Incorporation of Escherichia coli heat-labile enterotoxin B subunit into rabies virus particles enhances its immunogenicity in mice and dogs

Although inactivated vaccines against rabies have the advantage of high safety, effective protection against rabies virus (RABV) infection often requires multiple, high-dose immunization. Incorporating a molecular adjuvant into the viral particles has been found to be a useful strategy to promote the immune effectiveness of inactivated vaccines. In this study, we constructed a recombinant virus, rCVS11-LTB, which chimerically expresses a molecular adjuvant heat-labile enterotoxin B subunit (LTB) protein on the surface of the RABV particles. Immunogenicity in vivo was found to be promoted by rCVS11-LTB through the activation of dendritic cells (DCs). Our results demonstrated that inactivated rCVS11-LTB was able to induce higher levels of virus-neutralizing antibodies (VNAs) in both mice and dogs than the parent virus rCVS11, to enhance the cellular immune response and T cell immune memory in mice, and was also able to provide 100% protection in mice from lethal doses of rabies virus, indicating its potential as a safe and effective inactivated rabies vaccine candidate.