Comparative evaluation of the automated Roche TaqMan real-time quantitative human immunodeficiency virus type 1 RNA PCR assay and the Roche AMPLICOR version 1.5 conventional PCR assay

The need to evaluate antiviral treatment response and the emergence of resistance have made the human immunodeficiency virus (HIV) viral load assay a major feature of the diagnostic monitoring of HIV-infected individuals. The objective of this study was to evaluate the utility of the recently In Vitro Diagnostic Medical Devices Directive-approved Roche COBAS AmpliPrep/TaqMan96 real-time PCR assay by comparison with the existing Roche COBAS AmpliPrep/AMPLICOR MONITOR conventional PCR assay. EDTA-treated plasma samples from 191 HIV-1-infected individuals were tested for HIV-1 RNA by the AMPLICOR assay and the TaqMan assay. This was a prospective study using 191 pairs of samples from the same bleed per patient. The correlation coefficient of the assays was 98.08%. The mean difference between the assays was 0.05 log(10) copy/ml plasma, with a standard deviation (SD) of 0.27 log(10) copy/ml plasma. Thirteen samples gave results with variances greater than 0.5 log(10) copy/ml plasma, which is our clinical cutoff. Two samples were more than 3 SD different (0.81 log(10) copy/ml plasma). The TaqMan assay appeared to be slightly more sensitive at the lower end of the dynamic range. The assays correlated significantly (P > 0.95) with each other, and the regression analysis was also highly significant (R-2 > 0.95).