Scientific Abstract

African swine fever virus (ASFV) is spreading to many countries and regions, causing significant losses to swine producers. Currently, there are no commercial vaccines or treatments available for ASF. Although multiple live-attenuated virus (LAV) vaccines have been generated and demonstrated efficacy in inducing protection against parental virulent ASV strains, there is a significant concern about the use of LAV vaccines, especially the risk of reversion to virulence. The primary objective of this project was to assess the feasibility of utilizing the mRNA vaccine technology to develop a subunit vaccine against ASFV. Four well-characterized ASFV genes, namely p32, p54, C-type lectin, and CD2v were selected and mRNA transcripts of these selected ASFV genes were successfully generated. When transfected into HEK-293T cells using a commercial transfection reagent, two of these mRNA transcripts (p32 and p54) exhibited high levels of protein expression. Three different lipid nanoparticle formulations were developed to encapsulate the mRNA transcripts. However, none of these LNP formulations were effective in transfecting the mRNA transcripts into HEK-293T cells. Subsequently, when administered to mice, only one LNP formulation showed a modest induction of antibody responses. We believe that the inefficient transfection efficiency and low immunogenicity observed with the LNP-mRNA formulations in this study may be attributed to the specific lipid types and formulation methods employed. Therefore, further efforts are required to develop an effective LNP formulation for encapsulating and delivering mRNA to pigs.