Institute of Medical Virology, Justus Liebig University, D-35392 Giessen, Germany.
J Hepatol. 2011 Jul;55(1):29-37. doi: 10.1016/j.jhep.2010.10.019. Epub 2010 Nov 28.
BACKGROUNDS & AIMS: The N-terminally myristoylated preS1 domain of the large hepatitis B surface protein (LHBs) mediates specific attachment of hepatitis B virus (HBV) to hepatocytes. Its B-cell epitopes leading to neutralization of infectivity are not yet characterized.
We inserted C- and N-terminal preS1 peptides into the most immunogenic region of HBV core particles, therewith immunized Balb/c mice and determined binding properties and neutralization potential of resulting antibodies in vitro.
The particles with preS1 inserts were highly immunogenic and the corresponding anti-preS antibodies strongly bound to HBV particles from chronic carriers infected with different HBV genotypes A-F. However, antibodies binding to the C-terminal part of preS1 did not neutralize HBV infectivity for susceptible hepatocyte cultures. In contrast, antibodies elicited by the complete N-terminal attachment site of preS1(2-48) strongly neutralized with an IC50<3μg/ml of total immunoglobulin. Interestingly, antibodies against the very N-terminal part of preS1(1-21) could not neutralize infectivity although this sequence contains the most conserved and essential part of the attachment site. These antibodies reacted well with non-myristoylated preS1 peptides but only weakly with myristoylated preS1 peptides, natural HBsAg or HBV.
N-terminal myristic acid obviously favors a topology of LHBs that makes the most essential part of the preS1 attachment site inaccessible for neutralizing antibodies, whereas antibodies to neighbouring sequences neutralized very well. Thus, addition of the preS1(2-48) peptide in a highly immunogenic form to the current hepatitis B vaccine may improve protective immunity and reduce selection of escape mutations.
乙型肝炎病毒（HBV）表面大蛋白（LHBs）的 N 端豆蔻酰化 preS1 结构域介导 HBV 与肝细胞的特异性附着。其导致中和感染性的 B 细胞表位尚未得到表征。
我们将 preS1 的 C 端和 N 端肽插入 HBV 核心颗粒最具免疫原性的区域，用此免疫 Balb/c 小鼠，并在体外测定产生的抗体的结合特性和中和潜力。
带有 preS1 插入物的颗粒具有高度的免疫原性，相应的抗-preS 抗体强烈结合来自不同 HBV 基因型 A-F 的慢性携带者的 HBV 颗粒。然而，结合 preS1 C 端的抗体不能中和易感肝细胞培养物中的 HBV 感染性。相比之下，由 preS1 的完整 N 端附着位点（2-48）诱导的抗体强烈中和，IC50<3μg/ml 的总免疫球蛋白。有趣的是，尽管该序列包含附着位点最保守和必需的部分，但针对 preS1（1-21）的非常 N 端部分的抗体不能中和感染性。这些抗体与非豆蔻酰化的 preS1 肽反应良好，但与豆蔻酰化的 preS1 肽、天然 HBsAg 或 HBV 反应较弱。
N 端豆蔻酸明显有利于 LHBs 的拓扑结构，使 preS1 附着位点的最关键部分无法被中和抗体识别，而相邻序列的抗体则能很好地中和。因此，以高度免疫原性的形式将 preS1（2-48）肽添加到当前的乙型肝炎疫苗中可能会改善保护性免疫并减少逃逸突变的选择。
