Targeted transduction of the Herpes Simplex virus thymidine kinase gene is toxic in vitro and in vivo , in the presence of ganciclovir. A) MIAPACA2 cells stably expressing the tdTomato protein were transduced with viruses packaged into broad tropism envelopes, expressing either the GFP protein (CT, dark gray line) or a bicistronic gene encoding the firefly luciferase and the herpes simplex virus thymidine kinase (LUC-TK, light gray line). Cells were treated with ganciclovir. Cell death was examined 10 days after treatment. Cell viability was measured by MTS tests. ***: p<0.001 in Student’s t test compared to control condition. B) TdTomato-MIAPACA2 cells were grafted in the pancreas of recipient mice. After 21 days anti-MUC4-conjugated viruses (MUC4) or control IgGs-conjugated viruses (ISO) were injected in the intra-pancreatic tumors (n=6 animals in each group). After 36 days, ganciclovir was injected daily for two weeks (solid red lines). Left panels: fluorescence corresponding to grafted tumor cells the first day of GCV injection (Day 36) and one week after the beginning of GCV injections (Day 45). Right chart: Quantification of fluorescence signals expressed as a fold increase of fluorescence detected on day 1. C) Left panels: luminescence signals observed in mice the first day of GCV injection (Day 36) and one week after the beginning of GCV injections (Day 45). Right chart: Raw luminescence signals are reported as ph/sr/s from the day of virus injection (day 21) to the day of experiment termination (day 45). On day 21, when viruses were injected, we had lost 1 mouse in the MUC4 group and 2 mice in the ISO group. On day 45, we had only 3 mice in each group. p=0.06 with a 2-sided Mann Whitney test against control signal, n=3. * p=0.018 with a 2-sided Mann Whitney test against control signal, n=4-5.