Avirulent strains of Salmonella typhimurium are being considered as an
tigen delivery vectors. During its intracellular stage in the host, S.
typhimurium resides within a membrane-bound compartment and is not an
efficient inducer of class I-restricted immune responses. Viral epito
pes were successfully delivered to the host-cell cytosol by using the
type III protein secretion system of S. typhimurium. This resulted in
class I-restricted immune responses that protected vaccinated animals
against lethal infection. This approach may allow the efficient use of
S. typhimurium as an antigen delivery system to control infections by
pathogens that require this type of immune response for protection.