Technical Abstract: A major obstacle to advances in veterinary immunology and disease control is the lack of sufficient immunological reagents specific for ruminants, swine, poultry, equine and aquaculture species". Sets of reagents, i.e., monoclonal (mAb) and polyclonal antibodies, that can identify the major leukocyte subsets (T and B lymphocytes, NK cells, macrophages, dendritic cells, neutrophils) are needed to evaluate changes during disease and following vaccination and to give scientists the ability to manipulate these cell populations in order to evaluate their roles in protective immunity as well as in immunopathology. Development of the above reagents will address the USDA/NRI goal of enhancing the safety of the Nation's agriculture and food supply by aiding in the development of vaccines. This proposal presents a broad community plan to begin to systematically address the immunological reagent gap for the US veterinary immunology research community including for the following groups: ruminants (concentrating on cattle), swine, poultry (primarily chickens with some evaluation of reagents on turkey cells), horses and aquaculture species (concentrating on channel catfish and salmonid trout, two of the principal economically important species) with a goal of 20 reagents per species group.