Direct IgG epitope mapping on bacterial AB toxins by cryo-EM.

This cryo-EM protocol was used to determine the B cell epitope map on the CdtB subunit of typhoid toxin, an A2B5 toxin secreted by Salmonella Typhi during infection. Immunoglobulin G (IgG) was directly mixed with typhoid toxin in this protocol, different from our previous cryo-EM protocol that uses the Fab fragments in place of IgG. This simple approach requires smaller amounts of materials, supporting the broader use of this protocol for determining antibody recognition sites on various antigens. For complete details on the use and execution of this protocol, please refer to Ahn et al. (2021) and Nguyen et al. (2021).