Molecular epidemiology of influenza B virus among hospitalized pediatric patients in Northern Italy during the 2015-16 season

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Abstract

BACKGROUND: The influenza B viruses belong to two lineages distinguished by their genetic and antigenic characteristics, which are referred to as the Yamagata and Victoria lineages, designated after their original isolates, B/Yamagata/16/88 and B/Victoria/2/87. The primary aim of this study was to evaluate the molecular characteristics of influenza B viruses circulating in a region of Northern Italy, Lombardia, during the influenza season of 2015-2016. METHODS: Influenza B virus was detected using a respiratory virus panel of assays and an influenza B-specific real-time polymerase chain reaction. The complete influenza B hemagglutinin (HA) gene was amplified and sequenced directly from clinical specimens. Phylogenetic analysis was performed using nucleotide sequences. RESULTS: A total of 71 hospitalized pediatric patients were influenza B positive. Phylogenetic analysis showed that the great majority of influenza B strains (66/71, 93.0%) belonged to the Victoria-lineage and were antigenically like vaccine strain (B/Brisbane/60/2008) included only in the quadrivalent vaccine. In the detected influenza B strains, a series of amino acid changes were observed in the antigenic regions: I117V, V124A, N129D, V146I, N197D, T199A, and A202T. However, only 2 amino acid changes were observed in the HA regions involved in receptor binding or in antibody recognition. CONCLUSIONS: All the influenza B strains identified in this study belonged to the influenza B Victoria lineage not included in the trivalent vaccine commonly used by the general population during the 2015-2016 influenza season in Italy. This indicates that protection against influenza B infection in the vaccinated population was in general very poor during the 2015-2016 influenza season.
Original languageEnglish
Pages (from-to)e0185893
JournalPLoS One
Volume12
Issue number10
DOIs
Publication statusPublished - Oct 19 2017

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Keywords

  • Amino Acid Sequence
  • Child
  • Disease Outbreaks
  • Humans
  • Influenza B virus/classification/genetics
  • Influenza, Human/epidemiology/virology
  • Italy/epidemiology
  • Phylogeny
  • Sequence Homology, Amino Acid
  • Viral Proteins/chemistry

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