Multicenter comparison of Roche COBAS AMPLICOR MONITOR version 1.5, Organon Teknika NucliSens QT with Extractor, and Bayer Quantiplex version 3.0 for quantification of human immunodeficiency virus type 1 RNA in plasma. (1/39)

The performance and characteristics of Roche COBAS AMPLICOR HIV-1 MONITOR version 1.5 (CA MONITOR 1.5) UltraSensitive (usCA MONITOR 1. 5) and Standard (stCA MONITOR 1.5) procedures, Organon Teknika NucliSens HIV-1 RNA QT with Extractor (NucliSens), and Bayer Quantiplex HIV RNA version 3.0 (bDNA 3.0) were compared in a multicenter trial. Samples used in this study included 460 plasma specimens from human immunodeficiency virus (HIV) type 1 (HIV-1)-infected persons, 100 plasma specimens from HIV antibody (anti-HIV)-negative persons, and culture supernatants of HIV-1 subtype A to E isolates diluted in anti-HIV-negative plasma. Overall, bDNA 3.0 showed the least variation in RNA measures upon repeat testing. For the Roche assays, usCA MONITOR 1.5 displayed less variation in RNA measures than stCA MONITOR 1.5. NucliSens, at an input volume of 2 ml, showed the best sensitivity. Deming regression analysis indicated that the results of all three assays were significantly correlated (P < 0.0001). However, the mean difference in values between CA MONITOR 1.5 and bDNA 3.0 (0.274 log(10) RNA copies/ml; 95% confidence interval, 0.192 to 0.356) was significantly different from 0, indicating that CA MONITOR 1.5 values were regularly higher than bDNA 3.0 values. Upon testing of 100 anti-HIV-negative plasma specimens, usCA MONITOR 1.5 and NucliSens displayed 100% specificity, while bDNA 3.0 showed 98% specificity. NucliSens quantified 2 of 10 non-subtype B viral isolates at 1 log(10) lower than both CA MONITOR 1.5 and bDNA 3.0. For NucliSens, testing of specimens with greater than 1,000 RNA copies/ml at input volumes of 0.1, 0.2, and 2.0 ml did not affect the quality of results. Additional factors differing between assays included specimen throughput and volume requirements, limit of detection, ease of execution, instrument work space, and costs of disposal. These characteristics, along with assay performance, should be considered when one is selecting a viral load assay.  (+info)

Comparative performance of three viral load assays on human immunodeficiency virus type 1 (HIV-1) isolates representing group M (subtypes A to G) and group O: LCx HIV RNA quantitative, AMPLICOR HIV-1 MONITOR version 1.5, and Quantiplex HIV-1 RNA version 3.0. (2/39)

The performance of the LCx HIV RNA Quantitative (LCx HIV), AMPLICOR HIV-1 MONITOR version 1.5 (MONITOR v1.5), and Quantiplex HIV-1 RNA version 3.0 (bDNA v3.0) viral load assays was evaluated with 39 viral isolates (3 A, 7 B, 6 C, 4 D, 8 E, 4 F, 1 G, 4 mosaic, and 2 group O). Quantitation across the assay dynamic ranges was assessed using serial fivefold dilutions of the viruses. In addition, sequences of gag-encoded p24 (gag p24), pol-encoded integrase, and env-encoded gp41 were analyzed to assign group and subtype and to assess nucleotide mismatches at primer and probe binding sites. For group M isolates, quantification was highly correlated among all three assays. In contrast, only the LCx HIV assay reliably quantified group O isolates. The bDNA v3.0 assay detected but consistently underquantified group O viruses, whereas the MONITOR v1.5 test failed to detect group O viruses. Analysis of target regions revealed fewer primer or probe mismatches in the LCx HIV assay than in the MONITOR v1.5 test. Consistent with the high level of nucleotide conservation is the ability of the LCx HIV assay to quantify efficiently human immunodeficiency virus type 1 group M and the genetically diverse group O.  (+info)

Intra- and interlaboratory variabilities of results obtained with the Quantiplex human immunodeficiency virus type 1 RNA bDNA assay, version 3.0. (3/39)

Normal assay variation associated with bDNA tests for human immunodeficiency virus type 1 (HIV-1) RNA performed at two laboratories with different levels of test experience was investigated. Two 5-ml aliquots of blood in EDTA tubes were collected from each patient for whom the HIV-1 bDNA test was ordered. Blood was stored for no more than 4 h at room temperature prior to plasma separation. Plasma was stored at -70 degrees C until transported to the Central Pennsylvania Alliance Laboratory (CPAL; York, Pa.) and to the Hershey Medical Center (Hershey, Pa.) on dry ice. Samples were stored at < or =-70 degrees C at both laboratories prior to testing. Pools of negative (donor), low-HIV-1-RNA-positive, and high-HIV-1-RNA-positive plasma samples were also repeatedly tested at CPAL to determine both intra- and interrun variation. From 11 August 1999 until 14 September 2000, 448 patient specimens were analyzed in parallel at CPAL and Hershey. From 206 samples with results of > or =1,000 copies/ml at CPAL, 148 (72%) of the results varied by < or =0.20 log(10) when tested at Hershey and none varied by >0.50 log(10). However, of 242 specimens with results of <1,000 copies/ml at CPAL, 11 (5%) of the results varied by >0.50 log(10) when tested at Hershey. Of 38 aliquots of HIV-1 RNA pool negative samples included in 13 CPAL bDNA runs, 37 (97%) gave results of <50 copies/ml and 1 (3%) gave a result of 114 copies/ml. Low-positive HIV-1 RNA pool intrarun variation ranged from 0.06 to 0.26 log(10) while the maximum interrun variation was 0.52 log(10). High-positive HIV-1 RNA pool intrarun variation ranged from 0.04 to 0.32 log(10), while the maximum interrun variation was 0.55 log(10). In our patient population, a change in bDNA HIV-1 RNA results of < or =0.50 log(10) over time most likely represents normal laboratory test variation. However, a change of >0.50 log(10), especially if the results are >1,000 copies/ml, is likely to be significant.  (+info)

Quantitation of human immunodeficiency virus type 1 (HIV-1) RNA in cell-free cervicovaginal secretions: comparison of reverse transcription-PCR amplification (AMPLICOR HIV-A MONITOR 1.5) with enhanced-sensitivity branched-DNA assay (Quantiplex 3.0). (4/39)

Two commercially available hypersensitive assays for human immunodeficiency virus type 1 (HIV-1) RNA quantitation, AMPLICOR HIV-1 Monitor Test 1.5 and Quantiplex HIV RNA 3.0, were compared to detect and quantify HIV-1 RNA in the cell-free fraction of cervicovaginal secretions collected by vaginal washing. Three panel specimens were used: pooled cervicovaginal secretions spiked with HIV-1 subtype A or HIV-1 subtype B and cervicovaginal lavages from HIV-positive and HIV-negative women. Compared to the AMPLICOR HIV-1 Monitor Test 1.5 assay, the Quantiplex HIV-1 3.0 assay yielded higher estimates of HIV-1 RNA concentrations in several tested samples spiked with HIV-1 RNA subtype A, as well as subtype B, particularly samples containing low amounts of HIV-1 RNA. The sensitivity and specificity of the AMPLICOR HIV-1 Monitor Test 1.5 assay were 93 and 100%, respectively; the sensitivity and specificity of the Quantiplex HIV RNA 3.0 assay were 97 and 50%, respectively. In conclusion, in quantifying HIV-1 RNA in cervicovaginal secretions, the Quantiplex HIV RNA 3.0 may lack specificity, and the AMPLICOR HIV-1 Monitor Test 1.5 assay, although highly specific, may lack sensitivity.  (+info)

Comparative evaluation of the VERSANT HCV RNA 3.0, QUANTIPLEX HCV RNA 2.0, and COBAS AMPLICOR HCV MONITOR version 2.0 Assays for quantification of hepatitis C virus RNA in serum. (5/39)

A comparison of quantitative results expressed in hepatitis C virus (HCV) international units per milliliter, obtained from the VERSANT HCV RNA 3.0 (bDNA-3.0) assay, the QUANTIPLEX HCV RNA 2.0 (bDNA-2.0) assay, and the COBAS AMPLICOR HCV MONITOR version 2.0 (HCM-2.0) test was performed. A total of 168 patient specimens submitted to the Mayo Clinic Molecular Microbiology Laboratory for HCV quantification or HCV genotyping were studied. Of the specimens tested, 97, 88, and 79% yielded quantitative results within the dynamic range of the bDNA-3.0, bDNA-2.0, and HCM-2.0 assays, respectively. Overall, there was substantial agreement between the results generated by all three assays. A total of 15 out of 29 (52%) of the specimens determined to contain viral loads of <31,746 IU/ml by the bDNA-3.0 assay were categorized as containing viral loads within the range of 31,746 to 500,000 IU/ml by the bDNA-2.0 assay. Although substantial agreement was noted between the results generated by the bDNA-2.0 and bDNA-3.0 assays, a bias toward higher viral titer by the bDNA-2.0 assay was noted (P = 0.001). Likewise, although substantial agreement was noted between the results generated by the HCM-2.0 and bDNA-3.0 assays, a bias toward higher viral titer by the bDNA-3.0 assay was noted (P < or = 0.001). The discrepancy between the HCM-2.0 and bDNA-3.0 results was more pronounced when viral loads were >500,000 IU/ml and resulted in statistically significant differences (P < or = 0.001) in determining whether viral loads were above or below 800,000 IU/ml of HCV RNA, the proposed threshold value for tailoring the duration of combination therapy. The expression of quantitative values in HCV international units per milliliter was a strength of both the bDNA-3.0 and HCM-2.0 assays.  (+info)

Postnatal expression and induction by pregnenolone-16alpha-carbonitrile of the organic anion-transporting polypeptide 2 in rat liver. (6/39)

Newborn rats are more sensitive to the toxic effects of cardiac glycosides than are adult rats. This is associated with a decreased ability to remove cardiac glycosides from blood into the liver. Pregnenolone-16alpha-carbonitrile (PCN), a prototypical rodent CYP3A inducer and pregnane-X-receptor (PXR) ligand, stimulates the hepatic clearance of cardiac glycosides in newborn rats, which results in decreased toxicity of the cardiac glycosides. The mechanism responsible for this phenomenon is not clear; however, if elucidated, it would help in understanding and preventing potential drug-drug interactions. The recently cloned rat organic anion-transporting polypeptide 2 (oatp2) (Slc21a5) is a sinusoidal hepatic uptake transporter, with very high affinities for cardiac glycosides, and thus it was hypothesized that rat oatp2 increases during postnatal development and is inducible by PCN. In the present study, livers were removed from Sprague-Dawley rats from postnatal days (pnd) 0 to 45, in 5-day increments; as well as from pnd 10 to 90, in 10-day increments, after PCN (75 mg/kg i.p., for 4 days) or corn oil (vehicle for PCN) treatment. The protein and mRNA levels of rat oatp2 were determined by Western blot analysis and branched DNA signal amplification technique, respectively. Expression of rat oatp2 protein and mRNA increased gradually during postnatal development. PCN treatment increased liver to body weight ratio in both genders, and dramatically accelerated the maturation of hepatic oatp2 protein and mRNA levels. In summary, rat oatp2 undergoes age-dependent and chemical regulation during postnatal development, and is a potential target for drug-drug and age-drug interactions.  (+info)

Evaluation of the VERSANT HCV RNA 3.0 assay for quantification of hepatitis C virus RNA in serum. (7/39)

We assessed the performance of a new assay (VERSANT HCV RNA 3.0 [bDNA 3.0] assay [Bayer Diagnostics]) to quantitate HCV RNA levels and compared the results of the bDNA 3.0 assay to results of the Quantiplex HCV RNA 2.0 (bDNA 2.0) assay. Samples used in this study included 211 serum specimens from hepatitis C virus (HCV)-infected persons from two sites (Bordeaux and Marseille, France) with different genotypes; 383 serum specimens from HCV antibody-negative, HCV RNA-negative persons; and serial dilutions of World Health Organization (WHO) HCV RNA standard at a titer of 100,000 IU/ml. The specificity of the bDNA 3.0 assay was 98.2%. A high correlation was observed between expected and observed values in all dilutions of WHO standard (r = 0.9982), in serial dilutions of pooled samples (r = 0.9996), and in diluted sera from different HCV genotypes (r = 0.9930 to 0.9995). The standard deviations (SD) for the within-run and between-run reproducibility of the bDNA 3.0 assay were +info)

External quality assessment program for qualitative and quantitative detection of hepatitis C virus RNA in diagnostic virology. (8/39)

To assess the performance of laboratories in detecting and quantifying hepatitis C virus (HCV) RNA levels in HCV-infected patients, we distributed two proficiency panels for qualitative and quantitative HCV RNA testing. The panels were designed by the European Union Quality Control Concerted Action, prepared by Boston Biomedica Inc., and distributed in May 1999 (panel 1) and February 2000 (panel 2). Each panel consisted of two negative samples and six positive samples, with HCV RNA target levels from 200 to 500,000 copies/ml. Panel 1 had four samples with at least 50,000 copies/ml, and panel 2 had two samples with at least 50,000 copies/ml. Fifty-seven laboratories submitted 45 qualitative and 35 quantitative data sets on panel 1, and 81 laboratories submitted 75 qualitative and 48 quantitative data sets on panel 2. In both panels, about two-thirds of the qualitative data sets and >90% of the quantitative data sets were obtained with commercial assays. With each panel, two data sets gave one false-positive result, corresponding to false-positivity rates of 1.3% and 0.8% for panel 1 and panel 2, respectively. Samples containing at least 50,000 copies/ml were found positive in 97% and 99% of the cases with panel 1 and panel 2, respectively. In contrast, the positive samples containing < or =5,000 copies/ml were reported positive in only 71% and 77% of the cases with panel 1 and panel 2, respectively. Adequate or better scores on qualitative results (all results correct or only the low-positive samples missed) were obtained in 84% (panel 1) and 80% (panel 2) of the data sets. In the analysis of quantitative results, 60% (panel 1) and 73% (panel 2) of the data sets obtained an adequate or better score (> or =80% of the positive results within the range of the geometric mean +/- 0.5 log(10)). Our results indicate that considerable improvements in molecular detection and quantitation of HCV have been achieved, particularly through the use of commercial assays. However, the lowest detection levels of many assays are still too high, and further standardization is still needed. Finally, this study underlines the importance of proficiency panels for monitoring the quality of diagnostic laboratories.  (+info)