Ginseng and aluminium hydroxide act synergistically as vaccine adjuvants

Abstract

The dry extract prepared from the Panax ginseng C.A. Meyer-root (total ginseng (T-ginseng)) contain ginsenosides (G-des) which were shown to have adjuvant properties as demonstrated by: (a) injecting guinea pigs with a mixture of T-ginseng and inactivated porcine parvovirus (PPV) as a conventional vaccine; (b)injecting PPV-antigen and T-ginseng simultaneously but separately at different sites on the animal and (c)injecting only the T-ginseng 1 or 2 weeks prior to immunisation with the PPV-antigen. Using a haemagglutination inhibition (HI) test in the antibody titration, it was found that the mean HI-titre for the animals injected with PPV-antigen only was 320 +/- 0. By comparison, the mean titre value was 2026 +/- 1206 for the sera from the animals injected with the same vaccine but adjuvanted with 4 mg of T-ginseng, while the antibody titre induced by a vaccine containing Al(OH)(3)-gel was 2986 +/- 1596. Interestingly, the T-ginseng and Al(OH)(3) acted synergistically and further improved the antibody response to the PPV-antigen to 6826 +/- 2413, i.e. more than 20 times the HI titre of the non-adjuvanted PPV-vaccine. Immunisations using PPV-vaccines adjuvanted with single purified G-des demonstrated that the ginseng fractions Rb1 and Rg1 are potent adjuvants inducing higher or similar antibody titres than the vaccine adjuvanted with Al(OH)(3), e.g. Rb1 tested at a concentration of 830 microg per dose induced a significantly (P = 0.009) higher antibody titre than the one adjuvanted with Al(OH)(3). Nevertheless, different than the mixture Al(OH)(3)-T-ginseng; Rb1 and Rg1 act antagonistically and partially inhibit each other. The G-des adjuvanted vaccines induced significantly (P = 0.0011) higher titres of IgG2 antibodies compared with IgG1.