Hello,

I have a project on SARS-COV2 pseudoviruses. I use p8.91 and pCSFLW plasmids to produce the pseudo, but I find something strange. When I prepare both the plasmids in parallel starting from glycerol stock ( same bacteria strain, same plasmid preparation kit, same ON growth), the backbone (p8.91) has the lowest amount extracted (even if present, by RE digestion), and it does not work (no infectious pseudo). But if I transform bacteria again, at the first extraction, the pseudos are actually infectious. I can't figure out why. (I could just transform every time, but I takes a day more).

Does anybody have the same problem? Thank you.