关键词: 日本血吸虫, 脂肪酸结合蛋白, 白细胞介素-12, DNA疫苗, 免疫保护性, 佐剂

Abstract: Objective To study the immune protection of Schistosoma japonicum fatty acid binding protein （Sj14FABP） DNA vaccine enhanced by IL-12. Methods The recombinant plasmids pVIVO2-Sj14FABP and pVIVO2-IL12-Sj14FABP were constructed respectively, and were prepared on a large scale after identification. 48 male BALB/c mice were divided into 4 groups randomly. In group A, B, C, and D, each mouse was injected intramuscularly with 100　μl 0.9% NaCl, 100μg pVIVO2, 100μg pVIVO2-Sj14FABP and 100　μg pVIVO2-IL12-Sj14FABP respectively. 30 days after immunization each mouse was challenged with 40±2 cercariae of S. japonicum. On day 45 after challenge, all mice were sacrificed to count the number of recovered adult worms and the hepatic eggs. Sera from mice were used to detect IgG antibody. The production of IL-2, IL-4 and IFN-γ in the supernatant of spleen cells was observed by means of sandwich ABC-ELISA. Results The recombinant plasmids pVIVO2-Sj14FABP and pVIVO2-IL12-Sj14FABP were constructed. The worm reduction rate in group C and D was 24.11% and 39.4%, as well as liver egg reduction rate of 27.2% and 32.8% respectively. The level of IL-2 and IFN-γ in group D increased significantly, while IL-4 secretion decreased(P<0.01). 30 days after immunization, no higher titer of IgG antibody was shown in all groups. Furthermore, no significant difference on the level of IgG was found among the groups (P>0.05). Conclusion Sj14FABP DNA vaccine induces partial protective immunity in BALB/c mice. IL-12 drives the immune response toward a Th1 direction, and enhances the protective immune effect of the vaccine.

Key words: Schistosoma japonicum, Fatty acid binding protein, IL-12, DNA vaccine, Immune protection, Adjuvant