Novel EG95-based mRNA vaccines induce long-term protective immunity against echinococcosis.

Cystic echinococcosis (CE), a neglected zoonotic disease caused by Echinococcus granulosus sensu lato, remains a significant public health and veterinary concern worldwide. Despite efforts to develop recombinant protein-based vaccines against EG95, a key protective antigen, existing platforms suffer from limited immunogenicity, short-lived immunity, and complex production processes. Here, we designed and evaluated three novel mRNA-LNP vaccines, including EG95 mRNA-LNP vaccine, IL-4-EG95 mRNA-LNP vaccine encoding EG95 fused with IL-4 via a flexible linker to enhance immune stimulation, and EG95-EC95 mRNA-LNP vaccine that multivalent formulation incorporating EC95 antigens from Echinococcus canadensis. The vaccine candidates were efficiently encapsulated in lipid nanoparticles and demonstrated robust target expression in vitro and in vivo. Immunization induced significantly stronger, more durable humoral and cellular immune responses compared to a commercial EG95 subunit vaccine both in mice and lambs. Notably, high levels of specific antibodies persisted for over 12 months post-vaccination. Parasites infection challenge experiments confirmed that these three mRNA-LNP vaccines, especially the IL-4-EG95 vaccine conferred superior protection, inhibited protoscolex survival and cyst growth. These results highlight the advantages of mRNA-based vaccines in safety, scalability, and flexibility over conventional approaches, offering a promising strategy for controlling E. granulosus sensu lato transmission and reducing the zoonotic burden of CE.