The SARS-CoV-2 causes the novel coronavirus infectious disease 2019 (COVID-19). The binding of the viral spike protein to a receptor protein (called the angiotensin converting enzyme 2, or ACE2) is the first step in the infection of the human host cell. Blocking or inhibiting this interaction could stop the invasion of the human cell by this highly infectious virus. With this award, the Chemistry of Life Processes program is supporting the research of Dr. Xiaohong Tan at Bowling Green University in Bowling Green, Ohio to create DNA aptamers to inhibit this initial step of viral invasion. Aptamers are short sequences of DNA that fold into a shape that matches that of a target molecule, thereby keeping other molecules from binding. These DNA aptamers are “designed†by successive selection of molecules from large mixtures of different sequences, resulting in a few sequences that keep all other DNAs from binding the target. Dr. Tan uses this selection process to find DNA aptamers that bind tightly to the SARS-CoV-2 spike protein. Two of more of the identified DNA aptamers are linked together to create “super binders†that are much better at inhibiting the interaction than would any single aptamer. Constructing DNA aptamers that block the invasion of SARS-CoV-2 into human cells may lead to the design of antiviral agents that help lessen the infectivity that causes the COVID-19 pandemic. Educational and training activities will focus on postdoctoral researchers learning cutting edge techniques in chemical biology on a “front line†research problem. The team is developing ways to communicate their science to the public, to K-12 institutions, and to other research groups using distance learning technologies.
The goal of this project is to develop polymeric molecules (fusion DNA aptamers) that significantly interact with the binding domain of SARS-CoV-2. The objective is to effectively block the virus from binding to the specific ACE2 receptor, thereby blocking the entry of the virus into human cells and, as a result, its ability to cause COVID-19 infections. Professor Tan uses SELEX (systematic evolution of ligands by exponential enrichment) to identify individual aptamers that interact with three distinct regions on the cell binding domain of the spike (S) protein of SARS-CoV-2. The affinities of aptamers to their targets are measured through standard binding assays. These individual high affinity DNA aptamers are connected together using nucleic acid or chemical linkers to make fusion aptamers that have affinities comparable to those of antibodies. The ability of these fused DNA aptamer “super binders†to effectively block this interaction is tested against a recombinant SARS-CoV-2 spike protein using standard technologies, as well as live SARS-CoV-2 through collaboration with the University of Toledo Medical School.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
