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Tajudeen YA, Oladipo HJ, Yusuff SI, Abimbola SO, Abdulkadir M, Oladunjoye IO, Omotosho AO, Egbewande OM, Shittu HD, Yusuf RO, Ogundipe O, Muili AO, Afolabi AO, Dahesh SMA, Gameil MAM, El-Sherbini MS. A landscape review of malaria vaccine candidates in the pipeline. Trop Dis Travel Med Vaccines 2024; 10:19. [PMID: 39085983 PMCID: PMC11293096 DOI: 10.1186/s40794-024-00222-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 04/15/2024] [Indexed: 08/02/2024] Open
Abstract
BACKGROUND Globally, malaria continues to pose a major health challenge, with approximately 247 million cases of the illness and 627,000 deaths reported in 2021. However, the threat is particularly pronounced in sub-Saharan African countries, where pregnant women and children under the age of five face heightened vulnerability to the disease. As a result, the imperative to develop malaria vaccines especially for these vulnerable populations, remains crucial in the pursuit of malaria eradication. However, despite decades of research, effective vaccine development faces technical challenges, including the rapid spread of drug-resistant parasite strains, the complex parasite lifecycle, the development of liver hypnozoites with potential for relapse, and evasion of the host immune system. This review aims to discuss the different malaria vaccine candidates in the pipeline, highlighting different approaches used for adjuvating these candidates, their benefits, and outcomes, and summarizing the progress of these vaccine candidates under development. METHOD A comprehensive web-based search for peer-reviewed journal articles published in SCOPUS, MEDLINE (via PubMed), Science Direct, WHO, and Advanced Google Scholar databases was conducted from 1990 to May 2022. Context-specific keywords such as "Malaria", "Malaria Vaccine", "Malaria Vaccine Candidates", "Vaccine Development", "Vaccine Safety", "Clinical Trials", "mRNA Vaccines", "Viral Vector Vaccines", "Protein-based Vaccines", "Subunit Vaccines", "Vaccine Adjuvants", "Vaccine-induced Immune Responses", and "Immunogenicity" were emphatically considered. Articles not directly related to malaria vaccine candidates in preclinical and clinical stages of development were excluded. RESULTS Various approaches have been studied for malaria vaccine development, targeting different parasite lifecycle stages, including the pre-erythrocytic, erythrocytic, and sexual stages. The RTS, S/AS01 vaccine, the first human parasite vaccine reaching WHO-listed authority maturity level 4, has demonstrated efficacy in preventing clinical malaria in African children. However, progress was slow in introducing other safe, and feasible malaria vaccines through clinical trials . Recent studies highlight the potential effectiveness of combining pre-erythrocytic and blood-stage vaccines, along with the advantages of mRNA vaccines for prophylaxis and treatment, and nonstructural vaccines for large-scale production. CONCLUSION Malaria vaccine candidates targeting different lifecycle stages of the parasite range from chemoprophylaxis vaccination to cross-species immune protection. The use of a multi-antigen, multi-stage combinational vaccine is therefore essential in the context of global health. This demands careful understanding and critical consideration of the long-term multi-faceted interplay of immune interference, co-dominance, complementary immune response, molecular targets, and adjuvants affecting the overall vaccine-induced immune response. Despite challenges, advancements in clinical trials and vaccination technology offer promising possibilities for novel approaches in malaria vaccine development.
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Affiliation(s)
- Yusuf Amuda Tajudeen
- Department of Microbiology, Faculty of Life Sciences, University of Ilorin, P.M.B. 1515, Ilorin, 240003, Nigeria
- Department of Epidemiology and Medical Statistics, Faculty of Public Health, College of Medicine, University of Ibadan, P.M.B 5017 G.P.O, Ibadan, Oyo State, Nigeria
| | - Habeebullah Jayeola Oladipo
- Department of Microbiology, Faculty of Life Sciences, University of Ilorin, P.M.B. 1515, Ilorin, 240003, Nigeria
- Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, 240003, Nigeria
| | - Sodiq Inaolaji Yusuff
- Department of Medicine, Faculty of Clinical Sciences, Obafemi Awolowo University, Ibadan- Ife Rd, Ife, 220282, Osun State, Nigeria
| | - Samuel O Abimbola
- Cyprus International Institute of Environmental and Public Health, Cyprus University of Technology, Limassol, 3036, Cyprus
| | - Muritala Abdulkadir
- Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, 240003, Nigeria
| | - Iyiola Olatunji Oladunjoye
- Department of Microbiology, Faculty of Life Sciences, University of Ilorin, P.M.B. 1515, Ilorin, 240003, Nigeria
| | - Abass Olawale Omotosho
- Department of Microbiology, Faculty of Pure and Applied Sciences, Kwara State University, P.M.B 1530, Malete-Ilorin, Ilorin, Nigeria
| | | | | | - Rashidat Onyinoyi Yusuf
- Faculty of Pharmaceutical Sciences, University of Ilorin, P.M.B. 1515, Ilorin, 240003, Nigeria
| | - Oluwatosin Ogundipe
- Department of Epidemiology and Medical Statistics, Faculty of Public Health, College of Medicine, University of Ibadan, P.M.B 5017 G.P.O, Ibadan, Oyo State, Nigeria
| | - Abdulbasit Opeyemi Muili
- Faculty of Basic Medical Sciences, Ladoke Akintola University of Technology, P.M.B 4000, Ogbomosho, Oyo State, Nigeria
| | - Abdullateef Opeyemi Afolabi
- Faculty of Biomedical Sciences, Department of Microbiology and Immunology, Kampala International University, Bushenyi, Uganda.
| | - Salwa M A Dahesh
- Research Institute of Medical Entomology, General Organization for Teaching Hospitals and Institutes, GOTHI, Damietta, Egypt
| | | | - Mona Said El-Sherbini
- Department of Medical Parasitology, Faculty of Medicine, Cairo University, Cairo, 11562, Egypt
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Miura K, Flores-Garcia Y, Long CA, Zavala F. Vaccines and monoclonal antibodies: new tools for malaria control. Clin Microbiol Rev 2024; 37:e0007123. [PMID: 38656211 PMCID: PMC11237600 DOI: 10.1128/cmr.00071-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024] Open
Abstract
SUMMARYMalaria remains one of the biggest health problems in the world. While significant reductions in malaria morbidity and mortality had been achieved from 2000 to 2015, the favorable trend has stalled, rather significant increases in malaria cases are seen in multiple areas. In 2022, there were 249 million estimated cases, and 608,000 malaria-related deaths, mostly in infants and children aged under 5 years, globally. Therefore, in addition to the expansion of existing anti-malarial control measures, it is critical to develop new tools, such as vaccines and monoclonal antibodies (mAbs), to fight malaria. In the last 2 years, the first and second malaria vaccines, both targeting Plasmodium falciparum circumsporozoite proteins (PfCSP), have been recommended by the World Health Organization to prevent P. falciparum malaria in children living in moderate to high transmission areas. While the approval of the two malaria vaccines is a considerable milestone in vaccine development, they have much room for improvement in efficacy and durability. In addition to the two approved vaccines, recent clinical trials with mAbs against PfCSP, blood-stage vaccines against P. falciparum or P. vivax, and transmission-blocking vaccine or mAb against P. falciparum have shown promising results. This review summarizes the development of the anti-PfCSP vaccines and mAbs, and recent topics in the blood- and transmission-blocking-stage vaccine candidates and mAbs. We further discuss issues of the current vaccines and the directions for the development of next-generation vaccines.
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Affiliation(s)
- Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Yevel Flores-Garcia
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Malaria Research Institute, Baltimore, Maryland, USA
| | - Carole A Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Fidel Zavala
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Malaria Research Institute, Baltimore, Maryland, USA
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3
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Rando HM, Lordan R, Kolla L, Sell E, Lee AJ, Wellhausen N, Naik A, Kamil JP, Gitter A, Greene CS. The Coming of Age of Nucleic Acid Vaccines during COVID-19. mSystems 2023; 8:e0092822. [PMID: 36861992 PMCID: PMC10134841 DOI: 10.1128/msystems.00928-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
In the 21st century, several emergent viruses have posed a global threat. Each pathogen has emphasized the value of rapid and scalable vaccine development programs. The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has made the importance of such efforts especially clear. New biotechnological advances in vaccinology allow for recent advances that provide only the nucleic acid building blocks of an antigen, eliminating many safety concerns. During the COVID-19 pandemic, these DNA and RNA vaccines have facilitated the development and deployment of vaccines at an unprecedented pace. This success was attributable at least in part to broader shifts in scientific research relative to prior epidemics: the genome of SARS-CoV-2 was available as early as January 2020, facilitating global efforts in the development of DNA and RNA vaccines within 2 weeks of the international community becoming aware of the new viral threat. Additionally, these technologies that were previously only theoretical are not only safe but also highly efficacious. Although historically a slow process, the rapid development of vaccines during the COVID-19 crisis reveals a major shift in vaccine technologies. Here, we provide historical context for the emergence of these paradigm-shifting vaccines. We describe several DNA and RNA vaccines in terms of their efficacy, safety, and approval status. We also discuss patterns in worldwide distribution. The advances made since early 2020 provide an exceptional illustration of how rapidly vaccine development technology has advanced in the last 2 decades in particular and suggest a new era in vaccines against emerging pathogens. IMPORTANCE The SARS-CoV-2 pandemic has caused untold damage globally, presenting unusual demands on but also unique opportunities for vaccine development. The development, production, and distribution of vaccines are imperative to saving lives, preventing severe illness, and reducing the economic and social burdens caused by the COVID-19 pandemic. Although vaccine technologies that provide the DNA or RNA sequence of an antigen had never previously been approved for use in humans, they have played a major role in the management of SARS-CoV-2. In this review, we discuss the history of these vaccines and how they have been applied to SARS-CoV-2. Additionally, given that the evolution of new SARS-CoV-2 variants continues to present a significant challenge in 2022, these vaccines remain an important and evolving tool in the biomedical response to the pandemic.
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Affiliation(s)
- Halie M. Rando
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz School of Medicine, Aurora, Colorado, USA
- Center for Health AI, University of Colorado Anschutz School of Medicine, Aurora, Colorado, USA
- Department of Biomedical Informatics, University of Colorado Anschutz School of Medicine, Aurora, Colorado, USA
| | - Ronan Lordan
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Likhitha Kolla
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Elizabeth Sell
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Alexandra J. Lee
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Nils Wellhausen
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Amruta Naik
- Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Jeremy P. Kamil
- Department of Microbiology and Immunology, Louisiana State University Health Sciences Center Shreveport, Shreveport, Louisiana, USA
| | - COVID-19 Review Consortium
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz School of Medicine, Aurora, Colorado, USA
- Center for Health AI, University of Colorado Anschutz School of Medicine, Aurora, Colorado, USA
- Department of Biomedical Informatics, University of Colorado Anschutz School of Medicine, Aurora, Colorado, USA
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Department of Microbiology and Immunology, Louisiana State University Health Sciences Center Shreveport, Shreveport, Louisiana, USA
- Department of Biostatistics and Medical Informatics, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Morgridge Institute for Research, Madison, Wisconsin, USA
- Childhood Cancer Data Lab, Alex’s Lemonade Stand Foundation, Philadelphia, Pennsylvania, USA
| | - Anthony Gitter
- Department of Biostatistics and Medical Informatics, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Morgridge Institute for Research, Madison, Wisconsin, USA
| | - Casey S. Greene
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz School of Medicine, Aurora, Colorado, USA
- Center for Health AI, University of Colorado Anschutz School of Medicine, Aurora, Colorado, USA
- Department of Biomedical Informatics, University of Colorado Anschutz School of Medicine, Aurora, Colorado, USA
- Childhood Cancer Data Lab, Alex’s Lemonade Stand Foundation, Philadelphia, Pennsylvania, USA
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Rando HM, Lordan R, Kolla L, Sell E, Lee AJ, Wellhausen N, Naik A, Kamil JP. The Coming of Age of Nucleic Acid Vaccines during COVID-19. ARXIV 2023:arXiv:2210.07247v2. [PMID: 36263086 PMCID: PMC9580386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In the 21st century, several emergent viruses have posed a global threat. Each pathogen has emphasized the value of rapid and scalable vaccine development programs. The ongoing SARS-CoV-2 pandemic has made the importance of such efforts especially clear. New biotechnological advances in vaccinology allow for recent advances that provide only the nucleic acid building blocks of an antigen, eliminating many safety concerns. During the COVID-19 pandemic, these DNA and RNA vaccines have facilitated the development and deployment of vaccines at an unprecedented pace. This success was attributable at least in part to broader shifts in scientific research relative to prior epidemics; the genome of SARS-CoV-2 was available as early as January 2020, facilitating global efforts in the development of DNA and RNA vaccines within two weeks of the international community becoming aware of the new viral threat. Additionally, these technologies that were previously only theoretical are not only safe but also highly efficacious. Although historically a slow process, the rapid development of vaccines during the COVID-19 crisis reveals a major shift in vaccine technologies. Here, we provide historical context for the emergence of these paradigm-shifting vaccines. We describe several DNA and RNA vaccines and in terms of their efficacy, safety, and approval status. We also discuss patterns in worldwide distribution. The advances made since early 2020 provide an exceptional illustration of how rapidly vaccine development technology has advanced in the last two decades in particular and suggest a new era in vaccines against emerging pathogens.
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Affiliation(s)
- Halie M Rando
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America; Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz School of Medicine, Aurora, Colorado, United States of America; Center for Health AI, University of Colorado Anschutz School of Medicine, Aurora, Colorado, United States of America; Department of Biomedical Informatics, University of Colorado Anschutz School of Medicine, Aurora, Colorado, United States of America
| | - Ronan Lordan
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-5158, USA; Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania; Philadelphia, PA 19104, USA
| | - Likhitha Kolla
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Elizabeth Sell
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Alexandra J Lee
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Nils Wellhausen
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Amruta Naik
- Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Jeremy P Kamil
- Department of Microbiology and Immunology, Louisiana State University Health Sciences Center Shreveport, Shreveport, Louisiana, USA
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5
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Sun Y, Shi X, Lu F, Fu H, Yin Y, Xu J, Jin C, Han ET, Huang X, Chen Y, Dong C, Cheng Y. Vesicular stomatitis virus-based vaccine targeting plasmodium blood-stage antigens elicits immune response and protects against malaria with protein booster strategy. Front Microbiol 2022; 13:1042414. [PMID: 36504817 PMCID: PMC9731671 DOI: 10.3389/fmicb.2022.1042414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 11/07/2022] [Indexed: 11/25/2022] Open
Abstract
Merozoite invasion of the erythrocytes in humans is a key step in the pathogenesis of malaria. The proteins involved in the merozoite invasion could be potential targets for the development of malaria vaccines. Novel viral-vector-based malaria vaccine regimens developed are currently under clinical trials. Vesicular stomatitis virus (VSV) is a single-stranded negative-strand RNA virus widely used as a vector for virus or cancer vaccines. Whether the VSV-based malarial vaccine is more effective than conventional vaccines based on proteins involved in parasitic invasion is still unclear. In this study, we have used the reverse genetics system to construct recombinant VSVs (rVSVs) expressing apical membrane protein 1 (AMA1), rhoptry neck protein 2 (RON2), and reticulocyte-binding protein homolog 5 (RH5), which are required for Plasmodium falciparum invasion. Our results showed that VSV-based viral vaccines significantly increased Plasmodium-specific IgG levels and lymphocyte proliferation. Also, VSV-PyAMA1 and VSV-PyRON2sp prime-boost regimens could significantly increase the levels of IL-2 and IFN-γ-producing by CD4+ and CD8+ T cells and suppress invasion in vitro. The rVSV prime-protein boost regimen significantly increase Plasmodium antigen-specific IgG levels in the serum of mice compared to the homologous rVSV prime-boost. Furthermore, the protective efficacy of rVSV prime protein boost immunization in the mice challenged with P. yoelii 17XL was better compared to traditional antigen immunization. Together, our results show that VSV vector is a novel strategy for malarial vaccine development and preventing the parasitic diseases.
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Affiliation(s)
- Yifan Sun
- Department of Laboratory Medicine, Affiliated Hospital of Jiangnan University, Wuxi, Jiangsu, China,Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Xiaodan Shi
- Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Feng Lu
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China
| | - Haitian Fu
- Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China,Department of Nuclear Medicine, Affiliated Hospital of Jiangnan University, Wuxi, Jiangsu, China
| | - Yi Yin
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China
| | - Jiahui Xu
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China
| | - Cheng Jin
- Department of Hepatobiliary Surgery, Affiliated Hospital of Jiangnan University, Wuxi, Jiangsu, China
| | - Eun-taek Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, South Korea
| | - Xuan Huang
- Department of Laboratory Medicine, Affiliated Hospital of Jiangnan University, Wuxi, Jiangsu, China
| | - Yongquan Chen
- Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Chunsheng Dong
- Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu, China,*Correspondence: Chunsheng Dong,
| | - Yang Cheng
- Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China,Yang Cheng,
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Lacey C, Musa A, Khalil ET, Younis B, Osman M, Wiggins R, Keding A, Kaye P. LEISH2b - A phase 2b study to assess the safety, efficacy, and immunogenicity of the Leishmania vaccine ChAd63-KH in post-kala azar dermal leishmaniasis. Wellcome Open Res 2022; 7:200. [PMID: 37252616 PMCID: PMC10213822 DOI: 10.12688/wellcomeopenres.17951.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2022] [Indexed: 01/16/2024] Open
Abstract
Background: The leishmaniases are neglected tropical diseases caused by various Leishmania parasite species transmitted by sand flies. They comprise a number of systemic and cutaneous syndromes including kala-azar (visceral leishmaniasis, VL), cutaneous leishmaniasis (CL), and post-kala-azar dermal leishmaniasis (PKDL). The leishmaniases cause significant mortality (estimated 20 - 50,000 deaths annually), morbidity, psychological sequelae, and healthcare and societal costs. Treatment modalities remain difficult. E.g., East African PKDL requires 20 days of intravenous therapy, and frequently relapsing VL is seen in the setting of HIV and immunodeficiency. We developed a new therapeutic vaccine, ChAd63-KH for VL / CL / PKDL and showed it to be safe and immunogenic in a phase 1 trial in the UK, and in a phase 2a trial in PKDL patients in Sudan. Methods: This is a randomised double-blind placebo-controlled phase 2b trial to assess the therapeutic efficacy and safety of ChAd63-KH in patients with persistent PKDL in Sudan. 100 participants will be randomly assigned 1:1 to receive placebo or ChAd63-KH (7.5 x10 10vp i.m.) at a single time point. Follow up is for 120 days after dosing and we will compare the clinical evolution of PKDL, as well as the humoral and cellular immune responses between the two arms. Discussion: Successful development of a therapeutic vaccine for leishmaniasis would have wide-ranging direct and indirect healthcare benefits that could be realized rapidly. For PKDL patients, an effective therapeutic vaccination used alone would have very significant clinical value, reducing the need for extensive hospitalization and chemotherapy. Combining vaccine with drug (immuno-chemotherapy) might significantly increase the effective life of new drugs, with lower dose / abbreviated regimens helping to limit the emergence of drug resistance. If therapeutic benefit of ChAd63-KH can be shown in PKDL further evaluation of the vaccine in other forms of leishmaniasis should be considered. Clinicaltrials.gov registration: NCT03969134.
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Affiliation(s)
- Charles Lacey
- York Biomedical Research Institute, University of York, UK, York, UK
| | - Ahmed Musa
- Institute of Endemic Diseases, University of Khartoum, Khartoum, Sudan
| | - El Tahir Khalil
- Institute of Endemic Diseases, University of Khartoum, Khartoum, Sudan
| | - Brima Younis
- Institute of Endemic Diseases, University of Khartoum, Khartoum, Sudan
| | - Mohamed Osman
- York Biomedical Research Institute, University of York, UK, York, UK
| | - Rebecca Wiggins
- York Biomedical Research Institute, University of York, UK, York, UK
| | - Ada Keding
- York Trials Unit, University of York, UK, York, UK
| | - Paul Kaye
- York Biomedical Research Institute, University of York, UK, York, UK
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7
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Bezbaruah R, Borah P, Kakoti BB, Al-Shar’I NA, Chandrasekaran B, Jaradat DMM, Al-Zeer MA, Abu-Romman S. Developmental Landscape of Potential Vaccine Candidates Based on Viral Vector for Prophylaxis of COVID-19. Front Mol Biosci 2021; 8:635337. [PMID: 33937326 PMCID: PMC8082173 DOI: 10.3389/fmolb.2021.635337] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/05/2021] [Indexed: 12/18/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2, SARS-CoV-2, arose at the end of 2019 as a zoonotic virus, which is the causative agent of the novel coronavirus outbreak COVID-19. Without any clear indications of abatement, the disease has become a major healthcare threat across the globe, owing to prolonged incubation period, high prevalence, and absence of existing drugs or vaccines. Development of COVID-19 vaccine is being considered as the most efficient strategy to curtail the ongoing pandemic. Following publication of genetic sequence of SARS-CoV-2, globally extensive research and development work has been in progress to develop a vaccine against the disease. The use of genetic engineering, recombinant technologies, and other computational tools has led to the expansion of several promising vaccine candidates. The range of technology platforms being evaluated, including virus-like particles, peptides, nucleic acid (DNA and RNA), recombinant proteins, inactivated virus, live attenuated viruses, and viral vectors (replicating and non-replicating) approaches, are striking features of the vaccine development strategies. Viral vectors, the next-generation vaccine platforms, provide a convenient method for delivering vaccine antigens into the host cell to induce antigenic proteins which can be tailored to arouse an assortment of immune responses, as evident from the success of smallpox vaccine and Ervebo vaccine against Ebola virus. As per the World Health Organization, till January 22, 2021, 14 viral vector vaccine candidates are under clinical development including 10 nonreplicating and four replicating types. Moreover, another 39 candidates based on viral vector platform are under preclinical evaluation. This review will outline the current developmental landscape and discuss issues that remain critical to the success or failure of viral vector vaccine candidates against COVID-19.
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Affiliation(s)
- Rajashri Bezbaruah
- Department of Pharmaceutical Sciences, Faculty of Science and Engineering, Dibrugarh University, Dibrugarh, India
| | - Pobitra Borah
- School of Pharmacy, Graphic Era Hill University, Dehradun, India
| | - Bibhuti Bhushan Kakoti
- Department of Pharmaceutical Sciences, Faculty of Science and Engineering, Dibrugarh University, Dibrugarh, India
| | - Nizar A. Al-Shar’I
- Department of Medicinal Chemistry and Pharmacognosy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, Jordan
| | | | - Da’san M. M. Jaradat
- Department of Chemistry, Faculty of Science, Al-Balqa Applied University, Al-Salt, Jordan
| | - Munir A. Al-Zeer
- Department of Applied Biochemistry, Institute of Biotechnology, Technical University of Berlin, Berlin, Germany
| | - Saeid Abu-Romman
- Department of Biotechnology, Faculty of Agricultural Technology, Al-Balqa Applied University, Al-Salt, Jordan
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8
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McGuire KA, Miura K, Wiethoff CM, Williamson KC. New adenovirus-based vaccine vectors targeting Pfs25 elicit antibodies that inhibit Plasmodium falciparum transmission. Malar J 2017; 16:254. [PMID: 28619071 PMCID: PMC5471885 DOI: 10.1186/s12936-017-1896-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 06/06/2017] [Indexed: 01/13/2023] Open
Abstract
Background An effective malaria transmission-blocking vaccine (TBV) would be a major advance in the current efforts to eliminate and, ultimately, eradicate malaria. Antibodies against Plasmodium falciparum surface protein, Pfs25, are known to block parasite development in the mosquito vector. However, in initial clinical trials the limited immunogenicity of recombinant Pfs25 protein-in-adjuvant vaccines has been a challenge. Methods Novel human adenovirus type 5 (Ad5) vectors were used in heterologous prime boost vaccination strategies to augment the immune response against Pfs25. Specifically, an Ad5 vector that directs expression of full-length, membrane-bound Pfs25 was used as a priming immunization followed by a boost with Ad5 viral particles displaying only the Pfs25 epitope targeted by transmission-blocking antibodies 4B7 and 1D2 (Pfs25 aa 122–134) in hypervariable region 5 of the hexon capsid protein. Results This heterologous prime-boost vaccine strategy induced antibodies that significantly inhibit P. falciparum transmission to mosquitoes in a standard membrane-feeding assay. Further, immunized mice generated a robust anti-Pfs25 antibody response characterized by higher titer, higher relative avidity and a broader IgG subclass profile than observed with a homologous prime-boost with recombinant Pfs25/alum. Conclusion The data suggest that focusing the immune response against defined epitopes displayed on the viral capsid is an effective strategy for transmission-blocking vaccine development.
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Affiliation(s)
- Kathleen A McGuire
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, 60153, USA. .,Abbvie, 1 North Waukegan Road, North Chicago, IL, 60064, USA.
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Christopher M Wiethoff
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, 60153, USA.,Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, 46285, USA
| | - Kim C Williamson
- Department of Microbiology and Immunology, Uniformed Services University, Bethesda, MD, 20814, USA
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Acosta-Ramirez E, Tram C, Kampen RM, Tillman MR, Schwendener RA, Xing Z, Halperin SA, Wang J. Respiratory macrophages regulate CD4 T memory responses to mucosal immunization with recombinant adenovirus-based vaccines. Cell Immunol 2016; 310:53-62. [PMID: 27425590 PMCID: PMC7094387 DOI: 10.1016/j.cellimm.2016.07.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 07/11/2016] [Accepted: 07/11/2016] [Indexed: 01/09/2023]
Abstract
Respiratory macrophages have dual functional roles that regulate CD4 T cell responses to recombinant adenovirus-based vaccination in a stage-dependent manner. Respiratory macrophages suppress the initial CD4 T cell activation and the subsequent size of tissue-resident CD4 memory T cells. Respiratory macrophages and potentially circulating monocytes are critically required for the development and fitness of long-term tissue-resident CD4 memory T cells.
Respiratory immunization is an attractive way to generate systemic and mucosal protective memory responses that are required for preventing mucosally transmitted infections. However, the molecular and cellular mechanisms for controlling memory T cell responses remain incompletely understood. In this study, we investigated the role of respiratory macrophage (MΦ) in regulating CD4 T cell responses to recombinant adenovirus-based (rAd) vaccines. We demonstrated that rAd intranasal (i.n.) vaccination induced migration and accumulation of respiratory MΦ and circulatory monocytes in the mediastinal lymph nodes and lung parenchyma. Under the influence of respiratory MΦ CD4 T cells exhibited slow proliferation kinetics and an increased tendency of generating central memory, as opposed to effector memory, CD4 T cell responses in vitro and in vivo. Correspondingly, depletion of MΦ using clodronate-containing liposome prior to i.n. immunization significantly enhanced CD4 T cell proliferation and increased the frequency of CD4 memory T cells in the airway lumen, demonstrating that MΦ initially serve as a negative regulator in limiting generation of mucosal tissue-resident memory CD4 T cells. However, clodronate-containing liposome delivery following i.n. immunization markedly reduced the frequencies of memory CD4 T cells in the airway lumen and spleen, indicating that respiratory MΦ and potentially circulating monocytes are critically required for maintaining long-term memory CD4 T cells. Collectively, our data demonstrate that rAd-induced mucosal CD4 T memory responses are regulated by respiratory MΦ and/or monocytes at multiple stages.
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Affiliation(s)
- Elizabeth Acosta-Ramirez
- Canadian Center for Vaccinology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada; Department of Microbiology & Immunology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada
| | - Cynthia Tram
- Canadian Center for Vaccinology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada; Department of Microbiology & Immunology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada
| | - Rachel M Kampen
- Canadian Center for Vaccinology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada; Department of Microbiology & Immunology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada
| | - Melanie R Tillman
- Canadian Center for Vaccinology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada; Department of Microbiology & Immunology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada
| | - Reto A Schwendener
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Zhou Xing
- McMaster Immunology Research Centre, McMaster University, Hamilton, ON, Canada
| | - Scott A Halperin
- Canadian Center for Vaccinology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada; Department of Microbiology & Immunology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada; Department of Pediatrics, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada
| | - Jun Wang
- Canadian Center for Vaccinology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada; Department of Microbiology & Immunology, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada; Department of Pediatrics, Faculty of Medicine, Dalhousie University, and IWK Health Centre, Halifax, Nova Scotia, Canada.
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Kallel H, Kamen AA. Large-scale adenovirus and poxvirus-vectored vaccine manufacturing to enable clinical trials. Biotechnol J 2015; 10:741-7. [PMID: 25914340 DOI: 10.1002/biot.201400390] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 03/03/2015] [Accepted: 04/13/2015] [Indexed: 12/11/2022]
Abstract
Efforts to make vaccines against infectious diseases and immunotherapies for cancer have evolved to utilize a variety of heterologous expression systems such as viral vectors. These vectors are often attenuated or engineered to safely deliver genes encoding antigens of different pathogens. Adenovirus and poxvirus vectors are among the viral vectors that are most frequently used to develop prophylactic vaccines against infectious diseases as well as therapeutic cancer vaccines. This mini-review describes the trends and processes in large-scale production of adenovirus and poxvirus vectors to meet the needs of clinical applications. We briefly describe the general principles for the production and purification of adenovirus and poxvirus viral vectors. Currently, adenovirus and poxvirus vector manufacturing methods rely on well-established cell culture technologies. Several improvements have been evaluated to increase the yield and to reduce the overall manufacturing cost, such as cultivation at high cell densities and continuous downstream processing. Additionally, advancements in vector characterization will greatly facilitate the development of novel vectored vaccine candidates.
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Affiliation(s)
- Héla Kallel
- Laboratory of Molecular Microbiology Vaccinology and Biotechnology Development, Viral Vaccines R&D Unit. Institut Pasteur de Tunis, Tunis, Tunisia
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Marty RR, Knuchel MC, Morin TNA, Naim HY. An immune competent mouse model for the characterization of recombinant measles vaccines. Hum Vaccin Immunother 2014; 11:83-90. [PMID: 25483519 DOI: 10.4161/hv.34358] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Today, immune compromised interferon-α-receptor deficient mice expressing hCD46 (IFNARCD46tg) are usually used for measles virus (MV) based vaccine characterization. However, for the development of MV-based recombinant vaccine candidates (rMV), an immune competent mouse model is desirable in order to induce and evaluate meaningful immune response. In this study, humoral and cellular immune response induced by rMV in immune competent mice expressing human MV receptor CD46 (hCD46tg) were compared with those induced in wild-type black/6, and IFNARCD46tg mice. All three strains developed humoral and cellular response against MV, whereas only hCD46tg and IFNARCD46tg mice developed a humoral response against the transgene. Differences were observed in the magnitude of the response, where the IFNARCD46tg mice displayed the strongest immune responses, followed by the hCD46tg mice and the black/6 mice. Interestingly, hCD46tg and wt black/6 mice showed a predominant CD4(+) T-cell response against MV-N, whereas IFNARCD46tg mice developed both, CD4(+) and CD8(+) T-cell response against MV-N. Analysis of the cytokine profile of MV-N specific CD4(+) T-cells and transgene (SIVgag) specific CD8(+) T-cells revealed qualitative differences of the T-cell responses; noticeably a significant reduction of the frequency of CD4(+)IL-2(+) expressing cells in IFNARCD46tg mice as compared with hCD46tg or wt black/6 mice. We show in this study significant quantitative and qualitative differences in immune responses between immune competent and immune-compromised mice. Our results therefore highlight the importance of the animal model and support the use of hCD46tg mice as mouse model for the characterization of the immunological profile induced by recombinant measles virus vaccine candidates.
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Abstract
PURPOSE OF REVIEW To briefly describe some of the replication-competent vectors being investigated for development of candidate HIV vaccines focusing primarily on technologies that have advanced to testing in macaques or have entered clinical trials. RECENT FINDINGS Replication-competent viral vectors have advanced to the stage at which decisions can be made regarding the future development of HIV vaccines. The viruses being used as replication-competent vector platforms vary considerably, and their unique attributes make it possible to test multiple vaccine design concepts and also mimic various aspects of an HIV infection. Replication-competent viral vectors encoding simian immunodeficiency virus or HIV proteins can be used to safely immunize macaques, and in some cases, there is evidence of significant vaccine efficacy in challenge protection studies. Several live HIV vaccine vectors are in clinical trials to evaluate immunogenicity, safety, the effect of mucosal delivery, and potential effects of preexisting immunity. SUMMARY A variety of DNA and RNA viruses are being used to develop replication-competent viral vectors for HIV vaccine delivery. Multiple viral vector platforms have proven to be well tolerated and immunogenic with evidence of efficacy in macaques. Some of the more advanced HIV vaccine prototypes based on vesicular stomatitis virus, vaccinia virus, measles virus, and Sendai virus are in clinical trials.
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Large-scale nucleotide optimization of simian immunodeficiency virus reduces its capacity to stimulate type I interferon in vitro. J Virol 2014; 88:4161-72. [PMID: 24478441 DOI: 10.1128/jvi.03223-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
UNLABELLED Lentiviral RNA genomes present a strong bias in their nucleotide composition with extremely high frequencies of A nucleotide in human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV). Based on the observation that human optimization of RNA virus gene fragments may abolish their ability to stimulate the type I interferon (IFN-I) response, we identified the most biased sequences along the SIV genome and showed that they are the most potent IFN-I stimulators. With the aim of designing an attenuated SIV genome based on a reduced capacity to activate the IFN-I response, we synthesized artificial SIV genomes whose biased sequences were optimized toward macaque average nucleotide composition without altering their regulatory elements or amino acid sequences. A synthetic SIV optimized with 169 synonymous mutations in gag and pol genes showed a 100-fold decrease in replicative capacity. Interestingly, a synthetic SIV optimized with 70 synonymous mutations in pol had a normal replicative capacity. Its ability to stimulate IFN-I was reduced when infected cells were cocultured with reporter cells. IFN regulatory factor 3 (IRF3) transcription factor was required for IFN-I stimulation, implicating cytosolic sensors in the detection of SIV-biased RNA in infected cells. No reversion of introduced mutations was observed for either of the optimized viruses after 10 serial passages. In conclusion, we have designed large-scale nucleotide-modified SIVs that may display attenuated pathogenic potential. IMPORTANCE In this study, we synthesized artificial SIV genomes in which the most hyperbiased sequences were optimized to bring them closer to the nucleotide composition of the macaque SIV host. Interestingly, we generated a stable synthetic SIV optimized with 70 synonymous mutations in pol gene, which had a normal replicative capacity but a reduced ability to stimulate type I IFN. This demonstrates the possibility to rationally change viral nucleotide composition to design replicative and genetically stable lentiviruses with attenuated pathogenic potentials.
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Malaria vaccine adjuvants: latest update and challenges in preclinical and clinical research. BIOMED RESEARCH INTERNATIONAL 2013; 2013:282913. [PMID: 23710439 PMCID: PMC3655447 DOI: 10.1155/2013/282913] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 03/21/2013] [Indexed: 12/11/2022]
Abstract
There is no malaria vaccine currently available, and the most advanced candidate has recently reported a modest 30% efficacy against clinical malaria. Although many efforts have been dedicated to achieve this goal, the research was mainly directed to identify antigenic targets. Nevertheless, the latest progresses on understanding how immune system works and the data recovered from vaccination studies have conferred to the vaccine formulation its deserved relevance. Additionally to the antigen nature, the manner in which it is presented (delivery adjuvants) as well as the immunostimulatory effect of the formulation components (immunostimulants) modulates the immune response elicited. Protective immunity against malaria requires the induction of humoral, antibody-dependent cellular inhibition (ADCI) and effector and memory cell responses. This review summarizes the status of adjuvants that have been or are being employed in the malaria vaccine development, focusing on the pharmaceutical and immunological aspects, as well as on their immunization outcomings at clinical and preclinical stages.
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Knuchel MC, Marty RR, Morin TNA, Ilter O, Zuniga A, Naim HY. Relevance of a pre-existing measles immunity prior immunization with a recombinant measles virus vector. Hum Vaccin Immunother 2013; 9:599-606. [PMID: 23324399 DOI: 10.4161/hv.23241] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Measles virus (MV) vectors are promising candidates for designing new recombinant vaccines since the parental live vaccines have a well-known safety and efficacy record. Like all viral vectors, the MV vector efficacy in inducing a protecting immune answer could be affected by the pre-existing immunity among the human population. In order to determine the optimal immunization route and regimen, we mimicked a MV pre-immunity by passively administrating MV neutralizing antibodies (MV-nAb) prior intramuscular (i.m.) and/or intranasal (i.n.) immunization with recombinant MV expressing the SIV-gag antigen (rMV-SIVgag). Our results revealed that 500 mIU of MV-nAb allowed the induction of a humoral and cellular immune response against the vector and the transgene, while higher titers of the MV-nAb were significantly inhibitory. In a prime-boost regimen, in the presence of MV-nAb, the intranasal-intramuscular (i.n.-i.m.) or intramuscular-intramuscular (i.m.-i.m.) routes induced higher humoral immune responses against the vector and the transgene (SIV-gag). In naive animals, cellular immune response was significantly higher by i.m. immunization; however, MV pre-immunity did not seem to affect the cellular immune response after an i.n. immunization. In summary, we show that a pre-existing immunity of up to 500 mIU anti-MV neutralizing antibodies had little effect on the replication of rMV and did not inhibit the induction of significant humoral and cellular immune responses in immune-competent mice.
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Irie T, Carnero E, García-Sastre A, Harty RN. In Vivo Replication and Pathogenesis of Vesicular Stomatitis Virus Recombinant M40 Containing Ebola Virus L-Domain Sequences. Infect Dis (Lond) 2012; 5:59-64. [PMID: 23794798 DOI: 10.4137/idrt.s10652] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The M40 VSV recombinant was engineered to contain overlapping PTAP and PPxY L-domain motifs and flanking residues from the VP40 protein of Ebola virus. Replication of M40 in cell culture is virtually indistinguishable from that of control viruses. However, the presence of the Ebola PTAP motif in the M40 recombinant enabled this virus to interact with and recruit host Tsg101, which was packaged into M40 virions. In this brief report, we compared replication and the pathogenic profiles of M40 and the parental virus M51R in mice to determine whether the presence of the Ebola L-domains and flanking residues altered in vivo characteristics of the virus. Overall, the in vivo characteristics of M40 were similar to those of the parental M51R virus, indicating that the Ebola sequences did not alter pathogenesis of VSV in this small animal model of infection.
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Affiliation(s)
- Takashi Irie
- Department of Virology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
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Josefsberg JO, Buckland B. Vaccine process technology. Biotechnol Bioeng 2012; 109:1443-60. [DOI: 10.1002/bit.24493] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 02/24/2012] [Accepted: 02/27/2012] [Indexed: 12/15/2022]
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Sedegah M, Tamminga C, McGrath S, House B, Ganeshan H, Lejano J, Abot E, Banania GJ, Sayo R, Farooq F, Belmonte M, Manohar N, Richie NO, Wood C, Long CA, Regis D, Williams FT, Shi M, Chuang I, Spring M, Epstein JE, Mendoza-Silveiras J, Limbach K, Patterson NB, Bruder JT, Doolan DL, King CR, Soisson L, Diggs C, Carucci D, Dutta S, Hollingdale MR, Ockenhouse CF, Richie TL. Adenovirus 5-vectored P. falciparum vaccine expressing CSP and AMA1. Part A: safety and immunogenicity in seronegative adults. PLoS One 2011; 6:e24586. [PMID: 22003383 PMCID: PMC3189181 DOI: 10.1371/journal.pone.0024586] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 08/15/2011] [Indexed: 11/24/2022] Open
Abstract
Background Models of immunity to malaria indicate the importance of CD8+ T cell responses for targeting intrahepatic stages and antibodies for targeting sporozoite and blood stages. We designed a multistage adenovirus 5 (Ad5)-vectored Plasmodium falciparum malaria vaccine, aiming to induce both types of responses in humans, that was tested for safety and immunogenicity in a Phase 1 dose escalation trial in Ad5-seronegative volunteers. Methodology/Principal Findings The NMRC-M3V-Ad-PfCA vaccine combines two adenovectors encoding circumsporozoite protein (CSP) and apical membrane antigen-1 (AMA1). Group 1 (n = 6) healthy volunteers received one intramuscular injection of 2×10∧10 particle units (1×10∧10 each construct) and Group 2 (n = 6) a five-fold higher dose. Transient, mild to moderate adverse events were more pronounced with the higher dose. ELISpot responses to CSP and AMA1 peaked at 1 month, were higher in the low dose (geomean CSP = 422, AMA1 = 862 spot forming cells/million) than in the high dose (CSP = 154, p = 0.049, AMA1 = 423, p = 0.045) group and were still positive at 12 months in a number of volunteers. ELISpot depletion assays identified dependence on CD4+ or on both CD4+ and CD8+ T cells, with few responses dependent only on CD8+ T cells. Intracellular cytokine staining detected stronger CD8+ than CD4+ T cell IFN-γ responses (CSP p = 0.0001, AMA1 p = 0.003), but similar frequencies of multifunctional CD4+ and CD8+ T cells secreting two or more of IFN-γ, TNF-α or IL-2. Median fluorescence intensities were 7–10 fold higher in triple than single secreting cells. Antibody responses were low but trended higher in the high dose group and did not inhibit growth of cultured P. falciparum blood stage parasites. Significance As found in other trials, adenovectored vaccines appeared safe and well-tolerated at doses up to 1×10∧11 particle units. This is the first demonstration in humans of a malaria vaccine eliciting strong CD8+ T cell IFN-γ responses. Trial Registration ClinicalTrials.govNCT00392015
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Affiliation(s)
- Martha Sedegah
- U.S. Military Malaria Vaccine Program, Naval Medical Research Center, Silver Spring, Maryland, United States of America.
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Almeida APMM, Bruna-Romero O. Synergism/complementarity of recombinant adenoviral vectors and other vaccination platforms during induction of protective immunity against malaria. Mem Inst Oswaldo Cruz 2011; 106 Suppl 1:193-201. [PMID: 21881774 DOI: 10.1590/s0074-02762011000900024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 06/15/2011] [Indexed: 12/19/2022] Open
Abstract
The lack of immunogenicity of most malaria antigens and the complex immune responses required for achieving protective immunity against this infectious disease have traditionally hampered the development of an efficient human malaria vaccine. The current boom in development of recombinant viral vectors and their use in prime-boost protocols that result in enhanced immune outcomes have increased the number of malaria vaccine candidates that access pre-clinical and clinical trials. In the frontline, adenoviruses and poxviruses seem to be giving the best immunization results in experimental animals and their mutual combination, or their combination with recombinant proteins (formulated in adjuvants and given in sequence or being given as protein/virus admixtures), has been shown to reach unprecedented levels of anti-malaria immunity that predictably will be somehow reproduced in the human setting. However, all this optimism was previously seen in the malaria vaccine development field without many real applicable results to date. We describe here the current state-of-the-art in the field of recombinant adenovirus research for malaria vaccine development, in particular referring to their use in combination with other immunogens in heterologous prime-boost protocols, while trying to simultaneously show our contributions and point of view on this subject.
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Porter DW, Thompson FM, Berthoud TK, Hutchings CL, Andrews L, Biswas S, Poulton I, Prieur E, Correa S, Rowland R, Lang T, Williams J, Gilbert SC, Sinden RE, Todryk S, Hill AVS. A human Phase I/IIa malaria challenge trial of a polyprotein malaria vaccine. Vaccine 2011; 29:7514-22. [PMID: 21501642 PMCID: PMC3195259 DOI: 10.1016/j.vaccine.2011.03.083] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 02/12/2011] [Accepted: 03/22/2011] [Indexed: 11/30/2022]
Abstract
We examined the safety, immunogenicity and efficacy of a prime-boost vaccination regime involving two poxvirus malaria subunit vaccines, FP9-PP and MVA-PP, expressing the same polyprotein consisting of six pre-erythrocytic antigens from Plasmodium falciparum. Following safety assessment of single doses, 15 volunteers received a heterologous prime-boost vaccination regime and underwent malaria sporozoite challenge. The vaccines were safe but interferon-γ ELISPOT responses were low compared to other poxvirus vectors, despite targeting multiple antigens. There was no vaccine efficacy as measured by delay in time to parasitaemia. A number of possible explanations are discussed, including the very large insert size of the polyprotein transgene.
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Affiliation(s)
- David W Porter
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Old Road, Oxford, OX3 7LJ, UK.
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Brun A, Bárcena J, Blanco E, Borrego B, Dory D, Escribano JM, Le Gall-Reculé G, Ortego J, Dixon LK. Current strategies for subunit and genetic viral veterinary vaccine development. Virus Res 2011; 157:1-12. [PMID: 21316403 DOI: 10.1016/j.virusres.2011.02.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 02/03/2011] [Accepted: 02/04/2011] [Indexed: 12/24/2022]
Abstract
Developing vaccines for livestock provides researchers with the opportunity to perform efficacy testing in the natural hosts. This enables the evaluation of different strategies, including definition of effective antigens or antigen combinations, and improvement in delivery systems for target antigens so that protective immune responses can be modulated or potentiated. An impressive amount of knowledge has been generated in recent years on vaccine strategies and consequently a wide variety of antigen delivery systems is now available for vaccine research. This paper reviews several antigen production and delivery strategies other than those based on the use of live viral vectors. Genetic and protein subunit vaccines as well as alternative production systems are considered in this review.
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Affiliation(s)
- Alejandro Brun
- Centro de Investigación en Sanidad Animal (CISA-INIA), Valdeolmos, 28130 Madrid, Spain.
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Adenovirus-vectored Plasmodium vivax ookinete surface protein, Pvs25, as a potential transmission-blocking vaccine. Vaccine 2011; 29:2720-6. [PMID: 21315699 DOI: 10.1016/j.vaccine.2011.01.083] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 12/29/2010] [Accepted: 01/21/2011] [Indexed: 11/22/2022]
Abstract
Adjuvants or delivery vehicles are essential components to expedite malaria vaccine development. In this study, replication-defective human adenovirus serotype 5 (rAd) was genetically engineered to express the Plasmodium vivax ookinete surface protein (OSP), Pvs25 (AdPvs25). BALB/c mice immunized with the AdPvs25 through various routes including intramuscular, subcutaneous and intranasal routes were analyzed for induction of antigen-specific transmission-blocking immunity. Parenteral but not mucosal immunization induced high serum immunoglobulin G (IgG) responses specific to P. vivax ookinetes isolated from P. vivax volunteer patients from Thailand. The membrane feeding assay revealed that antisera conferred a transmission blockade of up to 99% reduction in the average oocyst numbers per mosquito, while immunization with a rAd expressing Pfs25 from Plasmodium falciparum, a homolog of Pvs25, conferred only a background level of blockade, suggesting that a species-specific transmission-blocking immunity was induced. Vaccine efficacy of AdPvs25 was slightly higher than to a recombinant Pvs25 protein mixed with aluminum hydroxide, but less efficacious than the protein emulsified with incomplete Freund's adjuvant. This study, the first preclinical evaluation of adenovirus-vectored malaria OSPs, implicates a potential inclusion of malaria transmission-blocking vaccine antigens in viral vector systems.
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Hamid MMA, Remarque EJ, El Hassan IM, Hussain AA, Narum DL, Thomas AW, Kocken CHM, Weiss WR, Faber BW. Malaria infection by sporozoite challenge induces high functional antibody titres against blood stage antigens after a DNA prime, poxvirus boost vaccination strategy in Rhesus macaques. Malar J 2011; 10:29. [PMID: 21303498 PMCID: PMC3046915 DOI: 10.1186/1475-2875-10-29] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 02/08/2011] [Indexed: 11/22/2022] Open
Abstract
Background A DNA prime, poxvirus (COPAK) boost vaccination regime with four antigens, i.e. a combination of two Plasmodium knowlesi sporozoite (csp/ssp2) and two blood stage (ama1/msp142) genes, leads to self-limited parasitaemia in 60% of rhesus monkeys and survival from an otherwise lethal infection with P. knowlesi. In the present study, the role of the blood stage antigens in protection was studied in depth, focusing on antibody formation against the blood stage antigens and the functionality thereof. Methods Rhesus macaques were immunized with the four-component vaccine and subsequently challenged i.v. with 100 P. knowlesi sporozoites. During immunization and challenge, antibody titres against the two blood stage antigens were determined, as well as the in vitro growth inhibition capacity of those antibodies. Antigen reversal experiments were performed to determine the relative contribution of antibodies against each of the two blood stage antigens to the inhibition. Results After vaccination, PkAMA1 and PkMSP119 antibody titres in vaccinated animals were low, which was reflected in low levels of inhibition by these antibodies as determined by in vitro inhibition assays. Interestingly, after sporozoite challenge antibody titres against blood stage antigens were boosted over 30-fold in both protected and not protected animals. The in vitro inhibition levels increased to high levels (median inhibitions of 59% and 56% at 6 mg/mL total IgG, respectively). As growth inhibition levels were not significantly different between protected and not protected animals, the ability to control infection appeared cannot be explained by GIA levels. Judged by in vitro antigen reversal growth inhibition assays, over 85% of the inhibitory activity of these antibodies was directed against PkAMA1. Conclusions This is the first report that demonstrates that a DNA prime/poxvirus boost vaccination regimen induces low levels of malaria parasite growth inhibitory antibodies, which are boosted to high levels upon challenge. No association could, however, be established between the levels of inhibitory capacity in vitro and protection, either after vaccination or after challenge.
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Gamble LJ, Matthews QL. Current progress in the development of a prophylactic vaccine for HIV-1. DRUG DESIGN DEVELOPMENT AND THERAPY 2010; 5:9-26. [PMID: 21267356 PMCID: PMC3023272 DOI: 10.2147/dddt.s6959] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Since its discovery and characterization in the early 1980s as a virus that attacks the immune system, there has been some success for the treatment of human immunodeficiency virus-1 (HIV-1) infection. However, due to the overwhelming public health impact of this virus, a vaccine is needed urgently. Despite the tireless efforts of scientist and clinicians, there is still no safe and effective vaccine that provides sterilizing immunity. A vaccine that provides sterilizing immunity against HIV infection remains elusive in part due to the following reasons: 1) degree of diversity of the virus, 2) ability of the virus to evade the hosts' immunity, and 3) lack of appropriate animal models in which to test vaccine candidates. There have been several attempts to stimulate the immune system to provide protection against HIV-infection. Here, we will discuss attempts that have been made to induce sterilizing immunity, including traditional vaccination attempts, induction of broadly neutralizing antibody production, DNA vaccines, and use of viral vectors. Some of these attempts show promise pending continued research efforts.
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Affiliation(s)
- Lena J Gamble
- Department of Medicine, The Gene Therapy Center, University of Alabama at Birmingham, 35294, USA
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Matthews QL. Capsid-incorporation of antigens into adenovirus capsid proteins for a vaccine approach. Mol Pharm 2010; 8:3-11. [PMID: 21047139 DOI: 10.1021/mp100214b] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Some viral vectors are potent inducers of cellular and humoral responses; therefore, viral vectors can be used to vaccinate against cancer or infectious diseases. This report will focus on adenovirus (Ad)-based vectors. Traditional viral-vector vaccination embodies the concept that the vector uses the host-cell machinery to express antigens that are encoded as transgenes within the viral vector. Several preclinical successes have used this approach in animal model systems. However, in some instances, these conventional Ad-based vaccines have yielded suboptimal clinical results. These suboptimal results are ascribed, in part, to preexisting Ad serotype 5 (Ad5) immunity. To address this issue, the "antigen capsid-incorporation" strategy has been developed to circumvent the drawbacks associated with conventional transgene expression of antigens by Ad vectors. This strategy embodies the incorporation of antigenic peptides within the capsid structure of viral vectors. Incorporating immunogenic peptides into the Ad capsid offers potential advantages. Importantly, vaccination by means of the antigen capsid-incorporated approach results in a strong humoral response, similar to the response generated by native Ad capsid proteins. This strategy also allows for the boosting of antigenic specific responses. This strategy may be the way forward for improved vaccine schemes, especially for those infections requiring a strong humoral antigenic response.
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Affiliation(s)
- Qiana L Matthews
- Division of Human Gene Therapy, Departments of Medicine, Pathology, Surgery, Obstetrics and Gynecology, the Gene Therapy Center, and Center for AIDS Research, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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Brewoo JN, Powell TD, Stinchcomb DT, Osorio JE. Efficacy and safety of a modified vaccinia Ankara (MVA) vectored plague vaccine in mice. Vaccine 2010; 28:5891-9. [PMID: 20638759 DOI: 10.1016/j.vaccine.2010.06.054] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2010] [Revised: 05/04/2010] [Accepted: 06/16/2010] [Indexed: 01/29/2023]
Abstract
The efficacy and safety of plague vaccines based on the modified vaccinia Ankara (MVA) viral vector was evaluated. MVA recombinants were constructed expressing Yersinia pestis antigens under the translational control of the encephalomyocarditis virus (EMCV) internal ribosomal entry site (IRES) and/or fused to the tissue plasminogen activator (tPA) secretory signal. A MVA/Y. pestis recombinant that expressed a truncated version of the low-calcium response V antigen (MVA/IRES/tPA/V(307)), conferred significant protection (87.5-100%) against intranasal or intraperitoneal challenge with CO92 (encapsulated) or Java 9 (non-encapsulated) strains of Y. pestis, respectively. In contrast, a MVA/Y. pestis recombinant that expressed the full-length V antigen provided only 37.5% protection against challenge with CO92 or Java 9 strains, respectively. Interestingly, a MVA/Y. pestis recombinant that expressed the capsular protein (F1) did not elicit significant antibody titers but still conferred 50% and 25% protection against CO92 or Java 9 challenge, respectively. The MVA/Y. pestis recombinant viruses did not demonstrate any mortality or morbidity in SCID mice. Based on their safety and efficacy in mice, these MVA/Y. pestis recombinants are candidates for further development as biodefense and public health vaccines.
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Akondy RS, Monson ND, Miller JD, Edupuganti S, Teuwen D, Wu H, Quyyumi F, Garg S, Altman JD, Del Rio C, Keyserling HL, Ploss A, Rice CM, Orenstein WA, Mulligan MJ, Ahmed R. The yellow fever virus vaccine induces a broad and polyfunctional human memory CD8+ T cell response. THE JOURNAL OF IMMUNOLOGY 2010; 183:7919-30. [PMID: 19933869 DOI: 10.4049/jimmunol.0803903] [Citation(s) in RCA: 255] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The live yellow fever vaccine (YF-17D) offers a unique opportunity to study memory CD8(+) T cell differentiation in humans following an acute viral infection. We have performed a comprehensive analysis of the virus-specific CD8(+) T cell response using overlapping peptides spanning the entire viral genome. Our results showed that the YF-17D vaccine induces a broad CD8(+) T cell response targeting several epitopes within each viral protein. We identified a dominant HLA-A2-restricted epitope in the NS4B protein and used tetramers specific for this epitope to track the CD8(+) T cell response over a 2 year period. This longitudinal analysis showed the following. 1) Memory CD8(+) T cells appear to pass through an effector phase and then gradually down-regulate expression of activation markers and effector molecules. 2) This effector phase was characterized by down-regulation of CD127, Bcl-2, CCR7, and CD45RA and was followed by a substantial contraction resulting in a pool of memory T cells that re-expressed CD127, Bcl-2, and CD45RA. 3) These memory cells were polyfunctional in terms of degranulation and production of the cytokines IFN-gamma, TNF-alpha, IL-2, and MIP-1beta. 4) The YF-17D-specific memory CD8(+) T cells had a phenotype (CCR7(-)CD45RA(+)) that is typically associated with terminally differentiated cells with limited proliferative capacity (T(EMRA)). However, these cells exhibited robust proliferative potential showing that expression of CD45RA may not always associate with terminal differentiation and, in fact, may be an indicator of highly functional memory CD8(+) T cells generated after acute viral infections.
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Affiliation(s)
- Rama S Akondy
- Emory Vaccine Center and the Hope Clinic, Emory University School of Medicine, Atlanta, GA 30022, USA
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Kaba SA, Brando C, Guo Q, Mittelholzer C, Raman S, Tropel D, Aebi U, Burkhard P, Lanar DE. A nonadjuvanted polypeptide nanoparticle vaccine confers long-lasting protection against rodent malaria. THE JOURNAL OF IMMUNOLOGY 2009; 183:7268-77. [PMID: 19915055 DOI: 10.4049/jimmunol.0901957] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We have designed and produced a prototypic malaria vaccine based on a highly versatile self-assembling polypeptide nanoparticle (SAPN) platform that can repetitively display antigenic epitopes. We used this platform to display a tandem repeat of the B cell immunodominant repeat epitope (DPPPPNPN)(2)D of the malaria parasite Plasmodium berghei circumsporozoite protein. Administered in saline, without the need for a heterologous adjuvant, the SAPN construct P4c-Mal conferred a long-lived, protective immune response to mice with a broad range of genetically distinct immune backgrounds including the H-2(b), H-2(d), and H-2(k) alleles. Immunized mice produced a CD4(+) T cell-dependent, high-titer, long-lasting, high-avidity Ab response against the B cell epitope. Mice were protected against an initial challenge of parasites up to 6 mo after the last immunization or for up to 15 mo against a second challenge after an initial challenge of parasites had successfully been cleared. Furthermore, we demonstrate that the SAPN platform not only functions to deliver an ordered repetitive array of B cell peptide epitopes but operates as a classical immunological carrier to provide cognate help to the P4c-Mal-specific B cells.
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Affiliation(s)
- Stephen A Kaba
- Division of Malaria Vaccine Development, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
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Abstract
Traditional vaccine technologies have resulted in an impressive array of efficacious vaccines against a variety of infectious agents. However, several potentially deadly pathogens, including retroviruses and parasites, have proven less amenable to the application of traditional vaccine platforms, indicating the need for new approaches. Viral vectors represent an attractive way to deliver and present vaccine antigens that may offer advantages over traditional platforms. Due to their ability to induce strong cell-mediated immunity (CMI) in addition to antibodies, viral vectors may be suitable for infectious agents, such as malaria parasites, where potent CMI is required for protection. Poxvirus-vectored malaria vaccines have been the most extensively studied in the clinic, achieving significant reductions in liver-stage parasite burden. More recently, adenovirus-vectored malaria vaccines have entered clinical testing. The most promising approach - heterologous prime-boost regimens, in which different viral vectors are sequentially paired with each other or with DNA or recombinant protein vaccines - is now being explored, and could provide high-grade protection, if findings in animal models are translatable to humans. Significant barriers remain, however, such as pre-existing immunity to the vector particle and an unexplained safety signal observed in one trial suggesting an increased risk of HIV acquisition in volunteers with pre-existing immunity to the vector.
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Affiliation(s)
- K J Limbach
- U.S. Military Malaria Vaccine Program, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910-7500, USA.
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Persistence of transgene expression influences CD8+ T-cell expansion and maintenance following immunization with recombinant adenovirus. J Virol 2009; 83:12027-36. [PMID: 19759135 DOI: 10.1128/jvi.00593-09] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Previous studies determined that the CD8(+) T-cell response elicited by recombinant adenovirus exhibited a protracted contraction phase that was associated with long-term presentation of antigen. To gain further insight into this process, a doxycycline-regulated adenovirus was constructed to enable controlled extinction of transgene expression in vivo. We investigated the impact of premature termination of transgene expression at various time points (day 3 to day 60) following immunization. When transgene expression was terminated before the maximum response had been attained, overall expansion was attenuated, yielding a small memory population. When transgene expression was terminated between day 13 and day 30, the memory population was not sustained, demonstrating that the early memory population was antigen dependent. Extinction of transgene expression at day 60 had no obvious impact on memory maintenance, indicating that maintenance of the memory population may ultimately become independent of transgene expression. Premature termination of antigen expression had significant but modest effects on the phenotype and cytokine profile of the memory population. These results offer new insights into the mechanisms of memory CD8(+) T-cell maintenance following immunization with a recombinant adenovirus.
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Jiang G, Shi M, Conteh S, Richie N, Banania G, Geneshan H, Valencia A, Singh P, Aguiar J, Limbach K, Kamrud KI, Rayner J, Smith J, Bruder JT, King CR, Tsuboi T, Takeo S, Endo Y, Doolan DL, Richie TL, Weiss WR. Sterile protection against Plasmodium knowlesi in rhesus monkeys from a malaria vaccine: comparison of heterologous prime boost strategies. PLoS One 2009; 4:e6559. [PMID: 19668343 PMCID: PMC2720458 DOI: 10.1371/journal.pone.0006559] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Accepted: 06/06/2009] [Indexed: 11/18/2022] Open
Abstract
Using newer vaccine platforms which have been effective against malaria in rodent models, we tested five immunization regimens against Plasmodium knowlesi in rhesus monkeys. All vaccines included the same four P. knowlesi antigens: the pre-erythrocytic antigens CSP, SSP2, and erythrocytic antigens AMA1, MSP1. We used four vaccine platforms for prime or boost vaccinations: plasmids (DNA), alphavirus replicons (VRP), attenuated adenovirus serotype 5 (Ad), or attenuated poxvirus (Pox). These four platforms combined to produce five different prime/boost vaccine regimens: Pox alone, VRP/Pox, VRP/Ad, Ad/Pox, and DNA/Pox. Five rhesus monkeys were immunized with each regimen, and five Control monkeys received a mock vaccination. The time to complete vaccinations was 420 days. All monkeys were challenged twice with 100 P. knowlesi sporozoites given IV. The first challenge was given 12 days after the last vaccination, and the monkeys receiving the DNA/Pox vaccine were the best protected, with 3/5 monkeys sterilely protected and 1/5 monkeys that self-cured its parasitemia. There was no protection in monkeys that received Pox malaria vaccine alone without previous priming. The second sporozoite challenge was given 4 months after the first. All 4 monkeys that were protected in the first challenge developed malaria in the second challenge. DNA, VRP and Ad5 vaccines all primed monkeys for strong immune responses after the Pox boost. We discuss the high level but short duration of protection in this experiment and the possible benefits of the long interval between prime and boost.
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Affiliation(s)
- George Jiang
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation, Rockville, Maryland, United States of America
| | - Meng Shi
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
| | - Solomon Conteh
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
| | - Nancy Richie
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
| | - Glenna Banania
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
| | - Harini Geneshan
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
| | - Anais Valencia
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
| | - Priti Singh
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
| | - Joao Aguiar
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
| | - Keith Limbach
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
| | - Kurt I. Kamrud
- AlphaVax, Research Triangle Park, North Carolina, United States of America
| | - Jonathan Rayner
- AlphaVax, Research Triangle Park, North Carolina, United States of America
| | - Jonathan Smith
- AlphaVax, Research Triangle Park, North Carolina, United States of America
| | | | | | - Takafumi Tsuboi
- Cell-free Science and Technology Research Center, Ehime University, Matsuyama, Ehime, Japan
| | - Satoru Takeo
- Cell-free Science and Technology Research Center, Ehime University, Matsuyama, Ehime, Japan
| | - Yaeta Endo
- Cell-free Science and Technology Research Center, Ehime University, Matsuyama, Ehime, Japan
| | | | - Thomas L. Richie
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
| | - Walter R. Weiss
- Naval Medical Research Center, Malaria Program, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation, Rockville, Maryland, United States of America
- Cell-free Science and Technology Research Center, Ehime University, Matsuyama, Ehime, Japan
- * E-mail:
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Improved efficacy of a gene optimised adenovirus-based vaccine for venezuelan equine encephalitis virus. Virol J 2009; 6:118. [PMID: 19646224 PMCID: PMC2732613 DOI: 10.1186/1743-422x-6-118] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Accepted: 07/31/2009] [Indexed: 01/03/2023] Open
Abstract
Background Optimisation of genes has been shown to be beneficial for expression of proteins in a range of applications. Optimisation has increased protein expression levels through improved codon usage of the genes and an increase in levels of messenger RNA. We have applied this to an adenovirus (ad)-based vaccine encoding structural proteins (E3-E2-6K) of Venezuelan equine encephalitis virus (VEEV). Results Following administration of this vaccine to Balb/c mice, an approximately ten-fold increase in antibody response was elicited and increased protective efficacy compared to an ad-based vaccine containing non-optimised genes was observed after challenge. Conclusion This study, in which the utility of optimising genes encoding the structural proteins of VEEV is demonstrated for the first time, informs us that including optimised genes in gene-based vaccines for VEEV is essential to obtain maximum immunogenicity and protective efficacy.
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Abstract
The antiquated system used to manufacture the currently licensed inactivated influenza virus vaccines would not be adequate during an influenza virus pandemic. There is currently a search for vaccines that can be developed faster and provide superior, long-lasting immunity to influenza virus as well as other highly pathogenic viruses and bacteria. Recombinant vectors provide a safe and effective method to elicit a strong immune response to a foreign protein or epitope. This review explores the advantages and limitations of several different vectors that are currently being tested, and highlights some of the newer viruses being used as recombinant vectors.
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35
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Billeter MA, Naim HY, Udem SA. Reverse genetics of measles virus and resulting multivalent recombinant vaccines: applications of recombinant measles viruses. Curr Top Microbiol Immunol 2009; 329:129-62. [PMID: 19198565 PMCID: PMC7120638 DOI: 10.1007/978-3-540-70523-9_7] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
An overview is given on the development of technologies to allow reverse genetics of RNA viruses, i.e., the rescue of viruses from cDNA, with emphasis on nonsegmented negative-strand RNA viruses ( Mononegavirales ), as exemplified for measles virus (MV). Primarily, these technologies allowed site-directed mutagenesis, enabling important insights into a variety of aspects of the biology of these viruses. Concomitantly, foreign coding sequences were inserted to (a) allow localization of virus replication in vivo through marker gene expression, (b) develop candidate multivalent vaccines against measles and other pathogens, and (c) create candidate oncolytic viruses. The vector use of these viruses was experimentally encouraged by the pronounced genetic stability of the recombinants unexpected for RNA viruses, and by the high load of insertable genetic material, in excess of 6 kb. The known assets, such as the small genome size of the vector in comparison to DNA viruses proposed as vectors, the extensive clinical experience of attenuated MV as vaccine with a proven record of high safety and efficacy, and the low production cost per vaccination dose are thus favorably complemented.
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Affiliation(s)
- M A Billeter
- University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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36
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A baculovirus dual expression system-based malaria vaccine induces strong protection against Plasmodium berghei sporozoite challenge in mice. Infect Immun 2009; 77:1782-9. [PMID: 19223476 DOI: 10.1128/iai.01226-08] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously shown that a recombinant baculovirus that displays Plasmodium berghei circumsporozoite protein (PbCSP), a homolog of the leading human malaria vaccine candidate, on the viral envelope protected 60% of mice against P. berghei infection. Here, we describe a second-generation baculovirus vaccine based on the "baculovirus dual expression system," which drives PbCSP expression by a dual promoter that consists of tandemly arranged baculovirus-derived polyhedrin and mammal-derived cytomegalovirus promoters. The baculovirus-based PbCSP vaccine not only displayed PbCSP on the viral envelope but also expressed PbCSP upon transduction of mammalian cells. Immunization with the baculovirus-based PbCSP vaccine elicited high PbCSP-specific antibody titers (predominantly immunoglobulin G1 [IgG1] and IgG2a) and PbCSP-specific CD8(+) T-cell responses without extraneous immunological adjuvants in mice, indicating that there was induction of both Th1 and Th2 responses (a mixed Th1/Th2 response). Importantly, upon intramuscular inoculation, the baculovirus-based PbCSP vaccine conferred complete protection against sporozoite challenge. Thus, the baculovirus-based PbCSP vaccine induced strong protective immune responses against preerythrocytic parasites. These results introduce a novel concept for the baculovirus dual expression system that functions as both a subunit vaccine and a DNA vaccine and offer a promising new alternative to current human vaccine delivery platforms.
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Cavanagh DR, Remarque EJ, Sauerwein RW, Hermsen CC, Luty AJ. Influenza virosomes: a flu jab for malaria? Trends Parasitol 2008; 24:382-5. [DOI: 10.1016/j.pt.2008.06.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 06/05/2008] [Accepted: 06/13/2008] [Indexed: 01/06/2023]
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Affiliation(s)
- Alex John London
- Center for the Advancement of Applied Ethics and Political Philosophy, Department of Philosophy, Carnegie Mellon, University Pittsburgh, PA, USA
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39
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Peek LJ, Middaugh CR, Berkland C. Nanotechnology in vaccine delivery. Adv Drug Deliv Rev 2008; 60:915-28. [PMID: 18325628 PMCID: PMC7103321 DOI: 10.1016/j.addr.2007.05.017] [Citation(s) in RCA: 361] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Accepted: 05/01/2007] [Indexed: 01/19/2023]
Abstract
With very few adjuvants currently being used in marketed human vaccines, a critical need exists for novel immunopotentiators and delivery vehicles capable of eliciting humoral, cellular and mucosal immunity. Such crucial vaccine components could facilitate the development of novel vaccines for viral and parasitic infections, such as hepatitis, HIV, malaria, cancer, etc. In this review, we discuss clinical trial results for various vaccine adjuvants and delivery vehicles being developed that are approximately nanoscale (< 1000 nm) in size. Humoral immune responses have been observed for most adjuvants and delivery platforms while only viral vectors, ISCOMs and Montanide™ ISA 51 and 720 have shown cytotoxic T cell responses in the clinic. MF59 and MPL® have elicited Th1 responses, and virus-like particles, non-degradable nanoparticles and liposomes have also generated cellular immunity. Such vaccine components have also been evaluated for alternative routes of administration with clinical successes reported for intranasal delivery of viral vectors and proteosomes and oral delivery of a VLP vaccine.
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40
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Schoenly KA, Weiner DB. Human immunodeficiency virus type 1 vaccine development: recent advances in the cytotoxic T-lymphocyte platform "spotty business". J Virol 2008; 82:3166-80. [PMID: 17989174 PMCID: PMC2268479 DOI: 10.1128/jvi.01634-07] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Kimberly A Schoenly
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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Abstract
The development and implementation of a malaria vaccine would constitute a major breakthrough for global health. Recently, numerous new candidates have entered clinical testing, following strategies that are as diverse as the malaria cycle is complex. While promising results have been obtained, some candidate vaccines have not fulfilled expectations. The challenges are not merely scientific; further progresses will require the development of competent investigator networks, partnerships between academics, industry and funding agencies, and continuous political commitment. In this review, we present the developmental status of all malaria vaccine candidates that are currently in human clinical testing against Plasmodium falciparum, as well as selected malaria vaccine candidates at preclinical development stage, and discuss the main challenges facing the field of malaria vaccine development.
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Affiliation(s)
- Johan Vekemans
- GlaxoSmithKline Biologicals, Emerging Diseases, Global Clinical Research and Development Vaccines, Rixensart, Belgium.
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42
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Heterologous boosting of recombinant adenoviral prime immunization with a novel vesicular stomatitis virus-vectored tuberculosis vaccine. Mol Ther 2008; 16:1161-9. [PMID: 18388911 PMCID: PMC7185538 DOI: 10.1038/mt.2008.59] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Pulmonary tuberculosis (TB) remains a serious health problem worldwide. Effective vaccination strategies are needed. We report the development of a novel TB vaccine using vesicular stomatitis virus (VSV) as a viral vector system to express Ag85A. VSVAg85A was shown to be immunogenic when given to mice by either an intranasal or an intramuscular (i.m.) route. Although distinct T-cell profiles resulted from both routes of immunization, only intranasal delivery generated a mucosal T-cell response that was protective upon pulmonary Mycobacterium tuberculosis (M.tb) challenge. While this protection manifested at an early time-point after immunization, it was not sustained. The potential of VSVAg85A to be used as a mucosal booster for parenteral priming by an adenoviral TB vaccine expressing Ag85A (AdAg85A) was investigated. VSVAg85A immunization markedly boosted antigen-specific T-cell responses in the airway lumen while also augmenting immune activation in the systemic compartment, after AdAg85A priming. This translated into significantly better protective efficacy against pulmonary challenge with M.tb than either vaccine used alone. Our study therefore suggests that VSV as a vector system is a promising candidate to be used in a heterologous viral prime-boost immunization regimen against intracellular bacterial infection.
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Hafalla JCR, Rai U, Bernal-Rubio D, Rodriguez A, Zavala F. Efficient development of plasmodium liver stage-specific memory CD8+ T cells during the course of blood-stage malarial infection. J Infect Dis 2008; 196:1827-35. [PMID: 18190264 DOI: 10.1086/522965] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Immunity to Plasmodium liver stages in individuals in malaria-endemic areas is inextricably linked to concomitant blood-stage parasitemia. Although Plasmodium sporozoite infection induces measurable CD8+ T cell responses, the development of memory T cells during active erythrocytic infection remains uncharacterized. Using transgenic T cells, we assessed antigen-specific effector CD8+ T cell responses induced by normal (NorSpz) and radiation-attenuated (IrrSpz) Plasmodium yoelii sporozoites. The magnitude, phenotypic activation, and differentiation pathway of CD8+ T cells were similarly induced by NorSpz and IrrSpz. Moreover, in normal mice, memory T cells elicited after priming with NorSpz and IrrSpz generated identical recall responses after a heterologous boost strategy. Furthermore, these recall responses exhibited comparable in vivo antiparasite activity. Our results indicate that sporozoites that retain their infective capacity induce memory CD8+ T cells that are robustly recalled by secondary immunization. Thus, erythrocytic infection does not preclude the establishment of memory CD8+ T cell responses to malarial liver stages.
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Affiliation(s)
- Julius C R Hafalla
- Department of Medical Parasitology, New York University School of Medicine, 341 E. 25th Street, New York, NY 10010, USA
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Remarque EJ, Faber BW, Kocken CHM, Thomas AW. Apical membrane antigen 1: a malaria vaccine candidate in review. Trends Parasitol 2008; 24:74-84. [PMID: 18226584 DOI: 10.1016/j.pt.2007.12.002] [Citation(s) in RCA: 217] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 10/31/2007] [Accepted: 12/20/2007] [Indexed: 10/22/2022]
Abstract
Apical membrane antigen 1 (AMA1) is a micronemal protein of apicomplexan parasites that appears to be essential during the invasion of host cells. Immune responses to Plasmodium AMA1 can have profound parasite-inhibitory effects, both as measured in vitro and in animal challenge models, suggesting AMA1 as a potential vaccine component. However, AMA1 is polymorphic, probably as a result of immune selection operating on an important target of naturally occurring immunity. The current understanding of AMA1 will be presented, particularly in relation to the vaccine potential of AMA1 and the approaches being taken towards clinical development.
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Affiliation(s)
- Edmond J Remarque
- Department of Parasitology, Biomedical Primate Research Centre, 2280 GH Rijswijk, The Netherlands
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45
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Yang TC, Millar JB, Grinshtein N, Bassett J, Finn J, Bramson JL. T-cell immunity generated by recombinant adenovirus vaccines. Expert Rev Vaccines 2007; 6:347-56. [PMID: 17542750 DOI: 10.1586/14760584.6.3.347] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Recombinant adenovirus vaccines show great promise for generating protective immunity against infectious agents and tumors. Our studies have identified several interesting biological features of the adenovirus vector that influence the T-cell response. Notably, we have demonstrated that following immunization with adenovirus vaccines, the transgene antigen remains available to the system for a longer period than would be expected, resulting in a T-cell population with a sustained effector phenotype. The implications of these observations with regards to the utility of adenovirus vaccines are discussed.
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Affiliation(s)
- Teng Chih Yang
- Center for Gene Therapeutics, Department of Pathology and Molecular Medicine, McMaster University, 1200 Main Street West, Hamilton, Ontario, L8N 3Z5, Canada.
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Saul A, Fay MP. Human immunity and the design of multi-component, single target vaccines. PLoS One 2007; 2:e850. [PMID: 17786221 PMCID: PMC1952173 DOI: 10.1371/journal.pone.0000850] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Accepted: 08/14/2007] [Indexed: 12/17/2022] Open
Abstract
Background Inclusion of multiple immunogens to target a single organism is a strategy being pursued for many experimental vaccines, especially where it is difficult to generate a strongly protective response from a single immunogen. Although there are many human vaccines that contain multiple defined immunogens, in almost every case each component targets a different pathogen. As a consequence, there is little practical experience for deciding where the increased complexity of vaccines with multiple defined immunogens vaccines targeting single pathogens will be justifiable. Methodology/Principal Findings A mathematical model, with immunogenicity parameters derived from a database of human responses to established vaccines, was used to predict the increase in the efficacy and the proportion of the population protected resulting from addition of further immunogens. The gains depended on the relative protection and the range of responses in the population to each immunogen and also to the correlation of the responses between immunogens. In most scenarios modeled, the gain in overall efficacy obtained by adding more immunogens was comparable to gains obtained from a single immunogen through the use of better formulations or adjuvants. Multi-component single target vaccines were more effective at decreasing the proportion of poor responders than increasing the overall efficacy of the vaccine in a population. Conclusions/Significance Inclusion of limited number of antigens in a vaccine aimed at targeting a single organism will increase efficacy, but the gains are relatively modest and for a practical vaccine there are constraints that are likely to limit multi-component single target vaccines to a small number of key antigens. The model predicts that this type of vaccine will be most useful where the critical issue is the reduction in proportion of poor responders.
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Affiliation(s)
- Allan Saul
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
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Druilhe P, Barnwell JW. Pre-erythrocytic stage malaria vaccines: time for a change in path. Curr Opin Microbiol 2007; 10:371-8. [PMID: 17709281 DOI: 10.1016/j.mib.2007.07.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Accepted: 07/25/2007] [Indexed: 11/17/2022]
Abstract
Vaccines against the pre-erythrocytic stages of malaria hold the greatest promise as an effective intervention tool against malaria, as shown by immunization with radiation-attenuated sporozoites over four decades ago. To date, however, the development of subunit vaccines, while generating high expectations and investment, has not lived up at all to the promise. This path has been characterized by insufficient research into both identification of key defense mechanisms in humans and the discovery of better antigens, focusing rather on a technological race of how to present mainly a single antigen. The lack of success has also led, perhaps from desperation, to a revival of the live attenuated sporozoite approach, handicapped, however, by major bottlenecks in production, safety, and regulatory issues. It should now be clear that the field can no longer continue to succeed in mice and fail in the clinic. We advocate here in favor of a third option, relying on an understanding of the basis of attenuated sporozoite immunity in humans, to provide leads to the discovery of critical immunogens and the use of models with validated relevance to the human situation in order to rationalize and renew the promise of pre-erythrocytic subunit vaccines.
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Affiliation(s)
- Pierre Druilhe
- Biomedical Parasitology Unit, Department of Parasitology & Mycology, Pasteur Institute, Paris, France.
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Heppner DG, Schwenk RJ, Arnot D, Sauerwein RW, Luty AJF. The dog that did not bark: malaria vaccines without antibodies. Trends Parasitol 2007; 23:293-6. [PMID: 17512252 DOI: 10.1016/j.pt.2007.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Revised: 03/20/2007] [Accepted: 05/03/2007] [Indexed: 01/29/2023]
Abstract
To date, the only pre-blood stage vaccine to confer protection against malaria in field trials elicits both antigen-specific antibody and T-cell responses. Recent clinical trials of new heterologous prime-boost malaria vaccine regimens using DNA, fowlpox or MVA, have chiefly elicited T-cell responses that have promisingly reduced hepatic merozoites in challenge trials, but failed to protect in field trials. These encouraging results suggest further augmentation of T-cell responses to pre-blood stage antigens might one day contribute to a highly protective vaccine. We envision that a highly protective pre-erythrocytic vaccine will likely be based upon a heterologous prime-boost regimen that induces both appropriate T-cell responses as well as robust and protracted antibody production.
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Affiliation(s)
- D Gray Heppner
- Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
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Abstract
The exceptional discoveries of antigen/gene delivery systems have allowed the development of novel prophylactic and therapeutic vaccine candidates. This review highlights various antigen-delivery systems, particularly viral vectors, and assesses the underlying technologies in light of their use against AIDS and malaria. Although such recombinant vectors may face extensive preclinical testing and will possibly have to meet stringent regulatory requirements, some of these vectors may benefit from the profound industrial and clinical experience of the parent vaccine. Most notably, novel vaccines based on live, recombinant vectors may combine the induction of broad, strong and persistent immune responses with acceptable safety profiles.
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