Construction and expression of multi-stage antigen fusion protein RPC4 vaccine for Mycobacterium tuberculosis and its immunogenicity analysis in combination with adjuvant DIMQ.

Mycobacterium tuberculosis (M. tb) serves as the main pathogen responsible for Tuberculosis (TB). It predominantly targets the lungs and leads to a persistent infectious disease. The spread of drug-resistant tuberculosis and the exacerbation of economic burdens due to co-infections with Human Immunodeficiency Virus (HIV)/M. tb pose significant challenges in prevention and treatment. The BCG vaccine is currently the only approved (TB) vaccine, but its protective effect is limited for adults. In this research, we engineered the fusion protein gene RPC4, incorporating four crucial antigens from M. tb. The study revealed that the IFN-γ levels in the peripheral blood of infected patients significantly surpassed those in healthy individuals. To assess the immune response of RPC4 as a BCG-enhanced vaccine following initial immunity, researchers administered it alongside the novel adjuvant DIMQ to immunize mice. Experiments revealed that the BCG + RPC4/DIMQ vaccine induces a substantial immunogenic response in the mice.