Stable and long-lasting siRNA expression vectors and the applications thereof

An siRNA expression vector capable of inhibiting or extinguishing the expression of a target gene in a mammalian cell, which vector is characterized in that it comprises:

• (1) a bacterial cassette comprising a bacterial origin of replication and a bacterial selectable marker M1,
• (2) a cassette for selection in eukaryotic cells comprising a selectable marker M2 for eukaryotic cells, and in particular for mammalian cells, under the control of an appropriate promoter,
• (3) an EBV cassette comprising at least one fragment of the Epstein-Barr virus nuclear antigen 1 (EBNA-1), at least one fragment of the family of repeats (FR) and at least one fragment of the double symmetry (DYAD) region, and
• (4) an siRNA transcription cassette comprising at least one region encoding an siRNA corresponding to the target gene to be inhibited or to be extinguished, under the control of regulatory elements for transcription in mammalian cells, which regulatory elements include at least one promoter capable of transcribing an siRNA in mammalian cells and a transcription terminator;
• wherein said siRNA transcription cassette is immediately downstream of the transcription initiation site or else a maximum of at most 20 base pairs away from the latter;
• said transcription initiation site being CCG and said siRNA transcription cassette comprising, downstream of the sequence encoding the siRNA, a transcription terminator which comprises a sequence of 6 consecutive thymidines, in the sense strand of the construct.