title: Plasmodium vivax: comparison of immunogenicity among proteins expressed in the cell-free systems of Escherichia coli and wheat germ by suspension array assays.
abstract: BACKGROUND
  In vitro cell-free systems for protein expression with extracts from prokaryotic (Escherichia coli) or eukaryotic (wheat germ) cells coupled to solid matrices have offered a valid approach for antigen discovery in malaria research. However, no comparative analysis of both systems is presently available nor the usage of suspension array technologies, which offer nearly solution phase kinetics.
  
  
  METHODS
  Five Plasmodium vivax antigens representing leading vaccine candidates were expressed in the E. coli and wheat germ cell-free systems at a 50 μl scale. Products were affinity purified in a single-step and coupled to luminex beads to measure antibody reactivity of human immune sera.
  
  
  RESULTS
  Both systems readily produced detectable proteins; proteins produced in wheat germ, however, were mostly soluble and intact as opposed to proteins produced in E. coli, which remained mostly insoluble and highly degraded. Noticeably, wheat germ proteins were recognized in significantly higher numbers by sera of P. vivax patients than identical proteins produced in E. coli.
  
  
  CONCLUSIONS
  The wheat germ cell-free system offers the possibility of expressing soluble P. vivax proteins in a small-scale for antigen discovery and immuno-epidemiological studies using suspension array technology.
authors.affiliation: Barcelona Centre for International Health Research (CRESIB), Hospital Clinic/IDIBAPS, Universitat de Barcelona, Roselló 153, 1a planta, 08036, Barcelona, Spain.
authors.forename: Edmilson
authors.initials: E
authors.lastname: Rui
authors.forename: Carmen
authors.initials: C
authors.lastname: Fernandez-Becerra
authors.forename: Satoru
authors.initials: S
authors.lastname: Takeo
authors.forename: Sergi
authors.initials: S
authors.lastname: Sanz
authors.forename: Marcus V G
authors.initials: MV
authors.lastname: Lacerda
authors.forename: Takafumi
authors.initials: T
authors.lastname: Tsuboi
authors.forename: Hernando A
authors.initials: HA
authors.lastname: del Portillo
mesh_terms: D000328:Adult; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000096:biosynthesis* / Q000276:immunology* / Q000302:isolation & purification; D002474:Cell-Free System; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D010966:Plasmodium vivax / Q000276:immunology*; D015800:Protozoan Proteins / Q000096:biosynthesis* / Q000276:immunology* / Q000302:isolation & purification; D014908:Triticum / Q000378:metabolism
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D015800:Protozoan Proteins