Selection, Design and Immunogenicity Studies of ASFV Antigens for Subunit mRNA Cocktail Vaccines with Specific Immune Response Profiles

The outbreaks African swine fever (ASF) in Eurasia have caused tremendous economic losses and the incursion to US would be disastrous to swine industry. Safe and effective vaccines have not been developed so far. Here, we report a novel ASFV mRNA vaccine designed with multiple rationalities to induce robust humoral and cellular immunities. Candidate vaccine antigens are selected by referring to homologs of protective antigens from the closely related vaccinia virus, known antigens eliciting strong host immune response, and viral capsid engineering for membrane-anchoring for optimal B cell engagement. To specifically induce strong T cell response, a T cell-directed vaccine antigen is designed by fusing multiple T cell epitopes (MTE) that are experimentally determined previously or predicted MHC-I high binders. Candidate antigens are formulated into lipid nanoparticle (LNP)- mRNA and further immunogenicity assessment in both mice and pigs reveals that different antigens elicits very distinct immune profiles including total antibody response, antibody effector functionality, and T cell response. Notably, the T cell-directed antigen induced robust cellular immunity. Furthermore, we demonstrated that multiple candidate cocktail vaccines based on distinct antigen immune profiles induced robust B cell and T cell immunities. Overall, The novel-designed vaccines coupled with mRNA technology shed light for an effective vaccine development against ASFV and strategies reported here can be utilized for developing vaccines against other large complex DNA viruses, such as monkeypox virus.