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.