Development of antifertility vaccine using sperm specific proteins

Area of Science:

• Reproductive immunology
• Contraceptive development
• Sperm biology

Background:

• Sperm proteins are implicated in fertilization; antibodies against them can cause infertility.
• Certain sperm proteins like LDH-C4, PH-20, and Eppin have been explored as contraceptive vaccine candidates.
• Previous candidates showed limited efficacy or adverse effects, necessitating further research.

Purpose of the Study:

• To evaluate the potential of human sperm antigen (80 kDa HSA) and its derived peptides as targets for a male contraceptive vaccine.
• To identify specific peptides of 80 kDa HSA that can induce infertility.

Main Methods:

• Active immunization of male and female rats with 80 kDa HSA.
• Enzymatic digestion of 80 kDa HSA to obtain N-terminal peptides (NT, 1, 2, 3, 4).
• Assessment of immunobiological activity and infertility induction by native protein and its peptides in rats and other animal models (rabbits, marmosets).

Main Results:

• Active immunization with 80 kDa HSA induced immunological infertility in rats.
• Peptides NT, 1, 2, and 4 mimicked the immunobiological activity of the native protein.
• Passive administration of antibodies to these peptides induced infertility; Peptide 1 was most effective.
• Active immunization with synthetic Peptide-1 conjugated to KLH impaired fertility in male rabbits and marmosets, with restoration upon antibody titer decline.

Conclusions:

• Synthetic Peptide-1 derived from 80 kDa HSA is a promising candidate for a male contraceptive vaccine.
• The immunogenicity and infertility-inducing capacity of Peptide-1 support its further development.
• Further research is warranted to assess long-term efficacy and safety in preclinical and clinical studies.