Accuracy to 2nd International HIV-1 RNA WHO Standard: Assessment of three generations of quantitative HIV-1 RNA nucleic acid amplification tests

Abstract

Background Standardization of quantitative HIV-1 tests to a global primary standard is required by regulatory authorities to ensure comparability of test results across different assays and platforms of different manufacturers. Objectives and study design Three generations of quantitative HIV-1 tests, the COBAS ® AMPLICOR ® HIV-1 Monitor Test, v1.5 (HIV-1 Monitor test v1.5); the COBAS ® AmpliPrep/COBAS ® TaqMan ® HIV-1 Test (HIV-1 TaqMan ® test v1.0); and the dual-target-based COBAS ® AmpliPrep/COBAS ® TaqMan ® HIV-1 Test, v2.0 (HIV-1 TaqMan ® test v2.0), were assessed for accuracy to World Health Organization (WHO) 2nd International Standard for human immunodeficiency virus 1 (HIV-1) RNA (NIBSC code 97/650) at concentration levels below 1667 IU/mL including relevant medical decision points. Results With the 2nd WHO Standard the mean difference across all concentrations was −0.07 log 10 for the HIV-1 Monitor test v1.5; +0.12 log 10 for the HIV-1 TaqMan ® test v1.0; and +0.09 log 10 for the HIV-1 TaqMan ® test v2.0. Linearity, including concentrations below the claimed limit of quantitation, was demonstrated for HIV-1 TaqMan ® test v2.0. The HIV-1 TaqMan ® test v1.0 showed a trend towards higher quantitation at very low concentration levels and the HIV-1 Monitor test v1.5 had a tendency towards lower quantitation at low concentration levels. Conclusions All three assays are closely traceable to the primary WHO HIV-1 RNA standard for in vitro diagnostic IVD assays. Compared to the other two assays, the HIV-1 TaqMan ® test v2.0 showed better linearity around the limit of detection and below.