Comparison of three different sensitive assays for hepatitis B virus DNA in monitoring of responses to antiviral therapy

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.

Chronic hepatitis B in Asia-new insights from the past decade

Chronic hepatitis B virus (HBV) infection is a major health problem in the Asia-Pacific region. In the past decade, much progress has been made in the understanding and management of this disease. The introduction of universal vaccination has significantly reduced the incidence of perinatal infection in most Asia-Pacific countries. As the majority of the adult population have not been immunized at birth, we are still facing a large population of young HBV-infected patients in the coming two decades. The study of long-term longitudinal databases has provided deeper insight into the clinical significance of HBV DNA suppression, hepatitis B e antigen (HBeAg) seroconversion and hepatitis B surface antigen (HBsAg) seroclearance in chronic hepatitis B. With a better understanding on the natural history of HBV infection, one can now stratify the risk of chronic hepatitis B patients for adverse clinical outcomes and use this to individualize management. The introduction of non-invasive assessment of liver fibrosis can potentially reduce the necessity of liver biopsy. There have also been great advances in the development of antiviral therapy in the past decade. However, the high cost of HBV antiviral drugs poses major challenges to health authorities in many Asia-Pacific countries. Properly performed cost-effective analysis and understanding on the best timing of stopping antiviral drugs will be important to facilitate the most appropriate allocation of resources.

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.

Chronic HBV-related liver disease

Thirty years after its discovery, the hepatitis B virus (HBV) still remains a major global public health problem. Worldwide, two billion subjects have been infected, 300 million have a chronic infection and more than 600,000 die annually of HBV-related liver disease or hepatocellular carcinoma; new infections occur because of the presence of a large reservoir of chronic carriers of the virus. The knowledge of the HBV organization and replication cycle and the availability of sensitive HBV-DNA assays have led to remarkable progress in our understanding of the natural history of chronic hepatitis B infections. Crucial to the prevention of new infections, to the management and the monitoring of HBV carriers and to the choice of best treatment strategy, is the understanding of the natural dynamism of HBV infection and of the virus-host interactions that induce liver damage.

Molecular diagnostics for the detection and characterization of microbial pathogens

New and advanced methods of molecular diagnostics are changing the way we practice clinical microbiology, which affects the practice of medicine. Signal amplification and real-time nucleic acid amplification technologies offer a sensitive and specific result with a more rapid turnaround time than has ever before been possible. Numerous methods of postamplification analysis afford the simultaneous detection and differentiation of numerous microbial pathogens, their mechanisms of resistance, and the construction of disease-specific assays. The technical feasibility of these assays has already been demonstrated. How these new, often more expensive tests will be incorporated into routine practice and the impact they will have on patient care remain to be determined. One of the most attractive uses for such techniques is to achieve a more rapid characterization of the infectious agent so that a narrower-spectrum antimicrobial agent may be used, which should have an impact on resistance patterns.

Two-year Lamivudine treatment for Hepatitis B e Antigen-Negative Chronic Hepatitis B: A Double-Blind, Placebo-Controlled Trial

Objective

We conducted a multicentre, double-blind, placebo-controlled, randomized study to investigate the efficacy of 2-year lamivudine treatment in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B.

Methods

One-hundred-and-thirty-nine treatment-naive patients with HBeAg-negative chronic hepatitis B were randomized to receive either lamivudine (100 mg daily) or placebo in a 2:1 ratio for 24 months and were followed for an additional 6 months. The primary endpoint was complete response, defined as hepatitis B virus (HBV) DNA <10,000 copies/ml and normalization of alanine aminotransferase (ALT) levels at month 24.

Results

On intent-to-treat analysis at month 24, significantly more patients in the lamivudine group than in the placebo group had complete response (56% and 11%, respectively; P<0.001) or negative HBV DNA (26% and 6%, respectively; P=0.006). After adjustment of baseline HBV DNA and ALT, the odds ratio for complete response of the lamivudine group versus the placebo group was 10.8 (95% confidence interval: 3.8–30.2; P<0.001). The median log HBV DNA reduction was 3.21 copies/ml for the lamivudine group compared with 0.47 copies/ml for the placebo group ( P<0.001). Genotypic resistance was detected in 23% and 31% of patients in the lamivudine group at months 12 and 24, respectively. Negative HBV DNA at month 6 was associated with high complete response (84%) and low drug resistance (1%) at month 24. At month 30, there was no difference between lamivudine and placebo groups in the rates of complete response (26% vs 19%, respectively; P=0.38) or negative HBV DNA (10% vs 2%, respectively; P=0.09).

Conclusions

Two-year lamivudine treatment is effective in HBeAg-negative chronic hepatitis B. However, the response is not sustained after treatment cessation.

Intrahepatic hepatitis B virus covalently closed circular DNA can be a predictor of sustained response to therapy

BACKGROUND & AIMS

This study aimed to determine whether intrahepatic hepatitis B virus (HBV) covalently closed circular (ccc) DNA and total HBV DNA levels at the end of therapy would predict sustained response to therapy.

METHODS

Hepatitis B e antigen (HBeAg)-positive chronic hepatitis B patients receiving either lamivudine monotherapy or combination of peginterferon and lamivudine had liver biopsy at the end of 1 year therapy and were followed for 52 more weeks after cessation of therapy. Serum HBV DNA, intrahepatic HBV ccc DNA, and total HBV DNA levels were determined.

RESULTS

Forty-seven patients, including 34 males and 13 females, were studied. Twenty-seven patients received combination therapy, and 20 patients received lamivudine monotherapy. Twenty-nine patients had end-of-treatment virologic response, and 15 patients had sustained response 52 weeks after therapy. At the end of treatment, log serum HBV DNA levels correlated well with log intrahepatic HBV cccDNA and log intrahepatic total HBV DNA levels. Log intrahepatic cccDNA and log intrahepatic total DNA levels were significantly lower among patients with sustained virologic response. The adjusted odds ratio for log cccDNA was 5.3 (95% CI: 1.5-18.2, P = .009) and, for log intrahepatic HBV DNA, was 4.4 (95% CI: 1.3-14.7, P = .015) to predict sustained virologic response. Using log cccDNA at -0.80 copies/genome equivalent as cutoff, the sensitivity, specificity, and positive and negative predictive values and accuracy of predicting sustained virologic response were 73%, 78%, 56%, 86%, and 77% respectively.

CONCLUSIONS

Intrahepatic HBV cccDNA and intrahepatic total HBV DNA levels at the end of therapy are superior to serum HBV DNA as surrogates of sustained virologic response.

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.

Clinical course after stopping lamivudine in chronic hepatitis B patients with lamivudine-resistant mutants

BACKGROUND

The efficacy of lamivudine therapy in chronic hepatitis B is well established. However, drug-resistant YMDD mutants emerge with extended therapy. This may result in the resurgence of viral replication, the return of hepatitis and histological deterioration.

AIM

To study the safety of stopping lamivudine when the drug is no longer effective.

METHODS

In the 5-year Asian Lamivudine Study, 34 patients from a single centre were included in this study. They had harboured YMDD mutants for at least 2 years. Lamivudine was discontinued and they were followed up at regular intervals. Clinical symptoms, liver biochemistry and viral serology were monitored.

RESULTS

In a median follow-up of 20 months after stopping lamivudine (range, 7-39 months), 20 of the 34 patients (58.8%) had elevated alanine aminotransferase (ALT), 13 patients (38.2%) had elevated ALT one to five times the upper limit of normal and seven patients (20.6%) had an ALT flare (ALT more than five times the upper limit of normal with detectable hepatitis B virus DNA). There was no liver decompensation. ALT flare could be predicted by ALT over twice the upper limit of normal at the time of stopping lamivudine (P = 0.037).

CONCLUSIONS

It is relatively safe to stop lamivudine after YMDD mutants have emerged. ALT levels greater than or equal to twice the upper limit of normal at the time of stopping lamivudine have a higher risk for ALT flare.

Hepatitis B virus genotype has no impact on hepatitis B e antigen seroconversion after lamivudine treatment

AIM: To investigate the association of hepatitis B virus (HBV) genotype and HBeAg seroconversion after nucleotide analogue treatment.

METHODS: Chronic hepatitis B patients receiving lamivudine followed up for at least 6 months post-treatment were studied. Consecutive treatment-naïve patients who were prospectively followed up in the clinic for at least 18 months were studied as controls. HBeAg seroconversion was defined as loss of HBeAg, appearance of anti-HBe and normalization of alanine aminotransferase for at least 6 months.

RESULTS: Thirty-five patients on lamivudine and 96 control patients followed up for 39 (18-49) months were studied. Lamivudine was given for 12 (10-18) months, and patients were followed up for 15 (6-34) months after drug cessation. Genotype B and C HBV were found in 43 and 88 patients and HBeAg seroconversion occurred in 12 (28%) and 16 (18%) patients, respectively (P = 0.30). There was no difference in HBeAg seroconversion between patients infected by genotype B and C HBV in the control (35% vs 21%, P = 0.25) and lamivudine-treated (14% vs 10%, P = 1.00) groups.

CONCLUSION: HBeAg seroconversion after treatment by lamivudine was not influenced by the HBV genotype.

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.

Double-blinded placebo-controlled study of Phyllanthus urinaris for the treatment of chronic hepatitis B

BACKGROUND

Previous studies suggested that Phyllanthus species have an anti-viral effect on hepatitis B, but methodologies have been inadequate.

AIMS

This study aimed to investigate the anti-viral effect of Phyllanthus urinaris.

METHODS

Chronic hepatitis B patients with positive hepatitis B e-antigen (HBeAg), hepatitis B virus (HBV) DNA > 500 000 copies/mL and elevated alanine transaminase (ALT) were recruited. Patients were randomized into groups of 12 receiving P. urinaris 1, 2 and 3 g three times daily for 6 months or placebo (six cases). The primary endpoint was HBV DNA reduction, and secondary endpoints were HBeAg seroconversion and ALT normalization.

RESULTS

On an intention-to-treat analysis there was no difference in log10[HBV DNA] reduction of the Phyllanthus 1-g (0.18 +/- 1.42), 2-g (0.33 +/- 1.08) and 3-g (0.85 +/- 1.30) groups vs. placebo (0.28 +/- 0.85) (P = 0.90, 0.92 and 0.38, respectively) at the end of treatment. The percentage of patients among the placebo, Phyllanthus 1-g, 2-g and 3-g groups undergoing HBeAg seroconversion (0%, 9.1%, 8.3% and 16.7%, respectively) and ALT normalization (0%, 0%, 8.3% and 33.3%) were not significantly different at the end of treatment. No delayed virological or biochemical response was documented at 24 weeks after the cessation of treatment. No serious adverse event was reported.

CONCLUSION

P. urinaris treatment for 6 months has no demonstrable anti-viral effect in chronic hepatitis B.

Hepatitis B virus genotype C takes a more aggressive disease course than hepatitis B virus genotype B in hepatitis B e antigen-positive patients

One hundred forty-six hepatitis B e antigen (HBeAg)-positive chronic hepatitis B patients were followed up for 32 +/- 13 months. All six patients with hepatocellular carcinoma had hepatitis B virus (HBV) genotype C. Disease activity was greater in patients infected by HBV genotype C than in those infected by HBV genotype B in the HBeAg-positive phase but not after HBeAg seroconversion.

The role of lamivudine and predictors of mortality in severe flare-up of chronic hepatitis B with jaundice

Patients with chronic hepatitis B (CHB) may develop severe disease exacerbations (flare) with jaundice, and some may progress to fulminant hepatic failure. Whether early administration of lamivudine can prevent liver failure and mortality is uncertain. We investigated the role of lamivudine treatment in severe hepatitis B virus (HBV) exacerbations. Consecutive patients presented with severe flare-up of HBV (new onset of jaundice plus alanine aminotransferase greater than five times upper limit of normal) treated with lamivudine and historical controls who did not receive lamivudine were studied. All patients had no hepatic encephalopathy on admission. Univariate analysis and multivariate logistic regression were performed on various clinical and laboratory factors for the prediction of mortality. Twenty-eight patients treated with lamivudine and 18 controls were identified. Overall, nine patients died and two other received liver transplants for fulminant hepatic failure. Six of 28 (21.4%) lamivudine-treated patients vs five of 18 (27.8%) controls died or received a liver transplant (P = 0.62). On multivariate analysis, platelet < or = 143 x 10E9/L (odds ratio 22.4, 95% CI 1.8-281.6) and bilirubin > 172 micromol/L (odds ratio 18.4, 95% CI 1.5-228.5) were independent predictors of liver-related mortality. The mortality of patients who had thrombocytopenia and high bilirubin, thrombocytopenia, high bilirubin, and no risk factor were 69.2%, 11.1%, 12.5% and 0% respectively. Hence lamivudine confers no survival benefit to conventional treatment in severe exacerbations of CHB. Patients with thrombocytopenia and high bilirubin should be considered for liver transplantation.

Genotype B hepatitis B virus is associated with severe icteric flare-up of chronic hepatitis B virus infection in Hong Kong

OBJECTIVE

We aimed to investigate the association of viral genotype and the development of icteric flare-up (IF) in chronic hepatitis B virus (HBV) infection.

METHODS

Twenty-one consecutive patients suffering from IF of chronic HBV infection, defined as elevation of ALT over five times the upper limit of normal, together with either bilirubin > 50 IU/L or elevated bilirubin plus PT > 3 s prolonged, were studied. Patients from three stages of HBV-related chronic liver disease were studied as controls: 1) asymptomatic carriers (31 patients), defined as persistent normal ALT for at least 2 yr; 2) active early cirrhosis (49 patients), defined as Child's A liver cirrhosis plus HBV DNA > 106 Eq/ml; and 3) decompensated cirrhosis (31 patients), defined as Child's B or C liver cirrhosis with complications. Restriction fragment length polymorphism was used for genotyping.

RESULTS

Only genotype B and C HBV were identified in our studied cohort. Ninety-one percent of patients suffering from IF were infected by genotype B HBV (p < 0.001 vs asymptomatic carriers, early cirrhosis patients, and decompensated cirrhosis patients). On the contrary, genotype C HBV was the predominant strain at different stages of chronic liver disease; no statistical difference was found on the relative prevalence of genotype B/C HBV among asymptomatic carriers, early cirrhosis patients, and decompensated cirrhosis patients.

CONCLUSIONS

Genotype B HBV is associated with IF among chronic HBV-infected patients in Hong Kong, whereas genotype C HBV is more prevalent at all stages of chronic liver disease. Our findings suggested that the two different HBV genotypes might have different pathogenic mechanisms of liver damage.

Occult HBV infection in cryptogenic liver cirrhosis in an area with high prevalence of HBV infection

OBJECTIVES

Hepatitis B surface antigen (HBsAg) is often used as the serological marker to screen for hepatitis B virus (HBV) infection in the investigation of liver cirrhosis. In Hong Kong, where HBV infection is endemic, some patients may have persistent viral infection after the loss of HBsAg. We aimed to investigate 1) the prevalence of occult HBV infection in cryptogenic liver cirrhosis in Hong Kong and 2) the role of HBV "a" determinant mutations among these patients.

METHODS

Twenty-eight patients with cryptogenic liver cirrhosis (group I), 49 subjects with no liver disease (group II), and 26 patients with HBV-related cirrhosis (group III) were studied. HBV DNA was determined by the cross-linking assay (sensitivity = 0.5 mEq/ml) and polymerase chain reaction (PCR). Occult HBV infection was defined as HBV DNA detectable by PCR among patients with negative HBsAg.

RESULTS

Eighty-nine percent and 92% of patients in groups I and II, respectively, had positive anti-HBs and/or anti-hepatitis B core. Nine (32%), no (0%), and 14 (54%) patients in groups I, II, and III, respectively, had detectable HBV DNA by PCR (group I vs group II, p < 0.001; group I vs group III, p = 0.36). Four patients in group I had HBV DNA detectable by the cross-linking assay (median = 5.98 mEq/ml, range = 3.1-8.01). "a" determinant mutations were detected in two patients in group I (K122N and G145R, C125A) and one patient in group II (1126N).

CONCLUSIONS

Occult HBV infection is common among patients with cryptogenic liver cirrhosis, and it cannot be explained by mutations in the HBV "a" determinant.

Relationship of clinical and virological factors with hepatitis activity in hepatitis B e antigen-negative chronic hepatitis B virus-infected patients

To investigate the factors associated with active disease among hepatitis B surface antigen (HBsAg) positive/hepatitis B e antigen (HBeAg)-negative chronic hepatitis B virus (HBV) infection we studied chronic HBV infected patients who had undetectable HBeAg at the first visit. HBV DNA was determined by the cross-linking assay (NAXCOR) and polymerase chain reaction (PCR). Mutations in the core promoter and precore regions and viral genotypes were studied. Clinical outcome of these patients were followed and categorized as: (i) relapse (ALT > 200 IU/L or three times the previous levels); (ii) active hepatitis (elevated ALT < 200 IU/L with concomitant detectable HBV DNA); or (iii) remission. A total of eighty-five patients were followed up for 5.5 +/- 1.0 years. At first visit, 31 (36.5%) patients had elevated ALT levels, 12 (14.1%) had measurable HBV DNA by the cross-linking assay and 26 (30.6%) by PCR. Sixteen (18.8%) patients had hepatitis relapse, 13 (15.3%) had active hepatitis, and 56 (65.9%) remained in remission. Core promoter and precore stop codon mutants were found in 27 and 12 patients, respectively. Eleven and 20 had genotype B and C HBV, respectively. Initial elevated ALT and detectable HBV DNA were associated with active liver disease. Patient demographics, viral mutants or genotypes failed to predict disease activity. Hence, serum ALT and HBV DNA levels offer the best prediction of natural course of HBeAg-negative chronic HBV infection.

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.

Viral genotype and hepatitis B virus DNA levels are correlated with histological liver damage in HBeAg-negative chronic hepatitis B virus infection

OBJECTIVES

We aimed to study the relationship between the hepatitis B virus (HBV) genotypes, core promoter/precore stop codon mutations, and histological liver damage among hepatitis B e antigen (HBeAg)-negative patients.

METHODS

Liver biopsy specimens of 55 HBeAg-negative chronic HBV-infected patients were studied. A histological activity index was scored for degree of necroinflammation (HAI-NI) and fibrosis (HAI-F) as described by Knodell et al. HBV DNA was determined by a cross-linking assay and polymerase chain reaction (PCR) at the core promoter/precore region and the S region. PCR-positive samples were directly sequenced for core promoter and precore mutations and examined by restriction fragment length polymorphism for genotyping.

RESULTS

Forty-one males and 14 females at a median age of 43 were studied. HBV DNA was detectable in 32 (58%) and 37 (67%) patients by the cross-linking assay and PCR, respectively, at the time of liver biopsy. The median (range) HAI-NI and HAI-F scores were 5 (1-10) and 2 (0-4), respectively. HBV DNA detectable by either the cross-linking assay or PCR was associated with a higher HAI-NI score. Eleven and 31 patients had genotypes B and C HBV, respectively. Genotype C HBV was associated with higher HAI-NI than genotype B HBV. Core promoter mutations and precore stop codon mutation were detected in 74% and 40% patients, respectively, but they were not associated with higher HAI-NI or HAI-F scores.

CONCLUSIONS

Detectable HBV DNA and genotype C HBV, but not core promoter or precore stop codon mutations, are associated with more severe liver damage in HBeAg-negative patients.

Laboratory diagnosis of viral hepatitis

Both serologic and molecular assays are useful in the diagnosis of viral hepatitis. They may detect early infections before other signs of disease appear, differentiate acute from chronic infections, and detect persistence of viremia or verify development of immunity. Molecular assays may also be used to monitor responses to antiviral therapy, and in the future, be a primary method to screen blood and organ donors (NAT). EIA serologies are used to diagnose acute HAV infections or establish immune status. Similar immunoassays are used to detect HBV infections, verify persistence of antigenemia and degree of infectivity, and indicate immunity (including the response to vaccination). HBV molecular assays can shorten the diagnostic window period, verify persistence of viremia, including monitoring response to antiviral therapy, and be useful in NAT screening of donors. Molecular assays play a major role in HCV diagnosis where serologic tests can document past or present infection but cannot differentiate one from the other. A variety of molecular tests can be used as sensitive (and early) detectors of viremia (and serve as confirmatory tests for positive serologies and as donor NAT methods), document its persistence as an indicator of chronic infection, and monitor responses to antiviral therapy. Both qualitative and quantitative molecular assays are available, and their efficient use requires familiarity with the sensitivity and dynamic ranges of each method.

Clinical application of pharmacogenetics

Pharmacogenetics encompasses the involvement of genes in an individual's response to drugs. As such, the field covers a vast area including basic drug discovery research, the genetic basis of pharmacokinetics and pharmacodynamics, new drug development, patient genetic testing and clinical patient management. Ultimately, the goal of pharmacogenetics is to predict a patient's genetic response to a specific drug as a means of delivering the best possible medical treatment. By predicting the drug response of an individual, it will be possible to increase the success of therapies and reduce the incidence of adverse side effects.