Single self-cleaving mRNA vaccine expressing multiple viral structural proteins elicits robust immune responses and protects nursing piglets against PDCoV infection

Abstract

In this study, we designed and developed a novel mRNA vaccine, SMN-mRNA–LNP, capable of expressing the three major structural proteins (S, M, and N) of PDCoV from a single mRNA. This vaccine conferred superior active immune protection on piglets to that conferred by S2P-mRNA–LNP expressing only the S protein. Furthermore, following the immunization of pregnant sows with SMN-mRNA–LNP, their colostrum showed remarkably high IgA antibody titers reaching 1∶10 5.4 , representing a 25-fold increase over that in the inactivated vaccine group. By suckling, newborn piglets acquired significantly greater passive immunity, which ultimately conferred complete protection against PDCoV challenge.