Risk of hepatitis B surface antigen seroreversion after allogeneic hematopoietic SCT

Allogeneic hematopoietic SCT (HSCT) increases the risk of hepatitis B virus (HBV) reactivation in hepatitis B surface antigen (HBsAg) carriers but the incidence, risk factors and course of HBV reactivation after HSCT in HBsAg-negative/anti-hepatitis B core antigen (anti-HBc)-positive recipients are not well known. A total of 50 HBsAg-negative/anti-HBc-positive HSCT recipients with onco-hematological diseases, underwent sequential clinical and laboratory examinations, including serum HBsAg, during follow-up. Serum HBV DNA collected at HSCT was retrospectively amplified by a sensitive PCR assay. During 17 months of follow-up, six (12%) patients had seroreverted to HBsAg, 7-32 months after HSCT, with 1- and 5-year cumulative rates of 13 and 22%. HBsAg seroreversion was associated with serum HBeAg higher than 8 log₁₀ copies per ml HBV DNA and a 1.5 to 36 fold increase of serum alanine aminotransferase leading to HBeAg-positive chronic hepatitis B in all patients. Patients with chronic onco-hematological disease and long-lasting immunosuppression following HSCT had a higher risk of HBsAg seroreversion independently of serum HBV DNA levels at HSCT. HBsAg-negative/anti-HBc-positive HSCT recipients with chronic onco-hematological disease carry a significant risk of HBsAg seroreversion and HBeAg-positive chronic hepatitis B, independently of serum levels of HBV DNA at transplantation.

European multicenter evaluation of high-density DNA probe arrays for detection of hepatitis B virus resistance mutations and identification of genotypes

Polymorphisms along the hepatitis B virus (HBV) genome have an impact on disease outcome, sensitivity to antiviral treatment, escape from vaccination, and laboratory diagnosis. We have designed a diagnostic tool based on duplex amplification of the whole HBV genome and a high-density DNA chip designed to detect 245 mutations, 20 deletions, and 2 insertions at 151 positions and to determine the genotype of the virus in serum. Assay performances were evaluated with 170 samples, characterized by determination of viral load and sequencing of the Pol, S, and precore genes and the basal core promoter. One hundred fifty-three samples (90%) could be amplified and analyzed by the chip. Only two samples with more than 10(3) genome copies/ml could not be analyzed. Genotype had no impact on analytical sensitivity. Reproducibility studies showed no difference between repeats for codon and genotype determination. Genotype determination by sequencing and the chip were concordant in 148 of 151 samples. Twelve thousand one hundred sixty-one codons were analyzed by both techniques. Only 89.4% could be determined by sequencing, and among the remaining 11,335 codons, 92.8% were identical by sequencing and the chip. Failures to identify an amino acid by the chip were mainly due to reduced hybridization efficiency attributed to unexpected polymorphisms. Optimization of the chip-based reagent for the analysis of the HBV genome is ongoing. This first evaluation showed that DNA chip technology can provide important information in relation to the clinical management of chronic hepatitis B.

In vitro characterization of the anti-hepatitis B virus activity and cross-resistance profile of 2',3'-dideoxy-3'-fluoroguanosine

The fluorinated guanosine analog 2',3'-dideoxy-3'-fluoroguanosine (FLG) was shown to inhibit wild-type (wt) hepatitis B virus (HBV) replication in a human hepatoma cell line permanently expressing HBV. Experiments performed in the duck model of HBV infection also showed its in vivo antiviral activity. In this study, we investigated the mechanism of inhibition of FLG on HBV replication and its profile of antiviral activity against different HBV or duck hepatitis B virus (DHBV) drug-resistant mutants. We found that FLG-triphosphate inhibits weakly the priming of the reverse transcription compared to adefovir-diphosphate in a cell-free system assay allowing the expression of an enzymatically active DHBV reverse transcriptase. It inhibits more potently wt DHBV minus-strand DNA synthesis compared to lamivudine-triphosphate and shows a similar activity compared to adefovir-diphosphate. FLG-triphosphate was most likely a competitive inhibitor of dGTP incorporation and a DNA chain terminator. In Huh7 cells transiently transfected with different HBV constructs, FLG inhibited similarly the replication of wt, lamivudine-resistant, adefovir-resistant, and lamivudine-plus-adefovir-resistant HBV mutants. These results were consistent with those obtained in the DHBV polymerase assay using the same drug-resistant polymerase mutants. In conclusion, our data provide new insights in the mechanism of action of FLG-triphosphate on HBV replication and demonstrate its inhibitory activity on drug-resistant mutant reverse transcriptases in vitro. Furthermore, our results provide the rationale for further clinical evaluation of FLG in the treatment of drug-resistant virus infection and in the setting of combination therapy to prevent or delay drug resistance.

Effect of a combination of clevudine and emtricitabine with adenovirus-mediated delivery of gamma interferon in the woodchuck model of hepatitis B virus infection

Our aim was to evaluate the antiviral effect of a combination of two nucleoside reverse transcriptase inhibitors, emtricitabine (FTC) and clevudine (L-FMAU), with the addition of an adenovirus-driven delivery of recombinant gamma interferon (IFN-gamma) in the woodchuck model of hepatitis B virus infection. Six woodchuck hepatitis virus (WHV)-infected woodchucks received L-FMAU (10 mg/kg) plus FTC (30 mg/kg) intraperitoneally for 8 weeks; six other animals received in addition an intravenous injection of a recombinant adenovirus vector expressing woodchuck IFN-gamma (Ad-IFN) at weeks 4 and 8. In the control group, two animals received Ad-IFN alone, two received adenovirus vector expressing the green fluorescent protein reporter gene, and one remained untreated. In less than 2 weeks, all woodchucks that received L-FMAU plus FTC showed a rapid and marked inhibition of viral replication, with a 4-log(10) drop in serum WHV DNA. In two animals, viremia remained suppressed for several months after the end of treatment. Similarly, a dramatic decrease in intrahepatic replicative intermediates of viral DNA was observed in the L-FMAU/FTC-treated groups. The additional administration of Ad-IFN led to increased inflammation in the liver but did not enhance the antiviral effect of the L-FMAU/FTC combination. In conclusion, therapies combining L-FMAU and FTC in WHV-infected woodchucks resulted in a potent and sustained antihepadnaviral effect both in the liver and in the blood circulation. However, no extra benefit of adding IFN-gamma gene transduction to the L-FMAU/FTC combination could be detected.

Animal models for the study of HBV infection and the evaluation of new anti-HBV strategies

BACKGROUND

Our aim was to evaluate the anti-HBV activity of a novel L-nucleoside analog, 2',3'-dideoxy-2',3'-didehydro-beta-L-5-fluorocytidine (beta-L-Fd4C), in study models of HBV infection.

METHOD

Its mechanism of action was evaluated on the in vitro expressed duck HBV (DHBV) reverse transcriptase and in primary hepatocyte cultures of duck and human origin. The capacity of antiviral therapy to clear viral infection was analyzed in vivo in the duck and woodchuck models.

RESULTS

beta-L-Fd4C-TP exhibited a more potent inhibitory effect on the RT activity of the DHBV polymerase than other cytidine analogs (lamivudine-TP, ddC-TP, beta-L-FddC-TP). In primary duck hepatocyte cultures, beta-L-Fd4C exhibited a long-lasting inhibitory effect on viral DNA synthesis but could not clear viral cccDNA. In vivo treatment with beta-L-Fd4C in infected ducklings and woodchucks, induced a greater suppression of viremia and intrahepatic viral DNA synthesis than with lamivudine. However, covalently closed circular DNA persistence explained the relapse of viral replication after treatment withdrawal. Viral spread was strongly reduced in the case of early therapeutical intervention, but the number of infected cells did not decline when therapy was started during chronic infection. Liver histology analysis showed a decrease in the inflammatory activity of chronic hepatitis while no ultrastructural modification of liver cells was observed in electron microscopy studies. Furthermore, in human primary hepatocyte cultures, beta-L-Fd4C induced a significant inhibition of HBV DNA synthesis.

CONCLUSION

beta-L-Fd4C is a potent inhibitor of hepadnavirus RT and inhibits viral DNA synthesis in hepatocytes both in vitro and in vivo. These experimental studies allowed as to show that beta-L-Fd4C is a promising anti-HBV agent. Combination therapy should be evaluated to eradicate viral infection.

Successful combination therapy of polyarteritis nodosa associated with a pre-core promoter mutant hepatitis B virus infection

BACKGROUND/AIMS

To describe the clinical and virological evolution of a polyarteritis nodosa (PAN) case associated with a hepatitis B virus (HBV) pre-core promoter mutant infection that was successfully treated with plasma exchanges, corticosteroids, and interferon alpha (IFN-alpha).

METHODS

Viral markers were used, including HBV DNA quantified by the branched DNA assay and detected by PCR, the HBV genome sequence, pre-S1Ag and anti-HBC IgM which were studied throughout the treatment period and the entire follow-up in the serum, while the presence of virus in extrahepatic sites was detected by immuno-staining.

RESULTS

The patient was infected with a typical pre-core promoter mutant harboring four point mutations. Pre-S1Ag was cleared rapidly from serum, most likely via the formation of immune complexes since HBV DNA declined more progressively. Viral infection was then cleared after a second episode of hepatocyte lysis. This was accompanied by a recovery from all clinical manifestations.

CONCLUSIONS

The favorable treatment outcome observed in this first case of pre-core promoter HBV mutant associated PAN underlines that combination therapy based on IFN-alpha can clear pre-core promoter HBV infection and cure PAN. It also provides new insight in the pathogenesis of HBV associated PAN.

Antiviral activity of beta-L-2',3'-dideoxy-2',3'-didehydro-5-fluorocytidine in woodchucks chronically infected with woodchuck hepatitis virus

The L-nucleoside analog beta-L-2',3'-dideoxy-2',3'-didehydro-5-fluorocytidine (beta-L-Fd4C) was first shown to exhibit potent activity against hepatitis B virus (HBV) in tissue culture and then to significantly inhibit viral spread during acute infection in the duck HBV model (F. Le Guerhier et al., Antimicrob. Agents Chemother. 44:111-122, 2000). We have therefore examined its antiviral activity in a mammalian model of chronic HBV infection, the woodchuck chronically infected with woodchuck hepatitis virus (WHV). Side-by-side comparison of beta-L-Fd4C and lamivudine administered intraperitoneally during short-term and long-term protocols demonstrated a more profound inhibition of viremia in beta-L-Fd4C-treated groups. Moreover, beta-L-Fd4C induced a marked inhibition of intrahepatic viral DNA synthesis compared with that induced by lamivudine. Nevertheless, covalently closed circular (CCC) DNA persistence explained the lack of clearance of infected hepatocytes expressing viral antigens and the relapse of WHV replication after drug withdrawal. Liver histology showed a decrease in the inflammatory activity of chronic hepatitis in woodchucks receiving beta-L-Fd4C. An electron microscopy study showed the absence of ultrastructural changes of hepatic mitochondria, biliary canaliculi, and bile ducts. However, a loss of weight was observed in all animals, whatever the treatment, as was a transient skin pigmentation in all woodchucks during beta-L-Fd4C treatment. There was no evidence that lamivudine or beta-L-Fd4C could prevent the development of hepatocellular carcinoma with the protocols used. These results indicate that beta-L-Fd4C exhibits a more potent antiviral effect than lamivudine in the WHV model but was not able to eradicate CCC DNA and infected cells from the liver at the dosage and with the protocol used.

Duck hepatitis B virus polymerase gene mutants associated with resistance to lamivudine have a decreased replication capacity in vitro and in vivo

BACKGROUND/AIMS

Hepatitis B virus mutants of the polymerase gene are frequently selected during lamivudine therapy for chronic hepatitis B. To study the biology of these mutants, we analyzed their replication capacity in the duck hepatitis B virus (DHBV) infection.

METHODS

The B and C domain polymerase mutants corresponding to the clinical isolates were engineered by site directed mutagenesis in the DHBV genome in different expression vectors.

RESULTS

The study of the enzymatic activity of the mutated viral polymerase polypeptides analyzed in a cell free system demonstrated a lower priming activity and a decreased capacity of elongation of viral minus strand DNA that was consistent with the lower replication capacity of these mutants in transfected leghorn male hepatoma cells compared to wild type genome. These mutants had a lower replication capacity in primary hepatocytes and in in vivo transfected ducklings. Although resistant to lamivudine, these mutants remained sensitive to PMEA.

CONCLUSION

YMDD mutants of the DHBV reverse transcriptase have a decreased replication capacity both in vitro and in vivo, and are not cross-resistant to PMEA. These results may be important to design new antiviral strategies to combat the replication of the lamivudine resistant viral strains.

Early detection of viral resistance by determination of hepatitis B virus polymerase mutations in patients treated by lamivudine for chronic hepatitis B

We have analyzed the molecular dynamics of emergence of drug-resistant strains in patients receiving lamivudine therapy for chronic hepatitis B. Twenty consecutive patients with lamivudine resistance were studied (13 hepatitis B e antigen [HBeAg]-positive patients and 7 HBe antibody [anti-HBe]-positive patients). Determination of viral genotype, precore mutants, and polymerase gene mutants (L528M, M552V, M552I) was performed using the research version of Lipa-HBV. Quantitative analysis of HBV DNA was performed using both branched DNA (bDNA) and polymerase chain reaction (PCR) assays. Polymerase mutants (genotypic resistance) were found in 16 of 20 patients. Genotypic resistance was detected earlier than the phenotypic resistance (P =.004). Quantitative PCR allowed detection of viral DNA throughout the entire study period in 16 of 20 patients. Analysis of pretreatment variables showed that high alanine transaminase (ALT) levels (>3 x the upper limit of normal [ULN]) was associated with a more rapid selection of drug-resistant mutants (P =.027) and a high hepatitis B virus (HBV) DNA level (>1,497 Meq/mL, bDNA) with a more rapid occurrence of phenotypic resistance (P =.04). At the time of viral breakthrough, the mean serum HBV-DNA values were not different from the pretreatment values (P =.37). ALT levels were higher in anti-HBe-positive patients compared with pretreatment values and to HBeAg-positive patients (P =.01). In 8 patients, antiviral therapy was modified after viral breakthrough, with the introduction of famciclovir and/or interferon alfa. Viral DNA became undetectable by bDNA in 3 patients who received interferon. Our results suggest that genotypic assays for polymerase mutant detection and quantitative determination of viremia with highly sensitive assay are warranted for an optimal monitoring of antiviral therapy of chronic hepatitis B.

Rapid detection of genotypes and mutations in the pre-core promoter and the pre-core region of hepatitis B virus genome: correlation with viral persistence and disease severity

BACKGROUND/AIMS

We aimed to clarify the clinical relevance of hepatitis B virus pre-core mutant detection in patients with chronic hepatitis B using a newly developed assay.

METHODS

Viral genotypes and pre-core mutations were studied in relation to viral persistence and liver disease severity using INNO-LiPA methodology. The study group included 151 patients with chronic hepatitis B, 85 positive for HBeAg (group I) and 66 positive for anti-HBe (group II).

RESULTS

The prevalence of viral genotypes in group I was: 64% A, 1% B, 15% C, 19% D, 0% E, 0% F and in group II: 39% A, 0% B, 2% C, 56% D, 2% E, 2% F (p<0.001). The prevalence of mutations at pre-core codon 28 (M2) was lower in group I (5%) than in group II (64%) (p<0.001). The prevalence of pre-core promoter mutations was also lower in group I (21%) than in group II (61%) (p<0.001). M2 mutations were more frequently detected in genotype D than in genotype A (p<0.001), while the other mutations were not influenced by viral genotype. Serum HBV DNA levels were significantly lower in group II versus group I (p<0.001), and in patients with any of the pre-core mutations versus wild-type sequence (p<0.01). Although cirrhosis was more frequent in group II (37%) versus group I (22%) and in patients with either one of the pre-core mutation (31%) versus wild-type sequence (25%), there was no statistical difference in liver severity assessed by ALT levels and Knodell score.

CONCLUSION

Pre-core mutants, whose molecular pattern is strongly dependent on viral genotypes, are associated with viral persistence in anti-HBe positive patients with ongoing chronic hepatitis B. The availability of this rapid assay should allow a precise monitoring of viral pre-core mutants during the course of chronic hepatitis B.

Evolution of hepatitis B virus polymerase gene sequence during famciclovir therapy for chronic hepatitis B

Prolonged administration of nucleoside analogues for chronic hepatitis B may result in the emergence of hepatitis B viral polymerase mutants. To gain insight into the mechanism involved in the virus's resistance to famciclovir, the amino acid sequences of the terminal protein and reverse-transcriptase (RT) domains of the viral polymerase were determined during therapy among 28 patients. The antiviral response was independent of viral genotypes, and nonresponse to famciclovir was associated with a complex variability of the RT domain. No mutation in the YMDD motif was observed, whereas an L528M mutation was clearly selected by famciclovir treatment in 2 patients, as well as 14 novel mutations in 7 patients. Clone sequence analysis of the RT domains of patients undergoing retreatment with famciclovir and/or lamivudine showed the selection of a preexisting drug-resistant mutant in one case and indicated that sequential antiviral therapy may allow the rapid selection of resistant strains.

Persistence of viral replication after anti-HBe seroconversion during antiviral therapy for chronic hepatitis B

BACKGROUND/AIMS

Hepatitis B virus genome mutants may be selected during the immune-mediated clearance of infection or during long-term nucleoside analog administration and may escape both antiviral pressures. The pattern of anti-HBe seroconversion was analyzed in patients receiving new nucleoside analogs, lamivudine or famciclovir, in comparison with patients treated with interferon alpha.

METHODS

Eighteen consecutive patients who seroconverted to anti-HBe were included in the study. Serial serum samples were studied with the quantitative determination of HBV DNA by the branched DNA assay (Chiron) and by a quantitative PCR assay (Roche diagnostics), determination of pre-S1 Ag, the genetic analysis of the viral genome with the determination of pre-core promoter or pre-core region mutations with a line probe assay (Innogenetics) and, in selected samples of polymerase gene mutations.

RESULTS

The quantitative PCR assay was found to be more sensitive than the bDNA assay, allowing a 25-log decrease in viral DNA levels to be demonstrated after anti-HBe seroconversion. Viral persistence after anti-HBe seroconversion induced by interferon, lamivudine or famciclovir, was often associated with circulating HBV genomes harboring mutations in the precore promoter. The clinical significance of these findings was demonstrated by the observation of reversion to HBeAg in two patients treated with interferon and one with lamivudine.

CONCLUSION

Persistence of significant levels of viremia that are not detected by the branched DNA assay may be observed after anti-HBe seroconversion. A precise monitoring of viremia levels with more sensitive assays and HBV mutant strains is warranted in patients undergoing antiviral therapy.

Characterization of the antiviral effect of 2',3'-dideoxy-2', 3'-didehydro-beta-L-5-fluorocytidine in the duck hepatitis B virus infection model

A novel L-nucleoside analog of deoxycytidine, 2',3'-dideoxy-2', 3'-didehydro-beta-L-5-fluorocytidine (beta-L-Fd4C), was recently shown to strongly inhibit hepatitis B virus (HBV) replication in the 2.2.15 cell line. Therefore, its antiviral activity was evaluated in the duck HBV (DHBV) infection model. Using a cell-free system for the expression of the DHBV polymerase, beta-L-Fd4C-TP exhibited a concentration-dependent inhibition of dCTP incorporation into viral minus-strand DNA with a 50% inhibitory concentration of 0.2 microM which was lower than that of other tested deoxycytidine analogs, i.e. , lamivudine-TP, ddC-TP, and beta-L-FddC-TP. Further analysis showed that beta-L-Fd4C-TP is likely to be a competitive inhibitor of dCTP incorporation and to cause premature DNA chain termination. In primary duck hepatocyte cultures infected in vitro, beta-L-Fd4C administration exhibited a long-lasting inhibitory effect on viral DNA synthesis but could not clear viral covalently closed circular DNA (CCC DNA). Results of short-term antiviral treatment in experimentally infected ducklings showed that beta-L-Fd4C exhibited the most potent antiviral effect, followed by beta-L-FddC, lamivudine, and ddC. Longer administration of beta-L-Fd4C induced a sustained suppression of viremia (>95% of controls) and of viral DNA synthesis within the liver. However, the persistence of trace amounts of viral CCC DNA detected only by PCR was associated with a recurrence of viral replication after drug withdrawal. In parallel, beta-L-Fd4C treatment suppressed viral antigen expression within the liver and decreased intrahepatic inflammation and was not associated with any sign of toxicity. Our data, therefore, demonstrate that in the duck model of HBV infection, beta-L-Fd4C is a potent inhibitor of DHBV reverse transcriptase activity in vitro and suppresses viral replication in the liver in vivo.

[Hepatitis B virus reactivation after allogeneic bone marrow transplantation in a patient previously cured of hepatitis B]

The presence of antibodies to HBs and HBc antigens indicates previous infection with hepatitis B virus but does not necessarily reflect viral clearance. Immunosuppression such as that observed in patients with bone marrow transplantation may be responsible for viral reactivation followed by acute exacerbation after withdrawal of immunosuppressive therapy. We report a case in a patient with natural immunity to hepatitis B who had undergone allogenic bone marrow transplantation with an identical sibling donor one year before for the chronic myelogenous leukemia in the first chronic phase. Ganciclovir treatment resulted in control of hepatitis virus B replication and in biochemical remission. We suggest that prevention relies on serological evaluation and therapy with active or passive immunisation or antiviral drugs in case of a rapid decline of anti-HBs Ab titers to undetectable levels.

Transient selection of a hepatitis B virus polymerase gene mutant associated with a decreased replication capacity and famciclovir resistance

Prolonged therapy for chronic hepatitis B (HBV) with nucleoside analogs may result in the emergence of HBV mutants resistant to antivirals. Here, we describe the transient selection of an HBV polymerase gene mutant that was associated with viral persistence in an immune competent patient treated with famciclovir. Viral polymerase gene sequence was analyzed directly on polymerase chain reaction (PCR) products and also after cloning. The results showed the transient selection of a V542I mutant in the C domain of the viral polymerase. This mutation was associated with a stop codon at amino acid position 199 in the overlapping S gene. The mutated sequence was subcloned in a vector expressing the entire HBV pregenome to study its replication capacity after transient transfection in cultured hepatoma cells. The results showed that the V542I mutant has a decreased replication capacity compared with wild type virus and does not produce HBsAg. The sensitivity of the V542I mutant to penciclovir, the active metabolite of famciclovir, was further studied in tissue culture. This mutant was shown to be resistant to penciclovir, but remained sensitive to lamivudine, as was subsequently observed in vivo. These findings indicate that a prolonged administration of famciclovir may allow for the selection of HBV polymerase gene mutants in immune competent patients. The impaired replication capacity of this V542I mutant may have contributed to the absence of outgrowth of this viral strain in vivo. The study of the in vitro sensitivity of HBV polymerase mutants to nucleoside analogs will be important to design new anti-HBV strategies.

Analysis of a hepatitis delta virus isolate from the Central African Republic

Based on the analysis of HDV genomes from different areas of the world, three genotypes of HDV have been identified. Genotype I is the most prevalent and widespread. Genotype II is represented by two isolates from Japan and Taiwan. Genotype III has been found only in the Amazonian basin where it is associated with a history of severe disease, fulminant hepatitis with microvesicular steatosis (spongiocytosis). We report here the cloning and the analysis of the complete viral genome from woodchuck serum-derived HDV RNA after transmission from Central African Republic (RCA) patients with fulminant spongiocytic delta hepatitis. Two overlapping cDNA fragments, covering the entire HDV genome, were generated by RT-PCR and cloned. Three clones obtained from each fragment were fully sequenced. A complete consensus RCA HDV genome was reconstituted. The individual and the consensus nucleotide sequences were compared with those of 16 other fully sequenced isolates belonging to the three genotypes. Phylogenetic trees generated by the neighbour joining method firmly place our isolate in genotype I, and show that this RCA isolate differs significantly from the east African isolates previously analysed. Transfection experiments showed that the isolate is replication-competent, but less so than the control "wild-type" strain. Two novel mutations encountered in this work, one in the antigenomic ribozyme sequence and one affecting delta antigen, were studied.

Inhibitory effect of 2'-fluoro-5-methyl-beta-L-arabinofuranosyl-uracil on duck hepatitis B virus replication

The antiviral activity of 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil (L-FMAU), a novel L-nucleoside analog of thymidine known to be an inhibitor of hepatitis B virus (HBV) replication in hepatoma cells (2.2.1.5 cell line), was evaluated in the duck HBV (DHBV) model. Short-term oral administration (5 days) of L-FMAU (40 mg/kg of body weight/day) to experimentally infected ducklings induced a significant decrease in the level of viremia. This antiviral effect was sustained in animals when therapy was prolonged for 8 days. The histological study showed no evidence of liver toxicity in the L-FMAU-treated group. By contrast, microvesicular steatosis was found in the livers of dideoxycytidine-treated animals. L-FMAU administration in primary duck hepatocyte cultures infected with DHBV induced a dose-dependent inhibition of both virion release in culture supernatants and intracellular viral DNA synthesis, without clearance of viral covalently closed circular DNA. By using a cell-free system for the expression of an enzymatically active DHBV reverse transcriptase, it was shown that L-FMAU triphosphate exhibits an inhibitory effect on the incorporation of dAMP in the viral DNA primer. Thus, our data demonstrate that L-FMAU inhibits DHBV replication in vitro and in vivo. Long-term administration of L-FMAU for the eradication of viral infection in animal models of HBV infection should be evaluated.

A novel vector for the study of hepatitis delta virus replication

In order to study HDV replication without the difficulties caused by the use of a multimeric construction and to obtain a selectable expression vector, a minimal amount of antigenomic HDV cDNA, sufficient to initiate RNA dependent replication was cloned into the plasmid pUTSV1. The first plasmid, pUTdelta1.7, contained 1.7 genomes of HDV cDNA. After transfection of pUTdelta1.7 into HuH7 cells, antigenomic HDV RNA was produced, processed and could enter into the replicative cycle of HDV. However, after transfection of an antigenomic ribozyme mutant (pUTdelta1.7(AGR)) constructed on the same model, plasmid DNA dependent production of genomic HDV RNA was observed, especially in COS7 cells. It seems that a promoter within vector sequences downstream from the HDV insert may initiate counter-clockwise transcription of the plasmid. The presence of two genomic ribozymes in the insert permits the excision of a genome length genomic HDV RNA from this counter-clockwise transcript. In order to allow quantitative analysis of HDV replication, this problem was eliminated by removing the second genomic ribozyme from the insert to give the vector pUTdelta1.5. This vector can be used conveniently for transfection experiments to explore HDV biology.

Heterogeneity of hepatitis B virus (HBV) core gene in a patient with HBV-associated cirrhosis and serum negativity for anti-HBc

AIMS

We describe here the case of a patient suffering from severe chronic hepatitis B associated with an unusual hepatitis B virus serology: HBsAg and HBeAg were both positive while anti-HBc was negative by radioimmunoassay.

METHODS

A very sensitive anti-HBc ELISA (IMx CORE) was performed and was able to detect anti-HBc sporadically throughout the clinical course. Molecular characterization of hepatitis B virus strains in this patient enabled us to explain this particular serological and clinical pattern of hepatitis B virus infection.

RESULTS

Hepatitis B virus genotype determined by size polymorphism of the core gene and the pre-S region was found to be D/E and consistent with the results of serological subtyping (HBV ayw2-4). DNA sequence analysis of the pre-C/C region showed the presence of significant nucleotide changes. In association with a wild type hepatitis B virus strain, we could detect at least four hepatitis B virus variants with nucleotide deletions leading to a frameshift in the core gene. According to the position of the mutations, these hepatitis B virus core variants are expected to be defective for B-cell epitopes and TH-cell epitopes.

CONCLUSIONS

These mutations explain the low level production of anti-HBc antibody. It is noteworthy that the absence of detectable anti-HBc in serum was associated with severe liver damage, suggesting that the deficient humoral response to HBcAg was not accompanied by a cellular immune tolerance to HBc/eAg, the supposed target for cytotoxic T-cell lysis.

[Treatment of hepatitis C]

The treatment of hepatitis C virus (HCV) infections is essentially known for chronic hepatitis C and is mainly restricted to interferon alpha. Initial trials have indicated that around 50% of the patients with chronic hepatitis C respond to alpha interferon (administered at 3 MU, thrice weekly, during 6 months) by normalizing alanine aminotransferase at the end of therapy, although 25% were found to relapse after therapy. Normalization of biochemical tests is associated with an improvement in liver histological features and with decrease or loss of HCV from serum and liver. Response to therapy is influenced by both duration and dose levels of the treatment. Following studies which showed that higher doses and longer duration were more effective than the current recommendations of 3MU thrice weekly for 6 months have recently conducted to the recent recommendation of a 12 month course of therapy using 3 MU. The outcome of therapy was also shown to be negatively influenced by longer duration of disease and presence of cirrhosis. More recently, the critical role of virological markers has been emphasized with a lower rate of response in patients infected with the genotype 1 b and a high viral load. However, these factors do not certainly predict for an individual patient the quality of the response. Therapeutical goals are: to precisely define pre-treatment scores of response able to give each individual patient the optimal treatment regimen, non responders to interferon alpha and patients with a transient benefit of therapy. Thus, development of new treatments appears critical among which those with other interferons and above all the bitherapy using ribavirin and interferon alpha which may have a marked increase in efficacy in comparison with interferon alpha used as monotherapy.

Hepatitis B, C, and D virus infections in patients with chronic hepatitis, cirrhosis, and hepatocellular carcinoma: a comparative study in Niger

Eighty-nine Sahelian African patients with chronic active hepatitis (CAH) (14), cirrhosis (49), hepatocellular carcinoma (HCC) (26), and 47 controls were tested for hepatitis B virus (HBV, hepatitis B surface antigen [HBsAg]) and hepatitis D virus (HDV, anti-HDV antibody). Seventy-three percent of the patients were positive for HBsAg versus 29.8% of the controls (P < 0.0001). With anti-HDV test, 55.0% of the patients were positive versus 17.0% of the controls (P < 0.0001). To assess the prevalence of antibody to hepatitis C virus (HCV), we used an enzyme-linked immunosorbent assay for screening (anti-HCV2): 19.1% of the patients were positive versus 6.4% of the controls (P < 0.05). An association between HBsAg and anti-HDV-positive test results was found in 46.1% of the patients versus 6.4% of the controls (P < 0.0001). A combination of HBsAg and anti-HCV2-positive test results was found in 13.5% of the patients versus 2.2% of the controls (P < 0.05). Anti-HDV and anti-HCV2 test results were positive in 13.5% of the patients versus 2.2% of the controls (P < 0.05). Triple-positive test results (HBsAg, anti-HDV, and anti-HCV2) were found in 11.2% of the patients but in none of the controls (P < 0.025). Triple-negative test results were found in 14.6% of the patients versus 57.4% of the controls (P < 0.0001). The predominant association of the chronic HBV infection with CAH, cirrhosis, and HCC is confirmed in Sahelian Africa. The HDV superinfection (chronic HBV plus HDV infections) may be a major etiology.(ABSTRACT TRUNCATED AT 250 WORDS)

Serial transmission of spongiocytic hepatitis to woodchucks (possible association with a specific delta strain)

BACKGROUND/AIMS

Outbreaks of severe hepatitis have been reported from Africa and South America. Description of the cases has shown the histological hallmark to be the presence of ballooning hepatocytes with fat drops surrounding the nucleus (spongiocytes or morula cells).

METHODS

Experimental reproduction of this syndrome for the verification of a possible role of a specific HDV strain was performed by the inoculation of serum and liver extracts from African patients (Bangui-Central African Republic), who died with this syndrome, into American woodchuck carriers of WHV (WC 231,144), the results of which were then compared with animals inoculated with a reference wild HDV strain (WC 300,173,154), and those which received material from a European fulminant HDV case (WC 88,93).

RESULTS

Following the initial inoculation, the animals receiving African inocula had a delayed anti-HDV seroconversion, high mortality and showed the presence of spongiocytes, while the other animals had a classical evolution of HDV superinfection in woodchucks. Furthermore, the African inocula caused less inhibition of WHV replication, as well as a predominant cytoplasmic expression of HDAg, in contrast to the animals which received the other inocula. The second passage experiments gave similar results.

CONCLUSIONS

We conclude that this peculiar form of HDV fulminant hepatitis can be experimentally reproduced and might be specifically related to a more pathogenic strain.

Interferon therapy for hepatitis C

Initial trials indicated that around 50% of patients respond to recombinant alpha interferon by normalizing alanine aminotransferase (ALT) at the end of therapy and that half of these relapsed within 6 months following cessation of treatment. Both dose and duration of treatment are critical in the response to therapy. Higher doses and longer duration have been suggested to be more effective than the current recommendations of 3 MUI thrice weekly for 6 months based on results of these initial studies which used ALT and histological scores to evaluate the efficacy of interferon therapy. Following studies using virological markers have shown that improvements in clinical features of disease are associated with decrease or loss of hepatitis C virus (HCV) from serum and liver. The heterogeneity of the response rates between clinical centers using identical protocol emphasizes that the selection of the patients treated was as important for the outcome that the therapy regimen itself with better responses in cases without cirrhosis and with low levels of HCV RNA. Furthermore, the genotype of HCV seems to be also critical for the response rate. Virological evaluations appears therefore crucial to assess not only HCV infection but also for the indication and monitoring of therapy.

Direct cloning and expression of PCR amplified DNA and RNA sequences: application to the hepadnaviruses nucleocapsid proteins

Gene amplification may benefit from the construction of primers that augments the speed at which cloning and protein expression proceeds. Such primers include EcoRI or HindIII linkers as well as an in phase initiation or termination codon. PCR was carried out directly from viral particles of human hepatitis B virus (HBV) and woodchuck hepatitis virus (WHV) without DNA purification and from RNA extracted from WHV infected liver. Amplified products were directly cloned in the pKK223-3 expression vector under the control of the tac promoter. The characterization of the recombinant clones expressing the nucleocapsid protein (C protein) was done by direct incubation of the filter with 125I-labelled anti-HBc and confirmed by radioimmunoassay and Western-blot analysis. This procedure allows easy selection of recombinant clones expressing a given protein and could be applied to many other genes.

Diagnostic markers of viral hepatitis B and C

Hepatitis B virus (HBV) serology has become extremely refined. As well as the recognised hepatitis B surface (HBs), hepatitis B core (HBc), and hepatitis B e (HBe) antigen-antibody systems, new markers have been introduced including pre-S1, pre-S2 for the envelope and the functional X protein. New automates have been introduced allowing flexibility in the different tests according to precise needs. The monitoring of pre-S1 antigen provides a relevant correlate of viral replication. The quantitative determination of HBV-DNA, pre-S1 Ag, and IgM anti-HBc seem most useful for the decision to use, and the monitoring of, antiviral treatment. Second generation ELISAs detect antibodies to three sets of hepatitis C virus (HCV) protein including the c22 core, and c33, and c100, which correspond to the non-structural regions (NS3 and NS4, respectively). Second generation ELISAs require confirmation by supplement assays, but their biggest limitation is the delayed appearance of anti-HCV after primary infection. In addition 10% of chronic infections with liver disease still remain seronegative despite circulating HCV RNA in serum or liver, or both. Much progress still has to be made before HCV serology can reach the level of sophistication of HBV.

New assays for quantitative determination of viral markers in management of chronic hepatitis B virus infection

We performed a quantitative study of serum hepatitis B virus (HBV) markers, including new parameters such as pre-S1 antigen (Ag), pre-S2 Ag, and anti-HBx, in 88 chronic hepatitis B surface antigen (HBsAg) carriers. New IMx assays for HBsAg and immunoglobulin M (IgM) anti-HBc detection were also used. The population studied was composed of 65 chronic hepatitis cases (40 positive for hepatitis B antigen [HBeAg] and 25 positive for anti-HBe) and 23 anti-HBe-positive, asymptomatic HBsAg carriers. Serum HBsAg levels detected by IMx were higher in HBeAg-positive than in anti-HBe-positive HBsAg carriers (all patient subgroups included) and correlated with the serum HBV DNA level (P = 0.0001). Both pre-S1 and pre-S2 Ags were detected by enzyme immunoassays in almost all HBsAg carriers. Both pre-S1 and pre-S2 Ag titers correlated positively with the serum HBsAg concentration (P = 0.0001), but only the pre-S1 Ag titer correlated with the level of serum HBV DNA (P = 0.02). The detection of low levels of IgM anti-hepatitis B core (anti-HBc) antibodies by IMx was associated with the presence of liver disease (P = 0.05) but not with the level of viral replication. The prevalence of anti-HBx antibodies detected by the enzyme immunoassay was slightly, although not significantly, higher in patients with high levels of HBV DNA (greater than 100 pg/ml) than in patients without detectable HBV DNA (P = 0.16). In anti-HBe-positive chronic HBsAg carriers, the quantitative detection of serum HBV DNA, pre-S Ag titers, and IgM anti HBc allowed us to predict which patients suffered from chronic liver disease and/or supported viral replication (P < 0.05). In a follow-up study of eight patients undergoing antiviral therapy, the clearance of both pre-S1 Ag and HBV DNA was associated with a subsequent clearance of HBV. Therefore, the quantitative determination of HBV DNA, pre-S Ags, IgM anti-HBc may prove useful for the decision to use and the monitoring of antiviral therapy, especially in anti-HBe-positive HBsAg carriers.

Transmission of serologically silent hepatitis B virus along with hepatitis C virus in two cases of posttransfusion hepatitis

The polymerase chain reaction (PCR) was used to investigate the presence of hepatitis B virus (HBV)-related DNA sequences in blood from three blood donors and two transfusion recipients who developed posttransfusion non-A, non-B hepatitis (NANBH). In the first case, the sole donor was positive for antibody to hepatitis B surface (HBs) and core (HBc) antigens and had elevated alanine aminotransferase (ALT) levels, while the recipient had no HBV serologic markers. Both the donor and the recipient had serologic markers of hepatitis C virus (HCV) and were found positive for HBV DNA and HCV RNA sequences by PCR. The second case involved two donors and one recipient. Serologic tests for conventional HBV markers were negative in all three individuals, but one of the donors had elevated ALT. HBV DNA sequences were detected by PCR in the serum of the recipient and of the donor with high ALT, but not in the serum of the donor with normal ALT. Anti-HCV was detected in the serum of the recipient and of the suspect donor but not in that of the donor with normal ALT. The sequences amplified in the S region and determined after cloning of PCR products for both donor-recipient pairs were indistinguishable from each other and identical to the sequence of the major HBV subtype of adw in the first case and ayw in the second case. Furthermore, for the second case, an identical single-point mutation was found in both the donor and the recipient. These data confirm the transmission of conserved HBV sequences together with HCV in posttransfusion NANBH.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of pre-C region mutation in woodchuck hepatitis virus from seroconverted woodchucks

Woodchuck hepatitis virus, which shares a large degree of homology with human HBV, was examined for indications of mutational variants. No alteration in the pre-C region was found, but as in HBV, viral DNA could still be detected by PCR after seroconversion to anti-WHe.

Functional epitope analysis of the human CD11a/CD18 molecule (LFA-1, lymphocyte function-associated antigen 1) involved in HIV-1-induced syncytium formation

After binding to the CD4 receptor, the human immunodeficiency virus 1 (HIV-1) may enter the T cell and induce the formation of multinucleated giant cells (syncytia). As well as the CD4 molecule, other molecules, such as the lymphocyte function-associated antigen 1 (LFA-1, CD11a/CD18) have been shown to be involved in HIV-1-mediated cell fusion. This study was designed to define regions on the human CD11a/CD18 molecule important for the HIV-1-induced syncytium formation. A CD11a/CD18 MoAb panel discriminating at least five distinct and spatially distant domains on the LFA-1 molecule was used. Comparison of the functional activity of different MoAbs demonstrated that all epitopes of the LFA-1 molecule were not of equal importance in HIV-1-induced syncytium formation between H9.III cells chronically infected with HIV-1 and uninfected CD4+ SupT1 cells. We also demonstrated that CD11a/CD18 MoAbs inhibit syncytia formation only at the level of the uninfected SupT1 cells, suggesting that the LFA-1 molecule expressed on SupT1 cells interacts with ligand(s) expressed on the infected H9.III cells. Two potential LFA-1 receptors on the H9.III cells were tested: the ICAM-1 molecule (intercellular adhesion molecule 1, CD54) and the HIV-1 transmembrane glycoprotein 41 (gp41). A CD54 MoAb (84H10) partially inhibited syncytia formation, thus demonstrating the involvement of the ICAM-1 molecule in the HIV-1-mediated cell fusion. However, the CD11a/CD18 MoAbs do not inhibit binding of the viral envelope glycoprotein gp41 to the cell surface, irrespective of the MoAb concentration used. Although we have not been successful in identifying all candidate fusion receptors for the LFA-1 molecule, these data suggest that some LFA-1 regions are important for syncytium formation and, therefore, in the cell-to-cell transmission of virus and in the spread of infection.

Detection of pre-S1 proteins in peripheral blood mononuclear cells from patients with HBV infection

The presence of pre-S1 proteins in peripheral blood mononuclear cell (PBMC) samples from 115 patients with different forms of hepatitis B virus (HBV) infection was investigated by Western blot. Among 67 chronic HBsAg carriers, HBV antigens were detected in the PBMC in 80% for HBsAg, 27% for HBc/e Ag and 34% for pre-S1 proteins. The detection of pre-S1 proteins in PBMC was significantly associated with the presence of serum markers of HBV replication (HBV DNA and/or DNA polymerase). In the group of 48 consecutive patients negative for serum HBsAg, but positive for anti-HBc with or without anti-HBs, HBsAg and pre-S1 proteins could be detected in PBMC. This finding was more frequent among anti-HIV-positive patients (77 and 23% of the cases, respectively) than in the negative ones (23 and 4% of the cases, respectively). The detection of HBV DNA and polyadenylated RNA in some of the PBMC samples positive for HBV proteins suggests that these proteins may be expressed in PBMC, especially during intense HBV replication. In patients negative for serum HBsAg, PBMC may constitute a reservoir of HBV.

Correlation between HBV DNA detection by polymerase chain reaction and Pre-S1 antigenemia in symptomatic and asymptomatic hepatitis B virus infections

The presence of hepatitis B virus (HBV) genome in sera from 73 symptomatic and asymptomatic HBsAg carriers was studied by the polymerase chain reaction (PCR) with primers specific for the S and C regions. Pre-S proteins of the HBV envelope were detected in serum by a specific monoclonal antibody in a double immunoradiometric assay. Out of twenty-five symptomatic patients with chronic active hepatitis (14 with HBeAg and 11 with anti-HBe), all were positive for HBV DNA by PCR, while 14/14 HBeAg and 2/11 (18%) of the anti-HBe patients were positive by dot blot hybridization. All but one anti-HBe patient (96%) carried Pre-S1 proteins. Among the asymptomatic HBsAg carriers, HBV DNA was detected by PCR in 14/14 (100%) HBeAg positive patients and in 25/34 (73%) anti-HBe positive patients. Pre-S1 proteins were found, respectively, in 14/14 (100%) and 11/22 (50%) of the same cases tested in parallel. The 20 healthy blood donors devoid of HBV markers and with normal transaminases tested were found negative for HBV DNA using PCR. Out of 12 patients who recovered from acute hepatitis B, all were found negative by PCR analysis after a mean follow up of 1 year after seroconversion to anti-HBs. When serial samples from 2 patients (one with acute hepatitis B, the other with chronic hepatitis B) were tested for the presence of HBV DNA and of Pre-S1 proteins, both markers showed parallel development.(ABSTRACT TRUNCATED AT 250 WORDS)

Early and frequent detection of HBxAg and/or anti-HBx in hepatitis B virus infection

To clarify the significance of the X gene of hepatitis B virus, we have tested for anti-HBx in the serum and HBxAg in the liver at different stages of the natural history of hepatitis B virus infection. Sera were screened by enzyme-linked immunosorbent assay and positive results confirmed by immunoblot. Purified recombinant MS2 Pol-HBx fusion protein was used as target for both assays. Among serial sera of patients with nonfulminant acute hepatitis, 24 of 64 patients (37.5%) were positive for anti-HBx. In fulminant cases, 15 of 36 patients (42%) had anti-HBx. In chronic hepatitis patients with high rates of hepatitis B virus replication, we found a significantly (p less than 0.01) higher prevalence of anti-HBx, 14 of 25 patients (56%), than in those with low replication, 14 of 66 patients (21%), or among asymptomatic HBsAg carrier blood donors (20 of 126 = 16%) without detectable hepatitis B virus replication (p less than 0.0001). The highest prevalence of anti-HBx was found in HBsAg carriers with cirrhosis (41 of 54 patients = 76%) and/or with hepatocellular carcinoma (18 of 33 patients = 54%). The findings suggest that anti-HBx appears as a common and early marker of hepatitis B virus infection, transient in self-limited hepatitis but persisting with progression to chronicity. In chronic hepatitis, the prevalence of anti-HBx correlated with the intensity and duration of hepatitis B virus replication but neither with the severity of the liver disease nor with malignant transformation per se.(ABSTRACT TRUNCATED AT 250 WORDS)

Different forms of hepatitis B virus DNA and expression of HBV antigens in peripheral blood mononuclear cells in chronic hepatitis B

The presence of both hepatitis B virus (HBV) DNA and HBV antigens (HBsAg, HBeAg) was assessed in peripheral blood mononuclear cells (PBMC) from 32 patients chronically infected with HBV. Three different molecular forms of HBV DNA were observed: free monomers (5), high-molecular-weight free concatemers (11), and integrated HBV DNA (9). The HBV DNA patterns in the PBMC were different from those found in liver and did not correlate with any specific profile of serum HBV markers. When the same PBMC were assayed for HBsAg, 22 of the 25 HBV DNA positive samples, but only three of the seven HBV DNA negative samples, were positive. By contrast, none of the PBMC samples from five healthy HBV vaccine recipients gave any positive signal in the HBV DNA or HBsAg assays. In some patients, T and B cells, monocytes, and polymorphonuclear (PMN) cells were assayed separately, showing that the DNA pattern was similar for these different leucocytes subsets and ruling out the possibility that these patterns might reflect PMN cell contamination. Thus, in chronic HBV infection, 87.5% (28/32) of patients were found to contain at least one HBV marker in their PBMC, and a strong correlation was found between the presence of HBV DNA and viral antigens, suggesting a specific expression of HBV encoded proteins.

Delta infection in chronic HBs Ag carriers in Tunisia: high prevalence in chronic asymptomatic HBs Ag carriers and in HBs Ag positive cirrhosis

The presence of hepatitis B virus DNA, delta antigen and anti-delta antibodies was examined in 159 Tunisian chronic HBs Ag carriers: 45 were asymptomatic and 114 suffered from cirrhosis. Serum hepatitis B virus DNA was detected in two (4.5%) asymptomatic HBs Ag carriers and in 11 (10%) HBs Ag positive cirrhosis patients. The prevalence of HDV infection determined by the presence of anti-delta was relatively high in asymptomatic HBs Ag carriers (33%) and in HBs Ag positive cirrhosis patients (21%). Active ongoing HDV infection, detected by serum HD Ag and anti-delta IgM, was shown in five patients with cirrhosis and active hepatitis B virus replication. We conclude that hepatitis delta virus may be endemic in Tunisia and does not always inhibit hepatitis B virus replication.

[Significance of the expression of pre-S proteins in mononuclear blood cells in chronic hepatitis caused by the hepatitis B virus]

In chronic viral type B hepatitis, the presence in the serum of pre-S proteins of hepatitis B virus (HBV) envelope reflects viral replication. As peripheral blood mononuclear cells (PBMC) are known to be target cells for HBV replication, the aim of our study was to investigate the clinical relevance of pre-S protein expression in PBMC. Fifty-seven patients with chronic type B hepatitis and HBs antigenemia were studied. Following separation using the Ficoll gradient, the PBMC were lysed and studied for pre-S proteins by Western blot. HBs Ag and HBc/e Ag were assayed in parallel by radioimmunoassay. HBs Ag was detected in PBMC in 86 percent of cases, HBc/e Ag in 28 percent of cases and pre-S proteins in 34 percent of cases. A statistically significant association was found between the presence of HBc/e Ag in PBMC and both the serum HBe Ag (chi 2 test, p less than 0.01) and the serum viral DNA/DNA polymerase (t test, p = 2.10(-4)). The pre-S protein expression in PBMC was significantly associated with higher levels of DNA/DNA polymerase activity (chi 2 test, p less than 0.05). The expression of pre-S proteins in PBMC appears therefore to correlate with the HBV viral replication phase. The HBc/e Ag and pre-S protein detection in PBMC therefore offers a reliable non invasive approach to tissular viral replication. The clinical relevance of pre-S testing in PBMC was illustrated by the study of 12 cases of chronic active hepatitis positive for anti-HBe but with no or low level of serum DNA polymerase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

[Prevalence of viral hepatitis B markers in the region of Tataouine (southern Tunisia)]

Tataouine (South Tunisia) has been subject to several viral hepatitis epidemics during these last years. Prospective study has been conducted to define the prevalence of HVB infection. It has examined 511 cases, the age of whom was between 1 month and 70 years, reported in groups through the OMS recommendations, taking into account the number of inhabitants in each area. The global prevalence was 6.2% for HBs Ag and 18.5% for HBs antibody. These results were not different from the frequencies observed within the Tunisian population in general. The analysis of this study according to these groups, shows that in three areas (Ras El Oued, Bir 30, Dhibet) 60 to 80% of cases have at least one of HVB marquers, whereas the prevalence in other areas (Rogba) was very weak. The geographic repartition of HVB infection corresponds approximatively to areas that have been the most infected by the last hepatitis epidemics. A second study has completed and confirmed the results of the first one, taking into consideration a more important number of cases from areas of strong and weak endemicity. 596 sera have been examined in Rogba which counts 2000 inhabitants and is a weak endemicity area. 528 sera have been examined in the three areas of strong endemicity: 199 in Bir 30, 201 in Dhibet and 128 in Ras El Oued, which count around 2000 inhabitants, too. The percentage of cases presenting at least one of HVB serological marquers reaches 84 in Dhibet, 70 in Ras El Oued, 50 in Bir 30 and 24 in Rogba. This HBs Ag frequency is 3.8% in Rogba, 15% in Bir 30, 24% in Ras El Oued and 26.3% in Dhibet. It seems that the HVB is the virus of hepatitis epidemics observed in Tataouine at least in the three strong endemicity areas.

Anti-HBc screening for the prevention of perinatal transmission of hepatitis B virus in France

As anti-HBc screening has been proposed for blood donor testing, we investigated its effectiveness during pregnancy. Among 4,023 successive pregnant women screened for anti-HBc, 539 (13.4%) were positive and further tested for HBsAg and anti-HBs. HBsAg was found in 73 (1.81%) and anti-HBc only was positive in 66 (1.64%). Among the 73 women positive for HBsAg, HBV DNA was found in the serum of seven, the cord blood of two, the placenta of three. Of the 58 infants given HBV immunoglobulins and vaccine, only four had transient HBsAg. None of the 66 women positive for anti-HBc only had anti-HBc IgM, HBeAg, or HBV DNA in serum, cord blood or placenta but five women became HBsAg positive before, at, or after delivery. Among the infants born of these 66 mothers, three had high ALT, two had HBsAg and one HBV DNA without HBsAg. Screening for anti-HBc may be cost effective, at least in low HBV prevalence areas, since there is evidence for infectivity of pregnant women positive for anti-HBc only.

High affinity human monoclonal antibodies directed against hepatitis B surface antigen

Peripheral blood mononuclear cells from donors immunized with hepatitis B vaccine (Pasteur Hevac B) were transformed with Epstein-Barr virus. Two polyclonal cell lines, producing antibodies to hepatitis B surface antigen were established and cloned. Seven clones were isolated; they secreted between 10 and 20 micrograms/ml of HBs specific IgG1 kappa or lambda antibody with anti-HBs titer of 300-800 IU/ml. These human antibodies expressed the anti 'a' specificities and had high affinity and avidity; their potential use as reagents for hepatitis B virus detection and for passive immunotherapy is under study.

Prevalence and significance of hepatitis B virus antigens: expression in peripheral blood mononuclear cells in chronic active hepatitis

One-hundred four chronic active hepatitis (CAH) patients were investigated for the expression of the hepatitis B virus (HBV) surface and core gene products (HBs Ag, HBc/HBe Ags) in peripheral blood mononuclear cells (PBMC). Two-thirds of 59 HBs antigenemic patients expressed HBs Ag in PBMC but 26% of cases positive for both anti-HBs and anti-HBc also expressed HBs Ag while none of the controls reacted. Among HBs antigenemic patients, only those who replicated HBV express the core gene products (HBc and/or HBe Ag) in PBMC, and high replicators did so more often than low replicators (P less than 0.05). The HBs Ag prevalence in PBMC, although slightly higher among HBe Ag/DNAp-positive cases could not be correlated with the intensity of HBV replication. In 16 cases (8 replicants and 8 nonreplicants) HBV DNA was detected by DNA hybridization spot test, while 8 controls devoid of HBV markers were negative. Both T and non-T cells reacted similarly for antigenic or genomic HBV markers. When the expression of HBV gene products in PBMC among 43 cases with HBs antigenemia was compared with that in the liver, a good correlation was found in 70% of cases for HBs Ag but in only 40% for HBc and HBe Ags. By contrast, among 38 cases lacking HBs Ag in the serum but positive for anti-HBc with or without anti-HBs, concordance between liver and PBMC expression of core gene products (69%) was better than for HBs antigenemic patients (40%). These data suggest that PBMC including T lymphocytes may represent the second-best HBV target and may mimic the steps of HBV cycle within hepatocytes.

Evidence for the presence of duck hepatitis B virus in wild migrating ducks

A virus closely related to duck hepatitis B virus (DHBV) was isolated from serum and liver samples of wild migratory ducks (mallards) caught in two separate wildlife reserve parks in France. In the first one (Dombes region) 12% of wild mallards were positive for DHBV, and in the second (River Somme) 3% of mallards were found positive. The DHBV isolated from the serum of wild mallards was also associated with an endogenous DNA polymerase activity capable in vitro of completing a partially double-stranded viral DNA into a fully double-stranded DNA of 3 kb. The various replicative DNA forms reported for DHBV were also detected in the liver of wild viraemic mallards. The DNA restriction enzyme pattern of the wild mallard strain differed from that of American and French strains of DHBV. The wild mallard strain DHBV was experimentally transmitted to mallard and Pekin ducklings and induced a chronic viraemia in both varieties of infected birds. This strain might be the common ancestor of all DHBV strains isolated from domestic ducks world-wide. The discovery of a DHBV-related virus in the natural wild population might be an important clue in the study of the different roles of environmental, host and viral factors in the pathogenesis of DHBV infection, and their possible oncogenic action in ducks.

Woodchuck hepatitis virus infection: serologic and histopathologic course and outcome

Five out of seven American woodchucks inoculated with woodchuck hepatitis virus developed antigenemia after 2 to 13 weeks followed by an antibody response. One animal became a carrier, and another animal exhibited a primary antibody response. Clinical disease was not obvious and aminotransferase elevation could not be demonstrated. Liver biopsy showed mononuclear portal infiltration and little parenchymal cell necrosis.

Immunopathologic aspects of woodchuck hepatitis

The natural history of infection with woodchuck hepatitis virus (WHV) has been studied in a colony of 38 Marmota monax. Besides serologic assessment for WHV markers, light-microscopic findings of 61 liver biopsies were correlated with the results of immunofluorescence analysis for nucleocapsid (WHcAg) and surface (WHsAg) antigens. Twenty-four chronic WHsAg carriers all featured signs of continuous viral replication. Two major immunomorphologic patterns were observed in their livers: 1) portal hepatitis in which WHcAg accumulated in the cytoplasm and WHsAg was associated with the hepatocyte membrane and 2) periportal hepatitis in which WHcAg shifted toward nuclear localization and WHsAg became mostly intracytoplasmic. Progression from portal to periportal hepatitis, observed in 7 woodchucks, appeared to be induced by a partial recovery of specific immune reactivity to WHV, insufficient, however, to interrupt WHV replication. Deposits of WHsAg and immunoglobulins were present in the kidney and spleen of animals with severe hepatitis.

Comparison of properties of woodchuck hepatitis virus and human hepatitis B virus endogenous DNA polymerases

The principal properties of the DNA polymerases of woodchuck hepatitis virus and human hepatitis B virus were compared. The enzymes of both viruses exhibited optimal activities in the same range of pH, ionic strength, and MgCl2 concentration. Like human hepatitis B virus DNA polymerase, the woodchuck hepatitis virus DNA polymerase was strongly inhibited by phosphonoformic acid but not by phosphonoacetic acid and aphidicolin. Similar inhibition patterns for both enzymes were observed with arabinofuranosyl nucleotides (9-beta-D-arabinofuranosyladenine-5'-triphosphate, 1-beta-D-arabinofuranosylcytosine-5'-triphosphate, 1-beta-D-arabinofuranosylthymine-5'-triphosphate) and dideoxythymidine triphosphate, whereas no effect was obtained with corresponding nucleosides. The therapeutic significance of these results and the relevance of the woodchuck as an experimental animal model for the study of human hepatitis B virus infections are discussed.

[Spontaneous and experimental infection of alpine marmots (Marmota marmota) by the North American woodchuck hepatitis virus (Marmota monax). Initial results]

Summer's discovery in 1978 of a DNA virus, very close to human Hepatitis B virus in a woodchuck population in the U.S.A. (Pennsylvania) was a confirmation of the first description made by Snyder at Penrose Research Laboratory (Philadelphia). It was the first animal model of human B hepatitis infection. The comparative study of morphological, ecological and ethological characteristics of the marmot (Marmota marmota) and the woodchuck (Marmota monax) enables an easy distinction between these two species. The natural infection of M. monax by the WHV shows that the woodchuck is a good model for human B hepatitis and should be extended to M. marmota. A sample of 24 marmots caught in the Alpes of Haute-Provence has not revealed any spontaneous infection in these animals by the woodchuck virus. The failure of experimental inoculation of the marmot (24 animals) with the WHV confirms the refractory status of this species (no viremia and very low and short serological response with or without an immunosuppressive treatment). These preliminary results require a confirmation in other animals of different age and geographical region and also by using more specific tests such as molecular hybridization, research on DNA polymerase and direct transfection trials.

Use of the cross-reactivity with hepatitis B virus antigens and antibodies for the demonstration of a woodchuck hepatitis virus 'e' antigen-antibody system

Woodchucks hepatitis virus (WHV)-associated antigens and antibodies were studied using current sensitive radio- or enzyme immunoassays (RIA, EIA). A significant cross-reactivity was observed between hepatitis B surface antigen (HBsAg) and woodchuck hepatitis surface antigen (WHsAg) using RIA or EIA (Abbott Laboratories, North Chicago, Ill., U.S.A.) although not with two other commercial EIA tested (Organon Technika, Oss, The Netherlands; Behringwerke AG, Marburg, F.R.G.). A weak but significant reactivity was also found when woodchuck sera positive for WHsAg or anti-WHs by immunodiffusion were tested for HBeAg and anti-HBe by RIA, suggesting the existence of a WHeAg-anti-WHe system in infected woodchucks. The specificity of this e-anti-e reactivity in the woodchuck was further confirmed by successful absorption experiments. WHsAg and WHeAg could be distinguished serologically by immunodiffusion and separated from each other by ultracentrifugation and ammonium sulphate precipitation. A WHeAg preparation was used to boost the presumed natural antibody activity of an immune woodchuck. The specific anti-HBe response detected by RIA during the immunization experiments demonstrated the existence of a soluble WHeAg cross-reacting with the human HBe-anti-HBe system. This was confirmed in immunodiffusion by a partial identity between the precipitin lines formed by the WHeAg-anti-Whe and HBeAg-anti-HBe reaction. Whether the WHe-Ag-anti-WHe system wil mimick HBeAg and anti-HBe in all their clinico-pathological correlations, deserves further study.

Identification and detection of long incubation non-A, non-B hepatitis virus and associated antigens or antibodies

Three distinct antigen/antibody systems supposedly associated with an HBV-like virus of non-A, non-B hepatitis have been identified. Because of previously demonstrated cross-reactivity with HBe/3 and HBc antigens and other analogies the following terminology is tentatively used. 1. The previously reported serum antigen has been redesignated non-A, non-B e antigen, since it is equivalent to HBe/3 Ag and cross-reacts with it. Non-A, non-BeAg or Ab were detected in 51/62 post-transfusion and 11/56 sporadic acute non-A, non-B hepatitis cases, and in 12/14 cases affecting staff members. In non-A, non-B chronic persistent or active hepatitis and cryptogenic cirrhosis, the prevalence was similarly high: 14/18, 22/48 and 12/18 respectively. Ten out of 26 implicated blood donors were found positive for non-A, non-BeAg accounting for 7 out of 8 post-transfusion cases. A high prevalence of non-A, non-BeAg was also found in haemophiliacs (11/48) and haemodialysed patients (6/42), whereas anti-non-A, non-Be was respectively detected in 4/48 and 6/42 of these cases. 2. Using immunofluorescence, a second antigen termed non-A, non-BcAg has been identified in liver biopsies from 55/84 non-A, non-B chronic hepatitis or cryptogenic cirrhosis cases. All 8 positive biopsies examined by electron microscopy revealed clusters of 22--25 nm intranuclear particles identical to those described in chimpanzees. Anti-non-A, non-Bc detectable by counter-electrophoresis and indirect immunofluorescence was found in the serum of all patients of which biopsy was positive for non-A, non-BcAg. Anti-non-A, non-Bc was also detected in 5/5 non-A, non-BeAg positive cases of post-transfusion hepatitis, 2--6 weeks after onset end remained positive for the 6 month follow-up period. 3. A third antigen, tentatively designated non-A, non-BsAg, has been found less frequently than non-A, non-BeAg in serum. However, it was detectable in 3/18 and 2/12 washed ultracentrifugation pellets of sera positive for non-A, non-BeAg or anti-non-A, non-Be, respectively.

[Identification of a virus similar to hepatitis B virus in non-A non-B hepatitis]

Hepatitis B virus-like particles (including DANE particles) with DNA polymerase activity but negative for HBs Ag have been identified in NON-A, NON-B hepatitis sera positive for HC Ag. Although specifically associated with the particles, HC Ag is not a surface antigen of the hepatitis C virus identified here for the first time. The relationship of this agent with HBV seems obvious, and deserves further study.