Koletzki D, Biel S S, Meisel H, Nugel E, Gelderblom H R, Krüger D H, Ulrich R
Institute of Virology, Charité Medical School, Humboldt University, Berlin, Germany.
Biol Chem. 1999 Mar;380(3):325-33. doi: 10.1515/BC.1999.044.
Core particles of the hepatitis B virus (HBV) potentiate the immune response against foreign epitopes presented on their surface. Potential insertion sites in the monomeric subunit of the HBV core protein were previously identified at the N- and C-terminus and in the immunodominant c/e1 region. In a C-terminally truncated core protein these sites were used to introduce the entire 120 amino acid (aa)-long potentially immunoprotective region of the hantavirus (serotype Puumala) nucleocapsid protein. The N- and C-terminal fusion products were unable to form core-like particles in detectable amounts. However, a suppressable stop codon located between the HBV core and the C-terminally fused hantavirus sequence restored the ability to form particles ('mosaic particles'); in contrast to the C-terminal fusion product the mosaic construct allowed the formation of particles built up by the core protein itself and the HBV core-Puumala nucleocapsid-readthrough protein. The mosaic particles exposed the 120 aa region of the PUU nucleocapsid protein on their surface as demonstrated by ELISA and immuno electron microscopy applying different monoclonal antibodies. Insertion of the hantaviral sequence into the c/e1 region not only allowed the formation of chimeric particles, but again the surface accessibility of the sequence. HBV core antigenicity itself was, however, reduced in the particles carrying insertions in the c/e1 region, probably due to a masking effect of the 120 aa long insert.
乙型肝炎病毒（HBV）的核心颗粒可增强针对其表面呈现的外来表位的免疫反应。先前已在HBV核心蛋白的单体亚基中的N端和C端以及免疫显性c/e1区域鉴定出潜在的插入位点。在C端截短的核心蛋白中，这些位点用于引入汉坦病毒（普马拉血清型）核衣壳蛋白的整个120个氨基酸（aa）长的潜在免疫保护区域。N端和C端融合产物无法形成可检测量的核心样颗粒。然而，位于HBV核心与C端融合的汉坦病毒序列之间的一个可抑制的终止密码子恢复了形成颗粒的能力（“嵌合颗粒”）；与C端融合产物不同，嵌合构建体允许形成由核心蛋白本身和HBV核心-普马拉核衣壳通读蛋白组成的颗粒。通过ELISA和应用不同单克隆抗体的免疫电子显微镜证明，嵌合颗粒在其表面暴露了PUU核衣壳蛋白的120个氨基酸区域。将汉坦病毒序列插入c/e1区域不仅允许形成嵌合颗粒，而且再次使该序列具有表面可及性。然而，在c/e1区域携带插入片段的颗粒中，HBV核心抗原性本身降低了，这可能是由于120个氨基酸长的插入片段的掩盖作用。
