2011 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 The primary goal of this project is to continue to select adjuvants that can maximize the host immune responses against Neospora antigens. The Neospora cyclophilin (NcCyP) was selected to be the vaccine candidate for this project. This protein was highly expressed in E. coli in a soluble form. Experiments were conducted to characterize the two potent adjuvants identified in previous studies. The results showed that NcCyP stimulated production of interferon-gamma (an inflammatory cytokine) and lymphocyte proliferation only in animals vaccinated with a formulation comprised of NcCyP and one of the two potent adjuvants. These studies confirmed the efficacy of the Pfizer adjuvants which will be used in a vaccine trial in the small ruminant neosporosis model.