The immune response to a recombinant Lactococcus lactis oral vaccine against foot-and-mouth disease virus in mice

Objective Development of an effective mucosal vaccine to induce specific immune responses against Foot-and-mouth disease virus (FMDV). Results For this purpose, the FMDV VP1 gene (SPVP1) was optimized and synthesized based on the codon bias of Lactococcus lactis ( L . lactis ), and then incorporated in the plasmid pNZ8148. L. lactis NZ9000 containing the pNZ8148-SPVP1 recombinant plasmid was used as an oral delivery vehicle to induce anti-FMDV mucosal and systemic immune responses in mice. After confirmation that the SPVP1 protein was expressed successfully in the recombinant L. latic , the mice were orally challenged with NZ9000-pNZ8148, NZ9000-pNZ8148-SPVP1, phosphate-buffered saline as a mock infection group, or with inactivated vaccine as a positive group. Mice immunized with NZ9000-pNZ8148-SPVP1 produced high levels of mucosal secretory IgA (sIgA), antigen-specific serum IgG, IgA, and neutralizing antibodies, and developed stronger cell-mediated immune reactions and significant T spleen lymphocyte proliferation. Furthermore, the recombinant group generated much higher levels of IFN-γ, IL-2, IL-4, IL-5, and IL-10 than the other groups. Conclusions Potent immune responses were successfully elicited in mice with FMDV VP1 delivered through L. lactis .