. 2020 Oct 24;15(3):389–395. doi: 10.1111/irv.12821

Table 1.

Susceptibility of the recombinant viruses with PA I38 substitutions to baloxavir acid

Amino acid substitution in PA subunit		FC of BXA
Amino acid substitution in PA subunit		rgA/WSN/33 (H1N1)	rgA/Victoria/3/75 (H3N2)
Treatment‐emergent substitutions	I38T	27.24 ^a	56.59 ^a
	I38F	10.61 ^a	20.13 ^a
	I38M	13.15 ^a	13.77 ^a
	I38N	23.66	10.32
	I38S	12.43 ^b	5.85
	I38R	Not rescued ^c	Not rescued ^c
Polymorphic substitutions	I38V	2.18	1.83
Polymorphic substitutions	I38L	6.33 ^b	2.17

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.

^{^a}

Data from reference. ¹¹

^{^b}

Data obtained from the current study are shown, while FCs of A(H1N1)pdm09 viruses with I38S and I38L were previously reported as 52‐ and 9‐fold, respectively. ²⁶

^{^c}

The recombinant PA/I38R viruses were not reverse‐genetically rescued.