A real-time quantitative polymerase chain reaction method for hepatitis B virus in patients with chronic hepatitis B treated with lamivudine

Next generation digital PCR measurement of hepatitis B virus copy number in formalin-fixed paraffin-embedded hepatocellular carcinoma tissue

BACKGROUND

Hepatocellular carcinoma (HCC) is strongly associated with hepatitis B virus (HBV) infection. False-negative results are common in routine serological tests and quantitative real-time PCR because of HBV surface antigen (HBsAg) variation and low HBV copy number. Droplet digital PCR (ddPCR), a next generation digital PCR, is a novel, sensitive, and specific platform that can be used to improve HBV detection.

METHODS

A total of 131 HCC cases with different tumor stages and clinical features were initially classified with a serological test as HBsAg positive (n = 107) or negative (n = 24) for HBV infection. Next, DNA templates were prepared from the corresponding formalin-fixed paraffin-embedded (FFPE) tissues to determine HBV copy number by ddPCR.

RESULTS

HBV copy numbers, successfully determined for all clinical FFPE tissues (n = 131), ranged from 1.1 to 175.5 copies/μL according to ddPCR. The copy numbers of HBV were positively correlated with tumor-nodes-metastasis (P = 0.008) and Barcelona-Clinic Liver Cancer (P = 0.045) classification. Moreover, serum cholinesterase correlated with hepatitis B viral load (P = 0.006).

CONCLUSIONS

HBV infection is a key factor that influences tumorigenesis in HCC by regulating tumor occurrence and development. ddPCR improves the analytical sensitivity and specificity of measurements in nucleic acids at a single-molecule level and is suitable for HBV detection.

High dose of Lamivudine and resistance in patients with chronic hepatitis B

Background. Lamivudine is the most affordable drug used for chronic hepatitis B and has a high safety profile. With the daily dose of 100 mg there is progressive appearance of resistance to lamivudine therapy. In our study we used 150 mg of lamivudine daily as a standard dose which warrants further exploration for the efficacy of the drug. Aims of the Study. To assess the efficacy of lamivudine 150 mg daily on resistance in patients with chronic hepatitis B. Methods. This retrospective study consists of 53 patients with chronic hepatitis B treated with 150 mg of lamivudine daily. The biochemical and virological response to the treatment were recorded at a 1-year and 2-, 3-, 4-, and 5-year period and time of emergence of resistance to the treatment was noted. Results. The mean age of the patients was 54 years with 80% being males. The resistance to lamivudine 150 mg daily at 1 year and 2, 3, and 5 years was 12.5%, 22.5%, 37.5%, and 60%, respectively, which is much less compared to the standard dose of 100 mg of lamivudine. Conclusions. Lamivudine is safe and a higher dose of 150 mg daily delays the resistance in patients with chronic hepatitis B.

Virologic monitoring of hepatitis B virus therapy in clinical trials and practice: recommendations for a standardized approach

Treatment of chronic hepatitis B virus (HBV) infection is aimed at suppressing viral replication to the lowest possible level, and thereby to halt the progression of liver disease and prevent the onset of complications. Two categories of drugs are used in HBV therapy: the interferons, including standard interferon alfa or pegylated interferon alfa, and specific nucleoside or nucleotide HBV inhibitors that target the reverse-transcriptase function of HBV-DNA polymerase. The reported results of clinical trials have used varying definitions of efficacy, failure, and resistance based on different measures of virologic responses. This article discusses HBV virologic markers and tests, and their optimal use both for planning and reporting clinical trials and in clinical practice.

Review article: Success and failure of nucleoside and nucleotide analogues in chronic hepatitis B

BACKGROUND

Strong suppression of viral replication and normalization of alanine aminotransferase is feasible with nucleos(t)ide analogues. It is estimated viral replication and liver inflammation can be controlled in 90% of patients with chronic hepatitis B with the current available treatments.

AIM

To review the studies currently available on the management of chronic hepatitis B with nucleos(t)ide analogues.

RESULTS

Although very potent, nucleos(t)ide analogues are not effective in every patient. Some factors are known to influence treatment outcome, but many host and viral factors are still unknown. Stopping rules have to be defined to assess treatment efficacy in an early stage and change the regimen. Discontinuation of nucleos(t)ide analogues is often followed by reactivation of HBV. Data on the risk factors for relapse are necessary in order to decide if treatment can be safely discontinued. Another major drawback of nucleos(t)ide analogues is the emergence of resistance. The efficacy of compounds for the treatment of mutant virus and the impact of cross-resistance is largely unknown. The use of combination therapy to prevent resistance looks promising, but has to be proven.

CONCLUSIONS

HBV has become a treatable disease, however much research is needed to optimize treatment for individual patients and treatment failures.

Association between lamivudine sensitivity and the number of substitutions in the reverse transcriptase region of the hepatitis B virus polymerase

This study aimed to identify the viral factors responsible for poor sensitivity to lamivudine (LAM). We analyzed 49 LAM-treated chronic hepatitis B patients infected with hepatitis B virus (HBV) genotype C. Serum HBV DNA reached a level below the detection limit of the sensitive PCR assay in 31 (63.3%) within the first 24 weeks of LAM therapy (good responder group). Of the patients who did not achieve undetectable levels of HBV DNA within 24 weeks (poor responder group), 15 (83.3%) experienced virological breakthrough, whilst only four patients in the good responder group (12.9%) experienced virological breakthrough. Multivariate analysis revealed that failure to achieve a reduction in viral load to undetectable levels within 24 weeks was independently associated with the occurrence of virological breakthrough. Sequence analysis of the HBV genome revealed that point mutations in the precore region (G1896A) and enhancer I (A1287G/C) were observed more frequently in the good responder group than in the poor responder group (P = 0.002 and 0.019 respectively), and the number of substitutions in the reverse transcriptase domain of the polymerase was significantly higher in the good responders than in the poor responders (P = 0.026). In conclusion, determining the sequence of preexisting HBV, especially for enhancer I, the precore region, and the RT domain of the polymerase region, may be useful in predicting sensitivity to LAM therapy.

Future prospectives for the management of chronic hepatitis B

Chronic hepatitis B virus infection affects about 400 million people around the globe and causes approximately one million deaths a year. Since the discovery of interferon-α as a therapeutic option the treatment of hepatitis B has evolved fast and management has become increasingly complicated. The amount of viral replication reflected in the viral load (HBV-DNA) plays an important role in the development of cirrhosis and hepatocellular carcinoma. The current treatment modalities for chronic hepatitis B are immunomodulatory (interferons) and antiviral suppressants (nucleoside and nucleotide analogues) all with their own advantages and limitations. An overview of the treatment efficacy for both immunomodulatory as antiviral compounds is provided in order to provide the clinician insight into the factors influencing treatment outcome. With nucleoside or nucleotide analogues suppression of viral replication by 5-7 log₁₀ is feasible, but not all patients respond to therapy. Known factors influencing treatment outcome are viral load, ALT levels and compliance. Many other factors which might influence treatment are scarcely investigated. Identifying the factors associated with response might result in stopping rules, so treatment could be adapted in an early stage to provide adequate treatment and avoid the development of resistance. The efficacy of compounds for the treatment of mutant virus and the cross-resistance is largely unknown. However, genotypic and phenotypic testing as well as small clinical trials provided some data on efficacy in this population. Discontinuation of nucleoside or nucleotide analogues frequently results in viral relapse; however, some patients have a sustained response. Data on the risk factors for relapse are necessary in order to determine when treatment can be discontinued safely. In conclusion: chronic hepatitis B has become a treatable disease; however, much research is needed to tailor therapy to an individual patient, to predict the sustainability of response and determine the best treatment for those failing treatment.

COBAS AmpliPrep-COBAS TaqMan hepatitis B virus (HBV) test: a novel automated real-time PCR assay for quantification of HBV DNA in plasma

Success in antiviral therapy for chronic hepatitis B is supported by highly sensitive PCR-based assays for hepatitis B virus (HBV) DNA. Nucleic acid extraction from biologic specimens is technically demanding, and reliable PCR results depend on it. The performances of the fully automatic system COBAS AmpliPrep-COBAS TaqMan 48 (CAP-CTM; Roche, Branchburg, NJ) for HBV DNA extraction and real-time PCR quantification were assessed and compared to the endpoint PCR COBAS AMPLICOR HBV monitor (CAHBM; Roche). Analytical evaluation with a proficiency panel showed that CAP-CTM quantitated HBV DNA levels in one single run over a wide dynamic range (7 logs) with a close correlation between expected and observed values (r = 0.976, interassay variability below 5%). Clinical evaluation, as tested with samples from 92 HBsAg-positive patients, demonstrated excellent correlation with CAHBM (r = 0.966, mean difference in quantitation = 0.36 log(10) IU/ml). CAP-CTM detected 10% more viremic patients and longer periods of residual viremia in those on therapy. In lamivudine (LAM)-resistant patients, the reduction of HBV DNA after 12 months of Adefovir (ADF) was higher in the combination (LAM+ADF) schedule than in ADF monotherapy (5.1 logs versus 3.5 logs), suggesting a benefit in continuing LAM. CAP-CTM detected HBV DNA in liver biopsy samples from 15% of HBsAg-negative, anti-HBcAg-positive graft donors with no HBV DNA in plasma. The amount of intrahepatic HBV DNA was significantly lower in occult HBV infection than in overt disease. CAP-CTM can improve the management of HBV infection and the assessment of antiviral therapy and drug resistance, supporting further insights in the emerging area of occult HBV infection.

Early detection and quantification of lamivudine-resistant hepatitis B virus mutants by fluorescent biprobe hybridization assay in lamivudine-treated patients

BACKGROUND

Long-term lamivudine treatment induces the emergence of lamivudine-resistant hepatitis B virus (HBV). The objective of this study was to develop a fluorescent biprobe hybridization (FBH) assay for the detection and quantification of HBV mutants in the clinical course of lamivudine-treated patients and to evaluate its clinical usefulness.

METHODS

We developed an FBH assay to detect mutations in the HBV DNA polymerase gene. The assay's detection sensitivity was determined using a dilution series of wild-type/mutant plasmid DNA. Blood samples obtained from 27 lamivudine-treated patients were analyzed.

RESULTS

Mutant DNA levels as low as 10% of total HBV DNA were detected (sensitivity = 100%, specificity = 80%). HBV mutants were detected in five of the 27 patients during an average follow-up of 20 months after lamivudine administration. In one of the five patients, the YIDD mutant was detected at the initiation of lamivudine treatment, while the remaining four patients were identified as having YIDD mutants within 3 months after beginning lamivudine administration. Of the five patients with an HBV mutant, four developed breakthrough hepatitis more than 10 months after the detection of HBV mutants, following the reappearance or a re-increase of HBV DNA, characterized by a predominance of the mutant. The YIDD mutant was detected in one patient, even when the titer of the serum HBV DNA was below the detection limit of commercially available quantitative polymerase chain reaction.

CONCLUSIONS

The FBH assay is an efficient method for detecting and quantifying HBV mutants, as early as 3 months after lamivudine administration.

Detection of hepatitis B virus genotypes and mutants: current status

Characterization results of the hepatitis B virus (HBV) genome before, during and after antiviral treatment have changed in the last year for a number of reasons. First of all, with the introduction of more nucleoside and nucleotide antiviral therapies, it has become clear that variants or mutants do emerge in time. Viral genomic changes in the HBV polymerase gene can result in a direct antiviral effect, but compensatory mutations can also be identified during prolonged treatment periods. Furthermore, there is an increasing number of reports suggesting that HBV genotypes can be related to, for example, disease progression or the effect of antiviral treatment itself (alpha-interferon or lamivudine). Combined with HBV DNA viral load monitoring, an increase in viral load or a limited reduction during treatment is indicative of genomic changes related to resistance. However, these genomic changes can also be present in the absence of an increase in HBV DNA. Methodologies for the detection of these variants, as well as the determination of genotypes, are rather straightforward. Sequence analysis is time-consuming and expensive, but provides the most information, particularly if not all information on mutations related to antiviral resistance is known. However, the sensitivity of direct sequencing for the presence of minor variant populations is poor, and no mixtures of variant populations are, in general, detected. The ability to detect minor populations and, if possible, even quantify them, gives more insightful information on the dynamic evolution of the virus itself. Antiviral treatment can result in the appearance of more than one population of variants, which can be present for a prolonged period of time, and even remain undetected with current technologies. However, screening specifically for these variant populations before starting treatment for so-called untreated patients (who have received no antiviral treatment for, e.g., 6 months) has already shown that the effects of treatment can be biased. Furthermore, the detection of more dynamic viral populations - including both wild-type and resistant variants - during, but also after therapy, does provide helpful information in the analysis of virological data. Technologies enabling the detection and quantification of these variant populations are presented and discussed.

Real-time PCR in clinical microbiology: applications for routine laboratory testing

Real-time PCR has revolutionized the way clinical microbiology laboratories diagnose many human microbial infections. This testing method combines PCR chemistry with fluorescent probe detection of amplified product in the same reaction vessel. In general, both PCR and amplified product detection are completed in an hour or less, which is considerably faster than conventional PCR detection methods. Real-time PCR assays provide sensitivity and specificity equivalent to that of conventional PCR combined with Southern blot analysis, and since amplification and detection steps are performed in the same closed vessel, the risk of releasing amplified nucleic acids into the environment is negligible. The combination of excellent sensitivity and specificity, low contamination risk, and speed has made real-time PCR technology an appealing alternative to culture- or immunoassay-based testing methods for diagnosing many infectious diseases. This review focuses on the application of real-time PCR in the clinical microbiology laboratory.

Complications in treating chronic hepatitis B in patients with HIV

The management of chronic hepatitis B virus (HBV) poses specific problems in the presence of HIV infection, as therapeutic approaches have to consider both HBV and HIV. There are currently four drugs approved for the treatment of chronic HBV: IFN-alpha, lamivudine, adefovir and entecavir. Furthermore, the dual antiviral activity against HIV and HBV of antiretrovirals such as tenofovir and emtricitabine broadens the armamentarium against HBV in the HIV-coinfected population. Nucleotide analogues adefovir and tenofovir have the advantage of a higher genetic barrier for resistance when compared with the nucleoside analogues lamivudine and emtricitabine. Fortunately, the two families do not share resistance mutations, allowing salvage therapy and the consideration of combination therapy for drug-naive individuals. Although response to IFN-alpha is poorer in HBV/HIV-coinfected patients compared with HBV-monoinfected individuals, the more potent pegylated forms of IFN-alpha have brought new hopes.

Management of patients co-infected with hepatitis B virus and HIV

The management of chronic hepatitis B virus (HBV) infection poses specific problems in the presence of HIV co-infection, since therapeutic approaches have to consider both HBV and HIV infections. There are currently four drugs approved for the treatment of chronic HBV infection (interferon alpha, lamivudine, adefovir, and entecavir); the dual antiviral activity of tenofovir and emtricitabine broadens the armamentarium against HBV in HBV/HIV co-infected patients. Nucleotide analogues--eg, adefovir and tenofovir--have the advantage of a higher genetic barrier to the development of resistance compared with nucleoside analogues--eg, lamivudine and emtricitabine. Fortunately, the two families do not share resistance mutations, allowing salvage therapy and the possibility of combination therapy for drug-naive individuals. Although response to interferon alpha is poorer in HBV/HIV co-infected patients compared with HIV-negative individuals, especially in hepatitis B e antigen-negative HBV infection, the more potent pegylated forms of interferon alpha have brought new hope.

Advances in hepatitis B and C

PURPOSE OF REVIEW

Hepatitis B and C infections are prevalent around the world and a major health burden due to the associated complications of hepatic fibrosis, cirrhosis and hepatocellular carcinoma which occur in the context of chronic infection. Significant advances are being made in assessing and treating infected patients and recent studies are now targeting patients who have failed to respond to previous treatments or who have associated co-morbidities. The purpose of this article to review the recent literature on the subject of hepatitis B and C infections with particular focus on new treatment options, new approaches in patients who have previously failed therapy and in those who have co-morbidity.

RECENT FINDINGS

A large number of studies have been carried out investigating the roles of varying doses, targeting treatment in particular groups and new treatment options in patients infected with hepatitis B and C. Several key findings such as the value of prolonging treatment in patients with genotype 1 hepatitis C infection, the use of pegylated interferon in chronic hepatitis B infection and the emergence of new treatments such as adefovir for resistant hepatitis B infection, as well as treatment of patients co-infected with hepatitis C and human immunodeficiency virus, have dominated the recent literature. Patients in particular groups such as those who have had liver transplantation or who are immunosuppressed have also received added attention.

SUMMARY

Hepatitis B and C infections are the focus of much current attention with particular regard to new and emerging treatment options which are becoming increasingly focused on varying patient groups.

Quantifying anti-HBV effect of targeted ribonuclease by real-time fluorescent PCR

AIM: To quantify the inhibition of HBV replication by targeted ribonuclease by using real-time fluorescent PCR.

METHODS: Targeted ribonuclease was introduced into 2.2.15 cells by liposome-mediated transfection or HIV-TAT mediated protein transduction. Forty-eight hours after the transfection and 24 h after the transduction, supernatants of 2.2.15 cells were collected and HBV DNA in the supernatants was quantified by real-time fluorescent PCR with a commercial kit.

RESULTS: HBV DNA concentrations in the supernatants of 2.2.15 cells transfected or transducted with targeted ribonuclease were 4.9 ± 2.4 × 10⁸ copies/L and 8.3 ± 4.0 × 10⁸ copies/L, respectively. Compared with controls, transfection or transduction of targeted ribonuclease reduced HBV DNA concentration in the supernatants of 2.2.15 cells by 90.4% and 90.1%, respectively (P < 0.05).

CONCLUSION: Targeted ribonuclease can inhibit HBV replication in 2.2.15 cells.

Management of Antiviral Resistance in Patients with Chronic Hepatitis B

A meeting of physicians and scientists involved in the management of chronic hepatitis B (CHB) was held to review current scientific data regarding antiviral resistance in hepatitis B virus (HBV) infection. The goals of the meeting were to describe current treatments for CHB, discuss emerging issues in HBV drug resistance and to delineate patient monitoring, including markers for resistance, during administration of antiviral therapy. The aim of this review article is to provide treating physicians with a framework for the management of CHB in the context of antiviral resistance. Definitions of primary and secondary antiviral treatment failure can be used to aid monitoring and early diagnosis of drug resistance before disease progression occurs as a consequence of viral breakthrough. Primary antiviral treatment failure is defined as failure of a drug to reduce HBV DNA levels by ≥1xlog10 IU/ml within 3 months following initiation of therapy, and secondary antiviral treatment failure as a rebound of HBV replication of ≥1xlog10 IU/ml from nadir in patients with an initial antiviral treatment effect (≥1xlog10 IU/ml decrease in serum HBV DNA). Confirmation of antiviral drug failure can be established by sequencing the HBV DNA polymerase and identifying specific genetic markers of antiviral drug resistance. In addition to virological assays, HBV resistance can be assessed from a clinical perspective including increased serum alanine aminotransferase levels and the development of systemic symptoms or signs of liver failure. Potential strategies to prevent the emergence of resistance and how to manage drug-resistant HBV once it emerges are discussed.