title: High serum levels of norovirus genotype-specific blocking antibodies correlate with protection from infection in children.
abstract: BACKGROUND
  Norovirus is a common cause of acute gastroenteritis in children. Serum immunoglobulin G (IgG) antibodies have been implicated in protection against norovirus-associated gastroenteritis, but the level, specificity, and functionality necessary for protection remain to be elucidated.
  
  
  METHODS
  Norovirus-specific IgG antibodies to genogroup II (GII)-4-2010 New Orleans (NO), GII-4-1999, GII-12-1998, GI-1-2001, and GI-3-2002 virus-like particles (VLPs) were determined by enzyme-linked immunosorbent assay in serum samples collected from children who presented to the hospital because of acute norovirus gastroenteritis in 2009-2011. The blocking activity of the antibodies was tested in a surrogate neutralization assay.
  
  
  RESULTS
  Most norovirus infections (62.8%) in the study population were caused by a GII-4 NO variant. Children who acquired GII-4 NO infection had a low preexisting type-specific IgG level and blocking activity of the sera, in contrast to children infected with other GII genotypes. Following GII-4 NO infection, genotype-specific seroconversion and a corresponding increase in blocking antibody potential was observed. Although seroconversion to the heterologous GII-4-1999 variant was observed, there was no corresponding increase in the specific blocking antibody titer. There was no concomitant seroconversion against GI VLPs, indicating a highly genogroup-specific antibody response.
  
  
  CONCLUSIONS
  High preexisting norovirus genotype-specific serum IgG titers and blocking activity in children indicate protection from norovirus infection in a strain-specific manner.
authors: Vaccine Research Center, University of Tampere Medical School.
authors: Maria
authors: M
authors: Malm
authors: Vaccine Research Center, University of Tampere Medical School.
authors: Hanni
authors: H
authors: Uusi-Kerttula
authors: Vaccine Research Center, University of Tampere Medical School Department of Pediatrics, Tampere University Hospital, Finland.
authors: Timo
authors: T
authors: Vesikari
authors: Vaccine Research Center, University of Tampere Medical School.
authors: Vesna
authors: V
authors: Blazevic
mesh_terms: D000367:Age Factors; D019138:Antibodies, Blocking / Q000097:blood / Q000276:immunology*; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology*; D017250:Caliciviridae Infections / Q000097:blood / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005759:Gastroenteritis / Q000097:blood / Q000276:immunology*; D005838:Genotype; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007223:Infant; D007231:Infant, Newborn; D029322:Norovirus / Q000235:genetics* / Q000276:immunology*
chemical_list: D019138:Antibodies, Blocking; D000914:Antibodies, Viral; D007074:Immunoglobulin G
keywords: antibodies; blocking; children; norovirus; protection