Construction and evaluation of a novel bacillus subtilis spores-based enterovirus 71 vaccine

Enterovirus 71 (EV71) infection and its associated hand-foot-mouth disease is a significant public health problem. The purpose of this study is to develop a novel vaccine to prevent EV71 infection. Bacillus subtilis spores were engineered to express VP1 protein of EV71 with CotB as carrier protein. The recombination was tested in adult mice for the ability to induce immune responses. Mice were inoculated orally and intranasally simultaneously with the spores. The vaccine’s efficacy on stimulating immune responses was evaluated by measuring the titer of anti-VP1 IgG and IgA with enzyme-linked-immunosorbent serologic assay (ELISA), and the number of VP1-specific T cells by ELIS-POT. Serum titers of IgG (0.41±0.05 vs 0.20±0.07) and IgA (0.24±0.02 vs 0.11±0.01) in mice immunized with recombinant CotB-VP1 spores were higher than that of mice immunized with nonrecombinant spores 1A771. Splenocytes from the group of mice receiving VP1 spores vaccination contained 1.69±0.52/104 VP1-specific T cells, which was greater than the 0.06±0.06/104 cells from the group of mice receiving nonrecombinant spores vaccination. In conclusion, B. subtilis spores displaying VP1 of EV71 are effective in stimulating cellular immunity and humoral immunity in mice.