Vaccines for immunological control of fertility

Abstract

Vaccines have been proposed as one of the strategies for population control. Immunocontraceptive vaccines can be designed to inhibit: (1) production of gametes (sperm and egg); (2) functions of gametes, leading to blocking of fertilization; and (3) gamete outcome (pregnancy). Immunization with gonadotropin-releasing hormone coupled to different carriers has shown curtailment in the production of sperm with concomitant infertility in various species. Immunization of nonhuman primates and men with ovine follicle stimulating hormone has also resulted in reduced sperm output. Various spermatozoa-specific proteins such as FA1, PH-20, LDH-C₄, SP-10, SP-17, sp56, SPAG9, and Izumo have been proposed as candidate antigens to develop contraceptive vaccines, which have shown efficacy in inhibiting fertility in different animal models. Immunization with zona pellucida glycoproteins-based immunogens also results in curtailment of fertility in a variety of species. However, ways to overcome the observed oophoritis associated with zona proteins immunization have yet to be discovered, a necessary step before their proposal for control of human population. Nonetheless, this is a very promising approach to control wildlife animal population. Phase II clinical trials of β-human chorionic gonadotropin-based vaccine in women have established the proof of principle that it is possible to inhibit fertility without any untoward side-effects by vaccination. Further scientific inputs are required to increase the efficacy of contraceptive vaccines and establish their safety beyond doubt, before they can become applicable for control of fertility in humans.

References Dietz T, Rosa EA. Effects of population and affluence on CO₂ emissions. Proc Natl Acad Sci USA, 1997, 94, 175–179 10.1073/pnas.94.1.175 Bradley MP, Bird P Hardy DM Applications of fertility regulation for the management of wild and domestic species. Fertilization, 2002 San Diego Academic 401–415 Cowan PE, Tyndale-Biscoe CH. Australian and New Zealand mammal species considered to be pests or problems. Reprod Fertil Dev, 1997, 9, 27–36 10.1071/R96058 White RB, Eisen JA, Kasten TL, Fernald RD. Second gene for gonadotropin releasing hormone in humans. Proc Natl Acad Sci USA, 1998, 95, 305–309 10.1073/pnas.95.1.305 Yahalom D, Chen A, Ben-Aroya N, Rahimipour S, Kaganovsky E, Okon E et al. The gonadotrophin-releasing hormone family of neuropeptides in the brain of human, bovine and rat: identification of a third isoform. FEBS Lett, 1999, 463, 289–294 10.1016/S0014-5793(99)01638-5 Hodges JK, Hearn JP. Effects of immunization against luteinizing hormone releasing hormone on reproduction of the marmoset monkey Callithrix jacchus. Nature, 1977, 265, 746–748 10.1038/265746b0 Takahashi M, Ford JJ, Yoshinaga K, Greep RO. Active immunization of female rats with luteinizing hormone releasing hormone (LHRH). Biol Reprod, 1978, 18, 754–761 10.1095/biolreprod18.5.754 Oonk HB, Turkstra JA, Schaaper WM, Erkens JH, Schuitemaker-de Weerd MH, Nes A et al. New GnRH-like peptide construct to optimize efficient immunocastration of male pigs by immunocontraception of GnRH. Vaccine, 1998, 16, 1074–1082 10.1016/S0264-410X(98)80101-1 Miller LA, Johns BE, Killian GJ. Immunocontraception of white-tailed deer with GnRH vaccine. Am J Reprod Immunol, 2000, 44, 266–274 10.1111/j.8755-8920.2000.440503.x Curtis PD, Pooler RL, Richmond ME, Miller LA, Mattfeld GF, Quimby FW. Comparative effects of GnRH and porcine zona pellucida (PZP) immunocontraceptive vaccines for controlling reproduction in white-tailed deer (Odocoileus virginianus). Reprod Suppl, 2002, 60, 131–141 Jung MJ, Moon YC, Cho IH, Yeh JY, Kim SE, Chang WS et al. Induction of castration by immunization of male dogs with recombinant gonadotropin-releasing hormone (GnRH)-canine distemper virus (CDV) T helper cell epitope p35. J Vet Sci, 2005, 6, 21–24 Walker J, Ghosh S, Pagnon J, Colantoni C, Newbold A, Zeng W et al. Totally synthetic peptide-based immunocontraceptive vaccines show activity in dogs of different breeds. Vaccine, 2007, 25, 7111–7119 10.1016/j.vaccine.2007.07.047 Junaidi A, Williamson PE, Cummins JM, Martin GB, Blackberry MA, Trigg TE. Use of a new drug delivery formulation of the gonadotrophin-releasing hormone analogue Deslorelin for reversible long-term contraception in male dogs. Reprod Fertil Dev, 2003, 15, 317–322 10.1071/RD03039 Dunshea FR, Colantoni C, Howard K, McCauley I, Jackson P, Long KA et al. Vaccination of boars with a GnRH vaccine (Improvac) eliminates boar taint and increases growth performance. J Anim Sci, 2001, 79, 2524–2535 Simms MS, Scholfield DP, Jacobs E, Michaeli D, Broome P, Humphreys JE et al. Anti-GnRH antibodies can induce castrate levels of testosterone in patients with advanced prostate cancer. Br J Cancer, 2000, 83, 443–446 10.1054/bjoc.2000.1315 Parkinson RJ, Simms MS, Broome P, Humphreys JE, Bishop MC. A vaccination strategy for the long-term suppression of androgens in advanced prostate cancer. Eur Urol, 2004, 45, 171–175 10.1016/j.eururo.2003.10.007 Moudgal NR, Ravindranath N, Murthy GS, Dighe RR, Aravindan GR, Martin F. Long-term contraceptive efficacy of vaccine of ovine follicle-stimulating hormone in male bonnet monkeys (Macaca radiata). J Reprod Fertil, 1992, 96, 91–102 Moudgal NR, Jeyakumar M, Krishnamurthy HN, Sridhar S, Krishnamurthy H, Martin F. Development of male contraceptive vaccine—a perspective. Hum Reprod Update, 1997, 3, 335–346 10.1093/humupd/3.4.335 Moudgal NR, Murthy GS, Prasanna Kumar KM, Martin F, Suresh R, Medhamurthy R et al. Responsiveness of human male volunteers to immunization with ovine follicle stimulating hormone vaccine: results of a pilot study. Hum Reprod, 1997, 12, 457–463 10.1093/humrep/12.3.457 Baskin MJ. Temporary sterilization by injection of human spermatozoa: a preliminary report. Am J Obstet Gynecol, 1932, 24, 892–897 Edwards RG. Immunological control of fertility in female mice. Nature, 1964, 203, 50–53 10.1038/203050a0 Ingerslev HJ. Antibodies against spermatozoal surface-membrane antigens in female infertility. Acta Obstet Gynecol Scand Suppl, 1981, 100, 1–52 10.3109/00016348109156938 Ohl D, Naz RK. Infertility due to antisperm antibodies. J Urol, 1995, 46, 591–602 10.1016/S0090-4295(99)80282-9 Primakoff P, Lathrop W, Wollman L, Cowan A, Myles D. Fully effective contraception in male and female guinea pigs immunized with the sperm protein PH-20. Nature, 1988, 335, 543–547 10.1038/335543a0 Herr JC, Flickinger CJ, Homyk M. Biochemical and morphological characterization of intra-acrosomal antigen SP-10 from human sperm. Biol Reprod, 1990, 42, 181–189 10.1095/biolreprod42.1.181 Lea IA, Lierop MJ, Widgren EE, Grootenhuis A, Wen Y, Duin M. A chimeric sperm peptide induces antibodies and strain-specific reversible infertility in mice. Biol Reprod, 1998, 59, 527–536 10.1095/biolreprod59.3.527 Hardy CM, Mobbs KJ. Expression of recombinant mouse sperm protein sp56 and assessment of its potential for use as an antigen in an immunocontraceptive vaccine. Mol Reprod Dev, 1999, 52, 216–224 10.1002/(SICI)1098-2795(199902)52:2<216::AID-MRD13>3.0.CO;2-R Zhu X, Naz RK. Fertilization antigen-1: cDNA cloning, testis-specific expression, and immunocontraceptive effects. Proc Natl Acad Sci USA, 1997, 94, 4704–4709 10.1073/pnas.94.9.4704 Suri A. Family of sperm associated antigens: relevance in sperm-egg interaction and immunocontraception. Soc Reprod Fertil Suppl, 2007, 63, 433–443 Naz RK. The fertilization antigen (FA-1) causes a reduction of fertility in actively immunized female rabbits. J Reprod Immunol, 1987, 11, 117–133 10.1016/0165-0378(87)90016-7 O'Hearn PA, Liang ZG, Bambra CS, Goldberg E. Colinear synthesis of an antigen-specific B-cell epitope with a ‘promiscuous’ tetanus toxin T-cell epitope: a synthetic peptide immunocontraceptive. Vaccine, 1997, 15, 1761–1766 10.1016/S0264-410X(97)00105-9 Tollner TL, Overstreet JW, Branciforte D, Primakoff PD. Immunization of female cynomolgus macaques with a synthetic epitope of sperm-specific lactate dehydrogenase results in high antibody titres but does not reduce fertility. Mol Reprod Dev, 2002, 62, 257–264 10.1002/mrd.10063 O'Rand MG, Widgren EE, Sivashanmugam P, Richardson RT, Hall SH, French FS et al. Reversible immunocontraception in male monkeys immunized with Eppin. Science, 2004, 306, 1189–1190 10.1126/science.1099743 Naz RK, Zhu X, Kadam AL. Identification of human sperm peptide sequence involved in egg binding for immunocontraception. Biol Reprod, 2000, 62, 318–324 10.1095/biolreprod62.2.318 Naz RK, Chauhan SC. Human sperm-specific peptide vaccine that causes long-term reversible contraception. Biol Reprod, 2002, 67, 674–680 10.1095/biolreprod67.2.674 Hardy CM, Pekin J, ten Have J. Mouse-specific immunocontraceptive polyepitope vaccines. Reprod Suppl, 2002, 60, 19–30 Naz RK. Immunocontraceptive effect of Izumo and enhancement by combination vaccination. Mol Reprod Dev, 2008, 75, 336–344 10.1002/mrd.20783 Inoue N, Ikawa M, Isotani A, Okabe M. The immunoglobulin superfamily protein Izumo is required for sperm to fuse with eggs. Nature, 2005, 434, 234–238 10.1038/nature03362 Wang M, Lv Z, Shi J, Hu Y, Xu C. Immunocontraceptive potential of the Ig-like domain of Izumo. Mol Reprod Dev, 2009, 76, 794–801 10.1002/mrd.21027 Wassarman PM, Litscher ES. Mammalian fertilization: the egg's multifunctional zona pellucida. Int J Dev Biol, 2008, 52, 665–676 10.1387/ijdb.072524pw Beebe SJ, Leyton L, Burks D, Ishikawa M, Fuerst T, Dean J et al. Recombinant mouse ZP3 inhibits sperm binding and induces the acrosome reaction. Dev Biol, 1992, 151, 48–54 10.1016/0012-1606(92)90212-Y Bleil JD, Wassarman PM. Mammalian sperm-egg interaction: identification of a glycoprotein in mouse egg zonae pellucidae possessing receptor activity for sperm. Cell, 1980, 20, 873–882 10.1016/0092-8674(80)90334-7 Bleil JD, Greve JM, Wassarman PM. Identification of a secondary sperm receptor in the mouse egg zona pellucida: role in maintenance of binding of acrosome-reacted sperm to eggs. Dev Biol, 1988, 128, 376–385 10.1016/0012-1606(88)90299-0 Izquierdo-Rico MJ, Jimenez-Movilla M, Llop E, Perez-Oliva AB, Ballesta J, Gutierrez-Gallego R et al. Hamster zona pellucida is formed by four glycoproteins: ZP1, ZP2, ZP3 and ZP4. J Proteome Res, 2009, 8, 926–941 10.1021/pr800568x Ganguly A, Sharma RK, Gupta SK. Bonnet monkey (Macaca radiata) ovaries, like human oocytes, express four zona pellucida glycoproteins. Mol Reprod Dev, 2008, 75, 156–166 10.1002/mrd.20808 Hoodbhoy T, Joshi S, Boja ES, Williams SA, Stanley P, Dean J. Human sperm do not bind to rat zonae pellucidae despite the presence of four homologous glycoproteins. J Biol Chem, 2005, 280, 12721–12731 10.1074/jbc.M413569200 Hughes DC, Barratt CL. Identification of the true human orthologue of the mouse Zp1 gene: evidence for greater complexity in the mammalian zona pellucida?. Biochim Biophys Acta, 1999, 1447, 303–306 Lefievre L, Conner SJ, Salpekar A, Olufowobi O, Ashton P, Pavlovic B et al. Four zona pellucida glycoproteins are expressed in the human. Hum Reprod, 2004, 19, 1580–1586 10.1093/humrep/deh301 Chakravarty S, Kadunganattil S, Bansal P, Sharma RK, Gupta SK. Relevance of glycosylation of human zona pellucida glycoproteins for their binding to capacitated human spermatozoa and subsequent induction of acrosomal exocytosis. Mol Reprod Dev, 2008, 75, 75–88 10.1002/mrd.20726 Chiu PC, Wong BS, Chung MK, Lam KKW, Pang RT, Lee KF et al. Effects of native human zona pellucida glycoprotein-3 and -4 on acrosome reaction and zona pellucida binding of human spermatozoa. Biol Reprod, 2008, 79, 869–877 10.1095/biolreprod.108.069344 Caballero-Campo P, Chirinos M, Fan XJ, González-González ME, Galicia-Chavarría M, Larrea F et al. Biological effects of recombinant human zona pellucida proteins on sperm function. Biol Reprod, 2006, 74, 760–768 10.1095/biolreprod.105.047522 Chakravarty S, Kadunganattil S, Gupta SK. Baculovirus-expressed recombinant human zona pellucida glycoprotein-B induces acrosomal exocytosis in capacitated spermatozoa in addition to zona pellucida glycoprotein-C. Mol Hum Reprod, 2005, 11, 365–372 10.1093/molehr/gah165 Sacco AG, Yurewicz EC, Subraminian MG, DeMayo FJ. Zona pellucida composition: species cross reactivity and contraceptive potential of antiserum to a purified pig zona antigen (PPZA). Biol Reprod, 1981, 25, 997–1008 10.1095/biolreprod25.5.997 Wood DM, Liu C, Dunbar BS. Effect of alloimmunization and heteroimmunization with zona pellucidae on fertility in rabbits. Biol Reprod, 1981, 25, 439–450 10.1095/biolreprod25.2.439 Mahi-Brown CA, Huang TT Jr, Yanagimachi R. Infertility in bitches induced by active immunization with porcine zonae pellucidae. J Exp Zool, 1982, 222, 89–95 10.1002/jez.1402220112 Gulyas BJ, Yuan LC, Gwatkin RB, Schmell ED. Response of monkeys to porcine zona pellucida as detected by a solid-phase radioimmunoassay. J Med Primatol, 1983, 12, 331–342 Sacco AG, Pierce DL, Subramanian MG, Yurewicz EC, Dukelow WR. Ovaries remain functional in squirrel monkeys (Saimiri sciureus) immunized with porcine zona pellucida 55,000 macromolecule. Biol Reprod, 1987, 36, 481–490 10.1095/biolreprod36.2.481 Sacco AG, Yurewicz EC, Subramanian MG. Effect of varying dosage and adjuvants on antibody response in squirrel monkeys (Saimiri sciureus) immunized with the porcine zona pellucida Mr = 55,000 glycoprotein (ZP3). Am J Reprod Immunol, 1989, 21, 1–8 Upadhyay SN, Thillai-Koothan P, Bamezai A, Jayaraman S, Talwar GP. Role of adjuvants in inhibitory influence of immunization with porcine zona pellucida antigen (ZP3) on ovarian folliculogenesis in bonnet monkeys: a morphological study. Biol Reprod, 1989, 41, 665–673 10.1095/biolreprod41.4.665 Bagavant H, Thillai-Koothan P, Sharma MG, Talwar GP, Gupta SK. Antifertility effects of porcine zona pellucida-3 immunization using permissible adjuvants in female bonnet monkeys (Macaca radiata): reversibility, effect on follicular development and hormonal profiles. J Reprod Fertil, 1994, 102, 17–25 10.1530/jrf.0.1020017 Paterson M, Wilson MR, Morris KD, Duin M, Aitken RJ. Evaluation of the contraceptive potential of recombinant human ZP3 and human ZP3 peptides in a primate model: their safety and efficacy. Am J Reprod Immunol, 1998, 40, 198–209 Martinez ML, Harris JD. Effectiveness of zona pellucida protein ZPB as an immunocontraceptive antigen. J Reprod Fertil, 2000, 120, 19–32 10.1530/reprod/120.1.19 Govind CK, Gupta SK. Failure of female baboons (Papio anubis) to conceive following immunization with recombinant non-human primate zona pellucida glycoprotein-B expressed in Escherichia coli. Vaccine, 2000, 18, 2970–2978 10.1016/S0264-410X(00)00103-1 Govind CK, Srivastava N, Gupta SK. Evaluation of the immunocontaceptive potential of Escherichia coli expressed recombinant non-human primate zona pellucida glycoproteins in homologous animal model. Vaccine, 2002, 21, 78–88 10.1016/S0264-410X(02)00438-3 Lou AM, Garza KM, Hunt D, Tung KS. Antigen mimicry in autoimmune disease sharing of amino acid residues critical for pathogenic T cell activation. J Clin Invest, 1993, 92, 2117–2123 10.1172/JCI116812 Hinsch E, Hagele W, Bohle RM, Schill WB, Hinsch KD. Evaluation of ZP2 domains of functional importance with antisera against synthetic ZP2 peptides. J Reprod Fertil, 1998, 114, 245–251 Sun W, Lou YH, Dean J, Tung KS. A contraceptive peptide vaccine targeting sulfated glycoprotein ZP2 of the mouse zona pellucida. Biol Reprod, 1999, 60, 900–907 10.1095/biolreprod60.4.900 Hasegawa A, Hamada Y, Shigeta M, Koyama K. Contraceptive potential of synthetic peptides of zona pellucida protein (ZPA). J Reprod Immunol, 2002, 53, 91–98 10.1016/S0165-0378(01)00084-5 Sivapurapu N, Upadhyay A, Hasegawa A, Koyama K, Gupta SK. Native zona pellucida reactivity and in vitro effect on human sperm-egg binding with antisera against bonnet monkey ZP1 and ZP3 synthetic peptides. J Reprod Immunol, 2002, 56, 77–91 10.1016/S0165-0378(02)00023-2 Ringleb J, Rohleder M, Jewgenow K. Impact of feline zona pellucida glycoprotein B-derived synthetic peptides on in vitro fertilization of cat oocytes. Reproduction, 2004, 127, 179–186 10.1530/rep.1.00076 Lou Y, Ang J, Thai H, McElveen F, Tung KS. A zona pellucida 3 peptide vaccine induces antibodies and reversible infertility without ovarian pathology. J Immunol, 1995, 155, 2715–2720 Paterson M, Wilson MR, Jennings ZA, Duin M, Aitken RJ. Design and evaluation of a ZP3 peptide vaccine in a homologous primate model. Mol Hum Reprod, 1999, 5, 342–352 10.1093/molehr/5.4.342 Kaul R, Sivapurapu N, Afzalpurkar A, Srikanth V, Govind CK, Gupta SK. Immunocontraceptive potential of recombinant bonnet monkey (Macaca radiata) zona pellucida glycoprotein-C expressed in Escherichia coli and its corresponding synthetic peptide. Reprod Biomed Online, 2001, 2, 33–39 10.1016/S1472-6483(10)62186-4 Miller LA, Killian GJ. In search of the active PZP epitope in white-tailed deer immunocontraception. Vaccine, 2002, 20, 2735–2742 10.1016/S0264-410X(02)00195-0 Hardy CM, ten Have JF, Mobbs KJ, Hinds LA. Assessment of the immunocontraceptive effect of a zona pellucida 3 peptide antigen in wild mice. Reprod Fertil Dev, 2002, 14, 151–155 10.1071/RD01112 Sivapurapu N, Hasegawa A, Gahlay GK, Koyama K, Gupta SK. 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. Mol Reprod Dev, 2005, 70, 247–254 10.1002/mrd.20202 Sivapurapu N, Upadhyay A, Hasegawa A, Koyama K, Gupta SK. Efficacy of antibodies against Escherichia coli expressed chimeric recombinant protein encompassing multiple epitopes of zona pellucida glycoproteins to inhibit in vitro human sperm-egg binding. Mol Reprod Dev, 2003, 65, 309–317 10.1002/mrd.10252 Hardy CM, Clydesdale G, Mobbs KJ. Development of mouse-specific contraceptive vaccines: infertility in mice immunized with peptide and polyepitope antigens. Reproduction, 2004, 128, 395–407 10.1530/rep.1.00276 Hardy CM, Beaton S, Hinds LA. Immunocontraception in mice using repeated, multi-antigen peptides: immunization with purified recombinant antigens. Mol Reprod Dev, 2008, 75, 126–135 10.1002/mrd.20745 Kirkpatrick JF, Liu IKM, Turner JW Jr. Remotely-delivered immunocontraception in feral horses. Wildl Soc Bull, 1990, 18, 326–330 Kirkpatrick JF, Zimmermann W, Kolter L, Liu IKM, Turner JN. Immunocontraception of captive exotic species. I. Przewalski's horse (Equus przewalskii) and banteng (Bos javanacus). Zoo Biol, 1995, 14, 403–413 10.1002/zoo.1430140503 McShea WJ, Monfort SL, Hakim S, Kirkpatrick JF, Liu IKM, Turner JW et al. Immunocontraceptive efficacy and the impact of contraception on the reproductive behaviors of white-tailed deer. J Wildl Manag, 1997, 61, 560–569 10.2307/3802615 Kirkpatrick JF, Turner A. Reversibility of action and safety during pregnancy of immunization against porcine zona pellucida in wild mares (Equus caballus). Reprod Suppl, 2002, 60, 197–202 Kirkpatrick JF, Turner A. Absence of effects from immunocontraception on seasonal birth patterns and foal survival among barrier island wild horses. J Appl Anim Welf Sci, 2003, 6, 301–308 10.1207/s15327604jaws0604_4 Curtis PD, Richmond ME, Miller LA, Quimby FW. Pathophysiology of white-tailed deer vaccinated with porcine zona pellucida immunocontraceptive. Vaccine, 2007, 25, 4623–4630 10.1016/j.vaccine.2007.03.033 Fayrer-Hosken RA, Grobler D, Altena JJ, Bertschinger HJ, Kirkpatrick JF. Immunocontraception of African elephants. Nature, 2000, 407, 149 10.1038/35025136 Srivastava N, Santhanam R, Sheela P, Mukund S, Thakral SS, Malik BS et al. Evaluation of the immunocontraceptive potential of Escherichia coli-expressed recombinant dog ZP2 and ZP3 in a homologous animal model. Reproduction, 2002, 123, 847–857 10.1530/rep.0.1230847 Turner JW Jr, Liu IK, Kirkpatrick JF. Remotely delivered immunocontraception in free-roaming feral burros (Equus asinus). J Reprod Fertil, 1996, 107, 31–35 10.1530/jrf.0.1070031 Brown RG, Bowen WD, Eddington JD, Kimmins WC, Mezei M, Parsons JL et al. Evidence for a long-lasting single administration contraceptive vaccine in wild grey seals. J Reprod Immunol, 1997, 35, 43–51 10.1016/S0165-0378(97)00047-8 Choudhury S, Kakkar V, Suman P, Chakrabarti K, Vrati S, Gupta SK. Immunogenicity of zona pellucida glycoprotein-3 and spermatozoa YLP(12) peptides presented on Johnson grass mosaic virus-like particles. Vaccine, 2009, 27, 2948–2953 10.1016/j.vaccine.2009.03.002 Zhang X, Lou YH, Koopman M, Doggett T, Tung KS, Curtiss R 3rd. Antibody responses and infertility in mice following oral immunization with attenuated Salmonella typhimurium expressing recombinant murine ZP3. Biol Reprod, 1997, 56, 33–41 10.1095/biolreprod56.1.33 Jackson RJ, Maguire DJ, Hinds LA, Ramshaw IA. Infertility in mice induced by a recombinant ectromelia virus expressing mouse zona pellucida glycoprotein 3. Biol Reprod, 1998, 58, 152–159 10.1095/biolreprod58.1.152 Lloyd ML, Shellam GR, Papadimitriou JM, Lawson MA. Immunocontraception is induced in BALB/c mice inoculated with murine cytomegalovirus expressing mouse zona pellucida 3. Biol Reprod, 2003, 68, 2024–2032 10.1095/biolreprod.102.012880 Gu W, Holland M, Janssens P, Seamark R, Kerr P. Immune response in rabbit ovaries following infection of a recombinant myxoma virus expressing rabbit zona pellucida protein B. Virology, 2004, 318, 516–523 10.1016/j.virol.2003.10.021 Rath A, Choudhury S, Hasegawa A, Koyama K, Gupta SK. Antibodies generated in response to plasmid DNA encoding zona pellucida glycoprotein-B inhibit in vitro human sperm-egg binding. Mol Reprod Dev, 2002, 62, 525–533 10.1002/mrd.10141 Rath A, Batra D, Kaur R, Vrati S, Gupta SK. Characterization of immune response in mice to plasmid DNA encoding dog zona pellucida glycoprotein-3. Vaccine, 2003, 21 (17–18) 1913–1923 10.1016/S0264-410X(02)00824-1 Choudhury S, Ganguly A, Chakrabarti K, Sharma RK, Gupta SK. DNA vaccine encoding chimeric protein encompassing epitopes of human ZP3 and ZP4: immunogenicity and characterization of antibodies. J Reprod Immunol, 2009, 79, 137–147 10.1016/j.jri.2008.09.002 Li J, Jin H, Zhang A, Li Y, Wang B, Zhang F. Enhanced contraceptive response by co-immunization of DNA and protein vaccines encoding the mouse zona pellucida 3 with minimal oophoritis in mouse ovary. J Gene Med, 2007, 9, 1095–1103 10.1002/jgm.1069 Fishel SB, Edwards RG, Evans CJ. Human chorionic gonadotropin secreted by preimplantation embryos cultured in vitro. Science, 1984, 223, 816–818 10.1126/science.6546453 Stenman UH, Alfthan H, Hotakainen K. Human chorionic gonadotropin in cancer. Clin Biochem, 2004, 37, 549–561 10.1016/j.clinbiochem.2004.05.008 Stevens VC, Powell JE, Lee AC, Griffin D. Antifertility effects of immunization of female baboons with C-terminal peptides of the beta-subunit of human chorionic gonadotropin. Fertil Steril, 1981, 36, 98–105 Stevens VC. Progress in the development of human chorionic gonadotropin antifertility vaccines. Am J Reprod Immunol, 1996, 35, 148–155 Jones WR, Bradley J, Judd SJ, Denholm EH, Ing RM, Mueller UW et al. Phase I clinical trial of a World Health Organisation birth control vaccine. Lancet, 1988, 1 (8598) 1295–1298 10.1016/S0140-6736(88)92117-4 Rock EP, Reich KA, Lyu DM, Hovi M, Hardy J, Schoolnik GK et al. Immunogenicity of a fusion protein linking the beta subunit carboxyl terminal peptide (CTP) of human chorionic gonadotropin to the B subunit of Escherichia coli heat-labile enterotoxin (LTB). Vaccine, 1996, 14, 1560–1568 10.1016/S0264-410X(96)00046-1 Cui C, Stevens VC, Schwendeman SP. Injectable polymer microspheres enhance immunogenicity of a contraceptive peptide vaccine. Vaccine, 2007, 25, 500–509 10.1016/j.vaccine.2006.07.055 Talwar GP, Sharma NC, Dubey SK, Salahuddin M, Das C, Ramakrishnan S et al. Isoimmunization against human chorionic gonadotropin with conjugates of processed beta-subunit of the hormone and tetanus toxoid. Proc Natl Acad Sci USA, 1976, 73, 218–222 10.1073/pnas.73.1.218 Nash H, Johansson ED, Talwar GP, Vasquez J, Segal S, Coutinho E et al. Observations on the antigenicity and clinical effects of a candidate antipregnancy vaccine: beta-subunit of human chorionic gonadotropin linked to tetanus toxoid. Fertil Steril, 1980, 34, 328–335 Gaur A, Arunan K, Singh O, Talwar GP. Bypass by an alternate carrier of acquired unresponsiveness to hCG upon repeated immunization with tetanus conjugated vaccine. Int Immunol, 1990, 2, 151–155 10.1093/intimm/2.2.151 Gupta A, Pal R, Ahlawat S, Bhatia P, Singh O. Enhanced Immunogenicity of a contraceptive vaccine using diverse synthetic carriers with permissible adjuvant. Vaccine, 2001, 19, 3384–3389 10.1016/S0264-410X(01)00079-2 Talwar GP, Singh O, Pal R, Chatterjee N, Sahai P, Dhall K et al. A vaccine that prevents pregnancy in women. Proc Natl Acad Sci USA, 1994, 91, 8532–8536 10.1073/pnas.91.18.8532 Singh M, Das SK, Suri S, Singh O, Talwar GP. Regain of fertility and normality of progeny born during below protective threshold antibody titers in women immunized with the HSD-hCG vaccine. Am J Reprod Immunol, 1998, 39, 395–398 Ehrlich PH, Bernard MP, Myers RV, Macdonald GJ, Moyle WR. Epitope-specific focusing of the immune response to a minimized human chorionic gonadotropin analog. Biochem Biophys Res Commun, 1998, 247, 315–318 10.1006/bbrc.1998.8758 Chiesa MD, Martensen PM, Simmins C, Porakishvili N, Justesen J, Dougan G et al. Refocusing of B cell response following a single amino acid substitution in an antigen. Immunology, 2001, 103, 172–178 10.1046/j.1365-2567.2001.01242.x Porakishvili N, Chiesa MD, Chikadze N, Martensen PM, Justensen J, Lund T et al. Elimination of the luteinizing hormone cross-reactive epitopes from human chorionic gonadotropin. Vaccine, 2002, 20, 2053–2059 10.1016/S0264-410X(02)00051-8 Wang XL, Zhao XR, Yu M, Yuan MM, Yao XY, Li DJ. Gene conjugation of molecular adjuvant C3d3 to hCGbeta increased the anti-hCG beta Th2 and humoral immune response in DNA immunization. J Gene Med, 2006, 8, 498–505 10.1002/jgm.871