Immunogenicity and contraceptive potential of three infertility-relevant zona pellucida 2 epitopes in the marsupial brushtail possum (Trichosurus vulpecula)

Abstract

In a previous study, three infertility-relevant epitopes of possum ZP2 (Pep12 (amino acids 111-125), Pep31 (amino acids 301-315), and Pep44 (amino acids 431-445)) were identified using sera from possums (Trichosurus vulpecula) immunized with recombinant possum zona pellucida 2 (ZP2) constructs, and a synthetic peptide library of possum ZP2 protein. In this study, the three peptides were conjugated to keyhole limpet hemocyanin and 300 mg of each conjugated peptide were administered subcutaneously to female possums (nZ20 per peptide) in complete Freund's adjuvant. Immunogen doses were repeated 3 and 6 weeks later using incomplete Freund's adjuvant. Control animals were immunized with either phosphate-buffered saline only (nZ10) or 300 mg keyhole limpet hemocyanin (nZ10), administered with the same adjuvants. Serum antibodies from animals immunized against these three epitopes bound to the corresponding possum ZP2 peptides, recombinant possum ZP2 protein constructs, and native zona. Possum fertility was assessed following superovulation and artificial insemination. Peptides Pep12 and Pep31 had no significant effects on fertility parameters (PO0.05). However, animals immunized with Pep44 had lower egg fertilization rates (immunized 19.5% versus control 60.5%, P!0.05) and produced significantly fewer embryos than control animals (immunized 0.5 embryos versus control 2.4 embryos, P!0.05). The number of Pep44-immunized females that produced embryos was reduced by 64%. Identification and characterization of possum infertility-relevant epitopes on possum ZP2 protein will assist development of safe, humane, and possum-specific immunocontraceptive vaccines for controlling the introduced possums in New Zealand.

Artificial insemination in marsupials

“…Artificial insemination and other ART will find continuing use as a research tool in situations like the screening of fertility control vaccines/agents as a means of non-lethal population control for the introduced brushtail possum in New Zealand and in areas with local overabundance of macropods in many regions of Australia and the Koala in Victoria and South Australia [11,86]. Also, with the growing importance of grey short-tailed opossum as a biomedical model and the availability of its genome [87], it is likely AI and other ART will be required to generate, cryo-bank, and reintroduce mutant/transgenic opossum strains in captive research colonies.…”

Development of a contraceptive vaccine for the marsupial brushtail possum (Trichosurus vulpecula): lack of effects in mice and chickens immunised with recombinant possum ZP3 protein and a possum ZP3 antifertility epitope

“…The ELISA procedures (Cui and Duckworth 2005;Duckworth et al 2007) were modified to measure antibody responses in animals vaccinated against possum rZP3 or pZP3e. For the rZP3 ELISA, binding of the rZP3 antibodies was measured using possum rZP3 .…”

Polymeric nanoparticles as an oral delivery system for biocontrol agents for the brushtail possum (Trichosurus vulpecula)

“…New agents for biological control of the brushtail possum in New Zealand, e.g. immunocontraceptives and chemical sterilants, are being investigated, and they are likely to be peptide or protein molecules (Duckworth et al 2007;Eymann et al 2007). Consequently, the design of a potential delivery system has been based on model macromolecules such as insulin.…”