title: Characteristics and Their Clinical Relevance of Respiratory Syncytial Virus Types and Genotypes Circulating in Northern Italy in Five Consecutive Winter Seasons.
abstract: In order to investigate the genetic diversity and patterns of the co-circulating genotypes of respiratory syncytial virus (RSV) and their possible relationships with the severity of RSV infection, we studied all of the RSV-positive nasopharyngeal samples collected from children during five consecutive winters (2009-2010, 2010-2011, 2011-2012, 2012-2013 and 2013-2014). The RSVs were detected using the respiratory virus panel fast assay and single-tube RT-PCR, their nucleotides were sequenced, and they were tested for positive selection. Of the 165 positive samples, 131 (79.4%) carried RSV-A and 34 (20.6%) RSV-B; both groups co-circulated in all of the study periods, with RSV-A predominating in all the seasons except for winter 2010-2011, which had a predominance of RSV-B. Phylogenetic analysis of the RSV-A sequences identified genotypes NA1 and ON1, the second replacing the first during the last two years of the study period. The RSV-B belonged to genotypes BA9 and BA10. BA9 was detected in all the years of the study whereas BA only desultorily. Comparison of the subjects infected by RSV-A and RSV-B types did not reveal any significant differences, but the children infected by genotype A/NA1 more frequently had lower respiratory tract infections (p<0.0001) and required hospitalisation (p = 0.007) more often than those infected by genotype A/ON1. These findings show that RSV has complex patterns of circulation characterised by the periodical replacement of the predominant genotypes, and indicate that the circulation and pathogenic role of the different RSV strains should be investigated as each may have a different impact on the host. A knowledge of the correlations between types, genotypes and disease severity may also be important in order to be able to include the more virulent strains in future vaccines.
authors.affiliation: Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Susanna
authors.initials: S
authors.lastname: Esposito
authors.affiliation: Molecular Virology Unit, Microbiology and Virology Department Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Piralla
authors.affiliation: Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Zampiero
authors.affiliation: Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Bianchini
authors.affiliation: Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Giada
authors.initials: G
authors.lastname: Di Pietro
authors.affiliation: Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Scala
authors.affiliation: Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Pinzani
authors.affiliation: Emergency Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Emilio
authors.initials: E
authors.lastname: Fossali
authors.affiliation: Molecular Virology Unit, Microbiology and Virology Department Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; Section of Microbiology, Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, Pavia, Italy.
authors.forename: Fausto
authors.initials: F
authors.lastname: Baldanti
authors.affiliation: Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Principi
mesh_terms: D002675:Child, Preschool; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005260:Female; D005838:Genotype; D054884:Host-Pathogen Interactions; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007558:Italy / Q000453:epidemiology; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D015995:Prevalence; D012367:RNA, Viral / Q000235:genetics; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology* / Q000821:virology*; D018113:Respiratory Syncytial Virus, Human / Q000145:classification / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012621:Seasons; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D018076:DNA, Complementary; D012367:RNA, Viral