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

最近，血管紧张素转换酶2（ACE 2）被证明是一种功能性受体 SARS-CoV-2，使病毒能够进入宿主靶细胞。使用基于结构的rational 设计，我们设计了一个嵌合ACE 2肽，用作分析的配体， SARS-CoV-2的定量。我们的目标是改进最初的设计， 展示代表性的3-D不连续表位的嵌合肽的用途 冠状病毒刺突蛋白S1的RBD识别ACE 2的结合表面。这 嵌合体最初是基于S1 RBD和ACE 2复合物的多种结构设计的 (PDB编码6LZG、6VSB、6VXX、6VYB和6LXT）。 相关的，高亲和力的探针特异性的表位是至关重要的， 病毒与靶细胞表面受体结合。嵌合体的功能在于 这一点可以通过使用重组S1蛋白的体外竞争测定来容易地证明 片段（S1胞外域和S1 RBD）和ACE 2蛋白的重组胞外域。我们将 使用可固定化的标记蛋白质以使用BLI表征结合。的 这项工作的目的是使嵌合ACE 2肽适应两种诊断应用：1） 开发并表征用于检测唾液中SARS-CoV-2的免疫qPCR检测方法， 2）进行体内生物成像、生物分布、清除和毒性 问题研究这些新的应用代表了推进冠状病毒流行病学的有前途的工具， 致病性及受体相关知识。

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.