title: Molecular characterization of influenza B viruses circulating in northern Italy during the 2001-2002 epidemic season.
abstract: 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 (<14 years) of individuals infected with B/Hong Kong/330/01-like viruses is likely to reflect the greater susceptibility of the youngest cohort, due to lack of previous exposure to Victoria-lineage viruses, and is consistent with the conclusion that vaccination with a B/Sichuan/379/99-like virus would give poor protection against infection with B/Hong Kong/330/01-like (Victoria-lineage) viruses.
authors.affiliation: Department of Public Medicine Sciences, U.C.O. Hygiene and Preventive Medicine, University of Trieste and IRCCS Burlo Garofolo, Trieste, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Ansaldi
authors.forename: Pierlanfranco
authors.initials: P
authors.lastname: D'Agaro
authors.forename: Daniela
authors.initials: D
authors.lastname: De Florentiis
authors.forename: Simona
authors.initials: S
authors.lastname: Puzelli
authors.forename: Yi Pu
authors.initials: YP
authors.lastname: Lin
authors.forename: Victoria
authors.initials: V
authors.lastname: Gregory
authors.forename: Michael
authors.initials: M
authors.lastname: Bennett
authors.forename: Isabella
authors.initials: I
authors.lastname: Donatelli
authors.forename: Roberto
authors.initials: R
authors.lastname: Gasparini
authors.forename: Pietro
authors.initials: P
authors.lastname: Crovari
authors.forename: Alan
authors.initials: A
authors.lastname: Hay
authors.forename: Cesare
authors.initials: C
authors.lastname: Campello
mesh_terms: D000595:Amino Acid Sequence; D004196:Disease Outbreaks; D006389:Hemagglutinins, Viral / Q000235:genetics; D006801:Humans; D009981:Influenza B virus / Q000235:genetics* / Q000276:immunology; D007251:Influenza, Human / Q000453:epidemiology*; D007558:Italy / Q000453:epidemiology; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D018571:Sentinel Surveillance; D017386:Sequence Homology, Amino Acid
chemical_list: D006389:Hemagglutinins, Viral; D012367:RNA, Viral