Immunogenicity of a recombinant vaccine against Lawsonia intracellularis in mice

Lawsonia intracellularis is the cause of proliferative enteropathy (PE), which is highly prevalent in swine, causing substantial economic losses to the sector. The available PE vaccines have protection-related limitations. Therefore, the objective of the present study was to evaluate the ability of L. intracellularis recombinant protein, fused with tetanus toxin T helper (TT-Th) carrier molecule, to stimulate a specific immune response in a mouse experimental model. rLiTT expression was performed in Escherichia coli BL21 Star™ (DE3) cells, evaluated by SDS-PAGE, and confirmed by Western blot using a monoclonal anti-His antibody, showing a band of 18 kDa size, also the rLiTT was recognized by sera from naturally infected pigs, vaccinated pigs, and rLiTT vaccinated mice, showing its antigenicity. Specific antibodies (IgG, IgM, and IgA) against rLiTT were detected after the prime vaccine dose in mice immunized with rLiTT adsorbed on aluminum hydroxide (rLiTT/AH). The upregulation of NFkB, IL4, IL12 , and IFN-y cytokine genes was evaluated in vaccinated mice splenocytes and peritoneal macrophages to assess the cell response. Thus, the experimental vaccine shows promising results to be tested in pigs.