title: Antibody response to respiratory syncytial virus infection in children <18 months old.
abstract: The development of a safe and effective respiratory syncytial virus (RSV) vaccine might be facilitated by knowledge of the natural immune response to this virus. The aims of this study were to evaluate the neutralizing antibody response of a cohort of healthy children <18 months old to RSV infection. During the RSV season, 89 healthy children <18 months old were enrolled and followed up weekly for 12 weeks. At each visit, a nasopharyngeal swab was obtained for RSV detection by real-time polymerase chain reaction (PCR). During the study period, 2 blood samples were drawn and they were used to determine RSV geometric mean neutralizing antibody titres (GMT) against RSV. A total of 35 (39.3%) children had RSV detected during the study period. Among RSV-positive patients, children ≥7 months showed a significantly higher increase in antibody response (p<0.001). A significantly higher number of patients with a ≥4 -fold increase in GMT were ≥7 months old (p = 0.02) and presented lower respiratory tract infections (LRTIs) during the study period (p = 0.01). Viral shedding was longer among children aged ≥7 months (p = 0.06), those with viral load ≥10(6) copies/mL (p = 0.03), and those with LRTIs during the study period (p = 0.03), but it was not associated with the immune response (p = 0.41). In conclusion, natural RSV infection seems to evoke a low immune response in younger children. To be effective in this infant population, which is at highest risk of developing severe LRTIs, vaccines must be able to induce in the first months of life a stronger immune response than that produced by the natural infection.
authors.affiliation: a Paediatric 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: b ReiThera Srl (formerly Okairos) , Viale Città d'Europa 679, Rome , Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Scarselli
authors.affiliation: a Paediatric 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: Mara
authors.initials: M
authors.lastname: Lelii
authors.affiliation: a Paediatric 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: b ReiThera Srl (formerly Okairos) , Viale Città d'Europa 679, Rome , Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Vitelli
authors.affiliation: b ReiThera Srl (formerly Okairos) , Viale Città d'Europa 679, Rome , Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Capone
authors.affiliation: c Unit of Medical Statistics, Biometry and Bioinformatics "G.A. Maccacaro"; Università degli Studi di Milano, Fondazione IRCCS Istituto Nazionale Tumori , Milan , Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Fornili
authors.affiliation: c Unit of Medical Statistics, Biometry and Bioinformatics "G.A. Maccacaro"; Università degli Studi di Milano, Fondazione IRCCS Istituto Nazionale Tumori , Milan , Italy.
authors.forename: Elia
authors.initials: E
authors.lastname: Biganzoli
authors.affiliation: c Unit of Medical Statistics, Biometry and Bioinformatics "G.A. Maccacaro"; Università degli Studi di Milano, Fondazione IRCCS Istituto Nazionale Tumori , Milan , Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Orenti
authors.affiliation: b ReiThera Srl (formerly Okairos) , Viale Città d'Europa 679, Rome , Italy.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Nicosia
authors.affiliation: d Keires AG , Bäumleingasse 18, Basel , Switzerland.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Cortese
authors.affiliation: a Paediatric 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: D000367:Age Factors; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D000917:Antibody Formation; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011446:Prospective Studies; D018357:Respiratory Syncytial Virus Infections / Q000276:immunology* / Q000473:pathology / Q000821:virology; D012136:Respiratory Syncytial Viruses / Q000276:immunology*; D017201:Virus Shedding
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral
keywords: RSV; RSV vaccine; neutralizing antibody; pediatric infectious diseases; respiratory tract infection