A Recombinant Multivalent Live Vaccine against Bovine Neosporosis and Brucellosis

Bovine neosporosis is an economically important disease of cattle. The disease is caused by Neospora caninum, an intracellular protozoan parasite that is closely related to Toxoplasma gondii. There is no proven vaccine or drugs to prevent or treat N. caninum infections. Preventing and controlling neosporosis through an effective vaccination program would be a highly attractive and economically feasible approach for the cattle industry. Research conducted to date suggest that a Th 1 type of immune response characterized by IFN-Y , but not IL-4 secretion by antigen specific CD4+ T cells, and production of specific IgG2, but not IgG1, antibodies will lead to protection against neosporosis. The overall objective of the proposed research is to develop a recombinant live vaccine that can confer protection to cattle against neosporosis and brucellosis. The company intends to prepare such an effective vaccine by expressing potential protective proteins of N. caninum in Brucella abortus vaccine strain RB51, a bacterial vector with unique adjuvant properties to stimulate a strong Th1 type of immune response. In the Phase I part of the project, the company intends to 1) construct recombinant B. abortus RB51 strains expressing selected potentially protective proteins of N. caninum, and 2) determine the protective ability of the recombinant strains against N. caninum challenge in gerbils.