Production, Quality Control, Stability and Pharmacotoxicity of a Malaria Vaccine Comprising Three Highly Similar PfAMA1 Protein Molecules to Overcome Antigenic Variation

PLoS One. 2016 Oct 3;11(10):e0164053. doi: 10.1371/journal.pone.0164053. eCollection 2016.

Abstract

Plasmodium falciparum apical membrane antigen 1 (PfAMA1) is a leading asexual blood stage vaccine candidate for malaria. In preparation for clinical trials, three Diversity Covering (DiCo) PfAMA1 ectodomain proteins, designed to overcome the intrinsic polymorphism that is present in PfAMA1, were produced under Good Manufacturing Practice (GMP) in Pichia pastoris. Using identical methodology, the 3 strains were cultivated in 70-L scale fed-batch fermentations and PfAMA1-DiCos were purified by two chromatography steps, an ultrafiltration/diafiltration procedure and size exclusion chromatography, resulting in highly pure (>95%) PfAMA1-DiCo1, PfAMA1 DiCo2 and PfAMA1 DiCo3, with final yields of 1.8, 1.9 and 1.3 gram, respectively. N-terminal determinations showed that approximately 50% of each of the proteins lost 12 residues from their N-terminus, in accordance with SDS-PAGE (2 main bands) and MS-data. Under reducing conditions a site of limited proteolytic cleavage within a disulphide bonded region became evident. The three proteins quantitatively bound to the mAb 4G2 that recognizes a conformational epitope, suggesting proper folding of the proteins. The lyophilized Drug Product (1:1:1 mixture of PfAMA1-DiCo1, DiCo2, DiCo3) fulfilled all pre-set release criteria (appearance, dissolution rate, identity, purity, protein content, moisture content, sub-visible particles, immuno-potency (after reconstitution with adjuvant), abnormal toxicity, sterility and endotoxin), was stable in accelerated and real-time stability studies at -20°C for over 24 months. When formulated with adjuvants selected for clinical phase I evaluation, the Drug Product did not show adverse effect in a repeated-dose toxicity study in rabbits. The Drug Product has entered a phase Ia/Ib clinical trial.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Protozoan / immunology
  • Antigenic Variation*
  • Antigens, Protozoan / biosynthesis
  • Antigens, Protozoan / chemistry
  • Antigens, Protozoan / genetics
  • Antigens, Protozoan / immunology*
  • Female
  • Fermentation
  • Humans
  • Malaria Vaccines / administration & dosage
  • Malaria Vaccines / adverse effects
  • Malaria Vaccines / biosynthesis*
  • Malaria Vaccines / immunology*
  • Malaria, Falciparum / immunology
  • Malaria, Falciparum / prevention & control
  • Male
  • Membrane Proteins / biosynthesis
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / immunology*
  • Mice
  • Plasmodium falciparum / genetics
  • Plasmodium falciparum / immunology
  • Protein Stability
  • Protozoan Proteins / biosynthesis
  • Protozoan Proteins / chemistry
  • Protozoan Proteins / genetics
  • Protozoan Proteins / immunology*
  • Quality Control
  • Rabbits
  • Recombinant Proteins

Substances

  • Antibodies, Protozoan
  • Antigens, Protozoan
  • Malaria Vaccines
  • Membrane Proteins
  • Protozoan Proteins
  • Recombinant Proteins
  • apical membrane antigen I, Plasmodium

Grants and funding

The European (Malaria) Vaccine Initiative (http://www.euvaccine.eu/portfolio/project-index/ama1-dico)(BWF, StH, SoH, NH, JD, HM, AC, RK, RB, NW, ME, AWT, CHMK, EJR). Employees of the E(M)VI have been involved in the study design, data analysis, decision to publish and preparation of the manuscript. The Dutch Directorate-General for International Cooperation (DGIS)(www.euvaccine.eu)(SoH, NH). The Biomedical Primate Research Centre.(www.bprc.nl)(BWF, NW, ME, AWT, CHMK, EJR). Employees of the BPRC have been involved in the study design, data. One of the authors (RB) is employed by a commercial company (Nova Laboratories Ltd.). Nova Laboratories was paid for its activities (lyophilization).