Attenuated
The present invention relates to vaccines, in particular, to an attenuated gram-negative cell comprising the SPI2 gene locus, wherein at least one gene of the SPI2 locus is inactivated, wherein said inactivation results in an attenuation/reduction of virulence compared to the wild type of said cell, and to a carrier for the presentation of an antigen to a host, which carrier is said attenuated gram-negative cell, wherein said cell comprises at least one heterologous nucleic acid molecule comprising a nucleic acid sequence coding for said antigen, wherein said cell is capable of expressing said nucleic acid molecule or capable of causing the expression of said nucleic acid molecule in a target cell.
1. An isolated attenuated gram-negative Salmonella cell comprising the SPI2 gene locus, wherein at least one effector (sse) gene selected from the group consisting of sseC, sseD and sseE of the SPI2 locus is inactivated, wherein said inactivation results in an attenuation/reduction of virulence compared to the wild type of said cell.
2. The isolated attenuated gram-negative Salmonella cell according to claim 1 , wherein said cell has a broad host range.
3. The isolated attenuated gram-negative Salmonella cell according to claim 2 , wherein said cell is a Salmonella serotype Typhimurium Definitive Type 104 (DT104) cell.
4. The isolated attenuated gram-negative Salmonella cell according to claim 1 , wherein at least one gene is inactivated by a mutation comprising a deletion.
5. The isolated attenuated gram-negative Salmonella cell according to claim 4 , wherein said deletion comprises at least 6 nucleotides.
6. The isolated attenuated gram-negative Salmonella cell according to claim 4 , wherein the mutation comprises a deletion of the complete coding sequence for said gene.
7. The isolated attenuated gram-negative Salmonella cell according to claim 1 , wherein at least one gene is inactivated by a mutation comprising the insertion of a heterologous nucleic acid molecule.
8. The isolated attenuated gram-negative Salmonella cell according to claim 7 , wherein said mutation is a non-polar mutation.
9. The isolated attenuated gram-negative Salmonella cell according to claim 1 , wherein at least one additional gene located outside of the SPI2 locus is inactivated, wherein the inactivation results in a further attenuation/reduction of virulence compared to the wild type.
10. The isolated attenuated gram-negative Salmonella cell according to claim 9 , wherein said additional gene is superoxide dismutase.
11. The isolated attenuated gram-negative Salmonella cell according to claim 1 , comprising at least one selective marker cassette.
12. The isolated attenuated gram-negative Salmonella cell according to claim 11 , wherein said selective marker cassette is capable of conferring an antibiotic resistance to the cell.
13. The isolated attenuated gram-negative Salmonella cell according to claim 1 comprising at least one gene expression cassette.
14. The isolated attenuated gram-negative Salmonella cell according to claim 1 comprising at least one transactivator cassette.
15. The isolated attenuated gram-negative Salmonella cell according to claim 1 comprising at least one invertase cassette.
16. The isolated attenuated gram-negative Salmonella cell according to claim 1 further comprising at least one insertion cassette.