In 2017 Bio-Rad Laboratories completed launching the FDA-approved Geenius HIV-1/HIV-2 Supplemental assay to replace Multispot HIV-1/HIV-2 in the current CDC HIV Diagnostic Algorithm. The Geenius cassette contains antibody-binding protein A, which is conjugated to colloidal gold dye particles; HIV-1 (p31, gp160, p24, gp41) and HIV-2 (gp36, gp140) antigens are bound to the membrane solid phase. Serum, plasma, or whole blood may be tested. Geenius uses an automated cassette reader and proprietary software to interpret HIV-1 and HIV-2 results. We report more recent performance data for this system, as well as an investigational protocol for testing dried blood spot (DBS) specimens.
(1) WHO evaluated the Geenius HIV-1/HIV-2 Supplemental testing system with a panel of 1117 specimens. (2) DBS specimens were tested on Geenius using an investigational procedure (40 μL of DBS eluate and one drop of assay buffer). Samples included established infections (131 HIV-1, 31 HIV-2, one dual), 60 seroconversion specimens, and 106 DBS collected by CDC during HIV surveillance.
(1) Geenius sensitivity in the WHO evaluation was 100% and specificity was 97.4%. Seroconversion samples were detected +0.875 days vs. the benchmark. All the mixed titer and reference specimens were correctly classified. (2) Geenius DBS correctly detected HIV-1 and HIV-2 DBS with minor exceptions. DBS seroconversions showed slightly reduced sensitivity vs. plasma.
(1) The Geenius HIV-1/2 Confirmatory Assay was accepted for the WHO list of prequalified diagnostics (March 17, 2017). (2) Results of an investigational Geenius DBS procedure appear promising for settings without capacity for venipuncture.