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Bruder JT, Chen P, Ekberg G, Smith EC, Lazarski CA, Myers BA, Bolton J, Sedegah M, Villasante E, Richie TL, King CR, Aguiar JC, Doolan DL, Brough DE. Profiling the Targets of Protective CD8 + T Cell Responses to Infection. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2017; 7:20-31. [PMID: 28948187 PMCID: PMC5602877 DOI: 10.1016/j.omtm.2017.08.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 08/14/2017] [Indexed: 11/22/2022]
Abstract
T cells are critical effectors of host immunity that target intracellular pathogens, such as the causative agents of HIV, tuberculosis, and malaria. The development of vaccines that induce effective cell-mediated immunity against such pathogens has proved challenging; for tuberculosis and malaria, many of the antigens targeted by protective T cells are not known. Here, we report a novel approach for screening large numbers of antigens as potential targets of T cells. Malaria provides an excellent model to test this antigen discovery platform because T cells are critical mediators of protection following immunization with live sporozoite vaccines and the specific antigen targets are unknown. We generated an adenovirus array by cloning 312 highly expressed pre-erythrocytic Plasmodium yoelii antigens into adenovirus vectors using high-throughput methodologies. The array was screened to identify antigen-specific CD8+ T cells induced by a live sporozoite vaccine regimen known to provide high levels of sterile protection mediated by CD8+ T cells. We identified 69 antigens that were targeted by CD8+ T cells induced by this vaccine regimen. The antigen that recalled the highest frequency of CD8+ T cells, PY02605, induced protective responses in mice, demonstrating proof of principle for this approach in identifying antigens for vaccine development.
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Affiliation(s)
- Joseph T. Bruder
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
- Corresponding author: Joseph T. Bruder, Summit Consulting, 567 Chestertown Street, Gaithersburg, MD 20878, USA.
| | - Ping Chen
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
| | - Greg Ekberg
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
| | - Emily C. Smith
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Drive, Suite 100, Bethesda, MD 20817, USA
| | | | - Bennett A. Myers
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
| | - Jessica Bolton
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Drive, Suite 100, Bethesda, MD 20817, USA
| | - Martha Sedegah
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Eileen Villasante
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Thomas L. Richie
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - C. Richter King
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
| | - Joao C. Aguiar
- Malaria Department, Naval Medical Research Center (NMRC), 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
- Camris International, 3 Bethesda Metro Center, 16th Floor, Bethesda, MD 20814, USA
| | - Denise L. Doolan
- Australian Institute of Tropical Health and Medicine, James Cook University, McGregor Road, Cairns, QLD 4870, Australia
| | - Douglas E. Brough
- GenVec, Inc., 910 Clopper Road, Suite 220N, Gaithersburg, MD 20878, USA
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Suschak JJ, Williams JA, Schmaljohn CS. Advancements in DNA vaccine vectors, non-mechanical delivery methods, and molecular adjuvants to increase immunogenicity. Hum Vaccin Immunother 2017; 13:2837-2848. [PMID: 28604157 PMCID: PMC5718814 DOI: 10.1080/21645515.2017.1330236] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
A major advantage of DNA vaccination is the ability to induce both humoral and cellular immune responses. DNA vaccines are currently used in veterinary medicine, but have not achieved widespread acceptance for use in humans due to their low immunogenicity in early clinical studies. However, recent clinical data have re-established the value of DNA vaccines, particularly in priming high-level antigen-specific antibody responses. Several approaches have been investigated for improving DNA vaccine efficacy, including advancements in DNA vaccine vector design, the inclusion of genetically engineered cytokine adjuvants, and novel non-mechanical delivery methods. These strategies have shown promise, resulting in augmented adaptive immune responses in not only mice, but also in large animal models. Here, we review advancements in each of these areas that show promise for increasing the immunogenicity of DNA vaccines.
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Affiliation(s)
- John J Suschak
- a U.S. Army Medical Research Institute of Infectious Diseases , Fort Detrick , MD , USA
| | | | - Connie S Schmaljohn
- a U.S. Army Medical Research Institute of Infectious Diseases , Fort Detrick , MD , USA
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Luo K, Zhang H, Zavala F, Biragyn A, Espinosa DA, Markham RB. Fusion of antigen to a dendritic cell targeting chemokine combined with adjuvant yields a malaria DNA vaccine with enhanced protective capabilities. PLoS One 2014; 9:e90413. [PMID: 24599116 PMCID: PMC3943962 DOI: 10.1371/journal.pone.0090413] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 01/30/2014] [Indexed: 12/31/2022] Open
Abstract
Although sterilizing immunity to malaria can be elicited by irradiated sporozoite vaccination, no clinically practical subunit vaccine has been shown to be capable of preventing the approximately 600,000 annual deaths attributed to this infection. DNA vaccines offer several potential advantages for a disease that primarily affects the developing world, but new approaches are needed to improve the immunogenicity of these vaccines. By using a novel, lipid-based adjuvant, Vaxfectin, to attract immune cells to the immunization site, in combination with an antigen-chemokine DNA construct designed to target antigen to immature dendritic cells, we elicited a humoral immune response that provided sterilizing immunity to malaria challenge in a mouse model system. The chemokine, MIP3αCCL20, did not significantly enhance the cellular infiltrate or levels of cytokine or chemokine expression at the immunization site but acted with Vaxfectin to reduce liver stage malaria infection by orders of magnitude compared to vaccine constructs lacking the chemokine component. The levels of protection achieved were equivalent to those observed with irradiated sporozoites, a candidate vaccine undergoing development for further large scale clinical trial. Only vaccination with the combined regimen of adjuvant and chemokine provided 80–100% protection against the development of bloodstream infection. Treating the immunization process as requiring the independent steps of 1) attracting antigen-presenting cells to the site of immunization and 2) specifically directing vaccine antigen to the immature dendritic cells that initiate the adaptive immune response may provide a rational strategy for the development of a clinically applicable malaria DNA vaccine.
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Affiliation(s)
- Kun Luo
- The Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Hong Zhang
- The Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Fidel Zavala
- The Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Arya Biragyn
- Immunoregulation Section, Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, Maryland, United States of America
| | - Diego A. Espinosa
- The Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Richard B. Markham
- The Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail:
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Vaxfectin adjuvant improves antibody responses of juvenile rhesus macaques to a DNA vaccine encoding the measles virus hemagglutinin and fusion proteins. J Virol 2013; 87:6560-8. [PMID: 23552419 DOI: 10.1128/jvi.00635-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
DNA vaccines formulated with the cationic lipid-based adjuvant Vaxfectin induce protective immunity in macaques after intradermal (i.d.) or intramuscular (i.m.) delivery of 0.5 to 1 mg of codon-optimized DNA encoding the hemagglutinin (H) and fusion (F) proteins of measles virus (MeV). To characterize the effect of Vaxfectin at lower doses of H+F DNA, rhesus macaques were vaccinated twice with 20 μg of DNA plus Vaxfectin i.d., 100 μg of DNA plus Vaxfectin i.d., 100 μg of DNA plus Vaxfectin i.m. or 100 μg of DNA plus phosphate-buffered saline (PBS) i.m. using a needleless Biojector device. The levels of neutralizing (P = 0.036) and binding (P = 0.0001) antibodies were higher after 20 or 100 μg of DNA plus Vaxfectin than after 100 μg of DNA plus PBS. Gamma interferon (IFN-γ)-producing T cells were induced more rapidly than antibody, but were not improved with Vaxfectin. At 18 months after vaccination, monkeys were challenged with wild-type MeV. None developed rash or viremia, but all showed evidence of infection. Antibody levels increased, and IFN-γ- and interleukin-17-producing T cells, including cells specific for the nucleoprotein absent from the vaccine, were induced. At 3 months after challenge, MeV RNA was detected in the leukocytes of two monkeys. The levels of antibody peaked 2 to 4 weeks after challenge and then declined in vaccinated animals reflecting low numbers of bone marrow-resident plasma cells. Therefore, Vaxfectin was dose sparing and substantially improved the antibody response to the H+F DNA vaccine. This immune response led to protection from disease (rash/viremia) but not from infection. Antibody responses after challenge were more transient in vaccinated animals than in an unvaccinated animal.
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Nonclinical biodistribution, integration, and toxicology evaluations of an H5N1 pandemic influenza plasmid DNA vaccine formulated with Vaxfectin®. Vaccine 2011; 29:5443-52. [DOI: 10.1016/j.vaccine.2011.05.060] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 04/20/2011] [Accepted: 05/19/2011] [Indexed: 11/19/2022]
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Sullivan SM, Doukas J, Hartikka J, Smith L, Rolland A. Vaxfectin: a versatile adjuvant for plasmid DNA- and protein-based vaccines. Expert Opin Drug Deliv 2011; 7:1433-46. [PMID: 21118032 DOI: 10.1517/17425247.2010.538047] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
IMPORTANCE OF THE FIELD Many vaccines require the use of an adjuvant to achieve immunity. So far, few adjuvants have advanced successfully through clinical trials to become part of licensed vaccines. Vaxfectin® (Vical, CA, USA) represents a next-generation adjuvant with promise as a platform technology, showing utility with both plasmid DNA (pDNA) and protein-based vaccines. AREAS COVERED IN THIS REVIEW This review describes the chemical, physical, preclinical and clinical development of Vaxfectin for pDNA-based vaccines. Also included is the preclinical development of Vaxfectin-adjuvanted protein- and peptide-based vaccines. WHAT THE READER WILL GAIN The reader will gain knowledge of vaccine adjuvant development from bench to bedside. TAKE HOME MESSAGE Vaxfectin has effectively boosted the immune response against a range of pDNA-expressed pathogenic antigens in preclinical models extending from rodents to non-human primates. In the clinic, Vaxfectin-adjuvanted pDNA-based H5N1 influenza vaccines have been shown to be well tolerated and to result in durable immune responses within the predicted protective range reported for protein-based vaccines.
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Affiliation(s)
- Sean M Sullivan
- Vical, Inc., Pharmaceutical Sciences, 10390 Pacific Center Court, San Diego, CA 92121, USA.
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Shuaibu MN, Cherif MS, Kurosaki T, Helegbe GK, Kikuchi M, Yanagi T, Sasaki H, Hirayama K. Effect of nanoparticle coating on the immunogenicity of plasmid DNA vaccine encoding P. yoelii MSP-1 C-terminal. Vaccine 2011; 29:3239-47. [PMID: 21354479 DOI: 10.1016/j.vaccine.2011.02.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 02/03/2011] [Accepted: 02/12/2011] [Indexed: 11/30/2022]
Abstract
In order to assess a new strategy for DNA vaccine formulation and delivery, plasmid encoding Plasmodium yoelii MSP-1 C-terminal was formulated with newly designed nanoparticle-an anionic ternary complex of polyethylenimine and γ-polyglutamic acid (pVAX-MSP-1/PEI/γ-PGA), and intravenously administered to C57BL/6 mice in four different doses, three times at 3-week interval. Antibody response as determined by ELISA, IFA and Western blot, was dose-dependent and subsequent challenge with 10(5)P. yoelii-infected red blood cells revealed 33-60% survival in repeated experiments at a dose of 80 μg pDNA/mouse. IgG subtypes and cytokine levels in the serum and culture supernatants of stimulated spleen cells were also measured. Antigen-specific IgG response provoked by the DNA vaccination was dominated by IgG1 and IgG2b. Although the elevation of IL-12p40 and IFN-γ was marginal (P≥0.354) in the coated group, interleukin-4 levels were significantly higher (P≥0.013) in the coated group than in the naked or control group, suggesting a predominant Th2-type CD4(+) T cell response. These results therefore, overall indicate the possibility of selection and optimization of DNA vaccine formulation for intravenous delivery and may be useful in designing a nanoparticle-coated DNA vaccine that could optimally elicit a desired antibody response for various disease conditions.
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Affiliation(s)
- M N Shuaibu
- Department of Immunogenetics, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
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Sedegah M, Rogers WO, Belmonte M, Belmonte A, Banania G, Patterson NB, Rusalov D, Ferrari M, Richie TL, Doolan DL. Vaxfectin® enhances both antibody and in vitro T cell responses to each component of a 5-gene Plasmodium falciparum plasmid DNA vaccine mixture administered at low doses. Vaccine 2010; 28:3055-65. [DOI: 10.1016/j.vaccine.2009.10.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Revised: 10/08/2009] [Accepted: 10/12/2009] [Indexed: 10/20/2022]
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Vilalta A, Shlapobersky M, Wei Q, Planchon R, Rolland A, Sullivan S. Analysis of biomarkers after intramuscular injection of Vaxfectin®-formulated hCMV gB plasmid DNA. Vaccine 2009; 27:7409-17. [DOI: 10.1016/j.vaccine.2009.08.075] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 08/10/2009] [Accepted: 08/21/2009] [Indexed: 11/26/2022]
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YE MING, WEI QUN, CARNER KRISTINR, DOUKAS JOHN, SULLIVAN SEAN, ROLLAND ALAIN, SMITH LARRYR, WLOCH MARYK. RAPID DEVELOPMENT OF A VAXFECTIN®-ADJUVANTED DNA VACCINE ENCODING PANDEMIC SWINE-ORIGIN INFLUENZA A VIRUS (H1N1) HEMAGGLUTININ. ACTA ACUST UNITED AC 2009. [DOI: 10.1142/s1568558609000084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Vaxfectin®-adjuvanted seasonal influenza protein vaccine: Correlation of systemic and local immunological markers with formulation parameters. Vaccine 2009; 27:6404-10. [DOI: 10.1016/j.vaccine.2009.06.087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Babiuk S, Babiuk LA, van Drunen Littel-van den Hurk S. Editorial: DNA Vaccination: A Simple Concept with Challenges Regarding Implementation. Int Rev Immunol 2009; 25:51-81. [PMID: 16818365 DOI: 10.1080/08830180600743008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Pan CH, Jimenez GS, Nair N, Wei Q, Adams RJ, Polack FP, Rolland A, Vilalta A, Griffin DE. Use of Vaxfectin adjuvant with DNA vaccine encoding the measles virus hemagglutinin and fusion proteins protects juvenile and infant rhesus macaques against measles virus. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2008; 15:1214-21. [PMID: 18524884 PMCID: PMC2519314 DOI: 10.1128/cvi.00120-08] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 05/06/2008] [Accepted: 05/21/2008] [Indexed: 11/20/2022]
Abstract
A measles virus vaccine for infants under 6 months of age would help control measles. DNA vaccines hold promise, but none has provided full protection from challenge. Codon-optimized plasmid DNAs encoding the measles virus hemagglutinin and fusion glycoproteins were formulated with the cationic lipid-based adjuvant Vaxfectin. In mice, antibody and gamma interferon (IFN-gamma) production were increased by two- to threefold. In macaques, juveniles vaccinated at 0 and 28 days with 500 microg of DNA intradermally or with 1 mg intramuscularly developed sustained neutralizing antibody and H- and F-specific IFN-gamma responses. Infant monkeys developed sustained neutralizing antibody and T cells secreting IFN-gamma and interleukin-4. Twelve to 15 months after vaccination, vaccinated monkeys were protected from an intratracheal challenge: viremia was undetectable by cocultivation and rashes did not appear, while two naïve monkeys developed viremia and rashes. The use of Vaxfectin-formulated DNA is a promising approach to the development of a measles vaccine for young infants.
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Affiliation(s)
- Chien-Hsiung Pan
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205, USA
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Danquah MK, Forde GM. Development of a pilot-scale bacterial fermentation for plasmid-based biopharmaceutical production using a stoichiometric medium. BIOTECHNOL BIOPROC E 2008. [DOI: 10.1007/s12257-007-0080-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Danquah MK, Forde GM. Growth Medium Selection and Its Economic Impact on Plasmid DNA Production. J Biosci Bioeng 2007; 104:490-7. [DOI: 10.1263/jbb.104.490] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Accepted: 09/27/2007] [Indexed: 11/17/2022]
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LeBlanc R, Vasquez Y, Hannaman D, Kumar N. Markedly enhanced immunogenicity of a Pfs25 DNA-based malaria transmission-blocking vaccine by in vivo electroporation. Vaccine 2007; 26:185-92. [PMID: 18054817 DOI: 10.1016/j.vaccine.2007.10.066] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Revised: 10/19/2007] [Accepted: 10/29/2007] [Indexed: 11/29/2022]
Abstract
Pfs25 is a promising target antigen for the development of a malaria transmission-blocking vaccine and prior research has demonstrated induction of high and functionally effective antibodies in mice with IM injection of Pfs25 encoding DNA plasmid. Likewise, Pfs25 DNA vaccine was immunogenic in rhesus macaques but required a protein boost to elicit significant transmission-blocking antibodies. The translation of these encouraging findings to human clinical trials has been impeded largely by the relatively poor immunogenicity of DNA plasmids in larger animals. In vivo electroporation (EP) has revealed significant enhancement of the potency of DNA plasmids. The results reported here compared the immunogenicity and functional transmission-blocking effects of immunization with DNA plasmid (25 microg) by the traditional IM route compared to coupling the IM injection (0.25, 2.5 and 25 microg doses) with in vivo EP. Significantly, a 0.25 microg dose of DNA plasmid, when administered with EP, induced antibody titers (1:160,000) and functional transmission-blocking effects that were equivalent to those achieved by a one hundred fold higher (25 microg) dose of DNA plasmid given without EP. At a 25.0 microg DNA dose with or without EP there was sufficient antigenic stimulation to result in effective antibody titers; however EP method yielded antibody titer of 1:1,280,000 as compared to only 1:160,000 titer without EP. This observed two log reduction in the amount of DNA plasmid required to induce significant transmission-blocking effects makes a compelling argument in favor of further evaluation of DNA vaccines by in vivo EP method in larger animals. Further experiments in non-human primates and eventually in phase I human trials will determine if the use of EP will induce effective and sustained malaria transmission-blocking effects at acceptable doses of plasmid DNA.
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Affiliation(s)
- Ralph LeBlanc
- Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
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Scheiblhofer S, Weiss R, Thalhamer J. Genetic vaccination approaches against malaria based on the circumsporozoite protein. Wien Klin Wochenschr 2006; 118:9-17. [PMID: 17131235 DOI: 10.1007/s00508-006-0676-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Malaria is the world's major parasitic disease, for which effective control measures are urgently needed. Despite considerable efforts, no successful vaccine against malaria has been developed so far. The method of DNA-based immunization offers the possibility to induce both antibody- and cell-mediated immune responses to a variety of antigens. The flexibility of the DNA vaccine technology permits the combination of several antigens from different developmental stages of the parasite's complicated life cycle. This review covers the development of DNA-based immunization against malaria from initial experiments in small animals to recently conducted clinical studies. Focusing on one of the best characterized malaria vaccine candidate antigens, the circumsporozoite protein, an overview of strategies to enhance vaccine efficacy is provided. Advanced application methods such as the gene gun technology or the needle-less jet injection device are described. As DNA vaccination represents a relatively new methodology, safety concerns associated with planned clinical applications are discussed. In summary, this novel type of vaccine has to be considered as a promising tool for future malaria vaccination strategies.
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Affiliation(s)
- Sandra Scheiblhofer
- Division of Allergy and Immunology, Department of Molecular Biology, University of Salzburg, Salzburg, Austria
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Protection against congenital cytomegalovirus (CMV) disease, conferred by a replication-disabled, bacterial artificial chromosome (BAC)-based DNA vaccine. Vaccine 2006; 24:6175-86. [PMID: 16879902 DOI: 10.1016/j.vaccine.2006.06.077] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Revised: 05/30/2006] [Accepted: 06/23/2006] [Indexed: 11/28/2022]
Abstract
It is unclear if protective immunity can be conferred by a cytomegalovirus (CMV) vaccine encoding a single protein subunit, or if multiple viral genes need to be targeted. Using the guinea pig model of congenital CMV infection, these studies examined the immunogenicity and efficacy of a DNA vaccine based on the guinea pig cytomegalovirus (GPCMV) genome cloned as a non-infectious BAC plasmid, modified by transposon insertion into the homolog of the HCMV tegument protein, UL48. Following vaccination of female Hartley guinea pigs with BAC DNA, adverse GPCMV-related pregnancy outcome were assessed after establishment of pregnancy, followed by GPCMV third-trimester challenge. Animals immunized with recombinant BACmid engendered anti-GPCMV antibodies by ELISA assay. Immunogenicity of BAC plasmid DNA was augmented by inclusion of the lipid adjuvant, DOTMA/DOPE, in the vaccine regimen. Among pups born to 12 control (sham-immunized) dams challenged with GPCMV in the third trimester, mortality was 23/35 (66%). In contrast, among evaluable pregnancy outcomes in pups born to 10 BAC-immunized pregnant dams, preconception immunization resulted in reduced pup mortality, to 10/34 pups (29%; p<0.005 versus control, Fisher's exact test). In addition, vaccinated dams had reduced viral load, compared to controls, as assessed by quantitative, real-time PCR.
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