GnRH-pokeweed antiviral protein treatment for permanent non-surgical castration of sheep and cattle Professor Michael J. D.Occhio, University of Queensland

Summary

The project aimed to develop a single treatment protocol involving pokeweed antiviral protein (PAP) to give permanent non-surgical castration in rams and bulls. PAP belongs to a class of compounds which have the common feature of causing cell death. In the use of PAP for non-surgical castration, it is chemically linked to a compound that allows PAP to specifically enter cells in the pituitary gland that produce hormones that are essential for reproduction. The death of these cells in the pituitary results in the suppression of reproductive functions and animals essentially become castrates but without removal of the testes. 
Initially the project aimed to conjugate naturally occurring Pokeweed antigen to GnRH. After some preliminary work it was established that this was not technically feasible. The intention then was to create recombinant GnRH-PAP and conduct a proof of concept study. This would have incurred extra costs and a decision was made to abandon the project and submit a new proposal with the recombinant conjugate and a fresh program of R&D. This step was not taken and only the initial payment of $40,000 was made. The project was terminated in January 2013 by mutual consent.
Project objectives: 
Identify the optimal dose of GnRH-PAP to achieve cessation of testicular function in both prepubertal and sexually mature rams;
Demonstrate the duration of activity of GnRH-PAP in both prepubertal and sexually mature rams.Identify the optimal dose of GnRH-PAP to achieve long lasting cessation of testicular function in prepubertal bulls;
Demonstrate the duration of activity of GnRH-PAP in prepubertal bullsIdentification of potential commercial partners and development of a proposal to undertake further trials necessary for drug registration using the MLA Partners in Innovation mechanism.