title: Detection of serotype-specific antibodies to the four dengue viruses using an immune complex binding (ICB) ELISA.
abstract: BACKGROUND
  Dengue virus (DENV) infections are preferentially diagnosed by detection of specific IgM antibodies, DENV NS1 antigen assays or by amplification of viral RNA in serum samples of the patients. The type-specific immunity to the four worldwide circulating DENV serotypes can be determined by neutralization assays. An alternative to the complicated neutralization assays would be helpful to study the serotype-specific immune response in people in DENV hyperendemic areas but also in subjects upon DENV vaccination.
  
  
  METHODS
  In consecutive samples of patients with DENV-1- 4 infection type-specific antibodies were detected using an immune complex binding (ICB) ELISA. During incubation of serum samples and enzyme- labeled recombinant envelope domain III (EDIII) antigens immune complexes (ICs) are formed, which are simultaneously bound to a solid phase coated with an Fc-receptor (CD32). After a single washing procedure the bound labeled ICs can be determined. To further improve type-specific reactions high concentrations of competing heterologous unlabeled ED III proteins were added to the labeled antigens.
  
  
  RESULTS
  Follow-up serum samples of 64 patients with RT-PCR confirmed primary DENV-1, -2, -3 or -4 infections were tested against four enzyme-labeled recombinant DENV EDIII antigens. Antibodies to the EDIII antigens were found in 55 patients (sensitivity 86%). A complete agreement between the serotype detected by PCR in early samples and the serotype-specific antibody in later samples was found. Type-specific anti-EDIII antibodies were first detected 9-20 days after onset of the disease. In 21% of the samples collected from people in Vietnam secondary infections with antibodies to two serotypes could be identified.
  
  
  CONCLUSIONS
  The data obtained with the ICB-ELISA show that after primary DENV infection the corresponding type-specific antibodies are detected in almost all samples collected at least two weeks after onset of the disease. The method will be of value to determine the distribution of the various type-specific anti-DENV antibodies in DENV endemic areas.
authors.affiliation: Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Emmerich
authors.affiliation: Diagnostics Development Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Angela
authors.initials: A
authors.lastname: Mika
authors.affiliation: Department of Virology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Herbert
authors.initials: H
authors.lastname: Schmitz
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D000936:Antigen-Antibody Complex / Q000032:analysis*; D000956:Antigens, Viral / Q000235:genetics; D019411:Clinical Laboratory Techniques / Q000379:methods*; D003715:Dengue / Q000175:diagnosis* / Q000276:immunology; D003716:Dengue Virus / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins / Q000235:genetics; D013997:Time Factors; D014744:Vietnam; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D000936:Antigen-Antibody Complex; D000956:Antigens, Viral; D011994:Recombinant Proteins