Bacillus subtilis is regarded as safe organism by The Food and Drug Administration and it is presented in most food sources. Preliminary experiments have shown that the genetically engineered Bacillus subtilis can express and display receptor binding domain of spike protein of the SARS-COV2 on its spore coat, thus successfully induce the secretion of cytokines of human cells in vitro. Previous experiments also successfully demonstrated that a increased detection of neutralizing IgG and igM levels in mice after oral administrated with the Bacillus subtilis. This suggests that the transgenic spores of Bacillus subtilis have successfully activated the immune system, producing high-affinity neutralizing antibodies and memory B cells. Furthermore, no adverse effects were shown in all the mices. The engineered Bacillus subtilis will be further studied in a human trials through oral administration to test its safety and the immune effect resulted in human bodys.
