GAMER-Ad: a novel and rapid method for generating recombinant adenoviruses

Oncolytic adenoviruses have become ideal agents in the path toward treating cancer. Such viruses have been engineered to conditionally replicate in malignant cells in which certain signaling pathways have been disrupted. Other than such oncolytic properties, the viruses need to activate the immune system in order to sustain a long-term response. Therefore, oncolytic adenoviruses have been genetically modified to express various immune-stimulatory agents to achieve this. However, genetically modifying adenoviruses is very time consuming and labor intensive with the current available methods. In this paper, we describe a novel method we have called GAMER-Ad to genetically modify adenovirus genomes within 2 days. Our method entails the replacement of the gp19k gene in the E3 region with any given gene of interest (GOI) using Gibson Assembly avoiding the homologous recombination between the shuttle and the parental plasmid. In this manuscript as proof of concept we constructed and characterized three oncolytic adenoviruses expressing CXCL9, CXCL10, and interleukin-15 (IL-15). We demonstrate that our novel method is fast, reliable, and simple compared to other methods. We anticipate that our method will be used in the future to genetically engineer oncolytic but also other adenoviruses used for gene therapy as well.