A novel vaccine to prevent HCV infection and hence liver cancer

描述（由申请人提供）：估计全世界有1.7亿人和2000万美国人感染丙型肝炎病毒（HCV）。虽然有些人清除了感染，但许多人进展为慢性疾病，多年后可能会患肝癌。由于85%的肝癌与HCV相关，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HCV疫苗可以完全基于选择合成的B细胞表位来产生，这些表位被我们有幸拥有的已经存在的中和性单克隆抗HCV抗体所识别。我相信B细胞表位库的最佳选择是类肽而不是基于肽的。类肽是不限于20个天然氨基的N-取代甘氨酸的低聚物。侧链是简单的伯胺衍生物，与肽相比，可以便宜地购买数百种。类肽是蛋白酶抗性的，可以使用D氨基酸侧链（类肽杂合体），并且也可以是环状的。类肽在结构上类似于肽，但具有蛋白酶抗性，可以以更多样化的形状产生以适合B细胞受体的结合口袋，并且容易且廉价地大量合成。它们可以以107或更大的理论多样性和100万的“工作多样性”产生。它们是半抗原并且不需要含有T细胞表位。 最后，虽然HCV上的保守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，表位模拟物应该是免疫显性的，因为它们是半抗原，并且许多拷贝将连接到载体蛋白。载体蛋白将提供T细胞帮助以诱导针对类肽的稳健的高亲和力IgG应答。因此，T细胞帮助将不限于具有某些HLA单倍型的个体。我们已经证明，与载体蛋白缀合的类肽具有高度免疫原性，并且在模型系统中，它们可以诱导也与天然肽反应的抗体。 在本提案中，我们计划使用一组抗HCV的中和单克隆抗体（MAbs）进行筛查。然后将那些在筛选中呈阳性的类肽进行测序，批量合成，并测试其阻断HCV的天然E2蛋白与筛选MAb结合的能力。将那些在最低浓度下阻断的类肽与载体蛋白缀合（一起或单独），与明矾（一种批准用于人类的佐剂）混合，并用于免疫小鼠。将检测小鼠血清对E2的反应性。那些反应将进一步测试他们的能力，以中和一组HCV基因型。 尽管其他模拟物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物如肽、碳水化合物和抗独特型抗体相关的许多问题，并且其作为HCV和其他病原体的疫苗平台具有很大的前景。 公共卫生相关性：该赠款的目的是生产一种有效的丙型肝炎病毒疫苗，丙型肝炎病毒是肝癌的主要原因。我们的疫苗平台是基于称为类肽的合成结构，这些结构是由已知的中和病毒的现有单克隆抗体选择的。这些类肽将用这些抗体进行筛选，那些反应将与载体蛋白偶联并用于免疫小鼠。小鼠应该产生抗体，然后识别类肽和病毒。

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.