Nasal immunization with diphtheria toxoid conjugated-CD52 core peptide induced specific antibody production in genital tract of female mice

PROBLEM: The common mucosal immune system (CMIS) has developed as a barrier for the numerous encounters between the host and various pathogens. It is possible to exploit this system to induce secretion of IgA antibody which inhibits sperm penetration in the female genital tract. In this study, the immunogenicity of a human sperm surface antigen (CD52) introduced by intranasal immunization was investigated with a view to developing a contraceptive vaccine. METHOD OF STUDY: A synthetic peptide corresponding to CD52 core peptide (GQNDTSQTSSPS) was prepared and conjugated with diphtheria toxoid (DT) as a carrier protein. The immunogen was given to mice with DOTAP:cholesterol liposome adjuvant intranasally, followed by determination of Ig and IgA class antibody levels in the sera and vaginal washes. RESULTS: The CD52 core peptide elicited IgA class as well as Ig antibodies both in the sera and vaginal secretions after intranasal immunization. An additional nasal inoculation after decrease of the antibody titer raised the antibody level to its highest level during the experiment. CONCLUSIONS: These results indicate that the CMIS could induce Ig and IgA class antibodies reactive to CD52 core peptide in the female genital tract. Intranasal immunization of a sperm-specific antigen would be a promising regimen for a safe and easy contraceptive vaccine.