title: Evaluation of an antibody avidity index method for detecting recent human immunodeficiency virus type 1 infection using an automated chemiluminescence immunoassay.
abstract: BACKGROUND
  Recent infection testing algorithms (RITAs) are used in public health surveillance to estimate the incidence of recently acquired HIV-1 infection.
  
  
  OBJECTIVE
  Our aims were (i) to evaluate the precision of the VITROS® Anti-HIV 1+2 automated antibody avidity assay for qualitative detection of antibodies to HIV 1+2 virus; (ii) to validate the accuracy of an automated guanidine-based antibody avidity assay to discriminate between recent and long standing infections using the VITROS 3600 platform; (iii) to compare this method with BED-CEIA assay; and (iv) to evaluate the occurrence of false recent misclassifications by the VITROS antibody avidity assay in patients with a CD4 count <200 cells/μL and in patients on combination antiretroviral therapy (cART).
  
  
  RESULTS
  The VITROS® antibody avidity assay is highly reproducible. The ROC curve analysis of the accuracy of this assay, optimized for sensitivity and specificity, had an AI cut off of ≤0.51, with sensitivity and specificity values of 86.67% (95% CI: 72.51-94.46) and 86.24% (95% CI: 78.00-91.84), respectively. The agreement between VITROS antibody avidity and BED-CEIA assays was good. Misclassifications of long standing infections as recent infection occurred in 8.2% of patients with CD4 <200 cell/μL and 8.7% in patients on combination antiretroviral therapy.
  
  
  CONCLUSIONS
  The VITROS antibody avidity assay is a reliable serological method to detect recent HIV-1 infections and it could be incorporated into a RITA to estimate HIV incidence.
authors: Microbiology Service, Fundació Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain.
authors: Gema
authors: G
authors: Fernández
authors: Infectious Diseases Service, Hospital Clínic/DIBAPS, University of Barcelona, Barcelona, Spain.
authors: Christian
authors: C
authors: Manzardo
authors: Centre for Epidemiological Studies on HIV/STI in Catalonia (CEEISCAT) - ICO, Badalona, Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.
authors: Alexandra
authors: A
authors: Montoliu
authors: Centre for Epidemiological Studies on HIV/STI in Catalonia (CEEISCAT) - ICO, Badalona, Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.
authors: Colin
authors: C
authors: Campbell
authors: Microbiology Service, Fundació Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain.
authors: Gregorio
authors: G
authors: Fernández
authors: Centre for Epidemiological Studies on HIV/STI in Catalonia (CEEISCAT) - ICO, Badalona, Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.
authors: Jordi
authors: J
authors: Casabona
authors: Infectious Diseases Service, Hospital Clínic/DIBAPS, University of Barcelona, Barcelona, Spain.
authors: José Maria
authors: JM
authors: Miró
authors: Microbiology Service, Fundació Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.
authors: Lurdes
authors: L
authors: Matas
authors: Microbiology Service, Fundació Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain.
authors: Belén
authors: B
authors: Rivaya
authors: Centre for Epidemiological Studies on HIV/STI in Catalonia (CEEISCAT) - ICO, Badalona, Barcelona, Spain; Microbiology Service, Fundació Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain. Electronic address: vgsoler@iconcologia.net.
authors: Victoria
authors: V
authors: González
mesh_terms: D015492:AIDS Serodiagnosis / Q000379:methods*; D000915:Antibody Affinity; D015483:HIV Antibodies / Q000097:blood* / Q000276:immunology; D015488:HIV Antigens / Q000276:immunology; D015658:HIV Infections / Q000097:blood*; D015497:HIV-1 / Q000276:immunology*; D015498:HIV-2 / Q000276:immunology; D006801:Humans; D008163:Luminescent Measurements / Q000379:methods*; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D015483:HIV Antibodies; D015488:HIV Antigens
keywords: Avidity index; False recent rate; Human immunodeficiency virus; Incidence; Incidencia; Infección reciente; Recent infection; Tasa de falsos recientes; Virus de la inmunodeficiencia humana; índice de avidez