In this Phase I proposal, the Offeror proposes to develop a large panel of monoclonal antibodies (mAbs), including antibodies for identifying and tracking various types of immune cells and antibodies against different IgG subtypes and Fc gamma receptors in S. hispidus (Catton rat). The affinity of the mAbs will be determined by Bio-Layer Interferometry (BLI), and the binding specificity will be evaluated by flow cytometry, ELISA, and Western blot using primary cells from cotton rats and knock-in cells as well as a competition assay using recombinant proteins. Successful completion of this project will provide a set of high-affinity antigen-specific antibodies to the cotton rat research community for studying immune responses in Catton rat models of infectious diseases.