title: Expression and purification of the recombinant HBcAg core particles derived from methyltrophic Pichia pastoris, and TEM and AFM of the core particles and their natural aggregates.
abstract: The recombinant hepatitis B virus core antigen (rHBcAg) core particles derived from Pichia pastoris were purified from a crude lysate of the yeast by three steps: Sephrose CL-4B chromatography, sucrose step-gradient ultracentrifugation and CsCl-isopycnic ultracentrifugation. Results of ELISA test and density analysis of CsCl-isopycnic ultracentrifugation indicate that the purified rHBcAg particles with HBcAg antigenicity mainly locate at the densities of 1.2576 and 1.3013 g.mL(-1), respectively. After purification, a portion of purified sample of rHBcAg particles was immediately subjected to detection using transmission electron microscopy (TEM) and atomic force microscopy (AFM), the remainder were kept in -20 degrees C for 1 month or longer. After 30 days, the sample of rHBcAg particles previously frozen was imaged by TEM and AFM. The detection results indicate that the stored rHBcAg particles aggregated into a string of beads. The above results suggested that the rHBcAg particles expressed and self-assembled in P. pastoris, which were stored at -20 degrees C, can gradually and naturally aggregate with storage time.
authors.affiliation: School of Life Science, Shanghai University, Shanghai 200444, PR China. hengc@ualberta.ca
authors.forename: Heng
authors.initials: H
authors.lastname: Chen
mesh_terms: D006512:Hepatitis B Core Antigens / Q000235:genetics / Q000302:isolation & purification* / Q000648:ultrastructure*; D006515:Hepatitis B virus / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D010843:Pichia; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000648:ultrastructure; D014461:Ultracentrifugation
chemical_list: D006512:Hepatitis B Core Antigens; D011994:Recombinant Proteins