MMRRC COVID-19 variant testing in humanized mouse models

摘要和工作范围 加州大学戴维斯分校突变小鼠资源和研究中心(MMRRC-UC Davis) 很高兴提交此行政补充文件，提供长达一年的支持，以回应ORip的 参与PA-20-272，“对现有NIH补助金和合作协议的行政补充” 特别与严重急性呼吸综合征冠状病毒2型(新冠肺炎)有关。 本申请解决了支持新冠肺炎相关研究的呼叫的多个声明目标， 包括建立和表征新冠肺炎急性后遗症的动物模型，以及 研究现有新冠肺炎动物模型对新出现的病毒基因组变异的易感性。具体来说， 这个应用程序将生成多基因人源化小鼠模型，用于病毒挑战、验证和后期处理 新冠肺炎(PASC)对青年和老年小鼠的急性后遗症 在ABSL3环境中筛选平台。该项目将建立在我们成功努力的基础上，以产生 几个基因(ACE2、TMPRSS2和TMPRSS2)的单基因人源化敲除/小鼠敲除小鼠系 Furin)参与SARS-CoV-2的结合、进入和激活。有了这一先前的经验，我们现在 建议确定新的多基因人源化小鼠的传染性和传播性，以评估 它们可以用来作为人类PASC的合适模型。特别是在这个项目中，我们将在1)中使用 我们现有的单基因模型的体外受精(IVF)扩展和杂交快速产生 HACE2/hTMPRSS2和hACE2/hTMPRSS2/hFURIN多基因人源化小鼠模型，2)验证 目前占优势的循环(B.1.1.7；菌株： 美国/CA_CDC_5574/2020)在年轻和老年多基因人源化小鼠的雌雄队列中 3)建立人源化小鼠繁育群体和超低温保存种质 用于存档和分发给生物医学研究社区的模型。验证研究将涉及 术后病毒载量和清除、体重动力学和肺部炎症的系统特征 SARS-CoV-2对雄性和雌性小鼠队列的挑战；阳性结果将传达给 美国国立卫生研究院的主动临床前工作组和其他人。此外，观察性和病理学筛查 存活的衰老小鼠将被用于筛选PASC的证据；有希望的发现将是 与PASC倡议和调查员联盟(OTA-21-015A和B)成员进行沟通，并 NIH其他工作人员确保人体研究和动物功能研究结果的快速翻译 模特们。此外，我们将确保我们的鼠标型号和测试平台随时可用于 被其他研究人员用来快速评估不仅新出现的SARS-CoV-2在体内的后果 逃脱当前治疗和疫苗策略的变种，以及未来病毒的类似高- 影响大流行的可能性。这项研究对于克服小鼠和小鼠之间的遗传差异是必不可少的 并填补现有新冠肺炎小动物模型中阻碍研究翻译的关键空白 对改善人类健康的发现，包括了解发展、治疗和 PASC的预防、抗病毒治疗的有效性和疾病预防疫苗的可靠性 战略。

ABSTRACT & SCOPE OF WORK The Mutant Mouse Resource and Research Center at the University of California, Davis (MMRRC-UC Davis) is pleased to submit this administrative supplement for up to 1 year of support in response to ORIP’s participation in PA-20-272, “Administrative Supplements to Existing NIH Grants and Cooperative Agreements” specifically related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19). This application addresses a number of the stated objectives of the call to support COVID-19 related research, including to develop and characterize animal models for post-acute sequelae of COVID-19 (PASC) and to study the susceptibility of existing COVID-19 animal models to emerging viral genomic variants. Specifically, this application will generate polygenic humanized mouse models for virus challenge, validation, and post- acute sequellae of COVID-19 (PASC) in both young and aging mice using well-established testing and screening platforms in an ABSL3 environment. This project will build upon our successful efforts to generate monogenic humanized knockin/murine knockout mouse lines for several genes (ACE2, TMPRSS2, and FURIN) involved in SARS-CoV-2 binding, entry, and activation. With this prior experience in hand, we now propose to determine infectivity and transmission in new polygenic humanized mice to assess the extent to which they can be used as suitable models of PASC in humans. Specifically in this project we will 1) use in vitro fertilization (IVF) expansion and intercrossing of our extant monogenic models to rapidly generate polygenic humanized mouse models of hACE2/hTMPRSS2 and hACE2/hTMPRSS2/hFURIN, 2) validate the pathophysiological effects and assess PASC after challenge with currently dominant circulating (B.1.1.7; strain: USA/CA_CDC_5574/2020) in young and aging male and female cohorts of polygenic humanized mice under ABSL3 conditions, and 3) establish breeding colonies and cryopreserved germplasm of humanized mouse models for archiving and distribution to the biomedical research community. Validation studies will involve systematic characterization of viral load and clearance, body weight kinetics, and lung inflammation after SARS-CoV-2 challenge of male and female cohorts of mice; positive results will be communicated to the ACTIV-Preclinical Working Group and others at NIH. In addition, observational and pathological screening of surviving aging mice will be conducted to screen for evidence of PASC; promising findings will be communicated with members of the PASC Initiative and Investigator Consortium (OTA-21-015A and B) and other NIH staff to ensure rapid translation of findings for human studies and functional studies in animal models. Further, we will ensure that our mouse models and testing platform will be made readily available for use by other researchers to swiftly assess the in vivo consequences of not only newly appearing SARS-CoV-2 variants that escape current therapeutic and vaccine strategies but also of future viruses with similarly high- impact pandemic potential. This study is essential to overcome genetic discrepancies between mouse and human and to fill crucial gaps in existing small animal models of COVID-19 that hinder translation of research findings to improvements in human health, including understanding the development, treatment, and prevention of PASC, the effectiveness of antiviral therapies, and the reliability of disease-prevention vaccine strategies.