Aim: To investigated whether fai3 as molecular adjuvant can enhance antifertility effect of contraceptive DNA vaccine pcD-Lzp3 through intranasal route.
Methods: FAI was a fibrinogen-albumin-IgG receptor of group C streptococci in which exhibits adjuvant properties. The third gene fragment of FAI-fai3 (415~702 bp) has the function of mucosal adjuvant. In this study, Plasmid pcD-Lzp3and pcD-fai3were encapsulated separately or together with chitosan to generate chitosan-DNA complexes, chi-pcD-Lzp3, chi-pcD-fai3, and chi-(pcD-Lzp3+ pcD-fai3), as the DNA vaccines. ICR mice were immunized with these chitosan nanoparticles, respectively, on day 0, 14, 28 and 42. Indirect ELISA was employed to determine the anti-Lzp3 specific IgG, IgG1and IgG2a antibody in sera, and the anti-Lzp3 specific IgA in vaginal secretion and the feces.
Results: The results showed that higher levels of serum IgG and mucosal secreted IgA were induced significantly in the mice of intranasally co-administered with chi-(pcD-Lzp3+pcD-fai3). The antifertility results showed that the mice of co-immunized group had the lowest birth rate and mean litter size.
Conclusion: The intranasal delivery of the molecular adjuvant fai3 with chi-pcD-Lzp3 could significantly enhance the antifertility of the Lzp3 DNA vaccine for contraception by enhancing both the systemic and mucosal immune responses.