Molecular characterization of influenza B viruses circulating in Northern Italy during the 2001-2002 epidemic season

Filippo Ansaldi, Pierlanfranco D'Agaro, Daniela De Florentiis, Simona Puzelli, Yi Pu Lin, Victoria Gregory, Michael Bennett, Isabella Donatelli, Roberto Gasparini, Pietro Crovari, Alan Hay, Cesare Campello

Research output: Contribution to journalArticlepeer-review


During the 2001-2002 influenza season, virological surveillance highlighted the predominant circulation of B viruses (86% of isolates) in Italy, in contrast to many other countries in Europe and North America where AH3N2 viruses were isolated most frequently, and in contrast to the infrequent isolation of B viruses in Italy during the previous two years. Associated with this predominance of influenza B was the re-emergence of B/Victoria/2/87-lineage viruses, closely related to B viruses prevalent during the 1980s, which are distinct antigenically and genetically from circulating B/Sichuan/379/99-like viruses of the B/Yamagata/16/88 lineage, which predominated in most parts of the world during the last 10 years. Ninety-four viruses isolated in two regions of northern Italy were characterized, 50 by direct sequencing of haemagglutinin (HA). Viruses of both Victoria and Yamagata lineages co-circulated throughout the 12 weeks of the influenza season. The HAs of the Yamagata lineage viruses were heterogeneous and comprised two sublineages, represented by B/Sichuan/379/99 and B/Harbin/7/94, whereas the Victoria-lineage viruses were more homogeneous and closely related to B/Hong Kong/330/ 01, the current prototype vaccine strain. The antigenic and genetic characteristics of the viruses correlated with certain epidemiological features. In particular, the low age (

Original languageEnglish
Pages (from-to)463-469
Number of pages7
JournalJournal of Medical Virology
Issue number3
Publication statusPublished - Jul 1 2003


  • Haemagglutinin
  • Influenza B virus
  • Molecular epidemiology
  • Sequence analysis

ASJC Scopus subject areas

  • Virology


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