Genetic variation in hepatitis B virus

Precore/core mutations of hepatitis B virus genotype D arising in different states of infection

Aim of the study

Precore/core variations and liver disease progression have been suggested. In this study, we aimed to determine the frequency of precore/core mutations in hepatitis B virus (HBV)-infected patients at various clinical stages.

Material and methods

In total, 73 HBV-infected patients including 26 inactive carriers (IC), 20 chronic active (CA), and 27 patients with liver cirrhosis/hepatocellular carcinoma (C/HCC) were randomly selected. The HBV DNA was extracted from the sera and subjected to nested PCR for amplification of precore/core region. The PCR product was then sequenced by the Sanger method.

Results

The stop codon of W28*(G1896A) was determined as the most prevalent mutation (55%) of the precore region. The comparison of groups also demonstrated that core substitutions at residues of S21, E40 and I105 (< 0.05) correlated with the development of the inactive carrier state. Furthermore, the total substitutions in Th epitopes (117-131) were significantly higher in the C/HCC group than the IC and CA groups (p = 0.001).

Conclusions

Our results indicated a high frequency of W28* mutation in HBV studied patients. Moreover, variations including S21, E40 and I105 and R151 that were mapped onto cellular epitopes might be related to inactive state development.

Hepatitis B virus-induced hepatocarcinogenesis: A virological and oncological perspective

Hepatitis B virus (HBV) is a partially double-stranded DNA virus associated with hepatocellular carcinoma (HCC). The viral integration into the hepatocyte genome, the viral protein-induced oncogenesis, the increased hepatocyte turnover and the chronic inflammatory response towards HBV are all hypothesized mechanisms for the development of HCC. The fact that HBV infection and HCC prevalence show different correlations in various regions of the world indicates that there may be virus-independent phenomena for cancer development in these regions. From this point of view, it is important to review our knowledge and to examine the relationship between HBV and HCC in the light of current data. In this article, we investigate the relationship between HBV and HCC by presenting epidemiological and microbiological data, accompanied by the principles of viral oncogenesis.

In vitro transcribed mRNA for expression of designer nucleases: Advantages as a novel therapeutic for the management of chronic HBV infection

Chronic infection with the hepatitis B virus (HBV) remains a significant worldwide medical problem. While diseases caused by HIV infection, tuberculosis and malaria are on the decline, new cases of chronic hepatitis B are on the rise. Because often fatal complications of cirrhosis and hepatocellular carcinoma are associated with chronic hepatitis B, the need for a cure is as urgent as ever. Currently licensed therapeutics fail to eradicate the virus and this is attributable to persistence of the viral replication intermediate comprising covalently closed circular DNA (cccDNA). Elimination or inactivation of the viral cccDNA is thus a goal of research aimed at hepatitis B cure. The ability to engineer nucleases that are capable of specific cleavage of a DNA sequence now provides the means to disable cccDNA permanently. The scientific literature is replete with many examples of using designer zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and RNA-guided endonucleases (RGENs) to inactivate HBV. However, important concerns about safety, dose control and efficient delivery need to be addressed before the technology is employed in a clinical setting. Use of in vitro transcribed mRNA to express therapeutic gene editors goes some way to overcoming these concerns. The labile nature of RNA limits off-target effects and enables dose control. Compatibility with hepatotropic non-viral vectors is convenient for the large scale preparation that will be required for advancing gene editing as a mode of curing chronic hepatitis B.

Entecavir-resistant hepatitis B virus decreases surface antigenicity: A full genome and functional characterization

BACKGROUND AND AIM

Since polymerase and surface genes overlap in hepatitis B virus (HBV), an antiviral-induced mutation in the polymerase gene may alter the surface antigenicity in patients with chronic hepatitis B (CHB), but this possibility has not been clearly confirmed. This study aimed to determine the drug susceptibility and surface antigenicity of the patient-derived mutants.

PATIENTS AND METHODS

Full-length HBV genomes isolated from four entecavir-resistant CHB patients were cloned and sequenced. Around 10 clones of full-length HBV obtained from each patient were analysed and registered in the NCBI GenBank. Representative clones were further characterized by in vitro drug susceptibility and surface antigenicity assays.

RESULTS

The rtL180M + rtM204V mutations were common among all the clones analysed. Additionally, the ETV resistance mutations rtT184A/L, rtS202G and rtM250V were found among three patients. Most of the ETV-resistant mutants had amino acid alterations within the known epitopes recognized by T- and B-cells in the HBV surface and core antigens. The in vitro drug susceptibility assay showed that all tested clones were resistant to ETV treatment. However, they were all susceptible to ADV and TDF. More importantly, the rtI169T mutation in the RT domain, led to the sF161L mutation in the overlapping S gene, which decreased in surface antigenicity.

CONCLUSIONS

The ETV resistance mutations can affect the antigenicity of the HBsAg proteins due to changes in the overlapping sequence of this surface antigen. Thus, the apparent decline or disappearance of HBsAg needs to be interpreted cautiously in patients with previous or current antiviral resistance mutations.

Hepatitis B Awareness among Medical Students and Their Vaccination Status at Syrian Private University

Background. Hepatitis B virus (HBV) is a potentially life-threating infection and a well-recognized occupational hazard for health-care workers including medical students. Methods. A cross-sectional study was conducted at Syrian Private University (SPU), Faculty of Medicine, to assess the knowledge and awareness about hepatitis B, the status of hepatitis B vaccination, and the reasons for not getting vaccinated among the first- and the fifth-year medical students. Results. The present study demonstrates surprising results and raises issues about the high number of medical students that are not vaccinated or not sure about their vaccination status, which puts them at a higher risk of being infected in the future. Another important issue is the medical students' overall knowledge about this life-threating infection. The students have not been totally educated about the gravity of the situation which requires the need of further HBV education. It is highly recommended that SPU provides the HBV vaccine to all nonvaccinated students attending the faculty of medicine at no cost to encourage them to take the HBV vaccine and to reform some of its educational curriculum to effectively limit the hazardous effects of this disease and elaborate on the serious health consequences of HBV.

Prevalence of hepatitis B and hepatitis C viral infections in Indian patients with chronic renal failure

The present study reports prevalence of posttransplant hepatitis B virus (HBV) and hepatitis C virus (HCV) infection in 256 patients with chronic renal failure (CRF) and with a history of either renal transplant or hemodialysis. Out of 256 patients 138 had renal transplant and 118 were on maintenance hemodialysis. Among the patients screened, 7% had HBV infection alone, 46% were infected with HCV alone, while 37.10% were found to have co-infection of both the viruses. Our findings implicate these viruses as the major cause of posttransplant hepatitis in Indian patients with CRF and indicate implementation of stringent screening procedures for these two viral infections.

A randomized, controlled, clinical study of thymosin alpha-1 versus interferon-alpha in [corrected] patients with chronic hepatitis B lacking HBeAg in China [corrected]

BACKGROUND

This study was designed to compare the efficacy and safety of thymosin-alphal (T-alpha1) with that of interferon-alpha (IFN-alpha) in patients with chronic hepatitis B who were positive for hepatitis B virus (HBV) DNA and hepatitis B envelope antibody (anti-HBe).

METHODS

Fifty-six patients were randomly divided into groups A and B. Both groups were comparable (p > 0.05) at baseline regarding age, sex, and alanine aminotransferase (ALT) levels. Group A patients received T-alpha1 1.6 mg subcutaneously twice weekly, while group B patients received IFN-alpha 5 million IU daily for 15 days, then thrice weekly for 6 months. Results from the 2 groups were compared with data from a group of 30 patients never treated with IFN-alpha and who were followed-up for 12 months (historical control [HC] group); the 3 groups were comparable (p > 0.05).

RESULTS

After treatment, a complete response (ALT normalization and HBV DNA loss) occurred in 8 of 26 patients in group A (30.8%) and 14 of 30 in group B (46.7%; chi2 = 1.476, p = 0.224). After a follow-up period of 6 months, a complete response was observed in 11 of 26 patients in group A (42.3%) and 7 of 30 in group B (23.3%; chi2 = 2.299, p = 0.129). The rate of complete response was significantly greater in the IFN-alpha than HC group at the end of therapy (46.7% vs 3.3%; chi2 = 15.022, p = 0.0001), and in the T-alphal than HC group at the end of follow-up (42.3% vs 3.3%; chi2 = 12.566, p = 0.0001). Ten of the 12 T-alphal responders (i.e. partial responders; 83.3%) experienced sustained, non-detectable HBV DNA after 6 months' treatment; 6 of the 14 T-alphal non-responders (42.9%) showed a delayed response of non-detectable HBV DNA during the follow-up period. Corresponding values for group B patients were 50% (9/18) and 0% (0/12). The rate of delayed response was significantly higher in group A than the other 2 groups (chi2 = 6.686, p = 0.010; chi2 = 4.964, p = 0.038), whereas the rate of flare was higher in group B than in the other 2 groups (chi2 = 3.445, p = 0.063; chi2 = 7.668, p = 0.006), during the follow-up period. Unlike IFN-alpha, T-alphal was well tolerated, i.e. no adverse effects were noted in group A.

CONCLUSION

These results suggest that a 6-month course of T-alpha1 therapy is effective and safe in patients with anti-HBe-positive chronic hepatitis B; T-alpha1 can reduce HBV replication in such patients. Compared with IFN-alpha, T-alpha1 is better tolerated and seems to induce a gradual and more sustained normalization of ALT and loss of HBV DNA. Combination therapy with T-alpha1 and IFN-alpha or nucleoside analogs for hepatitis B warrants further study.

Origin of serum hepatitis B virus in acute exacerbation: comparison with HBV in the liver and from other exacerbation

Acute exacerbation (AE) of chronic hepatitis B is usually preceded by reemergence or increase of hepatitis B virus (HBV) in the serum. To investigate the origin of the reemergence or increase, we compared the identity of the serum viral genome to that in the liver and in previous AE by full-length sequencing. The full-length viral genome and extent of quasispecies were obtained from serum and liver biopsy specimens at the same time from 9 subjects with hepatitis B exacerbation (group I). Composition of viral quasispecies was compared by the genetic diversity and the average number of nucleotide substitutions within and between different viral sources. Another 2 patients with repeated AEs (group II) were also enrolled, and their serial serum alanine aminotransferase, HBV DNA levels and full-length sequences were determined. In all group I patients, serum viral genome was identical to that in the liver. The genetic diversity and the average number of nucleotide difference were also comparable between serum and liver tissue. In 2 group II patients, the viral variant that emerged after previous AE was not identical to that caused by the subsequent AE. Dominant viral strains for serial AEs in a single patient did not show a sequential evolution, but presented as a horizontal selection of a minor population from the original viral pool. In conclusion, the findings suggest that viral strain in serum reflects the intrahepatic strain of the AE. Random reactivation of the original HBV pool, rather than a sequential evolution of one strain, also contributes to the onset of repeated AE. Supplementary material for this article can be found on the HEPATOLOGY website (http://interscience.wiley.com/jpages/0270-9139/suppmat/index.html).

Hepatitis B virus (HBV) vaccine-induced escape mutants of HBV S gene among children from Qidong area, China

Hepatitis B virus (HBV) infection is the main factor, which induces hepatocellular carcinoma (HCC) in Qidong high-risk area, China. To prevent HBV infection is the most important strategy to inhibit the HCC carcinogenesis. A large project was performed in Qidong area to protect newborn babies from the HBV infection that 80,000 children born between 1984 and 1990 were vaccinated. After three times of follow-up studies, 15 screened children were found to have symptoms of illness showing persistent elevation of serum glutamic-pyruvic transaminase (ALT). From these previously collected data, we found that the ALT levels of five vaccinees with negative hepatitis B surface antigen (HBsAg) were significantly higher than those of 10 vaccinees with positive HBsAg. Furthermore, with the passage of time, the difference of ALT levels between the two groups (HBsAg negative and positive groups) diminishes. After cloning and sequencing of the HBsAg "a" epitope coding sequences, we found that mutations in "a" epitope were correlated with the absence of detectable anti-HBsAg, while no mutations were seen in the anti-HBsAg positive infections. We also found that majority of point mutations were occurred in the coding sequences of the first loop structure in "a" epitope. The structure of double loop conformation in "a" epitope was conservative, and important for HBV antigenicity. These changes in a double loop conformation would escape neutralization by vaccine-induced antibody.

A novel stop codon mutation in HBsAg gene identified in a hepatitis B virus strain associated with cryptogenic cirrhosis

AIM: HBsAg is the most important serological marker for acute or chronic hepatitis B. Nevertheless, there were reports of HBsAg-negative infection caused by hepatitis B virus in recent years. We had a patient with crytogenic cirrhosis who was negative for HBsAg, positive for anti-HBs and HBeAg. This paper was to explore the pathogenic and molecular basis of the unusual serological pattern.

METHODS: HBV serologic markers were qualitatively and quantitatively determined. HBV DNA in serum was qualitatively tested using routine Polymerase chain reaction(PCR), and the viral level was determined with real-time fluorescence quantitative PCR. HBsAg gene was amplified and cloned. Four clones were sequenced. The new genomic sequences were compared with GenBank on the DNA level as well as the protein level.

RESULTS: The qualitative results of serological markers were HBsAg(-), anti-HBs(+), HBeAg(+), anti-HBe(-) and anti-HBc(+). The quantitative results of serological marker were HBsAg (S/N): 0.77 (cut off of S/N: ≥ 2.00), HBeAg (S/N): 56.43 (cut off S/N: ≥ 2.10), anti-HBc (S/C_O): 2.03 (cut off of S/C_O: ≤ 1.00). The viral level was as high as 1.54 × 10⁹ copies/ml. Sequencing of the HBsAg gene clones revealed a unique point mutation at nucleotide 336 (C to A), which resulted in a novel stop codon at aa 61. The novel HBsAg gene stop mutation had not been described.

CONCLUSION: The lack of detection of HBsAg in the presence of high viral levels of replication may be caused by the existence of viral genomes harboring point mutations which resulted in stop codon upstream of the “a” determinant in HBsAg gene.

A novel hepatitis B virus mutant with A-to-G at nt551 in the surface antigen gene

AIM: Hepatitis B surface antigen (HBsAg) mutant of hepatitis B virus (HBV) is one of the important factors that result in immune escape and cause failure of immunization. In this study we reported and characterized a novel HBV mutant with A-to-G at nt551 and intended to provide theoretical data for prevention of HBV infection in China.

METHODS: A methodology comprising polymerase chain reaction (PCR) amplifying, M13 bacteriophage cloning and nucleotide sequencing was used to analyze the sera of the pediatric patient who was hepatitis B (HB) immune failure. Expression plasmids containing the mutant S gene and a wild-type (adr) S gene were constructed respectively and the recombinant HBsAg were expressed in COS-7 cells under the regulation of SV40 early promoter. The recombinant proteins were investigated for their immunological reactivity with different monoclonal antibodies (mAb) against 'a' determinant and vaccine-raised human neutralizing antibodies.

RESULTS: It was found that there was a new point mutation at nt551 of the HBV (adr) genome from A to G, leading to a substitution of methionine (Met) to valine (Val) at position 133 in the 'a' determinant of HBsAg. Compared to the wild-type HBsAg, the binding activity of the muant HBsAg to mAbs (A6, A11 and S17) and to vaccine-raised human anti-hepatitis B surface antibody (anti-HBs) decreased significantly.

CONCLUSION: According to the facts that the patient has been immunized with HB vaccine and that the serum is anti-HBs positive and HBsAg negative, and based on the nucleotide sequence analysis of the mutant HBV S gene and its alteration of antigenicity, the HBV is considered to be a new vaccine-induced immune escape mutant different from the known ones.

Selection of hepatitis B virus polymerase mutants with enhanced replication by lamivudine treatment after liver transplantation

BACKGROUND & AIMS

Lamivudine has become a main therapeutic option for treating hepatitis B virus (HBV) infection. Although drug resistance develops, the clinical course after selection of antiviral-resistant HBV mutants seems to be benign. However, we observed a severe clinical course of hepatitis B infection in several liver transplant recipients after the emergence of lamivudine resistance. This was associated with high viral load in the blood.

METHODS

In this report, we characterize the molecular mechanisms underlying drug-dependent enhanced replication of particular lamivudine-resistant HBV mutants selected in these patients, which were associated with sudden onset of liver failure.

RESULTS

The clinical course was characterized by a sudden rise in serum bilirubin, prothrombin time, and transaminase. HBV sequence analysis of these patients revealed both mutations in the "a-determinant" of the envelope and the YMDD (tyrosine, methionine, aspartate, aspartate) motif (domain C) of the polymerase protein. Transfection experiments with replication competent vectors indicated that the "a-determinant" changes were not associated with resistance, whereas mutations in the YMDD motif conferred resistance to lamivudine. More importantly, combinations of mutations in the "a-determinant" and the YMDD motif in patients with a severe hepatitis were not only resistant to lamivudine treatment, but showed enhanced replication in vitro in the presence of lamivudine. This observation was confirmed in separate laboratories.

CONCLUSIONS

Severe and fatal hepatitis B infection can occur during lamivudine therapy and may be associated with certain HBV mutants selected during sequential nucleoside and HBIg treatment. The lamivudine-enhanced replication shown by these mutants suggests that continuation of therapy with lamivudine could be deleterious in some patients.

Sensitive enzyme immunoassay for hepatitis B virus core-related antigens and their correlation to virus load

A sensitive enzyme immunoassay (EIA) specific for hepatitis B virus core antigen (HBcAg) and hepatitis B e antigen (HBeAg) was developed. We designated the precore/core gene products as hepatitis B virus (HBV) core-related antigens (HBcrAg). In order to detect HBcrAg even in anti-HBc/e antibody-positive specimens, the specimens were pretreated in detergents. The antibodies are inactivated by this pretreatment and, simultaneously, the antigens are released and the epitopes are exposed. The assay demonstrated 71 to 112% recovery using HBcrAg-positive sera. We observed no interference from the tested anticoagulants or blood components. When the cutoff value was tentatively set at 10(3) U/ml, all healthy control (HBsAg/HBV-DNA negative; n = 108) and anti-HCV antibody-positive (n = 59) sera were identified as negative. The assay showed a detection limit of 4 x 10(2) U/ml using recombinant antigen. Detection limits were compared in four serially diluted HBV high-titer sera. The HBcrAg assay demonstrated higher sensitivity than HBV-DNA transcription-mediated amplification (TMA) or HBeAg radio immunoassay (RIA) in the dilution test. HBcrAg concentrations correlated well with HBV-DNA TMA (r = 0.91, n = 29) and in-house real-time detection-PCR (r = 0.93, n = 47) in hepatitis B patients. On HBeAg/anti-HBe antibody seroconversion panels, the HBcrAg concentration changed in accordance with HBV-DNA levels. HBcrAg concentration provides a reflection of HBV virus load equivalent to HBV-DNA level, and the assay therefore offers a simple method for monitoring hepatitis B patients.

Wild-type and 'a' epitope variants in chronic hepatitis B virus carriers positive for hepatitis B surface antigen and antibody

AIMS

This study aims to examine the genomic variants of the 'a' epitope in chronic hepatitis B virus (HBV) carriers positive for both hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs).

METHODS

Eighteen HBV carriers were studied. Hepatitis B virus (HBV) DNA was extracted and the 'a' epitope region was amplified and sequenced.

RESULTS

Eighteen Chinese asymptomatic HBV carriers were studied. There were 13 patients who were positive for both HBsAg and anti-HBs. Of these, one patient had only wild-type HBV, three had a viral mixture, and five had only 'a' epitope variant HBV. Of the three patients with a viral mixture, all had variants in the less conserved region (123-137). Of the five patients with pure HBsAg mutants, three had variants in the less conserved region while two had variants in the highly conserved region. In this study with a limited number of patients, the serum alanine aminotransferase (ALT) levels were higher in patients with wild-type HBV, compared with those with either 'a' epitope variants or a viral mixture consisting of wild type and variants.

CONCLUSION

Eight of the nine (89%) patients positive for both HBsAg and anti-HBs harbored an 'a' epitope variant. The lower ALT levels seen in patients who had either pure 'a' epitope variant or a mixture of wild type and mutants suggest that a closer monitoring of these 'a' epitope variants should be required, as patients carrying these infectious viral strains may remain asymptomatic.

Real-time PCR for detection and quantitation of hepatitis B virus DNA

A sensitive and reproducible real-time PCR assay based on TaqMan technology was developed for the detection and quantitation of hepatitis B virus (HBV) DNA in serum, and compared with an "in-house" qualitative PCR assay. HBV DNA was measured in 125 serum samples from 76 hepatitis B patients, consisting of 22 patients with an acute infection, 20 patients with a previous history of hepatitis B infection, and 34 patients with a chronic hepatitis B. Four patients with a chronic infection were treated with either an IFN-alpha monotherapy or a combination of IFN-alpha and lamivudine. Twenty-nine sera from healthy individuals and non-hepatitis B patients served as negative controls. The assay was validated by using a 10-fold dilution series of the World Virological Quality Control (VQC) sample containing 3.73 x 10(7) genome equivalents per ml. The detection limit for the real-time PCR was 3.73 x 10(2) genome equivalents per ml (geq/ml), while it was 3.73 x 10(3) geq/ml for the in-house PCR. The real-time PCR assay had an 8-logarithm dynamic range spanning from 10(2) to 10(10) geq/ml. In clinical serum samples, the real-time PCR and the in-house PCR detected HBV DNA in 81% (101/125) and 66% (83/125) of samples, respectively. HBV DNA was not detected among the negative controls by either of these assays. In conclusion, real-time PCR is a sensitive, specific, and a reproducible approach for the detection and quantitation of HBV DNA in clinical serum samples, useful also for monitoring the efficacy of antiviral treatment.

Limitations and improvements of the quantiplex branched-DNA assay in Hepatitis B virus-infected patients receiving lamivudine

The branched DNA (bDNA) assay for hepatitis B virus (Chiron Corporation Emerville, USA) was investigated by application to HBV-infected patients in Taiwan, where the B and C genotypes of hepatitis B virus are most prevalent. The study group included sera with hepatitis B surface antigen (HBsAg) and e antigen (HBeAg); Group 1 (n=70) without treatment; Group 2 (n=28) lamivudine treatment less than 3 months; Group 3 (n=73) lamivudine treatment 3-12 months; Group 4 (n=45) HBeAg-negative sera after 1 year treatment with lamivudine; control group (n=36) HBsAg-negative sera. Comparison of identical-sample results showed a significantly higher coefficient of variation for low-level HBV DNA (<100 MEq/ml) than for high-level (> or =100 MEq/ml), indicating increasing assay inaccuracy uncertainty as the sample HBV DNA concentration decreased. It is thus concluded that low-titered sera should receive special careful pipetting and processing. It was also found that using the relative luminescence of the negative control plus two standard deviations (S.D.) as a new cutoff could promote sensitivity (97.1-->97.1%, 89.3-->100%, 76.7-->84.9%, and 17.8-->22.2% in Groups 1-4, respectively) and specificity (94.4-->97.2%). In summary, the bDNA HBV assay showed only moderate assay performance for samples with low HBV DNA levels. This problem can be improved partially by choosing a new cutoff value based on the relative luminescence of the negative controls in the kit.

Hepatitis virus infections in heart transplant recipients: epidemiology, natural history, characteristics, and impact on survival

BACKGROUND & AIMS

We have observed a high prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection in heart transplant recipients (HTRs). The aim of this study was to assess the epidemiology, natural history, and clinical and biological characteristics of viral hepatitis in HTRs.

METHODS

From 1983 to 1992, 874 patients underwent heart transplantation at the Pitié-Salpêtrière Hospital, Paris, France, 459 of whom qualified for analysis. A total of 140 patients had posttransplantation hepatitis B, C, or non-A-E. Sixty-nine patients developed HBV infection, 49 HCV infection, 11 HBV-HCV coinfection, and 11 non-A-E hepatitis.

RESULTS

HBV was transmitted nosocomially from patient to patient, most likely during endomyocardial biopsies. HCV was mainly transmitted through blood transfusions or the transplanted organ. Clinical and biological findings after 2 years of follow-up showed that 3 patients with an HBV genotype A precore mutant had severe or subfulminant hepatitis and that patients with HBV and HCV infection always progressed to chronicity. In general, patients had mild alanine aminotransferase level increases, a high level of viral replication, and few severe histologic lesions, except for patients infected by precore HBV mutants. Patients coinfected by HBV and HCV tended to have more severe liver lesions. The survival rate 5 years after transplantation in patients with viral hepatitis (HBV, 81%; HCV, 89%; HBV and HCV coinfection, 100%; non-A-E hepatitis, 73%) was similar to that in patients without liver test abnormalities (76%). The actuarial survival curve was also similar in patients with or without liver test abnormalities.

CONCLUSIONS

In our experience, histologic liver lesions do not progress rapidly in patients with post-heart transplant infection caused by HBV or HCV. HBV or HCV infection seems to have little impact on the 5-year survival rate of HTRs.

Decrease of wild-type and precore mutant duck hepatitis B virus replication during lamivudine treatment in white Pekin ducks infected with the viruses

BACKGROUND/AIMS

Lamivudine, an antiviral agent, has been used in the treatment of chronic hepatitis B, but little is known about its effect on intrahepatic replication of hepatitis B virus. We investigated the effect of lamivudine on the replication of wild-type and precore mutant duck hepatitis B virus (DHBV) in the liver and serum of DHBV carrier ducks.

METHODS

Chronic carrier ducks with either wild-type or precore mutant DHBV were treated for 2 weeks with either low-dose (20 mg/kg, p.o., b.i.d.) or high-dose lamivudine (100 mg/kg, p.o., b.i.d.) or were untreated. Serum levels of DHBV DNA were examined serially by slot-blot hybridization. A second group of chronic carrier ducks was treated for 12 weeks with lamivudine (100 mg/kg, p.o., b.i.d.) or was untreated. The amount of DHBV DNA in serum and its various replicative intermediates in the liver were serially examined by slot-, Southern, and Northern blot methods.

RESULTS

In the 2-week treatment study, concentration of DHBV DNA in serum treated with low- and high-dose lamivudine was reduced to 10.8% and 1.1% of the control level in wild-type DHBV carriers, and to 2.3% and 0.48% in precore mutant DHBV carriers, respectively. In the 12-week treatment study, concentration of DHBV DNA in serum at the end of treatment was reduced to <0.65% and <5.36% in wild-type and precore mutant DHBV carriers, respectively. Southern and Northern blot analyses revealed that the various replicative forms of DHBV DNA in the liver were decreased in all treated ducks, but, covalently closed circular DNA and RNA intermediates tended to remain unchanged.

CONCLUSIONS

Our results showed that lamivudine could reduce both wild-type and precore mutant DHBV levels in the liver through inhibition of the reverse transcription step, but complete elimination of the viruses from liver is difficult even by relatively long-term lamivudine monotherapy, suggesting a need for some additional therapy to obtain complete clearance.

Thymosin alpha1 treatment of chronic hepatitis B: results of a phase III multicentre, randomized, double-blind and placebo-controlled study

Previous clinical trials have suggested that thymosin alpha1 (Talpha1), an immunomodulatory peptide, may be effective in the treatment of chronic hepatitis B (CHB). The aim of this study was to determine the efficacy of Talpha1 in a multicentre, placebo-controlled and double-blind study of 97 patients with serum hepatitis B virus (HBV) DNA- and hepatitis B e antigen (HBeAg)-positive CHB. Patients who had been hepatitis B surface antigen (HBsAg) positive for at least 12 months entered a 3-month screening period prior to randomization. Forty-nine patients received Talpha1 (1.6 mg) and 48 patients received placebo, twice weekly for 6 months, and were followed-up for an additional 6 months. At inclusion, both groups were comparable for age, gender, histological grading, and aminotransferase and HBV DNA levels. A complete response to treatment, defined as a sustained serum HBV DNA-negative status (two negative results at least 3 months apart) during the 12-month study, with negative HBV DNA and HBeAg values at month 12, was seen in seven (14%) patients given Talpha1 and in two (4%) patients treated with placebo (P = 0.084). Five (10%) patients given Talpha1 and four (8%) patients given placebo exhibited a delayed response (defined as sustained serum HBV DNA negativity achieved after the 12-month study period with negative HBV DNA and HBeAg values at the last assessment). A total of 12 (25%) patients given Talpha1 and six (13%) patients given placebo showed a sustained loss of HBV DNA with a negative HBeAg value during or following the 12-month study period (P < 0.11). These results do not confirm observations of treatment efficacy reported in other clinical studies.

A hepatitis B virus variant found in the sera of immunised children induces a conformational change in the HBsAg "a" determinant

The emergence of variants in the outer envelope proteins of hepatitis B virus (HBV) are found among individuals vaccinated against HBV and asymptomatic carriers of the infection. For example, children in The Gambia vaccinated against hepatitis B may show serological evidence of breakthrough infections, particularly if anti-HBs antibodies induced by the vaccine are low in titre. A single-point mutation at nucleotide 421 of the S gene is associated with such breakthrough infections. In the present study, the antigenicity of variant HBV S protein expressed as HBsAg particles in a vaccinia virus expression system has been characterised using a panel of monoclonal antibodies directed against linear and conformational determinations of the S protein. A cellular ELISA procedure using expressed antigen in Vero cells revealed differences in reactivity using four of the six antibodies that had been raised against the adw subtype of HBV and recognise conformational epitopes in the a determinant. In two instances, an enhanced reactivity for the variant antigen was found, confirming that point mutations in the a determinant of the S protein between residues 139 and 147 may result in significant changes in conformation. These findings also demonstrate that there are distinct antigenic differences between the vaccine strains of HBsAg/ adw subtype and the predominant HBsAg subtype circulating in West Africa. The implications of this work are that serodiagnosis of HBV infections may be unreliable in populations where there is a possibility of variant HBV infections emerging in the face of increasing herd immunity to HBV as a result of vaccination, particularly using monoclonal antibody-based diagnostic tests. Such variants may play a role in the maintenance of HBV infections in endemic regions.

Branched DNA signal amplification for direct quantitation of nucleic acid sequences in clinical specimens

In this chapter I have reviewed the development of bDNA as a method for quantitation of nucleic acid targets and the application of this technology to the study of infectious diseases and cell biology. The ability to quantify viral nucleic acids in clinical specimens has led to a better understanding of the pathogenesis of chronic viral infections such as HIV-1, HCV, and HBV. The information provided by these methods can also be important in the management of patients with these infections. The prognostic value of a single baseline HIV-1 RNA level rivals that surgical staging procedures for cancer, which are among the most powerfully predictive tests in medicine (Mellors et al., 1996). These methods have been used to assess rapidly the effects of antiviral therapy, which has both expedited the development of antiviral drugs and improved the management of patients with HIV-1 and HCV infections. bDNA has several characteristics that distinguish it from the quantitative target amplification systems, including better tolerance of target sequence variability, more direct measurement of target, simpler sample preparation, and less sample-to-sample variation. However, the first- and second-generation bDNA assays lacked sensitivity compared with the target amplifications systems. The changes incorporated into the third-generation assays have effectively increased the signal-to-noise ratio to such a high level that the analytical sensitivity of system 8 bDNA approaches that of PCR. In theory, bDNA can be made even more sensitive by increasing both the sample volume and the signal-to-noise ratio. Nonspecific hybridization can be further reduced by finding more effective blockers for the solid phase or by redesigning the amplifier molecule or the solid phase itself. The increased sensitivity may create new applications for the technology in filter and in situ hybridization assays.

Efficacy of lamivudine in patients with hepatitis B virus precore mutant infection before and after liver transplantation

OBJECTIVE

Hepatitis B virus (HBV) precore mutant infection is associated with a more severe liver disease and a poorer response to interferon. We evaluated the efficacy and tolerance of lamivudine to induce complete and sustained suppression of viral replication in seven patients infected with HBV precore mutant (HBeAg-/HBeAb+/HBV DNA+) (in three patients mutation at codon 1896 was detected by direct sequencing).

METHODS

Of the seven patients, five had decompensated HBV cirrhosis in a replicative phase and were liver transplant candidates (Group A) and two patients underwent orthotopic liver transplantation (OLT) for HBV liver cirrhosis and developed recurrent HBV infection in the grafted liver (Group B). Lamivudine 100 mg daily was administered orally for a period of 6-75 wk.

RESULTS

After 6-8 wk lamivudine therapy was well tolerated and successfully suppressed HBV replication to an undetectable serum level of HBV DNA by polymerase chain reaction in six patients. In Group A, two patients underwent successful OLT with no evidence of HBV reinfection 2-14 months later. Lamivudine was continued after OLT with no episodes of rejection. Three patients died before a suitable liver could be found (one remained serum HBV DNA+ after 6 wk of lamivudine therapy). In Group B, 9-14 months after lamivudine therapy both patients developed lamivudine resistance (increased liver enzymes, reappearance of serum HBsAg and HBV DNA [by hybridization]). In both patients liver histology had progressed and in both, mutation at codon 552 of the HBV polymerase gene was detected.

CONCLUSIONS

Lamivudine is well tolerated in patients with decompensated liver cirrhosis due to HBV precore mutant infection who are liver transplant candidates. In four patients (80%) potent suppression of viral replication was detected, allowing OLT to be performed. However, post-OLT, a resistant mutant developed under lamivudine therapy. Combination therapy with other antiviral agents should be evaluated to discourage the emergence of lamivudine-resistant mutants.

Quantitative detection of hepatitis B virus by transcription-mediated amplification and hybridization protection assay

We have developed a sensitive and quantitative assay using transcription-mediated amplification and hybridization protection assay for the detection of hepatitis B virus (HBV) DNA in serum. The transcription-mediated amplification was carried out in a single tube. The hybridization protection assay was carried out in a microtiter plate with two probes with different specific activities to obtain a broad detection range. As a result, the assay had a detection range of 5 x 10(3) to 5 x 10(8) genome equivalents (GE)/ml and good quantitative accuracy on a logarithmic scale. A moderately sized manual assay run can be completed within 5 h. Measurements of the amounts of HBV DNA in clinical samples by the assay showed the amounts under various disease conditions to be widely distributed (more than 5 logs, from approximately 5 x 10(3) to 5 x 10(8) GE/ml). It was also shown that the amount of HBV DNA in one chronic hepatitis patient varied widely, with a range of more than 5 logs during long-term monitoring. Our assay has the potential to be used to monitor and determine the prognosis of HBV patients and carriers, especially during interferon treatment.

Colchicine in chronic hepatitis B: a pilot study

RATIONALE

Because of its antifibrotic and anti-inflammatory effects, colchicine has been proposed as a treatment for liver disease. Early in vitro studies have demonstrated that colchicine blocks mitosis in the metaphase and inhibits DNA synthesis.

AIM

A pilot study of hepatitis B virus (HBV)-related/HBV-DNA+ve chronic liver disease.

PATIENTS

Nine biopsy-proven chronic hepatitis patients (three with cirrhosis) entered the study. Two of them were HBeAg+ve and seven were antiHBe+. All patients were HBV-DNA+ve/antiHBc IgM+ve (index values of anti-HBc IgM ranged from 0.370 to 1.200). All of them had a major contraindication to interferon therapy or refused antiviral treatment. The known persistence of positive HBsAg ranged from 2 to 21 years.

METHODS

After informed consent, the patients received 1 mg colchicine a day orally for 5 days-a-week over 6 months. Testing for liver enzymes and viral markers was performed at the baseline and after 3 and 6 months.

RESULTS

None of the patients experienced side-effects during the treatment. The two HBeAg+ve patients seroconverted to anti-HBe with a normalization of AST/ALT during therapy. Among the seven antiHBe+ve patients, four had a complete normalization of transaminases (one patient cleared the HBsAg with seroconversion to anti-HBs). Six of the nine patients were HBV-DNA-ve at the end of therapy and were still negative after 12 months of follow-up.

CONCLUSION

These preliminary results suggest that colchicine might have an antiviral activity in HBV-DNA+ve chronic liver disease, and it could be regarded as an alternative therapy to interferon.

Hepatitis D viremia following orthotopic liver transplantation involves a typical HDV virion with a hepatitis B surface antigen envelope

Patients receiving orthotopic liver transplantation (OLT) because of type D hepatitis frequently exhibit what appears to be an autonomous, or "isolated," hepatitis D virus (HDV) infection following the transplantation, with no evidence of hepatitis B virus (HBV) in the graft or in the serum. These observations have led to the hypothesis that HBV might not always be required for HDV infection, or that HDV could exist as a latent infection until rescued by HBV. Alternatively, an apparently autonomous HDV infection could be explained by coinfection of a small number of hepatocytes with both viruses following transplantation, with a very low level of HBV expression that supports low-level HDV propagation. Our results are consistent with the latter hypothesis. Sensitive polymerase chain reaction (PCR)-based analysis of HBV and HDV viremia in transplantation patients with HDV infection previously characterized as isolated showed that HDV viremia was not independent of HBV viremia. Additional analyses, including PCR amplification, buoyant density analysis in a CsCl gradient, and immunoprecipitation with monoclonal hepatitis B surface antigen antibodies (anti-HBs), indicated that the posttransplant HDV particle is typical: it contains full-length HDV RNA and an envelope of hepatitis B surface antigen (HBsAg) and is not different from that found during the acute and chronic stages of HDV superinfection or coinfection. Moreover, an experimental test of the first hypothesis in chimpanzees did not support the idea that HDV can persist for several weeks as an isolated, latent infection that can be rescued subsequently by HBV. The data indicate, therefore, that latent HDV infection is not a factor in OLT recipients. We conclude that the HDV virion in the posttransplantation setting is typical, and that HDV viremia following OLT requires the helper function of HBV infection.

Hepatitis B: diagnosis, prevention, and treatment

Hepatitis B virus (HBV) infection occurs worldwide and is an important cause of acute and chronic viral hepatitis in the US. In this review, I describe the virus, risk factors for infection, clinical features of infection, results of laboratory tests during infection, and standard and emerging treatment for chronic infection. Although 95% of adult patients recover completely from HBV infection, 90% of children ≤4 years of age develop chronic infection. Active vaccination is highly efficacious.

Review: hepatitis B and liver transplantation

Liver transplantation in hepatitis B virus (HBV)-infected patients is very commonly followed by recurrence of infection in the transplanted liver. Most recipients with HBV recurrence will develop chronic hepatitis that follows a more aggressive course than is seen in non-immuno-compromized subjects and this frequently results in graft failure. The presence of hepatitis B e antigen or significant levels of HBV-DNA in the serum is highly predictive of recurrence and this has led to the view that patients, whose serum is positive for these conventional markers of replication, should be excluded from transplantation. The key to improving the results of transplantation in patients with HBV infection lies in the development of effective strategies to prevent reinfection. High dose anti-HBs immunoglobulin is effective in patients who are coinfected with hepatitis D, those transplanted for fulminant hepatitis and cirrhotic patients who have very low levels of viral replication prior to transplantation. Unfortunately, immunoprophylaxis does not seem to influence the outcome in those patients with higher levels of replication. There are several new orally active nucleoside analogues that and potent inhibitors of hepatitis B replication that may be effective for both the prevention and treatment of recurrent disease. The most promising are lamivudine (2',3',dideoxy,3',thiacytidine) and famciclovir (a guanosine analogue). Both agents have been extensively evaluated in animal models of HBV and have been shown to rapidly suppress viral replication. The initial experience with these agents in liver transplant recipients has been promising and a number of studies are currently underway to determine whether these drugs, used alone or in combination with immunoprophylaxis, are able to prevent recurrence in those patients at highest risk of post-transplant HBV recurrence.

Pre-core mutants of hepatitis B virus in patients receiving immunosuppressive treatment after orthotopic liver transplantation

Orthotopic liver transplantation (OLT) is a possible treatment for acute or chronic liver failure due to hepatitis B virus (HBV) infection, but reinfection of the graft can be a serious complication. The aim of this study was to monitor HBV markers, to analyse pre-core-/core-mutations as well as to identify the viral population causing reinfection after OLT, and to investigate the emergence or disappearance of these mutants in patients receiving immunosuppressive treatment. Fifty-four pre-and posttransplant serum samples of 17 patients were analysed. All patients underwent OLT for HBV-related liver disease and had HBV-DNA before and after OLT. Total DNA was extracted from all sera and a 240 bp fragment comprising the pre-core region of HBV was amplified by polymerase chain reaction (PCR). Pre-core mutants of HBV were determined by direct sequencing of these PCR products and by sequencing of PCR clones. Eight of 17 patients were infected with pre-core wildtype HBV before OLT (group A). Seven of eight patients of group A were reinfected by pre-core wildtype HBV after OLT. In one of eight patients in addition to wildtype HBV a mutant strain (nt. 1899 G-->A) was detected. Nine of 17 patients were infected with pre-core mutant HBV before OLT (group B). Six of nine patients of group B were reinfected with the same mutant population; in one, an additional pre-core mutation emerged; two patients lost pre-core mutant HBV (nt. 1896 and 1899 G-->A). In one of the latter two, a pre-core start-codon mutant (nt. 1816 G-->T), not detectable before OLT, emerged, in the other a nt. 1897 G-->A stop-codon mutant persisted. Five patients of each group were followed-up for more than 24 (25 to 58) months on immunosuppressive therapy. In all five patients of group A, pre-core wildtype of HBV persisted during long-term follow up. Two of five patients of group B were infected stably with a stop-codon HBV-mutant nt. 1896. In three patients, the nt. 1896 stop-codon mutant disappeared during immunosuppressive therapy. However, in one of the latter three, an HBV stop-codon mutant nt. 1897 persisted. In conclusion, most patients who underwent OLT for HBV-related disease were reinfected with the same virus population that existed before OLT. In rare cases, new mutants emerged after OLT or preexisting mutants were lost. During long-term follow-up on immunosuppressive therapy, in the majority of patients pre-core mutants disappeared and wildtype HBV became the predominant virus strain.

Combination low-dose lymphoblastoid interferon and thymosin alpha 1 therapy in the treatment of chronic hepatitis B

This open label study was initiated to assess the safety and efficacy of lymphoblastoid interferon-alpha (IFN-alpha) and thymosin alpha 1 (T alpha 1) in the treatment of 11 patients with chronic hepatitis B, who had failed to respond to standard IFN-alpha 2b therapy, and in four interferon naive patients. These fifteen hepatitis B surface antigen (HBsAg) positive and serum hepatitis B virus (HBV) DNA positive patients were given T alpha 1 (1 mg) subcutaneously (s.c.) on 4 consecutive days. Low-dose lymphoblastoid IFN-alpha (3 MU) was administered intramuscularly (i.m.) on the fourth day. Beginning with the second and for the subsequent 25 weeks, patients self-administered T alpha 1 twice weekly in the morning followed, 12 h later, by 3 million units (MU) lymphoblastoid IFN-alpha. Patients were followed-up for 12 months. Nine (60%) of the 15 patients, including six (55%) of the 11 patients previously treated with IFN-alpha 2b, responded by losing serum HBV DNA and normalizing alanine aminotransferase (ALT) values. Six of the nine responders seroconverted to HBsAg negativity. Significant improvements in the Knodell histological activity index were observed in the responders and no significant adverse effects were observed. Combination low-dose lymphoblastoid IFN-alpha and T alpha 1 treatment may provide a safe and potentially effective therapeutic approach in chronic hepatitis B. These results require confirmation in future randomized controlled studies.

Hepatitis B virus immunopathology

Approximately 5% of the world population is infected by the hepatitis B virus (HBV) which causes a necroinflammatory liver disease of variable duration and severity. Chronically infected patients with active liver disease carry a high risk of developing cirrhosis and hepatocellular carcinoma. The immune response to HBV-encoded antigens is responsible both for viral clearance and for disease pathogenesis during this infection. While the humoral antibody response to viral envelope antigens contributes to the clearance of circulating virus particles, the cellular immune response to the envelope, nucleocapsid and polymerase antigens eliminates infected cells. The class I- and class II-restricted T cell responses to the virus are vigorous, polyclonal and multispecific in acutely infected patients who successfully clear the virus, and they are relatively weak and more narrowly focussed in chronically infected patients who do not. The pathogenetic and antiviral potential of the cytotoxic T lymphocyte (CTL) response to HBV have been demonstrated by the induction of a severe necroinflammatory liver disease following the adoptive transfer of HBV surface antigen-specific CTL into HBV transgenic mice, and by the noncytolytic suppression of viral gene expression and replication in the same animals by a post-transcriptional mechanism mediated by interferon-gamma, tumor necrosis factor-alpha and interleukin-2. The dominant cause of viral persistence during HBV infection is the development of a weak antiviral immune response to the viral antigens. While neonatal tolerance probably plays an important role in viral persistence in patients infected at birth, the basis for poor responsiveness in adult onset infection is not well understood and requires further analysis. Viral evasion by epitope inactivation and T cell receptor antagonism may contribute to the worsening of viral persistence in the setting of an ineffective immune response, as can the incomplete down-regulation of viral gene expression and the infection of immunologically privileged tissues. Chronic liver cell injury and the attendant inflammatory and regenerative responses create the mutagenic and mitogenic stimuli for the development of DNA damage that can cause hepatocellular carcinoma. Elucidation of the immunological and virological basis for HBV persistence may yield immunotherapeutic and antiviral strategies to terminate chronic HBV infection and reduce the risk of its life-threatening sequellae.

Prevalence of precore-defective mutant of hepatitis B virus in HBV carriers

Two hundred and seventy-three serum specimens from hepatitis B virus (HBV) carriers were examined for the presence of a characteristic one point mutation at nucleotide (nt) 1896 from the EcoRI site of the HBV genome in the precore region (the preC mutant) using restriction fragment length polymorphism (RFLP) analysis. This assay approach could detect preC mutants or wild-type sequences when either form constituted more than 10% of the total sample. Overall, 65.5% (76/116) of HBeAg-positive carriers had only the preC wild-type. All HBeAg-positive asymptomatic carriers (n = 14) had only the preC wild-type. In patients with chronic hepatitis B and in anti-HBe-positive asymptomatic carriers, increased prevalence of the preC mutant was associated with the development of anti-HBe antibodies and normalization of the serum alanine aminotransferase concentration. Furthermore, 27 (29.0%) of 93 HBeAg-negative carriers had unexpectedly preC wild-type sequences only. Direct sequencing of the HBV precore region of HBV specimens from 24 patients revealed no mutation at nt 1896, supporting the specificity of the RFLP analysis. These results suggest that RFLP analysis was accurate for the detection of the preC mutation and that the absence of serum HBeAg cannot be explained solely by the dominance of the preC mutant.

Genomic variations in the hepatitis B core gene: a possible factor influencing response to interferon alfa treatment

BACKGROUND/AIMS

Interferon treatment causes a sustained loss of virus replication only in a proportion of patients with chronic hepatitis B. This study investigated whether genomic variations in the precore/core gene of hepatitis B virus affect the response to interferon alfa.

METHODS

The precore/core region was sequenced in 46 serum samples obtained before, during, and after interferon treatment of 12 patients.

RESULTS

In 23 samples from 7 responders (group A), there were 24 missense mutations, whereas in 23 samples from 5 patients who did not respond or relapsed after treatment (group B), there were 141 missense mutations (P < 0.001). All group B patients had cirrhosis, but only 2 of 7 patients in group A had cirrhosis (P = 0.026). Substitutions in amino acids 21-27 of the core protein, known to diminish HLA-A2-restricted cytotoxic T-cell function, were found in all nonresponders but in none of the responders. No significant changes occurred in the precore/core region in responders after seroconversion to antibody to hepatitis B e antigen, but multiple variations persisted in group B during treatment and new mutations appeared with the relapse of hepatitis.

CONCLUSIONS

Specific mutations in the core protein that can interfere with T-cell function occur frequently in patients with advanced chronic hepatitis B and may affect the response to interferon.

Hepatitis B virus precore mutant infection is associated with severe recurrent disease after liver transplantation

The factors that predispose patients undergoing liver transplantation for hepatitis B virus (HBV) disease to severe recurrence of infection are unclear. In this study we examined the effect of pretransplantation infection with HBV and precore variant strains of HBV on posttransplantation outcome and allograft histology in 24 patients who survived more than 3 months after liver transplantation. Based on pretransplantation serum HBV DNA status as detected by the polymerase chain reaction (PCR) and direct sequencing, the 24 patients could be assigned to three groups. In group 1 there were 4 patients HBV DNA-negative before transplantation and none of these patients suffered recurrence of infection posttransplantation. In group 2, of 10 patients with pretransplantation infection with wild-type virus, 7 became reinfected, and 1 of these developed HBV-related graft failure. In group 3, 9 of 10 patients infected with precore mutant HBV strains became reinfected. However, in contrast to the patients in group 2, 7 patients in group 3 developed HBV-related graft loss, and 5 of these patients had fibrosing cholestatic hepatitis (FCH). These results indicate that infection with precore mutant strains of HBV predisposes a patient to early graft loss following transplantation.

A Viral Mechanism in Acute Exacerbations of Chronic Type B Hepatitis: Hepatitis B Virus Reinfection and Subsequent Reactivation of Two Viral Strains

Chronic hepatitis B virus (HBV) infections are frequently associated with exacerbations of hepatitis of which the majority are due to reactivation of viral activity. Variation in a viral genome during persistent infection has been shown to be a possible cause for reactivation. In this study, we have found another possible mechanism. HBV in a patient with repeated exacerbations was isolated at six different times during follow-up and was characterized by polymerase chain reaction and DNA sequencing. The first episode of exacerbation was accompanied with increased replication of an HBV strain. The second episode, however, was associated with the sudden appearance of an HBV strain that displayed enough sequence variations to warrant the designation as a separate strain. The results suggested a reinfection event by another independent HBV. Subsequent exacerbations were then related to coactivation of both viral strains. These observations provide significant information toward understanding the acute exacerbations of chronic type B hepatitis. Copyright 2001 S. Karger AG, Basel

Different prevalence of precore mutants in five members of a hepatitis-B-virus-infected family: evidence for a precore variant type in an asymptomatic anti-HBs patient

Chronic active hepatitis B (CAH-B), anti-HBe (+) has been associated with a hepatitis B virus variant carrying a stop codon at the distal pre-C region that prevents HBeAg synthesis. We analyzed the HBV DNA pre-C region in five members of a Turkish family. The mother presented an anti-HBe (+) CAH-B and the four children different hepatitis B virus serological and clinical profiles. The pre-C region was analyzed by cloning after DNA amplification in sera and peripheral blood mononuclear cells. A method for rapid screening of a large number of cloned polymerase chain reaction products was developed for the presence of the most frequent pre-C mutations (G to A substitution at nucleotide position 1896 and 1899). At least 60 independent clones were tested for each patient by selective oligonucleotide hybridization using non-mutated (M0), one (M1) and two (M2) point-mutated probes. Results were confirmed by sequencing. The mutation 1896 was present in 91% of DNA clones from the mother. The same mutation was also found in 85% of the clones in the youngest child (D), but in less than 10% of the clones from children A and C. Only the pre-C wild-type strain was observed in child B. X gene deletions (3 to 20 nt) were also present in some clones from the mother and children A, B and C. No significant difference between serum and peripheral blood mononuclear cells concerning the viral population was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative biology and pathogenesis of AIDS and hepatitis B viruses: related but different

AIDS (HIV) and hepatitis B viruses are remarkably similar in their sharing of reverse transcription, in their ancestral origins and common genetic elements, and in their modes of transmission. Both are hypermutable and exist as quasispecies due primarily to errors in reverse transcription, though there is severe restriction in the replicative competence of most hepatitis B mutants. They differ in the lack of an integrase in hepatitis B virus and in their pathogenesis in the infected host. HIV survives mainly by antigenic variability, immune evasion, and impairment of immune function though viral regulatory control elements seek to restrict fatal damage to the host. Hepatitis B virus survives primarily by mutation of e antigen/core genes that directly obviates cytotoxic T cell destruction of infected liver cells, or indirectly limits destruction of infected cells through induction of anergy in the cytotoxic T cell response. Most persons infected with hepatitis B virus recover completely while recovery from HIV infection is rare if ever. Hepatitis B is highly preventable by vaccine while HIV vaccine is still seeking a meaningful immunoprophylactic target. AIDS and hepatitis B represent an extreme example, among the viruses of man, in their close similarities but distinct differences. In depth details and perspectives are presented in this review.

Viral hepatitis in children with renal disease

Specific and sensitive diagnostic tests are now available to identify type A, B, C, D and E hepatitis. Hepatitis A and E which cause only acute, very rarely fulminant, hepatitis are spread largely by the faecal-oral route, having a brief viraemic phase. Hepatitis B, C and D which are transmitted parenterally and via secretions are often associated with chronic viraemia. Patients with chronic renal disease are at particular risk. Impaired immunity due to disease or drugs increases the propensity to develop a chronic carrier state which may progress to cirrhosis and hepatocellular carcinoma. Limited reports indicate that hepatitis C infection may cause cirrhosis more rapidly than hepatitis B. The emergence of mutants to both hepatitis B and C is a cause for concern. Treatment with interferon is of limited efficacy. Screening of blood products for viral markers and prudent handling of potentially infected materials to avoid contamination of damaged skin or mucous membrane are the best strategies to prevent infection. Hepatitis B vaccination of all newborns, young adolescents and those at risk is the most effective means of reducing the carrier frequency.

Comparison of methods for detection of hepatitis B virus DNA

We compared the performance of four assays for detection of hepatitis B virus (HBV) DNA: the PCR; the branched DNA hybridization assay (Chiron); and two hybridization assays that use liquid hybridization (Abbott) or direct membrane hybridization (MH). Testing 109 random hepatitis B surface antigen-positive patient samples, the percentages found to be HBV DNA positive among 30 hepatitis B e antigen (HBeAg)-positive samples and 79 HBeAg-negative samples were as follows: PCR, 100 and 90%; Chiron, 73 and 25%; Abbott, 67 and 13%; and MH, 40 and 8%. In six hepatitis B surface antigen-positive, HBeAg-negative samples, all three hybridization assays detected HBV DNA. Testing dilutions prepared from the Eurohep HBV DNA standards, the detection limits of the assays appeared to be the following: PCR, 2.5 x 10(2) HBV genomes per ml; Chiron, 2.5 x 10(6) genomes per ml; and Abbott and MH, 2.5 x 10(7) genomes per ml. HBV DNA levels in the dilution series, as reported by the Chiron and MH assays, were, on average, 2 times higher than calculated; the Abbott results were, on average, 19 times lower than calculated. We concluded that high levels of HBV DNA and the presence of HBeAg do not necessarily coincide, that the application of hybridization assays is limited to the monitoring of relatively high levels of HBV DNA, and that further standardization of quantitative HBV DNA assays is necessary to facilitate comparison of HBV DNA levels.

Interferon therapy for the anti-HBe positive form of chronic hepatitis B

Two distinct serologic types of chronic hepatitis B have been identified, namely the "classical" HBeAg positive form and the "atypical" HBeAg negative, anti-HBe positive variant which is due to infection by a mutant HBV having a pre-core stop codon that makes the virus unable to produce HBeAg. The anti-HBe positive form is currently the prevalent type of chronic hepatitis B in the Mediterranean area, being associated with a more severe clinical course compared to HBeAg positive cases. The response to interferon therapy in patients with anti-HBe positive chronic hepatitis B has been recently investigated in control trials. These studies have shown that normalization of ALT with efficient suppression of virus activity can be achieved in 50-80% of patients while treated with interferon alpha indicating that also the pre-core mutant of HBV is sensitive to the antiviral effect of interferon. However, reactivation of hepatitis occurs in a variable percentage of initial responders when interferon is stopped. The probability of reactivation increases when the disease is of long duration, when cirrhosis is present and particularly if the pre-core mutant of HBV has become the predominant type of circulating virus, indicating that this HBV variant is more resistant to immunoclearance compared to wild type HBV.

High levels of viral replication during acute hepatitis B infection predict progression to chronicity

To assess the pattern of development of serologic markers during acute hepatitis B, levels of HBsAg, HBeAg, and hepatitis B virus (HBV) DNA were assayed in stored serum samples obtained sequentially from 12 subjects infected with HBV during experimental studies conducted in the 1950s. Six patients developed acute self-limited hepatitis, three developed chronic hepatitis, and three had an asymptomatic infection without HBsAg. HBsAg was the first serologic marker detected (mean = 52 days after exposure), followed by HBeAg (62 days) and HBV DNA (72 days). Peak HBsAg levels occurred before onset of symptoms and correlated with peak titers of HBeAg and HBV DNA. Patients who developed chronic hepatitis had higher peak levels of viral markers than those with self-limited disease: HBsAg (30 versus 5.4 micrograms/ml), HBeAg (1:2,000 versus 1:60 titer) and HBV DNA (3,192 versus 444 pg/ml). Thus, chronic HBV infection is characterized by high levels of viral replication appearing early during the acute phase of infection.