Capsid-incorporation of HIV antigens as a novel adenovirus HIV vaccine approach

描述（由申请人提供）：尽管Ad载体对于疫苗应用具有许多潜在的优点，但是当前Ad疫苗的充分利用可能受到宿主抗载体免疫应答的限制。具体地，抗Ad体液免疫消除了随后施用Ad载体的有效性，混淆了编码的转基因的表达，从而实际上限制了可能通过加强效应而累积的增益。为了利用Ad载体的固有抗原性，我们开发了基于将免疫抗原表位直接掺入Ad衣壳的疫苗接种方法。这种新的范例是基于Ad呈递抗原作为衣壳的组分，而不是编码的转基因。将免疫原性肽并入Ad衣壳提供了潜在的优势。最值得注意的是，通过外源途径加工衣壳掺入的抗原应导致类似于天然Ad衣壳蛋白引起的应答的强烈体液应答。此外，由于抗Ad衣壳应答通过重复载体施用而增强，因此针对作为Ad衣壳的一部分的抗原表位的免疫应答也应通过重复施用而增强，从而允许加强。这些考虑表明，这种新的captain纳入抗原的方法可能会提供令人兴奋的潜力，实现基于广告的疫苗策略，规避与广告载体的主要限制。 实现这种方法的关键是定义腺病毒衣壳环境中抗原的最佳构型。为此，我们已经建立了几项关键技术，使我们能够实现我们的目标。特别是，我们已经开发了将异源肽表位纳入主要Ad衣壳蛋白六邻体的表面暴露结构域内的方法。我们已经开始确定预测这些结构域在六邻体中的功能效用的大小和结构因素。此外，我们已经开发了应用冷冻电子显微镜（cryoEM）单颗粒重建方法的方法，使我们能够以前所未有的亚纳米分辨率探索captase掺入肽的定位。基于这些技术，我们将能够建立衣壳环境中抗原位置/可及性与疫苗效力之间的关键相关性。 在这些已建立的特征的基础上，我们假设，Ad载体可以创建与新的captain纳入抗原，可以作为疫苗剂对HIV的动物模型。CryoEM引导的衣壳设计将被应用于开发具有最佳抗HIV免疫的优化载体。我们设想，我们提出的结构研究将提供补充信息，在体外测定和生物读数，从而使我们能够了解纳入HIV表位的功能决定因素。该项目将设计新的和创新的方法来制造艾滋病毒疫苗，以期防止艾滋病毒疾病的传播。

DESCRIPTION (provided by applicant): Despite the many potential advantages of Ad vectors for vaccine application, full utility of current Ad vaccines may be limited by the host anti-vector immune response. Specifically, the anti-Ad humoral immunity abrogates the effectiveness of subsequent administrations of the Ad vector, confounding expression of the encoded transgene, and thus practically restricting the gains that might be accrued via booster effect. In order to exploit the inherent antigenicity of the Ad vector we have developed a vaccination approach based on incorporation of the immunizing antigen epitope directly into the Ad capsid. This novel paradigm is based upon Ad presenting the antigen as a component of the capsid rather than an encoded transgene. Incorporation of immunogenic peptides into the Ad capsid offers potential advantages. Most noteworthy, the processing of the capsid incorporated antigen via the exogenous pathway should result in a strong humoral response akin to the response provoked by native Ad capsid proteins. In addition, since anti-Ad capsid responses are augmented by repeated vector administration, immune responses against antigenic epitopes that are part of the Ad capsid should be augmented by repeated administration as well, thus allowing boosting. These considerations suggest that this novel capsid-incorporated antigen approach may offer exciting potentials to realize Ad-based vaccine strategies that circumvent the major limitations associated with Ad vectors. Critical to the realization of this approach is to define the optimal configuration of antigen in the adenoviral capsid context. To this end, we have established several key technologies that will enable us to reach our goal. In particular, we have developed the means to incorporate heterologous peptide epitopes within the surface-exposed domains of the major Ad capsid protein hexon. We have begun to determine the size and structural factors that predicate functional utility of these domains in the hexon. In addition, we have developed the means to apply cryoelectron microscopy (cryoEM) single particle reconstruction methods to allow us to explore the capsid-incorporated peptide localization with unprecedented, subnanometer resolution. Based on these technologies, we will be able to establish the critical correlates between antigen locale/accessibility within the capsid context and vaccine efficacy. On the basis of these established feasibilities, we hypothesize that Ad vectors can be created with novel capsid-incorporated antigens that can serve as vaccine agents against HIV in animal models. CryoEM-guided capsid design will be applied to develop an optimized vector with optimal anti-HIV immunization. We envision that our proposed structural studies will provide complementary information to in vitro assays and biological readouts and thereby will enable us to understand the functional determinants of incorporated HIV epitopes. This project will design new and innovative methodologies to create HIV vaccines, in hopes of preventing the spread of HIV disease.