An international collaborative study to establish a World Health Organization international standard for hepatitis B virus DNA nucleic acid amplification techniques

Early Dynamics of Hepatitis B Virus (HBV)-DNA and Surface Antigen (HBsAg) in Ramp-Up Phase of Viremia: Implications for Performance Evaluation of Blood Screening Assays

The Common Specifications/EU 2017/746 regulation for market approval of class D in vitro diagnostic devices (IVDs) intended for detection of blood borne viruses requires testing of the International Standard and 10–30 seroconversion panels to demonstrate ‘state of the art’ assay performance. We examined whether these requirements for performance evaluation are reasonable for HBV-DNA and HBsAg assays. For this purpose, we quantified HBsAg and HBV-DNA (genotype A) in the ramp-up phase of five seroconversion panels and demonstrated a remarkably parallel increase in the Log concentration of both analytes over time. Testing of seroconversion panels by three nucleic acid amplification technology (NAT) methods in multiple replicates and probit analysis with sufficient critical samples from all five panels taken together showed detection limits in copies/mL that were comparable to those on a HBV-DNA genotype A standard dilution panel. This indicates that the viral doubling time in the ramp-up phase is equal above and below the quantification limit of the viral load assay. The geometric mean HBsAg (PRISM) cutoff crossing point was 20 days later than the 50% NAT (Ultrio Plus) conversion point equivalent to 1500 (range: 1100–2200) and 4.8 (CI: 3.7–6.4) HBV-DNA copies/mL, respectively. Analytical sensitivity data of different NAT assay versions obtained over a decade demonstrated that the detection limit on the International Standard is not representative of all genotyped reference samples. From our detailed mathematical analysis, we conclude that HBV-DNA and HBsAg standard dilution series are functionally equivalent to seroconversion panels. A general requirement of a 95% detection limit ≤100 HBV-DNA copies/mL for different viral genotypes would be a better-defined regulation for EU market approval of NAT blood screening assays than the testing of multiple seroconversion panels to claim ‘state of the art’ performance.

Adaptation of a Public–Private Partnership Model for the Implementation of Minipool Nucleic Acid Testing for Screening Routine Blood Donations and the Evaluation of Assay: A Multi-Center Study from Odisha, India

Background Nucleic acid amplification testing (NAT) for the screening of blood donations is known to improve blood safety. The decision to initiate NAT requires careful deliberation of infrastructure, skilled manpower, and financial resources. This report outlines the initiative of the Government of Odisha to implement NAT screening in government blood banks in the state of Odisha, India, through public–private partnership (PPP) and evaluates the incremental yield of minipool NAT screening over serology testing of blood donations.

Methods Blood donations collected between June 2016 and September 2018 were initially screened for HBV (HBsAg), HCV (anti-HCV), and HIV (anti-HIV-1 and HIV-2) by ELISA, and syphilis and malaria. Sero-nonreactive donations were further screened in pools of six by Roche cobas TaqScreen MPX test version 2.0 (MPX2) NAT.

Results On screening 3,39,472 blood donations, 1.34% seroreactive donations were detected. In all, 847 NAT-reactive donations (0.26%): 693 HBV, 58 HCV, and 96 HIV were detected. The NAT yields were 1:386 overall, 1:472 for HBV, 1:5642 for HCV, and 1:3409 for HIV.

Conclusion NAT testing using the highly sensitive MPX2 assay leads to incremental detection of TTIs over serology. Implementation of NAT along with serological testing in blood centers all over India will be an important step towards providing safe blood. Our study not only highlights the benefits of minipool NAT testing but also presents a scalable PPP model that can serve as a template for application across other states.

Sensitive, Single-Pot, Two-Stage Assay for Hepatitis Viruses

When left untreated, hepatitis B virus (HBV) and hepatitis C virus (HCV) infections may cause severe illnesses. Since these infections remain asymptomatic for many years, routine screening of populations at risk is critical for therapy initiation. The current standard of care mandates a screening antibody test for HCV, followed by a confirmatory laboratory-based molecular test and treatment. Multiple visits to the clinic are inconvenient, and many patients fail to follow up. To address this challenge, we have developed sensitive, two-stage, isothermal molecular (Penn-RAMP) point-of-care tests to enable test and treat strategy. Penn-RAMP's first stage is comprised of recombinase polymerase amplification (RPA), while its second stage is comprised of loop-mediated isothermal amplification (LAMP). Penn-RAMP is more sensitive than LAMP or RPA alone. We designed a custom pre-LAMP buffer to maximize the volume of RPA products that can be added to the LAMP reaction mix without inhibition and forward and backward primers. Penn-RAMP was implemented in a single pot comprised of two compartments separated by a thermally removable barrier. RAMP's first stage is carried out above the barrier at the RPA incubation temperature. When the pot is heated to the LAMP incubation temperature, the barrier melts away, and the RPA reaction volume mixes with the pre-LAMP buffer, facilitating second-stage amplification. This entire process can be carried out with minimal instrumentation. Our HBV and HCV tests detect, respectively, as few as 10 and 25 virions within 30 min. The viral load can be estimated based on signal threshold time.

Viral Biomarkers for Hepatitis B Virus-Related Hepatocellular Carcinoma Occurrence and Recurrence

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide and the fourth leading cause of cancer-related death. The most common risk factor for developing HCC is chronic infection with hepatitis B virus (HBV). Early stages of HBV-related HCC (HBV-HCC) are generally asymptomatic. Moreover, while serum alpha-fetoprotein (AFP) and abdominal ultrasound are widely used to screen for HCC, they have poor sensitivity. Thus, HBV-HCC is frequently diagnosed at an advanced stage, in which there are limited treatment options and high mortality rates. Serum biomarkers with high sensitivity and specificity are crucial for earlier diagnosis of HCC and improving survival rates. As viral-host interactions are key determinants of pathogenesis, viral biomarkers may add greater diagnostic power for HCC than host biomarkers alone. In this review, we summarize recent research on using virus-derived biomarkers for predicting HCC occurrence and recurrence; including circulating viral DNA, RNA transcripts, and viral proteins. Combining these viral biomarkers with AFP and abdominal ultrasound could improve sensitivity and specificity of early diagnosis, increasing the survival of patients with HBV-HCC. In the future, as the mechanisms that drive HBV-HCC to become clearer, new biomarkers may be identified which can further improve early diagnosis of HBV-HCC.

Development of a reference standard for the detection and quantification of Mycobacterium avium subsp. paratuberculosis by quantitative PCR

Quantitative PCR (qPCR) has become a frequently employed direct method for the detection and quantification of Mycobacterium avium subsp. paratuberculosis (MAP). The quantity of MAP determined by qPCR, however, may be affected by the type of qPCR quantification standard used (PCR product, plasmid, genomic DNA) and the way in which standard DNA quantity is determined (absorbance, fluorescence). In practice, this can be reflected in the inability to properly compare quantitative data from the same qPCR assays in different laboratories. Thus, the aim of this study was to prepare a prototype of an international MAP reference standard, which could be used to calibrate routinely used qPCR quantification standards in various laboratories to promote clinical data comparability. Considering stability, storage and shipment issues, a lyophilised fecal suspension artificially contaminated with a MAP reference strain was chosen as the most suitable form of the standard. The effect of five types of lyophilisation matrices on standard stability was monitored on 2-weeks interval basis for 4 months by F57 qPCR. The lyophilisation matrix with 10% skimmed milk provided the best recovery and stability in time and was thus selected for subsequent comparative testing of the standard involving six diagnostic and research laboratories, where DNA isolation and qPCR assay procedures were performed with the parallel use of the identical supplied genomic DNA solution. Furthermore, the effect of storage conditions on the standard stability was tested for at least 6 months. The storage at room temperature in the dark and under light, at + 4 °C, - 20 °C and - 80 °C showed no significant changes in the stability, and also no substantial changes in MAP viability were found using phage amplification assay. The prepared MAP quantification standard provided homogeneous and reproducible results demonstrating its suitability for utilisation as an international reference qPCR standard.

Residual HBV DNA and pgRNA viraemia is associated with hepatocellular carcinoma in chronic hepatitis B patients on antiviral therapy

BACKGROUND

We aimed to assess whether residual hepatitis B virus (HBV) viraemia is associated with HCC development.

METHODS

This is a case-control study of 104 patients [52 HCC and 52 non-HCC (matched with age, gender, cirrhosis and treatment duration)] on ≥ 3 years entecavir (ETV) with unquantifiable HBV DNA by Cobas Taqman assay v2.0 (Roche Diagnostics; lower limit of quantification [LLOQ] 20 IU/mL). Serial sera within 1, 1-2, and > 2 years prior to HCC diagnosis or last follow-up (LFU) were measured for HBV DNA and pre-genomic (pg) RNA using a highly sensitive semi-quantitative PCR assay with lower limit of detection of 10 IU/mL and LLOQ of 51.5 IU/mL, respectively.

RESULTS

Among the 104 patients (80.8% male, median age 61.2 years old, 38.5% cirrhosis, median duration of ETV 45.5 months), 38.5% and 9.6% HCC patients had undetectable serum DNA and pgRNA, respectively, compared to 65.4% and 36.5% in non-HCC patients; P = 0.005 & 0.001, respectively, at the time of HCC diagnosis/LFU. Detectable HBV DNA and pgRNA were associated with a higher 2-year risk of HCC development (HR 2.79, 95% CI 1.424-5.468 & HR 4.544, 95% CI 1.07-19.289, respectively). No significant differences were observed for qHBsAg levels between HCC and non-HCC patients.

CONCLUSIONS

More than 50% CHB patients on ETV with HBV DNA < LLOQ by standard assay had persistent viraemia as determined by a more sensitive assay. Detectable HBV DNA or pgRNA by more sensitive assays was associated with HCC development. More potent viral suppression is required to further reduce the risk of HCC.

Nucleic acid sample preparation from whole blood in a paper microfluidic device using isotachophoresis

Nucleic acid amplification tests (NAATs) are a crucial diagnostic and monitoring tool for infectious diseases. A key procedural step for NAATs is sample preparation: separating and purifying target nucleic acids from crude biological samples prior to nucleic acid amplification and detection. Traditionally, sample preparation has been performed with liquid- or solid-phase extraction, both of which require multiple trained user steps and significant laboratory equipment. The challenges associated with sample preparation have limited the dissemination of NAAT point-of-care diagnostics in low resource environments, including low- and middle-income countries. We report on a paper-based device for purification of nucleic acids from whole blood using isotachophoresis (ITP) for point-of-care NAATs. We show successful extraction and purification of target nucleic acids from large volumes (33 µL) of whole human blood samples with no moving parts and few user steps. Our device utilizes paper-based buffer reservoirs to fully contain the liquid ITP buffers and does not require complex filling procedures, instead relying on the natural wicking of integrated paper membranes. We perform on-device blood fractionation via filtration to remove leukocytes and erythrocytes from our sample, followed by integrated on-paper proteolytic digestion of endogenous plasma proteins to allow for successful isotachophoretic extraction. Paper-based isotachophoresis purifies and concentrates target nucleic acids that are added directly to recombinase polymerase amplification (RPA) reactions. We show consistent amplification of input copy concentrations of as low as 3 × 10³ copies nucleic acid per mL input blood with extraction and purification taking only 30 min. By employing a paper architecture, we are able to incorporate these processes in a single, robust, low-cost design, enabling the direct processing of large volumes of blood, with the only intermediate user steps being the removal and addition of tape. Our device represents a step towards a simple, fully integrated sample preparation system for nucleic acid amplification tests at the point-of-care.

Distinct disease features in chimpanzees infected with a precore HBV mutant associated with acute liver failure in humans

Transmission to chimpanzees of a precore hepatitis B virus (HBV) mutant implicated in acute liver failure (ALF) in humans did not cause ALF nor the classic form of acute hepatitis B (AHB) seen upon infection with the wild-type HBV strain, but rather a severe AHB with distinct disease features. Here, we investigated the viral and host immunity factors responsible for the unusual severity of AHB associated with the precore HBV mutant in chimpanzees. Archived serial serum and liver specimens from two chimpanzees inoculated with a precore HBV mutant implicated in ALF and two chimpanzees inoculated with wild-type HBV were studied. We used phage-display library and next-generation sequencing (NGS) technologies to characterize the liver antibody response. The results obtained in severe AHB were compared with those in classic AHB and HBV-associated ALF in humans. Severe AHB was characterized by: (i) the highest alanine aminotransferase (ALT) peaks ever seen in HBV transmission studies with a significantly shorter incubation period, compared to classic AHB; (ii) earlier HBsAg clearance and anti-HBs seroconversion with transient or undetectable hepatitis B e antigen (HBeAg); (iii) limited inflammatory reaction relative to hepatocellular damage at the ALT peak with B-cell infiltration, albeit less extensive than in ALF; (iv) detection of intrahepatic germline antibodies against hepatitis B core antigen (HBcAg) by phage-display libraries in the earliest disease phase, as seen in ALF; (v) lack of intrahepatic IgM anti-HBcAg Fab, as seen in classic AHB, but at variance with ALF; and (vi) higher proportion of antibodies in germline configuration detected by NGS in the intrahepatic antibody repertoire compared to classic AHB, but lower than in ALF. This study identifies distinct outcome-specific features associated with severe AHB caused by a precore HBV mutant in chimpanzees, which bear closer resemblance to HBV ALF than to classic AHB. Our data suggest that precore HBV mutants carry an inherently higher pathogenicity that, in addition to specific host factors, may play a critical role in determining the severity of acute HBV disease.

Laboratory Diagnosis and Monitoring of Viral Hepatitis

Many microbes, toxins, autoimmune diseases, and neoplastic diseases may cause liver inflammation; however, 5 viruses whose main pathogenesis is liver disease are referred to as hepatitis A, B, C, D, and E viruses. These viruses cause a significant burden of global illness. With the exception of hepatitis A virus, all may cause chronic infection potentially leading to cirrhosis and hepatocellular carcinoma. Excellent serologic and nucleic acid detection methods are available for determining the precise cause and, in some cases, the duration of infection. Diagnostics are critical for identifying individuals needing treatment and for monitoring the treatment success.

Standardization of Nucleic Acid Tests: the Approach of the World Health Organization

The first World Health Organization (WHO) international standards (ISs) for nucleic acid amplification techniques were established two decades ago, with the initial focus on blood screening for three major viral targets, i.e., hepatitis C virus, hepatitis B virus, and human immunodeficiency virus 1. These reference materials have subsequently found utility in the diagnosis and monitoring of a wide range of infectious diseases in clinical microbiology laboratories worldwide. WHO collaborating centers develop ISs and coordinate international studies for their evaluation. The WHO Expert Committee on Biological Standardization is responsible for the endorsement of new standardization projects and the establishment of new and replacement ISs. Potencies of ISs are defined in international units (IU); the reporting in IU for assays calibrated with an IS (or secondary standards traceable to the IS) facilitates comparability of results for different assays and determination of assay parameters such as analytical sensitivities.

Plasma microRNA: A novel non-invasive biomarker for HBV-associated liver fibrosis staging

The aim of the present study was to evaluate the potential use of 7 plasma miRNAs for liver fibrosis staging in patients with chronic hepatitis B virus (HBV) infection. Relative levels of miRNAs were measured using quantitative polymerase chain reaction and used to develop a diagnostic panel. A receiver operating characteristic (ROC) curve was drawn to evaluate the performance of individual miRNAs and the whole panel. It was identified that hsa-miR-122 exhibited significantly different expression levels between F4 and F3, F2, F1, and F0 fibrosis stages (P<0.05), and between F2 and F1 stages (P=0.045); hsa-miR-146a-5p, hsa-miR-29c-3p and hsa-miR-223 exhibited significantly different expression levels between F4 and F0 stages. ROC analysis revealed that hsa-miR-122-5p, hsa-miR-223 and hsa-miR-29c-3p identified patients with ≥F2 fibrosis with area under the curve (AUC) =0.745, 0.631 and 0.670, respectively. hsa-miR-122-5p identified patients with ≥F3 disease (AUC=0.783). hsa-miR-122-5p, hsa-miR-223 and hsa-miR-29c-3p identified patients with cirrhosis with AUC=0.776, 0.617 and 0.619, respectively. The miRNA panel exhibited a higher accuracy compared with individual miRNAs in discriminating between ≥F2, ≥F3 and F4 fibrosis stages with AUC=0.904, 0.889 and 0.835, respectively. hsa-miR-122-5p, hsa-miR-146a, hsa-miR-29c and hsa-miR-223 were positively correlated with fibrosis stage. hsa-miR-122-5p and hsa-miR-381-3p were negatively correlated with alanine aminotransferase, aspartate transaminase and HBV viral DNA load. These 7 miRNAs may serve as potential biomarkers of liver fibrosis in patients with HBV-associated fibrosis. The miRNA panel may serve as a novel non-invasive method for liver fibrosis staging.

Modified PAGE-B score predicts the risk of hepatocellular carcinoma in Asians with chronic hepatitis B on antiviral therapy

BACKGROUND & AIMS

Recently, the PAGE-B score and Toronto HCC risk index (THRI) have been developed to predict the risk of hepatocellular carcinoma (HCC) in Caucasian patients with chronic hepatitis B (CHB). We aimed to validate PAGE-B scores and THRI in Asian patients with CHB and suggested modified PAGE-B scores to improve the predictive performance.

METHODS

From 2007 to 2017, we examined 3,001 Asian patients with CHB receiving entecavir/tenofovir therapy. We assessed the performances of PAGE-B, THRI, CU-HCC, GAG-HCC, and REACH-B for HCC development. A modified PAGE-B score (mPAGE-B) was developed (derivation set, n = 2,001) based on multivariable Cox models. Bootstrap for internal validation and external validation (validation set, n = 1,000) were performed.

RESULTS

The five-year cumulative HCC incidence rates were 6.6% and 7.2% in the derivation and validation datasets after entecavir/tenofovir onset. In the derivation dataset, age, gender, serum albumin levels, and platelet counts were independently associated with HCC. The mPAGE-B score was developed based on age, gender, platelet counts, and serum albumin levels (time-dependent area under receiver operating characteristic curves [AUROC] = 0.82). In the validation set, the PAGE-B and THRI showed similar AUROCs to CU-HCC, GAG-HCC, and REACH-B at five years (0.72 and 0.73 vs. 0.70, 0.71, and 0.61 respectively; all p >0.05 except REACH-B), whereas the AUROC of mPAGE-B at five years was 0.82, significantly higher than the five other models (all p <0.01). HCC incidence rates after initiation of entecavir/tenofovir therapy in patients with CHB were significantly decreased in all risk groups in long-term follow-up periods.

CONCLUSION

Although PAGE-B and THRI are applicable in Asian patients with CHB receiving entecavir/tenofovir therapy, mPAGE-B scores including additional serum albumin levels showed better predictive performance than the PAGE-B score.

LAY SUMMARY

PAGE-B scores and Toronto HCC risk index were developed to predict the risk of hepatocellular carcinoma (HCC) in Caucasian patients with CHB under potent antiviral therapy. This study validated these two scores in Asian patients with CHB and suggested that modified PAGE-B scores could improve the predictive performance. A modified PAGE-B score, which is based only on a patient's age, gender, baseline platelet counts, and serum albumin levels at treatment initiation, represents a reliable and easily available risk score to predict HCC development during the first five years of antiviral treatment in Asian patients with CHB. With a scoring range from 0 to 21 points, a modified PAGE-B score differentiates the HCC risk. A modified PAGE-B score significantly differentiates the five-year HCC risk: low ≤8 points and high ≥13 points.

Molecular Microbiology

Background

Nucleic acid (NA) amplification techniques are now commonly used to diagnose and manage patients with infectious diseases. The growth in the number of Food and Drug Administration–approved test kits and analyte-specific reagents has facilitated the use of this technology in clinical laboratories. Technological advances in NA amplification techniques, automation, NA sequencing, and multiplex analysis have reinvigorated the field and created new opportunities for growth. Simple, sample-in, answer-out molecular test systems are now widely available that can be deployed in a variety of laboratory and clinical settings. Molecular microbiology remains the leading area in molecular pathology in terms of both the numbers of tests performed and clinical relevance. NA-based tests have reduced the dependency of the clinical microbiology laboratory on more traditional antigen detection and culture methods and created new opportunities for the laboratory to impact patient care.

Content

This chapter reviews NA testing as it applies to specific pathogens or infectious disease syndromes, with a focus on those diseases for which NA testing is now considered the standard of care and highlights the unique challenges and opportunities that these tests present for clinical laboratories.

Diminished accuracy of biomarkers of fibrosis in low replicative chronic hepatitis B

Background

We evaluated the diagnostic accuracy of aspartate aminotransferase (AST)-to-platelet ratio index (APRI), fibrosis-4 index (FIB-4), AST/alanine aminotransferase (ALT) ratio (AAR), and age-platelet index (API) for significant fibrosis (Metavir F2–4) in low-replicative (HBV DNA <20,000 IU/mL) chronic hepatitis B virus (HBV) patients.

Methods

The sensitivity, specificity, and area under the receiver-operating characteristic curve (AUROC) of HBeAg-negative, low-replicative (n = 213) and high-replicative (HBV DNA ≥20,000 IU/mL, n = 153) patients was assessed.

Results

Overall, 113 patients (30.9%) had F2–4 fibrosis. Of the low and high-replicative patients, 40 (18.8%) and 73 (47.7%) had F2–4, respectively (P < 0.0001). APRI ≥0.5 less frequently identified F2–4 fibrosis in low vs. high-replicative patients (48.7% vs. 69.6%, P = 0.032) and AAR identified it more frequently in low-replicative patients (37.5% vs. 19.4%, P = 0.037). FIB-4 and API were not different (P > 0.05) for identifying F2–4 fibrosis in low and high-replicative patients. Higher specificities were seen at the lowest cut-offs in low vs. high-replicative states for APRI (≥0.5, 98% vs. 68.9%), AAR (84.3% vs. 76.6%), FIB-4 (≥1.45, 97.5% vs. 87.8%) and API (>4, 94.8% vs. 93.8%). At ROC-defined thresholds, APRI (≥0.33), AAR (≥0.93), FIB-4 (≥0.70) and API (>2) showed greater AUROCs for F2–4 diagnosis in low replicative (0.80, 0.62, 0.81 and 0.71, respectively) vs. high-replicative patients (0.73, 0.52, 0.67 and 0.69, respectively).

Conclusion

All 4 biomarkers in both, low and high-replicative HBV demonstrate modest accuracy for fibrosis diagnosis at conventional cut-offs. Lowering the cut-offs may increase the diagnostic relevance of these biomarkers, particularly for APRI and FIB-4 in low-replicative disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-017-0658-x) contains supplementary material, which is available to authorized users.

Commutability and concordance of four hepatitis B virus DNA assays in an international multicenter study

BACKGROUND

HBV DNA is the most important molecular marker in hepatitis B, used to determine treatment indication and monitoring. Most patients require lifelong hepatitis B virus (HBV) management, thus viral load (VL) monitoring may be performed at different laboratories, with different HBV assays, which may result in different VL results. This multicenter study compares the commutability and concordance of results from four different HBV DNA assays: CAP/CTM HBVv2, HPS/CTM HBVv2 and the new cobas 6800/8800 HBV and cobas 4800 HBV assays.

METHODS

Across all four assays, HBV limit of detection (LoD) and linearity at lower concentrations were assessed using panels traceable to the World Health Organization international standard, and concordance was investigated at the important medical decision cutoffs 2000 and 20,000 IU/ml, using specimens from HBV-positive patients.

RESULTS

The calculated LoD via a probit curve was 2.7 IU/ml for cobas 6800/8800 HBV, 2.8 IU/ml for cobas 4800 HBV, 9.6 IU/ml for CAP/CTM HBVv2, and 6.2 IU/ml for HPS/CTM HBVv2. The average accuracy was comparable between cobas 6800/8800 HBV, cobas 4800 HBV and CAP/CTM HBVv2 (0.04-0.05 log₁₀ IU/ml), while a slightly lower accuracy was documented for HPS/CTM HBVv2 (-0.16 log₁₀ IU/ml). A total of 211-245 clinical samples were used for a pairwise comparison. Mean paired log differences ranged from -0.17 log₁₀ IU/ml to -0.01 log₁₀ IU/ml. Coefficient of determination was over 98% for all pairs with high overall percent agreement at the 2000 and 20,000 IU/ml cutoffs (from 91.7% to 96.3%). In a subset of samples with VL±0.5 log₁₀ to the 2000 and 20,000 IU/ml thresholds, concordance was still 72% and 82%, respectively.

CONCLUSIONS

The new cobas 6800/8800 HBV and 4800 HBV assays show high accuracy in samples with low-level viremia and a high concordance with the established HBV tests, CAP/CTM HBVv2 and HPS/CTM HBVv2, at 2000 and 20,000 IU/ml. Thus, all four HBV assays have high commutability and may be used interchangeably in routine clinical practice.

Occult Hepatitis Infection in Transfusion Medicine: Screening Policy and Assessment of Current Use of Anti-HBc Testing

HBV still represents a global risk factor in transfusion medicine. The residual risk of HBV is not limited to pre-seroconversion window period but it extends to donors with occult HBV infection (OBI) characterized by the presence of HBV DNA in liver and by the absence of the virus surface antigen. Each country developed an appropriate blood screening policy according to local HBV prevalence, yields of infectious units per different screening methods and cost-effectiveness. We underline the need of maintaining a high level of attention for OBI carrier identification in all blood banks worldwide where the screening procedures are generally based on a combination of both serological markers and nucleic acid amplification test. In this context, markers such as hepatitis B surface antibodies and hepatitis B core antibodies (anti-HBc) might be useful, although the use of this latter is highly debated and still controversial. Our aim is to give an overview on the relevant diagnostic approaches for the routine screening for HBV focusing on the feasibility of anti-HBc testing as precautionary measure in preventing OBI transmission worldwide. In our tailored algorithm, the loss of about 1% of 'anti-HBc only' donors, does not significantly affect the blood supply while improving recipient safety.

Polymorphisms of chemokine receptor genes and clearance of hepatitis C virus infection in Chinese population

BACKGROUND

Chemokine genes play an essential role in both spontaneous clearance in acute infection and therapy of HCV. We investigated whether several CXC family-related genes associated with HCV spontaneous clearance and response to treatment.

METHODS

The current study genotyped four SNPs, respectively are CXCR6 rs2234358, CXCL12 rs1801157, CXCL9 rs10336, rs3733236 to assess their associations with HCV spontaneous clearance and response to treatment in a two stage study (668 chronic and 400 resolvers in discovery group, meanwhile 333 chronic and 199 resolver in replication group), and a treatment cohort of HCV with 282 patients.

RESULTS

We found that the CXCR6 rs2234358 was associated with HCV spontaneous clearance in Chinese Han population (dominant model: adjusted OR=1.62, 95%CI: 1.30-2.01; additive model: adjusted OR=1.43, 95%CI: 1.20-1.70). Patients carrying GT/TT genotypes had increased sustained virological response compared with patients carrying the GG genotype (dominant model: adjusted OR=2.23, 95%CI: 1.26-3.95).

CONCLUSION

These results suggest that CXCR6 rs2234358 is associated with spontaneous clearance of HCV and response to IFN-α/RBV therapy, which may be identified as a predictive marker in Chinese Han population of HCV.

Complete Genome Sequence of the WHO International Standard for Hepatitis B Virus DNA

The World Health Organization (WHO) international standard (IS) for hepatitis B virus (HBV) DNA for use in nucleic acid amplification assays was characterized by determining the complete genome sequence, which was assigned genotype A. This information will aid the design, development, and evaluation of HBV DNA amplification assays.

A collaborative study to establish the 3rd WHO International Standard for hepatitis B virus for nucleic acid amplification techniques

Nucleic acid amplification techniques (NAT) are routinely used for clinical diagnostics and monitoring hepatitis B virus (HBV) infections, and are implemented on a voluntary basis for blood screening. A collaborative study was performed to evaluate a replacement WHO International Standard for HBV for the standardization of NAT. Two lyophilised HBV candidates were evaluated by 16 laboratories worldwide, alongside the existing HBV International Standard. The overall mean potency estimates for the candidate samples 1 and 2, relative to sample 3 (2nd HBV International Standard), from quantitative assays, were 5.93 and 5.98 log₁₀ International Units (IU)/mL respectively. The variability in individual laboratory mean estimates for samples 1-3 for quantitative assays was ∼0.3 log₁₀ IU/mL. The inter-laboratory variability for qualitative assays was higher. Accelerated thermal degradation studies indicate that both lyophilised candidates are stable and suitable for long-term use. Overall, the results suggested that both candidates were suitable as replacement International Standards. Sample 1 (NIBSC code 10/264) was established as the 3rd WHO International Standard for HBV for NAT with an assigned potency of 850,000 IU/mL (∼5.93 log₁₀ IU/mL), when reconstituted in 0.5 mL of nuclease-free water. It is intended for the calibration (in IU) of secondary reference materials used in HBV NAT.

Entecavir for patients with lamivudine‐resistant chronic hepatitis B virus infection

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To evaluate the benefits and harms of entecavir versus no intervention, placebo, and non‐entecavir interventions in adults with lamivudine‐resistant, chronic hepatitis B virus infection.

Efficacy of entecavir and tenofovir in chronic hepatitis B under treatment in the public health system in southern Brazil

There are about 350 million hepatitis B virus (HBV) carriers worldwide and chronic HBV is considered a major public health problem. The objective of the present study was to assess the effectiveness of the nucleos(t)ide analogues tenofovir (TDF) and entecavir (ETV) in the treatment of chronic HBV. A cross-sectional study was carried out from March-December 2013, including all patients with chronic HBV, over 18 years of age, undergoing therapy through the public health system in southern Brazil. Only the data relating to the first treatments performed with TDF or ETV were considered. Retreatment, co-infection, transplanted or immunosuppressed patients were excluded. Six hundred and forty patients were evaluated, of which 336 (52.5%) received TDF and 165 (25.8%) ETV. The other 139 (21.7%) used various combinations of nucleos(t)ide analogues and were excluded. The negativation of viral load was observed in 87.3% and 78.8% and the negativation of hepatitis B e antigen was achieved in 79% and 72% of those treated with ETV or TDF, respectively. Negativation of hepatitis B surface antigen was not observed. There was no occurrence of adverse effects. This is a real-life study demonstrating that long-term treatment with ETV and TDF is both safe and effective.

Review of Laboratory Tests used in Monitoring Hepatitis B Response to Pegylated Interferon and Nucleos(t)ide Analog Therapy

There are only two currently approved classes of hepatitis B virus (HBV) antiviral agents, pegylated interferon (Peg-IFN), and nucleos(t)ide analogs (NAs) for chronic HBV infection. Although Peg-IFN is used for a finite 48-week duration and offers a greater chance of sustained off-treatment virological response, it is poorly tolerated and can only be offered to selected patients. The NAs are well tolerated but require prolonged therapy due to risk of relapse with treatment cessation. There is evolving data that novel virological assays (e.g., quantitative hepatitis B surface antigen, quantitative hepatitis B core antigen, quantitative antibody to core protein) in combination with hepatitis B genotype and more sensitive HBV DNA polymerase chain reaction (PCR) assays may be useful to predict response to IFN as well as off-treatment NA durability. Utilization of these clinical laboratory tests may be important given the development of novel anti-HBV therapies, hoping to achieve a cure for chronic hepatitis B infection.

Virological and serological tools to optimize the management of patients with chronic hepatitis B

Molecular biology techniques are routinely used to diagnose and monitor treatment in patients with chronic hepatitis B (CHB). These tools can detect and quantify viral genomes and analyse their sequences to determine genotype. The increasing use of these tools to monitor patients has greatly improved the management of CHB infection by maximizing the potential for individualized treatment. HBV genotyping has become increasingly important and provides additional information to predict a response to therapy. More sensitive methods to determine HBV DNA levels are now available and the units of measurements have been standardized. HBsAg levels in serum have been shown to reflect active intrahepatic covalently closed circular DNA (cccDNA) and to have additional value in treatment decisions, especially as an on-treatment marker.

A novel polymorphism near HLA class II region is associated with spontaneous clearance of HCV and response to interferon treatment in Chinese patients

A recent genome-wide association study (GWAS) has identified the single-nucleotide polymorphism (SNP) rs4273729 in a 100-kbp region comprising human leukocyte antigens (HLAs) class II genes as an important predictor of hepatitis C virus (HCV) clearance in European and African populations. This study was to determine whether this polymorphism is also associated with spontaneous HCV clearance as well as response to interferon treatment in Chinese patients. Thus, 686 chronic HCV carriers, 432 individuals with spontaneous viral clearance and 243 patients with pegylated interferon-α and ribavirin (PEG IFN-α/RBV) treatment were genotyped. The rs4273729 GG genotype was strongly associated with spontaneous HCV clearance as well as better IFN/RBV treatment response compared with the GC/CC genotypes in Chinese Han population (additive model: odds ratio (OR)=0.62, 95% confidence interval (95% CI)=0.51-0.76; OR=0.58, 95% CI=0.38-0.88, respectively). Rs4273729, rs12980275, baseline HCV RNA and platelet level were independent predictors for sustained virological response (SVR). The area under the receiver-operating characteristic curve (AUC) was 0.578 when including rs4273729 alone, but the prediction value was improved significantly (AUC=0.733) when further including rs12980275, baseline viral load and baseline platelet level. In conclusion, the genetic variation of rs4273729 is associated with clearance of HCV in both the natural course and the treatment process in Chinese Han population.

Poor efficacy of nucleic acid testing in identifying occult HBV infection and consequences for safety of blood supply in Italy

BACKGROUND & AIMS

In Italy, DNA screening of blood donations for hepatitis B virus (HBV) was introduced to prevent the transmission of window period and occult HBV infection. Anti-HBc screening is not recommended in order to avoid shortage of the blood supply. To contain costs, donor samples are generally pooled before testing. We evaluated the safety of this national policy using a prospective repository of donors/recipient pairs.

METHODS

We used highly sensitive nucleic acid testing (NAT) assays to test repository and follow-up samples from donors who were initially classified as negative by minipool NAT assays (6-MP), but were later found to carry occult HBV DNA. When available, we also analysed recipients' pre- and post-transfusion samples, collected in the context of a repository financed by the European Commission (the BOTIA project).

RESULTS

Between 2008 and 2011 6-MP NAT assays identified 18 carriers of occult HBV infection among 12,695 donors; 28 samples from previous donations were available from 13 of these carriers. Highly sensitive HBV DNA detection methods showed that 6-MP HBV DNA screening failed to identify 14/28 (50%) viraemic donations, that were released for transfusion. HBV marker testing of such blood product recipients revealed two cases of transfusion transmitted HBV infection, documented by donor-recipient sequence identity.

CONCLUSIONS

Viraemic blood donations from occult HBV infection carriers remain undetected by current minipool HBV DNA screening, and transfusion transmission of HBV continues to occur in susceptible patients. More effective individual HBV DNA screening and/or tests for antibodies to HBV core antigen should be considered to improve blood safety.

A Treatment Algorithm for the Management of Chronic Hepatitis B Virus Infection in the United States: 2015 Update

Chronic hepatitis B (CHB) continues to be an important public health problem worldwide, including in the United States. An algorithm for managing CHB was developed by a panel of United States hepatologists in 2004 and subsequently updated in 2006 and 2008. Since 2008, additional data on long-term safety and efficacy of licensed therapies have become available and have better defined therapeutic options for CHB. The evidence indicates that potent antiviral therapy can lead to regression of extensive fibrosis or even cirrhosis, thus potentially altering the natural history of CHB. In addition, appropriate choice of antiviral agent can minimize the risk of resistance. This updated algorithm for managing CHB is based primarily on evidence from the scientific literature. Where data were lacking, the panel relied on clinical experience and consensus expert opinion. The primary aim of antiviral therapy for CHB is durable suppression of serum hepatitis B virus (HBV) DNA to low or undetectable levels. CHB patients who have HBV DNA >2000 IU/mL, elevated alanine aminotransferase level, and any degree of fibrosis should receive antiviral therapy regardless of their hepatitis B e antigen status. CHB patients with HBV DNA >2000 IU/mL and elevated alanine aminotransferase level but no evidence of fibrosis may also be considered for antiviral therapy. Approved antiviral therapies for CHB are interferon alfa-2b, peginterferon alfa-2a, lamivudine, adefovir, entecavir, telbivudine, and tenofovir, although the preferred first-line treatment choices are peginterferon alfa-2a, entecavir, and tenofovir. In determining choice of therapy, considerations include efficacy, safety, rate of resistance, method of administration, duration, and cost.

Studies of nosocomial outbreaks of hepatitis B in nursing homes in Germany suggest a major role of hepatitis B e antigen expression in disease severity and progression

Hepatitis B virus (HBV) causes acute or chronic hepatitis B. Local outbreaks of HBV infections in skilled nursing facilities is a matter of growing concern in developed countries. Here, we investigated two outbreaks of hepatitis B that recently occurred in nursing homes in Germany. The outbreak at location A was associated with acute fulminant hepatitis with fatal outcome in several cases, while individuals infected at location B developed asymptomatic or mild hepatitis B. Sequence analysis of viruses involved in these outbreaks revealed different, but unique HBV strains for each location. Each of the strains produced high viremia of more than 10(9) virions/mL serum. We found that the mild course of hepatitis B at location B was caused by a circulating wild-type HBV genotype A2 strain, which is commonly found in Central Europe. Complete genome sequences of isolates obtained from infected patients revealed nearly 100% sequence identity at the nucleotide level as well as expression of HBV e protein (HBeAg), a known T cell tolerogen in the incubation or chronic phases of HBV infection. By contrast, the outbreak at location A was associated with an HBV genotype D2 variant that lacked HBeAg expression, suggesting that immunopathology and selection of specific HBV variants played a major role in the severe (or even fulminant) acute hepatitis observed at location A. Importantly, all patients were diagnosed with type 2 diabetes mellitus, a known risk factor for healthcare-associated transmission of HBV. The study leads us to suggest that, besides strict adherence to hygiene standards, additional efforts are required to reduce the risk of HBV transmission and fulminant disease progression in healthcare settings and nursing homes. In this context, a general screening for HBsAg and active hepatitis B vaccination should be considered for people living in nursing homes, especially for those with diagnosed diabetes or other predisposing factors for HBV transmission.

Standardization of NAT for Blood-Borne Pathogens

Assays based on nucleic acid amplification technology (NAT) are increasingly used for screening of blood and for diagnosis or monitoring of patients. Both regulatory requirements for blood screening and international recommendations for the treatment of patients are based on common reference materials available globally for the standardization of NAT assays. World Health Organization International Standards (WHO ISs) and International Reference Panels (WHO IRPs) are primary reference materials. The characterization and manufacture of WHO reference materials as well as their evaluation is performed on behalf of the WHO by collaborating centers; their establishment is decided upon by the WHO Expert Committee on Biological Standardization (ECBS). The potency of the first WHO IS is defined by the 'international unit' (IU) which should be maintained upon replacement of the IS. The IU, unlike copy number or genome equivalent, is defined by the IS with a physical existence, is available worldwide, and allows traceability and comparability of results. The anticipated use of WHO ISs is the calibration of secondary standards or the validation of essential assay features, e.g. limit of detection.

Hepatocellular carcinoma risk in HBeAg-negative chronic hepatitis B patients with or without cirrhosis treated with entecavir: HepNet.Greece cohort

Hepatocellular carcinoma (HCC) may still develop in chronic hepatitis B (CHB) patients treated with lamivudine. Whether HCC rates are comparable in patients treated with the current first-line antivirals remains uncertain. We estimated the incidence and evaluated predictors of HCC in a large nationwide prospective cohort (HepNet.Greece) of HBeAg-negative CHB patients treated with entecavir. HBeAg-negative CHB patients from the same cohort who were initially treated with lamivudine were used as controls. We included 321 patients treated with entecavir for a median of 40 months and 818 patients treated initially with lamivudine for a median of 60 months. In the entecavir group, HCC developed in 4 of 321 (1.2%) patients at a median of 1.5 (range: 1.0-4.5) years, while the cumulative HCC incidence was significantly higher in cirrhotics than noncirrhotics (1, 3, 5 years: 0%, 3%, 9% vs 1%, 1%, 1%; P = 0.024) and in older patients (P = 0.026). Entecavir compared with lamivudine group patients had lower HCC incidence (1, 3, 5 years: 0.3%, 1.2%, 2.8% vs 0.7%, 3.8%, 5.6%; P = 0.024). However, in multivariable Cox regression analysis, the HCC risk was independently associated with older age (P < 0.001), male gender (P = 0.011) and cirrhosis (P = 0.025), but not with the initial agent. In conclusion, our large nationwide study indicates that the HCC risk remains increased in entecavir-treated HBeAg-negative CHB patients with cirrhosis, particularly of older age, at least for the first 5 years. The HCC risk does not seem to be significantly reduced with entecavir compared with antiviral therapy starting with lamivudine.

The incidence of hepatocellular carcinoma is reduced in patients with chronic hepatitis B on long-term nucleos(t)ide analogue therapy

BACKGROUND

North American data are lacking on the effect of nucleos(t)ide analogues (NA) in preventing chronic hepatitis B (CHB)-related hepatocellular carcinoma (HCC).

AIM

To determine the incidence of HCC in NA-treated patients and compare this risk with that predicted without treatment based on the REACH-B model.

METHODS

In this retrospective study, the incidence of HCC was determined in CHB patients initiated on NA from 1999 to 2012. Pre-treatment data utilised in the REACH-B model were used to predict the annual HCC risk. The standardised incidence ratio (SIR) for HCC was calculated by comparing the observed to expected number of cases, and HCC risk factors determined by Cox proportional hazards regression.

RESULTS

Five hundred and forty nine initiated NA (14% lamivudine, 5% adefovir, 1.5% telbivudine, 39% entecavir, 41% tenofovir). Over a median follow-up of 3.2 years (IQR 1.9-4.6), 11 (3.2%) were diagnosed with HCC. Among 322 with data to calculate the REACH-B model, the median age at treatment initiation was 46 years (IQR 38-55), 65% were male, 32% HBeAg positive and 20% had cirrhosis. The median pre-treatment ALT was 71 U/L (IQR 41-127) and HBV DNA was 6.48 log10 copies/mL (4.95-8.04). The observed annual HCC incidence (0.9%; 95% CI 0.5-1.7) was significantly lower than predicted without treatment by the REACH-B model (SIR 0.46; 95% CI 0.23-0.82); this risk was reduced after 4 years of therapy (SIR 0.49; 95% CI 0.2-1.00).

CONCLUSIONS

In this Canadian study of nucleos(t)ide analogues-treated patients with chronic hepatitis B, the incidence of HCC was lower than expected, suggesting that NA reduce the risk of chronic hepatitis B-related HCC.

Management of chronic hepatitis B infection

The spectrum of chronic hepatitis B infection in children ranges from asymptomatic carriage with minimal disease, to progression to cirrhosis and risk of hepatocellular carcinoma in adulthood. Identifying those who will benefit from treatment is a challenge. Interferon-based therapies have limited efficacy, while prolonged use of nucleos(t)ide analogues may promote resistance. New antiviral agents have improved barriers to resistance, but long-term outcome is not yet known. Untreated infection, however, may in some, lead to natural seroconversion and reduce risk of further disease. Hepatitis B e antigen-positive infection is the most common scenario in chronically infected children, with e antigen-negative hepatitis rarely encountered. This paper reviews the clinical guidelines published in 2013 by the National Institute for Health and Care Excellence (NICE) and the European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN), and focuses on the guidance for treatment in e antigen-positive children. The most significant difference is the lower threshold for starting treatment recommended by NICE guidelines. The need for regular evaluation of each child, in the light of new evidence and new drugs as they emerge, must remain the focus of each clinician involved in the care of children with hepatitis B virus infection.

Recent advances in molecular diagnostics of hepatitis B virus

Hepatitis B virus (HBV) is one of the important global health problems today. Infection with HBV can lead to a variety of clinical manifestations including severe hepatic complications like liver cirrhosis and hepatocellular carcinoma. Presently, routine HBV screening and diagnosis is primarily based on the immuno-detection of HBV surface antigen (HBsAg). However, identification of HBV DNA positive cases, who do not have detectable HBsAg has greatly encouraged the use of nucleic acid amplification based assays, that are highly sensitive, specific and are to some extent tolerant to sequence variation. In the last few years, the field of HBV molecular diagnostics has evolved rapidly with advancements in the molecular biology tools, such as polymerase chain reaction (PCR) and real-time PCR. Recently, apart of PCR based amplification methods, a number of isothermal amplification assays, such as loop mediated isothermal amplification, transcription mediated amplification, ligase chain reaction, and rolling circle amplification have been utilized for HBV diagnosis. These assays also offer options for real time detection and integration into biosensing devices. In this manuscript, we review the molecular technologies that are presently available for HBV diagnostics, with special emphasis on isothermal amplification based technologies. We have also included the recent trends in the development of biosensors and use of next generation sequencing technologies for HBV.

Viral expression and molecular profiling in liver tissue versus microdissected hepatocytes in hepatitis B virus-associated hepatocellular carcinoma

Background

The molecular mechanisms whereby hepatitis B virus (HBV) induces hepatocellular carcinoma (HCC) remain elusive. We used genomic and molecular techniques to investigate host-virus interactions by studying multiple areas of the same liver from patients with HCC.

Methods

We compared the gene signature of whole liver tissue (WLT) versus laser capture-microdissected (LCM) hepatocytes along with the intrahepatic expression of HBV. Gene expression profiling was performed on up to 17 WLT specimens obtained at various distances from the tumor center from individual livers of 11 patients with HCC and on selected LCM samples. HBV markers in liver and serum were determined by real-time polymerase chain reaction (PCR) and confocal immunofluorescence.

Results

Analysis of 5 areas of the liver showed a sharp change in gene expression between the immediate perilesional area and tumor periphery that correlated with a significant decrease in the intrahepatic expression of HB surface antigen (HBsAg). The tumor was characterized by a large preponderance of down-regulated genes, mostly involved in the metabolism of lipids and fatty acids, glucose, amino acids and drugs, with down-regulation of pathways involved in the activation of PXR/RXR and PPARα/RXRα nuclear receptors, comprising PGC-1α and FOXO1, two key regulators critically involved not only in the metabolic functions of the liver but also in the life cycle of HBV, acting as essential transcription factors for viral gene expression. These findings were confirmed by gene expression of microdissected hepatocytes. Moreover, LCM of malignant hepatocytes also revealed up-regulation of unique genes associated with cancer and signaling pathways, including two novel HCC-associated cancer testis antigen genes, NUF2 and TTK.

Conclusions

Integrated gene expression profiling of whole liver tissue with that of microdissected hepatocytes demonstrated that HBV-associated HCC is characterized by a metabolism switch-off and by a significant reduction in HBsAg. LCM proved to be a critical tool to validate gene signatures associated with HCC and to identify genes that may play a role in hepatocarcinogenesis, opening new perspectives for the discovery of novel diagnostic markers and therapeutic targets.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-014-0230-1) contains supplementary material, which is available to authorized users.

Mortality, liver transplantation, and hepatocellular carcinoma among patients with chronic hepatitis B treated with entecavir vs lamivudine

BACKGROUND & AIMS

Little is known about whether the antiviral agent entecavir is more effective than a less potent drug, lamivudine, in reducing the risk of death and hepatocellular carcinoma (HCC) in patients with chronic hepatitis B.

METHODS

We performed a retrospective analysis of data from 5374 consecutive adult patients with chronic hepatitis B, treated with entecavir (n = 2000) or lamivudine (n = 3374), at a tertiary referral hospital in Seoul, Korea, from November 1, 1999, through December 31, 2011. Data were collected from patients for up to 6 years and analyzed by a multivariable Cox proportional hazards model for the entire cohort and for propensity score-matched cohorts.

RESULTS

During the study period, 302 patients (5.6%) died, 169 (3.1%) received a liver transplant, and 525 (9.8%) developed HCC. Multivariable analyses showed that compared with lamivudine, entecavir therapy was associated with a significantly lower risk of death or transplantation (hazard ratio [HR], 0.49; 95% confidence interval [CI], 0.38-0.64), but a similar risk of HCC (HR, 1.08; 95% CI, 0.87-1.34). In the 1792 overall propensity-matched pairs, entecavir again was associated with a significantly lower risk of death or transplantation (HR, 0.49; 95% CI, 0.37-0.64) and a similar risk of HCC (HR, 1.01; 95% CI, 0.80-1.27). Entecavir also reduced the risk of death or transplantation, compared with lamivudine, in 860 pairs of patients with cirrhosis (HR, 0.42; 95% CI, 0.31-0.57) but there were no differences in risk for HCC (HR, 1.00; 95% CI, 0.78-1.28). However, entecavir and lamivudine did not have significantly different effects on clinical outcome in 878 pairs of patients without cirrhosis.

CONCLUSIONS

In a retrospective study of 5374 patients with chronic hepatitis B virus infection, entecavir therapy was associated with a significantly lower risk of death or transplantation than lamivudine. However, the drugs did not have different effects on HCC risk.

Comparison of currently available assays for detection of hepatitis B virus DNA in the routine diagnostic laboratory

Infection with the hepatitis B virus (HBV) continues to present diagnostic and therapeutic challenges worldwide. Today, many routine diagnostic laboratories have implemented assays based on molecular techniques for the detection of HBV DNA. However, the standard algorithm for specific diagnosis of HBV infection still relies on serologic testing. Molecular assays are employed for pretreatment evaluation, clinical staging and monitoring of antiviral therapy. Furthermore, molecular methods are essential for identification of mutations in the HBV genome. Although a continuous improvement of assay performance has been observed during recent years, lack of comparability of different molecular assays remains a problem to be resolved in the future. The limited range of linearity when employing conventional PCR will be overcome by using real-time assays.

A 10-year human hepatitis B virus nucleic test external quality assessment in China: continual improvement

BACKGROUND

Remarkable progress has been made in the quality assurance of Hepatitis B virus (HBV) DNA nucleic amplification techniques (NAT) during the past decade. And this report presents a 10-year external quality assessment (EQA) program performed by National Center for Clinical Laboratories in China since 2003.

METHOD

EQA panels were produced using freeze-dried HBV plasma or negative controls and then calibrated against the first International Standard for HBV DNA.

RESULTS

By 2012, total 35,570 qualitative EQA reports and 56,826 quantitative reports have been collected. The overall correct recognition rate in qualitative test increased from 95.15% in 2003 to 97.99% in 2012. The proportion of participants with acceptable quantitative results also rose to 87.99% in 2012 compared with that of 27.53% in 2003. Besides, we observed a satisfactory reproducibility of <5% in all parallel samples. However, some laboratories still had difficulties in exact quantification of some low viral loads, which near to the limits of the dynamic range of the assays.

CONCLUSION

Taking together, current EQA program showed an encouraging improvement of HBV DNA NAT in China. Distributing more challenging samples and increasing the subtypes are still needed in the future.

Medical virology of hepatitis B: how it began and where we are now

Infection with hepatitis B virus (HBV) may lead to acute or chronic hepatitis. HBV infections were previously much more frequent but there are still 240 million chronic HBV carriers today and ca. 620,000 die per year from the late sequelae liver cirrhosis or hepatocellular carcinoma. Hepatitis B was recognized as a disease in ancient times, but its etiologic agent was only recently identified. The first clue in unraveling this mystery was the discovery of an enigmatic serum protein named Australia antigen 50 years ago by Baruch Blumberg. Some years later this was recognized to be the HBV surface antigen (HBsAg). Detection of HBsAg allowed for the first time screening of inapparently infected blood donors for a dangerous pathogen. The need to diagnose clinically silent HBV infections was a strong driving force in the development of modern virus diagnostics. HBsAg was the first infection marker to be assayed with a highly sensitive radio immune assay. HBV itself was among the first viruses to be detected by assay of its DNA genome and IgM antibodies against the HBV core antigen were the first to be selectively detected by the anti-μ capture assay. The cloning and sequencing of the HBV genome in 1978 paved the way to understand the viral life cycle, and allowed development of efficient vaccines and drugs. Today’s hepatitis B vaccine was the first vaccine produced by gene technology. Among the problems that still remain today are the inability to achieve a complete cure of chronic HBV infections, the recognition of occult HBV infections, their potential reactivation and the incomplete protection against escape mutants and heterologous HBV genotypes by HBV vaccines.

Development and evaluation of a calibrator material for nucleic acid-based assays for diagnosing aspergillosis

Twelve laboratories evaluated candidate material for an Aspergillus DNA calibrator. The DNA material was quantified using limiting-dilution analysis; the mean concentration was determined to be 1.73 × 10(10) units/ml. The calibrator can be used to standardize aspergillosis diagnostic assays which detect and/or quantify nucleic acid.

Management of chronic hepatitis B: Canadian Association for the Study of the Liver consensus guidelines

Chronic hepatitis B (CHB) is a dynamic disease that is influenced by host and virological factors. The management of CHB has become more complex with the increasing use of long-term oral nucleos⁄tide analogue antiviral therapies and the availability of novel diagnostic assays. Furthermore, there is often a lack of robust data to guide optimal management such as the selection of therapy, duration of treatment, potential antiviral side effects and the treatment of special populations. In November 2011, the Canadian Liver Foundation and the Canadian Association for the Study of the Liver convened a consensus conference to review the literature and analyze published data, including other international expert guidelines on CHB management. The proceedings of the consensus conference are summarized and provide updated clinical practice guidelines to assist Canadian health care providers in the prevention, diagnosis, assessment and treatment of CHB.