Evaluation Of Two Mucosal Immune Routes For Chitosan/zona Pellucida DNA Contraceptive Vaccine

Aim: To evaluate the mucosal immune response, antifertility effect and pathological change of ovarian induced by intranasal and vaginal immunization with zona pellucida DNA contraceptive vaccine, and explore the feasibility of overcoming ovary dysfunction, which was often caused by immunization of zona pellucida antigen, and improving contraceptive efficacy by inducing mucosal immunity using chitosan/pVAX1-pZP3α nanoparticles. Methods: Chitosan/pVAX1-pZP3α nanoparticles was prepared and administered into each experimental mouse on weeks 0,3 and 6 by intranasal and intravaginal respectively, whereas chitosan without DNA was given to control. Serum and vaginal washes samples collected every two weeks were used to determine anti-pZP3 IgA and IgG response by ELISA. On week 10, these female mice were mated with male mice and were checked for pregnant. On week 13, the mice were killed and ovarian serial section was prepared for microscopy. For study expression of the antigen of zona pellucida DNA vaccine in vivo, recombinant plasmid pEGFP-N1-pZP3α was constructed. Tracheas, lungs were moved from mice intranasally immunized by chitosan/pEGFP-N1-pZP3α nanoparticles and vaginas from vaginal group on day 2, 4, 6, 8, 10 and frozen section was prepared for fluorescence microscopy. Results: Anti-pZP3 IgA antibody response could be detected in serum and vaginal washes, intensity and lasting time varying over a wide range among different mouse. 8 mice (8/10) in intranasal group and 5 mice (5/7) in vaginal group didn't fall pregnant while the control did. Anti-fertility was relative to anti-pZP3 IgA antibody level in serum when mating mice. There was no difference about ovarian histology among unpregnant, pregnant experimental mice and control mice. No pathological changes were found in ovaries of immunized mice. Since day 4 after given plasmid pEGFP-N1-pZP3α, faint fluorescence detected in some epithelial cells of tracheas, lungs and vaginas indicated DNA expression in these tissues. Conclusion: Intranasal and vaginal immunization with chitosan/pVAX1-pZP3α nanoparticles could induce mucosal immune response ingenital tract and inhibit fertility without any effect on ovarian structure in mice. Inducing mucosal immunity would be a promising regimen for study of developing a safe zona pellucida contraceptive vaccine.