Use of serum biomarkers in staging of canine hepatic fibrosis.

Accurate staging of hepatic fibrosis (HF) is important for treatment and prognosis of canine chronic hepatitis. HF scores are used in human medicine to indirectly stage and monitor HF, decreasing the need for liver biopsy. We developed a canine HF score to screen for moderate or greater HF. We included 96 dogs in our study, including 5 healthy dogs. A liver biopsy for histologic examination and a biochemistry profile were performed on all dogs. The dogs were randomly split into a training set of 58 dogs and a validation set of 38 dogs. A HF score that included alanine aminotransferase, alkaline phosphatase, total bilirubin, potassium, and gamma-glutamyl transferase was developed in the training set. Model performance was confirmed using the internal validation set, and was similar to the performance in the training set. The overall sensitivity and specificity for the study group were 80% and 70% respectively, with an area under the curve of 0.80 (0.71-0.90). This HF score could be used for indirect diagnosis of canine HF when biochemistry panels are performed on the Konelab 30i (Thermo Scientific), using reagents as in our study. External validation is required to determine if the score is sufficiently robust to utilize biochemical results measured in other laboratories with different instruments and methodologies.

Mutations in TP53 and CTNNB1 in Relation to Hepatitis B and C Infections in Hepatocellular Carcinomas from Thailand.

Hepatocellular carcinoma (HCC) may develop according to two major pathways, one involving HBV infection and TP53 mutation and the other characterized by HCV infection and CTNNB1 mutation. We have investigated HBV/HCV infections and TP53/CTNNB1 mutations in 26 HCC patients from Thailand. HBV DNA (genotype B or C) was detected in 19 (73%) of the cases, including 5 occult infections and 3 coinfections with HCV. TP53 and CTNNB1 mutations were not mutually exclusive, and most of TP53 mutations were R249S, suggesting a significant impact of aflatoxin-induced mutagenesis in HCC development.

Impact of patatin-like phospholipase-3 (rs738409 C>G) polymorphism on fibrosis progression and steatosis in chronic hepatitis C.

UNLABELLED: Only 20% of patients with chronic hepatitis C (CHC) will develop cirrhosis, and fibrosis progression remains highly unpredictable. A recent genome-wide association study identified a genetic variant in the patatin-like phospholipase-3 (PNPLA3) gene (rs738409 C>G) associated with steatosis that was further demonstrated to influence severity of fibrosis in nonalcoholic fatty liver disease. The aim of this study was to assess the impact of this polymorphism on histological liver damage and response to antiviral therapy in CHC. We recruited 537 Caucasian CHC patients from three European centers (Brussels, Belgium [n = 229]; Hannover, Germany [n = 171]; Lyon, France [n = 137]); these patients were centrally genotyped for the PNPLA3 (rs738409 C>G) polymorphism. We studied the influence of rs738409 and other variants in the PNPLA3 region on steatosis and fibrosis assessed both in a cross-sectional and longitudinal manner. Seven other variants previously associated with fibrosis progression were included. Finally, we explored the impact of rs738409 on response to standard antiviral therapy using the interferon lambda 3 (IL28B) [rs12979860 C>T] variant both as a comparator and as a positive control. After adjustment for age, sex, body mass index, alcohol consumption, and diabetes, rs738409 mutant G allele homozygote carriers remained at higher risk for steatosis (odds ratio [OR] 2.55, 95% confidence interval [CI] 1.08-6.03, P = 0.034), fibrosis (OR 3.13, 95% CI 1.50-6.51, P = 0.002), and fibrosis progression (OR 2.64, 95% CI 1.22-5.67, P = 0.013). Conversely, rs738409 was not independently associated with treatment failure (OR 1.07, 95% CI 0.46-2.49, P = 0.875) and did not influence clinical or biological variables. CONCLUSION: The PNPLA3 (rs738409 C>G) polymorphism favors steatosis and fibrosis progression in CHC. This polymorphism may represent a valuable genetic predictor and a potential therapeutic target in CHC liver damage.

The role of nucleoside and nucleotide analogues in nodular regenerative hyperplasia in HIV-infected patients: a case control study.

BACKGROUND & AIMS: Nodular regenerative hyperplasia (NRH) leading to non-cirrhotic portal hypertension has been described in HIV-infected patients and has been linked to didanosine. The relation between NRH and other antiretrovirals remains unclear. METHODS: A case-control study was performed in 13 patients with NRH and 78 controls matched for time of inclusion, baseline CD4, and duration of follow-up. Univariate and multivariate conditional logistic regression analyses were performed. RESULTS: Control patients and patients with NRH were similar at baseline regarding demographics and biological data with the exception of older age for patients with NRH (43.9 vs. 33.5 years, p=0.044). At the time of NRH diagnosis, cases had a lower CD4 count (327 vs. 468/mm(3), p=0.013), a similar CD4 percentage (24 vs. 26.2%, p=0.7), a lower platelet count (169 vs. 228 giga/L, p=0.003) and a higher AST level (33 vs. 26 IU/L, p=0.001) than controls. Univariate analysis demonstrated that patients with NRH had been exposed longer than controls to didanosine, stavudine, tenofovir, didanosine+stavudine, and didanosine+tenofovir. The age at baseline [OR 2.2 (1.0-5.0) per 10 years, p=0.053] and didanosine+stavudine cumulative exposure [OR 3.7 (1.4-10.2) per year, p=0.011] were independently associated with NRH. The age at baseline [OR 2.3 (1.0-5.3) per 10 years, p=0.045], cumulative exposure to didanosine [OR 1.4 (1.1-1.9) per year, p=0.023] and to tenofovir [OR 1.7 (1.0-2.8) per year, p=0.04] were independently associated with NRH when didanosine+stavudine exposure was excluded from the model. CONCLUSIONS: NRH in HIV-infected patients seems strongly related to age and the cumulative exposure to didanosine+stavudine, didanosine, and stavudine.

Pharmacological inhibition of Frizzled-7 displays anti-tumor properties in hepatocellular carcinoma.

BACKGROUND & AIMS: We previously reported the frequent overexpression of the FZD7 membrane receptor in hepatocellular carcinoma (HCC) and its role for controlling cancer phenotype. Herein, this study aimed at assessing the anticancer properties of compounds inhibiting FZD7 activity by disrupting its binding with the cytosolic Dishevelled (DVL) adaptator. METHODS: We have designed small interfering peptides (RHPDs) that are able to enter within cells and to competitively antagonize the binding of FZD7 to the PDZ domain of DVL. Their anti-neoplastic properties were assessed in vitro on a panel of human HCC cell lines and in vivo on the SV40-TAg transgenic mouse model of HCC. RESULTS: We have shown that RHPDs decrease cell viability via apoptosis depending on their affinity for PDZ, with a therapeutic index between cancerous and non-cancerous cells. RHPD properties were linked to ß-catenin degradation and PKCδ activation. In transgenic mice, intra-tumor injection of RHPDs inhibited HCC progression. CONCLUSIONS: We have completed a proof-of-concept showing that in vitro and in vivo the pharmacological inhibition of FZD7 displays anti-cancerous properties against HCC. The mechanisms can involve ß-catenin and PKCδ modulations. Further studies are warranted to design protocols showing the compatibility with systemic in vivo applications.

Non-invasive assessment of liver fibrosis progression in hepatitis C patients retreated for 96 weeks with antiviral therapy: a randomized study.

BACKGROUND: The efficacy of a maintenance therapy in non-responder patients with chronic hepatitis C has been essentially evaluated by histological semiquantitative scores. AIM: The aim was to evaluate the efficiency of 2 years of treatment with peginterferon alpha-2a vs alpha-tocopherol in these patients by histology, morphometry and blood markers of fibrosis. METHOD: Hundred and five HCV patients with a Metavir fibrosis score > or = 2 were randomized to receive peginterferon alpha-2a 180 microg/week (PEG) (n=55) or alpha-tocopherol (TOCO) 1000 mg/day (n=50) for 96 weeks. The primary endpoint was improvement or stabilization of the Metavir fibrosis score by biopsy performed at week 96. Secondary endpoints included a quantitative assessment of fibrosis by morphometry and changes in blood markers of fibrosis. RESULTS: There was no difference at baseline between PEG and TOCO according to the metavir (83.3 vs 86.8%, P=0.751) stage. The median fibrosis rate, measured with morphometry was 2.72 and 2.86% at day 0, and 3.66 and 2.82% at week 96, in the PEG and TOCO groups (P=0.90) respectively. However, the percentage of patients with metavir activity grade improvement was significantly higher in the PEG group vs the TOCO group (52.8 vs 23.7%, P=0.016). Non-invasive markers analysis did not show any significant change in both groups. CONCLUSION: Long-term therapy with peginterferon alpha-2a did not reduce liver fibrosis degree assessed by morphometry and blood tests as compared with alpha-tocopherol. Blood tests could be useful to assess liver fibrosis changes in clinical trials.

Early and strong immune responses are associated with control of viral replication and recovery in lassa virus-infected cynomolgus monkeys.

Lassa virus causes a hemorrhagic fever endemic in West Africa. The pathogenesis and the immune responses associated with the disease are poorly understood, and no vaccine is available. We followed virological, pathological, and immunological markers associated with fatal and nonfatal Lassa virus infection of cynomolgus monkeys. The clinical picture was characterized by fever, weight loss, depression, and acute respiratory syndrome. Transient thrombocytopenia and lymphopenia, lymphadenopathy, splenomegaly, infiltration of mononuclear cells, and alterations of the liver, lungs, and endothelia were observed. Survivors exhibited fewer lesions and a lower viral load than nonsurvivors. Although all animals developed strong humoral responses, antibodies appeared more rapidly in survivors and were directed against GP(1), GP(2), and NP. Type I interferons were detected early after infection in survivors but only during the terminal stages in fatalities. The mRNAs for CXCL10 (IP-10) and CXCL11 (I-TAC) were abundant in peripheral blood mononuclear cells and lymph nodes from infected animals, but plasma interleukin-6 was detected only in fatalities. In survivors, high activated-monocyte counts were followed by a rise in the total number of circulating monocytes. Activated T lymphocytes circulated in survivors, whereas T-cell activation was low and delayed in fatalities. In vitro stimulation with inactivated Lassa virus induced activation of T lymphocytes from all infected monkeys, but only lymphocytes from survivors proliferated. Thus, early and strong immune responses and control of viral replication were associated with recovery, whereas fatal infection was characterized by major alterations of the blood formula and, in organs, weak immune responses and uncontrolled viral replication.

DNA vaccination in combination or not with lamivudine treatment breaks humoral immune tolerance and enhances cccDNA clearance in the duck model of chronic hepatitis B virus infection.

This study used a duck hepatitis B virus (DHBV) model to evaluate whether a novel DNA vaccination protocol alone or associated with antiviral (lamivudine) treatment was able to clear the intrahepatic covalently closed, circular viral DNA (cccDNA) pool responsible for persistence of infection. DHBV carriers received DNA vaccine (on weeks 6, 10, 13, 14, 28 and 35) targeting the large envelope and/or core proteins alone or combined with lamivudine treatment (on weeks 1-8) or lamivudine monotherapy. After 10 months of follow-up, a dramatic decrease in viraemia and liver DHBV cccDNA (below 0.08 cccDNA copies per cell) was observed in 9/30 ducks (30 %) receiving DNA mono- or combination therapy, compared with 0/12 (0 %) from lamivudine monotherapy or the control groups, suggesting a significant antiviral effect of DNA immunization. However, association with the drug did not significantly improve DHBV DNA vaccine efficacy (33 % cccDNA clearance for the combination vs 27 % for DNA monotherapy), probably due to the low antiviral potency of lamivudine in the duck model. Seroconversion to anti-preS was observed in 6/9 (67 %) ducks showing cccDNA clearance, compared with 1/28 (3.6 %) without clearance, suggesting a significant correlation (P<0.001) between humoral response restoration and cccDNA elimination. Importantly, an early (weeks 10-12) drop in viraemia was observed in seroconverted animals, and virus replication did not rebound following the cessation of immunotherapy, indicating a sustained effect. This study provides the first evidence that therapeutic DNA vaccination is able to enhance hepadnaviral cccDNA clearance, which is tightly associated with a break in humoral immune tolerance. These results also highlight the importance of antiviral drug potency and an effective DNA immunization protocol for the design of therapeutic vaccines against chronic hepatitis B.

Impact of highly active antiretroviral therapy (HAART) on the natural history of hepatitis B virus (HBV) and HIV coinfection: relationship between prolonged efficacy of HAART and HBV surface and early antigen seroconversion.

BACKGROUND: Coinfection with hepatitis B virus (HBV) in human immunodeficiency virus (HIV)-infected patients is common. However, little is known about the natural history of chronic hepatitis B in HIV-infected populations, especially the impact of highly active antiretroviral therapy (HAART) on the outcome of HBV early antigen (HBeAg) and HBV surface antigen (HBsAg) status. METHODS: The characteristics of 92 patients coinfected with HIV and HBV were retrospectively assessed before and after HAART and lamivudine treatment to determine the impact of treatment on chronic hepatitis B and factors associated with HBeAg and/or HBsAg seroconversion. RESULTS: During follow-up, 82 patients received antiretroviral therapy, 79 of whom received HAART. Twenty-eight of the 76 patients who were administered lamivudine therapy developed lamivudine resistance mutations. While receiving antiretroviral therapy, 10 of 59 HBeAg-positive patients developed antibody to HBeAg, 3 of 10 cleared HBsAg, and 2 of 3 developed antibody to HBsAg. Two of 23 HBeAg-negative patients cleared HBsAg and developed antibody to HBsAg. HBeAg and/or HBsAg seroconversion combined with an undetectable HBV DNA level (i.e., an HBV response) correlated with a sustained HIV response (P=.001), shorter duration of antiretroviral therapy (P=.058), and more-severe disease, as evaluated by Centers for Disease Control and Prevention staging (for stage B vs. stage A, P=.029; for stage C vs. stage A, P=.069). For patients with elevated baseline alanine aminotransferase levels, the HBV response correlated significantly with a greater increase in CD4 cell count while receiving HAART. CONCLUSIONS: In HIV-HBV-coinfected patients, HBV response correlated with a sustained HIV response to antiretroviral therapy, usually HAART including lamivudine.

Progression to cirrhosis in hepatitis C patients: an age-dependent process.

BACKGROUND: Age at infection is known to be associated with disease progression rate in hepatitis C virus (HCV) infected patients. The aim of this study was to assess when cirrhosis is expected to occur according to host and viral factors. METHODS: Fibrosis progression was studied in 247 naive HCV patients using multiple regression analysis. The expected age at cirrhosis was calculated for each patient. RESULTS: Progression rate was 0.13, 0.14, 0.27, and 0.36 U of fibrosis/year for patients with age at infection or=37 years, respectively. Age at infection above 37 years was independently associated with fast progression (rate>0.13; P=0.001). Body mass index >25 kg/m2 and alanine aminotransferase>3 x ULN are also possibly associated with faster progression. Based on progression rates, the expected age at cirrhosis is 65.4, 64.6, 64.8 and 69.4 years for age at infection or=37 years, respectively. CONCLUSION: Most HCV patients, if untreated, are expected to develop cirrhosis at about 65 years, irrespective of the age at infection. Thus, age itself seems even more important than age at infection for predicting the occurrence of liver cirrhosis. A specific active monitoring and therapeutic approach should be adopted in older patients to prevent progression to cirrhosis and its complications.

Increase of doxorubicin sensitivity by doxorubicin-loading into nanoparticles for hepatocellular carcinoma cells in vitro and in vivo.

BACKGROUND/AIMS: Hepatocellular carcinoma (HCC) is known to be chemoresistant to anticancer drugs due to the multidrug resistant (MDR) transporters expression. Here, we compared in vitro and in vivo the anti-tumor efficacy of doxorubicin-loaded polyisohexylcyanoacrylate nanoparticles (PIHCA-Dox) versus free doxorubicin (Dox). These nanoparticles are known to overcome the MDR phenotype. METHODS: We first determined in vitro the 50% inhibition concentration (IC(50)) of these drugs on different human hepatoma cell lines. Secondly, the efficacy of the drugs in vivo was determined on the X/myc transgenic murine model of HCC by histological counting of apoptotic tumorous hepatocytes and by TUNEL labeling. We characterized by semi-quantitative RT-PCR the MDR-related gene (mdr1, mdr3, mrp1) expression pattern in this model. RESULTS: In vitro, IC(50) was reduced with PIHCA-Dox versus Dox for Huh7 (1.7-fold reduction; P<0.001), HepaRG (4.5-fold reduction; P<0.01), HepG2 (1.5-fold reduction; P<0.001), and HepG2.2.15 (1.5-fold reduction; P=0.059). In vivo, HCC in transgenic mice overexpressed the mdr1 and mdr3 genes and the antitumor drugs efficacy was greatly enhanced after injection of PIHCA-Dox (9.0+/-5.0%; n=15) versus Dox (4.6+/-3.3%; n=13; P=0.01) for apoptotic bodies count. CONCLUSIONS: These promising data showing a higher anti-tumor efficacy on HCC of PIHCA-Dox versus Dox, warrant further studies in both animals and humans.

Sustained HBs seroconversion during lamivudine and adefovir dipivoxil combination therapy for lamivudine failure.

We describe the case of a patient with chronic hepatitis B who became resistant to lamivudine and was treated successfully with adefovir dipivoxil in addition to lamivudine. Lamivudine resistance was associated with the selection of a L180M+M204V polymerase mutant. After the addition of adefovir dipivoxil, serum HBV DNA levels dropped by more than 4log(10), which was followed by HBsAg clearance after 22 months of combination therapy. Moreover, anti-HBs antibody titers rose above 1000 mIU/mL after 32 months of the new treatment regimen. In parallel, HBV DNA declined below 100 copies/mL by a quantitative real time PCR assay. Analysis of intrahepatic viral DNA showed a significant decline of total HBV DNA and cccDNA which was accompanied by a decrease of the number of infected cells expressing viral antigens below the detection limit of immunostaining. In parallel, liver histology analysis showed an improvement in both the activity index and fibrosis score. This report suggests that in patients who previously failed lamivudine therapy, proactive antiviral treatment may lead to a beneficial virological and clinical effect.

Histological response in patients treated by interferon plus ribavirin for hepatitis C virus-related severe fibrosis.

BACKGROUND: Studies of viral hepatitis C have suggested that fibrosis can regress, at least in patients with sustained virological response. A recent study suggested that cirrhosis was reversible in sustained and non-virological responders. AIM: To study fibrosis progression rate and cirrhosis reversion in patients treated for severe fibrosis with interferon or interferon + ribavirin. PATIENTS AND METHODS: Ninety-nine patients were treated with interferon + ribavirin and 64 with interferon. The Metavir fibrosis score and the semiquantitative fibrosis score (SFS) were used to assess fibrosis. RESULTS: In sustained responders, fibrosis progression rate decreased from 0.26 Metavir unit (interquartile range: 0.19-0.34) to -0.67 (-0.67 to 0) (P < 0.0001) and from 0.81 SFS unit (0.48-1.13) to -1.33 (-3.67 to 0) (P < 0.0001). In non-responders, fibrosis progression rate decreased from 0.25 Metavir unit (0.17-0.33) before treatment to 0 (0-0) during treatment (P = 0.002) and from 0.63 SFS unit (0.49-1.12) to 0 (-2.67-1.33) (P = 0.18). Six out of 18 (33%) sustained virological responders and four of 43 (9%) non-responders regressed from cirrhosis (F4) to severe fibrosis (F3) (P = 0.058). No patient with cirrhosis had a decrease of Metavir fibrosis score of 2 points. CONCLUSION: Interferon can slow fibrosis progression in sustained virological responders with severe fibrosis. In patients with a non-virological response and treated for 12 months the fibrosis progression rate was nil, meaning that only fibrosis stabilization could be obtained in these patients. Then, longer treatment duration (3-4 years) could be evaluated in non-virological responders.

[Autoimmunization induced by interferon alpha therapy in chronic hepatitis C]. / Auto-immunisation induite par l'interféron alpha dans un contexte d'hépatite virale C chronique.

We report the case of a 56 year-old woman with post-transfusion chronic hepatitis C who presented with a severe ALT flare up associated with a rapid progression of liver fibrosis during interferon alpha 2b therapy. Several hypotheses were considered to explain the etiology of this ALT flare: there was no viral super infection by other hepatotropic viruses, no toxic hepatitis, no metabolic disease, and no other specific liver diseases could be identified. HLA typing showed a specific profile A1 B8 DR3 (risk factor of auto-immunization during interferon alpha therapy) with antinuclear antibodies and anti smooth muscle antibodies. This case suggests that auto-immunization induced by interferon alpha should be investigated in case of ALT flare that is not followed by an HCV breakthrough.

Long-term high-dose interferon-alpha therapy delays Hepadnavirus-related hepatocarcinogenesis in X/myc transgenic mice.

The role of interferon-alpha (IFN-alpha) remains unclear in prevention of virus-induced hepatocellular carcinoma in humans. We have investigated it herewith in the X/myc transgenic mouse model of Hepadnavirus-related hepatocarcinogenesis because of upregulation of c-myc oncogene in the liver. We have demonstrated that IFN-alpha can downregulate dose-dependently hepatocyte proliferation and c-myc overexpression at early premalignant stages, while it does not affect either hepatocyte apoptosis or telomerase activity at these steps. However, continuous and long-term administration of IFN-alpha dose-dependently delays tumor onset in dysplastic livers and increases overall survival of animals, more efficiently whether started before the onset of dysplasia. The present study therefore highlights that early preventive administration of IFN-alpha can slow down evolution towards hepatocellular carcinoma via repression of c-myc and hepatocyte proliferation at premalignant steps in experimental c-myc-induced hepatocarcinogenesis. However, the transient effect observed in this study emphasizes a need to clarify the possible mechanisms of acquired resistance and subsequent therapeutic escape. Our experimental model may be a pertinent tool to explore antioncogenic properties of IFN-alpha in human cirrhotic livers showing c-myc upregulation.

[Early treatment of acute hepatitis C with interferon alpha-2b or interferon alpha-2b plus ribavirin: study of sixteen patients]. / Etude de seize cas d'hépatite C aiguë. Essai de traitement précoce par l'interféron alpha- 2b ou interféron alpha- 2b et ribavirine.

AIM OF THE STUDY: To assess the mode of transmission and the efficacy of antiviral therapy in the outcome of treated and untreated patients with acute hepatitis C. PATIENTS AND METHODS: From December 1995 to January 2001, 16 consecutive patients and their response to therapy were studied, including clinical, biochemical, virological and histological data. RESULTS: Hepatitis C virus (HCV) exposure was IVDU (38%), needle-stick injury (19%), medical procedure (6%), piercing (6%), suspected sexual contact (19%), and unknown in 2. Among 13 patients treated for acute hepatitis C, all 12 patients who completed therapy had a biochemical and virological sustained response for more than 15 months (range: 4-36 months) after stopping therapy. Therapy was tolerated in all but one patient, who stopped after 10 weeks because of side effects. Duration of treatment, type of interferon and combination with ribavirin did not modify the response to treatment. CONCLUSION: These results suggest that early intervention with interferon alpha is effective in preventing the progression of acute HCV infection to chronic hepatitis in most patients regardless of duration, type of interferon, or combination with ribavirin.

Antiviral effect of adefovir in combination with a DNA vaccine in the duck hepatitis B virus infection model.

BACKGROUND/AIMS: Combination of antiviral drugs with immunotherapeutic approaches may be a promising approach for the treatment of chronic hepatitis B. We used the duck HBV (DHBV) infection model to evaluate the efficacy of the combination of adefovir with DNA-immunization by comparison with the respective monotherapies. METHODS: Pekin ducks chronically infected with DHBV received adefovir treatment alone or in association with intramuscular immunization with a plasmid (pCI-preS/S) expressing the DHBV large envelope protein. Ducks immunized with pCI-preS/S plasmid alone and two control groups receiving empty plasmid injections or no treatment were followed in parallel. RESULTS: All animals treated with adefovir showed a marked drop in viremia titers during drug administration, followed by a rebound of viral replication after drug withdrawal. Eight weeks after the third DNA boost, the median of viremia within the duck group receiving the combination therapy tended to be lower compared to that of the other groups. In addition, our results suggest a trend to an additive effect of adefovir and DNA vaccine since a 51% decrease in DHBV DNA was observed in autopsy liver samples from combination therapy group, whereas pCI-preS/S or adefovir monotherapies decreased intrahepatic viral DNA by 38 and 14%, respectively. This effect was sustained since it was observed 12 weeks after the end of therapy. CONCLUSIONS: Our results suggest that combination of adefovir with DNA-vaccine may be able to induce a sustained antiviral effect in vivo.

Experimental transfection of Macaca sylvanus with cloned human hepatitis B virus.

Due to the absence of easily accessible animal models for the study of hepatitis B virus (HBV), the possibility of using Macaca sylvanus, a monkey originating from Morocco, North Africa, was investigated. Three monkeys were intrahepatically inoculated with a replication-competent head-to-tail HBV DNA plasmid dimer construct. The HBV surface antigen and HBV DNA were detected prior to alanine aminotransferase elevation in the serum of two of three HBV-inoculated monkeys at day 2 post-transfection and persisted for several weeks. This indicates that transfected animals developed markers of HBV infection. In addition, electron microscopy of the serum 3 weeks post-transfection showed the presence of virus particles whose shape and size were similar to complete 42 nm HBV Dane particles. Histological examination of liver tissues also revealed pathological changes not observed in uninfected controls, which strongly suggested acute hepatitis. HBV DNA was also detected by PCR in these monkey livers. Taken together, these results indicate that HBV can successfully replicate in this model and that M. sylvanus could be a potentially useful new primate model for the study of HBV replication.