High correlation between the Roche COBAS® AmpliPrep/COBAS® TaqMan® HIV-1, v2.0 and the Abbott m2000 RealTime HIV-1 assays for quantification of viral load in HIV-1 B and non-B subtypes.

BACKGROUND

HIV-1 viral load assays are critical tools to monitor antiretroviral therapy efficacy in HIV-infected patients. Two assays based on real-time PCR are available, the Abbott Real-Time HIV-1 assay (Abbott assay) and the new Roche COBAS(®) AmpliPrep/COBAS(®) TaqMan(®) HIV-1 test, v. 2.0 (TaqMan(®) test v2.0).

OBJECTIVES

We have compared the performance of the two assays in 546 clinical plasma specimens of group M strains from Luxembourg and Rwanda.

STUDY

DESIGN

Our analyses focused on subtype inclusivity and platforms accuracy for 328 low level viremia samples.

RESULTS

Strong agreement and linear correlation were observed between the two assays (R(2) = 0.95) over a wide dynamic range. Bland-Altman analysis showed a mean difference of 0.04 log 10 indicating minimal overall viral load quantification differences between both platforms. One subtype C was severely underquantified by TaqMan(®) test v2.0 for which sequence analysis revealed multiple mismatches between the viral sequence and the primer/probe regions. A non significant lower quantification of the Abbott assay was shown for subtype A1 with a mean log 10 difference of 0.24. For specimens under 200 cp/mL, the overall agreement was 90% at the cut-off of 50 cp/mL and 67% at assay's lower limit of detection of 20 and 40 cp/mL. 309 samples were retested by the COBAS(®) AMPLICOR(®) HIV-1 MONITOR Test, v. 1.5 and a lack of agreement between the three assays around their lower limit of quantification was revealed.

CONCLUSIONS

Both real-time tests were closely comparable in the quantification of viral load specimens of ten HIV-1 subtypes and recombinant forms.