Further improved AAV vectors produced in insect cells
The present invention relates to the production of adeno-associated viral vectors in insect cells. The insect cells therefore comprise a first nucleotide sequence encoding the adeno-associated virus (AAV) capsid proteins, whereby the initiation codon for translation of the AAV VP1 capsid protein is a non-ATG, suboptimal initiation codon and wherein the coding sequence for one or more amino acid residues have been inserted between the suboptimal translation initiation codon and the codon encoding the amino acid residue that corresponds to the amino acid residue at position 2 of the wild type capsid amino acid sequence of which the first amino acid residue is alanine, glycine valine, aspartic acid or glutamic acid. The insect cell further comprises a second nucleotide sequence comprising at least one AAV inverted terminal repeat (ITR) nucleotide sequence; a third nucleotide sequence comprising a Rep52 or a Rep40 coding sequence operably linked to expression control sequences for expression in an insect cell; and, a fourth nucleotide sequence comprising a Rep78 or a Rep68 coding sequence operably linked to expression control sequences for expression in an insect cell. The invention further relates to adeno-associated viral vectors with an altered ratio of the viral capsid proteins.
1. A nucleic acid molecule comprising a first nucleotide sequence comprising an open reading frame (ORF), wherein the ORF in 5′ to 3′ order comprises: (i) a suboptimal translation initiation codon consisting of CTG or ACG; (ii) an inserted codon encoding alanine; and (iii) a sequence encoding a wild-type adeno-associated virus (AAV) serotype 5 capsid protein VP1 starting at position 2 of the protein and lacking the wild-type translation initiation codon.
2. The nucleic acid molecule according to claim 1 , wherein the capsid proteins have the amino acid sequence of SEQ ID NO; 22.
3. The nucleic acid molecule according to claim 1 , wherein the inserted codon encoding an amino acid residue is selected from the group consisting of GCT, GCC, GCA and GCG.
4. The nucleic acid molecule according to claim 3 , wherein the inserted codon encoding an amino acid residue is GCT.
5. A first nucleic acid construct comprising the nucleic acid molecule according to claim 1 , wherein the first nucleotide sequence encoding the AAV capsid proteins is operably linked to an expression control sequence for expression in an insect cell.
6. The nucleic acid construct according to claim 5 , wherein the nucleotide sequence of the ORF is operably linked to a promoter selected from the group consisting of polyhedron promoter, p10 promoter, Hsp27 EcRE+minimal Hsp70 promoter, deltaE1 promoter and E1 promoter.
7. The nucleic acid construct according to claim 5 , wherein the construct is an insect-compatible vector.
8. The nucleic acid construct according to claim 7 , wherein the vector is a baculoviral vector.
9. The nucleic acid construct according to claim 5 , wherein the nucleic acid molecule comprises an ORF selected from the group consisting of: SEQ ID NO:51, SEQ ID NO:69, SEQ ID NO:42, SEQ ID NO:47 and SEQ ID NO:48.
10. The nucleic acid construct according to claim 9 , wherein the ORF is SEQ ID NO:51.
11. An insect cell comprising the first nucleic acid construct according to claim 5 .
12. The insect cell according to claim 11 , wherein the insect cell further comprises: (a) a second nucleotide sequence comprising at least one AAV inverted terminal repeat (ITR) nucleotide sequence; (b) a third nucleotide sequence comprising a Rep78 or a Rep68 coding sequence operably linked to an expression control sequence for expression in an insect cell.
13. The insect cell according to claim 12 , wherein the second nucleotide sequence further comprises at least one nucleotide sequence that encodes a gene product of interest for expression in a mammalian cell.
14. The insect cell according to claim 13 , wherein the second nucleotide sequence comprising said at least one nucleotide sequence encoding said gene product of interest comprises two AAV ITR nucleotide sequences between which the sequence encoding the gene product of interest is located.
15. An AAV virion comprising a VP1 capsid protein and comprising in its genome at least one nucleotide sequence encoding a gene product of interest, wherein: (a) the at least one nucleotide sequence encoding the gene product of interest is not a native AAV nucleotide sequence, (b) the AAV VP1 capsid protein comprises, from N terminus to C terminus: (i) a first amino acid residue encoded by a translation initiation codon consisting of CTG or ACG; (ii) an inserted alanine residue; (iii) an amino acid sequence of an AAV serotype 5 VP1 capsid protein starting at position 2 of the protein and lacking the amino acid residue that is encoded by the VP1 translation initiation codon.
16. The AAV virion according to claim 15 , wherein the gene product of interest encodes a Factor IX or a Factor VIII protein.
17. The AAV virion according to claim 16 , wherein the Factor IX or Factor VIII protein is a human Factor IX or Factor VIII protein.
18. A method for producing AAV virions in an insect cell, comprising the steps of: (a) culturing the insect cell of claim 11 under conditions such that AAV virions are produced; and (b) optionally recovering the AAV virions.
19. The insect cell according to claim 12 , wherein the insect cell further comprises a fourth nucleotide sequence comprising a Rep52 or Rep40 coding sequence operably linked to an expression control sequence for expression in an insect cell.
20. The insect cell according to claim 19 , wherein the first nucleic acid construct comprises the third and fourth nucleotide sequences; and the insect cell further comprises a second nucleic acid construct comprising the second nucleotide sequence.
21. The insect cell according to claim 20 , wherein the second nucleic construct is a baculoviral vector.