Abstract: The present invention relates to improved retroviral vectors. In particular, the present invention relates to retroviral vectors that retain introns in genes of interest during vector production. The present invention further provides host cells and animals comprising gene delivered by the vectors. The present invention additionally provides methods of using such retroviral vectors, host cells and animals in research, diagnostic and therapeutic applications.

Abstract: Inducible gene expression systems and a method thereof. A first inducible gene expression system includes a first vector comprising at least one retroviral promoter and at least one factor to induce the retroviral promoter. At least one gene product is expressed in proportion to retroviral promoter induction. The method includes providing a first vector comprising at least one retroviral promoter and providing at least one factor corresponding to the retroviral promoter. The retroviral promoter is induced with the at least one factor. At least one protein is expressed based on the induction of the retroviral promoter. A second inducing expression system includes first vector means comprising at least one retroviral promoter, means for inducing the retroviral promoter, and means for expressing at least one protein based on the induction of the retroviral promoter.