Ginsenoside Re as an adjuvant to enhance the immune response to the inactivated rabies virus vaccine in mice

The inactivated rabies virus vaccine (RV) is a relatively expensive vaccine, prone to failure in some cases. Ginsenoside Re (Re) is a saponin isolated from Panax ginseng, and has an adjuvant property. Here the adjuvant effect of Re to improve the immune response to the RV is evaluated in mice. ICR mice were immunized with saline, 2.50 mg/kg Re, 20 mu l RV, 100 mu l RV, or 20 mu l of RV adjuvanted with Re (1.25, 2.50 or 5.00 mg/kg). Different time points after boosting, we measured serum antibodies in blood samples and separated splenocytes to detect lymphocyte proliferation and the production of IL-4, IL-10, IL-12, and IFN-gamma in vitro. We also compared immunizations containing 20 mu l RV and 20 mu l RV adjuvanted with Re (5.00 mg/kg) for the expression of CD4(+) and CDS+ T-cell subsets at different time points. Results indicated that co-administration of Re significantly enhanced serum antibody titers, increased the CD4(+):CD8(+) ratio, and enhanced both proliferation responses and IL-4, IL-10, IL-12 and IFN-gamma secretions. Both Thl and Th2 immune responses were activated. The supplementation of the Re (5.00 mg/kg) to 20 mu l of RV significantly amplified serum antibody responses and Thl/Th2 responses inducing similar protection as did 100 mu l of RV. This suggests that Re could be used to reduce the dose, and therefore the cost, of the RV to achieve the same effective protection. Re merits further studies for use with vaccines of mixed Thl/Th2 immune responses. (C) 2014 Elsevier B.V. All rights reserved.