title: Efficacy of antibodies against a chimeric synthetic peptide encompassing epitopes of bonnet monkey (Macaca radiata) zona pellucida-1 and zona pellucida-3 glycoproteins to inhibit in vitro human sperm-egg binding.
abstract: Immunocontraception achieved by immunization with zona pellucida (ZP) glycoproteins is invariably associated with ovarian dysfunction. Use of ZP glycoprotein-based synthetic peptides as immunogens has been proposed to overcome adverse side effects on ovaries. In the present study, a chimeric peptide encompassing the epitopes of bonnet monkey (Macaca radiata) ZP glycoprotein-1 (bmZP1; amino acid residues 251-273) and ZP glycoprotein-3 (bmZP3; amino acid residues 324-347), separated by a tri-glycine spacer, was synthesized and conjugated to diphtheria toxoid (DT). Immunization of female BALB/cJ mice and bonnet monkeys with the chimeric peptide led to generation of antibodies that reacted with the chimeric peptide, individual bmZP1 & bmZP3 peptides, and also recombinant bmZP1 and bmZP3 proteins expressed by E. coli in an ELISA. Indirect immunofluorescence studies revealed that the immune serum also recognized human as well as bonnet monkey ZP. A significant inhibition of human sperm binding to ZP was observed with antibodies generated against the chimeric peptide in mice (P = 0.0001) as well as monkeys (P = 0.0002) in a hemizona assay (HZA). The inhibition efficacy was significantly higher than that observed by using antibodies against the individual bmZP1 and bmZP3 peptides. Interestingly, no ovarian pathology was observed in female bonnet monkeys immunized with the chimeric peptide. These studies have demonstrated that the chimeric peptide encompassing peptides of multiple ZP glycoproteins may be a promising candidate antigen for designing immunocontraceptive vaccines.
authors.affiliation: Gamete Antigen Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110 067, India.
authors.forename: Neela
authors.initials: N
authors.lastname: Sivapurapu
authors.forename: Akiko
authors.initials: A
authors.lastname: Hasegawa
authors.forename: Gagandeep K
authors.initials: GK
authors.lastname: Gahlay
authors.forename: Koji
authors.initials: K
authors.lastname: Koyama
authors.forename: Satish K
authors.initials: SK
authors.lastname: Gupta
mesh_terms: D000595:Amino Acid Sequence; D000704:Analysis of Variance; D000818:Animals; D000910:Antibodies, Heterophile / Q000378:metabolism*; D003269:Contraception, Immunologic / Q000379:methods*; D004527:Egg Proteins / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008255:Macaca radiata; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010053:Ovary / Q000187:drug effects / Q000473:pathology; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism / Q000494:pharmacology*; D013084:Sperm-Ovum Interactions / Q000187:drug effects*; D000072216:Zona Pellucida Glycoproteins
chemical_list: D000910:Antibodies, Heterophile; D004527:Egg Proteins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D000072216:Zona Pellucida Glycoproteins