title: Characterisation of a household norovirus outbreak occurred in Valencia (Spain).
abstract: BACKGROUND
  Human noroviruses (NoVs) are the main cause of non-bacterial gastroenteritis worldwide. Several studies have linked human susceptibility to NoVs with the expression of histo-blood group antigens (HBGAs). In January 2012, a NoV gastroenteritis outbreak affected a household in Valencia, Spain, and the personal susceptibility to NoV was investigated.
  
  
  METHODS
  To reach this aim 8 members of the affected household were recruited for this study and their secretor status, ABO and Lewis antigens were determined. NoV-specific saliva IgA and serum IgG antibody titers were analyzed. Their capacity to block viral binding to saliva receptors was analyzed, using virus-like particles (VLPs) of the NoV GII.4 genotype, 2006b variant, and saliva from a secretor O blood type donor.
  
  
  RESULTS
  The most relevant finding was that an asymptomatic non-secretor individual shed NoVs in his stools. Interestingly, anti-NoV IgA antibody titers in saliva from secretor and non-secretor individuals showed no differences. On the contrary, high titers of NoV-specific IgG antibody were found in both convalescent sera and in sera collected 1 year post-infection, but only from secretor individuals. NoV GII.4-2006b VLP binding to receptors present in the saliva was efficiently blocked only by sera from secretor positive individuals.
  
  
  CONCLUSIONS
  Despite the small number of individuals involved in this outbreak, this study reinforces the idea that susceptibility to human NoV is both dependent on the HBGA profile of the individuals as well as on the viral genotype and variant. We also show that the immunity to NoV lasts for at least 1 year after infection, demonstrating that symptomatic infections strongly stimulate immune responses.
authors.affiliation: Department of Microbiology, School of Medicine, University of Valencia, Avda. Blasco Ibáñez 17, 46010, Valencia, Spain.
authors.forename: Noelia
authors.initials: N
authors.lastname: Carmona-Vicente
authors.affiliation: Department of Microbiology, School of Medicine, University of Valencia, Avda. Blasco Ibáñez 17, 46010, Valencia, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Fernández-Jiménez
authors.affiliation: Department of Microbiology, School of Medicine, University of Valencia, Avda. Blasco Ibáñez 17, 46010, Valencia, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: Vila-Vicent
authors.affiliation: Department of Microbiology, School of Medicine, University of Valencia, Avda. Blasco Ibáñez 17, 46010, Valencia, Spain. jesus.rodriguez@uv.es.
authors.forename: Jesús
authors.initials: J
authors.lastname: Rodríguez-Díaz
authors.affiliation: Department of Microbiology, School of Medicine, University of Valencia, Avda. Blasco Ibáñez 17, 46010, Valencia, Spain. javier.buesa@uv.es.
authors.forename: Javier
authors.initials: J
authors.lastname: Buesa
mesh_terms: D000328:Adult; D017250:Caliciviridae Infections / Q000453:epidemiology*; D002648:Child; D004196:Disease Outbreaks; D005191:Family Characteristics; D005243:Feces / Q000821:virology; D005260:Female; D005759:Gastroenteritis / Q000453:epidemiology*; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D029322:Norovirus / Q000235:genetics / Q000302:isolation & purification*; D012463:Saliva / Q000821:virology; D013030:Spain / Q000453:epidemiology
keywords: Binding assay; FUT2; Histo-blood group antigens; IgA; IgG; Norovirus; Secretor; Susceptibility; Virus-like particles