The seasonal flu's newfound and widespread drug resistance was made possible by an odd series of mutations -- at least two "permissive" mutations that evolved before the mutation for resistance even occurred, according to a study published this week in Science.
A graphical depiction of the neuraminidase (NA) molecule
with the resistance mutation (H274Y) shown in pink.
The two compensatory mutations (V234M and R222Q)
at the sites shown in orange may help the protein
folding in a way that rescues viral fitness in the
presence of the H274Y mutation.
(The figure was generated using the atomic coordinates
from a crystal structure (PDB ID. 3CL0) on Pymol.)
Image: Kalyan Das (
CABM & Rutgers University, NJ
The results point to a possible method for predicting which strains of flu are more likely to evolve such resistance in the future. "This is a neat story," said structural biologist linkurl:Kalyan Das; of...
J.D. Bloom, et al., "Permissive secondary mutations enable the evolution of influenza oseltamivir resistance," Science, 328:1272-5, 2010.

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