The Genesis and Spread of Reassortment Human Influenza A/H3N2 Viruses Conferring Adamantane Resistance

Lone Simonsen, Cecile Viboud, Bryan T. Grenfell, Jonathan Dushoff, Lance Jennings, Marita Smit, Catherine Macken, Mami Hata, Julia Gog, Mark Miller, Edward C. Holmes*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

A dramatic rise in the frequency of resistance to adamantane drugs by influenza A (H3N2) viruses has occurred in recent years -- from approximately 2% to approximately 90% in multiple countries worldwide-and associated with a single S31N amino acid replacement in the viral matrix M2 protein. To explore the emergence and spread of these adamantane resistant viruses we performed a phylogenetic analysis of recently sampled complete A/H3N2 genome sequences. Strikingly, all adamantane resistant viruses belonged to a single lineage (the "N-lineage") characterized by 17 amino acid replacements across the viral genome. Further, our analysis revealed that the genesis of the N-lineage was due to a 4+4 segment reassortment event involving 2 distinct lineages of influenza A/H3N2 virus. A subsequent study of hemagglutinin HA1 sequences suggested that the N-lineage was circulating widely in Asia during 2005, and then dominated the Northern hemisphere 2005-2006 season in Japan and the USA. Given the infrequent use of adamantane drugs in many countries, as well as the decades of use in the US associated with little drug resistance, we propose that the globally increasing frequency of adamantane resistance is more likely attributable to its interaction with fitness-enhancing mutations at other genomic sites rather than to direct drug selection pressure. This implies that adamantanes may not be useful for treatment and prophylaxis against influenza viruses in the long term. More generally, these findings illustrate that drug selection pressure is not the sole factor determining the evolution and maintenance of drug resistance in human pathogens.
Original languageEnglish
JournalMolecular Biology and Evolution
Volume24
Issue number8
Pages (from-to)1811-1820
ISSN0737-4038
DOIs
Publication statusPublished - 2007
Externally publishedYes

Bibliographical note

This article has been found as a ’Free Version’ from the Publisher on June 26 2020. When access to the article closes, please notify [email protected]

Keywords

  • influenza virus
  • Adamantane resistance
  • Reassortment
  • hitch-hiking
  • natural selection

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