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. 2018 Jun 5;9(3):e00909-18. doi: 10.1128/mBio.00909-18

TABLE 3 .

Amino acids at key codons in the IAV genome

Host Virus, subtype,
or location
PB2a PA-Xb NAc M2d
Canine CIV-H1N1 E627 Truncated H275 N31
CIV-H3N2 E627 Truncated H275 S31
CIV-H3N8 E627 Truncated H275 S31
Equine EIV H7N7 E627 Complete H275 S31
EIV H3N8 E627 Complete H275 S31
Swine CswH1 K627 Complete/Truncated H275 S31
EAswH1 E627 Complete H275 N31
TRswH3 E627 Truncated H275 S31
PDMswH1 E627 Truncated H275 N31
Human H1N1 (seasonal) K627 Complete H275 (1918–2006) S31
Y275 (2007–2009)
H1N1pdm E627 Truncated H275/Y275 N31
H2N2 K627 Complete H275 S31
H3N2 K627 Complete H275 S31 (1968–2002)
N31 (2003–2017)
Avian Eurasian E627 Complete H275 S31/N31
North American E627 Complete H275 S31
a

The E627K substitution in the PB2 polymerase protein increases replication efficiency in mammals (35).

b

PA-X is a fusion protein that modulates host cellular immune responses (63). The protein is encoded by a +1 frameshift open reading frame (ORF), and a synonymous mutation in the PA gene produces a nonsense mutation at PA-X codon 42 (34).

c

The H274Y substitution (H275Y N1 numbering) in the NA protein is associated with reduced susceptibility to oseltamivir antivirals (64).

d

The S31N substitution in the M2 ion channel protein is associated with reduced susceptibility to adamantane antivirals (65).