I thought furin cleavage sites naturally occurred in coronaviruses? See https://www.sciencedirect.com/science/article/pii/S1873506120304165 https://www.scienced

I thought furin cleavage sites naturally occurred in coronaviruses? See https://www.sciencedirect.com/science/article/pii/S1873506120304165 https://www.sciencedirect.com/science/article/pii/S187350612...