title: Cross-reactive antibodies in convalescent SARS patients' sera against the emerging novel human coronavirus EMC (2012) by both immunofluorescent and neutralizing antibody tests.
abstract: OBJECTIVE
  A severe acute respiratory syndrome (SARS)-like disease due to a novel betacoronavirus, human coronavirus EMC (HCoV-EMC), has emerged recently. HCoV-EMC is phylogenetically closely related to Tylonycteris-bat-coronavirus-HKU4 and Pipistrellus-bat-coronavirus-HKU5 in Hong Kong. We conducted a seroprevalence study on archived sera from 94 game-food animal handlers at a wild life market, 28 SARS patients, and 152 healthy blood donors in Southern China to assess the zoonotic potential and evidence for intrusion of HCoV-EMC and related viruses into humans.
  
  
  METHODS
  Anti-HCoV-EMC and anti-SARS-CoV antibodies were detected using screening indirect immunofluorescence (IF) and confirmatory neutralizing antibody tests.
  
  
  RESULTS
  Two (2.1%) animal handlers had IF antibody titer of ≥ 1:20 against both HCoV-EMC and SARS-CoV with neutralizing antibody titer of <1:10. No blood donor had antibody against either virus. Surprisingly, 17/28 (60.7%) of SARS patients had significant IF antibody titers with 7/28 (25%) having anti-HCoV-EMC neutralizing antibodies at low titers which significantly correlated with that of HCoV-OC43. Bioinformatics analysis demonstrated a significant B-cell epitope overlapping the heptad repeat-2 region of Spike protein. Virulence of SARS-CoV over other betacoronaviruses may boost cross-reactive neutralizing antibodies against other betacoronaviruses.
  
  
  CONCLUSIONS
  Convalescent SARS sera may contain cross-reactive antibodies against other betacoronaviruses and confound seroprevalence study for HCoV-EMC.
authors.affiliation: Department of Microbiology, Queen Mary Hospital, The University of Hong Kong, Hong Kong Special Administrative Region.
authors.forename: Kwok-Hung
authors.initials: KH
authors.lastname: Chan
authors.forename: Jasper Fuk-Woo
authors.initials: JF
authors.lastname: Chan
authors.forename: Herman
authors.initials: H
authors.lastname: Tse
authors.forename: Honglin
authors.initials: H
authors.lastname: Chen
authors.forename: Candy Choi-Yi
authors.initials: CC
authors.lastname: Lau
authors.forename: Jian-Piao
authors.initials: JP
authors.lastname: Cai
authors.forename: Alan Ka-Lun
authors.initials: AK
authors.lastname: Tsang
authors.forename: Xincai
authors.initials: X
authors.lastname: Xiao
authors.forename: Kelvin Kai-Wang
authors.initials: KK
authors.lastname: To
authors.forename: Susanna Kar-Pui
authors.initials: SK
authors.lastname: Lau
authors.forename: Patrick Chiu-Yat
authors.initials: PC
authors.lastname: Woo
authors.forename: Bo-Jiang
authors.initials: BJ
authors.lastname: Zheng
authors.forename: Ming
authors.initials: M
authors.lastname: Wang
authors.forename: Kwok-Yung
authors.initials: KY
authors.lastname: Yuen
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood*; D002681:China; D003332:Coronaviridae / Q000276:immunology*; D003429:Cross Reactions; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests / Q000379:methods; D016036:Seroepidemiologic Studies; D045169:Severe Acute Respiratory Syndrome / Q000276:immunology*; D055815:Young Adult
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral