Coexistence of circulating HBsAg and anti-HBs antibodies in chronic hepatitis B carriers is not a simple analytical artifact and does not influence HBsAg quantification

BackgroundPresence at the same time of HBsAg and anti-HBs antibodies (HBsAg/Ab) is an entity sometimes encountered in chronic hepatitis B (CHB) carriers.ObjectivesThis study was designed to characterize such serological profiles and to assess the reliability of serological marker quantification by three commercially available assays in this setting.Study designAmong 2578 CHB identified patients, 129 (5%) had an HBsAg/Ab profile as determined by Abbott Architect. After exclusion of co-infections (HIV, HCV, HDV), HBV reactivation or HBIg treatment, 101 samples from 62 patients were tested for HBsAg and anti-HBs quantification using Architect, DiaSorin Liaison-XL and Roche Modular-Cobas. Influence of genotype and HBsAg variants was studied in 31 samples with HBV replication.ResultsHBsAg detection was confirmed with the 3 techniques for 98% (n = 99) of the samples while the HBsAg/Ab profile was concordant between all techniques for 65% of them. The overall correlation between the 3 HBsAg quantification techniques was good (R²: 0.94–0.97). The median HBsAg concentration was comparable for the 99 samples whatever the used technique but a bias of −0.11 and 0.02 log IU/mL were noticed for DiaSorin and Roche compared to Abbott, respectively. Anti-HBs quantifications were poorly correlated between techniques with major discrepancies observed. Genotype and substitutions within the “a” determinant showed an impact on HBsAg quantification.ConclusionsThe double HBsAg/Ab profile is not an analytical artifact and is confirmed on all commercially available techniques. While such profile does not influence HBsAg quantification, differences of HBsAg quantification were noticed according to HBV genotype or HBsAg variant.     

Relevance of cutoff on a 4th generation ELISA performance in the false positive rate during HIV diagnostic in a low HIV prevalence setting

BackgroundDespite the high specificity of fourth-generation enzyme immunoassays (4th-gen-EIA) for screening during HIV diagnosis, their positive predictive value is low in populations with low HIV prevalence. Thus, screening should be optimized to reduce false positive results.ObjectivesThe influence of sample cutoff (S/CO) values by a 4th-gen-EIA with the false positive rate during the routine HIV diagnosis in a low HIV prevalence population was evaluated.Study designA total of 30,201 sera were tested for HIV diagnosis using Abbott Architect^® HIV-Ag/Ab-Combo 4th-gen-EIA at a hospital in Spain during 17 months. Architect S/CO values were recorded, comparing the HIV-1 positive results following Architect interpretation (S/CO ≥ 1) with the final HIV-1 diagnosis by confirmatory tests (line immunoassay, LIA and/or nucleic acid test, NAT). ROC curve was also performed.ResultsAmong the 30,201 HIV performed tests, 256 (0.85%) were positive according to Architect interpretation (S/CO ≥ 1) but only 229 (0.76%) were definitively HIV-1 positive after LIA and/or NAT. Thus, 27 (10.5%) of 256 samples with S/CO ≥ 1 by Architect were false positive diagnose. The false positive rate decreased when the S/CO ratio increased. All 19 samples with S/CO ≤10 were false positives and all 220 with S/CO > 50 true HIV-positives. The optimal S/CO cutoff value provided by ROC curves was 32.7. No false negative results were found.ConclusionsWe show that very low S/CO values during HIV-1 screening using Architect can result HIV negative after confirmation by LIA and NAT. The false positive rate is reduced when S/CO increases.     

Performance of the DiaSorin LIAISON anti-HBs II for the detection of hepatitis B surface antibodies: Comparison with the Abbott Architect anti-HBs assay

BackgroundDetection of hepatitis B virus (HBV) surface antibodies (anti-HBs) is required in order to evaluate the response to hepatitis B vaccination and to optimize post-exposure monitoring. The widespread use of vaccines has highlighted the need for accurate and consistent quantification, yielding comparable quantitative results.ObjectivesThis study assessed the adequacy of DiaSorin LIAISON^® anti-HBs II assay in detecting anti-HBs antibodies and determined the correlation with Abbott Architect anti-HBs quantification.Study designAnti-HBs levels were measured in parallel using Abbott and DiaSorin kits on WHO international standard dilutions and 350 routine samples pre-screened with Abbott Architect anti-HBs. Three different serological panels were tested: vaccinated subjects (n = 121); subjects with past HBV infection (n = 109); and subjects with no HBV infection marker (n = 69). Serial dilutions from nine high-titer anti-HBs samples were used to address linearity.ResultsAnti-HBs concentration measured on WHO standard dilutions indicated a good calibration of DiaSorin values against international units, while results for Abbott were below those expected. A strong impact of the dilution matrix used was observed when performing dilutions on high-titer samples. Despite difference in absolute quantification, the overall clinical agreement between the two assays was 96.9%, with strong correlation (r = 0.92) between concentrations and good linearity over the quantification range.ConclusionsThe DiaSorin LIAISON^® anti-HBs II assay shows excellent standardization to the WHO standard and good linearity. The assay is suitable for current clinical laboratory practice.     

Performance of HBsAg quantification assays for detection of Hepatitis B virus genotypes and diagnostic escape-variants in clinical samples

BackgroundThe impact of hepatitis B virus (HBV) genomic variability on the measurement of HBsAg level has been poorly evaluated.ObjectiveThis study was designed to compare the performance of all the available assays measuring HBsAg level in this setting.Study designA large selection of wild type HBV genotypes (n = 184) and HBsAg strains harboring mutations in the S gene (n = 81) from clinical samples was studied with three HBsAg quantification assays: Architect HBsAg (Abbott), LiaisonXL Murex HBsAg Quant (DiaSorin) and the Elecsys HBsAgII (Roche).ResultsThe overall percentage of positive results was 99.2% for Abbott, 98.9% for DiaSorin and 98.1% for Roche. Abbott and Roche assays provided an excellent concordance in HBsAg quantification (global mean bias of −0.006 logIU/mL). By contrast, DiaSorin underestimated HBsAg level with values 0.112 logIU/ml and 0.103 logIU/ml lower than Abbott and Roche, respectively. By contrast, DiaSorin slightly over quantified gtC (2.5% over the expected value) while Abbott provided values 6.2% lower than expected and 16.2% lower than what observed for the other genotypes. HBsAg quantitative assays were influenced by HBs protein substitutions irrespective to the genotype but no specific protein pattern that would particularly impair the quantification by one technique has been identified. However, Roche seemed to be particularly impacted by substitutions at 145 residue: 75% of under quantified samples carried a substituted 145 residue.ConclusionThis head-to-head comparison indicates a good correlation between all current systems used to quantify HBsAg but clearly shows an influence of both the genotype and the presence of “a” determinant variants in the absolute quantification of HBsAg. While these discrepancies may not translate into major clinical consequence, they may explain an absence of detection of weak concentration of HBsAg on some systems.     

Clinical implications of hepatitis B surface antigen quantitation in the natural history of chronic hepatitis B virus infection

BackgroundHBsAg quantitation may be useful for managing patients with hepatitis B virus (HBV) infection.ObjectivesWe explored the clinical implications of HBsAg quantitation for patients with HBsAg levels >250 IU/ml (Abbott Diagnostics).Study designTwo hundred and thirty-three HBV-infected patients comprising 29 immune tolerance cases, 49 treatment-naïve HBeAg-positive chronic hepatitis B (CHB) cases, 91 inactive HBV carrier cases, and 64 treatment-naïve HBeAg-negative CHB cases were analyzed. HBsAg was quantified by the Architect HBsAg assay (Abbott Diagnostics) after a 1:500 automated dilution.Results and conclusionsHBsAg (log 10 IU/ml) was established for immune tolerance (4.50 ± 0.43), HBeAg-positive CHB (4.17 ± 0.66), inactive HBV carrier (3.32 ± 0.44), and HBeAg-negative CHB (3.23 ± 0.40); (p = 4.92 × 10⁻³⁵). No significant difference was observed between inactive HBV carrier and HBeAg-negative CHB (p = 0.247). The proportions of HBsAg <2000 IU/ml for inactive HBV carrier and HBeAg-negative CHB were 51.6% and 59.3%, respectively (p = 0.341). Positive correlations between HBsAg and HBV DNA were observed for immune tolerance (p = 1.23 × 10⁻⁴) and HBeAg-positive CHB (p = 0.003), but not for HBeAg-negative CHB (p = 0.432). A negative correlation between HBsAg and age was observed for immune tolerance (p = 0.030), HBeAg-positive CHB (p = 0.016), and inactive HBV carrier (p = 0.001), but not in HBeAg-negative CHB (p = 0.249). No significant differences between HBsAg and ALT for HBeAg-positive (p = 0.338) or HBeAg-negative CHB (p = 0.564) were observed. For patients with HBsAg quantitation >250 IU/ml, HBsAg may reflect HBV DNA replication for HBeAg-positive cases. HBsAg is not a suitable marker for evaluating hepatitis activity and distinguishing between cases of HBeAg-negative CHB and inactive HBV carrier state.     

Performance comparison of the 4th generation Bio-Rad Laboratories GS HIV Combo Ag/Ab EIA on the EVOLIS™ automated system versus Abbott ARCHITECT HIV Ag/Ab Combo,Ortho Anti-HIV 1 + 2 EIA on Vitros ECi and Siemens HIV-1/O/2 enhanced on Advia Centaur

BackgroundA multisite study was conducted to evaluate the performance of the Bio-Rad 4th generation GS HIV Combo Ag/Ab EIA versus Abbott 4th generation ARCHITECT HIV Ag/Ab Combo. The performance of two 3rd generation EIAs, Ortho Diagnostics Anti-HIV 1 + 2 EIA and Siemens HIV 1/O/2 was also evaluated.ObjectiveStudy objective was comparison of analytical HIV-1 p24 antigen detection, sensitivity in HIV-1 seroconversion panels, specificity in blood donors and two HIV false reactive panels.Study designAnalytical sensitivity was evaluated with International HIV-1 p24 antigen standards, the AFFSAPS (pg/mL) and WHO 90/636 (IU/mL) standards; sensitivity in acute infection was compared on 55 seroconversion samples, and specificity was evaluated on 1000 negative blood donors and two false reactive panels.ResultsGS HIV Combo Ag/Ab demonstrated better analytical HIV antigen sensitivity compared to ARCHITECT HIV Ag/Ab Combo: 0.41 IU/mL versus 1.2 IU/mL (WHO) and 12.7 pg/mL versus 20.1 pg/mL (AFSSAPS); GS HIV Combo Ag/Ab EIA also demonstrated slightly better specificity compared to ARCHITECT HIV Ag/Ab Combo (100% versus 99.7%). The 4th generation HIV Combo tests detected seroconversion 7–11 days earlier than the 3rd generation HIV antibody only EIAs.ConclusionBoth 4th generation immunoassays demonstrated excellent performance in sensitivity, with the reduction of the serological window period (7–11 days earlier detection than the 3rd generation HIV tests). However, GS HIV Combo Ag/Ab demonstrated improved HIV antigen analytical sensitivity and slightly better specificity when compared to ARCHITECT HIV Ag/Ab Combo assay, with higher positive predictive values (PPV) for low prevalence populations.     

Comparative evaluation of three FDA-approved HIV Ag/Ab combination tests using a genetically diverse HIV panel and diagnostic specimens

BackgroundHIV Ag/Ab combination assays are recommended by CDC for routine screening and several HIV Ag/Ab combination tests are now FDA-approved. Maintaining high specificity and consistent sensitivity across diverse HIV strains is critical for these assays to accurately detect HIV infection and expedite delivery of patient results.ObjectivesTo evaluate performance of three FDA-approved HIV tests: ARCHITECT HIV Combo (Abbott), ADVIA Centaur HIV Combo (Siemens) and BioPlex HIV Ag-Ab (Bio-Rad).Study designSensitivity and specificity were evaluated using an extensive panel of 28 HIV infected human specimens and 17 cultured virus isolates representing multiple genotypes, 6 seroconversion panels, 4 human samples with acute infection, WHO p24 standard and 4020 clinical specimens.ResultsThe p24 limit of detection (LOD) for the WHO standard was 0.19 IU/ml, 0.70 IU/ml, and 1.77 IU/ml in BioPlex, ARCHITECT, and Centaur respectively. The distribution of LODs across 15 HIV-1 isolates was substantially narrower in ARCHITECT (5–33 pg/ml) than in BioPlex (11–198 pg/ml) and Centaur (6–384 pg/ml). All assays detected antibodies to the majority of HIV-1 and HIV-2 variants. However, reduced sensitivity was observed for Centaur in detection of antibodies to HIV-1 group M (CRF02_AG), O and N variants. BioPlex and ARCHITECT showed better seroconversion sensitivity than Centaur, detecting one bleed (3–7 days) earlier in 4 (BioPlex) and 3 (ARCHITECT) of 6 seroconversion panels. ARCHITECT demonstrated the highest specificity (99.90–100%) compared to BioPlex (99.80%) and Centaur (99.42%).ConclusionsThe overall performance of ARCHITECT and BioPlex was superior to Centaur, especially for detection of acute HIV infection.     

Evaluation of polyethylene glycol precipitation as screening test for macroprolactinemia using Architect immunoanalyser

We performed the polyethylene glycol (PEG) precipitation test to determine the prevalence of macroprolactinemia in 172 hyperprolactinemic subjects with prolactin (PRL) levels > 700 mIU/l. PRL was measured by Architect i2000 (Abbott Diagnostics) both in serum and in supernatant obtained after PEG. We used the PRL recovery percentage (R%) as interpretative criterion of PEG test and we estimated a prevalence of macroprolactinemia of 21.5% (R% ≤ 40%), whereas 74.4% of subjects showed a true hyperprolactinemia (R% ≥ 60%). In true hyperprolactinemic subjects PRL levels obtained before and after PEG showed a good correlation (Pearson coefficient, R = 0.995); in macroprolactinemic individuals no correlation was found. The PEG test was also performed in 50 normoprolactinemic subjects and a new PRL reference interval was obtained: 64–453 mIU/l. In this case the macroprolactinemic subjects (hyperprolactinemic presenting a normal PRL value after PEG) were 20.3% whereas 79.7% showed still elevated PRL levels. In 35 females we were also able to evaluate the symptoms and the pituitary imaging findings: no significant differences between macroprolactinemic (N = 11) and true hyperprolactinemic (N = 24) subjects were found. In conclusion, the PEG test appears to be simple, reproducible and absolutely necessary for diagnostics of hyperprolactinemia.     

Analytical performance of the VERIS MDx system HCV assay for detecting and quantifying HCV RNA

BackgroundThe diagnosis of HCV relies on the detection of viral RNA.ObjectiveTo evaluate the performance of the VERIS/MDx System HCV Assay, a new automated system for quantifying HCV RNA, and to compare with the COBAS^® Ampliprep/COBAS^® Taqman™ (CAPCTM) HCV Test version 2.0.Study designThe limit of detection was determined by Probit analysis with the 3rd International WHO HCV standard and precision by assaying in duplicate control samples with HCV RNA concentrations of 7.9; 5.0; 3.4; 1.6 and 0 log IU/ml over 20 days. Analytical specificity was assessed by assaying 180 samples from negative anti-HCV and HCV RNA blood donors and linearity with replicates of serial dilutions of a clinical plasma (6.4–0.6 log IU/ml). We compared the VERIS MDx HCV and CAPCTM HCV assays by testing 209 samples.ResultsThe limit of detection was 6.1 IU/ml [CI 95%: 5.0–8.3] and the precision, given by the standard deviation, was ≤0.11 log IU/ml. Specificity was 100%. The linearity ranged from 1.5 to 6.4 log IU/ml. Passing-Bablok regression analysis gave: VERIS log IU/ml = −0.33 + [1.04× CAPCTM] log IU/ml, with biases for the 25th, 50th, 75th percentiles of 0.18, −0.10 and −0.06 log IU/ml. The two assays were well correlated (ρ = 0.92, p < 0.001) and Bland-Altman analysis gave biases of 0.12, log IU/ml for genotype 1, −0.19 for genotype 2, −0.26 for genotype 3, and −0.77 for genotype 4.ConclusionThe VERIS MDx HCV assay performed well. But, we observed an under-quantification of the genotype 4 samples.     

Performance of a new rapid test for the detection of hepatitis B surface antigen in various patient populations

BackgroundRapid diagnostic tests (RDT) have been developed for the detection of hepatitis B surface antigen (HBsAg). They represent a promising alternative to enzyme immunoassays and a powerful tool for large-scale screening and diagnosis of HBV infection, especially in regions without easy access to serological and molecular testing.ObjectivesThe aims of the present study were to evaluate the characteristics and clinical performance of a new CE-marked HBsAg RDT, DRW-HBsAg v2.0 assay (Diagnostics for the Real World™, Ltd., USA), in various patient populations, including those chronically infected with HBV, patients with severe acute hepatitis of unknown origin and pregnant women with unknown HBV serological status at delivery.ResultsThe lower limit of detection of the assay, evaluated in 21 clinical samples, ranged from 0.30 ± 0.07 to 0.97 ± 0.26 international units/mL (using Abbott Architect as a reference), depending on the HBV genotype. The assay tested positive in 100% of patients with chronic hepatitis B, 96.3% of HBsAg-positive acute hepatitis patients, and 95.2% of HBsAg-positive pregnant women. Its specificity was 98.8% in HBsAg-negative patients, 98.7% in HBsAg-negative patients with acute hepatitis of unknown origin and 97.8% in HBsAg-negative pregnant women. Amino acid substitutions in the HBsAg major hydrophilic region did not affect HBsAg detection by DRW-HBsAg v2.0.ConclusionsThe new DRW-HBsAg v2.0 assay is a simple, rapid, easy-to-run and highly sensitive assay that can be used in both high- and low-risk populations for the diagnosis of HBsAg carriage. It appears to be a promising new tool for large-scale screening and diagnosis of HBV infection.     

Evaluation of the COBAS® AmpliPrep/COBAS® TaqMan® HCV Test,v2.0 and comparison to assays used in routine clinical practice in an international multicenter clinical trial: The ExPECT study

BackgroundThe COBAS^® AmpliPrep^®/COBAS^® TaqMan^® HCV Test, v2.0 (CAP/CTM2) is used for HCV RNA viral load monitoring.ObjectivesThe performance of the CAP/CTM2 was compared to other widely used tests, including a manual version of the assay (the COBAS^® TaqMan^® HCV Test, v2.0 for use with the High Pure System, HPS/CTM2) predominantly used during phase III clinical trials for the new direct acting antiviral therapies.Study designLow HCV RNA level comparisons were performed across tests (Abbott Realtime HCV Test, ART; COBAS^® AmpliPrep^®/COBAS^® TaqMan^® HCV Test, v1.0, CAP/CTM1; CAP/CTM2; and HPS/CTM2) using dilutions of the 2nd HCV WHO International Standard. Additionally, the clinical performance of the CAP/CTM2 was evaluated with 421 leftover HCV RNA-positive routine clinical samples.ResultsAll quantifiable WHO dilutions were within ±0.3 log₁₀ IU/mL of the expected results across tests and the analytical sensitivity resulted in a limit of detection of 12 IU/mL (95% confidence interval, 10, 15). When clinical samples were tested the results for 87% (367 of 421) of all sample comparisons were within ±0.5 log₁₀ IU/mL. When low viral load results (25–3500 IU/mL) were compared, values obtained by the ART assay were significantly lower (p < 0.0001) than those obtained with the CAP/CTM2.ConclusionsThe new CAP/CTM2 showed good accuracy with comparable sensitivity to comparator assays. The new kit is well-suited for use in the routine diagnostic laboratory, especially for accurate monitoring of patients receiving triple therapy or interferone-free regimens.     

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.     

Considerable decrease in antibodies against hepatitis B surface antigen following kidney transplantation

BackgroundImmunization against hepatitis B virus (HBV) in kidney transplantation (KT) candidates and recipients is recommended. If anti-HBV surface antigen antibody (anti-HBsAb) titer of 10 IU/L is admitted to be protective, the optimal threshold, at and after KT, is unknown. In addition, the natural evolution of anti-HBsAb titers after KT is not reported.ObjectivesTo describe rates of protective immunity to HBV at time of KT (baseline) and evolution of anti-HBsAb titers during the following year.Study designWe retrospectively analyzed HBV serology at baseline, 15 days, and 4 and 12 months post-KT. No patient received vaccination during the study period, but information about previous vaccination was unavailable.ResultsAt baseline 80% of 141 recipients had anti-HBsAb titer ≥10 IU/L. Among these 113 patients, 84 had subsequent HBV serologies at day 15 and month 4, and 67 had also serology at month 12. At month 12, 25% of patients had lost protective anti-HBsAb titers (p < 0.001). The duration of protective anti-HBsAb titers was significantly longer when the initial titer was ≥ 100 IU/L versus <100 IU/L (log-rank test p < 0.0001). Protective titers at month 12 persisted in 93% of patients with initial titer ≥100 IU/L compared to 33% with 10–100 IU/L titer (p < 0.0001). In contrast, duration of protective titers did not differ according to the anti-HBV core antigen antibody status at baseline.ConclusionsDespite a high prevalence of protective anti-HBsAb titer at KT, the loss of protective immunity during the following year was considerable, particularly when initial anti-HBsAb titer was <100 IU/L.     

Hepatitis B viral load in dried blood spots: A validation study in Zambia

BackgroundAccess to hepatitis B viral load (VL) testing is poor in sub-Saharan Africa (SSA) due to economic and logistical reasons.ObjectivesTo demonstrate the feasibility of testing dried blood spots (DBS) for hepatitis B virus (HBV) VL in a laboratory in Lusaka, Zambia, and to compare HBV VLs between DBS and plasma samples.Study designPaired plasma and DBS samples from HIV-HBV co-infected Zambian adults were analyzed for HBV VL using the COBAS AmpliPrep/COBAS TaqMan HBV test (Version 2.0) and for HBV genotype by direct sequencing. We used Bland-Altman analysis to compare VLs between sample types and by genotype. Logistic regression analysis was conducted to assess the probability of an undetectable DBS result by plasma VL.ResultsAmong 68 participants, median age was 34 years, 61.8% were men, and median plasma HBV VL was 3.98 log IU/ml (interquartile range, 2.04–5.95). Among sequenced viruses, 28 were genotype A1 and 27 were genotype E. Bland–Altman plots suggested strong agreement between DBS and plasma VLs. DBS VLs were on average 1.59 log IU/ml lower than plasma with 95% limits of agreement of −2.40 to −0.83 log IU/ml. At a plasma VL ≥2,000 IU/ml, the probability of an undetectable DBS result was 1.8% (95% CI: 0.5–6.6). At plasma VL ≥20,000 IU/ml this probability reduced to 0.2% (95% CI: 0.03–1.7).ConclusionsIn a Zambian laboratory, we observed strong agreement between DBS and plasma VLs and high sensitivity in DBS at plasma VL ≥2,000 IU/ml. As HBV treatment expands, DBS could increase access to HBV VL testing and care in SSA settings.     

Comparison of three quantitative HCV RNA assays in samples from HCV genotype 1- or 4-infected patients treated with the NS3/4A protease inhibitor simeprevir

BackgroundMonitoring HCV RNA levels during treatment is an important tool for managing protease-inhibitor-based regimens, and different assays used in clinical practice can impact treatment decisions.ObjectivesThe concordance of three HCV RNA assays was determined, and their impact on treatment decisions assessed using samples from HCV genotype (GT) 1- and GT4-infected patients treated with the NS3/4A inhibitor simeprevir in combination with pegylated interferon-α/ribavirin.Study designPlasma samples collected during the simeprevir Phase III studies QUEST-1 and QUEST-2 (GT1), and RESTORE (GT4) were analyzed with the Roche High-Pure-System COBAS^® TaqMan^® HCV v2.0 (HPS), the Roche AmpliPrep COBAS^® TaqMan^® HCV v2.0 (CAP), and the Abbott RealTime HCV (ART) assay.ResultsIn GT1, of the 440 samples, 81% were undetectable (rapid virological response; RVR) by HPS at Week 4, 76% by CAP and 44% by ART. In GT4 (103 samples), RVR rates were 67% by HPS and 24% by ART. HCV RNA <25 IU/mL at Week 4 was observed for 95–96% and 92% GT1 samples and 86% and 74% GT4 samples by HPS/CAP and ART, respectively. At Week 12, assay concordance for undetectability was high in GT1 and GT4, (95–98% and 93%, respectively).ConclusionsWhile different HCV RNA assays can lead to substantially different RVR rates, a good concordance was observed with a cut-off of 25 IU/mL. Sustained virologic response rates among GT1 patients achieving RVR or <25 IU/mL at Week 4 were high and similar between assays used. At later time points, when viremia is low, assay concordance was high.     

Analytical sensitivity of four HIV combined antigen/antibody assays using the p24 WHO standard

BackgroundThe Common Technical Specifications for HIV-1 p24 assays published in 2009 fixed the lower limit of detection for obtaining C.E. approval at 2 IU/ml against the WHO standard (first international reference, code NIBSC 90/636); it was previously 50 pg/ml. Some recent fourth generation HIV assays that simultaneously detect antigen and antibody are equivalent to p24 assays, but they were mainly evaluated using p24 antigen standards in pg/ml and little is known of their performance with the IU/ml standard.ObjectivesTo evaluate four of the combined serological assays most commonly used for HIV diagnosis in France against the WHO standard in IU/ml.Study designThe analytical sensitivity of four combined p24 antigen and antibody assays (ARCHITECT HIV Ag/Ab Combo, AxSYM HIV Ag/Ab Combo, VIDAS HIV DUO Quick and VIDAS HIV DUO Ultra) and of one p24 assay (VIDAS HIV p24 II) were determined using dilutions of the WHO standard.ResultsFour of the five assays had a lower limit of detection below 2 IU/ml: 1.24 for ARCHITECT Combo, 0.66 for VIDAS DUO Ultra, 0.43 for VIDAS DUO Quick and 0.73 to 1.15 for VIDAS p24, while that of AxSYM was close to 2 (1.94–2.25).ConclusionsWe have provided the first data on the lower limit of detection of HIV combined assays using the IU/ml WHO standard and demonstrated the need for a single international standard for comparing assays. We recommend the use of this approach in medical laboratory to validate on site their methods.     

Potential Value of Vitamin E in Cancer Patients with Venous Access Devices

BackgroundVitamin E has antiplatelet, fibrinolytic and endotoxin properties that may help avoid the problems of occlusion or inability to withdraw blood from port VADs.PurposeDisseminate information about the non-traditional therapeutic use of vitamin E associated with care of Venous Access Devices (VAD) in patients with cancer.MethodologyIn-person focus groups. Sample of 22 cancer patients who had port Venous Access Devices (VAD).FindingsFourteen percent (N = 3) of patients felt that taking vitamin E, 400–800 IU per day orally, in capsule form, avoided the problems of occlusion or inability to withdraw blood from their current VAD.Practice ImplicationsThe effects of vitamin E on occlusion and inability to withdraw blood in caring for patients who have port VADs, requires further investigation.     

Cytomegalovirus load at treatment initiation is predictive of time to resolution of viremia and duration of therapy in hematopoietic cell transplant recipients

BackgroundPreemptive antiviral therapy relies on viral load measurements and is the mainstay of cytomegalovirus (CMV) prevention in hematopoietic cell transplant (HCT) recipients. However, optimal CMV levels for the initiation of preemptive therapy have not been defined.ObjectivesThe objectives of our work were to evaluate the relationship between plasma CMV DNA levels at initiation of preemptive therapy with time to resolution of viremia and duration of treatment.Study designRetrospective analysis of HCT recipients undergoing serial CMV PCR testing between June 2011 and June 2014 was performed.Results221 HCT recipients underwent preemptive therapy for 305 episodes of CMV viremia. Median time to resolution was shorter when treatment was initiated at lower CMV levels (15 days at 135–440 international units (IU)/mL, 18 days at 441–1000 IU/mL, and 21 days at >1000 IU/mL, P < .001). Prolonged viremia lasting >30 days occurred less frequently when treatment was initiated at 135–440 IU/mL compared to 441–1000 IU/mL and >1000 IU/mL (1%, 15%, 24%, P < .001). Median treatment duration was also shorter in the lower viral load groups (28, 34, 37 days, P < .001).ConclusionInitiation of preemptive therapy at low CMV levels was associated with shorter episodes of viremia and courses of antiviral therapy. These data support the utility of initiating preemptive CMV therapy at viral loads as low as 135 IU/mL in HCT recipients.     

Detection and differentiation of HIV-2 using the point-of-care Alere q HIV-1/2 Detect nucleic acid test

BackgroundThe Alere q HIV-1/2 Detect test (Alere Detect) is a rapid point-of-care (POC) nucleic acid test (NAT) that can detect and differentiate HIV-1 and HIV-2 in 25-μL whole blood or plasma samples. The Alere Detect test has been validated for early infant diagnosis of HIV-1 infection, and it is the only POC NAT device currently known to detect HIV-2, which is endemic in West Africa.ObjectivesTo evaluate the sensitivity detecting HIV-2 RNA and the differential performance of the Alere Detect.Study designPlasma samples from non-HIV (n = 4), HIV-1 (n = 22), HIV-2 (n = 111; 29 Group A, 2 Group B) and HIV-1/HIV-2 dually-seropositive (n = 8) participants in Senegal and the United States and HIV-2 reference strains (3 Group A, 1 Group B) were tested by Alere Detect, Abbott RealTime HIV-1 and the University of Washington HIV-2 RNA quantitative (UW HIV-2) assays.ResultsThe Alere Detect correctly differentiated between HIV-1 and HIV-2 in all 80 (100%) patient samples with detectable HIV RNA (n = 20 HIV-1, 60 HIV-2). The overall HIV-2 detection concordance between Alere Detect and the UW HIV-2 assay was 68% (54/80); the concordance improved to 100% (30/30) for samples with HIV-2 RNA >300copies/mL. Neither assay detected HIV-2 RNA in 31 of 111 HIV-2 seropositive samples.ConclusionsThe Alere Detect test is a novel device detecting HIV RNA in clinical samples, and differentiating HIV-1 and HIV-2 with a high level of specificity. It has the potential for use as a rapid HIV-2 NAT-based diagnosis tool in resource-limited settings and to confirm HIV-2 infection for the CDC 4th generation HIV-1/2 diagnostic algorithm.