title: Performance of Bio-Rad and Limiting Antigen Avidity Assays in Detecting Recent HIV Infections Using the Quebec Primary HIV-1 Infection Cohort.
abstract: Accurate and practical biologic tools to estimate HIV incidence is crucial to better monitor the epidemic and evaluate the effectiveness of HIV prevention and treatment programs.
  
  
  
  We evaluated two avidity assays to measure recent HIV infection: the Sedia HIV-1 LAg-Avidity EIA (Sedia Biosciences, Portland) and the Centers for Disease Control and Prevention (CDC)-modified Bio-Rad-Avidity assay (Bio-Rad Laboratories, Mississauga, ON). Longitudinal specimens (n = 473) obtained from 123 treatment-naive seroconverted individuals enrolled in the Primary HIV-1 Infection (PHI) cohort of Quebec were used to determine the average time an individual is considered to be recently infected (mean duration of recent infection; MDRI), for the two avidity assays alone and in combination using a nonparametric survival method analysis. A total of 420 specimens from individuals with established HIV infection (90 individuals from the PHI cohort of Quebec and 330 individuals from the Laboratoire de santé publique du Quebec (LSPQ) serobank) were also tested to investigate false recency rate (FRR).
  
  
  
  The CDC-modified Bio-Rad-Avidity gave an estimated MDRI of 234 days (95% CI 220-249) at the avidity index cutoff of 30% while the Sedia-LAg-Avidity assay gave an estimated MDRI of 120 days (95% CI 109-132) at the normalized optical density (ODn) cutoff of 1.5. The FRR among individuals with established HIV infection was 10.2% (7.5%-13.5%) with the CDC-modified Bio-Rad-Avidity assay as compared to 6.0% (3.9%-8.7%) with the Sedia-LAg-Avidity assay. When optimizing a multiassay algorithm (MAA) that includes sequentially the CDC-modified Bio-Rad-Avidity assay then the Sedia-LAg-Avidity assay EIA (avidity index/ODn: 30%/1.7), the MDRI was 136 days (95% CI 123-148) and the FRR, 3.3% (95% CI 1.8-5.6).
  
  
  
  Multiassay algorithms that include the CDC-modified Bio-Rad-Avidity assay and the Sedia-LAg-Avidity assay performed better than each avidity assay alone. Such 2-assay algorithm that starts with the CDC-modified Bio-Rad-Avidity assay followed by the Sedia-LAg-Avidity assay allowed a better classification of HIV-1 infections.
authors.affiliation: Laboratoire de santé publique du Québec/Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.
authors.forename: Bouchra
authors.initials: B
authors.lastname: Serhir
authors.affiliation: Unité de surveillance des maladies chroniques et de leur déterminants/Institut national de santé publique du Québec, Québec, Québec, Canada.
authors.forename: Denis
authors.initials: D
authors.lastname: Hamel
authors.affiliation: Laboratoire de santé publique du Québec/Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.|Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: Florence
authors.initials: F
authors.lastname: Doualla-Bell
authors.affiliation: Chronic Viral Illness Service and Division of Hematology, McGill University Health Centre, Montreal, Quebec, Canada.|Réseau SIDA Maladies infectieuses, Fonds de la recherche du Québec-Santé Montréal, Montréal, Québec, Canada.
authors.forename: Jean Pierre
authors.initials: JP
authors.lastname: Routy
authors.affiliation: Laboratoire de santé publique du Québec/Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.
authors.forename: Sylvie-Nancy
authors.initials: SN
authors.lastname: Beaulac
authors.affiliation: Réseau SIDA Maladies infectieuses, Fonds de la recherche du Québec-Santé Montréal, Montréal, Québec, Canada.
authors.forename: Mario
authors.initials: M
authors.lastname: Legault
authors.affiliation: Laboratoire de santé publique du Québec/Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.
authors.forename: Micheline
authors.initials: M
authors.lastname: Fauvel
authors.affiliation: Laboratoire de santé publique du Québec/Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.|Réseau SIDA Maladies infectieuses, Fonds de la recherche du Québec-Santé Montréal, Montréal, Québec, Canada.|Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Cécile
authors.initials: C
authors.lastname: Tremblay
mesh_terms: D000328:Adult; D000465:Algorithms; D000956:Antigens, Viral / Q000097:blood*; D005260:Female; D015658:HIV Infections / Q000097:blood* / Q000453:epidemiology; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011792:Quebec / Q000453:epidemiology
chemical_list: D000956:Antigens, Viral