Journal of Vaccines & Vaccination

Abstract

Immunization of Female Mice with a Plasmid DNA Vaccine Coding Eight Repeats of Gonadotrophin Releasing Hormone (Gnrh-I) and Eight T-Helper Epitopes Suppress Fertility In Vivo

Mohammad Abu Hadi Khan, Umme Kulsum Rima, Tadashi Kimura, Ayman M Gebril, Mohammad Taimur Islam, Abu Saleh Mahfuzul Bari and Valerie Anne Ferro

Induction of an appropriate immune response against gonadotrophin releasing hormone (GnRH-I) disrupt fertility, reduce fecundity and regress tumours of reproductive system.To disrupt fertility a plasmid DNA vaccine was engineered coding eight repeats of GnRH-I and eight T-helper epitopes. Translation efficiency of the vaccine was evaluated in undifferentiated COS1 cells and found to release GnRH-I fusion protein in culture supernatant. Swiss albino female mice (N=24) were immunized with 50μg plasmid DNA construct in study weeks 0, 3, 6, 9 and 12. Group 2 mice were primed with the plasmid DNA in hemagglutinating virus of japanese envelope (HVJE) vector and subsequent boosts were carried out in phosphate buffer saline. Group 3 mice were immunized with the plasmid DNA in non-ionic surfactant vesicles (NISV) and Group 1 was served as untreated control. The effect of immunization was studied in terms of anti-GnRH-I antibody response (OD value at A540 ± SD), suppression of ovarian folliculogenesis, altered uterine histoarchitecture and impaired fertility in vivo in mating trials. In study week 24 OD values of anti- GnRH-I antibody response were 0.982 ± 0.231 in Group 3 mice, followed by 0.783 ± 0.191 in Group 2 in comparison with no response in Group 1 controls (0.237 ± 0.147). Results of mating trials showed conception failure in vaccinated mice; 51, 18 and 05 pups were seen in the uteri of Groups 1, 2 and 3 mice respectively. There was significant (p>0.001) reduction in the weight of ovaries in Group 2 (8.50 ± 2.38 mg) and Group 3 (7.25 ± 0.95 mg) mice compared to Group 1 control (15.00 ± 1.41 mg). Significant reduction of ovarian folliculogenesis was seen in Group 2 (p>0.001) and Group 3 mice (p>0.01). In conclusion, the plasmid DNA vaccine delivered in female mice with HVJE and NISV induced significantly (p>0.001) higher levels of anti-GnRH-I antibody response, suppressed ovarian and uterine function and impaired fertility in vivo.