A muco-penetrating biomaterial-based subunit vaccine for programming protective immune responses to SARS-CoV-2

1.摘要/总结 鉴于SARS-CoV-2的进入部位是呼吸道粘膜，有效的SARS-CoV-2疫苗应 启动体液和呼吸道粘膜免疫应答。虽然鼻内亚单位疫苗将是一种 SARS-CoV-2的理想平台，跨鼻粘膜运输和缺乏安全有效的粘膜疫苗 佐剂阻碍了临床上可行的鼻内亚单位疫苗的开发。我们建议开发一种鼻内 由SARS-CoV-2蛋白与免疫刺激生物材料结合组成的疫苗， 鼻粘膜的运输屏障，从而诱导保护性粘膜和全身免疫。我们的平台是 由SARS-CoV-2受体结合域部分（RBD）与水溶性聚合物结合组成，称为 MPGAP，由结合鼻粘液的单体合成，破坏大腿内皮连接，并靶向和 活化抗原呈递细胞（APC）。因此，当鼻内施用时，RBD- MPGAP缀合物应当（1） 粘附于鼻粘液，增加在鼻上皮的停留时间，（2）拆除紧密连接，最大化 细胞旁转运到下面的APC和鼻相关淋巴组织，（3）靶向缀合的RBD并激活 APC，引发APC衍生的信号，激活T和B细胞。通过克服鼻腔的生物屏障 RBD-MPGAP通过增强内皮细胞的功能和靶向免疫刺激因子对免疫细胞的作用， 以及在没有脱靶效应的情况下的全身免疫。RBD-MPGAP缀合物将被生产、表征，并且 它们结合鼻粘液、增强细胞旁转运以及靶向和活化抗原呈递细胞的能力将被 在老鼠身上测试。RBD-MPGAP免疫小鼠的血清和呼吸道液的中和抗体滴度， 通过体外SARS-CoV-2中和试验进行评估。最后，对该材料的保护功效和耐久性进行了研究。 将在SARS-CoV-2小鼠模型中研究鼻内RBD-MPGAP引起的粘膜和全身免疫。 该项目的完成将验证鼻内SARS-CoV-2亚单位疫苗的临床前有效性， 一个可以对抗从季节性流感到下一个呼吸道病毒的许多其他呼吸道感染的平台 流行病

1. ABSTRACT/SUMMARY Given that the site of entry of SARS-CoV-2 is the respiratory mucosa, an effective vaccine for SARS-CoV-2 should initiate both humoral and respiratory mucosal immune responses. Although an intranasal subunit vaccine would be an ideal platform for SARS-CoV-2, transport across the nasal mucosa and a lack of safe and effective mucosal vaccine adjuvants thwart the development of a clinically-viable intranasal subunit vaccine. We propose to develop an intranasal vaccine composed of SARS-CoV-2 proteins conjugated to an immunostimulatory biomaterial that overcomes the transport barriers of the nasal mucosa and thus induces protective mucosal and systemic immunity. Our platform is composed of SARS-CoV-2 receptor-binding domain portion (RBD) conjugated to water-soluble polymers, termed MPGAP, that are synthesized from monomers that bind nasal mucus, disrupt endothelial thigh junctions, and target and activate antigen presenting cells (APCs). Thus, when administered intranasally, RBD- MPGAP conjugates should (1) adhere to nasal mucus, increasing residency time at the nasal epithelium, (2) dismantle tight junctions, maximizing paracellular transport to underlying APCs and nasal associated lymphoid tissue, (3) target conjugated RBD to and activate APCs, eliciting APC-derived signals that activate T and B cells. By overcoming the biological barriers of the nasal endothelium and targeting immunostimulatory factors to immune cells, RBD- MPGAP should induce protective mucosal and systemic immunity in the absence of off-target effects. RBD-MPGAP conjugates will be produced, characterized, and their ability to bind nasal mucus, enhance paracellular transport, and target and activate antigen presenting cells will be tested in mice. The neutralizing antibody titer of serum and respiratory fluids from RBD-MPGAP-immunized mice will be assessed via an in-vitro SARS-CoV-2 neutralization assay. Finally, the protective efficacy and durability of the mucosal and systemic immunity elicited by internasal RBD-MPGAP will be investigated in a SARS-CoV-2 mouse model. Completion of this project will validate the preclinical efficacy of an intranasal SARS-CoV-2 subunit vaccine and deliver a platform that could combat numerous other respiratory infections, from seasonal influenza to the next respiratory viral pandemic.