Highlights • CHO-expressed S1-Fc protein is very immunogenic in various animals and can rapidly induce strong antibody production. • S1-Fc protein solicits strong neutralizing activities against live virus. • Stable CHO cell line expressing 50 mg/L of S1-Fc, making it an accessible and affordable option for worldwide vaccination. The COVID-19 outbreak has become a global pandemic responsible for over 2,000,000 confirmed cases and over 126,000 deaths worldwide. In this study, we examined the immunogenicity of CHO-expressed recombinant SARS-CoV-2 S1-Fc fusion protein in mice, rabbits, and monkeys as a potential candidate for a COVID-19 vaccine. We demonstrate that the S1-Fc fusion protein is extremely immunogenic, as evidenced by strong antibody titers observed by day 7. Strong virus neutralizing activity was observed on day 14 in rabbits immunized with the S1-Fc fusion protein using a pseudovirus neutralization assay. Most importantly, in <20 days and three injections of the S1-Fc fusion protein, two monkeys developed higher virus neutralizing titers than a recovered COVID-19 patient in a live SARS-CoV-2 infection assay. Our data strongly suggests that the CHO-expressed SARS-CoV-2 S1-Fc recombinant protein could be a strong candidate for vaccine development against COVID-19.
【저자키워드】 COVID-19, SARS-CoV-2, Vaccine, Spike protein, 【초록키워드】 Vaccine development, COVID-19 vaccine, vaccination, Infection, virus, global pandemic, Protein, Neutralizing activity, COVID-19 outbreak, mice, Antibody titer, death, fusion protein, Live virus, Pseudovirus neutralization assay, COVID-19 patient, antibody production, confirmed case, injection, live SARS-CoV-2, immunogenic, MOST, immunized, STABLE, responsible, examined, induce, expressing, evidenced, Strong, CHO cell, virus neutralizing titer, 【제목키워드】 fusion protein, SARS-CoV-2 spike, recombinant, neutralizing response,