Effect of diammonium glycyrrhizinate and oxymatrine adjuvant on humoral immune response induced by hepatitis A virus antigen in mice

Objective To investigate the effect of diammonium glycyrrhizinate and oxymatrine adjuvant on humoral immune response induced by hepatitis A virus(HAV)antigen in mice. Methods The two kinds of adjuvant,each at low(100 μg),moderate(500 μg)and high(1 mg)dosages,were mixed with 18 EU HAV antigen separately and immunized s. c. to ICR mice in several sites,using 200 μl physiological saline,HAV antigen(18 EU)and aluminum adjuvant(300 μg aluminum adjuvant + 18 EU HAV antigen)as controls,nine groups in total. Serum samples were collected at weeks 4,8,12 and 16 after immunization and determined for anti-HAV IgG levels by ELISA. The mice were killed at week 16 after immunization,and the heart,liver,spleen,lung and kidney tissues of mice immunized with diammonium glycyrrhizinate and oxymatrine adjuvant at optimal dosages as well as those in physiological saline control group were subjected to pathological examination. Results Anti-HAV IgGs were detected in the sera of mice in various groups except physiological saline control group. The IgG levels,excepted those in diammonium glycyrrhizinate moderate dosage and oxymatrine low dosage groups,reached the maximums at weeks 8. The serum anti-HAV IgG levels of mice immunized with diammonium glycyrrhizinate at various dosages were significantly higher than that in HAV antigen control group(P 0. 05),of which that in diammonium glycyrrhizinate low dosage group was the highest and was higher than that in aluminum adjuvant control group at week 8. However,the serum IgG levels of mice in oxymatrine groups at various weeks were significantly higher than those in HAV antigen group(P 0. 05),of which that in oxymatrine low dosage group was the highest and reached the maximum at week 12. No abnormalities were observed during the whole study,and no pathological changes were observed in various tissues. Conclusion Both diammonium glycyrrhizinate and oxymatrine adjuvant enhanced the humoral immune responses induced by HAV antigen in mice,which might be developed as novel adjuvant of vaccines.