Multicenter Evaluation of the New Abbott RealTime Assays for Quantitative Detection of Human Immunodeficiency Virus Type 1 and Hepatitis C Virus RNA

Abstract

The analytical performances of the new Abbott RealTime hepatitis C virus (HCV) and human immunodeficiency virus type 1 viral load assays were compared at nine laboratories with different competitor assays. These included the Abbott LcX, Bayer Versant bDNA, Roche COBAS Amplicor, and Roche COBAS TaqMan assays. Two different protocols used during the testing period with and without a pre-m1000 RNA isolation spin were compared. The difference proved to be nonsignificant. A uracil-N-glycosylase (UNG) contamination control option in the HCV test for previous Roche COBAS Amplicor users was evaluated. It proved to decrease amplicon carryover by 100-fold independent of the amplicon input concentration. The protocol including UNG proved to overcome problems with false-positive negative controls. Comparison with other assays revealed only minor differences. The largest difference was observed between the Abbott HCV RealTime assay and the Roche COBAS Amplicor HCV Monitor version 2.0 assay.Hepatitis C virus (HCV) and human immunodeficiency virus type 1 (HIV-1) are major causes of mortality in both developing and developed countries. For both viruses, relatively effective therapies have been available in developed countries for quite some time. HCV and HIV-1 viral loads are important parameters in patient management both before initiating therapy and during therapy. The decline of the HCV viral load during the first 3 months of therapy is, for instance, a strong indicator of the final outcome of therapy (9, 23). Moreover, in many countries, the HCV viral load in infected health care workers determines whether they are allowed to perform surgical procedures. HIV-1 viral load is monitored during therapy, and a viral load above a certain threshold, which may differ per treating physician, requires a switch in medication (6, 13).The first tests that were described for determining the viral load were based on target amplification techniques like reverse transcriptase PCR (RT-PCR) and nucleic acid sequence-based amplification (NASBA). These tests had readout on agarose gel or readout with enzymatic detection of the amplicon after amplification with biotinylated primers (1, 3, 15, 17). Subsequently, signal amplification techniques were developed for the quantitative detection of HCV and HIV-1 (5, 16). Those techniques were improved and commercialized. The suppliers of the most widely used systems at the moment are Roche and Abbott, for RT-PCR-based systems (the COBAS Amplicor and LcX systems, respectively); bioMerieux (formerly Organon Technica), with a NASBA-based technique; and Bayer, with the Versant bDNA system being a signal amplification technique (4,18,19). Each technique has its own advantages and disadvantages. The relatively small dynamic range is a disadvantage that all current assay formats have in common. All assay formats are also rather sensitive to contamination, especially at the lower limit of detection (21). Handling of the sample after target amplification is a major cause of contamination for the NASBA-and RT-PC...

Performance of the Abbott RealTime and Roche Cobas TaqMan Hepatitis C Virus (HCV) Assays for Quantification of HCV Genotypes

“…However, for subtypes 1a and 2b, the mean difference in VL was not significantly different from non-1a or non-2b specimens, respectively, indicating that the underlying reason for the large discrepancy in VL results for these specimens was not related to subtype. The observed precision, linearity, and sensitivity of the ART assay reported here are similar to results from other laboratories and testing environments (2,5,15,(17)(18)(19)22). In addition, the negative bias of results from the CAP-CTM assay compared to those from the ART assay that we described is consistent with most (14-16), although not all (2, 17), published studies.…”

Performance Evaluation of the New Roche Cobas AmpliPrep/Cobas TaqMan HIV-1 Test Version 2.0 for Quantification of Human Immunodeficiency Virus Type 1 RNA

“…We have previously shown that lack of an UNG system in real-time viral load measurement may pose a significant problem for laboratories that used to measure HCV RNA with CA v1.5 and switch to the use of the Abbott real-time HCV assay, which has no UNG contamination control system built in to its reaction (20). In the present paper, we demonstrate that the UNG system of CAP/ CTM v1.0 and v2.0 is as efficient as the CAP/CA v1.5 UNG system in elimination of dUTP-positive amplicons derived from CAP/CA v1.5.…”

Performance of Three Commercial Viral Load Assays, Versant Human Immunodeficiency Virus Type 1 (HIV-1) RNA bDNA v3.0, Cobas AmpliPrep/Cobas TaqMan HIV-1, and NucliSens HIV-1 EasyQ v1.2, Testing HIV-1 Non-B Subtypes and Recombinant Variants

“…However, all currently available tests have been designed mainly for HIV-1 subtype B. Several reports have noticed differences obtained when quantifying HIV-1 non-B subtypes with different methodologies (5,7,12,14,25,26,28). Moreover, failure to detect non-B subtypes by viral load techniques has been previously described (10,11).…”