Giuseppe
Emeritus
[Source: PLoS ONE, full text: (LINK). Abstract, edited.]
Genetic Structure of Human A/H1N1 and A/H3N2 Influenza Virus on Corsica Island: Phylogenetic Analysis and Vaccine Strain Match, 2006?2010
Alessandra Falchi<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP><SUP>,</SUP><SUP>3</SUP><SUP>,</SUP><SUP>4</SUP><SUP>*</SUP>, Jean Pierre Amoros<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP><SUP>,</SUP><SUP>3</SUP>, Christophe Arena<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP><SUP>,</SUP><SUP>3</SUP><SUP>,</SUP><SUP>4</SUP>, Jean Arrighi<SUP>4</SUP>, Fran?ois Casabianca<SUP>5</SUP>, Laurent Andreoletti<SUP>6</SUP><SUP>,</SUP><SUP>7</SUP>, Cl?ment Turbelin<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Antoine Flahault<SUP>8</SUP>, Thierry Blanchon<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Thomas Hanslik<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Laurent Varesi<SUP>3</SUP>
1 INSERM, UMR-S 707, F-75012, Paris, France, 2 University Pierre and Marie Curie, Universit? Paris 06, UMR-S U707, F-75012, Paris, France, 3 Laboratory of Virology, University of Corsica, Corsica, France, 4 Observatoire R?gionale de la Sant?, Ajaccio, France, 5 Institut national de la Recherche Agronomique, Corte, France, 6 Unit? de Virologie M?dicale et Mol?culaire, Centre Hospitalier Universitaire, Reims, France, 7 IFR 53/EA-4303 (DAT/PPCIDH), Facult? de M?decine, Reims, France, 8 EHESP School of Public Health, Rennes, France
Abstract
Background
The aim of this study was to analyse the genetic patterns of Hemagglutinin (HA) genes of influenza A strains circulating on Corsica Island during the 2006?2009 epidemic seasons and the 2009?2010 pandemic season.
Methods
Nasopharyngeal samples from 371 patients with influenza-like illness (ILI) were collected by General Practitioners (GPs) of the Sentinelles Network through a randomised selection routine.
Results
Phylogenetic analysis of HA revealed that A/H3N2 strains circulating on Corsica were closely related to the WHO recommended vaccine strains in each analyzed season (2006?2007 to 2008?2009). Seasonal Corsican influenza A/H1N1 isolated during the 2007?2008 season had drifted towards the A/Brisbane/59/2007 lineage, the A/H1N1 vaccine strain for the 2008?2009 season. The A/H1N1 2009 (A/H1N1pdm) strains isolated on Corsica Island were characterized by the S220T mutation specific to clade 7 isolates. It should be noted that Corsican isolates formed a separate sub-clade of clade 7 as a consequence of the presence of the fixed substitution D222E.
The percentages of the perfect match vaccine efficacy, estimated by using the p<SUB>epitope</SUB> model, against influenza viruses circulating on Corsica Island varied substantially across the four seasons analyzed, and tend to be highest for A/H1N1 compared with A/H3N2 vaccines, suggesting that cross-immunity seems to be stronger for the H1 HA gene.
Conclusion
The molecular analysis of the HA gene of influenza viruses that circulated on Corsica Island between 2006?2010 showed for each season the presence of a dominant lineage characterized by at least one fixed mutation. The A/H3N2 and A/H1N1pdm isolates were characterized by multiples fixation at antigenic sites. The fixation of specific mutations at each outbreak could be explained by the combination of a neutral phenomenon and a founder effect, favoring the presence of a dominant lineage in a closed environment such as Corsica Island.
Citation: Falchi A, Amoros JP, Arena C, Arrighi J, Casabianca F, et al. (2011) Genetic Structure of Human A/H1N1 and A/H3N2 Influenza Virus on Corsica Island: Phylogenetic Analysis and Vaccine Strain Match, 2006?2010. PLoS ONE 6(9): e24471. doi:10.1371/journal.pone.0024471
Editor: Malcolm Gracie Semple, University of Liverpool, United Kingdom
Received: April 27, 2011; Accepted: August 11, 2011; Published: September 14, 2011
Copyright: ? 2011 Falchi et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: Corsican Economic Development Agency and the FEDER programme provided funding and support for the design and conduct of the study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: falchi@u707.jussieu.fr
- -------Alessandra Falchi<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP><SUP>,</SUP><SUP>3</SUP><SUP>,</SUP><SUP>4</SUP><SUP>*</SUP>, Jean Pierre Amoros<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP><SUP>,</SUP><SUP>3</SUP>, Christophe Arena<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP><SUP>,</SUP><SUP>3</SUP><SUP>,</SUP><SUP>4</SUP>, Jean Arrighi<SUP>4</SUP>, Fran?ois Casabianca<SUP>5</SUP>, Laurent Andreoletti<SUP>6</SUP><SUP>,</SUP><SUP>7</SUP>, Cl?ment Turbelin<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Antoine Flahault<SUP>8</SUP>, Thierry Blanchon<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Thomas Hanslik<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Laurent Varesi<SUP>3</SUP>
1 INSERM, UMR-S 707, F-75012, Paris, France, 2 University Pierre and Marie Curie, Universit? Paris 06, UMR-S U707, F-75012, Paris, France, 3 Laboratory of Virology, University of Corsica, Corsica, France, 4 Observatoire R?gionale de la Sant?, Ajaccio, France, 5 Institut national de la Recherche Agronomique, Corte, France, 6 Unit? de Virologie M?dicale et Mol?culaire, Centre Hospitalier Universitaire, Reims, France, 7 IFR 53/EA-4303 (DAT/PPCIDH), Facult? de M?decine, Reims, France, 8 EHESP School of Public Health, Rennes, France
Abstract
Background
The aim of this study was to analyse the genetic patterns of Hemagglutinin (HA) genes of influenza A strains circulating on Corsica Island during the 2006?2009 epidemic seasons and the 2009?2010 pandemic season.
Methods
Nasopharyngeal samples from 371 patients with influenza-like illness (ILI) were collected by General Practitioners (GPs) of the Sentinelles Network through a randomised selection routine.
Results
Phylogenetic analysis of HA revealed that A/H3N2 strains circulating on Corsica were closely related to the WHO recommended vaccine strains in each analyzed season (2006?2007 to 2008?2009). Seasonal Corsican influenza A/H1N1 isolated during the 2007?2008 season had drifted towards the A/Brisbane/59/2007 lineage, the A/H1N1 vaccine strain for the 2008?2009 season. The A/H1N1 2009 (A/H1N1pdm) strains isolated on Corsica Island were characterized by the S220T mutation specific to clade 7 isolates. It should be noted that Corsican isolates formed a separate sub-clade of clade 7 as a consequence of the presence of the fixed substitution D222E.
The percentages of the perfect match vaccine efficacy, estimated by using the p<SUB>epitope</SUB> model, against influenza viruses circulating on Corsica Island varied substantially across the four seasons analyzed, and tend to be highest for A/H1N1 compared with A/H3N2 vaccines, suggesting that cross-immunity seems to be stronger for the H1 HA gene.
Conclusion
The molecular analysis of the HA gene of influenza viruses that circulated on Corsica Island between 2006?2010 showed for each season the presence of a dominant lineage characterized by at least one fixed mutation. The A/H3N2 and A/H1N1pdm isolates were characterized by multiples fixation at antigenic sites. The fixation of specific mutations at each outbreak could be explained by the combination of a neutral phenomenon and a founder effect, favoring the presence of a dominant lineage in a closed environment such as Corsica Island.
Citation: Falchi A, Amoros JP, Arena C, Arrighi J, Casabianca F, et al. (2011) Genetic Structure of Human A/H1N1 and A/H3N2 Influenza Virus on Corsica Island: Phylogenetic Analysis and Vaccine Strain Match, 2006?2010. PLoS ONE 6(9): e24471. doi:10.1371/journal.pone.0024471
Editor: Malcolm Gracie Semple, University of Liverpool, United Kingdom
Received: April 27, 2011; Accepted: August 11, 2011; Published: September 14, 2011
Copyright: ? 2011 Falchi et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: Corsican Economic Development Agency and the FEDER programme provided funding and support for the design and conduct of the study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: falchi@u707.jussieu.fr