Cross-reactive Antibodies in Convalescent SARS Patients' Sera Against the Emerging Novel Human Coronavirus EMC (2012) by Both Immunofluorescent and Neutralizing Antibody Tests

J Infect. 2013 Aug;67(2):130-40. doi: 10.1016/j.jinf.2013.03.015. Epub 2013 Apr 10.

Abstract

Objectives: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Animals
  • Antibodies, Neutralizing / blood
  • Antibodies, Viral / blood*
  • China
  • Coronaviridae / immunology*
  • Cross Reactions*
  • Female
  • Fluorescent Antibody Technique, Indirect / methods
  • Humans
  • Male
  • Middle Aged
  • Neutralization Tests / methods
  • Seroepidemiologic Studies
  • Severe Acute Respiratory Syndrome / immunology*
  • Young Adult

Substances

  • Antibodies, Neutralizing
  • Antibodies, Viral