Oral Vaccination and Immunocontraception of Feral Swine using Brucella suis with Multimeric GnRH Protein Expression

Abstract

As part of the Reproductive Control Methods Project, the USDA National Wildlife Research Center (NWRC) has developed multiple non-lethal contraceptive tools to control population of over-abundant wildlife species. Working in conjunction with Dr. G. P. Talwar of the Talwar Research Institute in India, scientists at NWRC have shown that a recombinant form of GnRH peptide has successfully contracepted swine. Feral swine not only pose a significant agricultural issue due to over-population; they act as a reservoir for Brucella suis, a threat to domestic livestock and humans. The Brucella abortus RB51 (Rough Brucella) vaccine, developed for bovine brucellosis and licensed by the USDA Animal Plant Health Inspection Service, has shown protection for some swine and is also effective against Brucella suis infection and other antigens. There is currently no approved vaccine for swine brucellosis (feral or domestic) in the United States. Past studies performed at The Ohio State University show that Brucella suis vaccination appears to protect against abortion and colonization in pigs after a virulent challenge. The Talwar recombinant peptide consists of 5 LHRH peptides interspersed with 4 universally immunogenic “promiscuous” T-cell epitopes of diverse genetic background. By transforming the Brucella suis strain with the Talwar recombinant LHRH plasmid, the bacteria will produce both its own host proteins, and the LHRH protein. A systemic immune response should then be generated to the Brucella suis proteins being produced, allowing for vaccination to Brucella suis. In addition, an immune response would be generated to the LHRH proteins resulting in antibody production and immunocontraception. A broad range of applications can be proposed utilizing the recombinant LHRH, such as other dual vaccines and scale-up production of a low-cost single-injection LHRH vaccine.