Safer retroviral vectors for gene therapy: design, evaluation and validation

Viral vector-based gene therapy can effectively treat and potentially cure genetic disorders. However, the integration of the viral vector in the host-cell genome comes with adverse events, such as clonal expansion due to disregulation of gene expression. Stabile integration of the vector genome is catalysed by the vector-encoded integrase protein (IN). Integration of retroviruses and their derived vectors is not random. Our group identified the cellular proteins (cofactors) that are selected by the viral integrase to tether the integration complex to the chromatin. In addition, we recently showed that for MLV-based vectors, we could uncouple the interaction with the cellular cofactor, without loss of transduction. This project builds on this finding and our expertise to develop retroviral vectors that display a safer integration pattern. We will manipulate integration site choice by redesigning the viral vectors to integrate in safer regions of the genome. We will determine integration sites for these new vectors and evaluate their genotoxicity in vitro in cells and in vivo using a tumor-sensitive mouse-model. Finally, we will investigate whether these safer vectors effectively correct a disease in an X-CGD cell-model.