Comparison of eMAG™ versus NucliSENS® EasyMAG® performance on clinical specimens

BackgroundeMAG™ (bioMerieux) is a new nucleic acid extraction platform based on magnetic silica technology, like its predecessor, NucliSENS^® easyMAG^® (bioMerieux). Using the same reagents and disposables, eMAG™ adds further automation, allowing simultaneous extraction of 48 samples directly from primary tubes, and distribution of nucleic acid extracts on PCR strips or in tubes at the end of the extraction process.ObjectiveTo compare the performance of eMAG™ and easyMAG^® on various clinical specimens.Study designRespiratory (n = 199), whole blood (n = 50), plasma (n = 25) and urine (n = 25) specimens were extracted in parallel on both platforms. Both qualitative (respiratory virus, cell control, CMV, EBV, HHV6 and BKV detection) and quantitative (respiratory virus and cell control cycle thresolds, and CMV, EBV, HHV6 and BKV viral loads) results were compared.ResultsDetection of qualitative targets showed good agreement, ranging from 84.6% for whole blood to 95.9% for respiratory specimens. Correlations between quantitative results were good, with R² ranging from 0.802 to 0.995. Quantitative results showed average overall differences below 0.10 log₁₀ copies/mL between eMAG™ and easyMAG^®.ConclusionsThe two platforms showed comparable performance on the types of clinical specimen tested. With higher automation and throughput than easyMAG^®, the eMAG™ platform is likely to be advantageous for laboratories performing a large number of molecular analyses.     

Comparison of three real-time PCR for the quantification of polyomavirus BK

BackgroundReactivation of latent polyomavirus BK is associated with nephropathy (PVAN) after renal transplantation. BK viral load determinations are a highly sensitive and specific method for predicting risk for PVAN.Objectives and study designThe performance of three real-time PCR for BKV DNA quantification (MultiCode^®-RTx BK virus ASR [MC-RTx], MGB-Alert BKV ASR [MGB] and a laboratory developed assay [LDA]) were evaluated against a conventional PCR (test of record, TOR) in terms of linearity, dynamic range, and accuracy.ResultsThe LOD (log₁₀ copies/ml) were 2.0, 2.0 and 3.0 for MC-RTx, MGB and LDA, respectively with a commercial plasma panel and 2.0, 2.6 and 3.5 with a urine panel. These assays demonstrated excellent linearity (r² = 1.0) and reproducibility (CV range = 0.7–20.4%, 0.9–13.2%, and 0.5–13%, respectively). In an analysis of 100 clinical specimens, all 76 samples defined as true positive for BKV DNA (positive by two or more methods or a recent history of positivity) were detected with MC-RTx, while only 64 were detected with MGB and 55 were detected with LDA. BKV DNA was not detected by any method in the true negative specimens. Based on these results, the sensitivities were 100% for MC-RTx, 84% for MGB and 72% for LDA. The greatest linear correlation with the mean concentration was observed with MC-RTx (r² = 0.96) with two samples (3%) with greater than 0.5 log₁₀ variance in quantification versus seven (11%) with MGB and ten (18%) with LDA.ConclusionsThese real-time assays for BKV load demonstrated excellent performance characteristics, with the MC-RTx demonstrating the greatest sensitivity.     

CMV antigenemia and quantitative viral load assessments in hematopoietic stem cell transplant recipients

BackgroundSensitive and reliable diagnostic tests are essential for the prevention of cytomegalovirus (CMV) disease after hematopoietic stem cell transplantation (HSCT). pp65 antigenemia and polymerase chain reaction (PCR) assays are commonly used to monitor CMV in HSCT recipients. However, there is considerable intra- and inter-laboratory variability in the results, which impact comparability and clinical practice.Objectives/study designUsing 380 samples from 135 HSCT recipients, we compared the new FDA approved quantitative PCR assay, COBAS^® AmpliPrep/COBAS^® TaqMan^® CMV test (CAP/CTM CMV test) developed and standardized using the 1st WHO International Standard for CMV with pp65 antigenemia and COBAS^® AMPLICOR MONITOR CMV tests.ResultsThe median time between transplantation and testing samples was 57 days (range, 0–207 days). The median CMV load (log₁₀) was 3.17 IU/mL (3.21 copies/mL). Among samples with detectable CMV load, 52% were negative by pp65 antigenemia. CMV loads were higher in pp65 antigenemia-positive than in negative samples. One pp65-antigenemia-positive cell per 100,000 leukocytes corresponded to a median CMV load of 1200 IU/mL. CMV loads determined by the CAP/CTM CMV test were slightly lower than the ones by the AMPLICOR MONITOR CMV test (?0.15 [95% CI, ?0.18 to ?0.13] copies/mL), but slope differences indicated only limited co-linearity.ConclusionsThe CAP/CTM CMV test is more sensitive than pp65 antigenemia and the AMPLICOR MONITOR CMV test in HSCT recipients. The lower limit of quantification and co-linearity with the international WHO standard renders the CAP/CTM CMV test suitable for future clinical trials defining viral load thresholds of CMV therapy.     

CMV plasma DNAemia and risk of cancer among HIV-infected patients: A case–control study nested in the ANRS CO3 Aquitaine Cohort,France, 2002–2007

BackgroundCMV reactivation, which enhances immune senescence, could be associated with a higher risk of cancer.ObjectivesWe compared the prevalence of positive CMV DNAemia in HIV-infected patients with and without cancer.Study designThis case–control study, nested in the ANRS-CO3 Aquitaine Cohort, included patients with a first diagnosis of cancer (2002–2007) as cases. Two controls were matched per case.Cancer risk was estimated using conditional logistic regression models, an Odds Ratio (OR) of 2 could be detected with 80% power. The variables considered were: ≥1 positive CMV DNAemia, CD4+ and CD8+ counts, HIV plasma load. Plasma CMV DNA was retrospectively quantified within the 3-year period preceding the endpoint.ResultsThe 143 cases (93 non-AIDS-related and 50 AIDS-related cancers) and 284 controls had a median age of 47 years (IQR: 41–56). At the time of diagnosis or censorship, for cases and controls, median values were respectively, for CD4+ count: 327 cells/mm³ (IQR: 164–514) and 416 (IQR: 275–582), and for HIV plasma load: 2.6 log₁₀ copies/mL (IQR: 1.7–4.7) and 1.7 log₁₀ copies/mL (IQR: 1.7–3.3). We performed 2056 CMV PCR; 14 cases (9.8% [95% CI: 4.9–14.7]) and 19 controls (6.7% [CI: 3.8–9.6]) presented ≥1 positive PCR. CMV DNAemia was not associated with the risk of cancer (unadjusted and adjusted p-values = 0.19 and 0.54, respectively). HIV load >500 copies/mL was independently associated with a higher risk of cancer (OR = 2.02; p = 0.002; 95% CI: 1.29–3.17).ConclusionThis large case–control study did not show any differential exposure to positive CMV plasma DNAemia between cancer cases and controls.     

Fully Automated Quantification of Cytomegalovirus (CMV) in Whole Blood with the New Sensitive Abbott RealTime CMV Assay in the Era of the CMV International Standard

Fully standardized reproducible and sensitive quantification assays for cytomegalovirus (CMV) are needed to better define thresholds for antiviral therapy initiation and interruption. We evaluated the newly released Abbott RealTime CMV assay for CMV quantification in whole blood (WB) that includes automated extraction and amplification (m2000 RealTime system). Sensitivity, accuracy, linearity, and intra- and interassay variability were validated in a WB matrix using Quality Control for Molecular Diagnostics (QCMD) panels and the WHO international standard (IS). The intra- and interassay coefficients of variation were 1.37% and 2.09% at 5 log₁₀ copies/ml and 2.41% and 3.80% at 3 log₁₀ copies/ml, respectively. According to expected values for the QCMD and Abbott RealTime CMV methods, the lower limits of quantification were 104 and <50 copies/ml, respectively. The conversion factor between international units and copies (2.18), determined from serial dilutions of the WHO IS in WB, was significantly different from the factor provided by the manufacturer (1.56) (P = 0.001). Results from 302 clinical samples were compared with those from the Qiagen artus CMV assay on the same m2000 RealTime system. The two assays provided highly concordant results (concordance correlation coefficient, 0.92), but the Abbott RealTime CMV assay detected and quantified, respectively, 20.6% and 47.8% more samples than the Qiagen/artus CMV assay. The sensitivity and reproducibility of the results, along with the automation, fulfilled the quality requirements for implementation of the Abbott RealTime CMV assay in clinical settings. Our results highlight the need for careful validation of conversion factors provided by the manufacturers for the WHO IS in WB to allow future comparison of results obtained with different assays.     

BK polyomavirus-associated hemorrhagic cystitis among pediatric allogeneic bone marrow transplant recipients: Treatment response and evidence for nosocomial transmission

BackgroundBK polyomavirus-associated hemorrhagic cystitis (BK-PyVHC) is a significant complication of allogenic hematopoietic stem cell transplantation (HSCT), but risk factors and treatment are currently unresolved. BK-PyVHC typically presents with clinical cystitis, macrohematuria, and increasing urine and blood BKV loads.ObjectivesCharacterization of children undergoing allogeneic HSCT with BK-PyVHC and their clinical and antibody response to cidofovir treatment.Study designBy prospective screening of urine and plasma in 50 pediatric allogenic HSCT performed between 2008 and 2010, we identified 6 (12%) children with BK-PyVHC. Cidofovir was administered intravenously to 5 patients and intravesically to 4 patients (3 double treatments).ResultsDecreasing BKV viremia of > 2 log₁₀ copies/mL and clinical resolution was seen in 4 patients over 5–12 weeks. Responses occurred only in patients mounting BKV-specific IgM and IgG responses. Epidemic curve plots, BKV genotyping and contact tracing provided evidence of transmission between 2 BKV-seronegative patients, but ruled out transmission among the remaining four patientsConclusionsThe data suggest that BK-PyVHC may be the result of nosocomial transmission in children with low/undetectable BKV antibodies and raises urgent questions about appropriate infection control measures and the role of cidofovir.     

Evaluation of DNA extraction methods for dried blood spots in the diagnosis of congenital cytomegalovirus infection

BackgroundDried blood spots (DBS) may be valuable in the diagnosis of congenital cytomegalovirus (CMV) infection. However, the 2007 European Quality Control for Molecular Diagnostics (QCMD) proficiency testing programme showed that CMV DNA detection in DBS was lacking sensitivity in a considerable number of participating laboratories.ObjectiveTo compare DNA extraction methods for DBS for detecting CMV. Sensitivity and applicability of the methods for high-throughput usage were assessed.Study designGuthrie cards were spotted with CMV DNA-positive whole blood (n = 15). DNA was extracted from the DBS using different extraction methods, followed by CMV amplification by means of real-time PCR.ResultsSignificant differences between the extraction methods with respect to the sensitivity were found. Optimal sensitivity was achieved when samples were tested in triplicate, demonstrating that the methods in general operated around their detection limits. Triplicate testing using the protocol by Barbi et al. [Barbi M, et al. Cytomegalovirus DNA detection in Guthrie cards: a powerful tool for diagnosing congenital infection. J Clin Virol 2000;17:159–65], representing the most sensitive methods, resulted in sensitivities of 100%, 86%, and 50% for DBS with CMV DNA loads of 5–4, 4–3, and 3–2 log₁₀ copies/ml, respectively. This indicates that sensitivity limitations apply in the clinically relevant concentration range. Few methods appeared suitable for 96-well format high-throughput testing.DiscussionWhen considering universal neonatal screening for congenital CMV infection, an assay which is both sensitive and applicable for high-throughput testing is required. The protocol by Barbi et al. and the BioRobot Universal System appear appropriate candidates currently available for 96-well format application in neonatal screening using DBS.     

Toward Standardization of BK Virus Monitoring: Evaluation of the BK Virus R-gene Kit for Quantification of BK Viral Load in Urine,Whole-Blood,and Plasma Specimens

Screening of BK virus (BKV) replication is recommended to identify patients at increased risk of BKV-associated diseases. However, the heterogeneity of molecular techniques hinders the establishment of universal guidelines for BKV monitoring. Here we aimed to compare the performance of the CE-marked BK virus R-gene kit (R-gene) to the performance of our in-house assay for quantification of BKV DNA loads (BKVL). A 12-specimen panel from the Quality Control for Molecular Diagnostics (QCMD) organization, 163 urine samples, and 88 paired specimens of plasma and whole blood (WB) from transplant recipients were tested. Both the R-gene and in-house assays showed a good correlation within the QCMD panel (r = 0.995 and r = 0.989, respectively). BKVL were highly correlated between assays, although positive biases were observed with the in-house assay in analysis of urine (0.72 ± 0.83 log₁₀ copies/ml), plasma (1.17 ± 0.63 log₁₀ copies/ml), and WB (1.28 ± 0.37 log₁₀ copies/ml). Recalibration with a common calibrator significantly reduced the bias in comparisons between assays. In contrast, BKVL was underestimated with the in-house PCR in eight samples containing BKV genotype II, presenting point mutations at primer-annealing sites. Using the R-gene assay, plasma and WB specimens were found to be equally suitable for quantification of BKVL, as indicated by the high correlation coefficient (r = 0.965, P < 0.0001). In conclusion, the R-gene assay demonstrated reliable performance and higher accuracy than the in-house assay for quantification of BKVL in urine and blood specimens. Screening of BKV replication by a well-validated commercial kit may enable clinical laboratories to assess viral loads with greater reproducibility and precision.     

Comparative effectiveness of dried plasma HIV-1 viral load testing in Brazil using ViveST for sample collection

BackgroundUtilization of dried plasma for HIV-1 viral load testing would significantly decrease sample shipping costs.ObjectivesTo describe the precision and reproducibility of ViveST^® (ST) as a transportation method for shipping specimens for HIV-1 viral load (VL) testing.Study designThirty clinical plasma samples were used to generate replicate samples with HIV VL values of 4 log₁₀, 3 log₁₀ and 2 log₁₀ copies/mL for reproducibility testing and an additional 299 samples with HIV VL <50 copies/mL (99); 1.7 log₁₀ to 3.99 log₁₀ (100); and 4 log₁₀ to 5.99 log₁₀/mL (100) were used to compare ViveST to frozen plasma samples using the VERSANT^® HIV-1 RNA 3.0 Assay. Results were compared using Student t-test, Pearson correlation and Bland–Altman analyses.ResultsMean intra-assay variance among frozen and dried plasma triplicates was 0.15 log₁₀ and 0.09 log₁₀ copies/mL respectively (n = 10, P = NS). Compared to frozen plasma, there was a mean reduction of 0.3 log₁₀, 0.27 log₁₀, and 0.35 log₁₀ copies/mL at the 4 log₁₀, 3 log₁₀, and 2 log₁₀ copy/mL samples respectively (n = 30, all comparisons, P < 0.01). Overall correlation between 299 frozen and ViveST samples was r = 0.97, where 12 of 99 undetectable frozen VL were positive with ST, and 12 of 200 frozen detectable VL were undetectable with ViveST (mean VL 2.1, 1.9 log₁₀ copies/mL respectively).ConclusionsHIV-1 viral load results using ViveST were reproducible, correlated well with frozen plasma, though yielding minimally lower values. Our data suggest that dried plasma for HIV-1 VL testing using ViveST has promise for use in HIV clinical practice.     

Neurofilament ELISA validation

BackgroundNeurofilament proteins (Nf) are highly specific biomarkers for neuronal death and axonal degeneration. As these markers become more widely used, an inter-laboratory validation study is required to identify assay criteria for high quality performance.MethodsThe UmanDiagnostics NF-light ®enzyme-linked immunoabsorbent assays (ELISA) for the neurofilament light chain (NfL, 68 kDa) was used to test the intra-assay and inter-laboratory coefficient of variation (CV) between 35 laboratories worldwide on 15 cerebrospinal fluid (CSF) samples. Critical factors, such as sample transport and storage, analytical delays, reaction temperature and time, the laboratories' accuracy and preparation of standards were documented and used for the statistical analyses.ResultsThe intra-laboratory CV averaged 3.3% and the inter-laboratory CV 59%. The results from the test laboratories correlated with those from the reference laboratory (R = 0.60, p < 0.0001). Correcting for critical factors improved the strength of the correlation. Differences in the accuracy of standard preparation were identified as the most critical factor. Correcting for the error introduced by variation in the protein standards improved the correlation to R = 0.98, p < 0.0001 with an averaged inter-laboratory CV of 14%. The corrected overall inter-rater agreement was subtantial (0.6) according to Fleiss' multi-rater kappa and Gwet's AC1 statistics.ConclusionThis multi-center validation study identified the lack of preparation of accurate and consistent protein standards as the main reason for a poor inter-laboratory CV. This issue is also relevant to other protein biomarkers based on this type of assay and will need to be solved in order to achieve an acceptable level of analytical accuracy. The raw data of this study is available online.     

Analytical and clinical performance characteristics of the Simplexa BK virus quantitative PCR assay for the diagnosis of polyomavirus-associated nephropathy in renal transplant recipients using plasma and urine specimens

BackgroundPolyomavirus-associated nephropathy is a significant cause of kidney rejection in renal transplant recipients. Quantification of BK viral load in plasma and urine can predict the development of polyomavirus-associated nephropathy, though each assay requires careful evaluation of analytical and clinical performance characteristics for optimal use.ObjectivesThis study evaluated the analytical and clinical performance characteristics of the Simplexa BK virus quantitative PCR assay.Study designAnalytical validation was performed using commercial standards, BK virus stock culture, and patient specimens. Clinical performance was evaluated using biopsy-proven BK nephropathy as the gold standard.ResultsThe Simplexa BK virus quantitative PCR assay was linear over a range of 2.7–10.4 log₁₀ copies/mL. Limit of detection was 2.7–2.8 log₁₀ copies/mL in plasma and urine samples. Sensitivities were 100% and 100% and specificities were 84% and 86% for plasma and urine samples, respectively, when compared to a reference BK assay. Clinical cutoff values of 4.0 log₁₀ copies/mL (plasma) and 7.5 log₁₀ copies/mL (urine) yielded 100% sensitivity and specificities of 87.5% and 85%, respectively, for biopsy-proven polyomavirus nephropathy.ConclusionsThe Simplexa BK virus quantitative PCR assay has high sensitivity and acceptable analytical characteristics for clinical use. The clinical cutoff values presented here provide a rational approach to the monitoring and treatment of renal transplant recipients for polyomavirus-associated nephropathy.     

Clinical evaluation of a fully automated CMV PCR assay

BackgroundThere is a growing need for sensitive high-throughput cytomegalovirus (CMV) PCR tests due to the increasing number of immunocompromised patients requiring monitoring for active CMV infection.ObjectivesTo compare the fully automated COBAS^® AmpliPrep/COBAS^® TaqMan^® (CAP/CTM) CMV test (this test is currently under development and not commercially available) for EDTA–plasma to the reference method COBAS^® AMPLICOR CMV MONITOR.Study designA prospective feasibility study with parallel analysis of 433 EDTA–plasma samples from 277 patients on both systems was carried out after the analytical performance of the new system had been assessed.ResultsThe new system has a wide linear range from 2.0 to 7.3 log₁₀ CMV-DNA copies/ml EDTA–plasma and a detection limit of 46 copies/ml with excellent accuracy and precision. When testing clinical samples, the CAP/CTM CMV test compared extremely well with the COBAS^® AMPLICOR CMV MONITOR (R² = 0.93, p < 0.001) with increased sensitivity and linear range. Discrepant samples all contained low titers of CMV-DNA. In two of the study patients, CMV-DNAemia was detected by the CAP/CTM CMV test up to eight weeks earlier than by COBAS^® AMPLICOR CMV MONITOR.ConclusionAn IVD/CE marked version of the CAP/CTM CMV test will enable laboratories to provide a sensitive, fully automated high-throughput CMV PCR.     

Effect of artemether-lumefantrine (Coartem) on cytomegalovirus urine viral load during and following treatment for malaria in children

BackgroundArtemisinins, commonly used to treat malaria, have shown activity against cytomegalovirus (CMV) in vitro, in an animal model, and in case reports; however, the in vivo anti-CMV activity has not been well investigated.ObjectivesTo evaluate whether artemisinins affect CMV shedding among subjects co-infected with CMV and malaria.Study designA prospective observational study of children in Mali (6 month–10 year) presenting with fever. Urine samples were collected at day 0, 3, and 14 from children treated with artemether-lumefantrine (Coartem^®) for malaria and those who had other illnesses not treated with Coartem. CMV DNA was quantified using a real-time PCR. Resulting urine viral loads were compared between the groups at three time points.Results164 malaria cases and 143 non-malaria comparisons were enrolled. Eighty-one (49%) cases and 88 (62%) comparisons shed CMV at day 0. Day 0 and day 3 viral loads were similar, but at day 14 the median viral load of cases was lower than that of comparisons (360 vs 720 copies/mL or 2.56 vs 2.86 log₁₀), p = 0.059. A stratified analysis of day 0 high viral shedders (defined as >1000 copies/mL) showed significantly lower median viral load at day 14 among cases (490 copies/mL, 2.69 log₁₀) vs comparisons (1200 copies/mL, 3.08 log₁₀), p = 0.045.ConclusionA high rate of urinary CMV shedding was found in a malaria-endemic area. Among high virus shedders artemether-lumefantrine decreased urine viral load, but the effect was not observed when analysis of both high and low shedders was performed. These results support additional studies of artemisinin dosing and duration in CMV infection.     

Performance of a completely automated system for monitoring CMV DNA in plasma

BackgroundCompletely automated systems for monitoring CMV-DNA in plasma samples are now available.ObjectivesEvaluate analytical and clinical performances of the VERIS™/MDx System CMV Assay^®.Study designAnalytical performance was assessed using quantified quality controls. Clinical performance was assessed by comparison with the COBAS^® Ampliprep™/COBAS^® Taqman CMV test using 169 plasma samples that had tested positive with the in-house technique in whole blood.ResultsThe specificity of the VERIS™/MDx System CMV Assay^® was 99% [CI 95%: 97.7–100]. Intra-assay reproducibilities were 0.03, 0.04, 0.05 and 0.04 log₁₀ IU/ml (means 2.78, 3.70, 4.64 and 5.60 log₁₀ IU/ml) for expected values of 2.70, 3.70, 4.70 and 5.70 log₁₀ IU/ml. The inter-assay reproducibilities were 0.12 and 0.08 (means 6.30 and 2.85 log₁₀ IU/ml) for expected values of 6.28 and 2.80 log₁₀ IU/ml. The lower limit of detection was 14.6 IU/ml, and the assay was linear from 2.34 to 5.58 log₁₀ IU/ml. The results for the positive samples were concordant (r = 0.71, p < 0.0001; slope of Deming regression 0.79 [CI 95%: 0.56–1.57] and y-intercept 0.79 [CI 95%: 0.63–0.95]). The VERIS™/MDx System CMV Assay^® detected 18 more positive samples than did the COBAS^® Ampliprep™/COBAS^® Taqman CMV test and the mean virus load were higher (0.41 log₁₀ IU/ml). Patient monitoring on 68 samples collected from 17 immunosuppressed patients showed similar trends between the two assays. As secondary question, virus loads detected by the VERIS™/MDx System CMV Assay^® were compared to those of the in-house procedure on whole blood. The results were similar between the two assays (−0.09 log₁₀ IU/ml) as were the patient monitoring trends.ConclusionThe performances of the VERIS™/MDx System CMV Assay^® facilitated its routine use in monitoring CMV-DNA loads in plasma samples.     

Comparative performance of the new Aptima HIV-1 Quant Dx assay with three commercial PCR-based HIV-1 RNA quantitation assays

BackgroundQuantitative measurement of HIV-1 RNA levels in plasma (‘viral load’) plays a central role in clinical management. The choice of assay platform can influence results and treatment decisions.ObjectiveTo compare the analytical performance of the new TMA-based Hologic Aptima^® HIV-1 Quant Dx assay with that of three PCR-based assays: Abbott RealTime HIV-1, Qiagen Artus^® HI Virus-1 QS-RGQ, and Roche CAP/CTM HIV-1 Test v2.Study designAssay performance was evaluated using Acrometrix HIV-1 RNA Standard panels; the 3rd WHO HIV-1 RNA International Standard (12–500 copies/ml; 6 dilutions; 9 replicates); and plasma samples from 191 HIV-positive patients.ResultsAptima showed high (>0.99) precision, accuracy and concordance with the Acrometrix Standards across a wide dynamic range (2.0–6.7 log₁₀ copies/ml). Variance caused up to 2.1 (Aptima), 1.7 (RealTime), 7.5 (Artus), and 1.9 (CAP/CTM) fold changes in the International Standard quantifications at 50–500 copies/ml. HIV-1 RNA detection rates in plasma samples were 141/191 (74%), 119/191 (62%), 108/191 (57%), and 145/191 (76%) for Aptima, RealTime, Artus and CAP/CTM, respectively. For categorising samples either side of 50 copies/ml, Aptima had excellent agreement with RealTime (kappa 0.92; 95% CI 0.87–0.98); lowest agreement was with Artus (kappa 0.79; 95%CI 0.70–0.88). Aptima quantifications were mean 0.12 and 0.06 log₁₀ copies/ml higher compared with RealTime and CAP/CTM, respectively, and 0.05 log₁₀ copies/ml lower compared with Artus. Limits of agreement were narrowest when comparing Aptima to RealTime.ConclusionsThe new Aptima HIV assay is sensitive, precise, and accurate. HIV assays exhibit discordance at low HIV-1 RNA copy numbers.     

Performance evaluation of the point-of-care INSTI™ HIV-1/2 antibody test in early and established HIV infections

BackgroundThe flow-through INSTI™ HIV-1/HIV-2 Rapid Antibody (INSTI) test is a 60 s FDA-approved test for HIV-1 and HIV-2 antibody testing using whole blood and plasma.ObjectiveWe evaluated the performance of INSTI using plasma and simulated whole blood specimens.Study designINSTI’s performance in plasma specimens from commercial seroconversion panels was assessed by estimating the relative sensitivity using a 50% cumulative frequency analysis and by comparing its performance with other FDA-approved rapid tests (RTs). INSTI was further evaluated using 320 HIV-1 plasma specimens collected during a cross-sectional study and with 107 HIV-1 and 24 HIV-2 simulated whole blood specimens. Sensitivity and specificity were calculated using 615 known HIV-1 group M/O and 80 HIV-2 (Western blot (WB)-positive), and 497 HIV-negative plasma specimens, respectively.ResultsIn HIV-1 seroconversion panels, INSTI became reactive 9 days before a positive WB. When compared to FDA-approved antibody-based lateral flow RTs, INSTI detected significantly more early infections. Among HIV-1-infected cross-sectional plasma samples, INSTI detected 23 (27%) of 85 Architect-positive/Multispot-negative or indeterminate specimens. For plasma specimens, the sensitivity was 99.84% for HIV-1 and 100% for HIV-2, and the specificity was 99.80%. Using simulated whole blood from seroconverters, INSTI performed similarly to plasma.ConclusionsINSTI performed significantly better than antibody-based lateral flow RTs during early stages of seroconversion. Sensitivity and specificity were within the manufacturer’s reported ranges. Considering the observed test performance and the almost immediate results, INSTI is an accurate option to detect HIV-1/HIV-2 antibodies in point-of-care settings where lab testing is not feasible.     

Acute viral hepatitis – Should the current screening strategy be modified?

BackgroundThe epidemiology of viral hepatitis has changed. Since the introduction of safe and effective vaccines for hepatitis A and B in 1980s, the incidence of acute infections caused by these viruses has been declining in the UK. At the same time, hepatitis E virus (HEV) has been recognised as an increasingly important cause of acute hepatitis, but testing is not widely available.ObjectivesThe aim of this study was to establish the viral causes of acute hepatitis, and use that data to modify the current diagnostic algorithm.Study designA Cognos search was performed to collate subjects tested for HAV, HBV, HCV, HEV, EBV and CMV between June 2010 and December 2012. Information included virological result and their ALT level if done within 5 days from virological testing.ResultsFrom 3462 subjects with suspected acute viral hepatitis, only 25% had biochemical evidence of acute hepatitis (n = 854; ALT > 100 IU/l). The frequency of detection of acute HEV infection (25/409) was over 31-times higher than that of HAV (6/3462), and 7-times higher than that of HBV (24/3462). Most cases of acute HAV, HEV, EBV and CMV infections presented with abnormal ALT levels. Most EBV infections were associated with lymphadenopathy (23/34); in comparison most of CMV infections were not associated with lymphadenopathy (18/22).ConclusionsHEV screening should be included in the initial testing panel for acute hepatitis and screening at least for HAV and HEV might be limited to those with abnormal ALT levels.     

Epstein-Barr virus DNA load kinetics analysis in allogeneic hematopoietic stem cell transplant recipients: Is it of any clinical usefulness?

BackgroundThere is a lack of clinical information regarding the usefulness of plasma Epstein-Barr virus (EBV) DNA load kinetics analyses in the management of EBV infections in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Namely, it remains unknown whether this type of analysis can help physicians to anticipate the development of high-level EBV DNAemia episodes requiring rituximab treatment or predict the risk of recurrent EBV DNAemia or post-transplant lymphoproliferative disorders (PTLDs).Study designUnicentric, retrospective, observational study including 142 consecutive patients undergoing T-cell replete allo-HSCT. The plasma EBV DNA load was monitored on a weekly basis using the artus^® EBV PCR kit.ResultsFifty-five of the 142 patients (38.7%) developed at least one episode of EBV DNAemia; 13 of the 55 initial EBV DNAemia episodes (23.6%) were preemptively treated with rituximab, 7 patients had a recurrent episode of EBV DNAemia, and biopsy-proven PTLDs were diagnosed in 4 patients. The initial plasma EBV DNA load was not significantly different (P = 0.269) in episodes of self-resolving EBV DNAemia, those requiring rituximab treatment, or those leading to PTLDs. The plasma EBV DNA load doubling times were similar across all the groups (P = 0.799), and the EBV DNA-load half-life was not associated with the occurrence of recurrent EBV DNAemia (P = 0.550).ConclusionPlasma EBV DNA-load kinetics analyses are unlikely to be useful in predicting the occurrence of high-level EBV DNAemia, PTLD, or recurrent EBV DNAemia.     

Impact of stem cell graft on early viral infections and immune reconstitution after allogeneic transplantation in adults

BackgroundViral infections are well-known complications after allogeneic stem cell transplant (allo-SCT).ObjectivesWe compared prospectively incidences of DNAemia and active infections (AI) for five opportunistic viruses (Human Herpesvirus 6 (HHV-6), Epstein-Barr virus (EBV), BK polyomavirus (BKPyV), Cytomegalovirus (CMV) and Adenovirus (ADV)) and kinetics of immune reconstitution (IR) in adults receiving either double umbilical cord blood (dUCB group) or unrelated peripheral blood stem cell (uPBSC group) allo-SCT after a reduced-intensity conditioning (RIC) regimen.Study designWhole blood samples were collected at transplant, every 15 days during the first 3 months and at 4, 5 and 6 months post-transplant.ResultsSixty-five patients were enrolled (uPBSC n = 34; dUCB n = 31). Incidences of HHV-6 and BKPyV DNAemia were significantly higher for dUCB (97% vs 23.5% and 58% vs 32%, respectively) while EBV DNAemia was more frequently detected in uPBSC (71% vs 26%). The incidence of CMV DNAemia was similar between both groups. ADV AI developed only in dUCB. HHV-6 AI were also higher in dUCB (84% vs 21%). In multivariate analysis, dUCB graft was the only independent factor associated with HHV-6 DNAemia (OR: 19.0; 95%CI: 5.2–69.1; p < 0.0001) while EBV DNAemia were significantly associated with uPBSC (OR: 29.9; 95%CI: 5.68–158; p < 0.0001). dUCB graft was also the only factor associated with HHV-6 AI. Finally, higher counts and faster recoveries of B lymphocytes (p<0.0001) and monocytes (p = 0.0007) were observed in the dUCB group.ConclusionWe demonstrate a strong correlation between sources of graft and patterns of viral DNAemia and AI and IR after RIC allo-SCT.     

Correlation between HIV-1 viral load quantification in plasma,dried blood spots,and dried plasma spots using the Roche COBAS Taqman assay

BackgroundThe use of simplified methods for viral load determination could greatly increase access to treatment monitoring of HIV patients in resource-limited countries.ObjectiveThe aim of the present study was to optimize and evaluate the performance of the Roche COBAS Taqman assay in HIV-RNA quantification from dried blood spots (DBS) and dried plasma spots (DPS).Study designEDTA blood samples from 108 HIV-infected women were used to prepare 129 DBS and 76 DPS on Whatman 903 card. DBS and DPS were stored at ?20 °C. HIV-1 RNA was extracted from DBS/DPS using the MiniMAG system (bioMerieux). Amplification and detection were performed using the Roche COBAS TaqMan assay. Plasma viral load results were used as standard.ResultsThere was a high correlation between measures of viral load in plasma and in DBS/DPS (r = 0.96 and 0.85 respectively, P < 0.001). Overall, viral load values in DBS and DPS tended to be lower than in plasma with mean (SD) differences of 0.32 log (0.22) for DBS and of 0.35 (0.33) for DPS. Detection rates were 96.4% for DBS and 96.1% for DPS in samples with corresponding plasma values >3.0 log copies/ml. Samples with HIV-RNA below 50 copies/ml were correctly identified in 18/19 DBS and in 7/7 DPS.ConclusionsBoth DBS and DPS provided results highly correlated to the plasma values. High detection rate was obtained with both DBS and DPS when HIV-RNA was >3.0 log copies/ml. Our results support the use of DBS/DPS to detect virologic failure in resource-limited settings.