Staging of recent HIV-1 infection using Geenius rapid confirmatory assay compared to INNO-LIA, New Lav and Blot 2.2 assays

• Detection of p31 bands is critical for the staging of HIV infection.
• The Geenius assay is a rapid immune-chromatographic test used for HIV confirmation.
• The Geenius assay has a high sensitivity to detect Env bands.
• The Geenius assay do not replace WB or Dot Blot assays for detection of p31 and p24 bands

BackgroundBesides confirmation of HIV seropositivity, Western Blot (WB) assays play an important role for identification of recent infection based on incomplete antibody reactivity and lack of p31 band.ObjectivesWe evaluated the capacities of the Geenius™ HIV1/2 Confirmatory Assay (Bio-Rad), a new generation rapid confirmatory assay based on immune-chromatography and automated reading, for staging of HIV-1 infection.Study designSixteen samples collected during early HIV-1 infections (Fiebig stage III–VI) were tested using the Geenius assay, and compared to HIV Blot 2.2 WB assay (MP Diagnostics), New Lav Blot I WB assay (Bio-Rad) and INNO-LIA™ HIV I/II Score Dot Blot assay (Fujirebio). Results obtained with Geenius and INNO LIA in 47 newly diagnosed chronic HIV-1 infections were also compared.ResultsThe p24 band was less frequently detected in early HIV-1 infections using the Geenius (3/16) compared to the New Lav (15/16, p < 0.0001), INNO-LIA (13/16, p = 0.0011), and Blot 2.2 (13/16, p = 0.0011). Testing samples collected during chronic infection allowed to confirm that p31 band and complete Gag, Pol, Env profiles were less frequently observed using the Geenius assay compared to the INNO LIA assay (p = 0.027 for p31, and p = 0.0015 for complete profile).ConclusionsThe Geenius assay is a simple and rapid test showing a high sensitivity to detect Env bands and to confirm HIV-1 seropositivity during the early phases of infection. However, this test is less suitable for distinguishing between later stages of acute and chronic infections because of a reduced sensitivity to detect the p31 and p24 bands compared to INNO LIA and New Lav assays.