Permissive secondary mutations enable the evolution of influenza oseltamivir resistance
The His274→ Tyr274 (H274Y) mutation confers oseltamivir resistance on N1 influenza
neuraminidase but had long been thought to compromise viral fitness. However, beginning
in 2007–2008, viruses containing H274Y rapidly became predominant among human
seasonal H1N1 isolates. We show that H274Y decreases the amount of neuraminidase that
reaches the cell surface and that this defect can be counteracted by secondary mutations
that also restore viral fitness. Two such mutations occurred in seasonal H1N1 shortly before …
neuraminidase but had long been thought to compromise viral fitness. However, beginning
in 2007–2008, viruses containing H274Y rapidly became predominant among human
seasonal H1N1 isolates. We show that H274Y decreases the amount of neuraminidase that
reaches the cell surface and that this defect can be counteracted by secondary mutations
that also restore viral fitness. Two such mutations occurred in seasonal H1N1 shortly before …
The His274→Tyr274 (H274Y) mutation confers oseltamivir resistance on N1 influenza neuraminidase but had long been thought to compromise viral fitness. However, beginning in 2007–2008, viruses containing H274Y rapidly became predominant among human seasonal H1N1 isolates. We show that H274Y decreases the amount of neuraminidase that reaches the cell surface and that this defect can be counteracted by secondary mutations that also restore viral fitness. Two such mutations occurred in seasonal H1N1 shortly before the widespread appearance of H274Y. The evolution of oseltamivir resistance was therefore enabled by “permissive” mutations that allowed the virus to tolerate subsequent occurrences of H274Y. An understanding of this process may provide a basis for predicting the evolution of oseltamivir resistance in other influenza strains.
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