A multi-valent modified mRNA-LNP vaccine protects against Clostridioides difficile infection

Clostridioides difficile infection (CDI) is an urgent public health threat with limited therapeutic options. Toxoid-based vaccines have shown promise in limiting disease severity but have failed to reach primary endpoints in clinical trials. In this work, we developed nucleoside-modified messenger RNA (mRNA)-lipid nanoparticle vaccines based on C. difficile virulence factors, TcdA, TcdB, and Pro-Pro endopeptidase-1. This multivalent vaccine elicited robust antigen-specific humoral and cellular immune responses and high neutralizing antibody titers against C. difficile toxins. Vaccination protected mice from lethal CDI, and inclusion of non-toxin virulence factors as mRNA targets showed improved decolonization of toxigenic C. difficile from the gastrointestinal tract. C. difficile mRNA-LNP vaccines also did not induce changes to the intestinal microbiota. Our studies demonstrate mRNA-LNP vaccine technology as a platform for the development of novel C. difficile therapeutics.