Evaluation of a Rapid Confirmatory Human Immunodeficiency Virus Test: Overall Performance and Band Analysis

Accurate human immunodeficiency virus diagnosis is required to treat and prevent transmission. HIV western blot (MP-WB) has major drawbacks such as prolonged turnaround times, and high percentages of indeterminate results. To address these issues, the CDC in 2014 recommended the use of an immunological test capable of differentiating anti-HIV-1 antibodies from anti-HIV-2 antibodies for HIV diagnosis. The Geenius™ HIV 1/2 Confirmatory Assay/Bio-Rad is a rapid, single-use immunochromatographic test designed to confirm and differentiate HIV antibodies.

This study, conducted at the Central Virology Laboratory of the Rabat Specialty Hospital, Morocco, evaluated the performance of the Geenius test as an alternative to MP-WB for confirming HIV-1 diagnoses over 24 months. 116 samples were included, 113 patient samples with repeatedly reactive HIV screening test (HIV Combo Ag/Ab) and 3 external quality evaluation programs. Samples were tested by Geenius™ HIV-1/2 confirmatory assay and MP-WB. A nucleic acid amplification test (NAAT) was performed for discordant cases.

Geenius and MP-WB mostly agreed in 95% of the overall, with a Cohen's kappa coefficient at 0.728, indicating substantial agreement. Geenius also produced fewer indeterminate results compared with MP-WB (16.67% vs. 83.33%), mainly in low-reactive samples. At the band level, the highest performances were seen with Gp160 and Gp41, showing concordance rates of 97% and 99%, respectively, with Cohen's kappa coefficient of 0.866 and 0.955. In contrast, the p24 and p31 bands demonstrated lower performances. Among six discordant results, five had low HIV Combo index values and were NAAT confirmed negative. A single high screening ratio and positive NAAT discordant case was classified as acute HIV infection. Excluding indeterminate Geenius results, the Geenius assay displayed 99% sensitivity, 100% specificity, 100% PPV, and 90.9% NPV, which justifies its better diagnostic performance compared to MP-WB.

The Bio-Rad Geenius HIV-1/2 confirmatory test represents a reliable, rapid, and less labor-intensive alternative to MP-WB, offering a simplified approach for confirming HIV diagnoses, with good sensitivity for gp41 and gp160 bands, and can be integrated into diagnostic algorithms.