||Salmonella typhimurium encodes a type III secretion system at Salmonella pathogenicity island I (SPI-1) that work together in the functioning of this macromolecular complex. Previous experiments have shown that a plasmid copy of the SPI-1 is able to direct formation of a biofilm that contains SPI-1 substrate proteins. Development and characterization of this biofilm will lead to important possible applications including engineered biofilm formation, protein antigen presentation, and vaccine delivery. From our experiments, we found that biofilm formation can occur in many different strains of Salmonella , but the removal of the sip genes does not direct biofilm formation. We also investigated the role of S. typhimurium as a vaccine vehicle by inducing cytokine production. The results show some specificity of response to the SipC-OVA peptide, indicating that the system may be useful for delivery of antigens to induce specific immune responses. However, additional experiments will be needed to develop this system.