H9N2 influenza virus acquires intravenous pathogenicity on the introduction of a pair of di-basic amino acid residues at the cleavage site of the hemagglutinin and consecutive passages in chickens

https://t.co/xn3DWUbsOR Guess what happen if they first tried substitution with the protease cleavage site, but then the Spike did not show evidence of cleavage and that they determined that a substitutive methodology does not guarantee cleavage of all CoV

46/ There are precedents for passaging engineered coronaviruses https://t.co/Ixl1bGE2LY However, they are considerably less sophisticated than would be required in this case. This would seem to require immune competence, ACE2 humanisation, lungs and a long

46/ There are scary precedents for passaging engineered viruses https://t.co/Ixl1bGE2LY However, they are considerably less sophisticated than would be required in this case. This would seem to require immune competence, ACE2 humanisation, lungs and a long