Mechanism of adsorption of hepatitis B surface antigen by aluminum hydroxide adjuvant

Seema Iyer, R. S.Robin Robinett, Harm HogenEsch, Stanley L. Hem

Research output: Contribution to journalArticle

67 Scopus citations

Abstract

Hepatitis B surface antigen (HBsAg) differs from many antigens because of its associated lipid bilayer that is largely composed of phospholipids. In general, phosphate groups adsorb strongly to hydroxylated mineral surfaces by ligand exchange. The purpose of this study was to investigate the mechanism of adsorption of hepatitis B surface antigen to aluminum hydroxide adjuvant with emphasis on the role of phospholipids in this adsorption. The adsorption of HBsAg by aluminum hydroxide adjuvant exhibits a high affinity adsorption isotherm. The Langmuir equation was used to calculate the adsorptive capacity (1.7μg/μg Al), which is the amount of HBsAg adsorbed at monolayer coverage and the adsorptive coefficient (6.0ml/μg), which is a measure of the strength of the adsorption force. The relatively high value of the adsorptive coefficient indicates that adsorption is due to a strong attractive force. Ligand exchange between a phosphate of the antigen and a surface hydroxyl of the adjuvant provides the strongest adsorption mechanism. The adsorption capacity of HBsAg was not affected by increased ionic strength indicating that electrostatic attraction is not the predominant adsorption force. Adsorption was also not affected by the addition of ethylene glycol indicating that hydrophobic interactions were not the predominant adsorption force. The strength of the adsorption force was indicated by the resistance of HBsAg to elution when exposed to interstitial fluid. Less than 5% of the HBsAg adsorbed to aluminum hydroxide adjuvant in a model vaccine was eluted during a 12h in vitro exposure to interstitial fluid at 37°C. Less than 1% of the adsorbed HBsAg in two commercial vaccines was eluted by in vitro exposure to interstitial fluid for 48h at 37°C. Thus, it was concluded that adsorption of HBsAg by aluminum hydroxide adjuvant is predominantly due to ligand exchange between the phospholipids in HBsAg and surface hydroxyls in aluminum hydroxide adjuvant.

Original languageEnglish (US)
Pages (from-to)1475-1479
Number of pages5
JournalVaccine
Volume22
Issue number11-12
DOIs
StatePublished - Mar 29 2004
Externally publishedYes

Keywords

  • Adsorption of HBsAg by aluminum hydroxide adjuvant
  • Elution of HBsAg in interstitial fluid
  • Hepatitis B surface antigen
  • Ligand exchange

ASJC Scopus subject areas

  • Molecular Medicine
  • Immunology and Microbiology(all)
  • veterinary(all)
  • Public Health, Environmental and Occupational Health
  • Infectious Diseases

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