title: Evaluation of a commercial glycoprotein enzyme-linked immunosorbent assay for measuring vaccine immunity to varicella.
abstract: OBJECTIVE
  To evaluate a recently marketed commercial glycoprotein enzyme-linked immunosorbent assay (gpEIA) kit, the VaccZyme™ VZV gpEIA, for measuring the immunity of varicella-vaccinated children.
  
  
  METHODS
  We investigated the accuracy and reproducibility of the VaccZyme™ VZV gpEIA kit for the detection of antibodies to VZV. We also examined the sensitivity, specificity, and correlation between antibody titers calculated with gpEIA versus fluorescent antibody to membrane antigen (FAMA) by using sera of 349 children, ranging from 1 to 6 years old.
  
  
  RESULTS
  VaccZyme™ VZV gpEIA gave precise and reproducible intra- and inter-assay results. FAMA and gpEIA titers showed a linear correlation (Pearson correlation coefficient=0.987). The sensitivity and specificity of the VaccZyme™ gpEIA was 31.4% and 100%, respectively, when the guidelines of the gpEIA (<100 mIU/mL) and FAMA 1:4 were adopted as cutoff values. However, the maximum sensitivity and specificity were 88.9% and 95.1%, respectively, with the highest correlation (κ=0.840), if the cutoff values were set with gpEIA at 49.7 mIU/mL and FAMA 1:16.
  
  
  CONCLUSIONS
  These results demonstrate that the VaccZyme™ VZV gpEIA kit gave precise and reproducible data for measuring antibody titer after varicella vaccination. The results also showed that the antibody titer calculated with the VaccZyme™ gpEIA kit strongly correlated with the FAMA titer. However, cutoff values should be re-optimized for the evaluation of vaccine immunity.
authors.affiliation: Department of Microbiology, College of Medicine, Yeungnam University, 170 Hyeonchung-ro, Nam-gu, Daegu 705-703, Korea. hspark@ynu.ac.kr.
authors.forename: Yun Hwa
authors.initials: YH
authors.lastname: Kim
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Hwang
authors.forename: Hye Min
authors.initials: HM
authors.lastname: Shim
authors.forename: Eunsil
authors.initials: E
authors.lastname: Lee
authors.forename: Songyong
authors.initials: S
authors.lastname: Park
authors.forename: Hosun
authors.initials: H
authors.lastname: Park
mesh_terms: D000914:Antibodies, Viral / Q000097:blood*; D002644:Chickenpox / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006023:Glycoproteins / Q000276:immunology; D014645:Herpesvirus 3, Human / Q000276:immunology; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D006023:Glycoproteins; D014765:Viral Vaccines
keywords: FAMA test; Varicella; gpEIA; immunogenicity; vaccine