Background: Viral load (VL) quantification is important for the management of HBV, HCV, and HIV-1-infected patients. Several semi- or fully automated systems and assays are available that can be used to measure VL for these and other targets. Research design and methods: We assessed the accuracy, genotype/subtype inclusivity, and precision of four VL assays for three viral targets: cobas 4800 (Roche), cobas 6800 (Roche), Aptima (Hologic) and VERIS (Beckman), using WHO standards, cell culture supernatants and clinical samples. Results: Most results were close to expected values, except for significant under-quantification of HIV-1 group O, HBV genotype C, and D at high VL, and HCV genotype 3 by Aptima, and of HIV-1 CRF01_AE and group N and HCV genotype 3 by VERIS. Precision was comparable between tests except for VERIS HCV, which showed more variability. Aptima and cobas 6800 results agreed well with each other except HBV VL at lower VL (<10,000 IU/mL) where Aptima results tended to be higher. Conclusions: Results from different VL assays may not always agree in certain subsets of patients. Clinicians should we aware of these findings when making treatment decisions.
Keywords: Aptima; HBV; HCV; HIV; VERIS; cobas; viral load.