ABSTRACT
Objective:To observe the dynamic changes in specific IgG antibodies induced by recombinant hepatitis E vaccine using different immunization strategies in BALB/c mice.Methods:BALB/c, C57BL/6, NIH and KM mice were immunized intraperitoneally with serially diluted hepatitis E vaccine to select a mouse strain appropriately responding to hepatitis E vaccine. Then the selected BALB/c mice were randomly divided into three experimental groups, one-dose immunization group (0 week), two-dose immunization group (0 and 4 weeks) and three-dose immunization group (0, 4 and 12 weeks), and three adjuvant control groups with the same immunization strategy as the corresponding experimental group. Blood samples were collected from the intraocular canthus at different time points and serum antibody levels were detected quantitatively.Results:The BALB/c and NIH mice had proper responses to hepatitis E vaccine administrated at different doses than the C57BL/6 and KM mice, and the antibody positive conversion rates also showed a certain dose-effect relationship. Thus, the BALB/c mice were used as the animal model. The level of specific IgG antibodies in BALB/c mice immunized with one dose of vaccine reached a peak of 44.35 U/ml around the 10th week after the immunization, and then maintained at (5.52-13.28) U/ml after a decrease. The antibody level in the two-dose immunization group increased rapidly after the second immunization and peaked at the 8th week. From the 10th week, it gradually decreased and maintained at (16.50-32.54) U/ml. The trend of antibody changes in the three-dose immunization group was similar to that of the two-dose immunization group during the first 12 weeks, but a significant increase was induced after the third immunization and the level maintained at (62.65-72.61) U/ml for a long time, which was about nine times higher than that of the one-dose immunization group and three times of the two-dose immunization group.Conclusions:This study showed that BALB/c mice were suitable models to study the dynamic changes in specific IgG antibodies elicited by hepatitis E vaccine using different immunization strategies, which provided reference for future research on its in vivo efficacy.