A Lipid Nanoparticle-Formulated GP5-mRNA Vaccine Induces PRRSV-Specific Humoral and Cellular Immune Responses in BALB/c Mice

Abstract

Simple Summary Porcine reproductive and respiratory syndrome virus (PRRSV) is an important pathogen that causes severe economic losses in the swine industry. Current vaccines are useful but often provide limited protection against genetic diversity or newly emerging PRRSV strains. Therefore, new vaccine strategies are still needed. In this study, we developed an mRNA vaccine candidate encoding the PRRSV GP5 protein, which is an important viral envelope protein involved in immune responses. The GP5-mRNA was encapsulated into lipid nanoparticles to improve delivery and was tested in BALB/c mice. The vaccine candidate successfully expressed GP5 protein in cells and induced a PRRSV-specific antibody response in mice. Sera from immunized mice also showed detectable neutralizing activity. Furthermore, vaccinated mice exhibited increased CD4+ and CD8+ T-cell responses, as well as higher levels of immune-related cytokine production after antigen stimulation. These findings suggest that the GP5 mRNA-LNP vaccine candidate can induce both humoral and cellular immune responses in mice. Because mice are not the natural host of PRRSV, further immunization and PRRSV challenge studies are needed to evaluate protective efficacy, viremia reduction, clinical protection, and pathological changes in pigs.