Susceptibility of I38-substituted viruses to baloxavir acid (BXA) was determined by plaque reduction assay, and fold change (FC) was calculated as relative EC50 of each tested virus to that of the cognate wild-type virus. Bold, clinically confirmed amino acid substitutions.
aData from reference.10
bData obtained from the current study is shown, while FCs of A(H1N1) viruses with I38S and I38L were previously reported as 52- and 9-fold, respectively.25
cThe recombinant PA/I38R viruses were not reverse-genetically rescued.