Comparison of the second-generation digene hybrid capture assay with the branched-DNA assay for measurement of hepatitis B virus DNA in serum

Introduction of an automated system for the diagnosis and quantification of hepatitis B and hepatitis C viruses

Hepatitis B virus (HBV) and Hepatitis C virus (HCV) infections pose major public health problems because of their prevalence worldwide. Consequently, screening for these infections is an important part of routine laboratory activity. Serological and molecular markers are key elements in diagnosis, prognosis and treatment monitoring for HBV and HCV infections. Today, automated chemiluminescence immunoassay (CLIA) analyzers are widely used for virological diagnosis, particularly in high-volume clinical laboratories. Molecular biology techniques are routinely used to detect and quantify viral genomes as well as to analyze their sequence; in order to determine their genotype and detect resistance to antiviral drugs. Real-time PCR, which provides high sensitivity and a broad dynamic range, has gradually replaced other signal and target amplification technologies for the quantification and detection of nucleic acid. The next-generation DNA sequencing techniques are still restricted to research laboratories.The serological and molecular marker methods available for HBV and HCV are discussed in this article, along with their utility and limitations for use in Chronic Hepatitis B (CHB) diagnosis and monitoring.

Molecular methods in the diagnosis and management of chronic hepatitis B

Chronic hepatitis B (CHB) infection remains a major global problem but the recent advances in molecular methods have revolutionized the diagnosis and management of CHB. Hepatitis B virus (HBV) DNA quantitation is the most useful molecular marker for the diagnosis and management of CHB. There is increasing evidence that the clinical outcome and efficacy of antiviral therapy for CHB could vary with the infecting HBV genotype, core promoter and precore mutations. Early identification of drug resistance is imperative in the management of CHB. The molecular methods for HBV DNA quantitation, HBV genotyping, the identification of mutants, genotypic and phenotypic methods for monitoring drug resistance and their utility and limitations for use in the diagnosis and monitoring of CHB are discussed in this article.

A review of the one-year incidence of resistance to lamivudine in the treatment of chronic hepatitis B : Lamivudine resistance

PURPOSE

The development of antiviral resistance is a recognized challenge to successful treatment of chronic hepatitis B (CHB), but it has been difficult to establish an accurate estimate of its incidence due to a number of factors: (a) lack of an accepted definition of antiviral resistance; (b) lack of a standardized assay to assess resistance; and (c) lack of consensus on patient selection criteria for resistance testing. Lamivudine, an effective and well-established antiviral agent, has been reported to show one-year resistance rates in CHB ranging from 6% to 32%, but methodologies used to calculate these rates vary considerably. This article reviews the clinical, statistical, and laboratory methodologies of clinical studies reporting one-year rates of antiviral resistance to lamivudine in CHB.

METHODS

Studies reporting one-year resistance rates to lamivudine in CHB were analyzed for methodologic differences and their influence on reported resistance rates.

RESULTS

Studies using only a genotypic definition of resistance reported one-year rates ranging from 14% to 32%. Studies assessing genotypic resistance in patients with evidence of virologic breakthrough reported much lower one-year resistance rates of 6.4-15.4%.

CONCLUSIONS

It is important when comparing resistance rates to antiviral drugs in CHB to consider the methodology and definition of resistance used because this can dramatically influence the results.

A review of the one-year incidence of resistance to lamivudine in the treatment of chronic hepatitis B : Lamivudine resistance

PURPOSE

The development of antiviral resistance is a recognized challenge to successful treatment of chronic hepatitis B (CHB), but it has been difficult to establish an accurate estimate of its incidence due to a number of factors: (a) lack of an accepted definition of antiviral resistance; (b) lack of a standardized assay to assess resistance; and (c) lack of consensus on patient selection criteria for resistance testing. Lamivudine, an effective and well-established antiviral agent, has been reported to show one-year resistance rates in CHB ranging from 6% to 32%, but methodologies used to calculate these rates vary considerably. This article reviews the clinical, statistical, and laboratory methodologies of clinical studies reporting one-year rates of antiviral resistance to lamivudine in CHB.

METHODS

Studies reporting one-year resistance rates to lamivudine in CHB were analyzed for methodologic differences and their influence on reported resistance rates.

RESULTS

Studies using only a genotypic definition of resistance reported one-year rates ranging from 14% to 32%. Studies assessing genotypic resistance in patients with evidence of virologic breakthrough reported much lower one-year resistance rates of 6.4-15.4%.

CONCLUSIONS

It is important when comparing resistance rates to antiviral drugs in CHB to consider the methodology and definition of resistance used because this can dramatically influence the results.

Tenofovir (TDF) has stronger antiviral effect than adefovir (ADV) against lamivudine (LAM)-resistant hepatitis B virus (HBV)

OBJECTIVES

We retrospectively compared the antiviral effect of tenofovir disoproxil fumarate (TDF) with that of adefovir dipivoxil (ADV) for patients with chronic hepatitis B (CHB) who developed resistance to lamivudine (LAM).

MATERIALS AND METHODS

One hundred nine patients (86 males), all Asian-American except 1 Caucasian male, with LAM resistance received TDF or ADV. HBV DNA levels were measured every 3 months. The HBeAg loss and ALT normalization were assessed at 12 months on therapy.

RESULTS

Forty-four patients (37 males) received TDF (12 with LAM) and 65 (49 males) received ADV (18 with LAM). Median ages (years) for TDF and ADV were 49 (32-68) and 45 (22-68), respectively. Median duration of therapy was 13 months (6-38) and 17 months (6-34) for the TDF and ADV groups. Baseline HBV DNA levels (log(10) copies/ml) were 6.2 +/- 1.7 for the TDF and 6.5 +/- 1.6 for ADV groups. Baseline ALT (IU/l) levels were 77.0 +/- 86.0 and 100 +/- 195 for the TDF and ADV (P = 0.46) groups, respectively. At 12 months, mean levels of log(10) HBV DNA were 1.5 +/- 1.0 and 4.3 +/- 2.2 for TDF and ADV (P = 0.01). HBeAg loss and ALT normalization at 12 months showed no differences. Using a single factor, ANOVA (2-tailed P value), 4 groups, TDF (n = 32), TDF + LAM (12), ADV (47), and ADV + LAM (18), were compared. HBV DNA reduction at 12 months was the greatest for TDF + LAM (P < 0.001).

CONCLUSIONS

Our results suggest that for LAM-resistant HBV, TDF, alone or combined with LAM exerts greater viral reduction than ADV. However, no difference in HBeAg loss was observed. It appears that stronger HBV DNA reduction may not necessarily accelerate HBeAg loss.

Comparison of VERSANT Hepatitis B virus DNA 3.0 Assay with Digene Hybrid Capture II Hepatitis B virus DNA test in relation to clinical status of Hepatitis B virus

BACKGROUND

Some differences exist among various Hepatitis B virus (HBV) DNA quantification assays due to lack of standardization and besides clinical usefulness has not been firmly elucidated in Korean HBV patients.

METHODS

We compared Bayer VERSANT HBV DNA 3.0 Assay (VERSANT 3.0) with Digene Hybrid Capture II HBV DNA Test (HC-II) according to HBeAg status and ALT levels in 232 HBV-infected Korean patients. One hundred and seventeen sera with undetectable DNA levels by HC-II were further analyzed by Real-Q HBV quantification assay (BioSewoom).

RESULTS

Although VERSANT 3.0 and HC-II showed an excellent correlation (r=0.9739), the results (copies/mL) by VERSANT 3.0 were 0.45 log(10) higher than those by HC-II. HBV DNA levels were higher in HBeAg-positive group than in HBeAg-negative group (P=0.002), and in abnormal ALT group than in normal ALT group (P<0.0001). The detection rate of HBV DNA by VERSANT 3.0 was lower in HBeAg-negative and normal ALT group (n=68) than in HBeAg-positive or abnormal ALT group (n=164) (35.3% vs 89.6%, P<0.0001). Fifty two sera out of 61 sera with undetectable DNA by VERSANT 3.0 were measurable by Real-Q with mean value of 3.26 log(10) copies/mL.

CONCLUSIONS

VERSANT 3.0 and HC-II showed an excellent correlation, but a little difference (0.45 log10) existed. VERSANT 3.0 effectively measured clinically relevant HBV DNA levels in most HBV-infected patients in Korea. However, more sensitive assays are needed for patients with negative HBeAg and normal ALT to see the low copies of HBV DNA levels.

Antigen-induced regulatory T cells in HBV chronically infected patients

T cell response against HBV is vigorous in patients with acute hepatitis who clear the virus, whereas it is weak and narrowly focused in patients with chronic disease. We report that following incubation with HBcAg, a population of CD4+FoxP3+ cells expressing phenotypic markers of both natural and induced Tregs, can be antigen-induced from peripheral mononuclear cells. Conversely, naive and naturally immune subjects did not increase CD4+FoxP3+ Tregs following stimulation with HBcAg, supporting the idea that natural Tregs are able to respond specifically to HBV antigen. Furthermore, increased frequencies of antigen-induced CD4+FoxP3+IL-10+ Tregs correlated with viral load, suggesting that antigen-induced Tregs could contribute to an inadequate response against the virus, leading to chronic infection and support the view that specific natural Tregs may be implicated in host immune tolerance during HBV infection.

Viral nephropathy

Viral infections can cause many glomerular diseases. The diagnostic criteria for virus-related nephropathy include detailed clinical and laboratory data, and tissue molecular analysis. Several mechanisms are involved in the pathogenesis of virus-related nephropathy, including tropism of the virus in the kidney, induction of abnormal immune complexes, direct cytopathogenic effects, and multiorgan failure. Hepatitis B virus is associated with membranous nephropathy and mesangiocapillary glomerulonephritis in endemic areas. Hepatitis C virus causes various forms of glomerulonephritis, including cryoglobulinemia-mediated glomerulonephritis. Infection with HIV is associated with a collapsing focal segmental glomerulosclerosis, a distinctive disease that affects mainly Africans and African Americans. In the course of HIV infection, other types of immune complex glomerulonephritis can occur, most frequently in whites. Recent reports indicate a role for parvovirus B19 in 'idiopathic' collapsing focal segmental glomerulosclerosis. Both hantaviruses, and coronaviruses associated with severe acute respiratory syndrome, can lead to acute renal failure. Renal biopsy followed by appropriate serological and molecular testing is essential for defining virus-related glomerular lesions and guiding prognostic and therapeutic evaluation.

Lamivudine in hepatitis B-associated membranous nephropathy

BACKGROUND

Although lamivudine is effective for treatment of chronic hepatitis B (HBV) infection, its potential therapeutic impact on HBV-related membranous nephropathy (MN) in adults has not been characterized.

METHODS

We treated 10 HBsAg-positive patients with biopsy-proven MN, elevated serum alanine aminotransferase (ALT), and HBV-DNAemia (group 1), and compared their clinical course with 12 patients diagnosed to have HBV infection, elevated serum ALT, and MN in the pre-lamivudine era (group 2).

RESULTS

Baseline demographic and clinical parameters were not different between the 2 groups. In group 1, lamivudine treatment was associated with significant reduction in proteinuria, increase in serum albumin, normalization of ALT levels, and disappearance of circulating HBV-DNA during the first year. Four (40%) and 6 (60%) patients went into complete remission (proteinuria <0.3 g/d) at 6 and 12 months, respectively. In group 2, significant proteinuria persisted during the first year. One (8.3%) and 3 (25%) patients went into remission. Cumulative 3-year renal survival [using end-stage renal disease (ESRD) as primary end point] was 100% in group 1 and 58% in group 2 (P= 0.024, log rank test). Blood pressure control reached the target of below 130/85 mm Hg in both groups. Lamivudine was well tolerated and not associated with any adverse events. Hepatic decompensation or malignancy was not observed during follow-up in both groups.

CONCLUSION

HBV-related MN leads to ESRD in a significant proportion of patients before the advent of antiviral therapy. Lamivudine treatment improves renal outcome in HBV carriers with MN and evidence of liver disease.

Evaluation of the COBAS amplicor HBV monitor assay and comparison with the ultrasensitive HBV hybrid capture 2 assay for quantification of hepatitis B virus DNA

Performance characteristics of the COBAS Amplicor HBV Monitor test (Roche Diagnostics), which measures hepatitis B virus (HBV) DNA quantitatively, were evaluated and compared with the Ultrasensitive HBV Hybrid Capture 2 (HC2; Digene Corporation) assay. Linearity and within-run precision were assessed for both methods by using eight HBV DNA-positive samples serially diluted to obtain a range of <100 to 500,000 HBV DNA copies/ml and run in triplicate. Agreement between the methods was studied with 100 clinical samples. HC2 assay performance near the limit of detection was investigated through repeat testing of 149 samples with HC2 and testing of 37 samples with HC2 results of <4,700 HBV DNA copies/ml by Amplicor assay and a qualitative PCR assay. The linearity experiment for Amplicor had regression of observed values compared to expected values (y = 1.073x - 0.247; R(2) = 0.993, n = 32; for HC2, y = 0.855x + 0.759, R(2) = 0.729, n = 18). Within-run standard deviation of log HBV DNA copies/ml ranged from 0.003 to 0.348 (Amplicor) and 0.027 to 0.253 (HC2). Agreement assessed by Deming regression was poor [Amplicor = 1.197(HC2) - 0.961; R(2) = 0.799, standard error of the estimate (SEE) = 0.710, n = 94]. Near the lower limit of detection, 32 of 149 repeat HC2 results were <4,700 HBV DNA copies/ml. Of the 37 samples with HC2 results of <4,700 HBV DNA copies/ml, HBV DNA was not detected in 15 samples, while HBV DNA was detected by at least one PCR method in 12 samples. Amplicor is linear from 200 to 200,000 HBV DNA copies/ml with undiluted samples, and this range can be expanded through dilution. Inconsistent HC2 results near the limit of detection justify use of a grey zone.

Quantification and genotyping of hepatitis B virus in a single reaction by real-time PCR and melting curve analysis

BACKGROUND/AIMS

Both viral titer and genotype of hepatitis B virus (HBV) play critical roles in determining clinical outcome and response to antiviral treatment in hepatitis B patients. In this study, a method was developed to determine both parameters in a single-tube reaction.

METHODS

The method contains two consecutive steps, the first step used real-time PCR for quantification and second step used melting curve analysis for genotyping. For accurate quantification, the PCR primers and hybridization probes were selected from highly conserved regions to ensure the equivalent amplification and hybridization of all genotypes of HBVs. Within the sensor probe there exists signature single nucleotide polymorphisms (SNPs), which could effectively differentiate different HBV genotypes by showing different melting temperatures.

RESULTS

The quantification results showed great consistency with the commercial assays in linear range from 10(2) to 10(11) copies/ml. By comparison with the traditional restriction fragment length polymorphism (RFLP) methods, 99% of samples were accurately genotyped by current assay, and with a higher detection rate. In addition, this method can detect mixed HBV infections.

CONCLUSIONS

Currently, this methodology can be applied to areas prevalent with HBV genotypes B and C, providing an efficient alternative for clinical diagnosis and large-scaled longitudinal studies.

Clinical evaluation of the digene hybrid capture II test and the COBAS AMPLICOR monitor test for determination of hepatitis B virus DNA levels

The measurement of hepatitis B virus (HBV) DNA is important for the assessment of liver disease and treatment efficacy. Most commercially available assays for the determination of HBV DNA levels have limited linear ranges. This study was performed to evaluate the clinical performance of the Digene Hybrid Capture II (Digene HC II assay) and the COBAS AMPLICOR Monitor test (COBAS-AM assay), with special emphasis on anti-HBV e antigen (HBeAg)-positive patients with low HBV DNA levels. A total of 425 Chinese patients with chronic hepatitis B were recruited. A total of 107 patients were HBeAg positive, and 318 patients were HBeAg negative. The Digene HC II assay and the COBAS-AM assay had similar intra-assay and interassay variabilities. A total of 264 patients (62.1%) had HBV DNA levels undetectable by the Digene HC II assay, and 47 patients (11.1%) had HBV DNA levels undetectable by the COBAS-AM assay (P < 0.001). For the 161 patients with HBV DNA levels detectable by the Digene HC II assay, the HBV DNA levels obtained by the Digene HC II assay and by the COBAS-AM assay showed an excellent correlation (r = 0.95; P < 0.001). The linear ranges of the Digene HC II assay and the COBAS-AM assay marginally overlapped. Before HBV DNA levels could be determined by the COBAS-AM assay, predilution had to be performed for 158 of 161 patients (98.1%) with HBV DNA levels detectable by the Digene HC II assay and for 10 of 264 patients (3.8%) with HBV DNA levels undetectable by the Digene HC II assay. The cost for assaying each serum sample by using different strategies was calculated. The COBAS-AM assay was more sensitive than the Digene HC II assay and more suitable for monitoring low levels of HBV viremia.

Prospective study on lamivudine-resistant hepatitis B in renal allograft recipients

The natural history of lamivudine-resistant hepatitis B virus (HBV) infection in renal transplant recipients (RTx) is unclear, despite its increasing incidence. Twenty-nine HBsAg-positive RTx with rising HBV DNA received lamivudine therapy. The course of lamivudine-resistant HBV infection was studied prospectively. During 68.7 +/- 12.5 months of follow-up, 14 (48.3%) patients developed lamivudine resistance, at 10-35 months (mean 16.9 +/- 7.0). All showed mutant sequences at codons 552 and 528 of the YMDD motif, while 13 patients demonstrated wild-type sequence at codon 555. Lamivudine resistance was unrelated to patient demographics, HBeAg status/sero-conversion, or genotype. Following resistance, HBV DNA and alanine aminotransferase showed an initial increase followed by spontaneous gradual reduction. The subsequent peak HBV DNA was lower (1.26 +/- 1.09 x 10(9) vs. 6.26 +/- 12.23 x 10(9) copies/mL, p = 0.011), while that of alanine aminotransferase was higher (196 +/- 117 vs. 77 +/- 47 imicro/l, p = 0.005), compared with pretreatment levels. Post-resistance hepatitic flare occurred in 11 (78.6%) patients. This was transient in four (36.4%), but became chronic in six (54.5%) patients. Decompensation was noted in one patient during this flare, but all survived. We conclude that drug resistance is prevalent in lamivudine-treated RTx. Despite a lower ensuing peak viremia compared with baseline, hepatitic flare is common. While most patients have spontaneous resolution, a minority may develop potentially fatal decompensation during the preceding exacerbation.

Combination therapy with lamivudine and famciclovir for chronic hepatitis B infection

BACKGROUND & AIMS

Lamivudine suppresses hepatitis B replication, but drug-resistant mutants emerge with long-term therapy. In vitro data suggest that lamivudine and famciclovir might synergistically inhibit hepadnaviral replication. We reviewed our experience with lamivudine and famciclovir in 24 patients with chronic hepatitis B infection.

METHODS

Patients with chronic hepatitis B infection and detectable HBV DNA received lamivudine and famciclovir combination therapy. The primary end point was HBV DNA suppression at week 48. Follow-up was reviewed for those who remained on combination therapy beyond the first 48 weeks.

RESULTS

Thirteen treatment-naïve HBeAg-positive subjects received 48 weeks of therapy; all had undetectable HBV DNA levels (less than 2.5 pg/mL) at week 48. Three patients underwent HBeAg seroconversion at week 48 and discontinued therapy. Ten patients remained on combination therapy; 3 developed YMDD (tyrosine-methionine-aspartate-aspartate) mutations at year 2, although HBV DNA levels remained below 2.5 pg/mL at a mean of 39 months. A second heterogeneous group of 5 subjects including interferon therapy failures and those with HBeAg-negative infection also received 48 weeks of combination therapy, with 1 subject developing redetection of HBV DNA by week 48. YMDD mutations were noted in the other 4 subjects at year 2, although just 1 subject had HBV DNA greater than 2.5 pg/mL at 39 months of therapy.

CONCLUSIONS

In this small pilot study, 48 weeks of therapy with lamivudine and famciclovir was effective in suppressing HBV replication. A randomized controlled trial is required to define the role of combination therapy with lamivudine and famciclovir in delaying the clinical emergence of resistant strains.

Clinical evaluation of the COBAS Amplicor HBV monitor test for measuring serum HBV DNA and comparison with the Quantiplex branched DNA signal amplification assay in Taiwan

AIMS

To evaluate the performance characteristics and clinical usefulness of the COBAS Amplicor HBV monitor (COBAS-AM) test in Taiwan and to examine its correlation with the Quantiplex branched DNA signal amplification (bDNA) assay for measuring serum hepatitis B virus (HBV) DNA concentrations.

METHODS

HBV DNA was measured by the COBAS-AM test in 149 sera from chronic HBV infected patients that had previously been analysed by the bDNA assay.

RESULTS

The COBAS-AM test showed good reproducibility, with acceptable intra-assay and interassay coefficients of variation (1.6% and 0.9%, respectively) and good linearity (r2=0.98). The overall sensitivity of the COBAS-AM test was significantly higher than that of the bDNA assay (95.3% v 83.2%): 69.6% of samples with HBV DNA below the detection limit of the bDNA assay could be measured by the COBAS-AM test. There was a significant correlation between the results of the two assays (r=0.901; p<0.0001). On average, the results derived from the COBAS-AM test were 0.55 log lower than those of the bDNA assay. HBV DNA concentrations were significantly higher among HBV e antigen (HBeAg) positive patients than negative ones, and higher among patients with abnormal alanine aminotransferase (ALT) concentrations than those with normal ALT concentrations (p=0.0003).

CONCLUSIONS

The COBAS-AM assay, more sensitive in HBeAg negative samples than the bDNA assay, can effectively measure HBV DNA concentrations in Taiwanese patients. HBV DNA values measured by the COBAS-AM test and bDNA assay correlate significantly.

Hepatitis B core antigen is a potent inductor of interleukin-18 in peripheral blood mononuclear cells of healthy controls and patients with hepatitis B infection

Clearance of hepatitis B virus infection (HBV) infection implies a polyclonal vigorous T-helper 1 (Th1) and cytotoxic T-lymphocyte (CTL) response. Interleukin-18 (IL-18), a monokine that shares functional abilities with IL-12, is a potent inductor of interferon-gamma (IFN-gamma) by Th1 and natural killer (NK) cells. However, the role and regulation in HBV infection of IFN-gamma have not been defined. This study therefore sought to determine hepatitis B core antigen (HBcAg)-mediated regulation of IL-18 production in peripheral blood mononuclear cells (PBMCs) from healthy controls (HC) and patients with chronic hepatitis B (CHB) or acute hepatitis B (AHB); 31 HC, 27 patients with CHB and 8 patients with AHB infection were included in the study. HBcAg-mediated induction of IL-18 was determined by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and specific enzyme-linked immunosorbent assay (ELISA). HBcAg induced IL-18 gene transcription and dose-dependent secretion of mature IL-18 protein in HC, CHB, and AHB. HBcAg-dependent IL-18 levels were abrogated by inhibition of Caspase-1, but not by blockade of CD40-CD154 interaction. Serum levels of IFN-gamma correlated inversely with viremia in patients with CHB (rho = - 0.54, P < 0.05), but not with serum levels of IL-12 or IL-18. Interestingly, in PBMCs of HBeAg-negative patients, HBcAg induced significantly higher amounts of IL-18 than in those of HBeAg-positive patients. A variant, lacking the histone-like arginine-rich domain, did not induce IL-18 in either HC or CHB in vitro. Taken together, these results indicate that HBcAg induces IL-18 secretion by induction of Caspase-1. Differential regulation in HBeAg-negative and positive patients suggests an important role of IL-18 in CHB infection.

Rapid quantification of hepatitis B virus DNA by real-time PCR using fluorescent hybridization probes

A highly sensitive and rapid assay has been developed to quantify hepatitis B virus (HBV) DNA, based on the fluorescence resonance energy transfer principle and real-time PCR, using the LightCycler and a pair of specific fluorescent hybridization probes. This LightCycler real-time PCR assay (LC-PCR) detected HBV DNA in a linear range from 10(1) to 10(8) copies per reaction (250-2.5 x 10(9) copies ml(-1)), with a rapid PCR cycling time of 35 min. The assay was validated with two EUROHEP HBV DNA standards (ad and ay subtypes) and exhibited low intra-assay (< 6 %) and inter-assay (< 16 %) variation for both subtypes over the complete range of 7 orders of magnitude. The assay was evaluated clinically using serum samples from 120 HBsAg(+) individuals and 45 healthy controls who were negative for both HBsAg and anti-HBc. Levels of HBV DNA were measured in these samples using both the LC-PCR and Digene Hybrid Capture II HBV DNA (HCII) assays. The prevalence rates for HBV DNA in the HBsAg(+) serum samples were respectively 95 % (114/120) and 56 % (67/120) by LC-PCR and HCII (P < 0.01). All 67 HCII-positive samples tested positive with LC-PCR, while the 47 discordant samples showed low levels of HBV DNA (down to 265 copies ml(-1)), detectable only by the more sensitive LC-PCR assay. Levels of HBV DNA as measured by the two assays showed good correlation (r = 0.902; P < 0.001). The level of HBV DNA was significantly higher in HBeAg(+) than anti-HBe(+) samples (median 1.5 x 10(7) vs 4.6 x 10(4) copies ml(-1); P < 0.01). It is concluded that this LC-PCR assay is clinically useful for the rapid, sensitive and accurate measurement of HBV DNA.

Detection of hepatitis B virus DNA in sera from patients with chronic hepatitis B virus infection by DNA microarray method

We have developed a sensitive and quantitative assay using a DNA microarray for the detection of hepatitis B virus (HBV) DNA in serum. Fluorescently labeled target cDNA prepared from cloned HBV DNA or serum HBV DNA was hybridized to capture DNA on a slide. A linear relationship was obtained between the intensities of the array spot and the amount of the cloned or serum HBV DNA, indicating the quantitative accuracy of this assay system. In addition, there was a significant correlation between the number of molecules of serum HBV DNA determined by the DNA microarray and that determined by a branched-DNA assay (n = 21, r = 0.89). Given these results, we conclude that the DNA microarray assay system may be useful as a diagnostic technique in the clinical laboratory.

Molecular diagnosis of viral hepatitis

Molecular biology-based assays are invaluable tools for the management of chronic viral hepatitis. They can be used to test blood donations, diagnose active infection, help to establish the prognosis, guide treatment decisions, and assess the virological response to therapy. This article reviews current molecular biology-based techniques and assays, and their practical use in the management of hepatitis B and C virus infection.

Efficacy of famciclovir in the treatment of lamivudine resistance related to an atypical hepatitis B virus mutant

Reactivation of chronic hepatitis B virus (HBV) infection is a major cause of morbidity and mortality after renal transplantation. Although lamivudine is an effective treatment for chronic hepatitis B, the development of drug resistance due to mutations in the tyrosine-methionine-aspartate-aspartate (YMDD) motif is a major concern, especially in immunosuppressed patients who require prolonged therapy. Treatment with famciclovir has not been effective in the majority of patients who developed lamivudine resistance due to methionine-to-valine mutation at position 550, because this mutation has been uniformly associated with leucine-to-methionine mutation at position 526, a mutation that is associated with resistance to famciclovir. We describe a renal transplant recipient with an uncommon lamivudine-resistant HBV variant, in which methionine-to-valine/isoleucine mutation at position 550 was associated with wild-type sequence at position 526. The severe hepatitic flare consequent to the lamivudine resistance in this patient was successfully treated with famciclovir, indicating that both M550V and M550I mutants with preserved wild-type sequence at position 526 of HBV reverse transcriptase are susceptible to famciclovir. Our experience shows that famciclovir can be useful in selected patients with otherwise potentially fatal hepatitic flares related to lamivudine resistance, and that analysis of mutations in the HBV variant can be helpful in the choice of antiviral therapy.

Aggressive hepatocellular carcinoma complicating pregnancy after autologous bone marrow transplantation for non-Hodgkin's lymphoma

In the Asia-Pacific region, autologous and allogeneic bone marrow transplantation (BMT) in patients infected with the hepatitis B virus (HBV) may be complicated by fatal hepatic failure due to viral reactivation. Survivors may suffer from accelerated hepatitis and cirrhosis. We report the first case of hepatocellular carcinoma (HCC) after autologous BMT for mediastinal B cell lymphoma. The tumor developed rampantly during a planned pregnancy 5 years after BMT. Less than 40 cases of HCC complicating pregnancy have been reported, and outcome is invariably poor. Immunosuppression and HBV reactivation after autologous BMT, as well as immune tolerance and hormonal changes associated with pregnancy may contribute to the rapid tumor growth. Biochemical and radiological surveillance for HCC should be strengthened in HBV carriers after BMT, especially in patients with the histology of chronic liver disease, or biochemical/ virological evidence of increased HBV activity.

Quantitative detection of hepatitis B virus DNA in serum by a new rapid real-time fluorescence PCR assay

A sensitive and accurate HBV DNA quantification assay is essential for monitoring hepatitis B virus (HBV) replication. This study evaluated a real-time PCR method performed in the LightCycler analyser for quantitative HBV DNA assay. HBV DNA results with this method were compared with those obtained using a branched-chain DNA (bDNA) solution hybridization assay. Real-time PCR was performed using two adjacent fluorescently labelled probes and primers corresponding to the HBV core gene. The same standard employed in the bDNA assay was used for calibration. Serum samples came from 193 HBV surface antigen (HBsAg)-positive patients (34 HBV e antigen (HBeAg)-positive and 93 with antibody to HBeAg (anti-HBe)), and 66 asymptomatic HBV carriers. In addition, we analysed serum samples from 8 anti-HBe-positive patients who had been receiving lamivudine treatment for more than three years. A linear standard curve was seen in the range from 10(3) to 10(8) copies/mL. In the reproducibility analysis, intra-assay coefficient of variation (CVs) at two known HBV DNA concentrations were 4% and 2% and interassay CVs were 6% and 4%. The median of serum HBV DNA by real-time PCR was 9.2 x 10(8) copies/mL in HBeAg-positive patients with persistently elevated alanine aminotransferase (ALT) levels, 1.3 x 10(7) copies/mL in anti-HBe-positive cases with persistently elevated ALT levels, 3.7 x 10(4) copies/mL in anti-HBe-positive patients with fluctuating ALT levels and 10(4) copies/mL in asymptomatic HBV carriers. The differences in HBV DNA levels among the various groups studied were statistically significant (P < 0.05). The cut-off between chronic hepatitis patients and asymptomatic carriers was found to be at a serum HBV DNA concentration of 5 x 10(4) copies/mL. Of the 109 serum samples with a viral load < 7.5 x 10(5) (negative by bDNA assay) 44 (40%) were positive by real-time PCR: 24 (56%) chronic hepatitis and 20 (33%) asymptomatic carriers. There was a positive association between HBV DNA levels determined by real-time PCR and ALT levels (P < 0.05), which was not observed with the bDNA assay for HBV DNA quantification. At 12 months of lamivudine treatment, 6 patients (75%) showed HBV DNA levels < 5 x 10(4) copies/mL (range < 10(3)-2 x 10(3)), significantly lower than at baseline. At 36 months, 2 of 8 (25%) showed HBV DNA levels persistently lower than 5 x 10(4) copies/mL (1.7 x 10(3), 6 x 10(3)). The LightCycler quantitative real-time PCR is a practical, sensitive, reproducible single-tube assay with a wide dynamic range of detection. The assay is automatic except for DNA extraction and the running time is only 70 min. The LightCycler real-time PCR is useful for identifying different states of HBV infection and for evaluating the efficacy of viral therapy.

Second-generation Hybrid capture test and Amplicor monitor test generate highly correlated hepatitis B virus DNA levels

The performance of the Digene Hybrid Capture II HBV DNA Test HC II and the Roche Cobas Amplicor Monitor Test (Cobas-HBV) was evaluated on 252 serum samples. One hundred and seventy-three samples were HBV DNA positive and 75 HBV DNA negative by both assays. Four samples were HBV DNA positive by Cobas-HBV only. Linear regression analysis showed that the HBV DNA concentrations obtained from both assays were significantly related (n=173, r=0.976, P<0.0001). The results of the study show that Hybrid capture II and Cobas-HBV could be used equally in the management for patients with chronic HBV infection.

Comparative evaluation of semiautomated COBAS AMPLICOR hepatitis B virus (HBV) monitor test and manual microwell plate-based AMPLICOR HBV MONITOR test

Comparative evaluation of the semiautomated COBAS AMPLICOR hepatitis B virus (HBV) MONITOR Test (COBAS-HBV) and manual AMPLICOR HBV MONITOR Test (AMPLICOR-HBV) on 208 serum samples revealed no significant difference in the sensitivities of the two assays. Twenty samples tested HBV DNA negative and 183 samples tested HBV DNA positive by both assays. Three samples tested positive by COBAS-HBV only and two samples tested positive by AMPLICOR-HBV only. HBV DNA concentrations determined by the two assays were significantly related (n = 183, r = 0.97, P < 0.0001), which indicates that COBAS-HBV could replace AMPLICOR-HBV. The major inconvenience of COBAS-HBV is the required performance of appropriate predilutions of high-titer samples in order to extend the narrow dynamic range of the assay.

No significant correlation exists between core promoter mutations, viral replication, and liver damage in chronic hepatitis B infection

Hepatitis B virus (HBV) core promoter mutants have been proposed to contribute to severe liver damage by increasing viral loads, but this has not yet been clearly shown. To examine the effects of core promoter mutants on viral load and liver damage, we first developed a polymerase chain reaction (PCR)-based semiquantitative HBV DNA detection method with a high sensitivity (able to detect as low as 10(3) molecules/mL). Then we cloned 12 predominant core promoter mutants from 41 chronic hepatitis B patients. The in vitro promoter and replication activities of these mutants were similar to those of wild-type virus. However, viral load was highly variable, and this was dependent on individual patients rather than mutant type. In addition, there was no mutant type that showed any unique correlation with alanine transaminase (ALT) levels. Viral load was not significantly correlated with ALT level in both cross-sectional and longitudinal studies. Quantitation of HBV levels also revealed no clear correlation between hepatitis B e antigen (HBeAg) status and viral load. Taken together, these results indicated that the replication activity of core promoter mutants has little effect on viral load, and that viral load does not correlate with the severity of liver damage or with HBeAg status.

Combination therapy with lamivudine and famciclovir for chronic hepatitis B-infected Chinese patients: a viral dynamics study

In vitro studies have shown that lamivudine and penciclovir (the active metabolite of famciclovir) act synergistically to inhibit hepatitis B virus (HBV) replication. We compared the effectiveness of HBV viral suppression by lamivudine monotherapy versus lamivudine plus famciclovir combination therapy in Chinese patients with chronic HBV infection. Twenty-one Chinese hepatitis B e antigen (HBeAg)-positive patients, with detectable HBV DNA (Digene Hybrid Capture II), were randomized to receive either lamivudine 150 mg/d orally (group 1, 9 patients) or lamivudine 150 mg/d plus famciclovir 500 mg 3 times a day orally (group 2, 12 patients) for 12 weeks, with a follow-up period of at least 16 weeks. Serial serum HBV-DNA levels were determined and a mathematical model with provision for incomplete inhibition of virus production during therapy was applied to analyze the dynamics of viral clearance. The mean antiviral efficacy was significantly greater in group 2 than in group 1 (0.988 +/- 0.012 vs. 0.94 +/- 0.03, P =.0012). HBV DNA returned to pretreatment level within 16 weeks after the end of initial treatment in 4 patients (66.7%) in group 1 and none in group 2 (P =.08), who remained HBeAg positive and received no further treatment after week 12. Hence, in Chinese chronic HBeAg-positive patients, combination therapy using lamivudine and famciclovir was superior to lamivudine monotherapy in inhibiting HBV replication. Further studies of longer duration are needed to define whether combination therapy will increase the HBeAg seroconversion rate and decrease the rate of emergence of lamivudine-resistant variants.