Background and aims: HIV-1 RNA viral load (VL) in plasma samples of HIV-1-positive patients is used to assess the level of viral replication, the risk of disease progression, and the response and efficacy to antiretroviral treatment. Knowing the performance of different tests for HIV-1 RNA detection is, therefore, important for clinical care. This study compared the performance of the recently introduced Aptima HIV-1 Quant Dx assay (Hologic, Inc) and the standard COBAS AmpliPrep/COBAS TaqMan HIV-1 v2.0 Test (CAP/CTM2) (Roche Molecular System, Inc) for HIV-1 RNA quantitation.
Methods: Assay performance was assessed using 335 clinical samples, a standard HIV-1 low VL panel, and 2 diluted samples from well-characterized patients infected with different HIV-1 subtypes tested in 5 replicates over 3 days. All samples were tested on both assays to evaluate inter-assay agreement, both qualitatively and quantitively. Altogether, we evaluated assay sensitivity, linearity, accuracy, precision, repeatability, and reproducibility.
Results: Assay agreement for qualitative results in 335 clinical samples was fair (80.6%). Correlation of quantitative assay results (n = 164) was excellent (R 2 = 0.97), with 96.3% of the results within the 95% limit of assay agreement (-0.42 to +0.86 log), and 98.8% within 1 log of each other. Aptima-HIV-1 yielded results, on average, 0.22 log higher than CAP/CTM2. Both assays accurately quantitated the HIV-1 standard at low VL (R 2 ≥ 0.94), with all samples within 0.5 log of the target.
Conclusion: Aptima-HIV-1 assay demonstrated sensitivity, accuracy, reproducibility, and precision for the detection and quantitation of HIV-1 RNA across a wide dynamic range of VLs. Its performance, together with full automation and high throughput, suggests that Aptima-HIV-1 could be a suitable assay for reliable monitoring of HIV-1 VL in patients undergoing treatment.
Keywords: HIV‐1; HIV‐1 RNA quantitation; HIV‐1 subtypes; clinical samples.