A Trim-RBD-GEM vaccine candidate protects mice from SARS-CoV-2.

The SARS-CoV-2 pandemic has continued for about three years since emerging in late December 2019, resulting in millions of deaths. Therefore, there is an urgent need to develop a safe and effective vaccine to control SARS-CoV-2. In this study, we developed a bacterium-like particle vaccine that displays the SARS-CoV-2 receptor binding domain (RBD) (named Trim-RBD-GEM) using the GEM-PA system. We evaluated the immunogenicity and protective efficacy of the Trim-RBD-GEM vaccine with the oil-in-water adjuvant AddaVax in C57BL/6 N mice intramuscularly. We found that Trim-RBD-GEM&AddaVax induced high levels of humoral immunity in C57BL/6 N mice. Additionally, the lung virus loads in the immunized group were significantly decreased compared to the adjuvant control and mock groups. Therefore, this vaccine provides protection against lethal infection in a C57BL/6 N mouse model. Our Trim-RBD-GEM&AddaVax vaccine is potentially a promising, rapid, and safe subunit vaccine for preventing and controlling SARS-CoV-2. • A bacterium-like particle vaccine in the form of SARS-CoV-2 RBD protein trimer was constructed with a purity of over 97%. • The GEM-PA surface presentation system only requires one step of centrifugation to prepare pellet antigens. • Immunization of C57BL/6 N mice with AddaVax adjuvant induced high levels of ELISA and neutralizing antibodies. • Trim-RBD-GEM using AddaVax adjuvant provided lethal protection against C57BL/6 N after the SARS-CoV-2 challenge. [ABSTRACT FROM AUTHOR]