Evaluation of the Roche Cobas AmpliPrep/Cobas TaqMan HIV-1 test and identification of rare polymorphisms potentially affecting assay performance.
We evaluated the FDA-approved Roche Cobas AmpliPrep/Cobas TaqMan (CAP/CTM) HIV-1 viral load assay for sensitivity, reproducibility, linearity, HIV-1 subtype detection, and correlation to the Roche Amplicor HIV-1 monitor test, version 1.5 (Amplicor). The limit of detection calculated by probit analysis was 23.8 copies/ml using the 2nd International WHO Standard and 30.8 copies/ml using Viral Quality Assurance (VQA) standard material. Serial dilutions of six patient samples were used to determine inter- and intra-assay reproducibility and linearity, which were very good (<8% coefficient of variation [CV]; between approximately 1.7 and 7.0 log(10) copies/ml). Subtype detection was evaluated in the CAP/CTM, Amplicor, and Bayer Versant HIV-1 bDNA 3.0 (Versant) assays using a commercially available panel. Versant averaged 0.829 log(10) copies/ml lower than CAP/CTM and Amplicor averaged 0.427 log(10) copies/ml lower than CAP/CTM for the subtype panel. Correlation with samples previously tested by Amplicor was excellent (R(2) = 0.884; average difference [Amplicor value minus CAP/CTM value], 0.008 log(10) copies/ml). Of the 305 HIV samples tested, 7 samples generated CAP/CTM titers between 1.0 and 2.75 log(10) copies/ml lower than those for Amplicor. Three of these samples revealed primer and probe mismatches that could account for the discrepancies. Otherwise, the CAP/CTM assay exhibits excellent sensitivity, dynamic range, reproducibility, and correlation with Amplicor in an automated format.
Pyne
Michael T
MT
ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108, USA. michael.pyne@aruplab.com
Brown
Katherine L
KL
Hillyard
David R
DR
D020137:Base Pair Mismatch; D017931:DNA Primers / Q000235:genetics; D003951:Diagnostic Errors; D005838:Genotype; D015658:HIV Infections / Q000821:virology*; D015497:HIV-1 / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D015345:Oligonucleotide Probes / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics*; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019562:Viral Load / Q000379:methods*
D017931:DNA Primers; D015345:Oligonucleotide Probes; D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic