Bacillus subtilis spores expressing SARS-CoV-2 Spike RBD

**Bacillus subtilis spores expressing SARS-CoV-2 Spike RBD** is an engineered oral vaccine candidate utilizing generally recognized as safe (GRAS) Bacillus subtilis spores as a delivery vehicle for the receptor binding domain (RBD) of the SARS-CoV-2 spike protein, displayed on the spore surface via fusion with spore coat proteins such as CotC, CotZ, or CotY. The spores resist gastrointestinal harsh conditions, enabling mucosal immunization that induces neutralizing antibodies (IgG and IgA) against SARS-CoV-2 RBD without entering the bloodstream, thus avoiding risks like blood coagulation associated with viral vectors. Preclinical mouse studies and a human pilot trial (n=6 healthy unvaccinated adults) demonstrated safety with no adverse events after multiple oral doses (e.g., 1×10^9 or 5×10^7 spores/kg), alongside significant immunogenicity including boosted proinflammatory cytokines (TNF-α, IL-1β, IL-6, IL-10) via adjuvant effects from B. subtilis peptidoglycan.[1][2][3]

Other names

Bacillus subtilis sporeB. subtilis spores displaying RBDrecombinant B. subtilis spores expressing sRBD