Retroviral bicistronic vectors.

The co-expression of genes can greatly enhance the efficiency and versatility of gene therapy applications. A variety of options exists to simultaneously express two genes in genetically modified cells. The most common approach relies on bicistronic vectors in which the genes are linked to each other by an internal ribosome entry site allowing co-translational expression of both cistrons. This review gives an overview of gene vector systems currently in use for coordinated expression of transgenes with particular focus on retroviral bicistronic vectors. The structural and functional characteristics of bicistronic vectors are discussed as well as factors influencing their efficiency such as the nature of the transgenes and the cell types in which they are expressed. Finally, the potential for clinical applications of retroviral bicistronic vectors in molecular genetics is highlighted.