Performance evaluation of cobas HBV real-time PCR assay on Roche cobas 4800 System in comparison with COBAS AmpliPrep/COBAS TaqMan HBV Test

Hepatitis B e antigen loss in adults and children with chronic hepatitis B living in North America: A prospective cohort study

Hepatitis B e antigen (HBeAg) is a soluble viral protein in plasma of patients with hepatitis B virus infection. HBeAg loss is an important first stage of viral antigen clearance. We determined the rate and predictors of HBeAg loss in a North American cohort with chronic hepatitis B viral infection (CHB). Among children and adults with CHB and without HIV, HCV or HDV co-infection enrolled in the Hepatitis B Research Network prospective cohort studies, 819 were HBeAg positive at their first assessment (treatment naïve or >24 weeks since treatment). Of these, 577 (200 children, 377 adults) were followed every 24-48 weeks. HBeAg loss was defined as first HBeAg-negative value; sustained HBeAg loss was defined as ≥2 consecutive HBeAg-negative values ≥24 weeks apart. During a median follow-up of 1.8 years, 164 participants experienced HBeAg loss, a rate of 11.4 (95% CI, 9.8-13.3) per 100 person-years. After adjustment for confounders, HBeAg loss rate was significantly higher in males than females, in older than younger individuals, in Whites or Blacks than Asians, in those with genotype A2 or B versus C, and in those with basal core promoter/pre-core mutations versus wild type. Additionally, during follow-up, an ALT flare and a lower quantitative HBsAg, quantitative HBeAg or HBV DNA level predicted higher rates of HBeAg loss. The majority (88%) with HBeAg loss had sustained HBeAg loss. In conclusion, a number of specific demographic, clinical and viral characteristics impacted rate of HBeAg loss and may prove useful in design and interpretation of future therapeutic studies.

SIX1/EYA1 are novel liver damage biomarkers in chronic hepatitis B and other liver diseases

Background

This study aimed to investigate the clinicopathological significance of sine oculis homeobox homolog 1 (SIX1) and eyes absent 1 (EYA1) in patients with chronic hepatitis B (CHB) and other liver diseases.

Methods

SIX1 and EYA1 levels were detected in human serum and liver tissues by enzyme linked immunosorbent assay (ELISA) and immunofluorescent staining method, respectively.

Results

The serum SIX1 and EYA1 levels in 313 CHB patients were 7.24±0.11 and 25.21±0.51 ng/mL, respectively, and these values were significantly higher than those in 33 healthy controls (2.84±0.15 and 13.11±1.01 ng/mL, respectively; P<0.05). Serum SIX1 and EYA1 levels were also markedly increased in patients with numerous other liver diseases, including liver fibrosis, hepatocellular carcinoma, fatty liver disease, alcoholic liver disease, fulminant hepatic failure, autoimmune liver disease, and hepatitis C, compared to the healthy controls (P<0.05). Dynamic observation of these proteins over time in 35 selected CHB patients revealed that SIX1 and EYA1 serum levels increased over an interval. Immunofluorescent staining revealed that both SIX1 and EYA1 were only expressed in hepatic stellate cells (HSCs), and their increased expression was evident in CHB liver tissue.

Conclusions

SIX1 and EYA1 are novel biomarkers of liver damage in patients of CHB and other liver diseases, with potential clinical utility.

Diagnosis and Monitoring of Hepatitis B Virus Infection Using the Cobas® HBV Test for Use on the Cobas® 4800 System

(1) Background: Sensitive and accurate nucleic acid amplification technologies are now recommended for hepatitis B virus (HBV) DNA detection and quantification in clinical practice to diagnose and monitor hepatitis B infection. The aim of this study was to assess the analytical and clinical performance of the cobas^® HBV Test on the cobas^® 4800 System. (2) Methods: Standard panel and clinical specimens were tested in parallel with three different real-time commercial PCR assays including the cobas ^® HBV Test, the Cobas^® AmpliPrep/Cobas^® TaqMan HBV Test v2.0 and Alinity™ m HBV assay. (3) Results: The specificity of the cobas^® HBV Test was 97.9%. The limit of detection was estimated to be 2.1 IU/mL. Intra-assay and interassay coefficients of variation varied from 0.14% to 1.92% and 2.16% to 12.02%, respectively. HBV DNA levels in patients infected with different HBV genotypes strongly correlated with those measured by the two other commercial comparators assays. (4) Conclusions: The cobas^® HBV Test can be confidently used to detect and accurately quantify HBV DNA in clinical practice as well as in clinical trials with the new anti-HBV drugs currently in development.

FibroScan Detection of Fatty Liver/Liver Fibrosis in 2266 Cases of Chronic Hepatitis B

Background and Aims: FibroScan is used to determine liver stiffness and controlled attenuation parameter (referred to as CAP) scores in patients, including those with chronic hepatitis B (CHB). We used FibroScan to detect the incidence of fatty liver and fibrosis in CHB patients, and to assess the correlation of FibroScan measurements with blood chemistry tests. Methods: CHB patients enrolled in this study were divided independently for three separate analyses (of fibrosis, cirrhosis, and fatty liver) based on FibroScan results. Basic information, blood chemistry test results, liver fibrosis parameters, and FibroScan results were collected. T-tests and Pearson's analyses were used to analyze the correlations between FibroScan liver stiffness measurement/CAP values and liver function, blood fat, uric acid metabolite, fibrosis, and hepatitis B virus load. Results: A total of 2266 CHB patients were enrolled in the study and divided into three groups: non-significant and significant fibrosis; non-cirrhosis and early cirrhosis; and non-fatty and fatty liver. Spearman's statistical analyses showed that liver stiffness measurement or CAP values correlated with sex (r=0.137), age (r=0.119),glutamic-pyruvic transaminase (r=0.082), glutamic-oxaloacetic transaminase (r=-0.172), gamma-glutamyltransferase (r=0.225), albumin (r=0.150), globulin (r=-0.107), total bilirubin (r=-0.132), direct bilirubin (r=-0.145), white blood cell count (r=0.254), hemoglobin (r=0.205), platelets (r=0.206), total cholesterol (r=0.214), high density lipoprotein (r=-0.243), low density lipoprotein (r=0.255), apolipoprotein B (r=0.217), hyaluronic acid (r=-0.069), laminin (r=-0.188), procollagen type IV (r=-0.067)and hepatitis B viral DNA load (r=-0.216). Conclusions: FibroScan is a non-invasive device that can detect the occurrence of fatty liver or liver fibrosis in CHB patients.

Generating timely molecular diagnostic test results: workflow comparison of the cobas® 6800/8800 to Panther

Background: Molecular diagnostic tests for HBV, HCV and HIV-1 and other pathogens are widely used for clinical management. Practical issues related to workflow and labor requirements need to be characterized to inform selection of the most appropriate system. Research design and methods: We compared the workflow of two high-throughput systems: cobas 6800 (Roche) and Panther (Hologic), using average mid-size laboratory test volumes for five different assays (HIV-1, HBV, HCV, HPV or TV, and CT/NG). Results: Set-up time, time to first results, time to last results, and total hands-on time for cobas 6800 was 0.40, 2.47, 7.12, and 0.98 hours, respectively; on the Panther system, these times were 0.75, 2.7, 9.1, and 1.48 hours. Fifty-seven samples had results available at the first time point on cobas 6800 compared to 5 samples on the Panther system. The Panther system required more manual steps including several with potential risks of contamination or error. The number of reagents items required was 5 for cobas 6800 and 40 for the Panther system. Conclusions: Both systems provided a high level of automation. The cobas 6800 platform had shorter start up, time to first result, time to last result and hands-on times than the Panther system.

Age, race and viral genotype are associated with the prevalence of hepatitis B e antigen in children and adults with chronic hepatitis B

Hepatitis B e antigen (HBeAg) is an important serological marker of hepatitis B virus (HBV) infection and is associated with higher levels of viraemia, increased risk of infectivity to others and increased risk of hepatocellular carcinoma. We analysed HBeAg status in a large cohort of adults and children enrolled in Cohort Studies of the Hepatitis B Research Network, long-term natural history studies of chronic HBV infection. A cross-sectional analysis examined factors associated with HBeAg positivity, including demographic and virologic data, across the age spectrum. Among 2241 enrolled participants who met criteria for this analysis, 825 (37%) were seropositive for HBeAg. The prevalence of HBeAg was lower in those with older age, ranging from 85% among those up to 10 years of age to only 12% among those older than 50 years. In addition to age, both race and HBV genotype were independently associated with HBeAg positivity. There was a significant interaction between age and race; the prevalence of HBeAg was significantly higher among Asians > 10-30 years old vs Whites or Blacks who were >10 to 30 years old and those infected with HBV genotype C. Conversely, the presence of the basal core promoter and precore variants was associated with significantly lower prevalence of HBeAg, even when adjusted for age, race and genotype. These data will provide a better understanding of factors associated with seropositivity for HBeAg and may lead to better strategies for preventing HBV infection and broader indications for antiviral therapy.

Analytical performance of four molecular platforms used for HIV-1, HBV and HCV viral load determinations

Background: Viral load (VL) quantification is important for the management of HBV, HCV, and HIV-1-infected patients. Several semi- or fully automated systems and assays are available that can be used to measure VL for these and other targets. Research design and methods: We assessed the accuracy, genotype/subtype inclusivity, and precision of four VL assays for three viral targets: cobas 4800 (Roche), cobas 6800 (Roche), Aptima (Hologic) and VERIS (Beckman), using WHO standards, cell culture supernatants and clinical samples. Results: Most results were close to expected values, except for significant under-quantification of HIV-1 group O, HBV genotype C, and D at high VL, and HCV genotype 3 by Aptima, and of HIV-1 CRF01_AE and group N and HCV genotype 3 by VERIS. Precision was comparable between tests except for VERIS HCV, which showed more variability. Aptima and cobas 6800 results agreed well with each other except HBV VL at lower VL (<10,000 IU/mL) where Aptima results tended to be higher. Conclusions: Results from different VL assays may not always agree in certain subsets of patients. Clinicians should we aware of these findings when making treatment decisions.

Amplification chemistries in clinical virology

Molecular diagnostic methods have evolved and matured considerably over the last several decades and are constantly being evaluated and adopted by clinical laboratories for the identification of infectious pathogens. Advancement in other technologies such as fluorescence, electronics, instrumentation, automation, and sensors have made the overall diagnostic process more accurate, sensitive, and rapid. Nucleic acid based detection procedures, which rely on the fundamental principles of DNA replication have emerged as a popular and standard diagnostic method, and several commercial assays are currently available based on different nucleic acid amplification techniques. This review focuses on the major amplification chemistries that are used for developing commercial assays and discusses their application in the clinical virology laboratory.

Performance characteristics of a fast real-time PCR assay for hepatitis B virus DNA quantification

Detection of hepatitis B virus (HBV) DNA is particularly important for detection of early acute and of occult HBV infection. On the other hand, HBV DNA detection and quantification are essential to diagnose and treat chronic HBV infection. In this study, we evaluated the performance of the real-time PCR SUMASIGNAL VHB (un paso) (Immunoassay Center, Cuba). The clinical and analytical specificity of the assay was 100%. Intra-assay and inter-assay coefficients of variation ranged from 0.50 to 2.53% and from 1.23 to 3.03%, respectively. A strong correlation (r=0.926; P<0.001) with the COBAS^® AmpliPrep/COBAS^® TaqMan^® HBV Test, v2.0 (Roche Molecular Systems, Inc.) was obtained. The limit of detection using the third WHO international standard for HBV DNA was 377.47 IU/mL. The test was able to detect the most prevalent HBV genotypes (A-G) equally well. In conclusion, the SUMASIGNAL VHB (un paso) is a sensitive, specific, precise and accurate assay for the quantification of serum and plasma HBV DNA. Thus, this simple and fast real-time PCR test can be used as an aid in diagnosing an HBV infection and monitoring drug efficacy.

Viral Biomarkers in Chronic HBeAg Negative HBV Infection

Viral biomarkers are important tools for monitoring chronic hepatitis B virus (HBV) hepatitis B early antigen (HBeAg) negative infection, both in its natural course as well as during and after treatment. The biomarkers consist of antibodies against viral epitopes, viral proteins, and molecular surrogate markers of the quantity and transcriptional activity of the stable episomal HBV covalently closed circular DNA (cccDNA) which is located in the nuclei of the infected hepatocytes. HBV deoxyribonucleic acid (DNA) or else viral load measurement in plasma or serum is a marker of HBV replication of major clinical importance. HBV DNA is used for staging and treatment monitoring as described in international scientific guidelines. Quantification of HBV antigens, mainly hepatitis B surface antigen (HBsAg) as well as Hepatitis B core related antigen (HBcrAg), play an important yet secondary role, especially in cases of low or undetectable HBV DNA and has been evaluated for the classification of the inactive carrier state, as a predictor of subsequent HBsAg clearance, treatment outcome, and development of hepatocellular carcinoma (HCC). The measurement of the replicative intermediate HBV RNA in serum is currently evaluated and may also prove to be a significant biomarker particularly in patients treated with nucleot(s)ide analogs. This review focuses on the viral biomarkers mentioned above and their role in HBV, HBeAg negative, infection.