An immunoinformatics-guided multi-epitope vaccine targeting the WbkC protein confers protection against Brucella...

For brucellosis, a common zoonotic illness brought on by Brucella species, there is presently no licensed subunit vaccine. This study targeted the WbkC protein, a methyltransferase that participates in the biosynthesis of the O-antigen of Brucella lipopolysaccharide, which has been demonstrated to stimulate a vigorous immune response in mice. A new multi-epitope vaccine was created using immunoinformatics methods, and its protective efficacy was systematically evaluated.

Immunodominant linear B lymphocyte (LBL), cytotoxic T lymphocyte (CTL), and helper T lymphocyte (HTL) epitopes of WbkC were linked with short connectors to construct and name the protein rWbkC. Bioinformatics analysis showed high antigenicity with a predicted score of 1.24 (>0.4), favorable solubility, and no allergenicity/toxicity. Molecular docking/simulations confirmed stable rWbkC-TLR2/4 binding. Immune simulation revealed elevated IFN-γ, IL-2, and IgG/IgM levels. In vivo experiments showed that giving mice three shots of rWbkC caused much higher levels of IgG (P < 0.01) and IgG1 (P < 0.05) than those induced by WbkC. Protection was assessed by measuring bacterial clearance of B. melitensis M5 in immunized mice. Vaccination with both rWbkC and WbkC significantly reduced bacterial loads in the spleen (both P < 0.001) and liver (P < 0.001 for rWbkC, P < 0.05 for WbkC) compared with PBS. Notably, the rWbkC vaccine exhibited superior efficacy in clearing bacterial burden in the liver compared with WbkC (P < 0.01).

To summarize, the rWbkC multi-epitope vaccine, based on WbkC, demonstrates high immunogenicity and protective efficacy, offering a promising innovative strategy for brucellosis vaccine development.