Ferret CXCL13 (C-X-C motif chemokine ligand 13), also known as BCA-1 (B-cell–attracting chemokine 1), is a homeostatic chemokine belonging to the CXC chemokine family that plays a key role in B-cell migration and organization of lymphoid tissues. In ferrets (Mustela putorius furo), CXCL13 is produced primarily by follicular dendritic cells, stromal cells, and macrophages within secondary lymphoid organs, including the lymph nodes, spleen, and mucosal-associated lymphoid tissues. CXCL13 signals through the chemokine receptor CXCR5, which is expressed on B lymphocytes and T follicular helper (Tfh) cells, directing their migration into lymphoid follicles and germinal centers where antibody responses are generated. In ferret immune responses, CXCL13 contributes to B-cell homing, germinal center formation, and development of humoral immunity during infection or vaccination. Because ferrets are widely used as animal models for respiratory viral diseases, including influenza virus and SARS-CoV-2 infection, CXCL13 has been studied in the context of lymphoid tissue activation and antibody responses in the respiratory tract, where B-cell recruitment and germinal center reactions are important for protective immunity and vaccine evaluation.