Adenovirus vectors for manipulating human immune cells

Natural Killer (NK) cell mediated immune surveillance is important in preventing and controlling malignancies. However, tumours ultimately evade NK cells, enhancing their survival and progression. The immunosuppressive cytokine TGF-β is an established, potent inhibitor of NK cell mediated anti-tumour immunity. Genetically manipulating NK cells to resist the actions of TGF-β is a potential route by which to enhance NK cell-mediated immunotherapy. However, NK cells are notoriously difficult to manipulate with conventional viral vectors or transfection techniques and alternative methodologies are required to achieve this. I have explored the ability of several virus vectors to transduce primary human NK cells, with a chimaeric adenovirus (Ad) vector proving the most promising. Replacing the Ad5 fibre with that from Ad35 (forming Ad5f35) generated a vector capable of efficient transduction of primary human NK cells and the NK cell lines, YT, NKL and NK92. Ad5F35 utilises CD46 as an entry receptor and NK cell transduction by Ad5f35 was CD46 dependent. The Ad5f35 vector provides a route to genetically manipulate NK cells. Transfection experiments in non-lymphoid cells showed that expression of a dominant negative TGF-β receptor II or inhibitory SMADs (SMAD7) inhibit the TGF-β signalling pathway. Using recombination-based methods in E.coli, an Ad5f35 vector was constructed to deliver the dominant negative TGF-β receptor II into mammalian cells. High expression and inhibitory activity was achieved in non-lymphoid cells, but expression in NK cells was low and activity reduced. Nevertheless, the Ad5f35 system clearly has potential for future applications in NK cells, including the development of NK cell based cellular therapies.