The search for vaccines that protect from severe morbidity and mortality as a result of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19) is a race against the clock and the virus. Several vaccine candidates are currently being tested in the clinic. Inactivated virus and recombinant protein vaccines can be safe options but may require adjuvants to induce robust immune responses efficiently. In this work we describe the use of a novel amphiphilic imidazoquinoline (IMDQ-PEG-CHOL) TLR7/8 adjuvant, consisting of an imidazoquinoline conjugated to the chain end of a cholesterol-poly(ethylene glycol) macromolecular amphiphile). This amphiphile is water soluble and exhibits massive translocation to lymph nodes upon local administration, likely through binding to albumin. IMDQ-PEG-CHOL is used to induce a protective immune response against SARS-CoV-2 after single vaccination with trimeric recombinant SARS-CoV-2 spike protein in the BALB/c mouse model. Inclusion of amphiphilic IMDQ-PEG-CHOL in the SARS-CoV-2 spike vaccine formulation resulted in enhanced immune cell recruitment and activation in the draining lymph node. IMDQ-PEG-CHOL has a better safety profile compared to native soluble IMDQ as the former induces a more localized immune response upon local injection, preventing systemic inflammation. Moreover, IMDQ-PEG-CHOL adjuvanted vaccine induced enhanced ELISA and in vitro microneutralization titers, and a more balanced IgG2a/IgG1 response. To correlate vaccine responses with control of virus replication in vivo, vaccinated mice were challenged with SARS-CoV-2 virus after being sensitized by intranasal adenovirus-mediated expression of the human angiotensin converting enzyme 2 (ACE2) gene. Animals vaccinated with trimeric recombinant spike protein vaccine without adjuvant had lung virus titers comparable to non-vaccinated control mice, whereas animals vaccinated with IMDQ-PEG-CHOL-adjuvanted vaccine controlled viral replication and infectious viruses could not be recovered from their lungs at day 4 post infection. In order to test whether IMDQ-PEG-CHOL could also be used to adjuvant vaccines currently licensed for use in humans, proof of concept was also provided by using the same IMDQ-PEG-CHOL to adjuvant human quadrivalent inactivated influenza virus split vaccine, which resulted in enhanced hemagglutination inhibition titers and a more balanced IgG2a/IgG1 antibody response. Enhanced influenza vaccine responses correlated with better virus control when mice were given a lethal influenza virus challenge. Our results underscore the potential use of IMDQ-PEG-CHOL as an adjuvant to achieve protection after single immunization with recombinant protein and inactivated virus vaccines against respiratory viruses, such as SARS-CoV-2 and influenza viruses.

中文翻译：

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单次和修饰的咪唑并喹啉TLR7 / 8激动剂佐剂重组穗蛋白疫苗对小鼠SARS-CoV-2感染的消毒免疫。

寻找可预防因感染严重急性呼吸系统综合症冠状病毒2（SARS-CoV-2）而导致严重发病和死亡的疫苗，冠状病毒是2019年导致冠状病毒疾病的病毒（COVID-19），这是一场争分夺秒的竞赛。病毒。目前正在临床中测试几种候选疫苗。灭活的病毒和重组蛋白疫苗可能是安全的选择，但可能需要佐剂才能有效诱导强大的免疫反应。在这项工作中，我们描述了新型两亲咪唑喹啉（IMDQ-PEG-CHOL）TLR7 / 8佐剂的使用，该佐剂由与胆固醇-聚乙二醇大分子两亲链末端偶联的咪唑喹啉组成。该两亲物是水溶性的，并且在局部给药时表现出大量易位至淋巴结，可能通过与白蛋白结合。在BALB / c小鼠模型中，用三聚体重组SARS-CoV-2穗蛋白进行单次接种后，IMDQ-PEG-CHOL用于诱导针对SARS-CoV-2的保护性免疫应答。SARS-CoV-2穗状疫苗制剂中包含两亲性IMDQ-PEG-CHOL，导致免疫细胞募集和引流淋巴结激活增强。与天然可溶性IMDQ相比，IMDQ-PEG-CHOL具有更好的安全性，因为前者在局部注射后诱导更局部的免疫反应，从而防止了系统性炎症。此外，IMDQ-PEG-CHOL佐剂疫苗诱导增强的ELISA和体外微中和效价，以及更平衡的IgG2a / IgG1反应。为了将疫苗反应与体内病毒复制控制联系起来，鼻内腺病毒介导的人血管紧张素转化酶2（ACE2）基因的表达致敏后，接种疫苗的小鼠受到SARS-CoV-2病毒的攻击。不含佐剂的三聚体重组刺突蛋白疫苗接种的动物的肺病毒滴度与未接种的对照小鼠相当，而接种IMDQ-PEG-CHOL佐剂的疫苗控制病毒复制的动物在第4天无法从肺中恢复感染后。为了测试IMDQ-PEG-CHOL是否也可以用于目前许可用于人类的佐剂疫苗，还通过使用相同的IMDQ-PEG-CHOL佐剂人类四价灭活流感病毒裂解疫苗来提供概念验证，导致增强的血凝抑制效价和更平衡的IgG2a / IgG1抗体反应。当给小鼠致命的流感病毒攻击时，增强的流感疫苗反应与更好的病毒控制相关。我们的结果强调了将IMDQ-PEG-CHOL用作佐剂的潜在用途，可在重组蛋白和灭活病毒疫苗对呼吸道病毒（如SARS-CoV-2和流感病毒）进行单次免疫后获得保护。