RESUMO
Objective:To investigate the immune effects of Clostridium difficile toxoid B (CdtB) vaccine formulated with different mucosal adjuvants through microneedle immunization, and to provide ideas for the prevention and treatment of Clostridium difficile infection. Methods:CdtB vaccine was prepared with purified Clostridium difficile toxin B(TcdB) after formaldehyde detoxification. Female BALB/c mice were immunized with different doses of vaccine alone or in combination with mucosal adjuvants. The titers of specific serum IgG and fecal IgA were detected at 0 d, 7 d, 14 d, 28 d and 42 d after immunization. The protective effects of CdtB vaccine were evaluated by cell neutralization assay and Clostridium difficile challenge infection. Results:(1) With the increase of immune dose, the mice immunized with CdtB vaccine alone by microneedle not only produced better serum specific IgG, but also had higher level of IgA in feces. (2) When the mice were immunized with CdtB vaccine containing LT or CTB adjuvant by microneedle, the trend of serum specific IgG titer in each group increased with the increase of immune dose, especially in the group containing LT adjuvant. There were significant differences in the trend of specific IgA titer in feces between the adjuvant groups and the group without adjuvant, but the adjuvant effect was not obvious. (3) No significant difference in serum IgG titer was observed between the mice immunized with 10 μg CdtB by microneedle or intraperitoneal injection, but microneedle immunization significantly increased fecal IgA level. (4) The neutralization titers of specific antibodies in mouse serum after immunization and the test results of challenge protection in mice confirmed that the use of CdtB vaccine had certain protective effects.Conclusions:CdtB vaccine had better immune effects in mice through microneedle immunization, but the adjuvant effects of LT and CTB were not significant.