Increased humoral immune responses of pigs to foot-and-mouth disease vaccine supplemented with ginseng stem and leaf saponins.

Vaccination is a conventional approach against foot-and-mouth disease (FMD) in pigs. However, failure to elicit an immune response to vaccine has been reported. Our previous investigation showed that ginseng stem and leaf saponins (GSLS) and mineral oil acted synergistically to promote Th1/Th2 immune responses to FMD vaccine in mice. This study was designed to i) find the optimal doses of GSLS in oil-emulsified FMD vaccines to induce immune responses in mice and pigs and ii) to evaluate the effect of oil-emulsified FMD vaccine supplemented with GSLS on the immune responses in pigs, by measuring the serum indirect hemagglutination (IHA) titer and IgG and IgG subclass levels. The GSLS-enhanced immune response to FMD oil-emulsion vaccine depended on the dose of GSLS added to the vaccine. Addition of GSLS at a dose of 40 μg to 2 ml of FMD oil-emulsified vaccine significantly enhanced the humoral immune responses in pigs, when compared to the vaccine without GSLS (P<0.05). The increased antibodies included IgG1 and IgG2. Hence, GSLS and oil adjuvant synergistically promoted the immune responses to vaccination against FMD in pigs, and GSLS could be a promising vaccine additive to improve oil-emulsified veterinary vaccines.