title: Performance of the Bio-Rad Geenius HIV1/2 Supplemental Assay in Detecting "Recent" HIV Infection and Calculating Population Incidence.
abstract: OBJECTIVE
  HIV seroconversion biomarkers are being used in cross-sectional studies for HIV incidence estimation. Bio-Rad Geenius HIV-1/2 Supplemental Assay is an immunochromatographic single-use assay that measures antibodies (Ab) against multiple HIV-1/2 antigens. The objective of this study was to determine whether the Geenius assay could additionally be used for recency estimation.
  
  
  METHODS
  This assay was developed for HIV-1/2 confirmation; however, quantitative data acquired give information on increasing concentration and diversity of antibody responses over time during seroconversion. A quantitative threshold of recent HIV infection was proposed to determine "recent" or "nonrecent" HIV infection; performance using this cutoff was evaluated.
  
  
  METHODS
  We tested 2500 highly characterized specimens from research subjects in the United States, Brazil, and Africa with well-defined durations of HIV infection. Regression and frequency estimation were used to estimate assay properties relevant to HIV incidence measurement: mean duration of recent infection (MDRI), false-recent rate, and assay reproducibility and robustness.
  
  
  RESULTS
  Using the manufacturer's proposed cutoff index of 1.5 to identify "recent" infection, the assay has an estimated false-recent rate of 4.1% (95% CI: 2.2 to 7.0) and MDRI of 179 days (155 to 201) in specimens from treatment-naive subjects, presenting performance challenges similar to other incidence assays. Lower index cutoffs associated with lower MDRI gave a lower rate of false-recent results.
  
  
  CONCLUSIONS
  These data suggest that with additional interpretive analysis of the band intensities using an algorithm and cutoff, the Geenius HIV-1/2 Supplemental Assay can be used to identify recent HIV infection in addition to confirming the presence of HIV-1 and HIV-2 antibodies.
authors: *Blood Systems Research Institute, San Francisco, CA; †University of California, San Francisco, San Francisco, CA; ‡The South African DST/NRF Centre of Excellence Epidemiological Modelling and Analysis (SACEMA), Stellenbosch University, Stellenbosch, South Africa; §Department of Statistical Sciences, University of Cape Town, Cape Town, South Africa; ‖Public Health England, London, United Kingdom; ¶University of California, San Diego, San Diego, CA; #Department of Medical Affairs, International AIDS Vaccine Initiative (IAVI), New York, NY; and **Division of Clinical Immunology and Allergy, School of Medicine, University of São Paulo, São Paulo, Brazil.
authors: Sheila M
authors: SM
authors: Keating
authors: Reshma
authors: R
authors: Kassanjee
authors: Mila
authors: M
authors: Lebedeva
authors: Shelley N
authors: SN
authors: Facente
authors: Jeffrey C
authors: JC
authors: MacArthur
authors: Eduard
authors: E
authors: Grebe
authors: Gary
authors: G
authors: Murphy
authors: Alex
authors: A
authors: Welte
authors: Jeffrey N
authors: JN
authors: Martin
authors: Susan
authors: S
authors: Little
authors: Matthew A
authors: MA
authors: Price
authors: Esper G
authors: EG
authors: Kallas
authors: Michael P
authors: MP
authors: Busch
authors: Christopher D
authors: CD
authors: Pilcher
mesh_terms: D000349:Africa; D000465:Algorithms; D001938:Brazil; D002846:Chromatography, Affinity / Q000379:methods*; D003955:Diagnostic Tests, Routine / Q000379:methods*; D015483:HIV Antibodies / Q000097:blood*; D015658:HIV Infections / Q000175:diagnosis* / Q000453:epidemiology* / Q000821:virology; D015497:HIV-1 / Q000276:immunology*; D015498:HIV-2 / Q000276:immunology*; D015994:Incidence; D008962:Models, Theoretical; D012189:Retrospective Studies; D014481:United States
chemical_list: D015483:HIV Antibodies