Schematic representation of the recombinant autodisplay system pAIDA1. A) The surface display plasmid pAIDA1 based on the AIDA-I autotransporter. Expression is under control of the lacUV5 promoter, and two detection/affinity tags (His6 and c-Myc), in addition to two different protease cleavage recognition sites (3C and TEV), flank the passenger protein, which in this study is represented by various Salmonella antigens. SP represents the signal peptide, which is cleaved off upon translocation over the inner membrane, while L is the endogenous linker region of AIDA-I (consisting of the first 54 amino acids of the native passenger). The plasmid carries a p15A origin of replication and a chloramphenicol resistance gene (CmlR). B) Outer membrane (OM) including the surface displayed recombinant protein (mature) expressed from pAIDA1.