2009 Annual Report 1a.Objectives (from AD-416) To evaluate vaccine adjuvants using Neospora caninum antigens in the mouse model of neosporosis. 1b.Approach (from AD-416) Neospora caninum antigens will be formulated with Pfizer adjuvants and used to immunize the mouse model (BALB/C) of neosporosis. Humoral (antibody respons) and cell-mediated immunities (T cell and cytokine response) of the immunized mice will be determined in vitro. 3.Progress Report This agreement is to study the effects of adjuvants formulated with Neospora candidate vaccines. A number of Neospora vaccine candidates have been identified and characterized. However, for the best protective efficacy, these candidate vaccines will have to be evaluated in combination with improved adjuvants provided by Pfizer, Inc. Recombinant Neospora vaccines have been expressed in E. coli and purified by affinity chromatography. The impurity of the purified recombinant proteins was determined by a host cell protein assay (assessing the level of contaminating bacterial proteins) and an endotoxin assay. A total of 12 adjuvants have been selected based on their ability to stimulate a type 1 immune response, favoring a protective immunity. Vaccine trials evaluating these formulations using the murine neosporosis model are planned.