Publications by authors named "Ripley Ballou"

Article Synopsis
  • * R21, when combined with Matrix-M, demonstrated strong immune responses and full protection against malaria challenges, and initial results suggest that lower doses of both R21 and RTS,S in AS01 may enhance immunity and protection.
  • * The research indicates that combining RTS,S with TRAP-based viral vectors may lead to improved immune responses without significant interference, highlighting the potential for multi-component vaccination strategies and the importance of testing low-dose vaccines in humans.
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The RTS,S/AS01 vaccine provides partial protection against infection but determinants of protection and/or disease are unclear. Previously, anti-circumsporozoite protein (CSP) antibody titers and blood RNA signatures were associated with RTS,S/AS01 efficacy against controlled human malaria infection (CHMI). By analyzing host blood transcriptomes from five RTS,S vaccination CHMI studies, we demonstrate that the transcript ratio MX2/GPR183, measured 1 day after third immunization, discriminates protected from non-protected individuals.

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Background: The 2014 West African outbreak of Ebola virus disease highlighted the urgent need to develop an effective Ebola vaccine.

Methods: We undertook 2 phase 1 studies assessing safety and immunogenicity of the viral vector modified vaccinia Ankara virus vectored Ebola Zaire vaccine (MVA-EBO-Z), manufactured rapidly on a new duck cell line either alone or in a heterologous prime-boost regimen with recombinant chimpanzee adenovirus type 3 vectored Ebola Zaire vaccine (ChAd3-EBO-Z) followed by MVA-EBO-Z. Adult volunteers in the United Kingdom (n = 38) and Senegal (n = 40) were vaccinated and an accelerated 1-week prime-boost regimen was assessed in Senegal.

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We assessed a combination multi-stage malaria vaccine schedule in which RTS,S/AS01B was given concomitantly with viral vectors expressing multiple-epitope thrombospondin-related adhesion protein (ME-TRAP) in a 0-month, 1-month, and 2-month schedule. RTS,S/AS01B was given as either three full doses or with a fractional (1/5th) third dose. Efficacy was assessed by controlled human malaria infection (CHMI).

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A malaria vaccine strategy targeting multiple lifecycle stages may be required to achieve a high level of efficacy. In two Phase IIa clinical trials, we tested immunogenicity and efficacy of RTS,S/AS01B administered alone, in a staggered regimen with viral-vectored vaccines or co-administered with viral-vectored vaccines. RTS,S/AS01B induces high titers of antibody against sporozoites and viral-vectored vaccines ChAd63 ME-TRAP and MVA ME-TRAP induce potent T cell responses against infected hepatocytes.

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Background: The safety and efficacy of vaccines to prevent Ebola virus disease (EVD) were unknown when the incidence of EVD was peaking in Liberia.

Methods: We initiated a randomized, placebo-controlled, phase 3 trial of the chimpanzee adenovirus 3 vaccine (ChAd3-EBO-Z) and the recombinant vesicular stomatitis virus vaccine (rVSV∆G-ZEBOV-GP) in Liberia. A phase 2 subtrial was embedded to evaluate safety and immunogenicity.

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The RTS,S candidate malaria vaccine can protect against controlled human malaria infection (CHMI), but how protection is achieved remains unclear. Here, we have analyzed longitudinal peripheral blood transcriptome and immunogenicity data from a clinical efficacy trial in which healthy adults received three RTS,S doses 4 weeks apart followed by CHMI 2 weeks later. Multiway partial least squares discriminant analysis (N-PLS-DA) of transcriptome data identified 110 genes that could be used in predictive models of protection.

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The blood-stage malaria vaccine FMP2.1/AS02A, comprised of recombinant Plasmodium falciparum apical membrane antigen 1 (AMA1) and the adjuvant system AS02A, had strain-specific efficacy against clinical malaria caused by P. falciparum with the vaccine strain 3D7 AMA1 sequence.

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RTS,S is an advanced malaria vaccine candidate and confers significant protection against infection in humans. Little is known about the molecular mechanisms driving vaccine immunity. Here, we applied a systems biology approach to study immune responses in subjects receiving three consecutive immunizations with RTS,S (RRR), or in those receiving two immunizations of RTS,S/AS01 following a primary immunization with adenovirus 35 (Ad35) (ARR) vector expressing circumsporozoite protein.

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Background: The need for a highly efficacious vaccine against Plasmodium falciparum remains pressing. In this controlled human malaria infection (CHMI) study, we assessed the safety, efficacy and immunogenicity of a schedule combining 2 distinct vaccine types in a staggered immunization regimen: one inducing high-titer antibodies to circumsporozoite protein (RTS,S/AS01B) and the other inducing potent T-cell responses to thrombospondin-related adhesion protein (TRAP) by using a viral vector.

Method: Thirty-seven healthy malaria-naive adults were vaccinated with either a chimpanzee adenovirus 63 and modified vaccinia virus Ankara-vectored vaccine expressing a multiepitope string fused to TRAP and 3 doses of RTS,S/AS01B (group 1; n = 20) or 3 doses of RTS,S/AS01B alone (group 2; n = 17).

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Background: Three full doses of RTS,S/AS01 malaria vaccine provides partial protection against controlled human malaria parasite infection (CHMI) and natural exposure. Immunization regimens, including a delayed fractional third dose, were assessed for potential increased protection against malaria and immunologic responses.

Methods: In a phase 2a, controlled, open-label, study of healthy malaria-naive adults, 16 subjects vaccinated with a 0-, 1-, and 2-month full-dose regimen (012M) and 30 subjects who received a 0-, 1-, and 7-month regimen, including a fractional third dose (Fx017M), underwent CHMI 3 weeks after the last dose.

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Based on Plasmodium falciparum (Pf) apical membrane antigen 1 (AMA1) from strain 3D7, the malaria vaccine candidate FMP2.1/AS02A showed strain-specific efficacy in a Phase 2 clinical trial in 400 Malian children randomized to 3 doses of the AMA1 vaccine candidate or control rabies vaccine on days 0, 30 and 60. A subset of 10 Pf(-) (i.

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Background: A vaccine to prevent infection and disease caused by Plasmodium vivax is needed both to reduce the morbidity caused by this parasite and as a key component in efforts to eradicate malaria worldwide. Vivax malaria protein 1 (VMP001), a novel chimeric protein that incorporates the amino- and carboxy- terminal regions of the circumsporozoite protein (CSP) and a truncated repeat region that contains repeat sequences from both the VK210 (type 1) and the VK247 (type 2) parasites, was developed as a vaccine candidate for global use.

Methods: We conducted a first-in-human Phase 1 dose escalation vaccine study with controlled human malaria infection (CHMI) of VMP001 formulated in the GSK Adjuvant System AS01B.

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Background: The ongoing Ebola outbreak led to accelerated efforts to test vaccine candidates. On the basis of a request by WHO, we aimed to assess the safety and immunogenicity of the monovalent, recombinant, chimpanzee adenovirus type-3 vector-based Ebola Zaire vaccine (ChAd3-EBO-Z).

Methods: We did this randomised, double-blind, placebo-controlled, dose-finding, phase 1/2a trial at the Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.

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Background: The 2014 west African Zaire Ebola virus epidemic prompted worldwide partners to accelerate clinical development of replication-defective chimpanzee adenovirus 3 vector vaccine expressing Zaire Ebola virus glycoprotein (ChAd3-EBO-Z). We aimed to investigate the safety, tolerability, and immunogenicity of ChAd3-EBO-Z in Malian and US adults, and assess the effect of boosting of Malians with modified vaccinia Ankara expressing Zaire Ebola virus glycoprotein and other filovirus antigens (MVA-BN-Filo).

Methods: In the phase 1, single-blind, randomised trial of ChAd3-EBO-Z in the USA, we recruited adults aged 18-65 years from the University of Maryland medical community and the Baltimore community.

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Methods: In an observer blind, phase 2 trial, 55 adults were randomized to receive one dose of Ad35.CS.01 vaccine followed by two doses of RTS,S/AS01 (ARR-group) or three doses of RTS,S/AS01 (RRR-group) at months 0, 1, 2 followed by controlled human malaria infection.

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Background: The West African outbreak of Ebola virus disease that peaked in 2014 has caused more than 11,000 deaths. The development of an effective Ebola vaccine is a priority for control of a future outbreak.

Methods: In this phase 1 study, we administered a single dose of the chimpanzee adenovirus 3 (ChAd3) vaccine encoding the surface glycoprotein of Zaire ebolavirus (ZEBOV) to 60 healthy adult volunteers in Oxford, United Kingdom.

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This phase II, randomized, double-blind study evaluated the immunogenicity of RTS,S vaccines containing Adjuvant System AS01 or AS02 as compared with non-adjuvanted RTS,S in healthy, malaria-naïve adults (NCT00443131). Thirty-six subjects were randomized (1:1:1) to receive RTS,S/AS01, RTS,S/AS02, or RTS,S/saline at months 0, 1, and 2. Antibody responses to Plasmodium falciparum circumsporozoite (CS) and hepatitis B surface (HBs) antigens were assessed and cell-mediated immune responses evaluated by flow cytometry using intracellular cytokine staining on peripheral blood mononuclear cells.

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In an attempt to improve the efficacy of the candidate malaria vaccine RTS,S/AS02, two studies were conducted in 1999 in healthy volunteers of RTS,S/AS02 in combination with recombinant Plasmodium falciparum thrombospondin-related anonymous protein (TRAP). In a Phase 1 safety and immunogenicity study, volunteers were randomized to receive TRAP/AS02 (N=10), RTS,S/AS02 (N=10), or RTS,S+TRAP/AS02 (N=20) at 0, 1 and 6-months. In a Phase 2 challenge study, subjects were randomized to receive either RTS,S+TRAP/AS02 (N=25) or TRAP/AS02 (N=10) at 0 and 1-month, or to a challenge control group (N=8).

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Introduction: The aetiology of acute exacerbations of chronic obstructive pulmonary disease (COPD) remains incompletely understood and strategies for treatment and prevention have not altered significantly for many years. Improved understanding of the role of respiratory pathogens in acute exacerbations of COPD (AECOPD) is required and the use of molecular microbiological techniques may lead to insights into host-pathogen interactions and the development of more targeted therapeutic approaches.

Methods And Analyses: Acute Exacerbation and Respiratory InfectionS in COPD (AERIS) is a longitudinal epidemiological study to assess how changes in the COPD airway microbiome contribute to the incidence and severity of AECOPD.

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Background: The FMP2.1/AS02A candidate malaria vaccine was tested in a Phase 2 study in Mali. Based on results from the first eight months of follow-up, the vaccine appeared well-tolerated and immunogenic.

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Background: The development of an asexual blood stage vaccine against Plasmodium falciparum malaria based on the major merozoite surface protein-1 (MSP1) antigen is founded on the protective efficacy observed in preclinical studies and induction of invasion and growth inhibitory antibody responses. The 42 kDa C-terminus of MSP1 has been developed as the recombinant protein vaccine antigen, and the 3D7 allotype, formulated with the Adjuvant System AS02A, has been evaluated extensively in human clinical trials. In preclinical rabbit studies, the FVO allele of MSP142 has been shown to have improved immunogenicity over the 3D7 allele, in terms of antibody titres as well as growth inhibitory activity of antibodies against both the heterologous 3D7 and homologous FVO parasites.

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Background: The RTS,S/AS malaria candidate vaccine is being developed with the intent to be delivered, if approved, through the Expanded Programme on Immunization (EPI) of the World Health Organization. Safety, immunogenicity and efficacy of the RTS,S/AS02(D) vaccine candidate when integrated into a standard EPI schedule for infants have been reported over a nine-month surveillance period. This paper describes results following 20 months of follow up.

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Unlabelled: Prevention of tuberculosis (TB) through vaccination would substantially reduce the global TB burden. Mtb72F/AS02 is a candidate TB vaccine shown to be immunogenic and well tolerated in PPD-negative adults. We evaluated the safety and immunogenicity of Mtb72F/AS02 in Mycobacterium-primed adults (BCG-vaccinated, or infected adults who had received post-exposure chemoprophylaxis or treatment for pulmonary TB disease).

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