Abstract: The present invention provides a vector system comprising a mutated post-transcriptional regulatory element. In particular, the present invention relates to a mutated WPRE sequence that can efficiently express nucleotides of interest in a retroviral vector system. The present invention also relates to methods of delivering and expressing nucleotides of interest to a target cell.

Abstract: The present invention provides a vector system comprising a mutated post-transcriptional regulatory element. In particular, the present invention relates to a mutated WPRE sequence that can efficiently express nucleotides of interest in a retroviral vector system. The present invention also relates to methods of delivering and expressing nucleotides of interest to a target cell.

Abstract: Provided is an improved method for controlling gene expression in vivo through the use of a gene switch comprising one or more aptamer sequences operably linked to or incorporated into the untranslated regions (UTRs) of a transgene or nucleotide sequence of interest. Also provided are expression vectors having aptamer sequences located within the 3? UTR, the 5? UTR and between the genes of a multicistronic mRNA, as well as methods of using the expression vectors for controlling or regulating gene expression.

Abstract: A selection system suitable for use in vivo is provided, the system comprising: I) a plurality of first nucleotide sequences encoding a gene product capable of binding to and effecting the cleavage, directly or indirectly, of a nucleotide sequence, or a transcription product thereof; wherein a region of the first nucleotide sequence required for binding to the nucleotide sequence is heterogeneous within the plurality of first nucleotide sequences; and ii) a second nucleotide sequence comprising: (a) a coding region encoding a detectable marker operably linked to sequences required for mRNA stability and/or translation; and (b) a third nucleotide sequence positioned between the coding region and at least one of the sequences required for mRNA stability and/or translation; wherein (a) and (b) are operably linked to a regulatory sequence capable of directing expression of (a) and (b) as a contiguous RNA molecule in a host cell; and wherein the first nucleotide sequence encoding a gene product is capable of bindi

Abstract: The present invention provides a vector system comprising a mutated post-transcriptional regulatory element. In particular, the present invention relates to a mutated WPRE sequence that can efficiently express nucleotides of interest in a retroviral vector system. The present invention also relates to methods of delivering and expressing nucleotides of interest to a target cell.

Abstract: A selection system suitable for use in vivo is provided, the system comprising: I) a plurality of first nucleotide sequences encoding a gene product capable of binding to and effecting the cleavage, directly or indirectly, of a nucleotide sequence, or a transcription product thereof; wherein a region of the first nucleotide sequence required for binding to the nucleotide sequence is heterogeneous within the plurality of first nucleotide sequences; and ii) a second nucleotide sequence comprising: (a) a coding region encoding a detectable marker operably linked to sequences required for mRNA stability and/or translation; and (b) a third nucleotide sequence positioned between the coding region and at least one of the sequences required for mRNA stability and/or translation; wherein (a) and (b) are operably linked to a regulatory sequence capable of directing expression of (a) and (b) as a contiguous RNA molecule in a host cell; and wherein the first nucleotide sequence encoding a gene product is capable of bindi