The disclosure provides antibody agents that bind to a programmed death-1 (PD-1) protein. Particular immunoglobulin heavy chain polypeptide and immunoglobulin light chain polypeptide sequences are explicitly provided. Also provided are related nucleic acids, vectors, compositions, and methods of using the anti-PD-1 antibody agent to treat a disorder or disease that is responsive to PD-1 inhibition, such as cancer or an infectious disease.