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Background: HIV-1 viral load assays are essential tools for clinical management of people living with HIV-1., Objectives and Study Design: We evaluated concordance between three assays: the cobas® HIV-1 test for use on the cobas® 6800 and cobas® 8800 systems (cobas HIV-1); the COBAS® TaqMan® HIV-1 Test, v2.0 for use with the High Pure System and the COBAS® AmpliPrep/COBAS® TaqMan® HIV-1 test, v2.0. Analytical sensitivity, precision and accuracy of all three methods were assessed using the WHO 2nd International Standard for HIV-1, with concentrations from 5 to 1000 copies/mL. Accuracy and concordance were evaluated using 212 clinical specimens. Overall percent agreement (OPA) was determined using three different thresholds used as medical decision points., Results: The limit of detection was below 20 copies/mL for each assay. The hit rate for each assay was 100 % for concentrations ≥ 50 copies/mL. Only the cobas HIV-1 test generated quantifiable data for all replicates at 50 copies/mL. Between 50 and 400 copies/mL, results for all assays were accurate within 0.09 log 10 copies/mL, with standard deviation less than 0.14 log 10 copies/mL. The mean difference between paired results in clinical specimens ranged from -0.050 to 0.107 log 10 copies/mL across all assay comparisons. The OPA between pairs of assays ranged from 94.8 to 98.1% at the 50 copies/mL cutoff, and improved to a range of 97.6-99.0% at the 200 copies/mL cutoff. At the 1000 copies/mL cutoff, OPA between assays was 98.5-99.0%., Conclusions: The cobas HIV-1 assay is highly sensitive, accurate and suitable for use in clinical practice., (Copyright © 2021. Published by Elsevier B.V.)

Objective: This study evaluated the performance of the cobas® hepatitis C virus (HCV) Test for use on the cobas® 6800/8800 Systems for the detection and quantification of HCV RNA collected using the cobas® Plasma Separation Card (PSC) compared with plasma samples., Methods: Whole EDTA-venous blood was collected from 50 HCV-positive donors and 140 μL from each donor was spotted onto a PSC and stored either frozen or at ambient temperature. These were compared with matched EDTA-plasma samples. The limit of detection (LoD) of the assay for PSC samples was determined using serial dilutions of the Roche HCV secondary calibration standard. The stability of the PSC samples across a range of timepoints was also assessed., Results: The mean titer difference between ambient and -10 °C storage of PSC samples was 0.04 log10 IU/mL (95% CI: 0.00, 0.07). The mean titer difference between frozen PSC samples and EDTA plasma samples was -1.59 log10 IU/mL (95% CI: -1.66, -1.53) and between ambient PSC samples and EDTA samples was -1.64 log10 IU/mL (95% CI: -1.70, -1.57). Correlation between PSC samples and EDTA plasma was linear in both cases (frozen: slope = 1.039, intercept=-1.839, R 2  = 0.89; ambient: slope = 1.012, intercept=-1.712, R 2  = 0.88). The LoD of the cobas® HCV Test using the PSC was 866 IU/mL (95% CI: 698, 1153 IU/mL) and 408 IU/mL (95% CI: 336, 544 IU/mL) using an optimized Assay Specific Analysis Package., Conclusions: PSC samples correlate well with plasma viral load and demonstrate a LoD below 1000 IU/mL and good stability at ambient temperature for 28 days. A correction factor would allow quantification of HCV viral RNA load from samples collected using a PSC., Competing Interests: Declaration of Competing Interest All authors were employed by Roche Molecular Systems, Inc during the preparation and execution of the study., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

This study evaluated the use of dried blood spot (DBS) for HCV viral load quantification using the COBAS ® AmpliPrep/COBAS ® Taqman ® HCV Quantitative Test v2.0 (CAP/CTM HCV v2), and compared two different procedures for preparation of DBS samples with a Specimen Pre-Extraction (SPEX) reagent (either heated [SPEX with SH] for 10min at 56°C on a thermomixer, or incubated for 1h at room temperature [SPEX at RT]) against the standard plasma input. Whole blood specimens from 48 patients with chronic HCV infection and Whatman ® 903 Protein Saver Cards were used to prepare 35μL DBS. An aliquot of plasma was spun and frozen from each draw. Mean DBS viral load results were compared to the corresponding results from plasma. Correlation between DBS to plasma was linear for both SPEX with SH (R 2 =0.96) and SPEX at RT (R 2 =0.97) procedures, with a constant negative offset of approximately 2.0log 10 IU/mL between whole blood DBS without any adjustments and plasma results. After volume corrections, the mean offset to plasma decreased to -0.39 and -0.36 for the two procedures, respectively. The study demonstrated the use of DBS for HCV viral load correlates well with plasma with a constant offset., (Copyright © 2017 Roche Molecular Systems, Inc. Published by Elsevier B.V. All rights reserved.)