Tumour heterogeneity is a key hurdle for the effective treatment of cancer using oncolytic viruses (OVs). A better understanding of the pathways involved in delineating tumour cell resistance and hypersensitivity to OVs is critical in order to guide the development of new therapeutic strategies to enhance OVs. In this thesis, I performed a comparative genetic and epigenetic study of the murine OV-resistant colon cancer cell line CT26.WT and its hypersensitive subclone CT26.lacZ. This study led to the identification of retroviral insertion sites in AKAP7 and TP53RK genes, that are potentially involved in conveying sensitivity to infection by OVs and the dysregulation of the interferon antiviral response in the CT26.lacZ cell line. Gene overexpression and gene silencing experiments suggest a functional role of these proteins in controlling viral growth. Further investigation of these genes and their relationship to antiviral response pathways is warranted and may lead to novel strategies for improving the therapeutic activity of OVs.