Comparative performance of the Geenius™ HIV-1/HIV-2 supplemental test in Florida's public health testing population

Abstract

BackgroundThe Centers for Disease Control and Prevention (CDC) published updated guidelines in 2014 for the laboratory diagnosis of HIV in the United States, which recommend use of a supplemental immunoassay (IA) that differentiates HIV-1 from HIV-2 after a repeatedly reactive HIV-1/2 antigen/antibody “Combo” screening test. In October 2014, Bio-Rad Laboratories introduced the FDA-cleared Geenius HIV-1/HIV-2 Supplemental assay and in July 2016, it replaced the Multispot HIV-1/HIV-2 differentiation rapid test as the second test in the HIV diagnostic algorithm. ObjectiveTo compare performance of the new FDA-cleared Bio-Rad Geenius HIV-1/HIV-2 Supplemental assay and the Bio-Rad Multispot HIV-1/HIV-2 differentiation assay for use as the primary supplemental test in the 2014 CDC/APHL HIV Diagnostic Algorithm. Study designTwo sets of specimens were used to assess the performance of Geenius; 340 select retrospective specimens, obtained through routine clinical submissions from individuals seeking HIV serostatus determinations and 10 known HIV-2 antibody reactive specimens provided by Bio-Rad Laboratories. Panels were created and characterized solely by in-house laboratory results. The panels consisted of: algorithm-defined “established HIV-1 infections” (n=250), “acute HIV-1 infections” (n=20), “early HIV-1 infections” (n=10) and “false positive Combo specimens” (n=60). Results•Geenius results for the 250 specimens classified as HIV-1 established infections were HIV-1 Positive (246) or HIV Positive Untypable (4), a 100% concordance with HIV positivity observed with Multispot results (HIV-1 Positive, HIV-2 Negative).•Of the 20 HIV-1 algorithm-defined acute infection specimens (Multispot Negative), 85% (17/20) were Geenius HIV-1 Negative and 15% (3/20) HIV-1 Indeterminate.•Similarly, of the 10 algorithm-defined early infection specimens (MS Indeterminate), 30% (3/10) were Geenius HIV-1 Indeterminate, 60% (6/10) HIV-1 Positive and 10% (1/10) HIV Negative.•Of the 60 false positive HIV-1/2 Combo panel, 98.3% (59/60) were HIV-1 Negative by Geenius and 95% (57/60) were HIV-1 Negative by Multispot.•Geenius was concordant with all HIV-2 antibody positive specimens. ConclusionsThe Geenius assay provides significant advantages over Multispot as an appropriate replacement for the primary supplemental test in the HIV Diagnostic Algorithm. In this retrospective study, Geenius was highly concordant with Multispot, reclassified some acute and early algorithm-defined HIV-1 positive specimens and demonstrated a potential decrease in the number HIV-1 RNA nucleic acid amplification tests needed to complete the diagnostic algorithm.