title: Assessing stability and assembly of the hepatitis B surface antigen into virus-like particles during down-stream processing.
abstract: The hepatitis B surface antigen (HBsAg) is a recombinant protein-based vaccine being able to form virus-like particles (VLPs). HBsAg is mainly produced using yeast-based expression systems, however, recent results strongly suggest that VLPs are not formed within the yeast cells during the cultivation but are formed in a gradual manner during the following down-stream procedures. VLPs are also not detectable during the first down-stream steps including mechanical and EDTA/detergent-assisted cell destruction. Moreover, VLPs are not detectable in the cell lysate treated with polyethylene glycol and colloidal silica. The first VLP resembling structures appear after elution of HBsAg from colloidal silica to which it binds through hydrophobic interaction. These first VLP resembling structures are non-symmetrical as well as heterodisperse and exhibit a high tendency toward cluster formation presumably because of surface exposed hydrophobic patches. More symmetrical and monodisperse VLPs appear after the following ion-exchange and size-exclusion chromatography most likely as the result of buffer changes during these purification steps (toward more neutral pH and less salt). Final treatment of the VLPs with the denaturant KSCN at moderate concentrations with following KSCN removal by dialysis does not cause unfolding and VLP disassembly but results in a re- and fine-structuring of the VLP surface topology.
authors.affiliation: Leibniz University of Hannover, Technical Chemistry, Life Science, Callinstr. 5, 30167 Hannover, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Zahid
authors.affiliation: Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Lünsdorf
authors.affiliation: Leibniz University of Hannover, Technical Chemistry, Life Science, Callinstr. 5, 30167 Hannover, Germany; Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany. Electronic address: ursula.rinas@helmholtz-hzi.de.
authors.forename: Ursula
authors.initials: U
authors.lastname: Rinas
mesh_terms: D006514:Hepatitis B Surface Antigens / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D017325:Hepatitis B Vaccines / Q000737:chemistry* / Q000302:isolation & purification; D006801:Humans; D055503:Protein Multimerization; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013678:Technology, Pharmaceutical; D058425:Vaccines, Virus-Like Particle / Q000737:chemistry* / Q000302:isolation & purification; D022701:Virosomes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines; D011994:Recombinant Proteins; D058425:Vaccines, Virus-Like Particle; D022701:Virosomes
keywords: Aerosil-380; Hepatitis B surface antigen virus-like particles; Ion-exchange chromatography; Purification; Size-exclusion chromatography; Transmission electron microscopy; Vaccine