Iyer Seema, Robinett R S Robin, HogenEsch Harm, Hem Stanley L
Department of Industrial and Physical Pharmacy, Purdue University, Robert E. Heine Pharmacy Building, Room 124, 575 Stadium Mall Drive, West Lafayette, IN 47907-1336, USA.
Vaccine. 2004 Mar 29;22(11-12):1475-9. doi: 10.1016/j.vaccine.2003.10.023.
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 (1.7 microg/microg Al), which is the amount of HBsAg adsorbed at monolayer coverage and the adsorptive coefficient (6.0 ml/microg), 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 12 h in vitro exposure to interstitial fluid at 37 degrees C. Less than 1% of the adsorbed HBsAg in two commercial vaccines was eluted by in vitro exposure to interstitial fluid for 48 h at 37 degrees 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.
乙肝表面抗原（HBsAg）因其相关的脂质双层而与许多抗原不同，该脂质双层主要由磷脂组成。一般来说，磷酸基团通过配体交换强烈吸附在羟基化的矿物表面。本研究的目的是研究乙肝表面抗原吸附到氢氧化铝佐剂上的机制，重点是磷脂在这种吸附中的作用。氢氧化铝佐剂对HBsAg的吸附表现出高亲和力吸附等温线。使用朗缪尔方程计算吸附容量（1.7微克/微克铝），即单层覆盖时吸附的HBsAg量，以及吸附系数（6.0毫升/微克），它是吸附力强度的一种度量。吸附系数的相对较高值表明吸附是由于强大的吸引力。抗原的磷酸与佐剂的表面羟基之间的配体交换提供了最强的吸附机制。HBsAg的吸附容量不受离子强度增加的影响，表明静电吸引不是主要的吸附力。添加乙二醇也不影响吸附，表明疏水相互作用不是主要的吸附力。当暴露于组织液时，HBsAg对洗脱的抗性表明了吸附力的强度。在37℃下体外暴露于组织液12小时期间，吸附到模型疫苗中氢氧化铝佐剂上的HBsAg不到5%被洗脱。在37℃下体外暴露于组织液48小时后，两种商业疫苗中吸附的HBsAg不到1%被洗脱。因此，得出结论，氢氧化铝佐剂对HBsAg的吸附主要是由于HBsAg中的磷脂与氢氧化铝佐剂中的表面羟基之间的配体交换。
