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J Acquir Immune Defic Syndr. 2016 Dec 15;73(5):581-588.

Performance of the Bio-Rad Geenius HIV1/2 Supplemental Assay in Detecting "Recent" HIV Infection and Calculating Population Incidence.

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*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.



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.


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.


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.


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.


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.

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