COVID-19 Variant Supplement - Expression and Purification of COVID19 Virus Spike (S) Protein for Diagnostics and Vaccines

Projects described within this rapid response proposal relate to diagnostics and vaccine production. The reagents generated also have longer term ramifications for studying virus attachment and developing inhibitors that block host cell entry and virus mediated fusion. The work in this proposal focuses on the spike protein (S) of the coronavirus which mediates attachment and entry into the host cell and is the major target of neutralizing antibodies that block infections. The first goal of this proposal is to generate large quantities of the S protein is a mammalian expression system that can be easily scaled up for large scale production. The protein generated in this procedure can be used to produce immune diagnostic kits as well as serve as a component of subunit vaccines or booster shots directed against COVID-19. The second aim describes the generation of recombinant vesicular stomatitis (VSV) viruses that express the Spike (S) protein derived from COVID-19 virus. In the first experiments, VSV genome vector is modified to contain coronavirus S protein in place of its G glycoprotein which normally mediates attachment and entry of the host cell. The S protein changes the tropism of the recombinant virus and provides a new antigen target for the immune system. VSV is highly attenuated in human cells and is tightly controlled by the host antiviral interferon system. It is also the vaccine vector for the highly effective Ebola virus vaccine. The diagnostic and vaccine reagents developed in this proposal will be distributed and tested by colleagues at the Canadian Center of Vaccinology (Halifax) and VIDO-InterVac Vaccine Cenre in Saskatoon. The final aim of this proposal will use the reagents generated in the proposal to study cell receptors for COVID19 coronavirus and study infections in susceptible cells using model viruses of lower risk and pathogenicity.