Given the role of NK cells in containing disease, in particular targeting tumor cell populations that are refractory to adaptive immune control via MHCI suppression, and reducing postoperative morbidity, we sought to rationally redesign our thymidine kinase (TK)-deleted Lister strain VV, Vaccinia Virus Lister 15 (VVL15)12 to interrupt naturally evolved viral mechanisms of antiviral NK cell suppression with a view to creating a more powerful vector for primary treatment of cancers and additionally optimized as a neoadjuvant therapy. The gene discussed is TKT; the disease is neoplasm.