Attenuated Salmonella enterica serovar paratyphi a and uses thereof

An attenuated Salmonella Paratyphi A strain, wherein said strain has a deletion mutation in the guaBA locus, and a deletion mutation in the clpX gene, wherein said deletion mutation in the guaBA locus is a deletion mutation in the guaB gene, a deletion mutation in the guaA gene, or a deletion mutation in both guaB and guaA genes.