Improved HIV-1 RNA quantitation by COBAS® AmpliPrep/COBAS® TaqMan® HIV-1 Test, v2.0 using a novel dual-target approach

BackgroundHIV-1 RNA viral load is a key parameter for reliable treatment monitoring of HIV-1 infection. Accurate HIV-1 RNA quantitation can be impaired by primer and probe sequence polymorphisms as a result of tremendous genetic diversity and ongoing evolution of HIV-1. A novel dual HIV-1 target amplification approach was realized in the quantitative COBAS® AmpliPrep/COBAS® TaqMan® HIV-1 Test, v2.0 (HIV-1 TaqMan® test v2.0) to cope with the high genetic diversity of the virus.Objectives and study designThe performance of the new assay was evaluated for sensitivity, dynamic range, precision, subtype inclusivity, diagnostic and analytical specificity, interfering substances, and correlation with the COBAS® AmpliPrep/COBAS® TaqMan® HIV-1 (HIV-1 TaqMan® test v1.0) predecessor test in patients specimens.ResultsThe new assay demonstrated a sensitivity of 20 copies/mL, a linear measuring range of 20–10,000,000 copies/mL, with a lower limit of quantitation of 20 copies/mL. HIV-1 Group M subtypes and HIV-1 Group O were quantified within ±0.3 log10 of the assigned titers. Specificity was 100% in 660 tested specimens, no cross reactivity was found for 15 pathogens nor any interference for endogenous substances or 29 drugs. Good comparability with the predecessor assay was demonstrated in 82 positive patient samples. In selected clinical samples 35/66 specimens were found underquantitated in the predecessor assay; all were quantitated correctly in the new assay.ConclusionsThe dual-target approach for the HIV-1 TaqMan® test v2.0 enables superior HIV-1 Group M subtype coverage including HIV-1 Group O detection. Correct quantitation of specimens underquantitated in the HIV-1 TaqMan® test v1.0 test was demonstrated.