Chimeric ACE2 peptide ligand for diagnostic assays of SARS-CoV-2

最近，血管紧张素转换酶2（ACE 2）被证明是SARS-CoV-2的功能性受体，使病毒能够进入宿主靶细胞。利用基于结构的合理设计，我们设计了一种嵌合ACE 2肽，用作SARS-CoV-2分析定量的配体。我们的目的是改善初始设计，并检查嵌合肽的潜在用途，该嵌合肽显示由冠状病毒刺突蛋白S1的RBD识别的ACE 2的结合表面的3-D不连续表位代表。该嵌合体最初是基于S1 RBD和ACE 2复合物的多种结构（PDB编码6LZG、6VSB、6VXX、6VYB和6LXT）设计的。嵌合体在这方面的功能可以通过使用重组S1蛋白片段（S1胞外域和S1 RBD）和ACE 2蛋白的重组胞外域的体外竞争测定来容易地证明。我们将使用标记的蛋白质，可以固定使用BLI的结合特性。这项工作的目的是使嵌合ACE 2肽适应两种诊断应用：1）开发和表征用于检测唾液和粘膜样品中SARS-CoV-2的免疫-qPCR测定2）进行体内生物成像，生物分布，清除和毒性研究。新的应用代表了推进冠状病毒流行病学，致病性和受体相关知识的有前途的工具。

Recently, angiotensin-converting enzyme 2 (ACE2) was shown to be a functional receptor for SARS-CoV-2, enabling the virus to enter host target cells. Using structure-based rational design, a chimeric ACE2 peptide was designed by us for use as a ligand for analytical quantitation of SARS-CoV-2. We aim to improve the initial design and examine the potential uses of a chimeric peptide displaying a 3-D discontinuous epitope representative of the binding surface of ACE2 recognized by the RBD of the corona virus spike protein, S1. This chimera was initially designed based on multiple structures of the S1 RBD and ACE2 complexes (PDB codes 6LZG, 6VSB, 6VXX, 6VYB, and 6LXT).The chimera was meant to be a physiologically relevant, high affinity probe specific for the epitope that is critically important for the virus binding to the target cell surface receptor. Functionality of the chimera in that respect can be easily proven by in vitro competition assays using recombinant S1 protein fragments (S1 ectodomain and S1 RBD) and recombinant ectodomain of the ACE2 protein. We will use tagged proteins that can be immobilized to use BLI for characterization of binding. The aim of this work is to adapt the chimeric ACE2 peptide for two diagnostic applications: 1) to develop and characterize an imuno-qPCR assay for the detection of SARS-CoV-2 in saliva and mucosal samples 2) to perform in vivo bioimaging, biodistribution, clearance and toxicity studies. The novel applications represent promising tools to advance coronavirus epidemiology, pathogenicity, and receptors related knowledge.