Structure-Guided Design of CD4 T cell Memory-Enhanced rHA H7N9 Influenza Vaccine

摘要 常规流感暴露和疫苗接种产生的交叉保护免疫力不足， 新型禽流感。这加剧了人们对可能导致大量严重疾病的流行病的担忧 和死亡率之间的关系。H7N9禽流感对人类健康构成威胁， 自2013年出现以来，在每年的流行浪潮中一直观察到其高病死率。 病毒适应性增加人传人的可能性引起了人们对一种病毒的担忧。 H7N9流感病毒大流行。 H7N9流感HA在自然感染和疫苗接种中引起弱中和抗体应答。到 为H7N9流感大流行做好准备，疫苗策略克服了 需要H7N9 HA。我们假设对H7N9 HA的更强的CD4 + T细胞应答将支持H7N9 HA的免疫应答。 改善的血凝抑制（HI）抗体应答。为了解决这个问题，我们建议 使用结构指导方法将季节性HA特异性CD4 + T细胞表位引入H7N9 HA， 以产生能够通过诱导CD4 + T细胞来引发保护性HI应答的新型免疫原， 记忆所提出的研究基于我们先前的工作，表明H3-HA306 - 318 CD4 + T细胞 引入H7N9 HA中相应位点的表位增强效应T细胞和抗体免疫 这些抗体表位可以在保持自然感染中遇到的中和抗体表位的同时产生应答。 在此，我们建议将更多的记忆性CD4 + T细胞表位引入现有的优化的H7-HA中， 因为识别H3-HA306 - 318表位的CD4 + T细胞的频率在个体之间不同 这取决于他们的季节性流感暴露史。目标1将评价由以下组成的新型HA： 不同数量的工程化CD4 + T细胞表位。一个新的HA包含最少的工程 最接近野生型H7N9生物物理特性的季节性HA CD4 + T细胞表位 HA，并证明增强小鼠和人类的免疫应答超过野生型H7N9 HA将是 选择继续进行目标2的完善研究。在目标2中，我们将减少 从目标1中出现的免疫原，以产生一种改进的设计， 保护性免疫力，同时更紧密地保留野生型H7的结构和生物物理特性， ha.较低突变负荷的益处将使对中和抗体靶标的干扰最小化 和改进的可制造性。拟议的研究将确定一个主要候选人， 突变负荷和最大免疫原性和保护效力，可用于IND启动 在这个合作伙伴计划结束时进行研究。

ABSTRACT Routine influenza exposure and vaccination generate inadequate cross-protective immunity against novel avian influenza. This fuels concerns for pandemics that may cause high numbers of severe illness and deaths in immune naïve populations. Avian H7N9 influenza poses a threat to human health because of its high case fatality rate consistently observed in annual epidemic waves since it emergence in 2013. The potential for virus adaptations that increase human-to-human transmissibility raises concern for an H7N9 influenza virus pandemic. H7N9 influenza HA elicits weak neutralizing antibody responses in natural infection and vaccination. To prepare for an H7N9 influenza pandemic, vaccine strategies that overcome the poor immunogenicity of H7N9 HA are needed. We hypothesize that a stronger CD4+ T cell response to H7N9 HA will support an improved hemagglutination inhibition (HI) antibody response. To address this hypothesis, we propose to introduce seasonal HA-specific CD4+ T cell epitopes into H7N9 HA, using a structure-guided approach, to produce a novel immunogen capable of priming protective HI responses by inducing CD4+ T cell memory. The proposed studies are grounded in our prior work showing that the H3-HA306-318 CD4+ T cell epitope introduced into the corresponding site in H7N9 HA boosts effector T cell and antibody immune responses while preserving neutralizing antibody epitopes that would be encountered in natural infection. Here, we propose to introduce more memory CD4+ T cell epitopes into the existing optimized H7-HA because the frequency of CD4+ T cells that recognize the H3-HA306-318 epitope varies among individuals depending on their history of seasonal influenza exposure. Aim 1 will evaluate novel HAs composed of different numbers of engineered CD4+ T cell epitopes. A new HA containing the fewest engineered seasonal HA CD4+ T cell epitopes that best approximates the biophysical properties of wild type H7N9 HA and demonstrates enhanced mouse and human immune responses over wild type H7N9 HA will be selected to go forward to Aim 2 refinement studies. In Aim 2, we will reduce the mutational load of the immunogen that emerges from Aim 1 to generate an improved design that maintains the gain in protective immunity while more closely preserving structural and biophysical properties of wild type H7- HA. The benefits of a lower mutational load will be minimized perturbation to neutralizing antibody targets and improved manufacturability. The proposed studies will identify a lead candidate with minimum mutational load and maximal immunogenicity and protective efficacy that is ready for IND enabling studies by the end of this Partnerships program.