title: [Development of the recombinant SAG1 antigen of Toxoplasma gondii by high-density fermentation and identification of its immunoreactivity].
abstract: OBJECTIVE
  To develop a technology for production of recombinant SAG1 of Toxoplasma gondii (T.g) in batches.
  
  
  METHODS
  The rSAG1 of T.g was expressed in E.coli by high-density fermentation and purified by Sephadex G-75 column chromatography after Ni-NTA agarose at native condition. The activity of rSAG1 and its efficacy in T.g diagnosis were identified by Western blotting and ELISA, respectively.
  
  
  RESULTS
  The optical density (OD) of the bacteria reached 20.21 after induction, and 300 g bacteria were harvested from 11.5 L broth. The rSAG1 was highly expressed in E.coli as a fusion protein, accounting for about 25.82% of the total bacterial protein. The purity of rSAG1 reached 98.54% after purification by Ni-NTA combined with Sephadex G-75 column chromatography. Western blotting revealed a distinct band reacting with the sera of rabbits vaccinated by T.g. Twenty-four of the 25 sera of mice infected with T.g and 36 of the 38 sera of human subjects with IgG antibody against T.g were detected by rSAG1-ELISA.
  
  
  CONCLUSIONS
  A large-scale production of immunoreactive SAG1 of T.g is developed by high-density fermentation and purification with Ni-NTA combined with Sephadex G-75 column chromatography.
authors.affiliation: Department of Parasitology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou 510515, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.forename: Hui
authors.initials: H
authors.lastname: Yan
authors.forename: Bai-hong
authors.initials: BH
authors.lastname: Chen
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.forename: Xiao-guang
authors.initials: XG
authors.lastname: Chen
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D000954:Antigens, Surface / Q000276:immunology; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005285:Fermentation; D015800:Protozoan Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000276:immunology* / Q000302:isolation & purification; D014122:Toxoplasma / Q000276:immunology
chemical_list: D000953:Antigens, Protozoan; D000954:Antigens, Surface; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; C047168:SAG1 antigen, Toxoplasma