The mammalian oocyte is surrounded by an extra-cellular matrix, the zona pellucida (ZP), composed of three major
glycoproteins (ZP1, ZP2 and ZP3). The ZP
glycoproteins, by virtue of their tissue specificity and critical role during mammalian fertilization, have emerged as potential candidate
antigens for the development of an immunocontraceptive
vaccine. Molecular characterization of ZP
glycoproteins from several species, reveals a variable degree of homology among the deduced primary amino acid sequences, which provided an opportunity to undertake active immunization studies in heterologous animal models. Active immunization of various animal species with either native ZP
glycoproteins or those obtained by
recombinant DNA technology led to the inhibition of fertility. Thus ZP
glycoproteins based immunocontraceptive
vaccines offer an attractive proposition for controlling wild life population. To make it a practical proposition, additional research inputs are required to optimize and devise novel strategies for
vaccine delivery. Observed ovarian dysfunction, often associated with immunization by ZP
glycoproteins is one of the major stumbling blocks for their use in humans. Ongoing studies to delineate appropriate
B cell epitopes of ZP
glycoproteins that are devoid of oophoritogenic
T-cell epitopes, which will inhibit fertility without concomitant
oophoritis, will be critical to determine their feasibility for human use.