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At least 289 records · Page 16Linked to original sources
PubMed2005

Replication of hepatitis B virus in primary duck hepatocytes transfected with linear viral DNA.

AIM: To explore the expression and replication of hepatitis B virus (HBV) DNA in primary duck hepatocytes (PDHs). METHODS: Complete HBV genome was transfected into PDHs by electroporation (transfected group, 1.19 x 10(12) copies of linear HBV DNA/1 x 10(7) PDHs). After 1-5 d of transfection, HBsAg and HBeAg in the supernatant and lysate of PDHs were measured with the IMX System. Meanwhile, replicative intermediates of HBV DNA were analyzed by Southern blotting and Dot blotting. PDHs electroporated were used as control group. RESULTS: HBsAg in the hepatocyte lysates of transfected group was 15.24 (1 d), 14.55 (3 d) and 5.13 (5 d; P/N values, positive > or =2.1) respectively. HBeAg was negative (<2.1). Both HBsAg and HBeAg were negative in the supernatant of transfected group. Dot blotting revealed that HBV DNA was strongly positive in the transfected group and negative in the control group. Southern blot analysis of intracellular total DNA indicated that there were relaxed circular (rc DNA), covalently closed circular (ccc DNA), and single-stranded (ss DNA) HBV DNA replicative intermediates in the transfected group, there was no integrated HBV DNA in the cellular genome. These parameters were negative in control group. CONCLUSION: Expression and replication of HBV genes can occur in hepatocytes from non-mammalian species. HBV replication has no critical species-specificity, and yet hepatic-specific regulating factors in hepatocytes may be essential for viral replication.

Animals↗
PubMed2007

Avian hepatitis B viruses: molecular and cellular biology, phylogenesis, and host tropism.

The human hepatitis B virus (HBV) and the duck hepatitis B virus (DHBV) share several fundamental features. Both viruses have a partially double-stranded DNA genome that is replicated via a RNA intermediate and the coding open reading frames (ORFs) overlap extensively. In addition, the genomic and structural organization, as well as replication and biological characteristics, are very similar in both viruses. Most of the key features of hepadnaviral infection were first discovered in the DHBV model system and subsequently confirmed for HBV. There are, however, several differences between human HBV and DHBV. This review will focus on the molecular and cellular biology, evolution, and host adaptation of the avian hepatitis B viruses with particular emphasis on DHBV as a model system.

Amino Acid Sequence↗
PubMed2005

[Inhibition of binding peptides on replication of duck hepatitis B virus].

OBJECTIVE: To study the inhibitory effect of binding peptides on duck hepatitis B virus (DHBV) replication in duck hepatocytes. METHODS: Specific binding peptides to duck hepatitis B virus polymerase (DHBVP) were screened by phage display technology (PDT), then were sequenced and synthesized. Binding peptides were added into primary culture of duck hepatocytes infected with DHBV in vitro. DHBV-DNA in the cytoplasm, cell nucleus and medium supernatant was assayed over time. RESULTS: Seven binding peptides were obtained after 3-round screening by PDT. Duck primary hepatocytes infected by DHBV were treated with above obtained binding peptides. The DHBV-DNA levels in medium supernatant and cytoplasm of duck hepatocytes treated with synthesized peptides (the 3rd and the 6th peptide) were significantly lower than those of control cells (P<0.05). CONCLUSION: Specific binding peptides to DHBVP could inhibit the replication of DHBV.

Animals↗
PubMed2005

[Combination of lamivudine with thymosin alpha1 in treatment of duck hepatitis B].

OBJECTIVE: To explore the inhibitory effect of combination of lamivudine with thymosin alpha1 (Talpha1) on the replication of duck hepatitis B virus (DHBV). METHODS: Peking ducks of 1 d old were challenged with DHBV-positive serum and used as a duck hepatitis B model. After treated with lamivudine for three months, the ducks were randomly grouped and treated with or without Talpha1 for 8 d. Serum DHBV titrate was observed by semi-quantitative PCR, and inflammation and degeneration of hepatocytes were observed by pathology examination. RESULTS: The serum DHBV titrate was significantly reduced (4483.2+/-5193.4 compared with 9351.8+/-5059.6) after lamivudine treatment, and it was reduced more significantly(1692.2+/-589.2) after combination treatment with Talpha1. Lamivudine reduced the degeneration degree of hepatocytes (3.2+/-0.8 compared with 4.6+/-0.5) and the inflammation degree of liver (6.2+/-3.3 compared with 8.6+/-2.8). The combination treatment with Talpha1 increased liver inflammation degree (9.0+/-5.2). CONCLUSION: Both Talpha1 and lamivudine may reduce the replication of DHBV in Peking ducks and combination treatment may have the better anti-virus effect and enhance immune response in liver.

Animals↗
PubMed2003

Molecular aspects of hepatitis B viral infection and the viral carcinogenesis.

Of many viral causes of human cancer, few are of greater global importance than the hepatitis B virus (HBV). Over 250 million people worldwide are persistently infected with HBV. A significant minority of these develop severe pathologic consequences, including chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). Earlier epidemiological evidence suggested a link between chronic HBV infection and HCC. Further, the existence of related animal viruses that induce acute and chronic infections of the liver, and eventually HCC, confirms the concept that HBV belongs to one of the few human oncogenic viruses. Although it is clear that chronic HBV infections are major risk factors, relatively little is understood about how the viral factors contribute to hepatocarcinogenesis. This review will introduce molecular aspects of the viral infection, and highlight recent findings on the viral contribution to hepatocarcinogenesis.

Animals↗
PubMed1991

Hepatic lesions in woodchucks (Marmota monax) seronegative for woodchuck hepatitis virus.

Livers from 128 captive woodchucks (Marmota monax) that were negative for serological markers of woodchuck hepatitis virus (WHV) were examined grossly and histologically. Livers from 19 additional seronegative woodchucks were examined only grossly. The most common finding (61% of histological specimens) was mononuclear cells in portal areas. Moderate to severe portal infiltrates in association with similar scattered mononuclear cell aggregates and extramedullary hematopoiesis, were present in woodchucks that had extrahepatic inflammatory lesions. We concluded that these changes represent a response to a variety of chronic infections and are not specific for WHV infection. Other findings included parasitic granulomas, focal and diffuse lipidosis, bile duct proliferation, lesions secondary to cardiovascular compromise, and vasculitis. Two woodchucks had neoplastic lesions.

Animals↗
PubMed1999

Cellular immune response of ducks to duck hepatitis B virus infection.

Duck hepatitis B virus (DHBV) has been a useful model for hepadnavirus infection. There have been few studies on immunity to DHBV and none describing the cell-mediated immune response by acute and chronically infected ducks. A duck hepatitis B antigen-specific blastogenesis assay was used to measure DHBV antigen-specific responses of duck peripheral blood (PBMC) and splenic mononuclear cells (SMCs) from uninfected control ducks, ducks acutely or chronically infected with DHBV, and ducks immune to DHBV. A comparison of the group mean responses by PBMC to DHBV surface antigen (DHBsAg) found that the immune group was significantly different to the other three groups (controls or unexposed, P < 0.0001; acutely infected, P< 0.01; chronically infected, P < 0.01). The responses to DHBsAg by PBMC of the acute group (P< 0.01) were significantly different also to that of the unexposed group. For DHBV core antigen (DHBcAg), significant differences in the responses were found between immune ducks and unexposed (P < 0.0005) and acutely infected (P < 0.05) groups. The SMC showed a significant difference between unexposed ducks and immune ducks (P< 0.05) in the group mean responses to DHBsAg. The responses to DHBcAg were significantly different between the immune group and the acute (P < 0.01) and unexposed (P < 0.01) groups. The group mean of unexposed ducks was also significantly different to that of acutely infected ducks (P < 0.01). This study indicates that the cellular immune response in immune animals differs from acutely and chronically infected ducks. Further studies of these differences may provide some explanations for the differing outcomes of DHBV infection.

Acute Disease↗
PubMed1999

[Detection of TTV DNA in liver tissue of patients with non A-G hepatitis].

OBJECTIVE: To study the existence of TTV (transfusion-transmitted virus) in liver tissue of patients with non A-G hepatitis. METHODS: 19 cases of paraffin-embedded liver tissues of the patients with non A-G hepatitis were studied by in sity hybridization with Dig-TTV DNA probe. RESULTS: Out of 19 cases, TTV DNA were detected in 6 cases, including 4 cases of acute mild hepatitis (30.80%) and 2 cases of chronic hepatitis (33.33%), respectively. Hybridization signals were detected within the nuclei or cytoplasm of the hepatocytes. The positive cells were scattered in the intralobular areas in acute mild hepatitis and more aggregated in periportal areas in chronic hepatitis. Among the 6 positive cases, 5 had a raised ALT. CONCLUSION: The result showed that the TTV detected in liver tissue of patients with unknown etiology is a novel virus, which belongs to an hepadnavirus.

Adult↗
PubMed1998

Preclinical investigation of L-FMAU as an anti-hepatitis B virus agent.

Preclinical aspects of a potent anti-hepatitis B virus (HBV) L-nucleoside, 1-(2-fluoro-5-methyl-beta-L-arabino-furanosyl)uracil (L-FMAU) are described. L-FMAU was prepared from L-ribose derivatives via either L-xylose or L-arabinose. L-FMAU shows potent antiviral activity against hepatitis B virus (EC50 5.0 microM in H1 cells) with high selectivity in vitro. L-FMAU is not incorporated into mitochondrial DNA and no significant lactic acid production was observed in vitro. L-FMAU is phosphorylated by thymidine kinase as well as deoxycytidine kinase, ultimately to the triphosphate, which inhibits HBV DNA polymerase as the mechanism of antiviral action. Preliminary in vivo toxological studies suggest no apparent toxicity for 30 days at 50 mg/kg/day in mice and for 3 months in woodchucks (10 mg/kg/day). L-FMAU also has respectable bioavailability in rats. L-FMAU shows potent anti-HBV activity in vivo against woodchuck hepatitis virus in chronically infected woodchucks and there is no significant virus rebound after cessation of the drug treatment.

Animals↗
PubMed2000

Detection of transfusion transmitted virus in hepatic and extra hepatic tissues using in situ hybridization.

OBJECTIVE: To investigate the location, distribution and significance of transfusion transmitted virus (TTV) in the liver and extra hepatic tissues. METHODS: A 123 bp fragment of TTV DNA within ORF(2) was amplified by PCR reaction and cloned into PCR2.1 vector. DNA sequencing revealed that the inserted fragment was highly isogenous with Japan ABO11494 strain. The inserted fragment was labeled with digoxigenin. Segment of liver, spleen, kidney, stomach and intestine tissues from 22 patients dead of liver diseases were detected by in situ hybridization with this digoxigenin labeled TTV DNA probe. RESULTS: TTV DNA was detected in 8 livers, 4 kidneys, 3 spleens, 2 intestines, and 2 stomachs. The positive cells of TTV DNA in livers were higher than that in other tissues. No obvious pathological topographical relationship of tissue inflammatory reaction with positive cells was found. CONCLUSION: TTV can infect hepatic and ex-hepatic tissues and may cause persistent infection.

Adolescent↗
PubMed2000

Impact of viral oncogenesis on responses to anti-cancer drugs and irradiation.

The view that chemical or physical oncogenesis and tumor therapy resistance represent different parts of common cellular alterations gained considerable attractiveness, because it explains the inherent unreponsiveness of many tumors. Viruses are potent oncogenes and are causally linked to approximately one-fifth of all human malignancies. Whether viral oncogenesis exerts comparable effects was less clear. Recent progress in experimental research provided ample evidence that viruses affect response of tumor cells toward anti-cancer drugs and irradiation. Resistance to cytostatic drugs and radiation develops by alterations at the drug-target sites (i.e., DNA or specific target proteins), upstream (i.e., detoxification mechanisms), or downstream of them (i.e., programmed cell death). Viruses interfere with specific cellular genes at these three levels. Viral proteins induce the expression and expression of drug resistance genes, that is, MDR1, DHFR, or CAD. Viral interactions with the tumor suppressor genes (p53, pRB) abrogate cell cycle arrests and disturb DNA repair of drug- and radiation-induced DNA lesions. The readiness to commit cellular suicide (apoptosis) is also affected by viral genes. The connection between viral oncogenesis and the response of tumor cells to treatment adds a new dimension to tumor biology and may have important consequences for oncological treatment modalities in the future.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Antiviral activities of penciclovir and famciclovir on duck hepatitis B virus in vitro and in vivo.

Chronic hepatitis B virus (HBV) infection is a major health problem worldwide. Antiviral strategies available at present, including interferon-alpha, have only limited efficacy, leading us to analyse the antiviral effects of penciclovir and famciclovir in the duck hepatitis B virus (DHBV) model of HBV infection in vitro and in vivo. In DHBV-infected duck hepatocytes, penciclovir effectively inhibited viral replication, with a concentration giving half-maximal inhibition of 0.25 microM. Furthermore, in vivo, penciclovir and its orally administered prodrug famciclovir strongly inhibited DHBV replication. These data demonstrate that penciclovir and famciclovir both have strong antiviral activities, and suggest that these agents might be useful for treating HBV infection in humans.

2-Aminopurine↗
PubMed2001

The role of duck hepatitis B virus and aflatoxin B1 in the induction of oxidative stress in the liver.

The aim of our study was to use the Pekin duck model to investigate the interactions between hepadnaviral infection and aflatoxin B1 (AFB1) exposure including the role of both factors in the induction of oxidative stress in the liver. AFB1 exposure of duck hepatitis B virus (DHBV) infected Pekin ducks induced a significant increase in viral replication associated with an intense biliary ductular cells proliferation. Interestingly, extremely high levels of AFB1-DNA adducts (40-120 pmol AFB1-Fapy/mg DNA) and AFB1-albumin adducts (1,500-3,000 pg AFB1-lys Eq/mg albumin) were detected in duck liver and serum respectively, as compared to other animal species exposed to a similar AFB1 dose. DHBV infection was found to induce a non-significant increase in AFB1-albumin adduct levels in duck serum. During the treatment duration there was no effect on formation of oxidative base damage within DNA and no effect on oxidative lipid peroxidation following either viral infection or AFB1 exposure. In terms of hepatic antioxidant enzymes (catalase, superoxide dismutase (SOD), glutathione peroxidase) a significant increase in SOD activity occurred following AFB1 exposure, but not DHBV infection, but this was observed only after the cessation of treatment, when biliary ductular cells proliferation was reduced.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2001

[Comparison of specific immune responses to duck hepatitis B virus in infected, immune, and uninfected ducks].

OBJECTIVE: To explore the factor in determining whether hepadnavirus infection is cleared or becomes chronic. METHODS: Experimental groups were established by inoculation with duck hepatitis B virus (DHBV) at different age and schedule. The kinetics of virus replication and the humoral and cell mediated immune response (CMI) by ducks acutely and chronically infected with, or immune to DHBV infection was measured. RESULTS: Infection of the adolescent animals with DHBV led to a transient viremia. The levels of anti-DHBs and anti-DHBc were higher in acutely infected group than in chronically infected group (P<0.05), but lower than in immune group (P<0.01). CMI analysis showed the response to DHBsAg and DHBcAg by peripheral blood mononuclear cells from acutely infected ducks (10 day pi) was stronger than that from chronically infected ones (P<0.05); however, the level of the response reduced over a period of 5 weeks. There were no differences regarding CMI response in acutely infected or immune ducks. CONCLUSIONS: The immune response especially antigen -specific immune response is the key factor in determining the outcome of the infection.

Animals↗
PubMed2001

[Experimental study on the effect of combination therapy with lamivudine and famciclovir against duck hepatitis B virus in vivo].

OBJECTIVE: To study the antiviral effect of combination therapy with the nucleoside analog lamivudine and famciclovir on duck hepatitis virus (DHBV) in vivo. METHODS: The Chongqing duck hepatitis B model was treated with lamivudine and famciclovir by intragastric administration for 4 weeks. DHBV DNA and DHBsAg in serum were observed by serum dot-blot hybridization and ELISA. ALT and AST in serum were also detected. Histological observation on the duck liver was done simultaneously. The trial was contrasted with a single acyclovir (ACV), famciclovir (FCV), or Lamivudine (3TC). RESULTS: Combination therapy with Lamivudine and famciclovir could significantly reduce the serum DHBV DNA level. After stopping the treatment for 1 week, serum DHBV DNA level did not return significantly. The change of DHBsAg was similar to DHBV DNA. The level of ALT, AST, and the features of liver histopathology in combination-treated ducks were not different from those in control ducks. CONCLUSIONS: The study confirms that combination therapy is superior to single antiviral agent in vivo for ducks with chronic DHBV carrier.

2-Aminopurine↗
PubMed2000

[Experimental study of shuangcao granule no. 1 on duck hepatitis B virus in ducklings].

OBJECTIVE: To study the in vivo anti-viral effect of a Chinese drug, composite Shuangcao Anti-Jaundice Granule No. 1(SCG-1), on duck hepatitis B virus (DHBV). METHODS: Guangzhou brown spot ducklings infected with DHBV were used as the hepatitis B animal model, for which, 1-day old ducklings were infected with DHBV. Positive DHBV-DNA in ducklings sera were detected 13 days after the infection, and then SCG-1 was given for 14 days and DHBV-DNA was detected by dot-blot hybridization test. RESULTS: After medicated with SCG-1 [10 g/(kg.day) and 5 g/(kg.day)] 7 days and 14 days, optic density value (OD value) of DHBV-DNA in ducklings' sera were obviously lower than that before treatment, there was significant difference. But rebound phenomenon appeared in both groups 3 days after stopping medication (P < 0.05). CONCLUSION: SCG-1 could inhibit the replication of DHBV-DNA in Guangzhou ducklings.

Animals↗