To mimic the conditions of short-term treatment, we decided to use the inducible doxycycline-dependent Tet-On expression system, which allows regulated expression of the protein of interest [55] . To determine whether treatment of cells with doxycycline interferes with viral replication, we cultivated VSVDG/LASVGPinfected CHO-K1 Tet-On cells in the presence or absence of doxycycline (1 mg/ml) for 24 h and 48 h, respectively. As shown in Fig. 1B , CHO-K1 Tet-On cells treated with doxycycline produced a virus titer comparable to cells that were cultivated in the absence of doxycycline, indicating that these conditions used in our experiments have no influence on efficient virus replication.