Biochemical and biophysical characterization of maize-derived HBsAg for the development of an oral vaccine.
Biochemical and biophysical characterization of maize-derived HBsAg for the development of an oral vaccine.
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DOI：
10.1016/j.abb.2015.10.015
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发表时间：
2015-12-15
影响因子：
3.9
通讯作者：
Howard JA
中科院分区：
文献类型：
--
作者：
Shah S;Hayden CA;Fischer ME;Rao AG;Howard JA
虽然自1982年以来就有了针对B型肝炎病毒（HBV）的疫苗，但据估计，每年有60万人死于HBV。一种负担得起的口服疫苗可以帮助减轻疾病负担，为此，在玉米中表达了乙型肝炎B表面抗原（HBsAg）。与全脂和己烷提取的材料相比，当通过CO2超临界流体提取（SFE）提取脂质时，经口递送的玉米材料在小鼠中诱导最强的免疫应答。本研究通过比较不同处理玉米材料中的活性成分，为这些免疫差异提供了生物化学和生物物理学基础。通过凝胶过滤、透射电子显微镜（TEM）、动态光散射（DLS）、UV-CD和荧光对纯化的玉米来源HBsAg进行生物物理表征。凝胶过滤表明，HBsAg形式的高阶寡聚体和TEM证明病毒样颗粒（VLP）的形成。与己烷或全脂材料相比，从SFE获得的VLP在形状和大小上更规则。紫外-圆二色光谱显示，超临界流体提取的HBsAg具有最大程度的α-螺旋结构。荧光实验也揭示了蛋白质构象的差异。这项工作确立了超临界流体处理的玉米材料作为一个可行的口服疫苗候选人，并推进了第一个口服亚单位疫苗的发展。
Although a vaccine against hepatitis B virus (HBV) has been available since 1982, it is estimated that 600,000 people die every year due to HBV. An affordable oral vaccine could help alleviate the disease burden and to this end the hepatitis B surface antigen (HBsAg) was expressed in maize. Orally delivered maize material induced the strongest immune response in mice when lipid was extracted by CO2 supercritical fluid extraction (SFE), compared to full fat and hexane-extracted material. The present study provides a biochemical and biophysical basis for these immunological differences by comparing the active ingredient in the differently treated maize material. Purified maize-derived HBsAg underwent biophysical characterization by gel filtration, transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-CD, and fluorescence. Gel filtration showed that HBsAg forms higher-order oligomers and TEM demonstrated virus-like particle (VLP) formation. The VLPs obtained from SFE were more regular in shape and size compared to hexane or full fat material. In addition, SFE-derived HBsAg showed the greatest extent of α-helical structure by far UV-CD spectrum. Fluorescence experiments also revealed differences in protein conformation. This work establishes SFE-treated maize material as a viable oral vaccine candidate and advances the development of the first oral subunit vaccine.