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Discordances in HIV-1 viral load quantification between Roche Cobas® Amplicor® HIV-1 Monitor v 1.5 and Roche Cobas® Ampliprep/Cobas® Taqman® HIV-1 assays
Presented by Diane Descamps, France.
Damond F.1, Roquebert B.1, Bénard A.2, Collin G.1, Miceli M.1, Yéni P.3, Brun-Vézinet F.1, Descamps D.1
1Hopital Bichat-Claude Bernard, Laboratoire de Virologie, Paris, France, 2INSERM U593, Bordeaux, France, 3Hopital Bichat-Claude Bernard, SMIT, Paris, France
Objectives: To determine the concordance between Roche Cobas Amplicor HIV1 Monitor 1.5 and Roche Cobas Taqman HIV-1 assays for the monitoring of HIV-1 viral load (VL) in clinical practice.
Methods: Since June 2006, HIV-1 infected patients, from Bichat Claude Bernard Hospital (Paris, France), previously monitored for VL testing with the Cobas Amplicor HIV1 Monitor 1.5, have been monitored with the Cobas Taqman HIV-1. EDTA plasma samples from 29 HIV-1 naïve patients showing discrepancies of more than 0.5 log cp/ml between the 2 assays on sequential viral load mesurments, were tested in parallel by both assays. HIV-1 subtypes were determined by pol gene sequencing in 26 out of the 29 patients.
Results: 41 plasma samples were tested by both methods. The mean VL value obtained with the Roche Cobas Taqman System was 1.05 log lower than those obtained with the Roche Cobas Amplicor HIV1 Monitor 1.5 system: 2.92 vs 3.97 log10 cp/ml respectively (p<0.01). The HIV-1 VL log10 values between the 2 assays showed discrepancies ranging from 0.57 to 2.76 log. Patients were infected by HIV-1 subtypes A (n=3), B (n=6), CRF02 (n=14), cpx 11 (n=1), cpx13 (n=1) and G (n=1).
Conclusions: Although the primers for Cobas Monitor 1.5 and Cobas Taqman are located in the same gag region, significant quantification differences were pointed out between the 2 assays, whatever the subtype. These results underline the importance of the design of the primers and probes for viral load assays and should lead the manufacturer to harmonize their assay in order to improve the monitoring of disease progression as well as antiretroviral drugs therapy in HIV-1 infected patients.
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