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-C, 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.

Ovarian function and pregnancy outcome in pony mares following immunocontraception with native and recombinant porcine zona pellucida vaccines

“…A recombinant zona pellucida vaccine may provide potential advantages compared with native pZP vaccines that include production efficiency and the avoidance of contamination with non-ZP proteins [14]. Recently, recombinant vaccines based on the expression of porcine ZP3 and ZP4 in Escherichia coli, hereafter referred to as reZP, were developed [15].…”

Immunogenicity and Contraceptive Efficacy of Escherichia coli‐Expressed Recombinant Porcine Zona Pellucida Proteins

“…Zona pellucida (ZP) glycoproteins by virtue of their critical role during fertilization have been proposed as candidates for the development of contraceptive vaccine . In mammals, ZP matrix is comprised of either 3 or 4 glycoproteins.…”

Human Contraceptives: Current Status, Sperm Antigen Inhibitors and an Insight into PCSK4

“…Inhibition of gamete function, such as debilitating the function of sperm using ASA, has also been seen as one promising alternative of immuno-contraceptive approach [21,[25][26][27]. ASA were discovered in 2-30% of either infertile men or in their women partners and in 70% of men following vasectomy [21,25,28,29].…”