The present disclosure relates to monoclonal antibodies that bind poly-γ-D-glutamic acid (γDPGA), which is present on the surface of Bacillus anthracis. The disclosure also provides chimeric forms of the monoclonal antibodies, humanized forms of the monoclonal antibodies, and fragments thereof, as well as nucleic acids encoding the antibodies and fragments thereof. Pharmaceutical compositions including such antibodies are also disclosed herein. The disclosure further provides prophylactic, therapeutic, and diagnostic methods of using the disclosed antibodies.