Porcine GM-CSF and APS as a novel complex immunostimulant improves the immune effect of pseudorabies inactivated vaccine

Abstract

Currently, pseudorabies (PR) is mainly controlled with attenuated and inactivated vaccines. In the case of inactivated vaccines, immunostimulants play a crucial role in triggering the host immune response. In this study, granulocyte-macrophage colony-stimulating factor (GM-CSF) and astragalus polysaccharide (APS) were investigated as a novel complex immunostimulant in inactivated PR vaccine. The findings indicated that neither porcine GM-CSF (pGM-CSF) nor APS exhibited any cytotoxic effect on cells. In addition, the PR vaccine+pGM-CSF+APS group exhibited higher levels of PRV-specific gB and neutralizing antibodies. Moreover, the group treated with pGM-CSF+APS immunostimulants demonstrated a notable increase in the production of IL-4, IL-10, IL-2, IFN-γ. After PRV challenge, the PR vaccine with pGM-CSF and APS alleviated clinical symptoms and reduced mortality. Additionally, the complex immunostimulant group showed a lower viral DNA copy number in various tissues compared to the PR vaccine alone group, as well as the groups treated with PR vaccine+pGM-CSF and PR vaccine+APS. Moreover, mice challenged with PRV in the PR Vaccine+pGM-CSF+APS group reduced substantial tissue lesions than other groups. These results demonstrate the potential of pGM-CSF and APS when used together as complex immunostimulant to enhance both humoral and cellular immune responses to inactivated vaccines, providing novel perspectives for the further development of immunostimulants.