A novel vaccine to prevent HCV infection and hence liver cancer

描述(申请人提供)：全球估计有1.7亿人感染丙型肝炎病毒(丙型肝炎病毒)。虽然一些人的感染已经痊愈，但许多人发展为慢性病，几年后可能会患上肝癌。由于85%的肝癌与丙型肝炎病毒有关，如果通过接种疫苗可以避免感染，这将对肝癌的发病率产生重大影响。我的假设是，新的抗丙型肝炎病毒疫苗完全可以基于选择合成的B细胞表位来产生，这些表位被已经存在的中和抗丙型肝炎病毒抗体识别，我们幸运地拥有这些抗体。我认为B细胞表位文库的最佳选择是类肽而不是基于多肽的。类肽是N-取代的甘氨酸的低聚物，不限于20个天然氨基。侧链是简单的伯胺衍生物，与多肽相比，数百种侧链可以便宜地购买。类肽是抗蛋白酶的，可以使用D-氨基酸侧链(类肽-杂交体)，也可以是环状的。类肽在结构上与多肽相似，但对蛋白酶具有抵抗力，可以产生更多不同的形状，以适应B细胞受体的结合口袋，并且容易且廉价地大量合成。它们的理论多样性可以达到107或更高，而“工作多样性”可以达到100万。它们是半抗原，不需要包含T细胞表位。最后，虽然丙型肝炎病毒上保守的中和表位可能不是免疫显性的，或者可能是稀疏的，但在我们的平台中，表位模拟应该是免疫显性的，因为它们是半抗原，许多拷贝将附着在载体蛋白上。载体蛋白将为T细胞提供帮助，以诱导强大的、高亲和力的抗肽类免疫球蛋白反应。因此，T细胞帮助不会局限于具有某些人类白细胞抗原单倍型的个体。我们已经证明，与载体蛋白结合的类肽具有高度的免疫原性，在模型系统中，它们可以诱导也与天然多肽发生反应的抗体。在这项提案中，我们计划使用一组中和抗丙型肝炎病毒的单抗(MAb)进行筛查。那些在筛选中呈阳性的类肽将被测序，批量合成，并测试它们阻止丙型肝炎病毒天然E2蛋白与筛选单抗的结合的能力。那些在最低浓度下被阻断的将被(一起或单独)连接到载体蛋白，与明矾(一种批准用于人类的佐剂)混合，并用于免疫小鼠。将对小鼠血清进行针对E2的反应性测试。那些有反应的人将接受进一步的测试，以确定他们中和一组丙型肝炎病毒基因的能力。虽然其他模拟平台尚未取得巨大成功，但我们相信，类肽平台克服了与其他模拟平台相关的许多问题，如肽、碳水化合物和抗独特型抗体，并有望成为丙型肝炎病毒和其他病原体的疫苗平台。 与公共卫生相关：这笔赠款的目标是生产一种有效的丙型肝炎病毒疫苗，丙型肝炎病毒是导致肝癌的主要原因。我们的疫苗平台是基于一种称为类肽的合成结构，这种结构是由已知的中和病毒的现有单抗选择的。这些类肽将用这些抗体进行筛选，那些有反应的将与载体蛋白偶联，并用于免疫小鼠。小鼠应该制造抗体，然后同时识别类肽和病毒。

DESCRIPTION (provided by applicant): An estimated170 million people worldwide and 20 million Americans are infected with hepatitis C virus HCV). Although some individuals clear the infection, many progress to chronic disease and years later can get liver cancer. Since 85% of liver cancers are HCV-associated, if infection could be avoided by vaccination, this would have a major impact on the incidence of liver cancer. My hypothesis is that new vaccines against HCV can be generated based entirely on selecting synthetic B cell epitopes recognized by already-existing neutralizing monoclonal anti-HCV antibodies that we are fortunate to have. I believe that the best choice for a library of B cell epitopes is peptoid rather than peptide-based. Peptoids are oligomers of N-substituted glycines not restricted to the 20 natural amino. The side chains are simple primary amine derivatives, hundreds of which can be purchased inexpensively as compared to peptides. Peptoids are protease resistant, can use D amino acid side chains (peptoid-hybrids), and can also be cyclic. Peptoids are structurally similar to peptides but are protease resistant, can be created in more diverse shapes to fit into the binding pocket of B cell receptors, and are easily and inexpensively synthesized in large amounts. They can be generated with a theoretical diversity of 107 or greater and a "working diversity" of a million. They are haptens and need not contain T cell epitopes. Finally, while conserved neutralizing epitopes on HCV might not be immunodominant, or might be sparse, in our platform, epitope mimetics should be immunodominant since they are haptens and many copies will be attached to a carrier protein. The carrier protein will provide T cell help to induce robust, high affinity IgG responses against the peptoid. Hence, T cell help will not be restricted to individuals with certain HLA haplotypes. We have already shown that peptoids conjugated to carrier proteins are highly immunogenic and that, in a model system, they can induce antibodies that also react with the native peptide. In this proposal we plan to use a panel of neutralizing monoclonal antibodies (MAbs) against HCV for screening. Those peptoids that are positive in the screen will then be sequenced, synthesized in bulk, and tested for their ability to block the binding of the native E2 protein of HCV to the screening MAb Those that block at the lowest concentration will be conjugated (together or separately) to a carrier protein, mixed with alum (an adjuvant approved for humans), and used to immunize mice. The mouse sera will be tested for reactivity against E2. Those that react will be further tested for their ability to neutralize a panel of HCV genotypes. Although other mimetic platforms have not met with great success, we believe that the peptoid platform overcomes many of the problems associated with other mimetics such as peptides, carbohydrates and anti- idiotypic antibodies, and that it holds great promise as a vaccine platform for HCV and other pathogens. PUBLIC HEALTH RELEVANCE: The objective of this grant is to generate an effective vaccine against Hepatitis C virus, the major cause of liver cancer. Our vaccine platform is based on synthetic structures called peptoids that are selected by existing monoclonal antibodies that are already known neutralize the virus. These peptoids will be screened with these antibodies, and those that react will be coupled to carrier proteins and used to immunize mice. The mice should make antibodies that then both recognize both the peptoid and the virus.