Described herein is a method of identifying a monoclonal antibody (or antigen-binding fragment thereof) that specifically binds a plurality of lyssaviruses for use in post-exposure rabies prophylaxis or in the treatment of clinical rabies. The method includes using a naïve antibody phage display library to screen for phage clones that bind whole recombinant rabies virus or cells expressing glycoprotein from multiple lyssaviruses (such as RABV, MOKV and WCBV) and/or specifically bind recombinant glycoprotein from different lyssaviruses.