Shielding Replicating Single-cycle Vaccines against SARS-CoV-2

屏蔽针对 SARS-CoV-2 的复制单周期疫苗

• 批准号: 10884592
• 负责人: Michael A Barry
• 金额: $ 47.06万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-17 至 2024-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10884592
• 关键词: 2019-nCoV; Adenovirus Infections; Adenoviruses; Affect; Affinity; Animal Model; Animals; Antibodies; Antigens; Benchmarking; Binding; Biology; Blood; Blood Coagulation Factor; Blood Proteins; Blood coagulation; Body Weight; COVID-19; COVID-19 vaccination; COVID-19 vaccine; Cells; Chemical Engineering; Chemicals; Complementarity Determining Regions; Complex; Cryoelectron Microscopy; DNA; DNA biosynthesis; Dose; Engineering; Future; Genes; Genetic; Genetic Engineering; Hamsters; Human; Immune response; Immunization; Lung; Messenger RNA; Production; Proteins; RNA vaccine; Resolution; Risk; Safety; Serotyping; Structure; Testing; Thrombocytopenia; Transgenes; Translating; Vaccination; Vaccine Antigen; Vaccines; Viral Load result; Virion; Virus; gene therapy; in vivo; neutralizing antibody; oncolytic adenovirus; pathogen; permissiveness; preservation; prevent; risk mitigation; side effect; thrombotic; vaccine delivery; vaccine efficacy; vaccine safety; vaccine trial; vector

Abstract Many COVID-19 vaccines are replication-defective mRNA, DNA, or adenovirus (Ad) vaccines. In each case, the vaccine delivers its one copy of an antigen gene and expresses "1X" of the antigens that are encoded by the vaccine. We developed single cycle Ad (SC-Ad) vaccines that replicate vaccine antigen genes up to 10,000-fold in every cell to amplify antigen production but do not produce infectious progeny viruses. When RD-Ad and SC- Ad6 expressing SARS-CoV-2 are compared, SC-Ad produces 100 times more spike protein than RD-Ad and significantly higher spike antibodies than RD-Ad-Spike. When the animals were challenged 10.5 months after single immunization, SC-Ad reduced SARS-CoV-2 lung viral loads and damage and preserved body weights better than RD-Ad. However, observations of vaccine-induced thrombotic thrombocytopenia (VITT) in Ad26 and ChAdOx-1 COVID-19 vaccine trials endanger the prospects of SC-Ad and all other adenovirus vaccines. In one hypothesis, VITT is thought to be caused by the binding of PF4 to the hexons of Ad26 and ChAdOx-1. This complex is thought to provoke antibodies against PF4 that cause VITT. While VITT could theoretically occur with any adenovirus, the particular serotype of each Ad may influence the risk of this side effect. Different Ad serotypes vary in the hypervariable regions (HVRs) of their hexon proteins. These HVRs determine whether the antibodies and other proteins like PF4 bind or do not bind each adenovirus. We hypothesize that the natural binding of blood proteins to species C Ads may naturally shield them from PF4 binding whereas other serotypes are at risk of PF4 binding. One can also genetically and chemically engineer Ads to proactively shield them from interactions with antibodies and PF4. We hypothesize that genetic and chemical shielding can be used to make safer SC-Ad and other Ads for vaccination against SARS-CoV-2 and other pathogens. This project will test these hypotheses in three Specific Aims. In the first, we will perform high resolution cryo- electron microscopy to examine the interactions of PF4 and other proteins on species C and species D adenoviruses. In the second aim, we will compare the utility of genetic and chemical shielding strategies to protect Ads from PF4 and also against neutralizing antibodies. In the third aim, we will test if different Ad serotypes bound to PF4 can provoke VITT in animal models, whether this is different for different serotypes, and whether genetic and chemical shielding can maintain vaccine efficacy while mitigating the risks of VITT induction. Successful pursuit of this project will lead to better understanding of natural binding of blood clotting factors to different serotypes and how this affects their in vivo biology and side effects. This project will also test and optimize proactive strategy to increase adenovirus vaccine safety for SARS-CoV-2 and future pathogen targets. This can have utility for vaccines, gene therapy, or oncolytic adenoviruses to increase efficacy and safety and protect them from not only PF4, but also against problematic vector neutralizing antibodies.

摘要 许多COVID-19疫苗是复制缺陷型mRNA、DNA或腺病毒（Ad）疫苗。每例病患的 疫苗递送其抗原基因的一个拷贝，并表达由抗原基因编码的抗原的“1X”。 疫苗我们开发了单循环Ad（SC-Ad）疫苗，可将疫苗抗原基因复制高达10，000倍 在每个细胞中扩增抗原产生，但不产生感染性子代病毒。当RD-Ad和SC- 比较表达SARS-CoV-2的Ad 6，SC-Ad产生的刺突蛋白是RD-Ad的100倍， 显著高于RD-Ad-Spike的刺突抗体。当动物在10.5个月后被激发时， 单次免疫，SC-Ad减少了SARS-CoV-2肺部病毒载量和损伤并保留了体重 比RD-AD更好。然而，在Ad 26和Ad 28中观察到疫苗诱导的血栓性血小板减少症（VITT）， ChAdOx-1 COVID-19疫苗试验危及SC-Ad和所有其他腺病毒疫苗的前景。在一个 假设，VITT被认为是由PF 4与Ad 26和ChAdOx-1的六邻体结合引起的。这 复合物被认为可以激发抗PF 4的抗体，导致VITT。虽然理论上可能会发生VITT， 任何腺病毒，每种Ad的特定血清型可能会影响这种副作用的风险。不同的广告 血清型在其六邻体蛋白的高变区（HVR）中有所不同。这些HVR决定了 抗体和其他蛋白质（如PF 4）结合或不结合每种腺病毒。我们假设自然的 血蛋白与C种Ad的结合可以自然地保护它们免受PF 4结合，而其它血清型 有PF 4结合的风险。人们还可以通过基因和化学工程来主动屏蔽广告， 与抗体和PF 4的相互作用。我们假设基因和化学屏蔽可以用来 更安全的SC-Ad和其他Ad用于针对SARS-CoV-2和其他病原体的疫苗接种。 本项目将在三个具体目标中检验这些假设。首先，我们将进行高分辨率的冷冻- 电子显微镜检查PF 4和其他蛋白质对物种C和物种D的相互作用 腺病毒。在第二个目标中，我们将比较遗传和化学屏蔽策略的效用， 保护Ads免受PF 4的侵害，也保护Ads免受中和抗体的侵害。在第三个目标中，我们将测试是否不同的广告 与PF 4结合的血清型可以在动物模型中引起VITT，无论这对于不同血清型是否不同，以及 遗传和化学屏蔽是否可以保持疫苗效力，同时减轻VITT诱导的风险。 该项目的成功实施将使我们更好地了解凝血因子的天然结合， 不同的血清型以及这如何影响它们的体内生物学和副作用。该项目还将测试和 优化主动策略，提高腺病毒疫苗对SARS-CoV-2和未来病原体靶点的安全性。 这可用于疫苗、基因治疗或溶瘤腺病毒，以增加功效和安全性， 不仅保护它们免受PF 4的侵害，还保护它们免受有问题的载体中和抗体的侵害。