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Sheehy SH, Spencer AJ, Douglas AD, Sim BKL, Longley RJ, Edwards NJ, Poulton ID, Kimani D, Williams AR, Anagnostou NA, Roberts R, Kerridge S, Voysey M, James ER, Billingsley PF, Gunasekera A, Lawrie AM, Hoffman SL, Hill AVS. Optimising Controlled Human Malaria Infection Studies Using Cryopreserved P. falciparum Parasites Administered by Needle and Syringe. PLoS One 2013; 8:e65960. [PMID: 23823332 PMCID: PMC3688861 DOI: 10.1371/journal.pone.0065960] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 04/29/2013] [Indexed: 11/18/2022] Open
Abstract
Background Controlled human malaria infection (CHMI) studies have become a routine tool to evaluate efficacy of candidate anti-malarial drugs and vaccines. To date, CHMI trials have mostly been conducted using the bite of infected mosquitoes, restricting the number of trial sites that can perform CHMI studies. Aseptic, cryopreserved P. falciparum sporozoites (PfSPZ Challenge) provide a potentially more accurate, reproducible and practical alternative, allowing a known number of sporozoites to be administered simply by injection. Methodology We sought to assess the infectivity of PfSPZ Challenge administered in different dosing regimens to malaria-naive healthy adults (n = 18). Six participants received 2,500 sporozoites intradermally (ID), six received 2,500 sporozoites intramuscularly (IM) and six received 25,000 sporozoites IM. Findings Five out of six participants receiving 2,500 sporozoites ID, 3/6 participants receiving 2,500 sporozoites IM and 6/6 participants receiving 25,000 sporozoites IM were successfully infected. The median time to diagnosis was 13.2, 17.8 and 12.7 days for 2,500 sporozoites ID, 2,500 sporozoites IM and 25,000 sporozoites IM respectively (Kaplan Meier method; p = 0.024 log rank test). Conclusions 2,500 sporozoites ID and 25,000 sporozoites IM have similar infectivities. Given the dose response in infectivity seen with IM administration, further work should evaluate increasing doses of PfSPZ Challenge IM to identify a dosing regimen that reliably infects 100% of participants. Trial Registration ClinicalTrials.gov NCT01465048
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Affiliation(s)
- Susanne H. Sheehy
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | | | | | - B. Kim Lee Sim
- Sanaria Inc., Rockville, Maryland, United States of America
| | - Rhea J. Longley
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
| | - Nick J. Edwards
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
| | - Ian D. Poulton
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | - Domtila Kimani
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute, Kilifi, Kenya
| | - Andrew R. Williams
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
| | - Nicholas A. Anagnostou
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | - Rachel Roberts
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | - Simon Kerridge
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | - Merryn Voysey
- Centre for Statistics in Medicine, University of Oxford, Oxford, United Kingdom
| | - Eric R. James
- Sanaria Inc., Rockville, Maryland, United States of America
| | | | | | - Alison M. Lawrie
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | | | - Adrian V. S. Hill
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
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Sheehy SH, Douglas AD, Draper SJ. Challenges of assessing the clinical efficacy of asexual blood-stage Plasmodium falciparum malaria vaccines. Hum Vaccin Immunother 2013; 9:1831-40. [PMID: 23778312 PMCID: PMC3906345 DOI: 10.4161/hv.25383] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In the absence of any highly effective vaccine candidate against Plasmodium falciparum malaria, it remains imperative for the field to pursue all avenues that may lead to the successful development of such a formulation. The development of a subunit vaccine targeting the asexual blood-stage of Plasmodium falciparum malaria infection has proven particularly challenging with only limited success to date in clinical trials. However, only a fraction of potential blood-stage vaccine antigens have been evaluated as targets, and a number of new promising candidate antigen formulations and delivery platforms are approaching clinical development. It is therefore essential that reliable and sensitive methods of detecting, or ruling out, even modest efficacy of blood-stage vaccines in small clinical trials be established. In this article we evaluate the challenges facing blood-stage vaccine developers, assess the appropriateness and limitations of various in vivo approaches for efficacy assessment and suggest future directions for the field.
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Douglas AD, Edwards NJ, Duncan CJA, Thompson FM, Sheehy SH, O'Hara GA, Anagnostou N, Walther M, Webster DP, Dunachie SJ, Porter DW, Andrews L, Gilbert SC, Draper SJ, Hill AVS, Bejon P. Comparison of modeling methods to determine liver-to-blood inocula and parasite multiplication rates during controlled human malaria infection. J Infect Dis 2013; 208:340-5. [PMID: 23570846 PMCID: PMC3685228 DOI: 10.1093/infdis/jit156] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Controlled human malaria infection is used to measure efficacy of candidate malaria vaccines before field studies are undertaken. Mathematical modeling using data from quantitative polymerase chain reaction (qPCR) parasitemia monitoring can discriminate between vaccine effects on the parasite's liver and blood stages. Uncertainty regarding the most appropriate modeling method hinders interpretation of such trials. We used qPCR data from 267 Plasmodium falciparum infections to compare linear, sine-wave, and normal-cumulative-density-function models. We find that the parameters estimated by these models are closely correlated, and their predictive accuracy for omitted data points was similar. We propose that future studies include the linear model.
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Ogwang C, Afolabi M, Kimani D, Jagne YJ, Sheehy SH, Bliss CM, Duncan CJA, Collins KA, Garcia Knight MA, Kimani E, Anagnostou NA, Berrie E, Moyle S, Gilbert SC, Spencer AJ, Soipei P, Mueller J, Okebe J, Colloca S, Cortese R, Viebig NK, Roberts R, Gantlett K, Lawrie AM, Nicosia A, Imoukhuede EB, Bejon P, Urban BC, Flanagan KL, Ewer KJ, Chilengi R, Hill AVS, Bojang K. Safety and immunogenicity of heterologous prime-boost immunisation with Plasmodium falciparum malaria candidate vaccines, ChAd63 ME-TRAP and MVA ME-TRAP, in healthy Gambian and Kenyan adults. PLoS One 2013; 8:e57726. [PMID: 23526949 PMCID: PMC3602521 DOI: 10.1371/journal.pone.0057726] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 01/24/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Heterologous prime boost immunization with chimpanzee adenovirus 63 (ChAd63) and Modified vaccinia Virus Ankara (MVA) vectored vaccines is a strategy recently shown to be capable of inducing strong cell mediated responses against several antigens from the malaria parasite. ChAd63-MVA expressing the Plasmodium falciparum pre-erythrocytic antigen ME-TRAP (multiple epitope string with thrombospondin-related adhesion protein) is a leading malaria vaccine candidate, capable of inducing sterile protection in malaria naïve adults following controlled human malaria infection (CHMI). METHODOLOGY We conducted two Phase Ib dose escalation clinical trials assessing the safety and immunogenicity of ChAd63-MVA ME-TRAP in 46 healthy malaria exposed adults in two African countries with similar malaria transmission patterns. RESULTS ChAd63-MVA ME-TRAP was shown to be safe and immunogenic, inducing high-level T cell responses (median >1300 SFU/million PBMC). CONCLUSIONS ChAd63-MVA ME-TRAP is a safe and highly immunogenic vaccine regimen in adults with prior exposure to malaria. Further clinical trials to assess safety and immunogenicity in children and infants and protective efficacy in the field are now warranted. TRIAL REGISTRATION Pactr.org PACTR2010020001771828 Pactr.org PACTR201008000221638 ClinicalTrials.gov NCT01373879 NCT01373879 ClinicalTrials.gov NCT01379430 NCT01379430.
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Affiliation(s)
- Caroline Ogwang
- Kenya Medical Research Institute, Centre for Geographical Medical Research (Coast), Kilifi, Kenya
| | | | - Domtila Kimani
- Kenya Medical Research Institute, Centre for Geographical Medical Research (Coast), Kilifi, Kenya
| | | | - Susanne H. Sheehy
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, Churchill Hospital, Oxford, United Kingdom
- * E-mail:
| | - Carly M. Bliss
- The Jenner Institute Laboratories, University of Oxford, Old Road Campus Research Building, Oxford, United Kingdom
| | - Christopher J. A. Duncan
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, Churchill Hospital, Oxford, United Kingdom
| | - Katharine A. Collins
- The Jenner Institute Laboratories, University of Oxford, Old Road Campus Research Building, Oxford, United Kingdom
| | - Miguel A. Garcia Knight
- Kenya Medical Research Institute, Centre for Geographical Medical Research (Coast), Kilifi, Kenya
| | - Eva Kimani
- Kenya Medical Research Institute, Centre for Geographical Medical Research (Coast), Kilifi, Kenya
| | - Nicholas A. Anagnostou
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, Churchill Hospital, Oxford, United Kingdom
| | - Eleanor Berrie
- Clinical Biomanufacturing Facility, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Sarah Moyle
- Clinical Biomanufacturing Facility, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Sarah C. Gilbert
- The Jenner Institute Laboratories, University of Oxford, Old Road Campus Research Building, Oxford, United Kingdom
| | - Alexandra J. Spencer
- The Jenner Institute Laboratories, University of Oxford, Old Road Campus Research Building, Oxford, United Kingdom
| | - Peninah Soipei
- Kenya Medical Research Institute, Centre for Geographical Medical Research (Coast), Kilifi, Kenya
| | | | - Joseph Okebe
- Medical Research Council Unit, Fajara, The Gambia
| | | | | | | | - Rachel Roberts
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, Churchill Hospital, Oxford, United Kingdom
| | - Katherine Gantlett
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, Churchill Hospital, Oxford, United Kingdom
| | - Alison M. Lawrie
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, Churchill Hospital, Oxford, United Kingdom
| | - Alfredo Nicosia
- Okairòs AG, Rome, Italy
- CEINGE, Naples, Italy
- Department of Molecular Medicine and Medical Biotechnology, University Federico II Naples, Naples, Italy
| | | | - Philip Bejon
- Kenya Medical Research Institute, Centre for Geographical Medical Research (Coast), Kilifi, Kenya
| | - Britta C. Urban
- Kenya Medical Research Institute, Centre for Geographical Medical Research (Coast), Kilifi, Kenya
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | | | - Katie J. Ewer
- The Jenner Institute Laboratories, University of Oxford, Old Road Campus Research Building, Oxford, United Kingdom
| | - Roma Chilengi
- Kenya Medical Research Institute, Centre for Geographical Medical Research (Coast), Kilifi, Kenya
| | - Adrian V. S. Hill
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, Churchill Hospital, Oxford, United Kingdom
- The Jenner Institute Laboratories, University of Oxford, Old Road Campus Research Building, Oxford, United Kingdom
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Elias SC, Collins KA, Halstead FD, Choudhary P, Bliss CM, Ewer KJ, Sheehy SH, Duncan CJA, Biswas S, Hill AVS, Draper SJ. Assessment of immune interference, antagonism, and diversion following human immunization with biallelic blood-stage malaria viral-vectored vaccines and controlled malaria infection. J Immunol 2013; 190:1135-47. [PMID: 23293353 PMCID: PMC3672846 DOI: 10.4049/jimmunol.1201455] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Overcoming antigenic variation is one of the major challenges in the development of an effective vaccine against Plasmodium falciparum, a causative agent of human malaria. Inclusion of multiple Ag variants in subunit vaccine candidates is one strategy that has aimed to overcome this problem for the leading blood-stage malaria vaccine targets, that is, merozoite surface protein 1 (MSP1) and apical membrane Ag 1 (AMA1). However, previous studies, utilizing malaria Ags, have concluded that inclusion of multiple allelic variants, encoding altered peptide ligands, in such a vaccine may be detrimental to both the priming and in vivo restimulation of Ag-experienced T cells. In this study, we analyze the T cell responses to two alleles of MSP1 and AMA1 induced by vaccination of malaria-naive adult volunteers with bivalent viral-vectored vaccine candidates. We show a significant bias to the 3D7/MAD20 allele compared with the Wellcome allele for the 33 kDa region of MSP1, but not for the 19 kDa fragment or the AMA1 Ag. Although this bias could be caused by "immune interference" at priming, the data do not support a significant role for "immune antagonism" during memory T cell restimulation, despite observation of the latter at a minimal epitope level in vitro. A lack of class I HLA epitopes in the Wellcome allele that are recognized by vaccinated volunteers may in fact contribute to the observed bias. We also show that controlled infection with 3D7 strain P. falciparum parasites neither boosts existing 3D7-specific T cell responses nor appears to "immune divert" cellular responses toward the Wellcome allele.
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Affiliation(s)
- Sean C Elias
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, United Kingdom.
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Duncan CJA, Rowland R, Lillie PJ, Meyer J, Sheehy SH, O'Hara GA, Hamill M, Donaldson H, Dinsmore L, Poulton ID, Gilbert SC, McShane H, Hill AVS. Incidental diagnosis in healthy clinical trial subjects. Clin Transl Sci 2012; 5:348-50. [PMID: 22883613 PMCID: PMC3465775 DOI: 10.1111/j.1752-8062.2011.00393.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Previously unrecognized medical conditions identified in volunteers for early phase clinical studies have significant clinical and ethical implications for the participant. It is therefore crucial that the potential for unexpected diagnosis is addressed during the informed consent process. But the frequency of incidental diagnosis in healthy volunteers who attend for clinical trial screening remains unclear. To assess this we retrospectively analyzed 1,131 independent screening visits for 990 volunteers at a single academic center over a 10‐year period to describe the frequency and nature of new clinical findings. Overall 23 of 990 volunteers (2.3%) were excluded at screening for a newly diagnosed medical abnormality. Some clinically important conditions, such as nephrotic syndrome and familial hypercholesterolemia were identified. The frequency of abnormalities was associated with increasing age in males (p= 0.02 χ2 for trend) but not females (p= 0.82). These data will assist those planning and conducting phase I/II vaccine trials in healthy volunteers, and importantly should strengthen the informed consent of future trial participants. Clin Trans Sci 2012; Volume 5: 348–350
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Affiliation(s)
- Christopher J A Duncan
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Churchill Drive, OX3 7LJ, United Kingdom.
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7
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Lillie PJ, Duncan CJA, Sheehy SH, Meyer J, O'Hara GA, Gilbert SC, Hill AVS. Distinguishing malaria and influenza: early clinical features in controlled human experimental infection studies. Travel Med Infect Dis 2012; 10:192-6. [PMID: 22531678 PMCID: PMC3778896 DOI: 10.1016/j.tmaid.2012.03.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 03/21/2012] [Accepted: 03/26/2012] [Indexed: 11/18/2022]
Abstract
During the H1N1 influenza pandemic (pH1N1/09) diagnostic algorithms were developed to guide antiviral provision. However febrile illnesses are notoriously difficult to distinguish clinically. Recent evidence highlights the importance of incorporating travel history into diagnostic algorithms to prevent the catastrophic misdiagnosis of life-threatening infections such as malaria. We applied retrospectively the UK pH1N1/09 case definition to a unique cohort of healthy adult volunteers exposed to Plasmodium falciparum malaria or influenza to assess the predictive value of this case definition, and to explore the distinguishing clinical features of early phase infection with these pathogens under experimental conditions. For influenza exposure the positive predictive value of the pH1N1/09 case definition was only 0.38 (95% CI: 0.06–0.60), with a negative predictive value of 0.27 (95% CI: 0.02–0.51). Interestingly, 8/11 symptomatic malaria-infected adults would have been inappropriately classified with influenza by the pH1N1/09 case definition, while 5/8 symptomatic influenza-exposed volunteers would have been classified without influenza (P = 0.18 Fisher's exact). Cough (P = 0.005) and nasal symptoms (P = 0.001) were the only clinical features that distinguished influenza-exposed from malaria-exposed volunteers. An open mind regarding the clinical cause of undifferentiated febrile illness, particularly in the absence of upper respiratory tract symptoms, remains important even during influenza pandemic settings. These data support incorporating travel history into pandemic algorithms.
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Affiliation(s)
- Patrick J Lillie
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, UK.
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Lillie PJ, Berthoud TK, Powell TJ, Lambe T, Mullarkey C, Spencer AJ, Hamill M, Peng Y, Blais ME, Duncan CJA, Sheehy SH, Havelock T, Faust SN, Williams RL, Gilbert A, Oxford J, Dong T, Hill AVS, Gilbert SC. Preliminary assessment of the efficacy of a T-cell-based influenza vaccine, MVA-NP+M1, in humans. Clin Infect Dis 2012; 55:19-25. [PMID: 22441650 PMCID: PMC3369564 DOI: 10.1093/cid/cis327] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A single vaccination with MVA-NP+M1 boosts T-cell responses to conserved influenza
antigens in humans. Protection against influenza disease and virus shedding was
demonstrated in an influenza virus challenge study. Background. The novel influenza vaccine MVA-NP+M1
is designed to boost cross-reactive T-cell responses to internal antigens of the influenza
A virus that are conserved across all subtypes, providing protection against both
influenza disease and virus shedding against all influenza A viruses. Following a phase 1
clinical study that demonstrated vaccine safety and immunogenicity, a phase 2a vaccination
and influenza challenge study has been conducted in healthy adult volunteers. Methods. Volunteers with no measurable serum
antibodies to influenza A/Wisconsin/67/2005 received either a single vaccination with
MVA-NP+M1 or no vaccination. T-cell responses to the vaccine antigens were measured
at enrollment and again prior to virus challenge. All volunteers underwent intranasal
administration of influenza A/Wisconsin/67/2005 while in a quarantine unit and were
monitored for symptoms of influenza disease and virus shedding. Results. Volunteers had a significantly increased
T-cell response to the vaccine antigens following a single dose of the vaccine, with an
increase in cytolytic effector molecules. Intranasal influenza challenge was undertaken
without safety issues. Two of 11 vaccinees and 5 of 11 control subjects developed
laboratory-confirmed influenza (symptoms plus virus shedding). Symptoms of influenza were
less pronounced in the vaccinees and there was a significant reduction in the number of
days of virus shedding in those vaccinees who developed influenza (mean, 1.09 days in
controls, 0.45 days in vaccinees, P = .036). Conclusions. This study provides the first
demonstration of clinical efficacy of a T-cell–based influenza vaccine and indicates
that further clinical development should be undertaken. Clinical Trials Registration. NCT00993083.
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O'Hara GA, Duncan CJA, Ewer KJ, Collins KA, Elias SC, Halstead FD, Goodman AL, Edwards NJ, Reyes-Sandoval A, Bird P, Rowland R, Sheehy SH, Poulton ID, Hutchings C, Todryk S, Andrews L, Folgori A, Berrie E, Moyle S, Nicosia A, Colloca S, Cortese R, Siani L, Lawrie AM, Gilbert SC, Hill AVS. Clinical assessment of a recombinant simian adenovirus ChAd63: a potent new vaccine vector. J Infect Dis 2012; 205:772-81. [PMID: 22275401 PMCID: PMC3274376 DOI: 10.1093/infdis/jir850] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2011] [Accepted: 10/05/2011] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Vaccine development in human Plasmodium falciparum malaria has been hampered by the exceptionally high levels of CD8(+) T cells required for efficacy. Use of potently immunogenic human adenoviruses as vaccine vectors could overcome this problem, but these are limited by preexisting immunity to human adenoviruses. METHODS From 2007 to 2010, we undertook a phase I dose and route finding study of a new malaria vaccine, a replication-incompetent chimpanzee adenovirus 63 (ChAd63) encoding the preerythrocytic insert multiple epitope thrombospondin-related adhesion protein (ME-TRAP; n = 54 vaccinees) administered alone (n = 28) or with a modified vaccinia virus Ankara (MVA) ME-TRAP booster immunization 8 weeks later (n = 26). We observed an excellent safety profile. High levels of TRAP antigen-specific CD8(+) and CD4(+) T cells, as detected by interferon γ enzyme-linked immunospot assay and flow cytometry, were induced by intramuscular ChAd63 ME-TRAP immunization at doses of 5 × 10(10) viral particles and above. Subsequent administration of MVA ME-TRAP boosted responses to exceptionally high levels, and responses were maintained for up to 30 months postvaccination. CONCLUSIONS The ChAd63 chimpanzee adenovirus vector appears safe and highly immunogenic, providing a viable alternative to human adenoviruses as vaccine vectors for human use. CLINICAL TRIALS REGISTRATION NCT00890019.
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Affiliation(s)
- Geraldine A O'Hara
- Centre for Clinical Vaccinology and Tropical Medicine and the Jenner Institute Laboratories, University of Oxford, UK.
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Sheehy SH, Duncan CJA, Elias SC, Biswas S, Collins KA, O'Hara GA, Halstead FD, Ewer KJ, Mahungu T, Spencer AJ, Miura K, Poulton ID, Dicks MDJ, Edwards NJ, Berrie E, Moyle S, Colloca S, Cortese R, Gantlett K, Long CA, Lawrie AM, Gilbert SC, Doherty T, Nicosia A, Hill AVS, Draper SJ. Phase Ia clinical evaluation of the safety and immunogenicity of the Plasmodium falciparum blood-stage antigen AMA1 in ChAd63 and MVA vaccine vectors. PLoS One 2012; 7:e31208. [PMID: 22363582 PMCID: PMC3283618 DOI: 10.1371/journal.pone.0031208] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 01/04/2012] [Indexed: 02/07/2023] Open
Abstract
Background Traditionally, vaccine development against the blood-stage of Plasmodium falciparum infection has focused on recombinant protein-adjuvant formulations in order to induce high-titer growth-inhibitory antibody responses. However, to date no such vaccine encoding a blood-stage antigen(s) alone has induced significant protective efficacy against erythrocytic-stage infection in a pre-specified primary endpoint of a Phase IIa/b clinical trial designed to assess vaccine efficacy. Cell-mediated responses, acting in conjunction with functional antibodies, may be necessary for immunity against blood-stage P. falciparum. The development of a vaccine that could induce both cell-mediated and humoral immune responses would enable important proof-of-concept efficacy studies to be undertaken to address this question. Methodology We conducted a Phase Ia, non-randomized clinical trial in 16 healthy, malaria-naïve adults of the chimpanzee adenovirus 63 (ChAd63) and modified vaccinia virus Ankara (MVA) replication-deficient viral vectored vaccines encoding two alleles (3D7 and FVO) of the P. falciparum blood-stage malaria antigen; apical membrane antigen 1 (AMA1). ChAd63-MVA AMA1 administered in a heterologous prime-boost regime was shown to be safe and immunogenic, inducing high-level T cell responses to both alleles 3D7 (median 2036 SFU/million PBMC) and FVO (median 1539 SFU/million PBMC), with a mixed CD4+/CD8+ phenotype, as well as substantial AMA1-specific serum IgG responses (medians of 49 µg/mL and 41 µg/mL for 3D7 and FVO AMA1 respectively) that demonstrated growth inhibitory activity in vitro. Conclusions ChAd63-MVA is a safe and highly immunogenic delivery platform for both alleles of the AMA1 antigen in humans which warrants further efficacy testing. ChAd63-MVA is a promising heterologous prime-boost vaccine strategy that could be applied to numerous other diseases where strong cellular and humoral immune responses are required for protection. Trial Registration ClinicalTrials.gov NCT01095055
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Affiliation(s)
- Susanne H Sheehy
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, United Kingdom.
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Sheehy SH, Duncan CJA, Elias SC, Collins KA, Ewer KJ, Spencer AJ, Williams AR, Halstead FD, Moretz SE, Miura K, Epp C, Dicks MDJ, Poulton ID, Lawrie AM, Berrie E, Moyle S, Long CA, Colloca S, Cortese R, Gilbert SC, Nicosia A, Hill AVS, Draper SJ. Phase Ia clinical evaluation of the Plasmodium falciparum blood-stage antigen MSP1 in ChAd63 and MVA vaccine vectors. Mol Ther 2011; 19:2269-76. [PMID: 21862998 DOI: 10.1038/mt.2011.176] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Efficacy trials of antibody-inducing protein-in-adjuvant vaccines targeting the blood-stage Plasmodium falciparum malaria parasite have so far shown disappointing results. The induction of cell-mediated responses in conjunction with antibody responses is thought to be one alternative strategy that could achieve protective efficacy in humans. Here, we prepared chimpanzee adenovirus 63 (ChAd63) and modified vaccinia virus Ankara (MVA) replication-deficient vectors encoding the well-studied P. falciparum blood-stage malaria antigen merozoite surface protein 1 (MSP1). A phase Ia clinical trial was conducted in healthy adults of a ChAd63-MVA MSP1 heterologous prime-boost immunization regime. The vaccine was safe and generally well tolerated. Fewer systemic adverse events (AEs) were observed following ChAd63 MSP1 than MVA MSP1 administration. Exceptionally strong T-cell responses were induced, and these displayed a mixed of CD4(+) and CD8(+) phenotype. Substantial MSP1-specific serum immunoglobulin G (IgG) antibody responses were also induced, which were capable of recognizing native parasite antigen, but these did not reach titers sufficient to neutralize P. falciparum parasites in vitro. This viral vectored vaccine regime is thus a leading approach for the induction of strong cellular and humoral immunogenicity against difficult disease targets in humans. Further studies are required to assess whether this strategy can achieve protective efficacy against blood-stage malaria infection.
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Affiliation(s)
- Susanne H Sheehy
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, University of Oxford, Churchill Hospital, Oxford, UK.
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Duncan CJA, Sheehy SH, Ewer KJ, Douglas AD, Collins KA, Halstead FD, Elias SC, Lillie PJ, Rausch K, Aebig J, Miura K, Edwards NJ, Poulton ID, Hunt-Cooke A, Porter DW, Thompson FM, Rowland R, Draper SJ, Gilbert SC, Fay MP, Long CA, Zhu D, Wu Y, Martin LB, Anderson CF, Lawrie AM, Hill AVS, Ellis RD. Impact on malaria parasite multiplication rates in infected volunteers of the protein-in-adjuvant vaccine AMA1-C1/Alhydrogel+CPG 7909. PLoS One 2011; 6:e22271. [PMID: 21799809 PMCID: PMC3142129 DOI: 10.1371/journal.pone.0022271] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 06/22/2011] [Indexed: 01/10/2023] Open
Abstract
Background Inhibition of parasite growth is a major objective of blood-stage malaria vaccines. The in vitro assay of parasite growth inhibitory activity (GIA) is widely used as a surrogate marker for malaria vaccine efficacy in the down-selection of candidate blood-stage vaccines. Here we report the first study to examine the relationship between in vivo Plasmodium falciparum growth rates and in vitro GIA in humans experimentally infected with blood-stage malaria. Methods In this phase I/IIa open-label clinical trial five healthy malaria-naive volunteers were immunised with AMA1/C1-Alhydrogel+CPG 7909, and together with three unvaccinated controls were challenged by intravenous inoculation of P. falciparum infected erythrocytes. Results A significant correlation was observed between parasite multiplication rate in 48 hours (PMR) and both vaccine-induced growth-inhibitory activity (Pearson r = −0.93 [95% CI: −1.0, −0.27] P = 0.02) and AMA1 antibody titres in the vaccine group (Pearson r = −0.93 [95% CI: −0.99, −0.25] P = 0.02). However immunisation failed to reduce overall mean PMR in the vaccine group in comparison to the controls (vaccinee 16 fold [95% CI: 12, 22], control 17 fold [CI: 0, 65] P = 0.70). Therefore no impact on pre-patent period was observed (vaccine group median 8.5 days [range 7.5–9], control group median 9 days [range 7–9]). Conclusions Despite the first observation in human experimental malaria infection of a significant association between vaccine-induced in vitro growth inhibitory activity and in vivo parasite multiplication rate, this did not translate into any observable clinically relevant vaccine effect in this small group of volunteers. Trial Registration ClinicalTrials.gov [NCT00984763]
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Affiliation(s)
- Christopher J A Duncan
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, University of Oxford, Oxford, United Kingdom.
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