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

摘要 常规的流感暴露和疫苗接种产生的交叉保护免疫不足 新型禽流感。这加剧了人们对可能导致大量严重疾病的大流行的担忧 以及免疫幼稚人群中的死亡。禽流感H7N9对人类健康构成威胁 自2013年出现以来，其高病死率一直出现在每年的流行浪潮中。 病毒适应增加人与人之间的传播力的可能性引起了人们对 H7N9流感病毒大流行。 H7N9流感血凝素在自然感染和疫苗接种中诱导弱中和抗体反应。至 为H7N9流感大流行做好准备，克服H7N9流感免疫原性差的疫苗策略 需要H7N9 HA。我们假设，对H7N9 HA有更强的CD4+T细胞应答将支持 改进了血凝抑制(HI)抗体反应。为了解决这一假设，我们建议 将季节性HA特异性CD4+T细胞表位引入H7N9 HA，采用结构引导方法， 通过诱导CD4+T细胞诱导保护性HI反应的新型免疫原的研制 记忆。拟议的研究是基于我们之前的工作，表明H3-HA306-318 CD4+T细胞 H7N9 HA相应部位引入表位增强效应性T细胞和抗体免疫 在保留自然感染中可能遇到的中和抗体表位的同时，还能产生更多的反应。 在这里，我们建议在现有的优化的H7-HA中引入更多的记忆CD4+T细胞表位 因为识别H3-HA306-318表位的CD4+T细胞的频率因个体而异 这取决于他们的季节性流感接触史。目标1将评估小说由以下内容组成 不同数量的工程化CD4+T细胞表位。包含最少工程材料的新房委会 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，并展示了增强小鼠和人类对野生型H7N9 HA的免疫反应 被选中继续进行目标2的精细化研究。在目标2中，我们将减少 从目标1出现的免疫生成，以生成改进的设计，以保持在 保护性免疫，同时更紧密地保留了野生型H7- 哈哈。较低的突变负荷的好处将是对中和抗体靶标的干扰最小化 并改进了可制造性。拟议的研究将确定一名领先的候选人，至少 突变负荷和最大免疫原性以及为IND启用做好准备的保护效力 在此伙伴关系计划结束前进行研究。

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.