Foot-and-mouth disease (FMD) is a highly contagious viral infection of cloven-hoofed livestock that causes substantial economic losses worldwide. Although chemically inactivated vaccines are effective, they are limited by biosafety concerns related to...
Foot-and-mouth disease (FMD) is a highly contagious viral infection of cloven-hoofed livestock that causes substantial economic losses worldwide. Although chemically inactivated vaccines are effective, they are limited by biosafety concerns related to live virus handling, the requirement for biosafety level 3 (BSL-3) facilities, manufacturing complexity, and lack of DIVA compatibility. To address these limitations, we evaluated a Venezuelan equine encephalitis virus (VEEV)–derived self-amplifying mRNA (saRNA) vaccine platform encoding FMDV antigens. In vitro analyses demonstrated that all three saRNA constructs supported efficient intracellular translation, expressed FMDV antigens, and sustained RNA replication, resulting in detectable RNA and protein expression for up to 120 hours. However, in mice, only the LPX-formulated capsid precursor (CP) saRNA induced FMDV-specific and neutralizing antibody responses comparable to those elicited by a commercial vaccine. Importantly, the efficacy of LPX-formulated CP saRNA was further demonstrated in swine, a primary target species for FMD vaccination. Following booster immunization, LPX-formulated CP saRNA induced humoral immune responses comparable to those of the commercial vaccine and, unlike the commercial vaccine, additionally elicited cellular immune responses. Following FMDV challenge, LPX-formulated CP saRNA provided robust clinical protection in swine, comparable to that of the commercial vaccine, and effectively suppressed viremia and viral shedding. Collectively, these findings demonstrate the potential of LPX-formulated CP saRNA as a promising next-generation vaccine candidate for the control of foot-and-mouth disease.