title: Examination of seroprevalence of coronavirus HKU1 infection with S protein-based ELISA and neutralization assay against viral spike pseudotyped virus.
abstract: BACKGROUND
  Human coronavirus HKU1 (HCoV-HKU1) is a recently identified coronavirus with a global distribution and known to cause mainly respiratory infections.
  
  
  OBJECTIVE
  To investigate the seroepidemiology of HKU1 infections in our local population.
  
  
  METHODS
  An ELISA-based IgG antibody detection assay using recombinant HCoV-HKU1 nucleocapsid and spike (S) proteins (genotype A) were developed for the diagnosis of CoV-HKU1 infections, Additionally, a neutralization antibody assay using the HCoV-HKU1 pseudotyped virus was developed to detect the presence of neutralizing antibodies in serum with antibody positivity in an S protein-based ELISA.
  
  
  RESULTS
  Results of the recombinant S protein-based ELISA were validated with Western blot, immunofluorescence analysis and flow cytometry. The coupled results demonstrated good correlation with Spearmen's coefficient of 0.94. Seroepidemiological study in a local hospital-based setting using this newly developed ELISA showed steadily increasing HCoV-HKU1 seroprevalence in childhood and early adulthood, from 0% in the age group of <10 years old to a plateau of 21.6% in the age group of 31-40 years old.
  
  
  CONCLUSIONS
  Our study demonstrated the usefulness of the S-based ELISA which could be applied to future epidemiological studies of HCoV-HKU1 in other localities.
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, The University of Hong Kong, Hong Kong, PR China.
authors.forename: C M
authors.initials: CM
authors.lastname: Chan
authors.forename: Herman
authors.initials: H
authors.lastname: Tse
authors.forename: S S Y
authors.initials: SS
authors.lastname: Wong
authors.forename: P C Y
authors.initials: PC
authors.lastname: Woo
authors.forename: S K P
authors.initials: SK
authors.lastname: Lau
authors.forename: L
authors.initials: L
authors.lastname: Chen
authors.forename: B J
authors.initials: BJ
authors.lastname: Zheng
authors.forename: J D
authors.initials: JD
authors.lastname: Huang
authors.forename: K Y
authors.initials: KY
authors.lastname: Yuen