scholarly journals Phase 1 randomized controlled trial to evaluate the safety and immunogenicity of recombinant Pichia pastoris-expressed Plasmodium falciparum apical membrane antigen 1 (PfAMA1-FVO [25-545]) in healthy Malian adults in Bandiagara

2016 ◽  
Vol 15 (1) ◽  
Author(s):  
Mahamadou A. Thera ◽  
Drissa Coulibaly ◽  
Abdoulaye K. Kone ◽  
Ando B. Guindo ◽  
Karim Traore ◽  
...  
Keyword(s):  
Randomized Controlled Trial ◽  
Plasmodium Falciparum ◽  
Pichia Pastoris ◽  
Apical Membrane ◽  
Controlled Trial ◽  
Phase 1 ◽  
Apical Membrane Antigen 1 ◽  
Randomized Controlled ◽  
Apical Membrane Antigen ◽  
Recombinant Pichia Pastoris

scholarly journals Phase 1 Clinical Trial of Apical Membrane Antigen 1: an Asexual Blood-Stage Vaccine for Plasmodium falciparum Malaria

2005 ◽  
Vol 73 (6) ◽  
pp. 3677-3685 ◽  
Author(s):  
Elissa M. Malkin ◽  
David J. Diemert ◽  
Julie H. McArthur ◽  
John R. Perreault ◽  
Aaron P. Miles ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Vaccine ◽  
Vaccine Candidate ◽  
Apical Membrane ◽  
Phase 1 ◽  
Blood Stage ◽  
Enzyme Linked Immunosorbent Assay ◽  
Apical Membrane Antigen 1 ◽  
Apical Membrane Antigen ◽  
Microscopic Evaluation

ABSTRACT Apical membrane antigen 1 (AMA1), a polymorphic merozoite surface protein, is a leading blood-stage malaria vaccine candidate. A phase 1 trial was conducted with 30 malaria-naïve volunteers to assess the safety and immunogenicity of the AMA1-C1 malaria vaccine. AMA1-C1 contains an equal mixture of recombinant proteins based on sequences from the FVO and 3D7 clones of Plasmodium falciparum. The proteins were expressed in Pichia pastoris and adsorbed on Alhydrogel. Ten volunteers in each of three dose groups (5 μg, 20 μg, and 80 μg) were vaccinated in an open-label study at 0, 28, and 180 days. The vaccine was well tolerated, with pain at the injection site being the most commonly observed reaction. Anti-AMA1 immunoglobulin G (IgG) was detected by enzyme-linked immunosorbent assay (ELISA) in 15/28 (54%) volunteers after the second immunization and in 23/25 (92%) after the third immunization, with equal reactivity to both AMA1-FVO and AMA1-3D7 vaccine components. A significant dose-response relationship between antigen dose and antibody response by ELISA was observed, and the antibodies were predominantly of the IgG1 isotype. Confocal microscopic evaluation of sera from vaccinated volunteers demonstrated reactivity with P. falciparum schizonts in a pattern similar to native parasite AMA1. Antigen-specific in vitro inhibition of both FVO and 3D7 parasites was achieved with IgG purified from sera of vaccinees, demonstrating biological activity of the antibodies. To our knowledge, this is the first AMA1 vaccine candidate to elicit functional immune responses in malaria-naïve humans, and our results support the further development of this vaccine.

scholarly journals Posttranslational Modification of Recombinant Plasmodium falciparum Apical Membrane Antigen 1: Impact on Functional Immune Responses to a Malaria Vaccine Candidate

2005 ◽  
Vol 73 (7) ◽  
pp. 3963-3970 ◽  
Author(s):  
Birgitte Giersing ◽  
Kazutoyo Miura ◽  
Richard Shimp ◽  
Jin Wang ◽  
Hong Zhou ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Pichia Pastoris ◽  
Posttranslational Modification ◽  
Vaccine Candidate ◽  
Apical Membrane ◽  
Expression System ◽  
Apical Membrane Antigen 1 ◽  
E Coli ◽  
Apical Membrane Antigen ◽  
Significant Difference

ABSTRACT Recombinant apical membrane antigen 1 (AMA1) is a leading vaccine candidate for Plasmodium falciparum malaria, as antibodies against recombinant P. falciparum AMA1 (PfAMA1) interrupt merozoite invasion into erythrocytes. In order to investigate the role of posttranslational modification in modulating the functional immune response to recombinant AMA1, two separate alleles of PfAMA1 (FVO and 3D7), in which native N-glycosylation sites have been mutated, were produced using Escherichia coli and a Pichia pastoris expression system. Recombinant Pichia pastoris AMA1-FVO (PpAMA1-FVO) and PpAMA1-3D7 are O-linked glycosylated, and 45% of PpAMA1-3D7 is nicked, though all four recombinant molecules react with conformation-specific monoclonal antibodies. To address the immunological effect of O-linked glycosylation, we compared the immunogenicity of E. coli AMA1-FVO (EcAMA1-FVO) and PpAMA1-FVO antigens, since both molecules are intact. The effect of antigen nicking was then investigated by comparing the immunogenicity of EcAMA1-3D7 and PpAMA1-3D7. Our data demonstrate that there is no significant difference in the rabbit antibody titer elicited towards EcAMA1-FVO and PpAMA1-FVO or to EcAMA1-3D7 and PpAMA1-3D7. Furthermore, we have demonstrated that recombinant AMA1 (FVO or 3D7), whether expressed and refolded from E. coli or produced from the Pichia expression system, is equivalent and mimics the functionality of the native protein in in vitro growth inhibition assay experiments. We conclude that in the case of recombinant AMA1, the E. coli- and P. pastoris-derived antigens are immunologically and functionally equivalent and are unaffected by the posttranslational modification resulting from expression in these two systems.

scholarly journals The Most Polymorphic Residue on Plasmodium falciparum Apical Membrane Antigen 1 Determines Binding of an Invasion-Inhibitory Antibody

2006 ◽  
Vol 74 (5) ◽  
pp. 2628-2636 ◽  
Author(s):  
A. M. Coley ◽  
K. Parisi ◽  
R. Masciantonio ◽  
J. Hoeck ◽  
J. L. Casey ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Apical Membrane ◽  
Site Directed Mutagenesis ◽  
Supporting Evidence ◽  
Inhibitory Antibody ◽  
Apical Membrane Antigen 1 ◽  
Apical Membrane Antigen ◽  
Immune Pressure ◽  
Polymorphic Residue

ABSTRACT Apical membrane antigen 1 (AMA1) is currently one of the leading malarial vaccine candidates. Anti-AMA1 antibodies can inhibit the invasion of erythrocytes by Plasmodium merozoites and prevent the multiplication of blood-stage parasites. Here we describe an anti-AMA1 monoclonal antibody (MAb 1F9) that inhibits the invasion of Plasmodium falciparum parasites in vitro. We show that both reactivity of MAb 1F9 with AMA1 and MAb 1F9-mediated invasion inhibition were strain specific. Site-directed mutagenesis of a fragment of AMA1 displayed on M13 bacteriophage identified a single polymorphic residue in domain I of AMA1 that is critical for MAb 1F9 binding. The identities of all other polymorphic residues investigated in this domain had little effect on the binding of the antibody. Examination of the P. falciparum AMA1 crystal structure localized this residue to a surface-exposed α-helix at the apex of the polypeptide. This description of a polymorphic inhibitory epitope on AMA1 adds supporting evidence to the hypothesis that immune pressure is responsible for the polymorphisms seen in this molecule.

scholarly journals High-Level Expression of Plasmodium vivax Apical Membrane Antigen 1 (AMA-1) in Pichia pastoris: Strong Immunogenicity in Macaca mulatta Immunized with P. vivax AMA-1 and Adjuvant SBAS2

1999 ◽  
Vol 67 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Clemens H. M. Kocken ◽  
Martin A. Dubbeld ◽  
Annemarie Van Der Wel ◽  
Jack T. Pronk ◽  
Andrew P. Waters ◽  
...  
Keyword(s):  
Pichia Pastoris ◽  
Plasmodium Vivax ◽  
Apical Membrane ◽  
Gel Filtration ◽  
Methylotrophic Yeast ◽  
Enzyme Linked Immunosorbent Assay ◽  
Control Group ◽  
Apical Membrane Antigen 1 ◽  
Apical Membrane Antigen ◽  
High Level

ABSTRACT The apical membrane antigen 1 (AMA-1) family is a promising family of malaria blood-stage vaccine candidates that have induced protection in rodent and nonhuman primate models of malaria. Correct conformation of the protein appears to be essential for the induction of parasite-inhibitory responses, and these responses appear to be primarily antibody mediated. Here we describe for the first time high-level secreted expression (over 50 mg/liter) of thePlasmodium vivax AMA-1 (PV66/AMA-1) ectodomain by using the methylotrophic yeast Pichia pastoris. To prevent nonnative glycosylation, a conservatively mutagenized PV66/AMA-1 gene (PV66Δglyc) lacking N-glycosylation sites was also developed. Expression of the PV66Δglyc ectodomain yielded similar levels of a homogeneous product that was nonglycosylated and was readily purified by ion-exchange and gel filtration chromatographies. Recombinant PV66Δglyc43–487 was reactive with conformation-dependent monoclonal antibodies. With the SBAS2 adjuvant,Pichia-expressed PV66Δglyc43–487 was highly immunogenic in five rhesus monkeys, inducing immunoglobulin G enzyme-linked immunosorbent assay titers in excess of 1:200,000. This group of monkeys had a weak trend showing lower cumulative parasite loads following a Plasmodium cynomolgi infection than in the control group.

scholarly journals Group versus individual antenatal and first year postpartum care: Study protocol for a multi-country cluster randomized controlled trial in Kenya and Nigeria

2019 ◽  
Vol 2 ◽  
pp. 56 ◽  
Author(s):  
Mark M. Kabue ◽  
Lindsay Grenier ◽  
Stephanie Suhowatsky ◽  
Jaiyeola Oyetunji ◽  
Emmanuel Ugwa ◽  
...  
Keyword(s):  
Health Care ◽  
Randomized Controlled Trial ◽  
Data Collection ◽  
Pregnant Women ◽  
Controlled Trial ◽  
Phase 1 ◽  
First Year ◽  
Phase 2 ◽  
Randomized Controlled ◽  
Cluster Randomized

Background: Antenatal care (ANC) in many low- and middle-income countries is under-utilized and of sub-optimal quality. Group ANC (G-ANC) is an intervention designed to improve the experience and provision of ANC for groups of women (cohorts) at similar stages of pregnancy. Methods: A two-arm, two-phase, cluster randomized controlled trial (cRCT) (non-blinded) is being conducted in Kenya and Nigeria. Public health facilities were matched and randomized to either standard individual ANC (control) or G-ANC (intervention) prior to enrollment. Participants include pregnant women attending first ANC at gestational age <24 weeks, health care providers, and sub-national health managers. Enrollment ended in June 2017 for both countries. In the intervention arm, pregnant women are assigned to cohorts at first ANC visit and receive subsequent care together during five meetings facilitated by a health care provider (Phase 1). After birth, the same cohorts meet four times over 12 months with their babies (Phase 2). Data collection was performed through surveys, clinical data extraction, focus group discussions, and in-depth interviews. Phase 1 data collection ended in January 2018 and Phase 2 concludes in November 2018. Intention-to-treat analysis will be used to evaluate primary outcomes for Phases 1 and 2: health facility delivery and use of a modern method of family planning at 12 months postpartum, respectively. Data analysis and reporting of results will be consistent with norms for cRCTs. General estimating equation models that account for clustering will be employed for primary outcome analyzes. Results: Overall 1,075 and 1,013 pregnant women were enrolled in Nigeria and Kenya, respectively. Final study results will be available in February 2019. Conclusions: This is the first cRCT on G-ANC in Africa. It is among the first to examine the effects of continuing group care through the first year postpartum. Registration: Pan African Clinical Trials Registry PACTR201706002254227 May 02, 2017

Sign in / Sign up

Export Citation Format

Share Document