title: Detailed analysis of the genetic evolution of influenza virus during the course of an epidemic.
abstract: The genetic variability of influenza virus is usually studied with sequences selected over numerous years and countries, and rarely within a single season. Here we examined the viral evolution and the correlation between genetic and clinical features during an epidemic. From a French prospective household-based study in 1999-2000, 99 infected patients were randomly selected. The HA1 genomic domain was sequenced. Phylogenetic analysis showed the existence of two groups of A/H3N2 viruses. We found no distinct pattern of genomic evolution within either group according to time. A spatial correlation with the nucleotide distances was shown. The average nucleotide diversity was 3.4x10-3 nucleotides per site, and did not differ between the groups. A lower number of segregating sites was observed in patients who experienced influenza-like symptoms during the previous epidemic. These results suggest that the influenza virus undergoes regular HA1 nucleotide changes, but without clonal expansion of mutant strains within a single epidemic.
authors.affiliation: INSERM U707, Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Lavenu
authors.forename: M
authors.initials: M
authors.lastname: Leruez-Ville
authors.forename: M-L
authors.initials: ML
authors.lastname: Chaix
authors.forename: P-Y
authors.initials: PY
authors.lastname: Boelle
authors.forename: S
authors.initials: S
authors.lastname: Rogez
authors.forename: F
authors.initials: F
authors.lastname: Freymuth
authors.forename: A
authors.initials: A
authors.lastname: Hay
authors.forename: C
authors.initials: C
authors.lastname: Rouzioux
authors.forename: F
authors.initials: F
authors.lastname: Carrat
mesh_terms: D000328:Adult; D000368:Aged; D001483:Base Sequence; D019143:Evolution, Molecular; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics*; D007251:Influenza, Human / Q000453:epidemiology*; D008875:Middle Aged; D011446:Prospective Studies
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus