A polynucleotide sequence is provided, comprising: a nucleic acid sequence having at least 75% identity to SEQ ID NO: 1, wherein said nucleic acid sequence encodes recombinant Bacillus anthracis Protective Antigen (rPA); or a fragment of said nucleic acid sequence wherein said fragment encodes a fragment of recombinant Bacillus anthracis Protective Antigen (rPA). Also provided are expression vectors and host cells comprising the polynucleotide sequence of the invention, and methods for producing rPA or a fragment thereof. The invention further provides antigenic compositions and corresponding methods and uses for inducing an immune response.
1. An isolated polynucleotide comprising the nucleic acid sequence of SEQ ID NO:1, wherein said polynucleotide encodes a recombinant Bacillus anthracis Protective Antigen (rPA).
2. An isolated polynucleotide according to claim 1 , further comprising a polynucleotide encoding a carboxypeptidase G 1 or carboxypeptidase G 2 secretion sequence.
3. An isolated polynucleotide according to claim 1 , further comprising a polynucleotide encoding a secretion sequence for periplasmic translocation of said recombinant Bacillus anthracis Protective Antigen (rPA).
4. An isolated polynucleotide according to claim 1 , further comprising a polynucleotide encoding a secretion sequence for extracellular translocation of said recombinant Bacillus anthracis Protective Antigen (rPA).
5. An isolated polynucleotide according to claim 3 , wherein said secretion sequence is cleavable from said recombinant Bacillus anthracis Protective Antigen (rPA) during periplasmic translocation.
6. An isolated polynucleotide according to claim 4 , wherein said secretion sequence is cleavable from said recombinant Bacillus anthracis Protective Antigen (rPA) during extracellular translocation.
7. An isolated polynucleotide according to claim 2 , wherein the carboxypeptidase G 2 secretion sequence is encoded by the nucleic acid sequence of SEQ ID NO:3.
8. An isolated polynucleotide according to claim 1 , which further comprises a codon encoding a methionine residue at the 5′ end.
9. An isolated polynucleotide according to claim 8 , wherein said polynucleotide comprises the nucleic acid sequence of SEQ ID NO:7.
10. An expression vector comprising the polynucleotide of claim 1 .
11. An expression vector according to claim 10 , further comprising a promoter that is selected so as to ensure that the rPA polypeptide is highly expressed.
12. An expression vector according to claim 11 , wherein said promoter is a malate dehydrogenase (mdh) promoter.
13. An expression vector according to claim 10 further comprising a selectable marker.
14. An expression vector according to claim 10 , wherein said vector expresses the polynucleotide in the absence of a chemical inducer.
15. An expression vector according to claim 11 , wherein the vector is the plasmid pMTL1015, comprising the nucleic acid sequence of SEQ ID NO:4.
16. An expression vector according to claim 11 , wherein the vector is deposited with the ECACC under the accession number 04061401.
17. An isolated host cell grown in vitro, comprising the expression vector according to claim 10 .
18. An isolated host cell according to claim 17 , wherein said host is an E. coli cell.
19. An isolated host cell according to claim 18 , wherein said E. coli cell is E. coli RV308.
20. A kit comprising one or more of: a polynucleotide according to claim 1 ; an expression vector according to claim 10 ; and an isolated host cell according to claim 17 .
21. A vector comprising the nucleic acid sequence of SEQ ID NO:4.
22. The vector deposited with the ECACC under the accession number 04061401.
23. The vector deposited with the ECACC under the accession number 04052501.