The invention is based on the discovery of the epitope in the Stx2 protein for the 11 E1O antibody. The invention features compositions containing non-full length Stx2 polypeptides that include the 11 E1O monoclonal antibody epitope. The invention also features methods of producing anti-Stx2 antibodies specific for the 11 E1O epitope of the Stx2 protein. Additionally, the invention features methods for treating a subject having, or at risk of developing, a Shiga toxin associated disease (e.g., hemolytic uremia syndrome and diseases associated with E. coli and S. dysenteriae infection) with a polypeptide that includes the 11 E1O epitope or with an anti-Stx2 antibody developed using the methods of the invention. Furthermore, the invention features the detection of Stx2 in a sample using the antibodies developed using the methods of the invention.