Evaluation of a new automated assay for hepatitis B surface antigen (HBsAg) detection VIDAS HBsAg Ultra

Does the ultrasensitive HBsAg Next assay enhance Hepatitis B diagnosis? An evaluation of analytical performances

BACKGROUND

Accurate laboratory confirmation for Hepatitis B diagnosis and monitoring are crucial. Recently an ultrasensitive immunoassay test, the HBsAg Next (HBsAgNx), has been reported approximately eight times more sensitive than current HBsAg assays. The aim of our study was to assess the analytical performances of this new test.

METHODOLOGY

253 clinical samples from Saint Louis University Hospital were analyzed, splitted into four panels: (1) routine prospectively screening serums (n = 196), (2) retrospective serum samples before HBV reactivation (HBV-R) (n = 18), (3) occult HBV infection (OBI) (n = 10) and (4) a selection of wild type HBV genotypes (n = 29) RESULTS: Panel 1, showed robust agreement with the HBsAg Qualitative II (HBsAgQII) assay (Cohen's kappa = 0.83). Despite this agreement, 7 false positive with the HBsAgQII assay were found negative with HBsAgNx. One OBI was detected only with HBsAgNx. Panel 2 showed potential time savings in diagnosing HBV-R using HBsAgNx among 4/18 HBsAg positives samples. Panel 3 highlighted the ability of HBsAgNx to detect HBsAg in OBI patients defined by negative for HBsAg with HBsAgQII assay and positive for HBV DNA. Furthermore, the HBsAgNx assay detected all different genotypes.

CONCLUSION

The study highlights the effectiveness of the HBsAgNx assay, showing its performance. It excels in detecting weakly positive samples and addressing challenging cases. HBsAgNx assay demonstrates promising analytical performances, with improved sensitivity and specificity compared to standard HBsAgQII assay, able to detect all genotypes. Its potential impact on early detecting and monitoring reactivations, and occult infections could be very useful in clinical practice.

Biomarkers of transfusion transmitted occult hepatitis B virus infection: Where are we and what next?

Blood transfusion is a vital procedure, where transfusion-transmitted infection of hepatitis B virus (HBV) remains an important issue, especially from blood donors with occult hepatitis B virus infection (OBI). Occult hepatitis B virus infection is a complex entity to detect using surrogate blood biomarkers for intrahepatic viral transcriptional activity, requiring a continually refined battery of tests utilised for screening. This review aims to critically evaluate the latest advances in the current blood biomarkers to guide the identification of OBI donors and discuss novel HBV markers that could be introduced in future diagnostic practice. Challenges in detecting low HBV surface antigen levels, mutants, and complexes necessitate ultrasensitive multivalent dissociation assays, whilst HBV DNA testing requires improved sensitivity but worsens inaccessibility. Anti-core antibody assays defer almost all potentially infectious donations but have low specificity, and titres of anti-surface antibodies that prevent infectivity are poorly defined with suboptimal sensitivity. The challenges associated with these traditional blood HBV markers create an urgent need for alternative biomarkers that would help us better understand the OBI. Emerging viral biomarkers, such as pre-genomic RNA and HBV core-related antigen, immunological HBV biomarkers of T-cell reactivity and cytokine levels, and host biomarkers of microRNA and human leucocyte antigen molecules, present potential advances to gauge intrahepatic activity more accurately. Further studies on these markers may uncover an optimal diagnostic algorithm for OBI using quantification of various novel and traditional blood HBV markers. Addressing critical knowledge gaps identified in this review would decrease the residual risk of transfusion-transmitted HBV infection without compromising the sustainability of blood supplies.

Atypical serologic profiles of hepatitis B virus infection across clinical cohorts of patients in Southwestern Nigeria

Hepatitis B virus (HBV) infection follows a natural course of events predicted by a dynamic interaction between viral antigen and the host immune system, which forms the basis for HBV serological diagnosis. These interactions may deviate from the typical serologic patterns. This study investigates the types of atypical HBV serologic profiles (AHBSP) across clinical cohorts of patients with HBV infection in southwestern Nigeria. This is a cross-sectional, hospital-based, multi-centered study. Patients' sera were analyzed for HBsAg, anti-HBs, HBeAg, anti-HBe, anti-HBc IgM, and anti-HBc IgG by ELISA from 279 study participants attending selected gastroenterology clinics between August 2019 and December 2020. The prevalence of atypical HBV serologic profiles was 27% (n = 76). The mean age of patients was 35.7 ± 11.2 years. The gender distribution involved 183 females (65.6%) and 96 males (34.4%). Across clinical cohorts of patients with atypical serologic profiles, HBeAg Negative, anti-HBe positive with detectable HBV DNA had the highest prevalence of 21% followed by isolated anti-HBc antibody positive, HBsAg negative and detectable HBV DNA, 5%. The atypical serologic profiles, HBeAg positive, HBsAg negative with detectable HBV DNA and concurrent anti-HBs with HBsAg, had the lowest prevalence, 0.4%, respectively. This study identified the considerable presence of atypical HBV serologic profiles across clinical cohorts of HBV infection in southwestern Nigeria.

A new vaccine escape mutant of hepatitis B virus causes occult infection

There is growing public concern regarding assay sensitivity to HBsAg mutants in clinical diagnosis and vaccine escape. The aim of this study is to introduce a new HBsAg mutant strain. The serum samples were those of patient X at the age of 3 months and 3 years respectively, and of her mother immediately before parturition, which were used to amplify the HBsAg-coding DNA fragments by PCR. The HBsAg DNA sequences were translated into their corresponding amino acid sequences and then aligned in pubmed with nucleotide blast. The sequencing data of S coding regions shows that patient X has been infected by a new HBV variant with an A to C substitution at nt431, resulting in an Asp(GAC)to Ala(GCC) substitution at aa144 of major protein; CC to AA substitution at nt359 and nt360, resulting in an Pro(CCC) to Gln(CAA) substitution at aa120 of pre "a" epitope; A to G substitution at nt491, resulting in an Glu(GAG) to Gly(GGG) substitution at aa164 of post "a" epitope. Three new mutations (S171F, S174N and Q181R) at the antigenic epitopes of HBV presented by HLA class I molecules are found. The HBV mutant strain causes vaccine escape and occult infection.

Detection of hepatitis B virus infection: A systematic review

AIM: To review published methods for detection of hepatitis B virus (HBV) infection.

METHODS: A thorough search on Medline database was conducted to find original articles describing different methods or techniques of detection of HBV, which are published in English in last 10 years. Articles outlining methods of detection of mutants or drug resistance were excluded. Full texts and abstracts (if full text not available) were reviewed thoroughly. Manual search of references of retrieved articles were also done. We extracted data on different samples and techniques of detection of HBV, their sensitivity (Sn), specificity (Sp) and applicability.

RESULTS: A total of 72 studies were reviewed. HBV was detected from dried blood/plasma spots, hepatocytes, ovarian tissue, cerumen, saliva, parotid tissue, renal tissue, oocytes and embryos, cholangiocarcinoma tissue, etc. Sensitivity of dried blood spot for detecting HBV was > 90% in all the studies. In case of seronegative patients, HBV DNA or serological markers have been detected from hepatocytes or renal tissue in many instances. Enzyme linked immunosorbent assay and Chemiluminescent immunoassay (CLIA) are most commonly used serological tests for detection. CLIA systems are also used for quantitation. Molecular techniques are used qualitatively as well as for quantitative detection. Among the molecular techniques version 2.0 of the CobasAmpliprep/CobasTaqMan assay and Abbott’s real time polymerase chain reaction kit were found to be most sensitive with a lower detection limit of only 6.25 IU/mL and 1.48 IU/mL respectively.

CONCLUSION: Serological and molecular assays are predominant and reliable methods for HBV detection. Automated systems are highly sensitive and quantify HBV DNA and serological markers for monitoring.

[Evaluation of HBs Ag, HCV and HIV Ag-Ab Assays using Bio-Rad Elite Microplate Analyzer.]

BACKGROUND

In this study, we evaluated the performance of Elite microplate analyzer (Bio-Rad Laboratories, France) and the related assays (ULTRA line) for the detection of hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV).

METHODS

Seroconversion panels, HBsAg positive/HBsAg negative (n=99/n=1,422), anti-HCV positive/negative (n=97/n=1,670), and anti-HIV positive/negative (n=112/n=1,704) samples were used to evaluate the performance of Monolisa HBsAg ULTRA, Monolisa HCV Ag-Ab ULTRA, and Genscreen ULTRA HIV Ag-Ab, respectively. The agreement of Elite microplate analyzer with CODA analyzer (Bio-Rad Laboratories, CA, USA) was also evaluated.

RESULTS

The detection limit of Monolisa HBsAg ULTRA was 0.034 IU/mL. For Monolisa HBsAg ULTRA, Monolisa HCV Ag-Ab ULTRA, and Genscreen ULTRA HIV Ag-Ab, diagnostic sensitivities were all 100%, diagnostic specificities were 100%, 99.8% and 99.9%, and total CVs (coefficients of variation) were 13.8-17.5%, 3.4-5.2%, and 7.5-9.5%, respectively. The agreement of Elite microplate analyzer with CODA analyzer was 99.5%.

CONCLUSIONS

The performance of Elite microplate analyzer and the related assays on analytical sensitivity, precision, early detection, diagnostic sensitivity and specificity was all adequate for a mass screening. However, further large multi-center studies should be performed to validate our results.

HBsAg variants: diagnostic-escape and diagnostic dilemma

A wide variety of commercial assays is available for the detection of hepatitis B surface antigen (HBsAg). Clearly, the sensitivity of an assay to detect a variant is dependent on the anti-HBs usage. Thus, it is not surprising that there are examples of variants that cannot be detected by all assays. Data from Europe, Asia and Africa about HBsAg variants which are not recognized by either monoclonal or polyclonal antibodies specific for wild-type group 'a' determinant, but positive by DNA polymerase chain reaction (PCR) in chronic patients and from vaccinated children are increasing. This would impose a challenge for public health issues of hepatitis B virus. In this review we tried to summarize the discrepancies between results of HBsAg assays and to explain some rationales for these inconsistencies.

Molecular mechanisms underlying occult hepatitis B virus infection

Chronic hepatitis B virus (HBV) infection is a complex clinical entity frequently associated with cirrhosis and hepatocellular carcinoma (HCC). The persistence of HBV genomes in the absence of detectable surface antigenemia is termed occult HBV infection. Mutations in the surface gene rendering HBsAg undetectable by commercial assays and inhibition of HBV by suppression of viral replication and viral proteins represent two fundamentally different mechanisms that lead to occult HBV infections. The molecular mechanisms underlying occult HBV infections, including recently identified mechanisms associated with the suppression of HBV replication and inhibition of HBV proteins, are reviewed in detail. The availability of highly sensitive molecular methods has led to increased detection of occult HBV infections in various clinical settings. The clinical relevance of occult HBV infection and the utility of appropriate diagnostic methods to detect occult HBV infection are discussed. The need for specific guidelines on the diagnosis and management of occult HBV infection is being increasingly recognized; the aspects of mechanistic studies that warrant further investigation are discussed in the final section.

Molecular mechanisms underlying occult hepatitis B virus infection

Chronic hepatitis B virus (HBV) infection is a complex clinical entity frequently associated with cirrhosis and hepatocellular carcinoma (HCC). The persistence of HBV genomes in the absence of detectable surface antigenemia is termed occult HBV infection. Mutations in the surface gene rendering HBsAg undetectable by commercial assays and inhibition of HBV by suppression of viral replication and viral proteins represent two fundamentally different mechanisms that lead to occult HBV infections. The molecular mechanisms underlying occult HBV infections, including recently identified mechanisms associated with the suppression of HBV replication and inhibition of HBV proteins, are reviewed in detail. The availability of highly sensitive molecular methods has led to increased detection of occult HBV infections in various clinical settings. The clinical relevance of occult HBV infection and the utility of appropriate diagnostic methods to detect occult HBV infection are discussed. The need for specific guidelines on the diagnosis and management of occult HBV infection is being increasingly recognized; the aspects of mechanistic studies that warrant further investigation are discussed in the final section.

Comparison of two immunoassays for determining hepatitis B virus serum markers

BACKGROUND

To evaluate and compare the detection efficacy of serum hepatitis B virus (HBV) markers by two immunoassays: electrochemiluminescence immunoassay (ECLIA) and enzyme-linked immunosorbent assay (ELISA).

METHODS

ECLIA and ELISA were used to analyze 359 serum samples, including 64 HBsAg/anti-HBs coexistence serological pattern samples (samples positive for both HBsAg and anti-HBs), 24 HBeAg/anti-HBe coexistence serological pattern samples (samples positive for both HBeAg and anti-HBe), and 271 normal serological pattern samples (negative for either of the combinations).

RESULTS

In the normal serological pattern samples, the concordance rates of the two methods in detecting serum HBV markers were as follows: 97.05% for HBsAg, 92.62% for anti-HBs, 100% for HBeAg, 76.75% for anti-HBe, and 58.67% for anti-HBc. The differences in the qualitative criteria for anti-HBc and anti-HBe were primarily responsible for the discrepancy between the two methods (κ-values of 0.657 and 0.253, respectively). Most weak positive results, determined by ECLIA, were negative determined by ELISA, whereas the results of HBsAg, anti-HBs, and HBeAg detection were generally consistent. In the HBsAg/anti-HBs coexistence serological pattern samples, the concordance rates of HBsAg and anti-HBs detection were 98.44% and 34.38%, respectively. The positive rate of ELISA does not vary as the COI (cut-off index) varies which was determined by ECLIA; in the HBeAg/anti-HBe coexistence serological pattern samples, the concordance rates of HBeAg and anti-HBe detection were 45.83% and 79.17%, respectively. Most weak positive results, determined by ECLIA, were negative when determined by ELISA.

CONCLUSION

The discrepancies between the two assays in normal serological patterns samples and HBeAg/anti-HBe coexistence serological pattern samples were mostly due to the different sensitivity of the two assays, but for the HBsAg/anti-HBs coexistence serological pattern samples, the discrepancy was not caused by the different sensitivity. It is the difference in determining anti-HBs which led to the discrepancy.

[HBsAg quantification: virological significance]

HBsAg is a classic marker of hepatitis B virus infection. Since the levels of serum HBsAg are correlated to those of intrahepatic cccDNA, HBsAg quantification indirectly reflects the number of infected hepatocytes. The kinetics of serum HBsAg decline seems to be a predictive marker for sustained virological response, and clearance of HBsAg. This new tool may be clinically relevant for the monitoring and optimization of hepatitis B treatments. To fulfill this objective, prospective studies are still warranted for the the spread of sensitive and standardized techniques standardization of the quantification assays and to define cut off values with clinical predictive values.

Should patients with abnormal liver function tests in primary care be tested for chronic viral hepatitis: cost minimisation analysis based on a comprehensively tested cohort

Background

Liver function tests (LFTs) are ordered in large numbers in primary care, and the Birmingham and Lambeth Liver Evaluation Testing Strategies (BALLETS) study was set up to assess their usefulness in patients with no pre-existing or self-evident liver disease. All patients were tested for chronic viral hepatitis thereby providing an opportunity to compare various strategies for detection of this serious treatable disease.

Methods

This study uses data from the BALLETS cohort to compare various testing strategies for viral hepatitis in patients who had received an abnormal LFT result. The aim was to inform a strategy for identification of patients with chronic viral hepatitis. We used a cost-minimisation analysis to define a base case and then calculated the incremental cost per case detected to inform a strategy that could guide testing for chronic viral hepatitis.

Results

Of the 1,236 study patients with an abnormal LFT, 13 had chronic viral hepatitis (nine hepatitis B and four hepatitis C). The strategy advocated by the current guidelines (repeating the LFT with a view to testing for specific disease if it remained abnormal) was less efficient (more expensive per case detected) than a simple policy of testing all patients for viral hepatitis without repeating LFTs. A more selective strategy of viral testing all patients for viral hepatitis if they were born in countries where viral hepatitis was prevalent provided high efficiency with little loss of sensitivity. A notably high alanine aminotransferase (ALT) level (greater than twice the upper limit of normal) on the initial ALT test had high predictive value, but was insensitive, missing half the cases of viral infection.

Conclusions

Based on this analysis and on widely accepted clinical principles, a "fast and frugal" heuristic was produced to guide general practitioners with respect to diagnosing cases of viral hepatitis in asymptomatic patients with abnormal LFTs. It recommends testing all patients where a clear clinical indication of infection is present (e.g. evidence of intravenous drug use), followed by testing all patients who originated from countries where viral hepatitis is prevalent, and finally testing those who have a notably raised ALT level (more than twice the upper limit of normal). Patients not picked up by this efficient algorithm had a risk of chronic viral hepatitis that is lower than the general population.

Infection with hepatitis B and C viruses and risk of lymphoid malignancies in the European Prospective Investigation into Cancer and Nutrition (EPIC)

BACKGROUND

Case-control studies suggested a moderate, but consistent, association of hepatitis C virus (HCV) infection with lymphoid tissue malignancies, especially non-Hodgkin lymphoma (NHL). More limited data suggested that hepatitis B virus (HBV) infection might also be associated with NHL. However, prospective studies on the topic are few.

METHODS

A nested case-control study was conducted in eight countries participating in the EPIC prospective study. Seven hundred thirty-nine incident cases of NHL, 238 multiple myeloma (MM), and 46 Hodgkin lymphoma (HL) were matched with 2,028 controls. Seropositivity to anti-HCV, anti-HBc, and HBsAg was evaluated and conditional logistic regression was used to estimate odds ratios (OR) and corresponding 95% confidence intervals (CI) for NHL, MM, or HL, and their combination.

RESULTS

Anti-HCV seropositivity among controls in different countries ranged from 0% to 5.3%; HBsAg from 0% to 2.7%; and anti-HBc from 1.9% to 45.9%. Similar nonsignificant associations were found with seropositivity to HBsAg for NHL (OR = 1.78; 95% CI: 0.78-4.04), MM (OR = 4.00; 95% CI: 1.00-16.0), and HL (OR = 2.00; 95% CI: 0.13-32.0). The association between HBsAg and the combination of NHL, MM, and HL (OR = 2.21; 95% CI: 1.12-4.33) was similar for cancer diagnosed less than 3 and 3 or more years after blood collection. No significant association was found between anti-HCV and NHL, MM, or HL risk, but the corresponding CIs were very broad.

CONCLUSIONS

Chronic HBV infection may increase the risk of lymphoid malignancies among healthy European volunteers.

IMPACT

Treatment directed at control of HBV infection should be evaluated in HBsAg-seropositive patients with lymphoid tissue malignancies.

Prevalence of hepatitis B virus MHR mutations and their correlation with genotypes and antiviral therapy in chronically infected patients in Serbia

Understanding the prevalence and diversity of HBsAg variants in a population is fundamental to assay design and planning vaccination programs. It has been shown that mutations within the S gene, caused by selection or natural variation, can lead to false-negative results in assays for HBsAg, or have clinical implications, such as evading anti-HBV immunoglobulin therapy or vaccine-induced immunity. The region of HBsAg where most of these mutations occur is known as the major hydrophilic region (MHR). The aim of this study was to determine the prevalence and mutational patterns of MHR mutations in patients with chronic hepatitis B, and their correlation with patient characteristics, viral factors and antiviral therapy. The study comprised 164 plasma samples from patients with chronic hepatitis B, of which, 34.8% were on long-term lamivudine monotherapy. Direct sequencing of part of the S/pol gene was used for identification of HBsAg mutations, HBV genotypes, subgenotypes and HBsAg subtypes. The overall frequency of MHR mutations was 22.6%, but it varied significantly between untreated and treated patients (16.8% vs. 33.3%). The most frequent substitution was at position 120 (9.1%) whereas the most common vaccine-escape position, 145, was affected in 1.8% of isolates. The presence of MHR mutations was correlated with genotype D, subgenotype D3, and ayw2/ayw3 HBsAg subtypes and to older age (>40 years). It is concluded that natural viral variability present in a geographical region, duration of infection, and antiviral therapy are among the major factors associated with the occurrence of MHR mutations.

Concordance between two enzyme immunoassays for the detection of Clostridium difficile toxins

BACKGROUND AND AIMS

The diagnosis of Clostridium difficile-associated disease (CDAD) is based on the detection of toxins from stool samples. There are several immunoassays for this purpose. The aim of this study was to determine the concordance between the two immunoassays and their performance in comparison to the toxigenic culture as part of the initial evaluation of a suspected case of CDAD.

METHODS

All fecal samples submitted for detection of C. difficile toxins during a 5-month period to our laboratory were analyzed by two immunoassays, VIDAS Toxin CDA/B assay (BioMerieux) and ImmunoCard Toxins A/B (Meridian Bioscience). We cultured on cycloserine-cefoxitin-fructose agar and PCR was used for detection of toxigenic genes. Real-time PCR was performed directly from samples to detect the tcdC gene.

RESULTS

At the end of the study we processed 230 samples, 13 were positive using VIDAS CDA/B (5.6%), and 14 using ImmunoCard A/B (6.0%); kappa coefficient was 0.857. With ImmunoCard A/B we obtained a sensitivity of 80%, a specificity of 99%, positive predictive value (PPV) 86% and negative predictive value (NPV) 98%, as compared to toxigenic culture. For VIDAS CDA/B we obtained a sensitivity of 90%, a specificity of 98%, PPV 69% and NPV 99%, compared to the same standard. There were seven undetermined results (3.0%) by VIDAS CDA/B. Five of these had a positive culture and all the patients had symptoms of CDAD. Considering these undetermined results as positive, we calculated a sensitivity of 93%, specificity of 97%, PPV 71% and NPV of 99% for this test, and a kappa of 0.856. Both immunoassays showed similar results and are suitable for the initial evaluation of patients with suspected CDAD.

CONCLUSIONS

Our data suggest that an undetermined result of VIDAS CDA/B should be considered as positive if CDAD is suspected. Additionally, both immunoassays showed similar results and are suitable for the initial evaluation of patients with suspected CDAD.

The underlying mechanisms for the "isolated positivity for the hepatitis B surface antigen (HBsAg)" serological profile

During HBV infection, four structural antigen/antibody systems are observed: hepatitis B surface antigen (HBsAg) and its antibody (anti-HBs); the pre-S antigens associated with HBsAg particles and their antibodies; the particulate nucleocapsid antigen (HBcAg) and anti-HBc; and an antigen structurally related to HBcAg, namely HBeAg and its antibody (anti-HBe). Through the examination of this antigen-antibodies system, hepatitis B infection is diagnosed and the course of the disorder may be observed. Isolated HBsAg seropositivity is a peculiar serological pattern in HBV infection observed some times in routine laboratory. In most cases is not clear how this profile should be interpreted neither its significance. This pattern, however, may be associated with some clinical and laboratorial situations of great relevance, some of which will be addressed in this article.

Detection of hepatitis B virus markers using a biosensor based on imaging ellipsometry

A biosensor based on imaging ellipsometry (BIE) has been developed and validated in 169 patients for detecting five markers of hepatitis B virus (HBV) infection. The methodology has been established to pave the way for clinical diagnosis, including ligand screening, determination of the sensitivity, set-up of cut-off values (CoVs) and comparison with other clinical methods. A matrix assay method was established for ligand screening. The CoVs of HBV markers were derived with the help of receiver operating characteristic curves. Enzyme-linked immunosorbent assay (ELISA) was the reference method. Ligands with high bioactivity were selected and sensitivities of 1 ng/mL and 1 IU/mL for hepatitis B surface antigen (HBsAg) and surface antibody (anti-HBs) were obtained respectively. The CoVs of HBsAg, anti-HBs, hepatitis B e antigen, hepatitis B e antibody and core antibody were as follows: 15%, 18%, 15%, 20% and 15%, respectively, which were the percentages over the values of corresponding ligand controls. BIE can simultaneously detect up to five markers within 1 h with results in acceptable agreement with ELISA, and thus shows a potential for diagnosing hepatitis B with high throughput.

Diagnosis and management of chronic viral hepatitis: antigens, antibodies and viral genomes

Virological tools, including serological and molecular tools, are needed to diagnose chronic hepatitis B and C infections. They may also be useful to establish their prognosis, but they have found their principal application in guiding treatment decisions and assessing the virological responses to therapy. The goal of chronic hepatitis B therapy is to prevent progression of liver disease. This is achieved if HBV replication is durably abolished or significantly reduced. In HBeAg-positive patients, HBeAg clearance followed by the HBe seroconversion phase can be achieved. In HBeAg-negative patients, long-term antiviral suppression of viral replication is needed. The loss of HBsAg, eventually associated with an HBs seroconversion, is the most desirable endpoint of therapy but is rarely achieved. The efficacy endpoint of chronic hepatitis C treatment is the sustained virological response, defined by an undetectable HCV RNA in serum with a sensitive assay 24 weeks after the end of treatment. The HCV genotype and on-treatment viral kinetics can be used to tailor treatment dosages and duration.

Diagnosis of human hepatitis B virus in non-treated blood by the bovine IgG DNA-linked carbon nanotube biosensor

OBJECTIVES

To identify an effective bioassay for human hepatitis B virus (HBV) using voltammetric sensor.

STUDY DESIGN

Electrode was prepared with bovine IgG immobilized onto a DNA-linked carbon nanotube electrode (BIDCE). Analytical BIDCE conditions were optimized through square wave (SW) stripping and cyclic voltammetry (CV).

RESULTS

Optimum parameters of 75 Hz SW frequency, 0.1 V SW amplitude, -1.3 V SW accumulation potential, 100 s accumulation time, and 3.0 mV SW increment potential were obtained. Within working ranges of 0.035-0.242 mg/mL anti-bovine IgG, the relative standard deviation of 0.2 mL HBV was observed to be 0.04 (n=4).

CONCLUSIONS

Diagnostic application was performed through direct assay of HBV in non-treated human blood.

Improved detection of natural hepatitis B virus surface antigen (HBsAg) mutants by a new version of the VITROS HBsAg assay

The sensitivity of immunoassays for hepatitis B virus (HBV) surface antigen (HBsAg) detection may be hampered by the presence of mutants involving the major antigenic determinant of the protein. The performance of the VITROS HBsAg Assay has been shown to be affected by mutations comprising amino acid changes at residues 143, 144, and 145 of the HBsAg molecule. Sixty-seven serum samples from HBV carriers containing major populations of natural HBsAg mutants assayed previously by that assay were tested by the new VITROS HBsAg ES Assay. Samples displayed either single or multiple amino acid substitutions between positions 112 and 145 of the HBsAg, including changes in relevant residues such as 118-120, 125-127, and 143-145. Testing of undiluted samples by the current assay gave rise to false negative results in two samples displaying the single substitutions 145A and 145R, and in one additional sample displaying a dual mutation 118A + 145A. Unusually weak reactivity (<25 S/CO units) was, in addition, recorded in samples containing mutants 143L (2 samples) and 115N + 120Q + 131K + 144A (1 sample). Testing samples at the 1/40 dilution by the modified assay did not produce, in contrast, false negative results, and reactivity below 25 S/CO units was recorded only in three cases. These results confirm that the capability of immunoassays to detect the presence of natural HBsAg mutants in clinical samples may be improved significantly by introducing changes in their design, and show that such improvement has been achieved successfully with the new VITROS HBsAg ES Assay.

Multicenter study of a new fully automated HBsAg screening assay with enhanced sensitivity for the detection of HBV mutants

In a multicenter study a new, fully automated Roche Diagnostics Elecsys HBsAg II screening assay with improved sensitivity to HBsAg mutant detection was compared to well-established HBsAg tests: AxSYM HBsAg V2 (Abbott), Architect HBsAg (Abbott), Advia Centaur HBsAg (Bayer) Enzygnost HBsAg 5.0 (Dade-Behring), and Vitros Eci HBsAg (Ortho). A total of 16 seroconversion panels, samples of 60 HBsAg native mutants, and 31 HBsAg recombinant mutants, dilution series of NIBSC and PEI standards, 156 HBV positive samples comprising genotypes A to G, 686 preselected HBsAg positive samples from different stages of infection, 3,593 samples from daily routine, and 6,360 unselected blood donations were tested to evaluate the analytical and clinical sensitivity, the detection of mutants, and the specificity of the new assay. Elecsys HBsAg II showed a statistically significant better sensitivity in seroconversion panels to the compared tests. Fifty-seven out of 60 native mutants and all recombinant mutants were found positive. Among 156 HBV samples with different genotypes and 696 preselected HBsAg positive samples Elecsys HBsAg II achieved a sensitivity of 100%. The lower detection limit for NIBSC standard was calculated to be 0.025 IU/ml and for the PEI standards ad and ay it was <0.001 and <0.005 U/ml, respectively. Within 2,724 daily routine specimens and 6.360 unselected blood donations Elecsys HBsAg II showed a specificity of 99.97 and 99.88%, respectively. In conclusion the new Elecsys HBsAg II shows a high sensitivity for the detection of all stages of HBV infection and HBsAg mutants paired together with a high specificity in blood donors, daily routine samples, and potentially interfering sera.

Hepatitis B virus genotype E surface antigen detection with different immunoassays and diagnostic impact of mutations in the preS/S gene

The major neutralizing epitope, the "a" determinant of the hepatitis B virus (HBV) genotype E surface antigen (HBsAg) is most divergent from that of genotype A, which is used for preparing monoclonal antibodies used in commercially available HBV reagents. To evaluate the performance of the latest generation of HBsAg detection assays with respect to genotype E HBsAg. Three commercial assays were evaluated using sera from 200 Nigerian patients compared to the preS/S sequence of DNA positive samples. Out of 200 samples, 61 and 103 gave concordant positive and negative results between the three HBsAg assays. Of 36 samples with discordant results, 35 were confirmed negative by neutralisation. One of the three assays showed significantly high rate of false positives (29 of 35). DNA positive samples with no detectable HBsAg or reduced HBsAg detection signals (<75% of mean signal obtained with HBsAg positive samples) revealed several mutations (V14A, F46S, N48T, L49R, I49T, D51G, A53V, P54L, Q82P, F83C, L127P, A184V, T189I, S204N, V224A), mostly outside the a-determinant. Several of these mutations are found as wild type nucleotides normally in genotype A and only exceptionally in genotype E. All three assays showed comparable sensitivities for genotype E HBsAg detection (98.4-100%) but differed considerably in specificity (84-99%). Failure to detect HBsAg antigen and differences in signal intensity were mainly associated with mutations in the preS/S gene outside the "a" determinant.