As for the stability of the bioengineered viruses, we passed viruses through MARC-145 cells and PAMs for 5-6 generations. Authentic progeny viruses were rescued after three generations, but viruses with a titer higher than 10 3 were only rescued with the indicator protein expressing group and the one expressing IFNδ3. DsRed-and IFNδ3-expressing viruses remained stable for 6 generations (Data not shown). 