"We also tried this for a long time, to isolate viruses in cell cultures. We never succeeded. That's how it is for many labs around the world that have tried. Zhengli Shi is actually the only lab back in Wuhan that managed to do that, to isolate a virus for once.[....] I know Zhengli Shi used the ones in the lab for that as well. Here you have to say, when you do this, practically the first thing that happens with the SARS-2 virus is that this furin site in the virus is destroyed. So when we isolate SARS-2 virus in Vero cells from patients, that furin site goes away immediately because that's a selection disadvantage for the virus in cell culture."