Result: Only six coding substitutions were observed within the
HA receptor-binding site (RBS): one
A186T variant in the 190-helix (184-191); and 5 residue 222 variants (
D222E and
D222G) in the 220-loop (mature peptide residues 218-225).
Result: When analysis of positive selection was conducted, only two viral sites located in
HA (namely
D222G/E and
E374K) displayed evidence of adaptive evolution, corresponding to the
HA RBS and
HA2-subunit position 47, respectively.
Discussion: And despite the fact that A/H1N1pdm
HA D222E/G (and N) variant viruses have been detected in fatal cases,