Detection of the hepatitis B surface antigen in patients with occult hepatitis B using an assay with enhanced sensitivity

Exchanges in the 'a' determinant of the hepatitis B virus surface antigen revisited

The hepatitis B virus surface antigen's (HBsAg) 'a' determinant comprises a sequence of amino acid residues located in the major hydrophilic region of the S protein, whose exchanges are closely associated with compromising the antigenicity and immunogenicity of that antigen. The HBsAg is generally present in the bloodstream of individuals with acute or chronic hepatitis B virus (HBV) infection. It is classically known as the HBV infection marker, and is therefore the first marker to be investigated in the laboratory in the clinical hypothesis of infection by this agent. One of the factors that compromises the HBsAg detection in the bloodstream by the assays adopted in serological screening in both clinical contexts is the loss of S protein antigenicity. This can occur due to mutations that emerge in the HBV genome regions that encode the S protein, especially for its immunodominant region - the 'a' determinant. These mutations can induce exchanges of amino acid residues in the S protein's primary structure, altering its tertiary structure and the antigenic conformation, which may not be recognized by anti-HBs antibodies, compromising the infection diagnosis. In addition, these exchanges can render ineffective the anti-HBs antibodies action acquired by vaccination, compromise the effectiveness of the chronically HBV infected patient's treatment, and also the HBsAg immunogenicity, by promoting its retention within the cell. In this review, the residues exchange that alter the S protein's structure is revisited, as well as the mechanisms that lead to the HBsAg antigenicity loss, and the clinical, laboratory and epidemiological consequences of this phenomenon.

HBV Biomarkers and Their Role in Guiding Treatment Decisions

Over 300 million individuals worldwide are chronically infected with hepatitis B virus and at risk for progressive liver disease. Due to the lack of a therapy that reliably achieves viral elimination and the variability of liver disease progression, treatment decisions are guided by the degree of liver disease and viral biomarkers as the viral life-cycle is well characterized and largely conserved between individuals. In contrast, the immunological landscape is much more heterogeneous and diverse and the measurement of its components is less well standardized. Due to the lack of a universal and easily measurable set of biomarkers, clinical practice guidelines remain controversial, aiming for a balance between simplifying treatment decisions by reducing biomarker requirements and using all available biomarkers to avoid overtreatment of patients with low risk for disease progression. While approved therapies such as nucleos(t)ide analogs improve patient outcomes, the inability to achieve a complete cure highlights the need for novel therapies. Since no treatment candidate has demonstrated universal efficacy, biomarkers will remain important for treatment stratification. Here, we summarize the current knowledge on virological and immunological biomarkers with a specific focus on how they might be beneficial in guiding treatment decisions in chronic hepatitis B.

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.

Performance evaluation of the MAGLUMI Hepatitis B virus surface antigen chemiluminescence immunoassay

A highly sensitive and reliable Hepatitis B virus surface antigen (HBsAg) measurement is essential to universal screening, timely diagnosis, and management of Hepatitis B virus (HBV) infection. This study aimed to evaluate the performance of MAGLUMI HBsAg chemiluminescence immunoassay (CLIA). MAGLUMI HBsAg (CLIA) was compared against ARCHITECT HBsAg. 411 HBsAg positive samples, including different stages of infection, genotypes, subtypes, mutants, and 30 seroconversion panels were tested to evaluate diagnostic sensitivity. Diagnostic specificity was evaluated by testing 205 hospitalized samples and 5101 blood donor samples. Precision, limit of blank (LoB), limit of detection (LoD), and linearity were also verified. The diagnostic sensitivity of the MAGLUMI HBsAg (CLIA) was 100% with better seroconversion sensitivity than ARCHITECT HBsAg. The MAGLUMI HBsAg (CLIA) has optimal detection efficacy for HBV subgenotypes samples. The analytical sensitivity is 0.039 IU/mL. The initial diagnostic specificity is 99.63% on blood donors and 96.59% on hospitalized samples. The verification data demonstrated high repeatability, a LoB of 0.02 IU/mL, LoD of 0.05 IU/mL and an excellent linearity of 0.050-250 IU/mL (R2 = 0.9946). The MAGLUMI HBsAg (CLIA) is proved a highly sensitive and reliable assay with optimal subgenotype detection efficacy.

Editorial: HBsAg seroclearance after pegylated interferon treatment-The beginning of the end

This article is linked to Gao et al papers. To view these articles, visit https://doi.org/10.1111/apt.17670 and https://doi.org/10.1111/apt.17710

Novel Assays to Solve the Clinical and Scientific Challenges of Chronic Hepatitis B

Chronic infection with Hepatitis B is a common, incurable, and deadly infection. Despite inexpensive laboratory tests for diagnosis and management that have been established for decades, the worldwide rate of diagnosis is only ∼10%, and ∼5% of people are under treatment. Novel assays have been developed to improve linkage to care by providing more flexible approaches to determine a patient's health status. Other assays have been established to better investigate intrahepatic host-virus interactions to support clinical trials for cure research. This review outlines the clinical and scientific challenges still to be solved and the upcoming methods used to address them.

ARCHITECT HBsAg Next assay is positioned better to resolve and refine challenging weak reactive clinical samples

BACKGROUND

Ultrasensitive HBsAg assays are replacing the previous versions. Unlike the sensitivity, the specificity, and its positioning to resolve weak-reactives (WR) are not studied. We investigated the ability of ARCHITECT HBsAg-Next (HBsAg-Nx) assay to resolve WR and sought its clinical validation and correlation with confirmatory/reflex testing.

METHODS

Among 99,761 samples between Jan 2022 - 2023, 248 reactive samples in HBsAg-Qual-II were compared with HBsAg-Nx assay. Sufficient samples were further subjected to neutralization (n = 108) and reflex (anti-HBc total/anti-HBs antibody) testing.

RESULTS

Out of 248 initial reactive samples in HBsAg-Qual-II, 180 (72.58%) were repeat reactive, and 68 (27.42%) were negative, whereas in HBsAg-Nx, 89 (35.89%) were reactive and 159 (64.11%) were negative (p<0.0001). Comparing the results of two assays (Qual-II/Next), 57.67% (n = 143) were concordant (++/-) and 105 (42.33%) were discordant (p = 0.0025). Testing of HBsAg-Qual-II + & HBsAg-Nx - samples revealed that 85.71% (n = 90) were anti-HBc total negative and 98.08% (n = 51) were not neutralized as well as significant proportion (89%) had no clinical correlation. The proportion of samples neutralized was significantly different between ≤5 S/Co (26.59%) and >5 S/Co (71.42%) (p = 0.0002). All samples (n = 26) with enhanced reactivity in HBsAg-Nx were effectively neutralized, while samples with no increase in reactivity, 89% (n = 72) failed neutralization (p=<0.001).

CONCLUSIONS

HBsAg-Nx assay is positioned better to resolve and refine challenging WR samples than Qual-II which correlated well with confirmatory/reflex tests and clinical disease. This superior internal benchmarking significantly reduced the cost and quantum of retesting, confirmatory/reflex testing in the diagnosis of HBV infection.

A longitudinal study to detect hepatitis B surface and core-related antigens in chronic hepatitis B patients with hepatitis B surface antigen seroclearance using highly sensitive assays

BACKGROUND

This study aimed to evaluate the usefulness of two novel assays, namely the iTACT-hepatitis B surface antigen (iTACT-HBsAg) and iTACT-hepatitis B core-related antigen (iTACT-HBcrAg) assays, in chronic hepatitis B (CHB) patients with HBsAg seroclearance (SC) documented by standard assays.

METHODS

HBsAg and HBcrAg were measured by the two iTACT-assays in 556 serial sera collected from 96 CHB patients at 7 different time points spanning from 5 years before to 10 years after SC and 120 HBsAg-negative, anti-HBc-positive individuals. As controls, 60 seronegative individuals, who were negative for HBsAg, anti-HBc and anti-HBs, were tested.

RESULTS

Using the iTACT-assays, HBsAg was detectable in 154/418 (36.8%) samples collected after SC. HBcrAg was detectable in 78.3% and 65.9% of samples collected before and after SC, respectively. The detectability rates of both HBsAg and HBcrAg progressively decreased over time after SC. At 10 years after SC, 20.4% and 64.5% of the patients still had detectable HBsAg and HBcrAg, respectively. 66 (71%) patients had detectable HBsAg and/or HBcrAg. Among the 120 HBsAg-negative, anti-HBc-positive individuals, 11 (9.2%) and 4 (3.3%) had detectable HBsAg and HBcrAg respectively. Both HBsAg and HBcrAg were undetectable in the controls.

CONCLUSION

The iTACT assays detected a low level of HBsAg and/or HBcrAg in >70% of patients even at 10 years after SC, suggesting that CHB patients with SC still harbour a low level of HBV protein expression. The clinical significance of detectable viral proteins after SC with regard to disease progression and HBV reactivation deserves further investigations.

Versatile performance edges of HBsAg Next assay in diagnosis and therapeutic monitoring of HBV infection

BACKGROUND

HBsAg Next assay (HBsAgNx) claims improved detection of HBsAg. The aim was to investigate its performance in ascertaining HBsAg loss, ability to detect HBsAg in various phases of HBV infection, specificity and its amenability to in-house neutralization.

METHODS

Analytical sensitivity was investigated using NIBSC standard (3rd WHO-IS). For clinical performance, out of 91,962 samples tested for HBsAg (Qual-II), 512 samples consisting of 170 cases with evidence of HBsAg loss during treatment (n = 116) and without treatment (n = 54), acute-hepatitis B (n = 90) and acute exacerbation of chronic-hepatitis B (n = 41), acute-hepatitis A (n = 24) and acute-hepatitis E (n = 9) positive, HIV-1 positive (n = 20), non-HBV, HAV and HEV related acute-hepatitis (n = 81) and HBsAg prozone (n = 14) as well as in-house neutralization (n = 63) were included.

RESULTS

The calculated limit of detection (LOD) was 0.004 IU/mL. Of the 170 patients with apparent HBsAg loss, 18/116 (15.5%) among treated and 15/54 (27.7%) with spontaneous clearance were positive in HBsAgNx (p < 0.0001). Additionally, it detected HBsAg in 12/95 (12.6%) and 6/34 (17.6%) patients who were HBV DNA negative in treatment experienced and spontaneous clearance groups respectively (p < 0.001). The specificity of HBsAgNx was comparable to HBsAg Qual-II. The signal-intensity of HBsAgNx was significantly higher than HBsAg Qual-II across various phases of HBV infection and prozone samples.

CONCLUSION

HBsAgNx significantly enhanced the accuracy of HBsAg detection without compromising the specificity in ascertaining HBsAg loss. The performance was superior in various phases of HBV infection including samples that exhibited prozone effect. Furthermore, it is amenable to cost-effective in-house neutralization to confirm low HBsAg levels.

An Ideal Hallmark Closest to Complete Cure of Chronic Hepatitis B Patients: High-sensitivity Quantitative HBsAg Loss

In the era of antiviral therapy, the main goal of treatment has shifted from the persistent inhibition of hepatitis B virus (HBV) replication to the pursuit of serological clearance of HBs surface antigen (HBsAg). Based on the life cycle of HBV, HBsAg originates from covalently closed circular DNA (cccDNA) and integrated HBV DNA, thus reflecting their transcriptional activity. Complete HBsAg loss may mean elimination or persistent inactivity of the HBV genome including cccDNA and integrated HBV DNA. HBsAg loss improves the recovery of abnormal immune function, which in turn, may further promote the clearance of residual viruses. Combined with functional cure and the great improvement of clinical outcomes, the continuous seroclearance of high-sensitivity quantitative HBsAg may represent the complete cure of chronic hepatitis B (CHB). For many other risk factors besides HBV itself, patients with HBsAg loss still need regular monitoring. In this review, we summarized the evolution of CHB treatment, the origin of serum HBsAg, the pattern of HBsAg seroclearance, and the effect of HBsAg loss on immune function and disease outcomes. In addition, we discuss the significance of high-sensitivity HBsAg detection and its possibility as a surrogate of complete cure.

Prevalence of occult hepatitis B virus infection in adults: a systematic review and meta-analysis

Background

Despite growing concerns about transmissibility and clinical impact, occult hepatitis B virus (HBV) infection has received little attention in the hepatitis elimination agenda. We aimed to estimate the prevalence of occult HBV infection at a global and regional scale and in specific populations.

Methods

For this systematic review and meta-analysis, we searched the MEDLINE, Embase, Global Health, and Web of Science databases for articles published in any language between Jan 1, 2010, and Aug 14, 2019. We included original articles and conference abstracts of any study design that reported the proportion of HBsAg-negative adults (aged ≥18 years) who are positive for HBV DNA (ie, people with occult HBV infection). The prevalence of occult HBV infection was pooled, using the DerSimonian-Laird random-effects model, in the general population and specific groups defined by the type of study participants (blood donors; other low-risk populations; high-risk populations; and people with advanced chronic liver disease), and stratified by HBV endemicity in each country. We also assessed the performance of anti-HBc as an alternative biomarker to detect occult HBV infection. The study was registered with PROSPERO, CRD42019115490.

Findings

305 of 3962 articles were eligible, allowing a meta-analysis of 140 521 993 individuals tested for HBV DNA. Overall, only two studies evaluated occult HBV infection in the general population, precluding unbiased global and regional estimates of occult HBV infection prevalence. In blood donors, occult HBV infection prevalence mirrored HBV endemicity: 0·06% (95% CI 0·00–0·26) in low-endemicity countries, 0·12% (0·04–0·23) in intermediate-endemicity countries, and 0·98% (0·44–1·72), in high-endemicity countries (p=0·0012). In high-risk groups, occult HBV infection prevalence was substantial, irrespective of endemicity: 5·5% (95% CI 2·9–8·7) in low-endemicity countries, 5·2% (2·5–8·6) in intermediate-endemicity countries, and 12·0% (3·4–24·7) in high-endemicity countries. The pooled sensitivity of anti-HBc to identify occult HBV infection was 77% (95% CI 62–88) and its specificity was 76% (68–83).

Interpretation

A substantial proportion of people carry occult HBV infection, especially among high-risk groups across the globe and people living in highly endemic countries. Occult HBV infection should be part of the global viral hepatitis elimination strategy.

Funding

None.