Variable capacity of 13 hepatitis B virus surface antigen assays for the detection of HBsAg mutants in blood samples

Proteoforms and their expanding role in laboratory medicine

The term “proteoforms” describes the range of different structures of a protein product of a single gene, including variations in amino acid sequence and post-translational modifications. This diversity in protein structure contributes to the biological complexity observed in living organisms. As the concentration of a particular proteoform may increase or decrease in abnormal physiological states, proteoforms have long been used in medicine as biomarkers of health and disease. Notably, the analytical approaches used to analyze proteoforms have evolved considerably over the years. While ligand binding methods continue to play a large role in proteoform measurement in the clinical laboratory, unanticipated or unknown post-translational modifications and sequence variants can upend even extensively tested and vetted assays that have successfully made it through the medical regulatory process. As an alternate approach, mass spectrometry—with its high molecular selectivity—has become an essential tool in detection, characterization, and quantification of proteoforms in biological fluids and tissues. This review explores the analytical techniques used for proteoform detection and quantification, with an emphasis on mass spectrometry and its various applications in clinical research and patient care including, revealing new biomarker targets, helping improve the design of contemporary ligand binding in vitro diagnostics, and as mass spectrometric laboratory developed tests used in routine patient care.

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

Patients with occult hepatitis B infection (OBI) have undetectable hepatitis B surface antigen (HBsAg) by conventional assays but detectable hepatitis B virus (HBV) DNA in blood/liver. We evaluated the key performance characteristics of a sensitive HBsAg assay (ARCHITECT HBsAg Next Qualitative Assay, referred as NEXT) with respect to HBsAg detection. Assay precision, sample carryover and seroconversion sensitivity of NEXT were evaluated. HBsAg was measured by NEXT in 1,138 individuals, including 1,038 patients who attended liver clinics in a tertiary hospital (200 HBV DNA-positive blood donors whose HBsAg was undetectable by conventional assays, and 38 patients receiving immunosuppressive therapy, 800 chronic hepatitis B patients with HBsAg seroclearance) and 100 HBsAg-negative subjects recruited from a community project. The within-run and within-laboratory coefficients of variation were <6% for the positive sample pools. In 9 seroconversion panels tested, NEXT allowed an earlier HBsAg detection than conventional assays. NEXT detected HBsAg in 10/200 (5%) HBsAg-negative blood donors, 1/20 (5%) and 0/18 HBsAg-negative patients with and without HBV reactivation respectively, and 59/800 (7.3%) patients with HBsAg seroclearance. HBsAg was detectable by NEXT in 27.8%, 8.2%, 6.9%, 3.8% and 1.9% samples at <3, 3-5, >5-8, >8-11, and >11 years after HBsAg seroclearance, respectively. Seven out of 100 HBsAg-negative community identified subjects was tested positive by NEXT. Comparing with conventional HBsAg assays, NEXT demonstrated a higher sensitivity and conferred an increment of 5-7% detection rate in patients with OBI, thereby helping in identifying HBV carriers and prevention of OBI-associated HBV transmission and reactivation.

Detection of the serological markers hepatitis B virus surface antigen (HBsAg) and hepatitis B core IgM antibody (anti-HBcIgM) in the diagnosis of acute hepatitis B virus infection after recent exposure

The serological diagnosis of acute hepatitis B virus (HBV) infection after recent exposure has been established by the hepatitis B virus surface antigen (HBsAg) and anti-hepatitis B core IgM antibody (anti-HBcIgM) detection in serum, sometimes accompanied by the detection of hepatitis B "e" antigen (HBeAg). Despite this characteristic serological profile, misdiagnosis can occur in cases of unexpected or atypical behavior of the serological markers in the bloodstream, or if the true meaning of its expression is not properly investigated, or even if there is a possibility of interference from factors not necessarily linked to the infectious process, in the detection of these markers. This review discusses the influence of these variables on laboratory results for these two serological markers and, therefore, the potential risk of these variables compromising the correct diagnosis of acute infection after recent HBV exposure.

Kidney transplant from donors with hepatitis B: A challenging treatment option

Utilizing kidneys from donors with hepatitis B is one way to alleviate the current organ shortage situation. However, the risk of hepatitis B virus (HBV) transmission remains a challenge that undermines the chance of organs being used. This is particularly true with hepatitis B surface antigen (HBsAg) positive donors despite the comparable long-term outcomes when compared with standard donors. To reduce the risk of HBV transmission, a comprehensive approach is needed. This includes assessment of donor risk, optimal allocation to the proper recipient, appropriate immunosuppressive regimen, optimizing the prophylactic therapy, and post-transplant monitoring. This review provides an overview of current evidence of kidney transplants from donors with HBsAg positivity and outlines the challenge of this treatment. The topics include donor risk assessment by adopting the nucleic acid test coupled with HBV DNA as the HBV screening, optimal recipient selection, importance of hepatitis B immunity, role of nucleos(t)ide analogues, and hepatitis B immunoglobulin. A summary of reported long-term outcomes after kidney transplantation and proposed criteria to utilize kidneys from this group of donors was also defined and discussed.

Functional Cure of Hepatitis B Virus Infection in Individuals With HIV-Coinfection: A Literature Review

In individuals infected with hepatitis B virus (HBV), the loss of hepatitis B surface antigen (HBsAg) is the ultimate therapeutic goal, which defines "functional cure." For individuals living with human immunodeficiency virus (HIV), functional cure occurs roughly 2 per 100 person-years during potent anti-HBV containing antiretroviral therapy. Although this rate may be higher than expected in treated HBV mono-infected individuals, rates of functional cure widely vary between studies (0.6-10.5 per 100 person-years). Similar to HBV mono-infection, the phase of HBV infection, HBV (sub-)genotypes and hepatitis B "e" Ag-negative variants are associated with functional cure in treated HIV-HBV co-infection. In specifically HIV-HBV co-infected individuals, strong increases in CD4+ T cell counts after treatment initiation have also been linked to functional cure, yet this finding is inconsistent across studies. Several markers directly or indirectly reflecting HBV activity are being developed to predict functional cure, such as quantification of HBsAg, hepatitis B core-related antigen, HBsAg protein composition, anti-hepatitis B core antibodies and interferon-gamma-inducible protein 10. Few have been assessed during treatment in HIV-HBV co-infected individuals and none have been validated to predict functional cure. Novel therapeutics for HBV cure are essential for individuals with HIV-HBV co-infection and need to be separately evaluated in this population.

Evolutionary Analysis of Pre-S/S Mutations in HBeAg-Negative Chronic Hepatitis B With HBsAg < 100 IU/ml

Background: Hepatitis B surface antigen (HBsAg) and viral load are important clinical indicators for antiviral therapy. Few studies have evaluated viral sequence biomarkers predicting the risk of hepatocellular carcinoma (HCC) in the stage, which show a low serological response (HBsAg < 100 IU/ml) and high viral levels (HBV DNA > 2,000 IU/ml). This study aims to determine the trend of the biological prevalence within the pre-S/S regions of special model of inactive CHB infection. Methods: We used Sanger sequencing, quantitative HBV serology (HBeAg and HBsAg), and liver function index to identify whether HBV genome sequences are associated with long-term risk of further HCC progression in special inactive CHB infection. Results: HBV sequencing analysis of 28 CHB patients with special infectious pattern showed higher genetic diversity among four opening reading frames (ORFs) (p < 0.001). However, dN/dS ratios of HBsAg and pre-C/C regions in the experimental group showed no significantly different from those in the HCC group (p = 0.06), while significantly lower in polymerase and HBxAg regions of the experimental group (p < 0.001). In addition, seven positively selected sites were identified in pre-S1, five in pre-S2, and four in S, in which five sites (128H/135Q/135R/139L/141P) were among "α" determinant. Conclusions: These mutations in the pre-S/S region might be associated with the HCC phenotype of low HBsAg expression, with the P region possibly impacting high viral loads. Increased viral diversity across the HBV genome is also associated with low levels of HBsAg. The cumulative evolutionary changes in the HBV pre-S/S regions shows that facilitate immune evasion should be monitored individually. Due to the similarity of evolutionary characteristics in HCC, low serological responses and high viremia may be associated with the risk of further disease progression.

An automated clinical mass spectrometric method for identification and quantification of variant and wild-type amyloid-β 1-40 and 1-42 peptides in CSF

INTRODUCTION

We developed an automated liquid chromatography-tandem mass spectrometry high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method for multiplex quantification of wild-type (wt) amyloid β (Aβ) peptides 1-40 (Aβ40) and 1-42 (Aβ42) and detection of variant Aβ peptides in cerebrospinal fluid.

METHODS

The multiplex Aβ HPLC-MS/MS assay was validated in a clinically accredited laboratory following regulatory guidelines, with Aβ42 calibration assigned to the ERM/IFCC certified reference material; sequence variants were additionally multiplexed into the method.

RESULTS

Sample preparation was fully automated on a liquid handler. The assay quantified wt-Aβ42 and wt-Aβ40 and detected sequence variants, when present, within the Aβ42 sequence.

DISCUSSION

Extension of the HPLC-MS/MS approach for quantification of wt-Aβ42 and wt-Aβ40 to include known sequence variants increases analytical accuracy of the mass spectrometric approach and enables identification of cases of autosomal dominant Alzheimer's disease. Development of an automated workflow and selection of appropriate instrumentation enabled deployment of this method in routine clinical testing.

Comprehensive analysis of hepatitis B virus infections in blood donors in southern China that are surface antigen positive but nucleic acid testing negative

BACKGROUND

Hepatitis B virus (HBV) infection is one of the major concerns for the safety of blood transfusion in high-prevalent countries such as in China. Prior studies outside of China have shown hepatitis B surface antigen (HBsAg) false-reactive rate of 0.02% to 0.04%. Similarly, false-negative HBsAg and HBV DNA results may occur in infected donors. Our study analyzed HBsAg enzyme-linked immunosorbent assay (ELISA)-reactive but NAT-negative donations in Shenzhen Blood Center, China.

STUDY DESIGN AND METHODS

HBsAg ELISA-positive/NAT-negative plasma samples identified from screening 101,025 donations during 2017-2018 were analyzed by molecular and serologic tests including neutralization, chemiluminescence immunoassays, and various HBV DNA amplification assays. Molecular characterizations of HBsAg-positive/NAT-negative samples were determined by quantitative polymerase chain reaction (qPCR) and nested PCR amplification of the basic core and precore promotor regions (295 base pairs) and HBsAg (S) region (496 base pairs).

RESULTS

Screening of 101,025 eligible blood donations identified 157 (0.16%, 95% confidence interval, 0.13%-0.18%) HBsAg ELISA-positive/NAT-negative plasma samples; of those, 71 (45.2%) were HBsAg confirmed positive by further HBsAg testing and DNA positive by molecular tests with increased sensitivity. Of the 71, all but one was antibody to hepatitis B core antigen reactive without antibody to hepatitis B surface antigen, yielding one recent (window-period) HBV infection. Of the remaining donations, 80 (51%) were not considered as HBV-infected donors, and 6 (3.8%) were interpreted as indeterminate since HBsAg results were discordant with unconfirmed HBV DNA results. In the 71 confirmed positives, HBsAg levels ranged from 0.05 to 400 IU/mL and HBV DNA from 6 to 2654 IU/mL; however, the correlation between the two was weak (R² = 0.24).

CONCLUSION

Fewer than half of HBsAg ELISA-positive/NAT-negative samples were confirmed as HBsAg positive. Our study demonstrates that in highly HBV-endemic countries, assays with high sensitivity and specificity may be required.

Hepatitis B Virus Mutant Infections in Hemodialysis Patients: A Case Series

Rationale & Objective

Hepatitis B virus (HBV) transmission in hemodialysis units has become a rare event since implementation of hemodialysis-specific infection control guidelines: performing hemodialysis for hepatitis B surface antigen (HBsAg)-positive patients in an HBV isolation room, vaccinating HBV-susceptible (HBV surface antibody and HBsAg negative) patients, and monthly HBsAg testing in HBV-susceptible patients. Mutations in HBsAg can result in false-negative HBsAg results, leading to failure to identify HBsAg seroconversion from negative to positive. We describe 4 unique cases of HBsAg seroconversion caused by mutant HBV infection or reactivation in hemodialysis patients.

Study Design

Following identification of a possible HBsAg seroconversion and mutant HBV infection, public health investigations were launched to conduct further HBV testing of case patients and potentially exposed patients. A case patient was defined as a hemodialysis patient with suspected mutant HBV infection because of false-negative HBsAg testing results. Confirmed case patients had HBV DNA sequences demonstrating S-gene mutations.

Setting & Participants

Case patients and patients potentially exposed to the case patient in the respective hemodialysis units in multiple US states.

Results

4 cases of mutant HBV infection in hemodialysis patients were identified; 3 cases were confirmed using molecular sequencing. Failure of some HBsAg testing platforms to detect HBV mutations led to delays in applying HBV isolation procedures. Testing of potentially exposed patients did not identify secondary transmissions.

Limitations

Lack of access to information on past HBsAg testing platforms and results led to challenges in ascertaining when HBsAg seroconversion occurred and identifying and testing all potentially exposed patients.

Conclusions

Mutant HBV infections should be suspected in patients who test HBsAg negative and concurrently test positive for HBV DNA at high levels. Dialysis providers should consider using HBsAg assays that can also detect mutant HBV strains for routine HBV testing.

Variants of hepatitis B virus surface antigen observed during therapy with nucleic acid polymer REP 2139-Ca have no influence on treatment outcome and its detection by diagnostic assays

The treatment of patients suffering from HBeAg-positive chronic hepatitis B with REP 2139-Ca resulted in potent reductions in HBsAg and HBV DNA, seroconversion to anti-HBs and the establishment of functional control of infection. In this cohort of 12 patients, we investigated whether differences between HBsAg sequences might explain the lack of response to REP 2139-Ca observed in 3 of 12 patients. We also assessed if the reduction or complete loss of HBsAg in serum observed during therapy were caused by mutations in the "a" determinant preventing the detection of HBsAg by standard diagnostic assays. The complete pre-S/S open reading frame (ORF) was sequenced and pre-S1, pre-S2 and S amino acid sequences were analysed. We found no major differences between pre-S1, pre-S2 and S sequences in responders and nonresponders correlated with low reduction in HBsAg. In addition, we found no mutations in the "a" determinant that would significantly affect the reactivity of HBsAg in diagnostic assays. These results demonstrate that the amino acid sequence of complete pre-S/S ORF has no direct influence on response to REP 2139-Ca therapy.

Effect of hepatitis B virus (HBV) surface-gene variability on markers of replication during treated human immunodeficiency virus-HBV infection in Western Africa

BACKGROUND & AIMS

Replication markers exhibit substantial variation during chronic hepatitis B virus (HBV) infection, part of which can be explained by mutations on the surface (S) gene. We aimed to identify S-gene mutations possibly influencing the quantification of HBV replication markers (MUPIQH) in HBV genotype E infection, common to Western Africa.

METHODS

Seventy-three antiretroviral treatment (ART)-naïve human immunodeficiency virus (HIV)-HBV co-infected patients from Côte d'Ivoire, initiating anti-HBV-containing ART, had available HBV S-gene sequences. S-gene MUPIQHs were screened at ART initiation based on lower HBV-DNA or HBsAg quantification (qHBsAg) compared to wildtype. Their association with HBV virological response and qHBsAg slope during treatment was evaluated.

RESULTS

Genotype E was predominant (95.9%). At ART initiation, median HBV-DNA was 7.27 log₁₀ copies/mL (IQR = 5.26-8.33) and qHBsAg 4.08 log₁₀ IU/mL (IQR = 3.49-4.61). Twelve S-gene MUPIQHs were identified among 21 patients (28.8%): sS140L (n = 4), sD144A (n = 1), sS167L (n = 2), sS174N (n = 6), sP178Q (n = 2), sG185L (n = 2), sW191L (n = 2), sP203Q/R (n = 2), sS204N/I/R/K/T/G (n = 7), sN207T (n = 2), sF212C (n = 1) and sV224A/Y (n = 7). MUPIQHs at positions s185+s191+s224 and s178+s204 were within highly covarying networks of S-gene mutations. Older age (P = 0.02), elevated transaminases (P = 0.03) and anti-hepatitis B "e" antibody-positive serology (P = 0.009) were significantly associated with prevalent MUPIQHs at ART initiation. During treatment, baseline MUPIQHs were not associated with time-to-undetectable HBV-DNA (P = 0.7) and qHBsAg levels decreased at similar rates between those with vs without MUPIQHs (P = 0.5).

CONCLUSION

Several novel S-gene mutations were associated with reductions in replication markers among West African co-infected patients. These mutations, however, do not affect response during antiviral treatment. Their diagnostic and clinical consequences need clarification.

Detection of in vivo hepatitis B virus surface antigen mutations-A comparison of four routine screening assays

An important requirement for a state-of-the-art hepatitis B surface antigen (HBsAg) screening assay is reliable detection of mutated HBsAg. Currently, there is a striking shortage of data regarding the detection rates of in vivo HBsAg mutations for these clinically important assays. Therefore, we compared the detection rates of four commercial HBsAg screening assays using a global cohort of 1553 patients from four continents with known HBV genotypes. These samples, which represent the broadest spectrum of known and novel HBsAg major hydrophilic region (MHR) mutations to date, were analyzed for the presence of HBsAg using the Roche Elecsys^® HBsAg II Qualitative, Siemens ADVIA Centaur XP HBsAg II, Abbott Architect HBsAg Qualitative II and DiaSorin Liaison^® HBsAg Qualitative assays, respectively. Of the 1553 samples, 1391 samples could be sequenced; of these, 1013 (72.8%) carried at least one of the 345 currently known amino acid substitutions (distinct HBsAg mutation) in the HBsAg MHR. All 1553 patient samples were positive for HBsAg using the Elecsys^® HBsAg II Qual assay, with a sensitivity (95% confidence interval) of 99.94% (99.64%-100%), followed by the Abbott Architect 99.81% (99.44%-99.96%), Siemens ADVIA 99.81% (99.44%-99.96%) and DiaSorin Liaison^® 99.36% (98.82%-99.69%) assays, respectively. Our results indicate that the Elecsys^® HBsAg II Qual assay exhibits the highest sensitivity among the commercial HBsAg screening assays, and demonstrate that its capacity to detect HBV infection is not compromised by HBsAg MHR mutants.

An ultra-sensitive Abbott ARCHITECT® assay for the detection of hepatitis B virus surface antigen (HBsAg)

BACKGROUND

Critical to the identification of HBV infection and the prevention of transfusion transmitted disease is the sensitive and accurate detection of Hepatitis B virus surface antigen (HBsAg). Improvements in HBsAg assay sensitivity approaching the performance of nucleic acid testing (NAT) are essential to further reduce the detection window for acute HBV infection in regions where NAT is not widely available.

OBJECTIVES AND STUDY DESIGN

An improved HBsAg assay on the fully-automated Abbott ARCHITECT^® platform was developed to improve sensitivity, mutant and genotype detection.

RESULTS

The analytical sensitivity of the improved prototype assay is 5.2 mIU/ml, which is 3.86- to 14.54-fold more sensitive than comparator assays based on the WHO International Reference Standard. The enhanced sensitivity was also demonstrated with 27 HBV seroconversion panels, detecting more panel members (191 of 364) vs. the ARCHITECT^® Qual I (144), Qual II (160) and PRISM^® (148) HBsAg assays. Further, the assay detected 7 of 12 HBV DNA positive/HBsAg negative samples, and detected all evaluated mutants and genotypes with higher sensitivity than the comparator assays. The improvement in sensitivity did not diminish assay specificity, attaining 100% (95% CI, 99.97-100%) on 10,633 blood donors.

CONCLUSIONS

An Abbott ARCHITECT^® HBsAg assay with clinical performance approaching that of mini-pool NAT (approximately 100 copies/ml was developed. The assay has superior HBsAg mutant and genotype detection and specificity, all of which are important for the diagnosis and management of HBV infection.

Reactivation of a Vaccine Escape Hepatitis B Virus Mutant in a Cambodian Patient During Anti-Hepatitis C Virus Therapy

A 76-year-old Cambodian man co-infected with hepatitis B virus (HBV) and hepatitis C virus (HCV) 6c-1 presented for care. HBV DNA was intermittently detectable despite anti-HBs levels being above the protective threshold. During treatment for HCV, HBV DNA levels increased. Sequencing revealed multiple mutations including vaccine escape mutation and mutations predicted to enhance fitness. This case represents exacerbation of an HBV vaccine escape mutant during a direct-acting antiviral therapy.

Frequency of hepatitis B surface antigen variants (HBsAg) in hepatitis B virus genotype B and C infected East- and Southeast Asian patients: Detection by the Elecsys® HBsAg II assay

BACKGROUND

To avoid false negative results, hepatitis B surface antigen (HBsAg) assays need to detect samples with mutations in the immunodominant 'a' determinant region, which vary by ethnographic region.

OBJECTIVE

We evaluated the prevalence and type of HBsAg mutations in a hepatitis B virus (HBV)-infected East- and Southeast Asian population, and the diagnostic performance of the Elecsys^® HBsAg II Qualitative assay.

STUDY DESIGN

We analyzed 898 samples from patients with HBV infection from four sites (China [Beijing and Guangzhou], Korea and Vietnam). HBsAg mutations were detected and sequenced using highly sensitive ultra-deep sequencing and compared between the first (amino acids 124-137) and second (amino acids 139-147) loops of the 'a' determinant region using the Elecsys^® HBsAg II Qualitative assay.

RESULTS

Overall, 237 distinct amino acid mutations in the major hydrophilic region were identified; mutations were present in 660 of 898 HBV-infected patient samples (73.5%). Within the pool of 237 distinct mutations, the majority of the amino acid mutations were found in HBV genotype C (64.8%). We identified 25 previously unknown distinct mutations, mostly prevalent in genotype C-infected Korean patients (n = 18) followed by Chinese (n = 12) patients. All 898 samples were correctly identified by the Elecsys^® HBsAg II Qualitative assay.

CONCLUSIONS

We observed 237 distinct (including 25 novel) mutations, demonstrating the complexity of HBsAg variants in HBV-infected East- and Southeast Asian patients. The Elecsys^® HBsAg II Qualitative assay can reliably detect HBV-positive samples and is suitable for routine diagnostic use in East and Southeast Asia.

Hepatitis B Virus Blood Screening: Need for Reappraisal of Blood Safety Measures?

Over the past decades, the risk of HBV transfusion–transmission has been steadily reduced through the recruitment of volunteer donors, the selection of donors based on risk-behavior evaluation, the development of increasingly more sensitive hepatitis B antigen (HBsAg) assays, the use of hepatitis B core antibody (anti-HBc) screening in some low-endemic countries, and the recent implementation of HBV nucleic acid testing (NAT). Despite this accumulation of blood safety measures, the desirable zero risk goal has yet to be achieved. The residual risk of HBV transfusion–transmission appears associated with the preseroconversion window period and occult HBV infection characterized by the absence of detectable HBsAg and extremely low levels of HBV DNA. Infected donations tested false-negative with serology and/or NAT still persist and derived blood components were shown to transmit the virus, although rarely. Questions regarding the apparent redundancy of some safety measures prompted debates on how to reduce the cost of HBV blood screening. In particular, accumulating data strongly suggests that HBsAg testing may add little, if any HBV risk reduction value when HBV NAT and anti-HBc screening also apply. Absence or minimal acceptable infectious risk needs to be assessed before considering discontinuing HBsAg. Nevertheless, HBsAg remains essential in high-endemic settings where anti-HBc testing cannot be implemented without compromising blood availability. HBV screening strategy should be decided according to local epidemiology, estimate of the infectious risk, and resources.

Prediction value of serum HBV large surface protein in different phases of HBV infection and virological response of chronic hepatitis B patients

BACKGROUND

Serum HBV large surface protein (HBV-LP) is an envelope protein that has a close relationship with HBV DNA level. This study is to explore the prediction value of HBV-LP in different phase of HBV infection and during antiviral therapy in chronic hepatitis B (CHB) patients.

METHODS

A retrospective study was conducted in 2033 individuals, which included 1677 HBV infected patients in different phases and 356 healthy controls. HBV-LP, HBV serum markers and HBV DNA were detected by ELISA, CMIA and qRT-PCR, respectively. 85 CHB patients receiving PegIFNα or ETV were divided into virological response (VR) and partial virological response (PVR). The dynamic changes of HBV DNA and HBV-LP were observed.

RESULTS

The level of HBV-LP in 2033 individuals was shown as: HBeAg-positive hepatitis > HBeAg-positive infection > HBeAg-negative hepatitis > HBeAg-negative infection > healthy controls. HBV-LP was positive in all patients whose HBV DNA > 1.0E + 06 IU/ml. When HBsAg was <0.05 IU/ml or >1000 IU/ml, HBV DNAs were all negative if HBV-LP < 1.0 S/CO. When HBsAg was between 0.05 IU/ml and 1000 IU/ml, the consistency of HBV-LP with HBV DNA was 100% in case of HBV-LP > 4.0 S/CO in HBeAg-positive patients and HBV-LP > 2.0 S/CO in HBeAg-negative ones. During antiviral therapy, baseline HBV-LP was lower in VR patients than that in PVR patients. The optimal cut-off points to predict VR by baseline HBV-LP were 32.4 and 28.6 S/CO for HBeAg-positive and HBeAg-negative hepatitis patients, respectively.

CONCLUSIONS

HBV-LP may be a useful marker for distinguishing the different phases of HBV infection. Moreover, baseline HBV-LP level can be used for predicting VR of CHB patients.

Diagnostic accuracy of tests to detect hepatitis B surface antigen: a systematic review of the literature and meta-analysis

BACKGROUND

Chronic Hepatitis B Virus (HBV) infection is characterised by the persistence of hepatitis B surface antigen (HBsAg). Expanding HBV diagnosis and treatment programmes into low resource settings will require high quality but inexpensive rapid diagnostic tests (RDTs) in addition to laboratory-based enzyme immunoassays (EIAs) to detect HBsAg. The purpose of this review is to assess the clinical accuracy of available diagnostic tests to detect HBsAg to inform recommendations on testing strategies in 2017 WHO hepatitis testing guidelines.

METHODS

The systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines using 9 databases. Two reviewers independently extracted data according to a pre-specified plan and evaluated study quality. Meta-analysis was performed. HBsAg diagnostic accuracy of rapid diagnostic tests (RDTs) was compared to enzyme immunoassay (EIA) and nucleic-acid test (NAT) reference standards. Subanalyses were performed to determine accuracy among brands, HIV-status and specimen type.

RESULTS

Of the 40 studies that met the inclusion criteria, 33 compared RDTs and/or EIAs against EIAs and 7 against NATs as reference standards. Thirty studies assessed diagnostic accuracy of 33 brands of RDTs in 23,716 individuals from 23 countries using EIA as the reference standard. The pooled sensitivity and specificity were 90.0% (95% CI: 89.1, 90.8) and 99.5% (95% CI: 99.4, 99.5) respectively, but accuracy varied widely among brands. Accuracy did not differ significantly whether serum, plasma, venous or capillary whole blood was used. Pooled sensitivity of RDTs in 5 studies of HIV-positive persons was lower at 72.3% (95% CI: 67.9, 76.4) compared to that in HIV-negative persons, but specificity remained high. Five studies evaluated 8 EIAs against a chemiluminescence immunoassay reference standard with a pooled sensitivity and specificity of 88.9% (95% CI: 87.0, 90.6) and 98.4% (95% CI: 97.8, 98.8), respectively. Accuracy of both RDTs and EIAs using a NAT reference were generally lower, especially amongst HIV-positive cohorts.

CONCLUSIONS

HBsAg RDTs have good sensitivity and excellent specificity compared to laboratory immunoassays as a reference standard. Sensitivity of HBsAg RDTs may be lower in HIV infected individuals.

HBV genotypes and drug resistance mutations in antiretroviral treatment-naive and treatment-experienced HBV-HIV-coinfected patients

BACKGROUND

The presence of HBV resistance mutations upon initiation or during antiretroviral therapy (ART) in HIV-coinfected patients is an important determinant of treatment response. The main objective of the study was to determine the prevalence of HBV resistance mutations in antiretroviral treatment-naive and treatment-experienced HBV-HIV-coinfected Ghanaian patients with detectable HBV viraemia.

METHODS

HBV-HIV-coinfected patients who were ART-naive or had received at least 9 months of lamivudine (3TC)-containing ART were enrolled in a cross-sectional study. Demographic and clinical data were collected and HBV DNA quantified. Partial HBV sequences were amplified by PCR and sequenced bi-directionally to obtain a 2.1-2.2 kb fragment for phylogenetic analysis of HBV genotypes and evaluation of drug resistance mutations.

RESULTS

Of the 100 HBV-HIV-coinfected study patients, 75 were successfully PCR-amplified, and 63 were successfully sequenced. Of these 63 patients, 27 (42.9%) were ART-experienced and 58 (92.1%) had HBV genotype E. No resistance mutations were observed in the 36 ART-naive patients, while 21 (77.8%) of 27 treatment-experienced patients had resistance mutations. All patients with resistance mutations had no tenofovir in their regimens, and 80% of them had HIV RNA <40 copies/ml. The 3TC resistance mutations rtL180M and rtM204V were observed in 10 (47.6%) of the 21 patients, while 5 patients (23.8%) had rtV173L, rtL180M and rtM204V mutations.

CONCLUSIONS

A high proportion of HBV-HIV-coinfected patients with detectable viraemia on 3TC-containing ART had resistance mutations despite good ART adherence as determined by HIV RNA suppression. This study emphasizes the need for dual therapy as part of a fully suppressive ART in all HBV-HIV-coinfected patients in Ghana.

Occult hepatitis B virus infection: influence of S protein variants

Background

In occult hepatitis B viral infection (OBI), the persistence of hepatitis B virus (HBV) DNA is associated with a lack of hepatitis B surface antigen (HBsAg). To assess the possible role of HBsAg immune escape variants in OBI patients, variability in the HBV S gene was evaluated for OBI patients as well as chronic HBV infection patients from the same families.

Methods

We selected 17 HBV DNA-positive/HBsAg-negative patients (OBI group) and 15 HBV DNA- and HBsAg-positive patients from OBI families (control group). The S gene was amplified and cloned, and at least 15 clones per patient were sequenced and analyzed.

Results

Although the incidence of stop codon mutations within the S region was higher in the OBI group (13.6 %) than in the control group (1.5 %, P < 0.001), this type of mutation, together with insertion and deletion mutations, was prevalent in only three OBI patients. In the major hydrophilic region (MHR), a median of 0.75 residues were altered in every 100 residues for the OBI patients, whereas 0.95 out of 100 residues were changed in the control group (P = 0.428). Furthermore, some variants that are generally considered immune escape variants, such as mutations at positions s145, s147, and s123, were only observed in less than 5 % of all the clones sequenced, in either OBI or control group.

Conclusions

Our data suggest that HBsAg variants may not play a major role in OBI pathogenesis.

Broad Range of Hepatitis B Virus (HBV) Patterns, Dual Circulation of Quasi-Subgenotype A3 and HBV/E and Heterogeneous HBV Mutations in HIV-Positive Patients in Gabon

Integrated data on hepatitis B virus (HBV) patterns, HBV genotypes and mutations are lacking in human immunodeficiency virus type 1 (HIV-1) co-infected patients from Africa. This survey was conducted in 2010-2013 among 762 HIV-1-positive adults from Gabon who were predominantly treated with 3TC-based antiretroviral treatment. HBV patterns were identified using immunoassays detecting total antibody to hepatitis B core antigen (HBcAb), hepatitis B surface antigen (HBsAg), IgM HBcAb, hepatitis B e antigen (HBeAg), antibody to HBsAg (HBsAb) and an in-house real-time PCR test for HBV DNA quantification. Occult hepatitis B (OBI) was defined by the presence of isolated anti-HBc with detectable serum HBV DNA. HBV genotypes and HBV mutations were analyzed by PCR-direct sequencing method. Seventy-one (9.3%) patients tested positive for HBsAg, including one with acute hepatitis B (0.1%; 95% CI, 0.0%-0.2%), nine with HBeAg-positive chronic hepatitis B (CHB) (1.2%; 95% CI, 0.6%-2.2%), 16 with HBeAg-negative CHB (2.1%; 95% CI, 1.2%-3.3%) and 45 inactive HBV carriers (5.9%; 95% CI, 4.4%-7.8%). Sixty-one (8.0%; 95% CI, 6.2%-10.1%) patients showed OBI. Treated patients showed similar HBV DNA levels to those obtained in untreated patients, regardless of HBV patterns. Around 15.0% of OBI patients showed high (>1,000 UI/mL) viremia. The mutation M204V/I conferring resistance to 3TC was more common in HBV/A (47.4%) than in HBV/E isolates (0%) (P = .04). Our findings encouraged clinicians to promote HBV vaccination in patients with no exposure to HBV and to switch 3TC to universal TDF in those with CHB.

Clinical significance of hepatitis B surface antigen mutants

Hepatitis B virus (HBV) infection is a major public health problem in many countries, with nearly 300 million people worldwide carrying HBV chronic infection and over 1 million deaths per year due to cirrhosis and liver cancer. Several hepatitis B surface antigen (HBsAg) mutations have been described, most frequently due to a single amino acid substitution and seldom to a nucleotide deletion. The majority of mutations are located in the S region, but they have also been found in the pre-S1 and pre-S2 regions. Single amino acid substitutions in the major hydrophilic region of HBsAg, called the “a” determinant, have been associated with immune escape and the consequent failure of HBV vaccination and HBsAg detection, whereas deletions in the pre-S1 or pre-S2 regions have been associated with the development of hepatocellular carcinoma. This review article will focus on the HBsAg mutants and their biological and clinical implications.

Identifying patients infected with hepatitis B virus in sub-Saharan Africa: potential for misclassification

Most research in sub-Saharan Africa establishes hepatitis B infection via one-time hepatitis B surface antigen (HBsAg) testing. Of 237 HIV-infected patients from two clinical trials testing HBsAg positive (MiniVidas®), 206 (86.9%) had validated serological tests using another assay (Architect). Discrepancies could be due to inactive infection, highlighting the importance of assessing hepatitis B virus infection phase.

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

BACKGROUND

Presence at the same time of HBsAg and anti-HBs antibodies (HBsAg/Ab) is an entity sometimes encountered in chronic hepatitis B (CHB) carriers.

OBJECTIVES

This 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 DESIGN

Among 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.

RESULTS

HBsAg 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 (R(2): 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.

CONCLUSIONS

The 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.

[Diagnosis of chronic hepatitis B infection]

BACKGROUND

Infection with the hepatitis B virus can lead to chronic liver inflammation with the risk of developing cirrhosis and cancer of the liver. Increased knowledge and improved treatment of chronic hepatitis B infection in recent years mean that virological tests are increasingly used to ascertain the course of illness, status and response to treatment by the individual patient. The purpose is therefore to provide an updated overview of available diagnostics.

METHOD

The article builds on a selection of original and review articles identified through a search in Medline, as well as experience of microbiological diagnostics from the national reference laboratory for the hepatitis virus in Norway.

RESULTS

Detection of virus proteins and antibodies to these, as well as virus quantification and characterisation, form an important part of the assessment of hepatitis B infection, including confirmation of the chronic phase of the illness.

INTERPRETATION

Proper diagnosis is based on a broad selection of different serological and virological markers. Genotype and certain mutations may affect the course of illness and the response to treatment. To prevent further transmission and offer effective treatment, it is important to identify chronic carriers, but also persons who have previously been infected with hepatitis B virus with risk of reactivation.

Performance of hepatitis B surface antigen tests with the first WHO international hepatitis B virus genotype reference panel

BACKGROUND

Standardization of hepatitis B surface antigen (HBsAg) tests is indispensable for consistent quality and comparability. Ideally, the assays should detect all known hepatitis B virus (HBV) genotypes equally well.

OBJECTIVE

Development of an HBV genotype reference panel for HBsAg assays representing the most prevalent HBV subgenotypes to address commutability and traceability of the heat-inactivated 2nd WHO International Standard (IS) for HBsAg in relation to native HBsAg and to HBV genotypes.

STUDY DESIGN

An HBV panel of 15 non-inactivated lyophilized specimens representing the subgenotypes A1, A2, B1, B2, C2, D1-D3, E, F2, and H was evaluated in parallel to the IS by 15 laboratories using 19 different HBsAg tests and tree unitages. The virus content of the samples was reduced by ultracentrifugation and dilution to <2×10(4) IU HBV DNA/mL.

RESULTS

Twenty-two qualitative and 6 quantitative data sets were evaluated. Overall, the results demonstrated consistent detection of HBV genotypes by the majority of tests with a mean potency variability relative to the IS of 36%. Some assays showed significant genotype-dependent differences in analytical sensitivity. Some tests were more sensitive with the IS, others less. On average, one IU HBsAg corresponded to 0.88±0.20 ng HBsAg protein.

CONCLUSIONS

The panel was accepted by the WHO as the "1st International Reference Panel for HBV genotypes for HBsAg-based assays". The panel is a helpful complementation to the IS to validate HBV genotype specific analytical test sensitivities.

Case report: detection of a hepatitis B surface antigen variant emerging in an elderly patient after an ischemic cerebral vascular accident

HBV reactivations are observed frequently in patients with past hepatitis B infection receiving cytotoxic and/or immunosuppressive chemotherapy for hemato-oncological malignancies or autoimmune diseases. Recent ischemic stroke was shown to induce immunodepression by misunderstood mechanisms. To our knowledge, the association between HBV reactivation and ischemic stroke has not been reported before. This study reports the case of an anti-HBs- and anti-HBc-positive patient who presented HBV reactivation in a context of recent ischemic stroke, with no other intercurrent iatrogenic phenomenon or usual immunosuppressive pathology.

Investigating the impact of hepatitis B virus surface gene polymorphism on antigenicity using ex vivo phenotyping

The hepatitis B virus (HBV) surface antigen (HBsAg) is a complex protein, and understanding accurately the impact of amino acid changes on the antigenicity of the immunodominant a determinant must take this complexity into consideration. Epitope mapping with four mAbs was used to phenotype HBsAg directly from patients’ sera to investigate the effect of mutations in their native genetic backbone. The expected mAb reactivity was established initially for samples harbouring ‘wild-type’ HBsAg sequences across genotypes A–E. The alteration of HBsAg antigenicity, defined by mAb epitope loss, was demonstrated in a number of samples with sequence-inferred amino acid changes. Individual mutations within the mapped epitopes to which the mAbs were directed usually affected their binding. However, the loss of more than one epitope was observed as the number of mutations within a sequence increased. Conversely, not all mutations occurring in the a determinant altered the HBsAg conformation. The genotype backbone, the specific amino acid substitution and amino acid changes occurring outside the major antigenic region appeared to be important in determining expression of the predicted epitope loss. These data clearly demonstrate that sequence-based methods alone may not accurately define HBsAg phenotype. This phenotyping methodology allows for the rapid and accurate identification of antigenically altered viruses and will greatly enhance current HBV surveillance, research and diagnostic activities. The data generated can be used to inform on public health issues relating to prevalence, transmission and impact of HBsAg mutants in HBV-infected populations.