Elecsys Hepatitis B Surface Antigen Research Articles

Comparison of architect assay and elecsys HBs Ag II assay in the quantification of hepatitis B surface antigen in chronic HBV patients

Background. Hepatitis B virus (HBV) infection is a global health concern, with an estimated 296 million chronic carriers worldwide. Quantification of hepatitis B surface antigen (HBsAg) is a crucial tool in HBV disease management, providing valuable insights into disease progression and treatment efficacy. Objective. To evaluate the comparative performance of the Abbott Architect HBsAg QT and Roche Elecsys HBsAg II assays in quantifying hepatitis B surface antigen (HBsAg) levels in patients with chronic hepatitis B (CHB). Methods. This prospective study enrolled 60 confirmed CHB patients between February 2021 and November 2021. HBsAg levels were measured using both assays and subsequently log-transformed (log10 IU/mL) for statistical analysis. Interclass correlation coefficient (ICC), Pearson correlation coefficient, and Bland-Altman analyses were employed to assess assay concordance and systematic bias. Results. A statistically significant positive correlation was observed between the Elecsys HBsAg II and Architect HBsAg QT assays for both untreated and treatment-receiving CHB patients (ICC values not specified, p <0.001). Notably, Architect consistently yielded higher HBsAg measurements compared to Elecsys. Conclusion. Both the Elecsys HBsAg II and Architect HBsAg QT assays demonstrate robust correlation in quantifying HBsAg levels in CHB patients. However, the Architect assay exhibits a systematic positive bias relative to Elecsys, which should be considered when interpreting results and making clinical decisions. Both tools provide reliable assessments for HBsAg quantification within CHB management strategies, but it is essential to be aware of potential assay-specific differences.

Need for Confirmatory Neutralization Tests for Hepatitis B Surface Antigen Tests in Populations with Intermediate Prevalence.

Hepatitis B surface antigen (HBsAg) is known as the hallmark of hepatitis B virus (HBV) infection. This study aimed to determine whether an HBsAg neutralization test is necessary to accurately interpret HBsAg test results. Initially reactive HBsAg specimens from a 5-year period, with cutoff index values between 1.0 and 2.0, were subjected to neutralization confirmatory testing using an Elecsys HBsAg Confirmatory test kit (Roche Diagnostics GmbH. Mannheim, Germany). The neutralization test showed 46.1% positive (confirmed positive group) and 53.9% negative (confirmed negative group) results from the total specimens. Among the confirmed negative group, 79.5% of patients were confirmed to be negative for the current infection, whereas 4 patients in the chronic hepatitis B subgroup showed a neutralization percentage close to 40%. More than half of patients in the confirmed positive group were considered to be in the hepatitis B e antigen-negative inactive HBsAg carrier phase. In populations with intermediate HBV prevalence, a neutralization test is necessary to confirm an HBsAg result and reduce the false positive and false negative rates of initial HBsAg tests.

Tedavi alan kronik hepatit B hastalarında serum kantitatif HBsAg düzeyi ile viral yük arasındaki ilişkinin araştırılması

Study Aims: The Hepatitis B surface antigen (HBsAg) test was only used for diagnosis of hepatitis B infection, whereas now there is growing evidence favoring utilization of serum HBsAg quantitation (qHBsAg) for monitoring of infection with hepatitis B virus (HBV). In our study, we examined the courses of qHBsAg and HBV-DNA levels throughout the treatment course of patients receiving treatment for chronic hepatitis B infection and evaluated their correlation with each other. Material and Methods: The study was performed Ankara Training and Research Hospital. A total of 71 patients receiving treatment for the diagnosis of chronic hepatitis B (CHB) infection were included in the study. Serum qHBsAg levels of these patients were analyzed with an Elecsys HBsAg II assay. Results: When we evaluated the correlation of serum qHBsAg levels with the HBV-DNA levels among patients treated with nucleotide analogues, there was a positive correlation. The decline in both parameters at sixth and 12 month follow-up was found to be statistically significant (qHBsAg decline at 6th month: p = 0.03; qHBsAg decline at 12th month: p = 0.001; HBV-DNA decline at 6th month: p = 0.001; HBV-DNA decline at12th month: p = 0.001). In the group of patients receiving PEG-IFN treatment, there was positive correlation between the two at the end of the treatment (p = 0.01). Conclusion: Our findings suggest that qHBsAg may be used for both the treatment decision and monitoring of treatment.

A hook-effect-free homogeneous light-initiated chemiluminescence assay: is it reliable for screening and the quantification of the hepatitis B surface antigen?

BackgroundHepatitis B virus (HBV) infection remains a threat to global public health. As a hallmark of HBV infection, hepatitis B surface antigen (HBsAg) has been used to screen for HBV infection for decades, and quantitative assays are also being clinically rejuvenated to predict the disease outcome and monitor the antiviral response. Herein, we developed and evaluated a hook-effect-free homogeneous quantitative HBsAg assay based on the light-initiated chemiluminescence immunoassay (LICA).MethodsA hook-effect-free LICA algorithm was established by measuring the relative light units (RLUs) of two time points during the immunoreaction. The precision was assessed using low- and high-level controls. Consecutive clinical serum samples were tested using the LICA and Abbott Architect assay; samples producing inconsistent results were retested using supplementary assays including the HBsAg neutralization, HBV DNA, and Roche Elecsys HBsAg assays for further confirmation. The consistency, sensitivity, specificity, and positive and negative predictive values (PPV and NPV) were calculated. For the quantitative results, the correlation was analyzed. The coverage of different genotypes and mutations by the LICA was evaluated. Moreover, serial on-treatment and follow-up samples from chronic hepatitis B patients were also measured using the two assays.ResultsThe LICA had better within-run and within-laboratory precisions than the Architect assay. In total, 5,176 clinical samples were tested. The two assays showed a consistency of 99.63%. The LICA showed greater specificity (99.95% vs. 99.77%) and PPV (99.75% vs. 98.77%) than the Architect assay, whereas the Architect assay showed greater sensitivity (100.00% vs. 99.01%) and NPV (100.00% vs. 99.82%). The two assays displayed an excellent correlation independent of genotypes and mutations. The LICA hook-free algorithm recognized 100% of the underestimated results. Furthermore, similar HBsAg dynamics were demonstrated using the LICA and Architect HBsAg assay.ConclusionsThe hook-free LICA provides a reliable tool for screening for HBV infection and quantifying HBsAg.

Proposal of Efficient Workflows for Confirmatory Neutralization Test for Initial Hepatitis B Surface Antigen Positive Samples

Since more sensitive immunoassays have been introduced, false positive Hepatitis B surface antigen (HBsAg) results are increasing. This study was carried out to propose a process to reduce the burden of the laboratory while increasing positive predictive value in HBsAg. Samples with Elecsys HBsAg II (Roche Diagnostics, Germany) between cutoff index (COI) 0.9 and 10.0 were tested with Elecsys HBsAg Confirmatory Test (Roche Diagnostics). If the COI value after neutralization is less than or equal to 60% of the COI treated with control reagent, the sample was determined as HBsAg positive. A total of 133 samples were analyzed and 70.7% were confirmed positive. The highest COI of negatively confirmed sample was 5.6. Receiver operating characteristic curve analysis of HBsAg assay showed an area under curve of 0.761. Specificity was 100% at COI 6.0. Based on this finding, the authors propose that only samples with HBsAg COI less than 6.0 need confirmatory tests.

Development of a Rapid Automated Fluorescent Lateral Flow Immunoassay to Detect Hepatitis B Surface Antigen (HBsAg), Antibody to HBsAg, and Antibody to Hepatitis C.

BackgroundAccurate, rapid, and cost-effective screening tests for hepatitis B virus (HBV) and hepatitis C virus (HCV) infection may be useful in laboratories that cannot afford automated chemiluminescent immunoassays (CLIAs). We evaluated the diagnostic performance of a novel rapid automated fluorescent lateral flow immunoassay (LFIA).MethodsA fluorescent LFIA using a small bench-top fluorescence reader, Automated Fluorescent Immunoassay System (AFIAS; Boditech Med Inc., Chuncheon, Korea), was developed for qualitative detection of hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs), and antibody to HCV (anti-HCV) within 20 minutes. We compared the diagnostic performance of AFIAS with that of automated CLIAs—Elecsys (Roche Diagnostics GmbH, Penzberg, Germany) and ARCHITECT (Abbott Laboratories, Abbott Park, IL, USA)—using 20 seroconversion panels and 3,500 clinical serum samples.ResultsEvaluation with the seroconversion panels demonstrated that AFIAS had adequate sensitivity for HBsAg and anti-HCV detection. From the clinical samples, AFIAS sensitivity and specificity were 99.8% and 99.3% for the HBsAg test, 100.0% and 100.0% for the anti-HBs test, and 98.8% and 99.1% for the anti-HCV test, respectively. Its agreement rates with the Elecsys HBsAg, anti-HBs, and anti-HCV detection assays were 99.4%, 100.0%, and 99.0%, respectively. AFIAS detected all samples with HBsAg genotypes A-F and H and anti-HCV genotypes 1, 1a, 1b, 2a, 2b, 4, and 6. Cross-reactivity with other infections was not observed.ConclusionsThe AFIAS HBsAg, anti-HBs, and anti-HCV tests demonstrated diagnostic performance equivalent to current automated CLIAs. AFIAS could be used for a large-scale HBV or HCV screening in low-resource laboratories or low-to middle-income areas.

Substantial variation in the hepatitis B surface antigen (HBsAg) in hepatitis B virus (HBV)-positive patients from South Africa: Reliable detection of HBV by the Elecsys HBsAg II assay

BackgroundIt is essential that hepatitis B surface antigen (HBsAg) diagnostic assays reliably detect genetic diversity in the major hydrophilic region (MHR) of HBsAg to avoid false-negative results. Mutations in this domain display marked ethno-geographic variation and may lead to failure to diagnose hepatitis B virus (HBV) infection. ObjectivesEvaluate diagnostic performance of the Elecsys® HBsAg II Qualitative assay in a cohort of South African HBV-positive blood donors. Study designA total of 179 South African HBsAg- and HBV DNA > 100 IU/mL-positive blood donor samples were included. Samples were sequenced for genetic variation in HBsAg MHR using next-generation ultra-deep sequencing. HBsAg seropositivity was determined using the Roche Elecsys HBsAg II Qualitative assay. Mutation rates were compared between the first (amino acids 124–137) and second (amino acids 139–147) loops of the immunodominant MHR ‘a’ determinant region. Frequency of occult HBV infection-associated Y100C mutations was also determined. ResultsWe observed a total of 279 MHR mutations (117 variants) in 102 (57%) samples, of which 91 were located in the ‘a’ determinant region. The major vaccine-induced escape mutation G145R was observed in two samples. All occult HBV infection-associated Y100C and common diagnostic and vaccine-escape-associated P120T, G145R, K122R, M133L, M133T, Q129H, G130N, and T126S mutations were reliably detected by the assay, which consistently detected the presence of HBsAg in all 179 samples including samples with 11 novel mutations. ConclusionsDespite substantial variation in HBsAg MHR, the Elecsys HBsAg II Qualitative assay robustly detects HBV infection in this South African cohort.

Serum Hepatitis B Surface Antigen Kinetics in Severe Reactivation of Hepatitis B E Antigen Negative Chronic Hepatitis B Patients Receiving Nucleoside/Nucleotide Analogues

Kinetics of serum hepatitis B surface antigen (HBsAg) level in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B patients presented with severe reactivation and received oral antiviral therapy is unknown. We aimed to investigate the kinetics of HBsAg level among these patients. HBeAg-negative patients on antiviral therapy with follow-up for 2 years were studied. Those presented with severe reactivation (alanine aminotransferase [ALT] ≥5 times of normal) were compared to those with mild hepatitis. Serum HBsAg level was measured by Elecsys HBsAg II Quant assay (Roche) at baseline and 6-monthly. A total of 192 (74 severe reactivation) patients were studied. Eighty-one (42%), 74 (39%) and 37 (19%) patients were on lamivudine, entecavir and telbivudine, respectively. Forty-four (23%) patients had early HBsAg decline, that is, ≥0.5 log10 reduction, at month 6. Patients with severe reactivation had higher serum baseline ALT (1,415 ±897 versus 73 ±39 IU/l), HBV DNA (6.4 ±1.6 versus 5.2 ±1.2 log10 IU/ml) and HBsAg (3.3 ±1.0 versus 2.9 ±0.6 log10 IU/ml), as well as an earlier HBsAg decline (50% versus 6%; all P<0.001) than those without. The HBsAg change of patients with severe reactivation was higher at months 0-6 (-0.58 ±-1.26 versus -0.01 ±-0.26 log10 IU/ml; P<0.001) but then became comparable from months 6-24 (-0.19 ±-0.60 versus -0.13 ±-0.19 log10 IU/ml; P=0.85), compared to those presented with mild hepatitis. Patients who presented with severe reactivation of HBeAg-negative hepatitis were more likely to develop early HBsAg decline during antiviral therapy. It may indicate a transient strong immune clearance with rapid initial reduction in serum HBsAg, which cannot be sustained due to a faster clearance of serum HBsAg.

Elecsys Hepatitis B Surface Antigen Quantitative Assay: Performance Evaluation and Correlation with Hepatitis B Virus DNA during 96 Weeks of Follow-up in Chronic Hepatitis B Patients

BackgroundTreatment for chronic hepatitis B aims to suppress virus replication and virus sequestration in hepatocytes. Covalently closed circular (ccc) DNA is the template for transcription of viral genes and is responsible for viral persistence. However, limited data are available for quantification of hepatitis B surface antigen (HBsAg) in Korea.MethodsWe evaluated the Elecsys HBsAg II quant assay (Roche Diagnostics, USA) for within-run, between-run, and between-day precisions, linearity, carryover, and clinical specificity. In total, 156 serum samples were evaluated for correlation between HBsAg and hepatitis B virus (HBV) DNA. Serial samples were obtained from 10 patients at 0, 12, 24, 48, 72, and 96 weeks during follow-up.ResultsThe assay detected HBsAg in a linear range of 0.5-48,696 IU/mL. Within-run, between-run, and between-day CVs were 2.9-4.1%, 0-1.5%, and 1.5-4.9%, respectively. Cross-reactivity between potentially interfering substances was absent, and the carryover rate was 0.00002%. The correlation of measurements between the Elecsys assay and HBV DNA PCR was weak (r=0.438, P=0.002). For predicting virologic response, cutoff values of 10,275 IU/mL and 3,846 IU/mL at 12 and 24 weeks after treatment initiation showed positive predictive values of 77.1% and 85% and negative predictive values of 84.6% and 50%, respectively.ConclusionsThe Elecsys HBsAg II quant assay showed good performance for precision, linearity, carryover rate, and specificity. HBsAg level at baseline, 12 weeks, and 24 weeks after treatment initiation can predict virologic response, and the assay can be used for HBsAg quantification in clinical practice.

Compare HBsAg cutoff index values of borderline or initially weakly reactive samples with neutralization results for electrochemiluminescence immunoassay in China

To set up arbitrary cutoff values and to determine whether arbitrary cutoff values can be predictive of confirmed positive results by compare cutoff index (COI) values of the borderline or initially reactive samples (0.9≤COI<7.0) with HBsAg confirmation test. 238 HBsAg borderline or initially reactive sera or plasma with 0.9≤COI<7.0 were collected from the clinical patients in West China Hospital of Sichuan University. Each sample must be re-determined in duplicate with Elecsys HBsAg II assay according to manufacturers’ instructions. All repeated reactive samples were confirmed with HBsAg neutralization assay. HBV viral loads were tested if necessary. 116 out of 238 (48.7%) samples, deemed as weakly reactive (WR) samples, were found COIs <2.0. 12.1% (11 out of 91) of WR samples did not pass confirmation in repeated reactive samples. Statistical analysis indicated that much more WR samples were found in HBsAg negative group (100%) than those in repeatedly reactive group (42.7%) (P<0.05). In the 116 WR samples (COI<2.0), 25 samples were HBsAg negative and 11 did not pass the neutralization. 36 WR samples were discovered electrochemiluminescence immunoassay HBsAg negative or confirmed negative. Furthermore, four HBsAg negative and one confirmed negative samples were found HBV DNA existed. 36 WR samples harbored with anti-HBc and anti-Hbe. By setting up modified cutoff values to 1.455 or 1.785, the positive predicted value (PPV) could be improved from 95.2 to 99.4% or 100% in this study. Evaluation of HBsAg prevalence through Elecsys HBsAg II overestimated the true positive, especially in WR samples.Adjusted COIs decreased the need of HBsAg neutralization test, to same degree. Key words: hepatitis B surface antigen (HBsAg), confirmation test,Electrochemiluminescence immunoassay (ECLIA), weakly reactive.

Stability of hepatitis B surface antigen over time: Implications for studies using stored sera

In chronic hepatitis B, quantitative measurements of hepatitis B surface antigen (HBsAg) have been studied increasingly using stored sera to determine its usefulness in disease management. However, the stability of stored HBsAg levels has not been established. The current study determines prospectively the stability of HBsAg levels in sera stored for 1 year. Fresh sera from 105 samples were divided into 5 aliquots. The first aliquot was used to determine HBsAg at the time of blood sampling. The remaining four aliquots were stored at -20°C and thawed at 3, 6, 9, and 12 months to determine the HBsAg levels. HBsAg was measured by adopting the research protocol using the Elecsys HBsAg II assay. At baseline, age and HBV DNA showed a significant correlation with HBsAg levels (r = -0.291, P = 0.003 and r = 0.256, P = 0.003, respectively). There was no overall significant difference observed between the HBsAg levels measured at the different time points. There was high correlation between each consecutive time points from baseline to 3 months, 3-6 months, 6-9 months, and 9-12 months (r = 0.991, 0.987, 0.989, 0.993, respectively, all P < 0.001). The overall log difference in HBsAg levels between baseline and at 12 months was 0.03 (range, -0.29 to 0.85), with over 99% of samples showing no significant change (defined as >1 log) after 12 months. In conclusion, HBsAg levels remained stable in stored frozen sera for 12 months without significant changes, and could be used to quantify HBsAg accurately.

Multicenter Evaluation of the Elecsys Hepatitis B Surface Antigen Quantitative Assay

The Elecsys hepatitis B surface antigen (HBsAg) II quantitative assay is a new quantitative electrochemiluminescence immunoassay which uses onboard dilution and a simple algorithm to determine HBsAg levels expressed in international units (IU)/ml (standardized against the World Health Organization [WHO] Second International Standard). This study evaluated its performance using routine serum samples from a wide range of HBsAg carriers and patients with chronic hepatitis B (CHB). HBsAg levels were measured in serum samples collected independently by five centers in Europe, Australia, and Asia. Serial dilution analyses were performed to assess the recommended dilution algorithm and determine the assay range free of hook effect. Assay precision was also established. Following assessment of serial dilutions (1:100 to 1:1,000,000) of the 611 samples analyzed, 70.0% and 85.6% of samples tested with analyzers incorporating 1:100 (Elecsys 2010 and cobas e 411) and 1:400 (Modular Analytics E170) onboard dilution, respectively, fell within the linear range of the assay, providing a final result on the first test. No high-dose hook effect was seen up to the maximum HBsAg serum level tested (870,000 IU/ml) using the dilution algorithm. HBsAg levels were reliably determined across all hepatitis B virus (HBV) genotypes, phases of HBV infection, and stages of disease tested. Precision was high across all analyzers (% coefficient of variation [CV], 1.4 to 9.6; HBsAg concentrations, 0.1 to 37,300 IU/ml). The Elecsys HBsAg II quantitative assay accurately and reliably quantifies HBsAg in routine clinical samples. Onboard dilution minimizes retesting and reduces the potential for error.

A comparison of two assays for quantification of Hepatitis B surface Antigen in patients with chronic hepatitis B

Background and objectivesSerum Hepatitis B surface Antigen (HBsAg) levels correlate with hepatitis B virus intrahepatic covalently closed circular DNA and may predict response to treatment. Currently, 2 commercial platforms are available for HBsAg quantification in clinical practice, the Architect HBsAg QT and the Elecsys HBsAg. We aimed to directly compare the results of these assays. Study designHBsAg levels were measured in 1427 serum samples from HBeAg-positive chronic hepatitis B patients who participated in a randomized trial of peginterferon alfa-2b±lamivudine. Samples were extracted from our serum bank, thawed, and subsequently analysed for HBsAg levels using both assays. ResultsOf 1427 samples, 242 (17%) were taken before and 1185 during the treatment phase of the study. Distribution of HBV genotypes was 447 (31%) genotype A, 125 (9%) B, 210 (15%) C and 534 (37%) D. Correlation between Architect and Elecsys results was high (r=0.96, p<0.001). By Bland–Altman analysis, agreement between the two assays was close (mean difference between Architect and Elecsys: −0.01logIU/mL, 95% CI: −0.55–0.52logIU/mL), also when analysed separately for HBV genotypes A–D. Additionally, the performance of our recently published stopping rule for HBeAg-positive patients treated with peginterferon was comparable: the negative predictive values were 96% and 98% for Elecsys and Architect, respectively. ConclusionsThere is a high correlation and close agreement between quantitative HBsAg measurements conducted with the Architect and the Elecsys. Clinical prediction rules derived from data from one platform can be applied on the other; both can therefore be used in clinical practice.

Correlation between the Elecsys HBsAg II assay and the Architect assay for the quantification of hepatitis B surface antigen (HBsAg) in the serum

Background Hepatitis B surface antigen (HBsAg) clearance during chronic hepatitis B (CHB) infection is associated with improved long-term clinical outcome, so is considered an important therapeutic goal in CHB. Studies have shown that serum HBsAg quantification during, and at end of, treatment may predict long-term HBsAg loss. Objectives Performance comparison of the qualitative Elecsys HBsAg II assay using a quantitative research protocol and an established quantitative HBsAg assay. Study design A dilution algorithm was developed for the Elecsys HBsAg II assay to allow quantification of HBsAg levels; this was used to measure HBsAg levels in a range of samples including sera from patients infected with different HBV genotypes, HBV mutants, and longitudinal samples from patients undergoing antiviral treatment. Results were compared with those from the quantitative Architect HBsAg assay. Results There was significant overall correlation between Elecsys and Architect assays (correlation coefficient [ r] = 0.97; p < 0.001). HBsAg levels measured with both assays correlated well in all phases of infection ( r = 0.80–0.96), across all genotypes tested (HBV genotype A, r = 0.89; HBV genotype D, r = 0.97), and in samples with lamivudine-resistant mutations ( r = 0.94). Bland–Altman analysis showed only minor discordance between assays in different phases of chronic HBV-infection (3.8–5.1%). This strong correlation was also present for sera with lower HBsAg concentrations. On-treatment HBsAg levels were similar when measured with either assay. Conclusions Using a simple dilution algorithm, the quantitative Elecsys HBsAg II assay reliably determined serum HBsAg levels in a wide range of samples, and showed very high correlation with the Architect HBsAg assay.

Comparison of Nine Different Qualitative HBsAg Assay Kits

Qualitative hepatitis B surface antigen (HBsAg) assay kits are still commonly used in Korea where hepatitis B virus (HBV) infection is endemic. The accurate determination of HBsAg plays a crucial role in the diagnosis and prevention of HBV infection, especially in endemic areas. The aim of this study was to compare the detection sensitivities of 9 qualitative HBsAg assay kits. Seven pooled sera with HBsAg concentration ranging from 0.14 IU/mL to 29.96 IU/mL were prepared. The HBsAg concentration of each pooled serum was determined by a quantitative HBsAg assay, Architect HBsAg (Abbott Laboratories, Ireland). The fully automated immunoassay kits included Elecsys HBsAg (Roche Diagnostics, Germany) and Immulite 2000 HBsAg (DPC, USA) and the rapid tests included 5 immunochromatographic assay (ICA) kits and 2 reverse passive hemagglutination assay (RPHA) kits. Elecsys HBsAg (Roche Diagnostics) showed positive result in pooled serum with HBsAg concentration of 0.14 IU/mL, but Immulite 2000 HBsAg (DPC) showed negative result in the same concentration. Although ICA kits showed variable results among different assay kits, all of them showed negative results in pooled sera with HBsAg concentration of < or = 1.89 IU/mL. Two RPHA kits showed negative results in pooled sera with HBsAg concentration of < or = 7.98 IU/mL. Although ICAs were more sensitive than RPHAs, they had variable sensitivities for HBsAg and were less sensitive than the automated immunoassay kits. Therefore, ICAs and RPHAs should be used with caution in the screening tests for HBsAg and their sensitivities need to be improved.

Comparison of the technical and clinical performance of the Elecsys® HBsAg II assay with the Architect®, AxSym®, and Advia® Centaur HBsAg screening assays

South East Asia has some of the highest prevalence rates of hepatitis B virus (HBV) infection (>or=8%) in the world, and the emergence of hepatitis B surface antigen (HBsAg) mutant strains is a growing problem. Assays with the highest levels of sensitivity, including mutant detection, should be used for routine HBsAg screening. In this large multicenter study, the clinical and technical performance of the fully automated Elecsys HBsAg II assay was compared with the Architect, AxSYM, and Advia Centaur HBsAg assays for HBsAg screening. Nine laboratories (three each from Thailand, Korea, and Singapore) compared the Elecsys HBsAg II assay with their routine HBsAg screening assay against a range of stored and routine clinical samples, including recombinant mutants. The Elecsys HBsAg II assay demonstrated equivalent sensitivity and specificity to the Architect HBsAg assay. However, the Elecsys HBsAg II assay recognized a native mutant sample (L94S, L97V, L98V, T123A) that the Architect HBsAg assay failed to detect. The AxSYM and Advia Centaur HBsAg assays appeared less sensitive for the detection of early HBV infection and also failed to detect some of the recombinant mutant strains. There was almost complete agreement between the Elecsys HBsAg II assay and comparator assays with respect to routine serum samples. The results of this study demonstrate that the Elecsys HBsAg II assay is a highly sensitive and specific screening assay for HBsAg and detects reliably the most important and clinically relevant HBV mutants and genotypes. It is suitable for routine HBsAg screening in Asia.

Multicentre evaluation of the Elecsys® hepatitis B surface antigen II assay for detection of HBsAg in comparison with other commercially available assays

Screening for hepatitis B surface antigen (HBsAg) demands highly sensitive and specific immunoassays with the ability to detect clinically relevant surface gene mutants-the presence of which is an increasing concern and can compromise test results. The objective of the study was to compare the clinical and technical performance of the fully automated Elecsys HBsAg II assay with other widely used HBsAg immunoassays in China. This was a multicentre study in which eight Chinese laboratories compared the Elecsys HBsAg II assay with the Architect HBsAg assay, AxSYM HBsAg assay, or generic microtitre plate (MTP) enzyme-linked immunosorbent assays (manufactured in China) against preselected samples, including recombinant surface gene mutants, and routine clinical samples. Elecsys HBsAg II was the most sensitive assay for detecting positive results in seroconversion samples: up to 14, 11, and 22 days earlier than the Architect, AxSYM, and MTP HBsAg assays, respectively. It also detected all 211 preselected HBsAg-positive specimens and all 13 recombinant HBsAg mutants; the AxSYM and MTP HBsAg assays failed to detect 3 and 10 mutant samples, respectively. Sensitivity was 100% for Elecsys HBsAg II with routine samples, compared with 99.1, 98.9, and 95.2% for the Architect, AxSYM, and MTP HBsAg assays, respectively. In conclusion, it was demonstrated that the Elecsys HBsAg II assay is suitable for routine HBsAg screening in China.