Many Gram-negative bacterial pathogens possess a type III secretion system that is responsible for injecting proteins into a host cell to subvert normal host cell processes for the benefit of the pathogen – often to promote invasion of the cell. The injection nanomachine is called the type III secretion apparatus (T3SA) and it resembles a syringe embedded in the bacterial membranes with an external needle and needle tip complex that senses target cell contact. The proteins make up the T3SA are highly conserved among closely related bacteria making them the ideal serotype-independent candidates for broadly protective vaccines. We have developed a subunit vaccine by fusing the Shigella T3SA proteins. We have shown it is protective in mice and non-human primates using a variety of routes and adjuvants. Currently, we are using this same platform to develop a broadly protective vaccine against Salmonella.