson
- Department of Chemical and Biological Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, U.K
- SynGenSys Limited, Freeths LLP, Norfolk Street, Sheffield S1 2JE, U.K
| | - Susan B. Fowler
- Antibody Discovery and Protein Engineering, R&D, AstraZeneca, Cambridge CB21 6GH, U.K
| | - Carl I. Webster
- Discovery Sciences, R&D, AstraZeneca, Cambridge CB21 6GH, U.K
| | - Adam J. Brown
- Department of Chemical and Biological Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, U.K
- SynGenSys Limited, Freeths LLP, Norfolk Street, Sheffield S1 2JE, U.K
| | - David C. James
- Department of Chemical and Biological Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, U.K
- SynGenSys Limited, Freeths LLP, Norfolk Street, Sheffield S1 2JE, U.K
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Saylor K, Gillam F, Lohneis T, Zhang C. Designs of Antigen Structure and Composition for Improved Protein-Based Vaccine Efficacy. Front Immunol 2020; 11:283. [PMID: 32153587 PMCID: PMC7050619 DOI: 10.3389/fimmu.2020.00283] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 02/04/2020] [Indexed: 12/19/2022] Open
Abstract
Today, vaccinologists have come to understand that the hallmark of any protective immune response is the antigen. However, it is not the whole antigen that dictates the immune response, but rather the various parts comprising the whole that are capable of influencing immunogenicity. Protein-based antigens hold particular importance within this structural approach to understanding immunity because, though different molecules can serve as antigens, only proteins are capable of inducing both cellular and humoral immunity. This fact, coupled with the versatility and customizability of proteins when considering vaccine design applications, makes protein-based vaccines (PBVs) one of today's most promising technologies for artificially inducing immunity. In this review, we follow the development of PBV technologies through time and discuss the antigen-specific receptors that are most critical to any immune response: pattern recognition receptors, B cell receptors, and T cell receptors. Knowledge of these receptors and their ligands has become exceptionally valuable in the field of vaccinology, where today it is possible to make drastic modifications to PBV structure, from primary to quaternary, in order to promote recognition of target epitopes, potentiate vaccine immunogenicity, and prevent antigen-associated complications. Additionally, these modifications have made it possible to control immune responses by modulating stability and targeting PBV to key immune cells. Consequently, careful consideration should be given to protein structure when designing PBVs in the future in order to potentiate PBV efficacy.
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Affiliation(s)
- Kyle Saylor
- Department of Biological Systems Engineering, Virginia Tech, Blacksburg, VA, United States
| | - Frank Gillam
- Department of Biological Systems Engineering, Virginia Tech, Blacksburg, VA, United States
- Locus Biosciences, Morrisville, NC, United States
| | - Taylor Lohneis
- Department of Biological Systems Engineering, Virginia Tech, Blacksburg, VA, United States
- BioPharmaceutical Technology Department, GlaxoSmithKline, Rockville, MD, United States
| | - Chenming Zhang
- Department of Biological Systems Engineering, Virginia Tech, Blacksburg, VA, United States
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3
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The antibiotic resistance-free mammalian expression plasmid vector pPAL for development of third generation vaccines. Plasmid 2018; 101:35-42. [PMID: 30529129 DOI: 10.1016/j.plasmid.2018.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 11/22/2022]
Abstract
DNA vaccines require a vector to replicate genes and express encoding antigens. Antibiotic resistance genes are often used as selection markers, which must not be released to the environment upon final product commercialization. For this reason, generation of antibiotic resistance-free vectors is imperative. The pPAL vector contains the cytomegalovirus enhancer and promoter for expression in mammalian cells and the E. coli fabI chromosomal gene as a selectable marker. The fabI gene encodes the enoyl-ACP reductase (FabI). The bacteriostatic compound triclosan is an inhibitor of this enzyme. Therefore, the selection of positive clones depends on the enzyme:inhibitor molar ratio. According to western blot analysis, the pPAL vector is functional for expression of the Leishmania infantum (Kinetoplastid: Trypanosomatidae) gene encoding for the protein kinase C receptor analog (LACK/p36) in the HEK293T human cell line transfected with pPAL-LACK. The fabI gene sequence contains a 210 bp CpG island, suggesting a potential role as an adjuvant of the antibiotic resistance-free pPAL vector. In fact, Th1 response induction levels against canine leishmaniasis only using pPAL-LACK was shown to be as strong as in previous strategies using a recombinant vaccinia virus in combination with standard mammalian expression plasmid vectors. In summary, the pPAL plasmid contains the essential elements for manipulation and expression of any cloned DNA sequence in prokaryotic and mammalian cells using an E. coli endogenous gene as a selectable marker, which also provides a long CpG island. This element enhances Th1 immune response against L. infantum infection in dogs using the gene encoding for the LACK antigen. Therefore, this antibiotic resistance-free plasmid is a vaccine vector actively participating in protection against canine leishmaniasis and may be potentially tested as a vaccine vector with other antigens against different pathogens.
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4
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Both Major Histocompatibility Complex Class I (MHC-I) and MHC-II Molecules Are Required, while MHC-I Appears To Play a Critical Role in Host Defense against Primary Coxiella burnetii Infection. Infect Immun 2018; 86:IAI.00602-17. [PMID: 29311245 DOI: 10.1128/iai.00602-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 12/19/2017] [Indexed: 01/02/2023] Open
Abstract
To understand the role of class I major histocompatibility complex (MHC-I) and class II MHC (MHC-II) antigen presentation pathways in host defense against Coxiella burnetii infection, we examined whether MHC-I or MHC-II deficiency in mice would significantly influence their susceptibility to virulent C. burnetii Nine Mile phase I (NMI) infection. The results indicate that NMI infection induced more severe disease in both MHC-I-deficient and MHC-II-deficient mice than in wild-type (WT) mice, while only MHC-I-deficient mice developed a severe persistent infection and were unable to control bacterial replication. These results suggest that both MHC-I-restricted CD8+ T cells and MHC-II-restricted CD4+ T cells contribute to host defense against primary C. burnetii infection, while MHC-I-restricted CD8+ T cells appear to play a more critical role in controlling bacterial replication. Additionally, although NMI infection induced more severe disease in TAP1-deficient mice than in their WT counterparts, TAP1 deficiency in mice did not significantly influence their ability to eliminate C. burnetii This suggests that C. burnetii antigen presentation to CD8+ T cells by the MHC-I classical pathway may depend only partially on TAP1. Furthermore, granzyme B deficiency in mice did not significantly alter their susceptibility to C. burnetii infection, but perforin-deficient mice were unable to control host inflammatory responses during primary C. burnetii infection. These results suggest that perforin, but not granzyme B, is required for C. burnetii antigen-specific cytotoxic CD8+ T cells to control primary C. burnetii infection.
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Stone BC, Kas A, Billman ZP, Fuller DH, Fuller JT, Shendure J, Murphy SC. Complex Minigene Library Vaccination for Discovery of Pre-Erythrocytic Plasmodium T Cell Antigens. PLoS One 2016; 11:e0153449. [PMID: 27070430 PMCID: PMC4829254 DOI: 10.1371/journal.pone.0153449] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 03/30/2016] [Indexed: 01/15/2023] Open
Abstract
Development of a subunit vaccine targeting liver-stage Plasmodium parasites requires the identification of antigens capable of inducing protective T cell responses. However, traditional methods of antigen identification are incapable of evaluating T cell responses against large numbers of proteins expressed by these parasites. This bottleneck has limited development of subunit vaccines against Plasmodium and other complex intracellular pathogens. To address this bottleneck, we are developing a synthetic minigene technology for multi-antigen DNA vaccines. In an initial test of this approach, pools of long (150 bp) antigen-encoding oligonucleotides were synthesized and recombined into vectors by ligation-independent cloning to produce two DNA minigene library vaccines. Each vaccine encoded peptides derived from 36 (vaccine 1) and 53 (vaccine 2) secreted or transmembrane pre-erythrocytic P. yoelii proteins. BALB/cj mice were vaccinated three times with a single vaccine by biolistic particle delivery (gene gun) and screened for interferon-γ-producing T cell responses by ELISPOT. Library vaccination induced responses against four novel antigens. Naïve mice exposed to radiation-attenuated sporozoites mounted a response against only one of the four novel targets (PyMDH, malate dehydrogenase). The response to PyMDH could not be recalled by additional homologous sporozoite immunizations but could be partially recalled by heterologous cross-species sporozoite exposure. Vaccination against the dominant PyMDH epitope by DNA priming and recombinant Listeria boosting did not protect against sporozoite challenge. Improvements in library design and delivery, combined with methods promoting an increase in screening sensitivity, may enable complex minigene screening to serve as a high-throughput system for discovery of novel T cell antigens.
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Affiliation(s)
- Brad C. Stone
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, United States of America
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- * E-mail: (BCS); (SCM)
| | - Arnold Kas
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, United States of America
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Zachary P. Billman
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, United States of America
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Deborah H. Fuller
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - James T. Fuller
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Sean C. Murphy
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, United States of America
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
- Seattle Malaria Clinical Trials Center, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Human Challenge Center, Center for Infectious Disease Research, Seattle, Washington, United States of America
- * E-mail: (BCS); (SCM)
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6
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Wedrychowicz H. Antiparasitic DNA vaccines in 21st century. Acta Parasitol 2015; 60:179-89. [PMID: 26203983 PMCID: PMC7088677 DOI: 10.1515/ap-2015-0026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 12/15/2014] [Accepted: 12/17/2014] [Indexed: 11/25/2022]
Abstract
Demands for effective vaccines to control parasitic diseases of humans and livestock have been recently exacerbated by the development of resistance of most pathogenic parasites to anti-parasitic drugs. Novel genomic and proteomic technologies have provided opportunities for the discovery and improvement of DNA vaccines which are relatively easy as well as cheap to fabricate and stable at room temperatures. However, their main limitation is rather poor immunogenicity, which makes it necessary to couple the antigens with adjuvant molecules. This paper review recent advances in the development of DNA vaccines to some pathogenic protozoa and helminths. Numerous studies were conducted over the past 14 years of 21st century, employing various administration techniques, adjuvants and new immunogenic antigens to increase efficacy of DNA vaccines. Unfortunately, the results have not been rewarding. Further research is necessary using more extensive combinations of antigens; alternate delivery systems and more efficient adjuvants based on knowledge of the immunomodulatory capacities of parasitic protozoa and helminths.
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MESH Headings
- Animals
- Disease Transmission, Infectious/prevention & control
- Drug Discovery/trends
- Helminthiasis/immunology
- Helminthiasis/prevention & control
- Helminthiasis/transmission
- Helminthiasis, Animal/immunology
- Helminthiasis, Animal/prevention & control
- Helminthiasis, Animal/transmission
- Humans
- Protozoan Infections/immunology
- Protozoan Infections/prevention & control
- Protozoan Infections/transmission
- Protozoan Infections, Animal/immunology
- Protozoan Infections, Animal/prevention & control
- Protozoan Infections, Animal/transmission
- Vaccines, DNA/administration & dosage
- Vaccines, DNA/immunology
- Vaccines, DNA/isolation & purification
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Affiliation(s)
- Halina Wedrychowicz
- Department of Molecular Biology, Laboratory of Molecular Parasitology, W. Stefański Institute Parasitology, Polish Academy of Sciences, 51/55 Twarda St., 00-818 Warsaw, Poland
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Calvet CY, André FM, Mir LM. Dual therapeutic benefit of electroporation-mediated DNA vaccination in vivo: Enhanced gene transfer and adjuvant activity. Oncoimmunology 2014; 3:e28540. [PMID: 25050220 PMCID: PMC4077865 DOI: 10.4161/onci.28540] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 03/14/2014] [Indexed: 01/08/2023] Open
Abstract
DNA vaccination consists of administering an antigen-coding nucleotide sequence. In order to improve the efficacy of DNA vaccines, electroporation is one of the most commonly used methods to enhance DNA uptake. Here, we discuss additional immunological effects of electroporation that are key aspects for inducing immunity in response to DNA vaccines.
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Affiliation(s)
- Christophe Y Calvet
- Univ Paris-Sud; Laboratoire de Vectorologie et Thérapeutiques Anticancéreuses; UMR 8203; Villejuif, France ; CNRS; Laboratoire de Vectorologie et Thérapeutiques Anticancéreuses; UMR 8203; Villejuif, France ; Gustave Roussy; Laboratoire de Vectorologie et Thérapeutiques Anticancéreuses; UMR 8203; Villejuif, France
| | - Franck M André
- Univ Paris-Sud; Laboratoire de Vectorologie et Thérapeutiques Anticancéreuses; UMR 8203; Villejuif, France ; CNRS; Laboratoire de Vectorologie et Thérapeutiques Anticancéreuses; UMR 8203; Villejuif, France ; Gustave Roussy; Laboratoire de Vectorologie et Thérapeutiques Anticancéreuses; UMR 8203; Villejuif, France
| | - Lluis M Mir
- Univ Paris-Sud; Laboratoire de Vectorologie et Thérapeutiques Anticancéreuses; UMR 8203; Villejuif, France ; CNRS; Laboratoire de Vectorologie et Thérapeutiques Anticancéreuses; UMR 8203; Villejuif, France ; Gustave Roussy; Laboratoire de Vectorologie et Thérapeutiques Anticancéreuses; UMR 8203; Villejuif, France
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8
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Fusion of ubiquitin to HIV gag impairs human monocyte-derived dendritic cell maturation and reduces ability to induce gag T cell responses. PLoS One 2014; 9:e88327. [PMID: 24505475 PMCID: PMC3914991 DOI: 10.1371/journal.pone.0088327] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 01/12/2014] [Indexed: 12/25/2022] Open
Abstract
The efficient induction of CD8 T cell immunity is dependent on the processing and presentation of antigen on MHC class I molecules by professional antigen presenting cells (APC). To develop an improved T cell vaccine for HIV we investigated whether fusing the ubiquitin gene to the N terminus of the HIV gag gene enhanced targeting to the proteasome resulting in better CD8 T cell responses. Human monocyte derived dendritic cells (moDC), transduced with adenovirus vectors carrying either ubiquitinated or non-ubiquitinated gag transgene constructs, were co-cultured with autologous naïve T cells and T cell responses were measured after several weekly cycles of stimulation. Despite targeting of the ubiquitin gag transgene protein to the proteasome, ubiquitination did not increase CD8 T cell immune responses and in some cases diminished responses to gag peptides. There were no marked differences in cytokines produced from ubiquitinated and non-ubiquitinated gag stimulated cultures or in the expression of inhibitory molecules on expanded T cells. However, the ability of moDC transduced with ubiquitinated gag gene to upregulate co-stimulatory molecules was reduced, whilst no difference in moDC maturation was observed with a control ubiquitinated and non-ubiquitinated MART gene. Furthermore moDC transduced with ubiquitinated gag produced more IL-10 than transduction with unmodified gag. Thus failure of gag ubiquitination to enhance CD8 responses may be caused by suppression of moDC maturation. These results indicate that when designing a successful vaccine strategy to target a particular cell population, attention must also be given to the effect of the vaccine on APCs.
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9
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Benlahrech A, Meiser A, Herath S, Papagatsias T, Athanasopoulos T, Li F, Self S, Bachy V, Hervouet C, Logan K, Klavinskis L, Dickson G, Patterson S. Fragmentation of SIV-gag vaccine induces broader T cell responses. PLoS One 2012; 7:e48038. [PMID: 23118924 PMCID: PMC3485275 DOI: 10.1371/journal.pone.0048038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 09/20/2012] [Indexed: 12/28/2022] Open
Abstract
Background High mutation rates of human immunodeficiency virus (HIV) allows escape from T cell recognition preventing development of effective T cell vaccines. Vaccines that induce diverse T cell immune responses would help overcome this problem. Using SIV gag as a model vaccine, we investigated two approaches to increase the breadth of the CD8 T cell response. Namely, fusion of vaccine genes to ubiquitin to target the proteasome and increase levels of MHC class I peptide complexes and gene fragmentation to overcome competition between epitopes for presentation and recognition. Methodology/Principal Findings Three vaccines were compared: full-length unmodified SIV-mac239 gag, full-length gag fused at the N-terminus to ubiquitin and 7 gag fragments of equal size spanning the whole of gag with ubiquitin-fused to the N-terminus of each fragment. Genes were cloned into a replication defective adenovirus vector and immunogenicity assessed in an in vitro human priming system. The breadth of the CD8 T cell response, defined by the number of distinct epitopes, was assessed by IFN-γ-ELISPOT and memory phenotype and cytokine production evaluated by flow cytometry. We observed an increase of two- to six-fold in the number of epitopes recognised in the ubiquitin-fused fragments compared to the ubiquitin-fused full-length gag. In contrast, although proteasomal targeting was achieved, there was a marked reduction in the number of epitopes recognised in the ubiquitin-fused full-length gag compared to the full-length unmodified gene, but there were no differences in the number of epitope responses induced by non-ubiquitinated full-length gag and the ubiquitin-fused mini genes. Fragmentation and ubiquitination did not affect T cell memory differentiation and polyfunctionality, though most responses were directed against the Ad5 vector. Conclusion/Significance Fragmentation but not fusion with ubiquitin increases the breadth of the CD8 T vaccine response against SIV-mac239 gag. Thus gene fragmentation of HIV vaccines may maximise responses.
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Affiliation(s)
- Adel Benlahrech
- Department of Medicine, Imperial College London, Chelsea and Westminster Hospital, London, United Kingdom
| | - Andrea Meiser
- Department of Medicine, Imperial College London, Chelsea and Westminster Hospital, London, United Kingdom
| | - Shanthi Herath
- Department of Medicine, Imperial College London, Chelsea and Westminster Hospital, London, United Kingdom
| | - Timos Papagatsias
- Department of Medicine, Imperial College London, Chelsea and Westminster Hospital, London, United Kingdom
| | - Takis Athanasopoulos
- School of Biological Science, Royal Holloway University of London, Egham, United Kingdom
| | - Fucheng Li
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Steve Self
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Veronique Bachy
- Peter Gorer Department of Immunobiology, Guys Hospital, Kings College London, London, United Kingdom
| | - Catherine Hervouet
- Peter Gorer Department of Immunobiology, Guys Hospital, Kings College London, London, United Kingdom
| | - Karen Logan
- Department of Immunology, Imperial College London, London, United Kingdom
| | - Linda Klavinskis
- Peter Gorer Department of Immunobiology, Guys Hospital, Kings College London, London, United Kingdom
| | - George Dickson
- School of Biological Science, Royal Holloway University of London, Egham, United Kingdom
| | - Steven Patterson
- Department of Medicine, Imperial College London, Chelsea and Westminster Hospital, London, United Kingdom
- * E-mail:
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10
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Wang QM, Tang Y, Lei CX, Shi FZ, Liu QH. Enhanced cellular immune response elicited by a DNA vaccine fused with Ub against Mycobacterium tuberculosis. Scand J Immunol 2012; 76:123-30. [PMID: 22540309 DOI: 10.1111/j.1365-3083.2012.02719.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study evaluated the immune response elicited by a Ub-fused Ag85A DNA vaccine against Mycobacterium tuberculosis. BALB/c mice were vaccinated with plasmid DNA encoding Ag85A protein, Ub-fused Ag85A DNA vaccine (UbGR-Ag85A) and negative DNA vaccines, respectively. Ag85A DNA vaccine immunization induced a Th(l)-polarized immune response. The production of Th(l)-type cytokine (IFN-γ) and proliferative T cell responses was enhanced significantly in mice immunized with UbGR-Ag85A fusion DNA vaccine, compared with non-fusion DNA vaccine. Moreover, this fusion DNA vaccine also resulted in an increased relative ratio of IgG(2a) to IgG(l) and the cytotoxicity of T cells. IFN-γ intracellular staining of splenocytes indicated that UbGR-Ag85A fusion DNA vaccine activated CD4(+) and CD8(+) T cells, particularly CD8(+) T cells. Thus, this study demonstrated that the UbGR-Ag85A fusion DNA vaccine inoculation could improve antigen-specific cellular immune responses, which is helpful for protection against TB infection.
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Affiliation(s)
- Q-M Wang
- The Division of aviation medicine, Institute of Naval Medical Research, Shanghai, China. wqqmm_888@ yahoo.com
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11
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Wang Q, Lei C, Wan H, Liu Q. Improved cellular immune response elicited by a ubiquitin-fused DNA vaccine against Mycobacterium tuberculosis. DNA Cell Biol 2011; 31:489-95. [PMID: 21905875 DOI: 10.1089/dna.2011.1309] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study evaluated the immune response elicited by a ubiquitin (Ub)-fused MPT64 DNA vaccine against Mycobacterium tuberculosis. BALB/c mice were vaccinated with plasmid DNA encoding MPT64 protein, Ub-fused MPT64 DNA vaccine (UbGR-MPT64), and negative DNA vaccines, respectively. MPT64 DNA vaccine immunization induced a Thl-polarized immune response. The production of Thl-type cytokine (interferon-gamma [IFN-γ]) and proliferative T cell responses were enhanced significantly in mice immunized with UbGR-MPT64 fusion DNA vaccine, compared with nonfusion DNA vaccine. Moreover, this fusion DNA vaccine also resulted in an increased relative ratio of IgG2a to IgGl and the cytotoxicity of T cells. IFN-γ intracellular staining of splenocytes indicated that UbGR-mpt64 fusion DNA vaccine activated CD4+ and CD8+ T cells, particularly CD8+ T cells. Thus, this study demonstrated that the UbGR-MPT64 fusion DNA vaccine inoculation could improve antigen-specific cellular immune responses, which is helpful for protection against TB.
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Affiliation(s)
- Qingmin Wang
- The Division of Aviation Medicine, Institute of Naval Medical Research, Shanghai, China. wqqmm_888@ yahoo.com
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12
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Ingolotti M, Kawalekar O, Shedlock DJ, Muthumani K, Weiner DB. DNA vaccines for targeting bacterial infections. Expert Rev Vaccines 2010; 9:747-63. [PMID: 20624048 DOI: 10.1586/erv.10.57] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
DNA vaccination has been of great interest since its discovery in the 1990s due to its ability to elicit both humoral and cellular immune responses. DNA vaccines consist of a DNA plasmid containing a transgene that encodes the sequence of a target protein from a pathogen under the control of a eukaryotic promoter. This revolutionary technology has proven to be effective in animal models and four DNA vaccine products have recently been approved for veterinary use. Although few DNA vaccines against bacterial infections have been tested, the results are encouraging. Because of their versatility, safety and simplicity a wider range of organisms can be targeted by these vaccines, which shows their potential advantages to public health. This article describes the mechanism of action of DNA vaccines and their potential use for targeting bacterial infections. In addition, it provides an updated summary of the methods used to enhance immunogenicity from codon optimization and adjuvants to delivery techniques including electroporation and use of nanoparticles.
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Affiliation(s)
- Mariana Ingolotti
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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13
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Bernard D, Ventresca MS, Marshall LA, Evelegh C, Wan Y, Bramson JL. Processing of tumor antigen differentially impacts the development of helper and effector CD4+ T-cell responses. Mol Ther 2010; 18:1224-32. [PMID: 20179673 DOI: 10.1038/mt.2010.30] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
CD4(+) T cells contribute to the antitumor T-cell response as both effectors that promote tumor rejection and helpers that facilitate the activation of other antitumor effector cells, such as CD8(+) T cells. Maximal engagement of both effector and helper CD4(+) T-cell responses is a desirable attribute of cancer vaccines. We have employed the B16F10 murine melanoma model and a series of recombinant adenovirus (Ad) vaccines expressing mutant forms of the tumor antigen, dopachrome tautomerase, to investigate the relationship between antigen processing and the antitumor CD4(+) T-cell response. Our results have revealed an unexpected dichotomy in the generation of helper and effector CD4(+) T-cell responses where CD4(+) T effector responses are dependent upon protein processing and trafficking, whereas CD4(+) T helper responses are not. The results have important implications for strategies aimed at augmenting antigen immunogenicity by altering intracellular processing and localization.
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Affiliation(s)
- Dannie Bernard
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
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Abstract
There is currently no licensed vaccine for brucellosis in humans. Available animal vaccines may cause disease and are considered unsuitable for use in humans. However, the causative pathogen, Brucella, is among the most common causes of laboratory-acquired infections and is a Center for Disease Control category B select agent. Thus, human vaccines for brucellosis are required. This review highlights the considerations that are needed in the journey to develop a human vaccine, including animal models, and includes an assessment of the current status of novel vaccine candidates.
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Affiliation(s)
- Stuart D Perkins
- Department of Biomedical Sciences, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire, UK
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15
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Yang K, Sun K, Srinivasan KN, Salmon J, Marques ET, Xu J, August JT. Immune responses to T-cell epitopes of SARS CoV-N protein are enhanced by N immunization with a chimera of lysosome-associated membrane protein. Gene Ther 2009; 16:1353-62. [PMID: 19727132 PMCID: PMC7091638 DOI: 10.1038/gt.2009.92] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2008] [Revised: 05/11/2009] [Accepted: 06/05/2009] [Indexed: 12/30/2022]
Abstract
In our previous study by Gupta et al, dominant T-cell epitopes of SARS CoV-N(N) protein were predicted by software. The spectrum of interferon (IFN)-gamma responses of Balb/c mice immunized against two different forms of SARS CoV-N plasmid was then analyzed. A cluster of dominant T-cell epitopes of SARS CoV-N protein was found in the N-terminus (amino acids 76-114). On the basis of this study, four different plasmids were constructed: (i) DNA encoding the unmodified N (p-N) or N(70-122) (p-N(70-122)) as an endogenous cytoplasmic protein or (ii) DNA encoding a lysosome-associated membrane protein (LAMP) chimera with N (p-LAMP/N) or N(70-122) (p-LAMP/N(70-122)). The immune responses of mice to these four constructs were evaluated. The results showed marked differences in the responses of the immunized mice. A single priming immunization with the p-LAMP/N construct was sufficient to elicit an antibody response. Enzyme-linked immunospot (ELISpot) assay indicated that p-LAMP/N(70-122) and p-LAMP/N plasmids both elicited a greater IFN-gamma response than p-N. p-N and p-N(70-122) constructs induced low or undetectable levels of cytokine secretion. We also found that the p-LAMP/N(70-122) construct promoted a long-lasting T-cell memory response without an additional boost 6 months after three immunizations. These findings show that DNA vaccines, even epitope-based DNA vaccines using LAMP as chimera, can elicit both humoral and cellular immune responses.
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Affiliation(s)
- K Yang
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD USA
- Department of Immunology, The Fourth Military Medical University, Xi'an, Shaanxi Province, PR China,
| | - K Sun
- Division of Biomedical Sciences, Johns Hopkins in Singapore, Singapore
| | - K N Srinivasan
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD USA
- Product Evaluation and Registration Division, Centre for Drug Administration, Health Sciences Authority, Singapore
| | - J Salmon
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - E T Marques
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD USA
- Division of Infectious Diseases, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - J Xu
- Department of Neurology, Tangdu Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, PR China,
| | - J T August
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD USA
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16
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Wang QM, Kang L, Wang XH. Improved cellular immune response elicited by a ubiquitin-fused ESAT-6 DNA vaccine against Mycobacterium tuberculosis. Microbiol Immunol 2009; 53:384-90. [PMID: 19563397 DOI: 10.1111/j.1348-0421.2009.00138.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The present study evaluated the immune response elicited by a ubiquitin-fused ESAT-6 DNA vaccine against Mycobacterium tuberculosis. BALB/c mice were vaccinated with plasmid DNA encoding ESAT-6 protein, ubiquitin-fused ESAT-6 DNA vaccine (UbGR-ESAT-6), pcDNA3-ubiquitin and blank vector, respectively. ESAT-6 DNA vaccine immunization induced a Thl-polarized immune response. The production of Thl-type cytokine (IFN-gamma) and proliferative T-cell responses was enhanced significantly in mice immunized with UbGR-ESAT-6 fusion DNA vaccine, compared to non-fusion DNA vaccine. This fusion DNA vaccine also resulted in an increased relative ratio of IgG(2a) to IgG(l) and the cytotoxicity of T cells. Thus, the present study demonstrated that the UbGR-ESAT-6 fusion DNA vaccine inoculation improved antigen-specific cellular immune responses, which is helpful for protection against tuberculosis infection.
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Affiliation(s)
- Qing-min Wang
- The Ship Environmental Health Division, Institute of Navy Medicine Research, Xiangyin Road 880, Shanghai, China.
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17
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Kaur M, Saxena A, Rai A, Bhatnagar R. Rabies DNA vaccine encoding lysosome‐targeted glycoprotein supplemented with Emulsigen‐D confers complete protection in preexposure and postexposure studies in BALB/c mice. FASEB J 2009; 24:173-83. [DOI: 10.1096/fj.09-138644] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Manpreet Kaur
- Laboratory of Molecular Biology and Genetic EngineeringSchool of BiotechnologyJawaharlal Nehru UniversityNew DelhiIndia
| | - Ankur Saxena
- National Biotechnology CenterIndian Veterinary Research InstituteIzatnagarIndia
| | - Anant Rai
- National Biotechnology CenterIndian Veterinary Research InstituteIzatnagarIndia
| | - Rakesh Bhatnagar
- Laboratory of Molecular Biology and Genetic EngineeringSchool of BiotechnologyJawaharlal Nehru UniversityNew DelhiIndia
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18
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Honda M, Wang R, Kong WP, Kanekiyo M, Akahata W, Xu L, Matsuo K, Natarajan K, Robinson H, Asher TE, Price DA, Douek DC, Margulies DH, Nabel GJ. Different vaccine vectors delivering the same antigen elicit CD8+ T cell responses with distinct clonotype and epitope specificity. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2009; 183:2425-34. [PMID: 19620307 PMCID: PMC2858449 DOI: 10.4049/jimmunol.0900581] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Prime-boost immunization with gene-based vectors has been developed to generate more effective vaccines for AIDS, malaria, and tuberculosis. Although these vectors elicit potent T cell responses, the mechanisms by which they stimulate immunity are not well understood. In this study, we show that immunization by a single gene product, HIV-1 envelope, with alternative vector combinations elicits CD8(+) cells with different fine specificities and kinetics of mobilization. Vaccine-induced CD8(+) T cells recognized overlapping third V region loop peptides. Unexpectedly, two anchor variants bound H-2D(d) better than the native sequences, and clones with distinct specificities were elicited by alternative vectors. X-ray crystallography revealed major differences in solvent exposure of MHC-bound peptide epitopes, suggesting that processed HIV-1 envelope gave rise to MHC-I/peptide conformations recognized by distinct CD8(+) T cell populations. These findings suggest that different gene-based vectors generate peptides with alternative conformations within MHC-I that elicit distinct T cell responses after vaccination.
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Affiliation(s)
- Mitsuo Honda
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Rui Wang
- Molecular Biology Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Wing-Pui Kong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Masaru Kanekiyo
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Wataru Akahata
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Ling Xu
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Kazuhiro Matsuo
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kannan Natarajan
- Molecular Biology Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | | | - Tedi E. Asher
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - David A. Price
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
- Department of Medical Biochemistry and Immunology, Cardiff University Medical School, Cardiff, United Kingdom
| | - Daniel C. Douek
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - David H. Margulies
- Molecular Biology Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Gary J. Nabel
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
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19
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The protective immune response against infectious bronchitis virus induced by multi-epitope based peptide vaccines. Biosci Biotechnol Biochem 2009; 73:1500-4. [PMID: 19584555 DOI: 10.1271/bbb.80864] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Peptide vaccine was found to be an effective and powerful approach to a variety of pathogens. To explore multi-epitope based peptide vaccines against infectious bronchitis virus (IBV), the immunogenic peptides were fused to the 3' terminal of glutathione S transferase gene (GST) and expressed in Escherichia coli. ELISA and Western blot analysis showed that the purified fusion proteins had excellent immune activity with chicken anti-IBV serum. During the vaccination course, the candidate peptide vaccines induced strong humoral and cellular response, and provided up to 80.0% immune protection, while all non-immunized chickens in the negative control group manifested obvious typical symptoms and died after virus challenge. Our finding provides a new way to develop multi-epitope based peptide vaccine against IBV.
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20
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Kaur M, Rai A, Bhatnagar R. Rabies DNA vaccine: no impact of MHC class I and class II targeting sequences on immune response and protection against lethal challenge. Vaccine 2009; 27:2128-37. [PMID: 19356616 PMCID: PMC7115670 DOI: 10.1016/j.vaccine.2009.01.128] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 01/24/2009] [Accepted: 01/29/2009] [Indexed: 11/23/2022]
Abstract
Rabies is progressive fatal encephalitis. WHO estimates 55,000 rabies deaths and more than 10 million PEP every year world-wide. A variety of cell-culture derived vaccines are available for prophylaxis against rabies. However, their high cost restricts their usage in developing countries, where such cases are most often encountered. This is driving the quest for newer vaccine formulations; DNA vaccines being most promising amongst them. Here, we explored strategies of antigen trafficking to various cellular compartments aiming at improving both humoral and cellular immunity. These strategies include use of signal sequences namely Tissue Plasminogen Activator (TPA), Ubiquitin (UQ) and Lysosomal-Associated Membrane Protein-1 (LAMP-1). TPA, LAMP-1 and their combination were aimed at enhancing the CD4(+) T cell and antibody response. In contrast, the UQ tag was utilized for enhancing CD8(+) response. The potency of modified DNA vaccines assessed by total antibody response, antibody isotypes, cytokine profile, neutralizing antibody titer and protection conferred against in vivo challenge; was enhanced in comparison to native unmodified vaccine, but the response elicited did not pertain to the type of target sequence and the directed arm of immunity. Interestingly, the DNA vaccines that had been designed to generate different type of immune responses yielded in effect similar response. In conclusion, our data indicate that the directing target sequence is not the exclusive deciding factor for type and extent of immune response elicited and emphasizes on the antigen dependence of immune enhancement strategies.
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Key Words
- ab, antibody
- ig, immunoglobulin
- elisa, enzyme linked immunosorbent assay
- gp, glycoprotein
- lamp-1, lysosomal-associated membrane protein-1
- mhc, major histocompatibility complex
- mq, milli quartz water
- pmsf, phenyl methyl sulphonyl fluoride
- ripa, radioimmunoprecipitation assay buffer
- rffit, rapid fluorescence focus inhibition test
- tm, transmembrane
- tpa, tissue plasminogen activator
- tris, tris(hydroxymethyl) aminomethane
- uq, ubiquitin
- targeting sequence
- rabies virus-neutralizing antibody (rvna)
- survival
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Affiliation(s)
- Manpreet Kaur
- Laboratory Of Molecular Biology And Genetic Engineering, School Of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, Delhi, India
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21
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YANG T, WANG HN, WANG X, TANG JN, GAO R, LI J, GUO ZC, LI YL. Multivalent DNA Vaccine Enhanced Protection Efficacy against Infectious Bronchitis Virus in Chickens. J Vet Med Sci 2009; 71:1585-90. [DOI: 10.1292/jvms.001585] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Tai YANG
- Animal Disease Prevention and Food Safety Key Lab of Sichuan Province, School of Life Sciences, Sichuan University
| | - Hong-Ning WANG
- Animal Disease Prevention and Food Safety Key Lab of Sichuan Province, School of Life Sciences, Sichuan University
| | - Xue WANG
- Animal Disease Prevention and Food Safety Key Lab of Sichuan Province, School of Life Sciences, Sichuan University
| | - Jun-Ni TANG
- Animal Disease Prevention and Food Safety Key Lab of Sichuan Province, School of Life Sciences, Sichuan University
| | - Rong GAO
- Animal Disease Prevention and Food Safety Key Lab of Sichuan Province, School of Life Sciences, Sichuan University
| | - Juan LI
- Animal Disease Prevention and Food Safety Key Lab of Sichuan Province, School of Life Sciences, Sichuan University
| | - Zi-Cheng GUO
- Animal Disease Prevention and Food Safety Key Lab of Sichuan Province, School of Life Sciences, Sichuan University
| | - Yu-Ling LI
- Animal Disease Prevention and Food Safety Key Lab of Sichuan Province, School of Life Sciences, Sichuan University
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22
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Sacco RE. DNA vaccines against infectious agents: recent strategies for enhancing immune responses. Expert Opin Ther Pat 2008. [DOI: 10.1517/13543776.18.4.365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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23
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Ilyinskii PO, Meriin AB, Gabai VL, Zhirnov OP, Thoidis G, Shneider AM. Prime-boost vaccination with a combination of proteosome-degradable and wild-type forms of two influenza proteins leads to augmented CTL response. Vaccine 2008; 26:2177-85. [PMID: 18400345 DOI: 10.1016/j.vaccine.2008.02.050] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 02/12/2008] [Accepted: 02/22/2008] [Indexed: 02/04/2023]
Abstract
Targeting viral antigens for proteosomal degradation has previously been proposed as a means for immunogenicity augmentation. However, utilization of modified unstable antigens may be insufficient for potent T-cell cross-presentation by APCs, a mechanism that requires high levels of the antigenic protein. Therefore, we hypothesized that a recombinant vaccine utilizing a combination of proteosome-sensitive and proteosome-resistant versions of an antigen in a prime-boost regimen may provide the most efficient CTL response. To address this hypothesis, we utilized conserved proteosome-resistant influenza A virus proteins M1 and NS1. Unstable versions of these polypeptides were constructed by destroying their 3D structure via truncations or short insertions into predicted alpha-helical structures. These modified polypeptides were stabilized in the presence of the proteosome inhibitor MG132, strongly suggesting that they are degraded via a ubiquitin-proteosome pathway. Importantly, with both M1 and NS1antigens, homologous DNA vaccination with a mixture of unstable and proteosome-resistant wt forms of these proteins resulted in significantly higher CTL activity than vaccination with either wt or degradable forms. The most dramatic effect was seen with NS1, where homologous immunization with a mixture of these two forms was the only regimen that produced a notable elevation of CTL response, compared to vaccination with the wt NS1. Additionally, for M1 protein, heterologous vaccination utilizing the unstable form as prime and wild-type form as boost, demonstrated significant augmentation of the CTL response. These data indicate that combining proteosome-sensitive and proteosome-resistant forms of an antigen during vaccination is advantageous.
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