Astragalus polysaccharide enhances immunity and inhibits H9N2 avian influenza virus in vitro and in vivo

Abstract This study investigated the humoral immunization of Astragalus polysaccharide (APS) against H9N2 avian influenza virus (H9N2 AIV) infection in chickens. The effects of APS treatment on H9N2 infection was evaluated by an MTT [3(4, 5-dimethylthiazol-2-yl)-2, 3-diphenyl tetrazolium bromide] assay and analysis of MHC and cytokine mRNA expression. The effect on lymphocyte and serum antibody titers in vivo was also investigated. IL-4, IL-6, IL-10, LITAF, IL-12 and antibody titers to H9N2 AIV were enhanced in the first week after APS treatment. The results indicated that APS treatment reduces H9N2 AIV replication and promotes early humoral immune responses in young chickens.