Adjuvant Effect of Ginsenosides on the Recombinant SO7 Antigen Against Eimeria tenella in Chickens

An experiment was conducted to study the adjuvant effect of ginsenosides on the recombinant refractile body antigen SO7 in coccidian-infected AA broilers. Five, days old chickens were subcutaneously immunized with SO7 antigen (100 mu g per chick) mixed with various doses of ginsenosides or without adjuvant. A boost of the same dose was given at 12 and 19 days of age. The specific antibody response and lymphocyte proliferation response to SO7 antigen were measured periodically postimmunization. Chickens in all groups were orally challenged with 1 x 10(5) homologous sporulated oocysts of E. tenella at 26 days of age and killed at eight days postchallenge. Results showed that when immunized by antigen adjuvanted with ginsenosides, lymphocyte proliferation was significantly enhanced at 19, 26 days of age and antibody response was obviously observed at 12, 19 and 26 days of age. All groups administered with antigen mixed in adjuvant showed higher protective immunity compared to PBS or nonadjuvanted antigen control in terms of lower mortality, oocyst output, lesion score and higher weight gain. A linear dose relationship was observed in terms of lesion score among three groups immunized with various doses of ginsenosides (p<0.05) in which the group given adjuvanted antigen with 1.0 mg ginsenosides showed significantly stronger adjuvant effects. These results suggest that ginsenosides has a strong adjuvant effect at a appropriate dose and may potentially serve as a vaccine adjuvant against avian coccidiosis.