Fig. 4: Protect, modify, deprotect (PMD).
a A general schematic of the PMD strategy. First, the epitope is protected by the target Ab (shown in red). Then the surfaces of the protein complex are modified by PEG to render them non-immunogenic (shown in grey). Finally, the epitope is deprotected by the removal of the Ab. b Iterative antigen engineering is required to successively increase the resolution of epitope masking. Holes represent insufficiently masked regions of the antigen and can be characterized using binding experiments with a panel of known off-target antibodies.
