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. 2016 Dec 15;73(5):581-588.
doi: 10.1097/QAI.0000000000001146.

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

Free PMC article

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

Sheila M Keating et al. J Acquir Immune Defic Syndr. .
Free PMC article


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.

Design: 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.

Conflict of interest statement

All of the data analysis for this manuscript was performed by the CEPHIA group. For the remaining authors none were declared.


Antigen-specific band intensities. A, Box-and-whisker plots of band intensities, as a function of time since infection (in 6-month intervals), for p31, gp160, and gp41. B, Pairwise scatter plots of band intensities for p31, gp160, and gp41. Excludes treated subjects and SCOPE elite controllers.
Incidence assay results over time since infection. A, Box-and-whisker plots of the Geenius result, as a function of time since infection. Results are summarized for each 6-month interval after infection, and results for all specimens drawn more than 2 years after infection are captured in the rightmost box plot. B, Proportion of “recent” results (using a cutoff of 1.5) as a function of time since infection (with a 95% CI), stratified by HIV subtype (B, C, A1, and D). Excludes treated subjects and SCOPE elite controllers.
Reproducibility of assay results. Box-and-whisker plots of the 25 repeat measurements for the 3 blinded controls (A–C) and 6–10 repeat measurements for the 4 labeled controls (D–G), for each band used as well as the Geenius index result.
Sensitivity of assay results to variations in testing procedures. For each of the 4 specimens (distinguished by marker shape), the individual measurements are shown by markers, and mean measurements connected by dashed lines. The input plasma volume is varied (left plot) or number of drops of buffer is varied (right plot).

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