PDF(Pubmed)
Abstract：
There is a continued need for sarbecovirus vaccines that can be manufactured and distributed in low- and middle-income countries (LMICs). Subunit protein vaccines are manufactured at large scales at low costs, have less stringent temperature requirements for distribution in LMICs, and several candidates have shown protection against SARS-CoV-2. We previously reported an engineered variant of the SARS-CoV-2 Spike protein receptor binding domain antigen (RBD-L452K-F490W; RBD-J) with enhanced manufacturability and immunogenicity compared to the ancestral RBD. Here, we report a second-generation engineered RBD antigen (RBD-J6) with two additional mutations to a hydrophobic cryptic epitope in the RBD core, S383D and L518D, that further improved expression titers and biophysical stability. RBD-J6 retained binding affinity to human convalescent sera and to all tested neutralizing antibodies except antibodies that target the class IV epitope on the RBD core. K18-hACE2 transgenic mice immunized with three doses of a Beta variant of RBD-J6 displayed on a virus-like particle (VLP) generated neutralizing antibodies (nAb) to nine SARS-CoV-2 variants of concern at similar levels as two doses of Comirnaty. The vaccinated mice were also protected from challenge with Alpha or Beta SARS-CoV-2. This engineered antigen could be useful for modular RBD-based subunit vaccines to enhance manufacturability and global access, or for further development of variant-specific or broadly acting booster vaccines.
摘要：
仍然需要能够在低收入和中等收入国家（LMICs）生产和销售的肉瘤病毒疫苗。亚单位蛋白疫苗以低成本大规模生产，在LMIC中分布的温度要求不那么严格，一些候选人已经显示出对SARS-CoV-2的保护作用。我们先前报道了SARS-CoV-2刺突蛋白受体结合域抗原（RBD-L452K-F490W；RBD-J）的工程化变体，与祖先RBD相比，具有增强的可制造性和免疫原性。这里,我们报告了第二代工程RBD抗原（RBD-J6），在RBD核心中的疏水性隐蔽表位具有两个额外的突变，S383D和L518D,这进一步提高了表达滴度和生物物理稳定性。RBD-J6保留对人恢复期血清和除靶向RBD核心上的IV类表位的抗体以外的所有测试的中和抗体的结合亲和力。用在病毒样颗粒（VLP）上展示的三种剂量的RBD-J6的Beta变体免疫的K18-hACE2转基因小鼠产生的中和抗体（nAb）与两种剂量的Comirnaty相似的9种SARS-CoV-2变体。还保护接种的小鼠免受α或βSARS-CoV-2的攻击。这种工程化抗原可用于基于RBD的模块化亚单位疫苗，以提高可制造性和全球可获得性，或进一步开发变体特异性或广泛作用的加强疫苗。
