Comparative evaluation of the COBAS AmpliPrep/COBAS TaqMan HIV type 1 test (CAP/CTM) and VERSANT HIV type 1 RNA 3.0 assay (bDNA) for quantifying HIV type 1 viral loads in China

In the present study, 277 clinical samples from untreated and treated HIV-1-infected patients with different clades were used to assess the agreement between the COBAS AmpliPrep/COBAS TaqMan HIV-1 test (CAP/CTM) and VERSANT HIV-1 RNA 3.0 Assay (bDNA). A qualitative comparison of the results of the two assays showed concordance for 255 positive and 15 negative samples (94.95%, kappa = 0.798). However, seven samples with viral loads close to the lower limit of detection for CAP/CTM were negative by bDNA. A significant correlation (r = 0.881, p < 0.001) was observed for 253 samples with viral loads within the dynamic ranges of the two assays, and Bland-Altman analysis showed good agreement (96.05%) between the two assays for these 253 samples [mean (+/-2 SD), 0.389(-0.385, 1.163)]. Furthermore, ART drugs had no impact on the performances of the two assays. For samples with different clades predominant in China, the fitted regression line differed significantly from the line of equality, although significant correlations (r = 0.850-0.891, p < 0.001) and good agreements (92.86-97.25%) were found for the two assays. The mean differences for clade B' and BC samples were significant (p < 0.01). Good precision for clade B' samples was achieved for the CAP/CTM (CV: 20.73%) and bDNA (CV: 12.19%) assays. Furthermore, for clades B', BC, and AE, both assays exhibited good linearities (r = 0.9773-0.9998). Thus, the CAP/CTM and bDNA assays could be useful for quantifying HIV-1 RNA in routine clinical samples and monitoring viral loads in treated and untreated HIV-infected patients in China.