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Cytomegalovirus (CMV) viral load quantitation is important in diagnosis, follow-up, and monitoring of antiviral therapy in transplanted patients. In this study, it was aimed to compare the results of the two commercial World Health Organization (WHO) International CMV standard calibrated polymerase chain reaction tests, CMV Cobas Ampliprep/Cobas Taqman (CMV-CAP/CTM) (Roche, Germany) and Artus CMV QIASymphony-Rotorgene (CMV-QS-RGQ) (Qiagen, Germany). Both tests were performed simultaneously on 244 plasma samples. The results were measured in copies/ml and converted to IU/ml by multiplying with 0.91 for CMV-CAP/CTM and 1.64 for CMV-QS-RGQ, as specified by the manufacturers. CMV DNA was detected in 174 (71.3%) and was not detected in 52 (21.3%) of the samples and eighteen (7.4%) samples had discordant results by both of the tests. In 16 out of 18 samples with discordance, the viral load was below the dynamic measuring ranges of both tests. In one sample, CMV DNA could not be detected by CMV-CAP/CTM but detected by CMV-QS-RGQ with 497 copies/ml, and 334 copies/ml CMV DNA was detected by CMV-CAP/CTM in another sample where it could not be detected by CMV-QS-RGQ. A high degree of agreement was found between the qualitative results of the both tests (kappa= 0.80, p 0.5 log10 increased and the difference was found as statistically significant (p< 0.001). Calibrating the Roche CMV CAP/CTM and Artus CMV-QS-RGQ tests with the WHO international CMV standard did not increase comparability between quantitative results in plasma samples, on the contrary, it was found that when the results were converted to IU/ml, a measurement difference indicating biologically significant viral replication was detected between the two test results.

Purpose. The analytical performance of the cobas 6800 HIV-1, HBV and HCV assays was verified and evaluated to the COBAS Ampliprep/COBAS TaqMan assays. Methodology. The precision, limit of detection (LoD), limit of quantification (LoQ) and linearity were verified using pooled residual clinical samples. The analytical specificity was verified with negative plasma. HIV-1 analytical reactivity was verified with WHO reference preparations. Accuracy was verified using EQA plasma panels. Evaluation of the equipment was performed using prospectively collected clinical whole blood samples. Results. Excellent precision was demonstrated using both testing protocols (coefficient of variation ≤15 %). The LoDs using the 500 and 200 µl protocols were 20 and 50 cp ml−1 for HIV-1, 10 and 20 IU ml−1 for HBV and 15 and 40 IU ml−1 for HCV, respectively. The LoQs were 40 and 100 cp ml−1 for HIV-1, 20 and 25 IU ml−1 for HBV and 30 and 80 IU ml−1 for HCV, respectively. Assays demonstrated good linearity (R2 ≥0.96). The analytical specificity of the assays was 100 %. There was excellent agreement between the cobas 6800 and CAP/CTM assays (kappa>0.94). The sensitivity, specificity, positive predictive value and negative predictive value for each of the assays were ≥99 %. The cobas HIV-1 and HCV mean quantifications were 0.03 log10 cp ml−1 and 0.17 log10 IU ml−1 higher than the CAP/CTM. The cobas HBV mean quantification was 0.17 log10 IU ml−1 lower than the CAP/CTM. Subtype/genotype specific differences were not observed. Conclusion. Cobas 6800 equipment and assays demonstrated excellent performance and correlated well with CAP/CTM assay results.

BACKGROUND The genetic divergence of HIV-1 group O is high relative to pandemic group M, which could impact detection and quantification of plasma RNA. Recent commercial kits for RNA quantification seem to show good performances in HIV-1/O, but discrepancies are still observed. Here, we compare the performances of 3 commercial assays for the RNA quantification of HIV-1/O. METHODS We studied the RNA quantification of 117 clinical samples using Abbott RealTime HIV-1, Cepheid Xpert HIV-1 Viral Load, or Roche Cobas TaqMan HIV-1 v2. First, we conducted a qualitative description, and second, we focused on a quantitative analysis of the results above 40 cp/mL. The degree of agreement between methods and the strength of the correlation of viral load determination were estimated using Bland-Altman plot and Passing-Bablok regression with the Spearman coefficient, respectively. RESULTS Our 2-by-2 analysis showed that the Abbott and Cepheid assays were very close in terms of correlation and dispersion of points, whereas Roche presented higher values in the highest range of quantification (>5 log10). The Cepheid assay combined better correlation with the consensus value and a lower dispersion of values, leading to an overall better performance of quantification. The quantification was still impacted by intragroup genetic diversity with, here, 1 strain (YBF26). CONCLUSIONS Using a new approach to compare the performances of RNA quantification between more than 2 techniques, we demonstrated that Cepheid could be the most suitable assay for HIV-1/O quantification, although the results from all assays remained strain dependent.

This study evaluated the performance of the Xpert MTB/RIF Ultra assay (Xpert Ultra) to detect smear-negative pulmonary tuberculosis (PTB). Xpert Ultra assay was prospectively performed using bronchial washing fluid (BWF) in comparison to COBAS TaqMan MTB (COBAS) assay and mycobacterial culture. Of the 165 enrolled participants, 27 (16.4%) had PTB based on composite reference standard and 16 (9.7%) had culture-confirmed PTB. By the composite reference standard of PTB, the sensitivity of Xpert Ultra (63.0, 95% confidence interval, CI, 42.4-80.6%) was higher than the COBAS assay (25.9%, P = 0.006), BWF-culture (33.3%, P = 0.029) and sputum-culture (37.0%, P = 0.057). Meanwhile, the specificity of Xpert Ultra was 99.3% which was slightly lower than the 100.0% specificity of the COBAS assay (P = 1.000) and cultures (P = 1.000). Against the reference standard of culture-confirmed PTB, Xpert Ultra also had a higher sensitivity (62.5, 95% CI, 35.4-84.8%) than the COBAS assay (31.3%, P = 0.077) and was similar to BWF-culture (56.3%, P = 0.719) and sputum-culture (62.5%, P = 1.000). However, one subject with previously treated old PTB had a false-positive result on the Xpert Ultra assay. This prospective study showed Xpert Ultra assay using BWF had better sensitivity than COBAS assay and mycobacterial cultures but could represent a false positive in patients with inactive old PTB.

International audience; The high genetic variability of hepatitis B virus (HBV) can impair DNA quantification. Here, we investigate a major underquantification of HBV by the cobas TaqMan HBV assay (CTM; Roche). In France, between 2005 and 2017, HBV DNA was detected in 3,102 blood donations by use of the CTM (95% limit of detection [LOD], 4.8 IU/ml). HBV strains were sequenced in the S region (LOD, ∼30 IU/ml). Concordant (n = 120) and discordant (n = 45) samples were identified according to the agreement between the plasma viral load (pVL) determined by the CTM and sequencing; all samples were also quantified using the RealTime HBV assay (RTH; Abbott). The viral signature, cloning, and mutagenesis were used to characterize the polymorphism responsible for CTM misquantification. A CTM-RTH discordance (>1 log IU/ml) was found in 14/45 samples that had low pVLs and were successfully genotyped (pVL genoS). PreC/C clones of concordant (C1, C2) and discordant (D1, D2) strains were used to challenge the CTM. Strains D1 and D2 were highly underquantified (42- and 368-fold). In clones, mutating the region corresponding to the CTM reverse primer from a discordant sequence to a concordant sequence restored the levels of quantification to 24% (D1→C1) and 59% (D2→C1) of theoretical levels, while mutating the sequence of a concordant strain to that of a discordant strain led to 78-fold (C1→D1) and 146-fold (C1→D2) decreases in quantification. Moreover, mutating positions 1961 and 1962 was enough to induce a 5-fold underquantification. We conclude that the CTM underestimates pVLs for HBV strains with mutations in the reverse primer target. Specifically, the polymorphism at nucleotides 1961 and 1962 is naturally present in 4.79 and 4.22% of genotype A and D strains, which are highly frequent in Europe, leading to a 5-fold decrease in quantification. Quantification using the new-generation Roche C4800 assay is not affected by this polymorphism.

BackgroundSeveral studies have been conducted to compare the use DBS as alternative to plasma specimens, but mainly using Whatman 903®cards as filter paper. The aim of this study was to evaluate Whatman FTA®cards (FTA cards) specimens for HIV-1 viral load testing by comparing it to plasma specimens, using 2 real-Time PCR assays.MethodologyA cross-sectional study was conducted between April 2017 and September 2017, in HIV-1 patients admitted at Yalgado Ouédraogo teaching hospital. Paired FTA cards and plasma specimens were collected and analyzed using Abbott RealTime HIV-1 assay (Abbott) and COBAS®AmpliPrep/COBAS®TaqMan v2.0 (Roche), following manufacturers’ protocol.ResultsA total of 107 patients were included. No Statistical differences (p-value > 0.05) were observed between the mean viral loads obtained from FTA cards and plasma specimens with Roche and Abbott assays. Twenty-nine samples with Roche and 15 samples with Abbott assay showed discrepant results. At viral loads of ≤1000 copies/mL, the sensitivity and specificity of FTA cards were 78.6%, and 100% with Roche, and 92.3% and 95.9% with Abbott. Strong correlation was found between FTA cards and plasma specimens with both assays. With Roche, Bland-Altman analysis showed bias of −0.3 and 95% limits of agreement of −2.6 to 1.8 log10, with 97/99 cases (97.9%) within agreement limits. With Abbott, Bland-Altman analysis showed bias of −0.1 and 95% limits of agreement of −2.3 to 2.1 log10, with 96/99 cases (96.9%) within agreement limits.ConclusionOur study demonstrated the feasibility of using FTA cards filter paper for HIV-1 viral load testing. However, further studies are required for FTA cards filter paper validation in HIV-1 treatment monitoring.

Introduction:quantification of hepatitis B virus DNA, a key element in the management of chronic hepatitis B, allows a more direct and reliable measurement of viral replication and monitoring of the virological response to therapy. Polymerase chain reaction (PCR) platforms performing this quantification and adaptable to intermediate laboratories have been developed. Thus, this study was conducted to evaluate the on-site performance of the AMPLIX® hepatitis B virus (HBV) real-time PCR technique in comparison with the COBAS AmpliPrep™ technique. Methods:performance of the AMPLIX® HBV real-time PCR technique was evaluated with repeatability and intermediate precision (reproducibility) determined. The comparison with COBAS Taqman was performed by testing, in parallel, 42 plasma samples. The statistical analysis using Meth Val® software was focused on correlation and concordance determination. Results:AMPLIX® real-time PCR assay showed good reproducibility for the low (CV=6.65%) and high (CV=3.15%) control levels but also good repeatability for both the low (CV=2.12%) and high (CV=1.60%) concentration levels. Accuracy obtained in our study were less than acceptability limit fixed to 5%. Viral load measurements between Amplix and COBAS Taqman correlated strongly with a correlation coefficient of 0.97%. Concordance analysis gave an average of the differences of 0.54 log IU/L between the viral load measurements of the 2 techniques. Conclusion:based on these results, the Amplix real-time PCR platform for the quantification of HBV DNA can be considered as a reliable system for the monitoring of chronic hepatitis B and also a system adapted to intermediate laboratories.

Background The aim of the study is to evaluate the significance of the Architect anti-HCV signal to cutoff (S/CO) ratios for predicting hepatitis C viremia and determine the optimal S/Co ratio value for Architect anti-HCV assay. Methods The results of patients who underwent HCV RNA quantitative assays because of positive anti-HCV from January 2015 to August 2019 were retrospectively analyzed, including S/Co ratio values, HCV RNA quantitative results, alanine aminotransferase (ALT), and aspartate transaminase (AST) values. Binary logistic regression and Spearman's correlation coefficient were used to analyze the collected data. Receiver-operating characteristics curve (ROC) was applied to analyze the predicting values of the indexes. Results In total, 811 patients were included in our study and HCV viremia was detected in 342 (42.1%) patients. There is no correlation between anti-HCV S/CO ratio and HCV RNA level. The samples with an S/Co ratio between 1 and 4 (271/271, 100%) were all HCV RNA negative. The area under the ROC curve of anti-HCV S/CO ratio was 0.8714 and the maximal Youden index was 0.681 at an optimal cutoff S/CO ratio value of 8.99. Conclusions With the cutoff value of 1.0, the Architect anti-HCV assay showed excellent sensitivity but poor specificity in predicting HCV viremia. An S/Co ratio of 8.99 was optimal for further confirmation testing of HCV viremia.

Background The Daan HCV RNA quantitative assay was a recently developed kit with high sensitivity for the detection of HCV RNA. We aimed to evaluate the analytical performance of the Daan HCV RNA quantitative assay and compare it with the COBAS AmpliPrep/COBAS TaqMan HCV Quantitative Test, v2.0. Method WHO HCV RNA standard, NIBSC 06/102 standard, and CLSI EP documents were used to evaluate the precision, accuracy, linearity, anti-interference ability, and cross-reactivity of the Daan HCV RNA quantitative assay. Overall 198 clinical serum specimens were used to make comparison between the Daan HCV RNA quantitative assay and the Roche Cobas test. Results The within-run precision (Swithin ), and total precision (Stotal ) for 6.11 log IU/mL, 4.22 log IU/mL, and 2.32 log IU/mL HCV RNA were 0.13 and 0.15, 0.07 and 0.09, and 0.11 and 0.10, respectively. The linear range was 20-108 IU/mL, and the limit of detection was 15 IU/mL. It did not display any interference with commonly encountered conditions and cross-reactivity with some common virus. A good agreement was observed between the Daan HCV RNA quantitative assay and the Roche Cobas test. Conclusion The Daan HCV RNA quantitative assay has shown satisfactory performances and excellent agreement with COBAS HCV Quantitative Test on clinical specimens with lower cost, which provides an alternative choice for the diagnosis and monitoring of HCV infection in developing countries.

Background: Proper management of patients with chronic hepatitis B virus (HBV) infection requires monitoring of plasma or serum HBV DNA levels using a highly sensitive nucleic acid amplification test. Because commercially available assays differ in performance, we compared herein the performance of the Hologic Aptima HBV Quant assay (Aptima) to that of the Roche Cobas TaqMan HBV test for use with the high pure system (HPS/CTM). Methods: Assay performance was assessed using HBV reference panels as well as plasma and serum samples from chronically HBV-infected patients. Method correlation, analytical sensitivity, precision/reproducibility, linearity, bias and influence of genotype were evaluated. Data analysis was performed using linear regression, Deming correlation analysis and Bland-Altman analysis. Results: Agreement between the assays for the two reference panels was good, with a difference in assay values vs. target 2>0.98). The two assays had similar bias and precision across the different genotypes tested at low viral loads (25–1000 IU/mL). Conclusions: Aptima has a performance comparable with that of HPS/CTM, making it suitable for use for HBV infection monitoring. Aptima runs on a fully automated platform (the Panther system) and therefore offers a significantly improved workflow compared with HPS/CTM.

Background The new Roche Cobas 6800 platform (C6800) has been recently introduced for viral load (VL) measurement. Objectives Comparing C6800 to Cobas Ampliprep/Cobas TaqMan v2.0 (CAP/CTM) for the quantification of HIV, HBV and HCV viremia, and to the Abbott RealTime assay (ABB) for HCV quantification. Study design We analysed 121 samples for HBV, and 139 for HIV-1 including 2 groupO and 137 group M viruses (36.5% subtype B, 27.0% CRF02_AG, 22.6% from other clades, and 14% subtype not available). For the 100 HCV samples compared with CAP/CTM, 42% were genotype 1 and 17% were genotype 4. For the 68 HCV samples compared with ABB, 52.9% were genotype 1 and 22.1% were genotype 4. Results C6800 results correlated well with those of CAP/CTM for all three viruses (R2: 0.97–0.99). However, C6800 can yield different viraemia results: higher for HIV (mean difference: +0.11 log10 copies/mL, p Conclusion Overall, the comparison tests between C6800 and CAP/CTM systems are satisfactory for the three viruses. Frequent discrepancies were observed between C6800 and ABB for HCV.

Background Hepatitis B viral load testing is essential to treatment and monitoring decisions in patients with chronic Hepatitis B. Beckman Coulter has developed the VERIS HBV Assay (Veris) for use on the fully automated DxN VERIS Molecular Diagnostics System. 1 Objectives To evaluate the clinical performance of the Veris HBV Assay at multiple EU laboratories Study design Method comparison was performed with a total of 344 plasma specimens from HBV infected patients tested with Veris and COBAS® TaqMan® HBV Test (Cobas), 207 specimens tested with Veris and RealTime HBV Assay (RealTime), 86 specimens tested with Veris and VERSANT® HBV Assay (Versant), and 74 specimens tested with Veris and artus® HBV RG PCR kit (artus). Results Bland-Altman analysis showed average bias of −0.46 log10 IU/mL between Veris and Cobas, −0.46 log10 IU/mL between Veris and RealTime, −0.36 log10 IU/mL between Veris and Versant, and −0.12 log10 IU/mL between Veris and artus. Bias was consistent across the assay range. Patient monitoring results using Veris demonstrated similar viral load trends over time to Cobas, RealTime, and artus. Conclusions The VERIS HBV Assay demonstrated comparable clinical performance, with varying degrees of negative bias, compared to other currently marketed assays for HBV DNA monitoring. This negative bias should be taken into consideration if switching monitoring methods to Veris.

This study evaluated the use of dried blood spot (DBS) for HCV viral load quantification using the COBAS® AmpliPrep/COBAS® Taqman® HCV Quantitative Test v2.0 (CAP/CTM HCV v2), and compared two different procedures for preparation of DBS samples with a Specimen Pre-Extraction (SPEX) reagent (either heated [SPEX with SH] for 10min at 56°C on a thermomixer, or incubated for 1h at room temperature [SPEX at RT]) against the standard plasma input. Whole blood specimens from 48 patients with chronic HCV infection and Whatman® 903 Protein Saver Cards were used to prepare 35μL DBS. An aliquot of plasma was spun and frozen from each draw. Mean DBS viral load results were compared to the corresponding results from plasma. Correlation between DBS to plasma was linear for both SPEX with SH (R2=0.96) and SPEX at RT (R2=0.97) procedures, with a constant negative offset of approximately 2.0log10IU/mL between whole blood DBS without any adjustments and plasma results. After volume corrections, the mean offset to plasma decreased to -0.39 and -0.36 for the two procedures, respectively. The study demonstrated the use of DBS for HCV viral load correlates well with plasma with a constant offset.

Background Viral load monitoring is essential for patients under treatment for HIV. Beckman Coulter has developed the VERIS HIV-1 Assay for use on the novel, automated DxN VERIS Molecular Diagnostics System.¥ Objectives Evaluation of the clinical performance of the new quantitative VERIS HIV-1 Assay at multiple EU laboratories. Study design Method comparison with the VERIS HIV-1 Assay was performed with 415 specimens at 5 sites tested with COBAS® AmpliPrep/COBAS® TaqMan® HIV-1 Test, v2.0, 169 specimens at 3 sites tested with RealTime HIV-1 Assay, and 202 specimens from 2 sites tested with VERSANT HIV-1 Assay. Patient monitoring sample results from 4 sites were also compared. Results Bland-Altman analysis showed the average bias between VERIS HIV-1 Assay and COBAS HIV-1 Test, RealTime HIV-1 Assay, and VERSANT HIV-1 Assay to be 0.28, 0.39, and 0.61 log10 cp/mL, respectively. Bias at low end levels below 1000 cp/mL showed predicted bias to be Conclusions The VERIS HIV-1 Assay for use on the DxN VERIS System demonstrated comparable clinical performance to COBAS® HIV-1 Test, RealTime HIV-1 Assay, and VERSANT HIV-1 Assay.

Background HIV-RNA is the most important parameter for monitoring antiviral treatment in individuals infected with HIV-1. Knowledge of the performance of different tests for the quantification of HIV-1 RNA is therefore important for clinical care. Objectives To compare the analytical performance of the Aptima HIV-1 Quant Dx Assay (Aptima) and the COBAS Ampliprep/COBAS TaqMan HIV-1 Test v2.0 (CAPCTMv2) for the quantification of HIV-1 RNA in plasma samples. Study design The performance of the two tests was compared on 216 clinical plasma samples, on dilutions series in seven replicates of five clinical samples of known subtype and on ten replicates of the Acrometrix High and Low Positive Control. Results Bland-Altman analysis of 130 samples that quantified in both tests did not show indications of gross mis-quantification of either test. A tendency of the Aptima assay to quantify higher at high viral load compared to the CAPCTMv2 was observed in Bland-Altman analysis, by Deming regression (Slope 1.13) and in dilution series of clinical samples. Precision evaluated using the Acrometrix Positive Controls was similar for the High Control (CV: 1.2% vs. 1.3%; Aptima assay vs. CAPCTMv2 test, respectively), but differed for the Low control (CV: 17.9% vs. 7.1%; Aptima assay vs. CAPCTMv2 test, respectively). However, this did not impact clinical categorization of clinical samples at neither the 50 cp/mL nor 200 cp/mL level. Conclusion The Aptima assay and the CAPCTMv2 test are highly correlated and are useful for monitoring HIV-infected individuals.

Background Beckman Coulter has developed the VERIS HCV Assay for use on the new fully automated DxN VERIS Molecular Diagnostic System¥ for HCV viral load monitoring. Objectives Evaluate the clinical performance of the new quantitative VERIS HCV Assay. Study design Comparison was performed on 279 plasma specimens from HCV infected patients tested with the VERIS HCV Assay and COBAS® Ampliprep/COBAS® Taqman® HCV Test and 369 specimens tested with the VERIS HCV Assay and RealTime HCV Assay. Patient monitoring sample results from four time points were also compared. Results The average bias between the VERIS HCV Assay and the COBAS® Ampliprep/COBAS® Taqman® HCV Test was 0.04 log10 IU/mL, while between the VERIS HCV Assay and the RealTime HCV Assay average bias was 0.21 log10 IU/mL. Bias, however, was not consistent across the measuring range. Analysis at the lower end of quantification levels 50, 100, and 1000 IU/mL showed a predicted bias for VERIS HCV Assay versus COBAS® Ampliprep/COBAS® Taqman® HCV Test between −0.42 and −0.22 log10 IU/mL and for VERIS HCV Assay versus RealTime HCV Assay between 0.00 and 0.13 log10 IU/mL. Patient monitoring of HCV viral load over time demonstrated similar levels between VERIS HCV Assay results and COBAS® Ampliprep/COBAS® Taqman® HCV Test (52 samples from 13 patients) and RealTime HCV Assay (112 samples from 28 patients). Conclusions VERIS HCV Assay for use on the DxN VERIS Molecular Diagnostic System represents a reliable new tool for easy sample to result HCV RNA viral load monitoring.

Sir,In the present journal, an evaluation of Cobas TaqMan MTB test for the detection of Mycobacterium tuberculosis complex on various clinical specimens was presented [1]. Based on culture as refer...

Background Early infant diagnosis (EID) of HIV-1 exposed infants enables timely initiation of antiretroviral therapy (ART), thereby allowing early diagnosis and treatment to slow disease progression and reduce mortality. Turn-around time to results, partially caused by low to medium throughput technology, remains a hindrance to early treatment. A major solution to this challenge is to incorporate high throughput and accurate technologies in the testing process. The Hologic Aptima Quant Dx Assay (Aptima) is a CE marked Real-Time TMA assay running on the high throughput Panther system. Objectives The objective of this study was to evaluate the performance of Aptima for EID using dried blood spots. Study design This was a cross-sectional prospective study of 2,048 infants seeking HIV services from health facilities in Western Kenya, Africa. Capillary Dried Blood Spot samples DBS were collected from infants with the consent of their mothers. The qualitative performance of Aptima was compared with the Roche COBAS Ampliprep/ COBAS Taqman HIV-1 Qualitative Test v2.0 (CAP/CTM), using these DBS. Demographic information of the participants was also collected. Results A total of 1,975 successful comparisons between the two platforms were included in the analysis. The overall agreement between the assays was 99.65 %. The sensitivity and specificity of Aptima was 95.24 % (95 % CI 88.40–98.19 %) and 99.84 % (95 % CI 99.49–99.92 %) respectively. Conclusions Aptima assay has performance characteristics that are comparable to those of the Roche CAP/CTM for qualitative testing on DBS taken from infants. The two assays can therefore be used interchangeably for Early Infant Diagnosis of HIV.

Objectives To compare quantified human immunodeficiency virus type 1 (HIV-1) viral load quantified using the cobas HIV-1 test with that obtained using the CAP/CTM HIV-1 and Abbott RealTime HIV-1 tests and evaluate the performance of cobas HIV-1 using the cobas 4800 system. Methods Clinical samples (n = 123) were quantitatively analyzed using the CAP/CTM HIV-1, Abbott RealTime HIV-1, and cobas HIV-1 tests, and the precision, linearity, and limit of detection of the cobas HIV-1 test were evaluated. Results Comparable results were obtained by both methods: ([log CAP/CTM HIV-1 value] = 0.979 * [log cobas HIV-1 test value] + 0.034) and ([log Abbott RealTime HIV-1 value] = 0.985 * [log cobas HIV-1 test value] + 0.027). cobas HIV-1 test results for 89.4% and 93.5% were within 0.5 log10 IU/mL of the CAP/CTM HIV-1 and Abbott RealTime HIV-1 results, respectively. Conclusions The cobas HIV-1 test showed good performance, and its results correlated well with those of other two tests.

The Roche Cobas AmpliPrep/Cobas TaqMan HIV-1 test, v2.0 (the CAP/CTM assay), was used to quantify cell-associated HIV-1 (CAH) nucleic acid in peripheral blood mononuclear cells (PBMC) from well-characterized clinical specimens from HIV-1-infected individuals on antiretroviral therapy (ART). Chronically infected individuals on ART with no detectable plasma HIV-1 RNA demonstrated average CAH burdens of 3.2 HIV-1 log(10) copies/million cells. Assay sensitivity and specificity were 98.9% and 100%, respectively, with the positive and negative predictive values being 100% and 98.6%, respectively. The CAH burden was also measured at weeks 0, 1, 2, 8, and 60 in 37 participants (RV254/SEARCH010, Bangkok, Thailand) stratified by Fiebig stage (Fiebig stage I [FI] to FVI) at ART initiation. Prior to ART initiation, the average CAH burden was 1.4, 4.1, and 3.6 log(10) copies/million PBMCs for individuals who initiated ART at FI, FII, and FIII to FVI, respectively. Initiation of ART resulted in a rapid decline of CAH in all individuals, with the greatest decrease being observed in individuals who initiated ART at FI to FIII. By week 60, 100% (FI), 71.8% (FII/FIII), and 20.5% (FIV to FVI) of samples from individuals initiating treatment were at or near the limit of quantitation. Residual CAH was detectable at 60 weeks in most individuals who initiated ART at later stages (FIV to FVI) and averaged 1.9 ± 0.7 log(10) copies/million PBMCs. The modified Roche CAP/CTM assay provides a convenient, standardized approach to measure residual HIV in blood and may be useful for monitoring patients under therapy or those participating in HIV remission studies.

Background Implementation of affordable methods for HCV viremia is a key priority for identifying individuals who need treatment among persons screened positive for HCV antibodies. Different HCV PCR assays for use on open polyvalent PCR platforms are currently commercially available but studies evaluating the performances of these nucleic acid tests are needed. Objectives In the present study, we evaluated the analytical and clinical performances of a recently developed HCV RNA PCR assay for detection and quantification of HCV viremia. Study design In this study the Biocentric Generic HCV PCR was compared to the Roche Cobas AmpliPrep/Cobas TaqMan HCV RNA assay. Analytical and clinical performances was evaluated on reference materials and HCV plasma samples collected in 141 patients attending at the Montpellier University Hospital in France. Field evaluation was performed on samples collected in 185 patients attending at Medical Laboratory, Institut Pasteur in Cambodia. Results The lower limit of detection ranged from 50 HCV RNA IU/ml to 300 HCV RNA IU/ml using four different Diasorin and Qiagen automated or manual extraction methods. The specificity (CI) and sensitivity of the assay were 100% (92.5–100), and 98.7% (92.3–99.9), respectively, in France, and 100% (95.5–100), and 100% (94.4–100%), respectively, in Cambodia. Bland–Altman analysis shown good agreement between the two assays including for genotypes 6 HCV, which represent the majority of HCV isolates in Cambodia. Conclusions The Biocentric Generic HCV assay has shown overall satisfactory analytical performances and a close agreement to the Cobas HCV assay on clinical specimens collected in France and Cambodia. There is an urgent need to further evaluate commercial assays dedicated to HCV detection and quantification using open polyvalent PCR platforms in different settings.

Quantitation of the HIV-1 viral load in plasma is the current standard of care for clinical monitoring of HIV-infected individuals undergoing antiretroviral therapy. This study evaluated the analytical and clinical performances of the Aptima HIV-1 Quant Dx assay (Hologic, San Diego, CA) for monitoring viral load by using 277 well-characterized subtype samples, including 171 cultured virus isolates and 106 plasma samples from 35 countries, representing all major HIV subtypes, recombinants, and circulating recombinant forms (CRFs) currently in circulation worldwide. Linearity of the Aptima assay was tested on each of 6 major HIV-1 subtypes (A, B, C, D, CRF01_AE, and CRF02_AG) and demonstrated an R 2 value of ≥0.996. The performance of the Aptima assay was also compared to those of the Roche COBAS AmpliPrep/COBAS TaqMan HIV-1 v.2 (CAP/CTM) and Abbott m2000 RealTime HIV-1 (RealTime) assays on all subtype samples. The Aptima assay values averaged 0.21 log higher than the CAP/CTM values and 0.30 log higher than the RealTime values, and the values were >0.4 log higher than CAP/CTM values for subtypes F and G and than RealTime values for subtypes C, F, and G and CRF02_AG. Two samples demonstrated results with >1-log differences from RealTime results. When the data were adjusted by the average difference, 94.9% and 87.0% of Aptima results fell within 0.5 log of the CAP/CTM and RealTime results, respectively. The linearity and accuracy of the Aptima assay in correctly quantitating all major HIV-1 subtypes, coupled with the completely automated format and high throughput of the Panther system, make this system well suited for reliable measurement of viral load in the clinical laboratory.

Background:Several commercially available molecular techniques were developed based on subtype B of HIV-1, which represents only 10% of HIV strains worldwide. Indeed, in sub-Saharan Africa, non-B subtypes of HIV-1 are predominant. The aim of this study was to evaluate the performances of the COBAS®AmpliPrep/COBAS®(CAP/CTM) HIV-1 Qualitative assays to detect the broad range of HIV-1 variants circulating in Central Africa and compare to the outgoing CAP/CTM HIV-1 Quantitative test v2.0 (Roche Molecular Systems), chosen as reference gold standard molecular assay.Methods:The CAP/CTM HIV-1 Qualitative tests versions 1.0 and 2.0 (Roche Molecular Systems, Inc., Branchburg, NJ, USA) were evaluated compared to CAP/CTM TaqMan HIV-1 Quantitative test v2.0 (Roche Molecular Systems) on 239 dried plasma spot (DPS) from 133 HIV-1-infected (with detectable plasma HIV RNA load) and 106 uninfected children, followed-up at Complexe Pédiatrique, Bangui, Central African Republic.Results:The version 1.0 showed low sensitivity (93.2%), with 9 (6.8%) false negative results, demonstrating under-detection of non-B HIV-1 subtypes. In contrast, the upgraded version 2.0 showed 100%-sensitivity, 100%-specificity and perfect agreement (κ coefficient, 1.0).Conclusion:Our evaluation in the Central African Republic demonstrates the clinical implications of the accuracy and reliability of the CAP/CTM HIV-1 Qualitative assay for early diagnosis of HIV-1 in Central African children.

Background Cepheid's Xpert HIV‐1 Viral Load (Xpert VL), a simplified, automated, single-use quantitative assay used with the GeneXpert System, is not FDA approved. Objectives Using stored plasma, we conducted a study to assess the ability of Xpert VL to quantify viral load relative to the Roche COBAS AmpliPrep/COBAS TaqMan HIV-1 (Cobas VL) and to examine the use of the Xpert VL as a qualitative diagnostic test. Study design Following HIV-1 viral stock dilutions, we conducted a probit analysis to identify the concentration where 95 % of specimens had quantified VLs. We also examined Xpert and Cobas log VL correlation in linearity panels; compared the proportion of 220 seroconverter specimens with virus detected using McNemar's test; and tested specimens from persons with untreated, established HIV-1 infection (n=149) and uninfected persons (n=497). Furthermore, we examined Xpert VL as a qualitative test in seroconverter specimens with early (n=20) and later (n=68) acute infections. Results At 1.80 log10 copies/mL, 95 % of specimens had quantifiable virus using Xpert VL. Xpert and Cobas VLs were highly correlated (R2=0.994). The proportion of seroconverter specimens with virus detected using Cobas and with Xpert VL was not statistically different (p=0.0578). Xpert VL detected 97.9 % of established infections, and specificity was 99.80 % (95 % CI 98.87%–99.99%). Xpert VL detected 90 % and 98.5 % of early and later acute infections, respectively. Conclusions If approved, Xpert VL could allow U.S. laboratories that cannot bring on large, complex testing platforms to conduct HIV monitoring. An approval for diagnostic use may provide timely identification of HIV infections.

Background: Hepatitis B virus (HBV) nucleic acid amplification testing (NAAT) is important for the diagnosis and management of HBV infection. We evaluated the analytical performance of the cobas HBV NAAT (Roche Diagnostics GmbH, Mannheim, Germany) on the cobas 4800 System in comparison with COBAS AmpliPrep/COBAS TaqMan HBV Test (CAP/CTM HBV). Methods: Precision was evaluated using three levels of cobas HBV/HCV/HIV-1 Control Kit, and linearity was evaluated across the anticipated measuring range (10.0–1.0×109 IU/mL) at seven levels using clinical samples. Detection capability, including limit of blank (LOB), limit of detection (LOD) and limit of quantitation (LOQ), was verified using the 4th WHO International Standard for HBV DNA for NAT (NIBSC code: 10/266). Correlation between the two systems was compared using 205 clinical samples (102 sera and 103 EDTA plasma). Results: Repeatability and total imprecision (coefficient of variation) ranged from 0.5% to 3.8% and from 0.5% to 3.5%, respectively. Linearity (coefficient of determination, R2) was 0.999. LOB, LOD and LOQ were all acceptable within the observed proportion rate (85%). Correlation was very high between the two systems in both serum and plasma samples (correlation coefficient [r]=0.995). Conclusions: The new cobas HBV real-time PCR assay on the cobas 4800 System showed reliable analytical performances.

Background Quantification of HBV DNA is used for initiating and monitoring antiviral treatment. Analytical test performance consequently impacts treatment decisions. Objectives To compare the analytical performance of the Aptima HBV Quant Assay (Aptima) and the COBAS Ampliprep/COBAS TaqMan HBV Test v2.0 (CAPCTMv2) for the quantification of HBV DNA in plasma samples. Study design The performance of the two tests was compared on 129 prospective plasma samples, and on 63 archived plasma samples of which 53 were genotyped. Linearity of the two assays was assessed on dilutions series of three clinical samples (Genotype B, C, and D). Results Bland-Altman analysis of 120 clinical samples, which quantified in both tests, showed an average quantification bias (Aptima – CAPCTMv2) of −0.19 Log IU/mL (SD: 0.33 Log IU/mL). A single sample quantified more than three standard deviations higher in Aptima than in CAPCTMv2. Only minor differences were observed between genotype A (N = 4; average difference −0.01 Log IU/mL), B (N = 8; −0.13 Log IU/mL), C (N = 8; −0.31 Log IU/mL), D (N = 25; −0.22 Log IU/mL), and E (N = 7; −0.03 Log IU/mL). Deming regression showed that the two tests were excellently correlated (slope of the regression line 1.03; 95% CI: 0.998-1.068). Linearity of the tests was evaluated on dilution series and showed an excellent correlation of the two tests. Both tests were precise with %CV less than 3% for HBV DNA ≥3 Log IU/mL. Conclusions The Aptima and CAPCTMv2 tests are highly correlated, and both tests are useful for monitoring patients chronically infected with HBV.

The aim of the present study was to evaluate the performance of three in-house PCR techniques for HBV DNA detection and compare it with commercial quantitative methods to evaluate the usefulness of in-house methods for HBV diagnosis. Three panels of HBsAg reactive sera samples were evaluated: (i) 50 samples were examined using three methods for in-house qualitative PCR and the Cobas Amplicor HBV Monitor Assay; (ii) 87 samples were assayed using in-house semi-nested PCR and the Cobas TaqMan HBV test; (iii) 11 serial samples obtained from 2 HBV-infected individuals were assayed using the Cobas Amplicor HBV test and semi-nested PCR. In panel I, HBV DNA was detected in 44 samples using the Cobas Amplicor HBV test, 42 samples using semi-nested PCR (90% concordance with Cobas Amplicor), 22 samples using PCR for the core gene (63.6% concordance) and 29 samples using single-round PCR for the pre-S/S gene (75% concordance). In panel II, HBV DNA was quantified in 78 of the 87 HBsAg reactive samples using Cobas TaqMan but 52 samples using semi-nested PCR (67.8% concordance). HBV DNA was detected in serial samples until the 17th and 26th week after first donation using in-house semi-nested PCR and the Cobas Amplicor HBV test, respectively. In-house semi-nested PCR presented adequate concordance with commercial methods as an alternative method for HBV molecular diagnosis in low-resource settings.

The aim of this study was to compare four HIV-1 viral quantitation platforms, Nuclisens EasyQ v2.0 ® (EQ), COBAS AmpliPreP/Cobas Taqman ® HIV-1 test v 2.0 (CTM), GENERIC HIV CHARGE VIRALE ® (GEN), with Abbott Real Time HIV-1 ® (m2000sp/rt) as reference technique. The study had first evaluated m2000sp/rt performances and then compared quantitation between techniques. Discordant samples were genotyped on gag and pol gene and sequences were analyzed using Sequence locator and SeqPublish to detect eventual mismatches. Performance analysis of m2000sp/rt showed good results with coefficients of variation values (CV) of 1.35%, 0.65%, and 0.54% for repeatability testing of low, intermediate and high concentrations, respectively. Reproducibility tests showed low CV values with 2.36% and 1.42% for low and high concentration levels, respectively and contamination test was very low value with 0.94%. Correlation and concordance between techniques ranged from r 2 = 0.98 and bias = −0.00185 (for m 2000sp/rt vs CTM) to r 2 = 0.90 and bias = −0.135 (for EQ vs GEN). Discrepancies were observed on 37 samples mostly CRF02_AG but despite some mismatches, sequence analysis (26/37) did not show any remarkable differences between CRF02_AG queries and references. This study showed good correlation and good concordance between techniques. However, EQ yielded under-quantitation of CRF02_AG.

Background: Improved viral detections by the real time PCR over the manual assays have been reported by various manufacturers. However, discrepancies and discordance between different platforms targeting the same pathogen have also been observed at different settings. Methods: We used an analytical study design to compare the performance of the Cobas Taqman /Cobas Ampliprep version 2.0 against the standard Amplicor Monitor 1.5 using 200 routine clinical samples, in Abuja- Nigeria. Results: Taqman and Amplicor detected 118/200 (59%) and 83/200 (41.5%) samples respectively. Two of 83 samples (2.4%) undetectable by Cobas Taqman, were detectable by Roche Amplicor, while 5 of 37 samples (13.5%) which were undetectable by Amplicor using Taqman. Among the 81 detectable samples by both assays 4 samples (4.9%) had a log10 difference > 0.5 log copies, while 9 samples (11.1%) showed a wider discrepancy of >1 log10. Bland and Altman’s comparison shows no significant difference between the two methods (p=0.2825) and CI-0.06171 to 0.2087. Conclusion: We observed a remarkable improvement in the performance of COBAS AmpliPrep/COBAS TaqMan version 2.0 Assay over Amplicor Monitor version 1.5 in the quantification of HIV1 RNA viral load. Discrepancies of clinical significance, in the viral load between the two platforms were also recorded. The implications of the inability of the automated Taqman 2.0 to detect 2.4% of samples detectable by the Amplicor need to be considered by programs, clinicians and the manufacturers. Periodic evaluation of platforms to detect new circulating HIV subtypes within each locality is also recommended.

Background: Accurate quantitation of plasma Human immunodeficiency virus-1 (HIV) RNA levels is required for clinical management of HIV-1-infected patients. Several assays are used to quantify HIV RNA, and prior to implementing a change in viral load method, continuity in reported values is addressed by the laboratory and communicated to clinicians. Methods: We initially compared COBAS® AmpliPrep-COBAS® TaqMan 48 (TaqMan) v.1.0 (Roche) to prior methodology, branched-chain DNA (bDNA) v.3.0 (Siemens) to determine if establishment of new patient baselines were necessary. Study data from 81 specimens run by both assays were compared using nonparametric tests, e.g., Wilcoxon signed-rank, Spearman. Subsets for comparison included only those that fell into overlapping ranges for both assays. Results: The methods correlated (Spearman correlation, rs = 0.91), but TaqMan values were significantly higher than those of bDNA (p Conclusion: Our data demonstrate non-equivalence in HIV-1 RNA values of TaqMan v.1.0 as compared to bDNA v.3.0, and that new baselines for HIV viral load RNA HIV-1 should be re-established. New baselines for those patients missed by parallel testing can be calculated using regression analysis.

Roche modified the COBAS AmpliPrep/COBAS TaqMan human immunodeficiency virus type 1 (HIV-1) test version 1.0 (CAP/CTM v1.0), resulting in the COBAS AmpliPrep/COBAS TaqMan HIV-1 test version 2.0 (CAP/CTM v2.0). The aim of this study was to evaluate the performance of the CAP/CTM v2.0 and to compare this performance with that of the CAP/CTM v1.0. The study was conducted in a small local study group in Kaohsiung Medical University Hospital, Kaohsiung, Taiwan. A total of 86 plasma samples from HIV-1-seropositive patients were tested using the two assays. The correlation and concordance of results between the two assays were calculated. The CAP/CTM v2.0 generated higher values than did the CAP/CTM v1.0, and five samples (5.8%) yielded a difference of > 1 log10 copies/mL. In addition, our data show that CAP/CTM v1.0 and CAP/CTM v2.0 yielded relatively consistent values for 23 samples with low viral loads (< 200 copies/mL). Furthermore, when viral loads were in a medium range (2–5 log10 copies/mL), the results of the two assays were more compatible. This study shows a good correlation between CAP/CTM v1.0 and v2.0 in HIV-1 viral load measurement. Further attention must be paid to those cases in which measured viral loads present larger differences between the two assays.

The AdvanSure tuberculosis/non-tuberculous mycobacterium (TB/NTM) PCR (LG Life Science, Korea) and COBAS TaqMan Mycobacterium tuberculosis (MTB) PCR (Roche Diagnostics, USA) are commonly used in clinical microbiology laboratories. We aimed to evaluate these two commercial real-time PCR assays for detection of MTB in a large set of clinical samples over a two-year period. AdvanSure TB/NTM PCR and COBAS TaqMan MTB PCR were performed on 9,119 (75.2%) and 3,010 (24.8%) of 12,129 (9,728 respiratory and 2,401 non-respiratory) MTB specimens, with 361 (4.0%) and 102 (3.4%) acid-fast bacilli (AFB)-positive results, respectively. In MTB culture, 788 (6.5%) MTB and 514 (4.2%) NTM were identified. The total sensitivity and specificity of the AdvanSure assay were 67.8% (95% confidence interval [CI], 63.9-71.6) and 98.3% (95% CI, 98.0-98.6), while those of the COBAS TaqMan assay were 67.2% (95% CI, 60.0-73.8) and 98.4% (95% CI, 97.9-98.9), respectively. The sensitivities and specificities of the AdvanSure and COBAS TaqMan assays for AFB-positive and AFB-negative samples were comparable. Furthermore, the AdvanSure assay showed fewer invalid results compared with the COBAS TaqMan assay (5.0 vs. 20.4 invalid results/1,000 tests, P

Aim: The study aimed to evaluate the clinical utility of the chemiluminescent HCV core Ag test compared to viral load assessment in the management of patients with chronic hepatitis C.Methods: A retrospective study was performed at a tertiary-care infectious diseases hospital on samples collected from anti-HCV positive patients. Seventy-six samples were tested with the Architect HCV core Antigen kit and Cobas AmpliPrep/Cobas Taqman HCV kit. The HCV Ag test accuracy was estimated using data from all the HCV RNA tested samples received between January 2011 and December 2012.Results: The HCV Ag test showed a good correlation between the logarithmic values of HCV RNA and HCV Ag (R=0.98), with a 100% specificity and PPV, but with reduced sensitivity for viral loads lower than 1,000 UI/ mL. In a model using data from 2,478 HCV RNA tested samples and a cut-off of the Ag assay corresponding to 1,000 UI/mL HCV RNA, the Ag test would have a sensitivity of 82.4%, a NPV of 80.9% and a high specificity and PPV (100%) compared to the viral load. The sensitivity would be higher for baseline evaluation compared to on-treatment samples (98.5 vs. 50%). The highest NPV (98%) would be obtained at 48 and 72 weeks after the initiation of treatment, with a sensitivity of 88.2% and 96.1%, respectively.Conclusion: The Architect HCV core Ag assay might be an alternative for the diagnosis of active HCV infection if molecular tests are not available, and a useful method for the evaluation of sustained virological response in treated patients.

Background Hepatitis B virus (HBV) DNA levels are used to predict the response to therapy, determine therapy initiation, monitor resistance to therapy, and establish treatment success. Objective To verify the performance of the cobas HBV test using the cobas 4800 system for HBV DNA quantification and to compare the HBV DNA quantification ability between the cobas HBV test and COBAS AmpliPrep/COBAS TaqMan HBV version 2.0 (CAP/CTM v2.0). Study design The precision, linearity, and limit of detection of the cobas HBV test were evaluated using the 4th World Health Organization International Standard material and plasma samples. Clinical samples that yielded quantitative results using the CAP/CTM v2.0 and cobas HBV tests were subjected to correlational analysis. Results Three hundred forty-nine samples were subjected to correlational analysis, among which 114 samples showed results above the lower limit of quantification. Comparable results were obtained ([cobas HBV test] = 1.038 × [CAP/CTM v2.0]–0.173, r = 0.914) in 114 samples, which yielded values above the lower limit of quantification. The results for 86.8% of the samples obtained using the cobas HBV test were within 0.5 log10 IU/mL of the CAP/CTM v2.0 results. The total precision values against the low and high positive controls were 1.4% (mean level: 2.25 log10 IU/mL) and 3.2% (mean level: 6.23 log10 IU/mL), respectively. The cobas HBV test demonstrated linearity (1.15–6.75 log10 IU/mL, y = 0.95 × 6 + 0.17, r2 = 0.994). Conclusion The cobas HBV test showed good correlation with CAP/CTM v2.0, and had good precision and an acceptable limit of detection. The cobas HBV test using the cobas 4800 is a reliable method for quantifying HBV DNA levels in the clinical setting.

BACKGROUND Measurement of viral load in human immunodeficiency virus type 1 (HIV-1) infected patients is essential for the establishment of a therapeutic strategy. Several assays based on qPCR are available for the measurement of viral load; they differ in sample volume, technology applied, target gene, sensitivity and dynamic range. The Bioneer AccuPower® HIV-1 Quantitative RT-PCR is a novel commercial kit that has not been evaluated for its performance. OBJECTIVE This study aimed to evaluate the performance of the Bioneer AccuPower® HIV-1 Quantitative RT-PCR kit. METHODS In total, 288 EDTA plasma samples from the Dharmais Cancer Hospital were analyzed with the Bioneer AccuPower® HIV-1 Quantitative RT-PCR kit and the Roche COBAS® AmpliPrep/COBAS® TaqMan® HIV-1 version 2.0 (CAP/CTM v2.0). The performance of the Bioneer assay was then evaluated against the Roche CAP/CTM v2.0. RESULTS Overall, there was good agreement between the two assays. The Bioneer assay showed significant linear correlation with CAP/CTM v2.0 (R2=0.963, p

An accurate quantification of low viremic HCV RNA plasma samples has gained importance since the approval of direct acting antivirals and since only one single measurement predicts the necessity of a prolonged or shortened therapy. As reported previously, HCV quantification assays such as Abbott RealTime HCV and Roche COBAS AmpliPrep/COBAS TaqMan HCV version 2 (CTM v2) may vary in sensitivity and precision particularly in low-level viremia. Importantly, substantial variations were previously demonstrated between some of these assays compared to the Roche High Pure System/COBAS TaqMan assay (HPS) reference assay, which was used to establish the clinical decision points in clinical studies. In this study, the reproducibility of assay performances across several laboratories was assessed by analysing quantification results generated by six independent laboratories (3× RealTime, 3× CTM v2) in comparison with one HPS reference laboratory. The 4th WHO Standard was diluted to 100, 25 and 10 IU/ml, and aliquots were tested in triplicates in 5 independent runs by each assay in the different laboratories to assess assay precision and detection rates. In a second approach, 2 clinical samples (GT 1a & GT 1b) were diluted to 100 and 25 IU/ml and tested as described above. While the result range for WHO 100 IU/ml replicates across all laboratories was similar in this analysis, the CVs of each laboratory ranged from 19.3 to 25.6 % for RealTime laboratories and were lower than CVs of CTM v2 laboratories with a range of 26.1-47.3 %, respectively, and also in comparison with the CV of the HPS reference laboratory (34.9 %). At WHO standard dilution of 25 IU/ml, 24 replicates were quantified by RealTime compared to 8 replicates with CTM v2. Results of clinical samples again revealed a higher variation of CTM v2 results as compared to RealTime values. (CVs at 100 IU/ml: RealTime: 13.1-21.0 % and CTM v2: 15.0-32.3 %; CVs at 25 IU/ml: RealTime 17.6-34.9 % and CTM v2 28.2-54.9 %). These findings confirm the superior precision of RealTime versus CTM v2 at low-level viremia even across different laboratories including the new clinical decision point at 25 IU/ml. A highly precise monitoring of HCV viral load during therapy will remain crucial for patient management with regard to futility rules, therapy efficacy and SVR. CA extern

BACKGROUND Differences between the designs of hepatitis C virus (HCV) viral load assays can result in genotype-related variability in RNA quantification. We tested paired aliquots of plasma specimens from HCV-infected individuals using two versions (v1.0 and v2.0) of the Roche COBAS AmpliPrep/COBAS TaqMan HCV Test (CAP/CTM HCV) and noted variability between results for a subset of specimens; we then sought to determine whether discrepant results were more prevalent among specific HCV genotypes. METHODS Archived and prospectively-collected plasma samples from 114 unique patients were tested using CAP/CTM HCV v1.0 and v2.0. The HCV genotype result for each patient was determined by retrospectively reviewing laboratory records. RESULTS All (46/46) specimens with quantifiable viral loads from patients with genotype 1 or 2 infection had CAP/CTM HCV v1.0 and v2.0 results that were within 0.5 log10 IU/mL; in contrast, only 3/11 (27.3%) from patients with HCV genotype 3 (mean difference, 0.56 log10 IU/mL higher with v2.0) and 0/3 (0%) from patients with HCV genotype 4 (mean difference, 0.91 log10 IU/mL higher with v2.0) had results within 0.5 log10 IU/mL. Among specimens with detectable HCV RNA below the lower limit of quantification with v1.0, greater proportions of genotype 3 (4/7, 57.1%) and genotype 4 (3/4, 75.0%) specimens than genotype 1 or 2 specimens (6/30, 20.0%) had v2.0 results within the quantifiable range. CONCLUSIONS In patients infected with HCV genotype 3, sequential CAP/CTM HCV viral load results should be compared with caution and interpreted in the context of the specific assay version used.

The COBAS(®) AmpliPrep/COBAS(®) Taqman(®) HCV Quantitative Test, version 2.0, is an in vitro, fully automated, real-time, nucleic acid amplification test indicated for quantifying hepatitis C virus (HCV) RNA levels in the plasma/serum of patients infected with HCV of genotypes 1-6 who are receiving anti-viral therapy. By quantifying levels of HCV RNA in these patients, the test can be used early in the course of treatment to predict the likelihood of a sustained virologic response being achieved and can also be used to assess virologic response during treatment as part of response-guided therapy. The test has excellent sensitivity, high specificity and a broad linear range of quantitation. It correlates well with version 1.0 of the same test, but has the benefit of better sensitivity and genotype inclusivity and a smaller sample input volume. It also correlates well with other available HCV tests, including other quantitative real-time PCR tests (specifically the COBAS(®) Taqman(®) HCV Test, version 2.0, used with the high pure system, and the Abbott Realtime and Artus HCV QS-RGQ tests), the Versant(®) branched DNA quantitative test, the COBAS(®) Amplicor HCV Qualitative PCR Test and the Versant(®) HCV qualitative transcription-mediated amplification assay. The test is not indicated for HCV infection diagnosis or to screen for the presence of HCV in blood/blood products.