HSV as A Platform for the Generation of Retargeted, Armed, and Reporter-Expressing Oncolytic Viruses

Previously, we engineered oncolytic herpes simplex viruses (o-HSVs) retargeted to the HER2 (epidermal growth factor receptor 2) tumor cell specific receptor by the insertion of a single chain antibody (scFv) to HER2 in gD, gH, or gB. Here, the insertion of scFvs to three additional cancer targets-EGFR (epidermal growth factor receptor), EGFRvIII, and PSMA (prostate specific membrane antigen)-in gD Delta 6-38 enabled the generation of specifically retargeted o-HSVs. Viable recombinants resulted from the insertion of an scFv in place of aa 6-38, but not in place of aa 61-218. Hence, only the gD N-terminus accepted all tested scFv inserts. Additionally, the insertion of mIL12 in the US1-US2 intergenic region of the HER2-or EGFRvIII-retargeted o-HSVs, and the further insertion of Gaussia Luciferase, gave rise to viable recombinants capable of secreting the cytokine and the reporter. Lastly, we engineered two known mutations in gB; they increased the ability of an HER2-retargeted recombinant to spread among murine cells. Altogether, current data show that the o-HSV carrying the aa 6-38 deletion in gD serves as a platform for the specific retargeting of o-HSV tropism to a number of human cancer targets, and the retargeted o-HSVs serve as simultaneous vectors for two molecules.