Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Hepadnaviridae”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

334 records · Page 19Linked to original sources
PubMed1994

Characterization of the antiviral effects of 2' carbodeoxyguanosine in ducks chronically infected with duck hepatitis B virus.

This study was carried out to evaluate benefits and limitations of long-term therapy of hepatitis B virus infections with a nucleoside analog inhibitor of virus replication. The model we used was the domestic duck chronically infected with duck hepatitis B virus by in ovo infection. 2' Carbodeoxyguanosine was used as an inhibitor of viral DNA synthesis. In all animals examined there was a reduction in virus production during therapy. A dose of 2' carbodeoxyguanosine of 10 micrograms/kg every other day reduced the number of infected hepatocytes from greater than 95% to 25% to 50% in less than 3 mo, whereas a 10-fold higher dose produced a decline to less than 10%. Histological evaluation revealed mild to moderate liver injury in ducks receiving the higher dose of 2' carbodeoxyguanosine, suggesting that disappearance of infected hepatocytes may have been accelerated by a toxic effect of the drug. Drug treatment did not completely eliminate duck hepatitis B virus from any duck, and replication was restored in all hepatocytes within a few weeks to several months after antiviral therapy was terminated. Our results suggest that elimination of a chronic infection with a single inhibitor of replication may be difficult in a host that lacks an antiviral immune response capable of eliminating at least a portion of the infected hepatocytes and of ultimately producing antibodies capable of neutralizing residual virus.

Animals↗
PubMed1993

[Clinical and experimental study on yi-gan-ning granule in treating chronic hepatitis B].

This paper reports that 320 patients with chronic hepatitis B (CHB) were treated with Yi-ganning Granule (YGNG) and the pharmacodynamics of YGNG in the animal study. As control, another 70 patients with CHB receiving oleanolic acid granule (OAG) were compared to 68 patients in YGNG group. YGNG is consisted of Astragalus membranaceus , Artemisia capillaris, Codonopsis pilosula, et al. Each patient has taken YGNG or OAG for 3 months. The result showed YGNG was effective on recovering the liver function and OAG had similar effect. The sero-negative conversion rates of HBsAg, HBeAg, HBcAb and positive conversion rate of HBeAb in the YGNG group were 33.1%, 40.5%, 10.5% and 15.5% respectively, which were much better than that in OAG group (P < 0.05-0.001). The result of 6 months follow up showed that 60 of 62 patients receiving YGNG were in stabilized state. The result in the animal study demonstrated that YGNG had significant protection from the liver damage caused by CCl4. YGNG could decrease serum ALT level and protect the liver function of carbohydrate, fat, protein metabolism and detoxication. YGNG could induce interferon in vivo and play an important role in seroconversion of negative DHBV-DNA and improvement of pathological morphology in viral hepatitis B.

Adolescent↗
PubMed1993

[The effects of Ara-A on viral markers in duck hepatitis B virus carrier ducks].

Duck hepatitis B virus (DHBV) carrier ducks of one week old were injected with Ara-A (adenine arabinoside) of different dose including 2.5 (11 ducks), 5.0 (11), 10.0 (10) and 20.0 (10) mg/kg for 14 days. This antiviral effect showed dose-dependence up to 5.0 mg/kg and this dose seemed effective to obtain significant antiviral effect. Viral DNA and DNA polymerase activity were reduced significantly from the 1st week after starting the administration of Ara-A. This antiviral effect was maintained even at the 1st week after discontinuation of the drug. These findings were quite similar to those observed in HBV carriers. With the increasing necessity of Ara-A treatment in patients who will not respond to interferon therapy, DHBV seemed a suitable model for the investigation of the dose and antiviral effect of Ara-A treatment in humans.

Animals↗
PubMed1993

Coordinate expression of N-myc 2 and insulin-like growth factor II in precancerous altered hepatic foci in woodchuck hepatitis virus carriers.

Over 50% of the hepatocellular carcinomas (HCCs) arising in the livers of woodchucks with persistent woodchuck hepatitis virus (WHV) infection contain integrations of WHV DNA within, or immediately adjacent to, a unique and functional N-myc 2 retroposon [G. Fourel et al., Nature (Lond.), 347: 294-298, 1990; Y. Wei et al., J. Virol., 66: 5265-5276, 1992]. The integrations are believed to activate the expression of N-myc 2 by an enhancer insertion mechanism [Y. Wei et al., J. Virol., 66: 5265-5276, 1992]. Since the fetal growth factor insulin-like growth factor II (IGF-II) is also expressed in woodchuck HCCs [X. X. Fu et al., J. Virol., 62: 3422-3430, 1988; D. Yang and C. E. Rogler, Carcinogenesis (Lond.), 12: 1893-1901, 1991] we sought to determine the earliest stage in hepatocarcinogenesis at which overexpression of N-myc and IGF-II could be detected. The earliest precancerous lesions so far identified in woodchucks are altered hepatic foci (AHFs) [K. Abe et al., Jpn. J. Cancer Res., 79: 466-472, 1988; H. Popper et al., Hepatology (Baltimore), 1: 91-98, 1981]. Using in situ hybridization, we have demonstrated that both the N-myc and IGF-II genes are coordinately overexpressed in nearly all AHFs in precancerous woodchuck livers. In contrast, WHV replication was either repressed or undetectable in the same AHFs. The use of probes selective for N-myc 2 versus N-myc 1 (the normal mammalian homologue) revealed nearly exclusive expression of N-myc 2 in AHFs. Cells within AHFs were generally slow growing, as determined by frequency of histone III-expressing hepatocytes; however, a few fast-growing AHFs, with growth rates nearly equivalent to those of HCCs, were identified. Furthermore, very highly elevated N-myc 2 or IGF-II expression was detected in a few subregions within AHFs which otherwise exhibited a uniformly moderate expression, suggesting that selection for higher levels of N-myc or IGF-II expression may occur within AHFs. These data suggest that coordinate expression of N-myc 2 and IGF-II and repression of WHV replication may be functionally involved in the development of AHFs and that cells expressing very high levels of N-myc and IGF-II may be selectively enriched as AHFs progress to HCC, since high levels of N-myc and IGF-II are common in HCCs.

Animals↗
PubMed1993

The effects of using recombinant vaccinia viruses expressing either large or small HDAg to protect woodchuck hepadnavirus carriers from HDV superinfection.

Live rVVs expressing either p24 delta or p27 delta were produced and used to immunize woodchuck hepadnavirus carriers. Upon challenge with infectious HDV, circulating HDV RNA levels appeared to be similar in both controls and vaccinees. Although extended follow-up studies of these animals is necessary before making firm conclusions, including an analysis of circulating HDAg levels, these preliminary results provide no evidence for a protective immunity conferred by the rVVs. In contrast, we have shown in other studies that repeated immunization of woodchucks with purified, recombinant p24 delta subunit does confer significant protection against HDV challenge in some of the vaccinees (A. Ponzetto, et al., this volume). The underlying immunological mechanisms responsible for the different outcome of these varied vaccination regimens remain to be elucidated.

Animals↗
PubMed1996

A functional N-myc2 retroposon in ground squirrels: implications for hepadnavirus-associated carcinogenesis.

Three hepatitis B viruses infecting humans, woodchucks and ground squirrels increase the risk of hepatocellular carcinoma in their respective hosts. The woodchuck hepatitis B virus (WHV), unlike the two other viruses, induces a rapid carcinogenic process characterized by direct activation of myc proto-oncogenes by insertion of viral DNA. The highly preferred target of insertional mutagenesis in woodchucks is N-myc2, an intronless N-myc gene. Strikingly, N-myc2 has no human homolog and the homologous N-myc2 locus previously detected in the ground squirrel genome, remains silent during hepatocarcinogenesis. Therefore, N-myc2 may represent a critical host determinant in the evolution of the disease associated with hepadnavirus infection. To address this question, we performed a structural and functional analysis of the ground squirrel N-myc2 locus. We show that ground squirrel N-myc2 is highly homologous to its woodchuck counterpart and is a functional proto-oncogene. Existence of a functional N-myc2 gene as a potential target for insertional activation by viral DNA is therefore not restricted to the woodchuck species. This suggests that viral rather than host factors determine the higher oncogenic phenotype of WHV as compared to the two other mammalian hepadnaviruses.

Amino Acid Sequence↗
PubMed1996

A splice hepadnavirus RNA that is essential for virus replication.

According to the current model of hepadnavirus gene expression, the viral envelope proteins are produced from unspliced subgenomic RNAs, in contrast to the retroviral mechanism, where the subgenomic env RNA is generated by RNA splicing. We now describe and characterize a novel duck hepatitis B virus RNA species which is derived from the RNA pregenome by loss of a 1.15 kb intron. This RNA (termed spliced L RNA) codes for the large surface protein (L protein), as does the previously described unspliced mRNA (the preS RNA); however, it differs in 5' leader sequence and promoter control. Mutational analysis indicates that the spliced L RNA is functionally important for virus replication in infected hepatocytes and ducks, but not for virus formation from transfected DNA genomes. This suggests that the newly discovered second pathway for L protein synthesis plays a distinct role in an early step in the viral life cycle.

Animals↗
PubMed1995

The role of recombinant human fusion protein IL-6/IL-2 (CH925) in hepadna virus infection treatment.

The effects of CH925, a novel immune modulator, on hepadna virus infection was evaluated. Day-old ducklings were inoculated intravenously with LJ-76 DHBV containing serum. Infected ducklings were then treated with the CH925 and the mixture of IL-2 and IL-6 intravenously and the control ducklings received equivalent normal saline (NS). Blood and liver samples were taken and assayed for DHBV DNA and/or DHBsAg. At the completion of the experiment there was a inhibition of viremia with the CH925 and IL-2 + IL-6. Serum DHBV DNA was detected in 6 of 10 ducks in 100,000 unit/kg dosage group, 7 of 10 ducks in 50,000 unit/kg dosage group and 6 of 10 ducks in IL-2 + IL-6 dosage group, compared with 9 of 10 NS control, and it showed a similar result in circulating DHBsAg. When samples of liver DNA were processed for hybridization, a little difference in the DHBV DNA replication was noted between ducks receiving CH925, IL-2 + IL-6 or NS placebo. It is suggested that CH925 might be a potential remedy in HBV infection treatment.

Animals↗
PubMedDate not supplied

Recombinant vaccinia virus expressing Pre-S/S protein of duck hepatitis B virus and its preliminary use for treatment of persistent infection.

The envelope (Pre-S/S) gene of duck hepatitis B virus (DHBV) was amplified by polymerase chain reaction (PCR) and cloned into plasmid pGJP5, under the control of vaccinia virus promoter P(7.5). By recombination in cell culture, and screened in human TK- 143 cells in the presence of 5-bromouracil deoxyriboside (5-BUdR), a recombinant vaccinia virus, bearing the envelope gene of DHBV (pGDHBV-5) which could replicate in cell cultures was constructed. DHBV surface antigen (DHBsAg) was detected in pGDHBV-5-infected cell lysate by dot enzyme immunoassay (EIA). After multiple-site intradermal injections of pGDHBV-5, DHBsAg could be detected in the serum of immunized adult ducks. This indicated that the recombinant virus replicated and expresed DHBsAg in ducks. The recombinant virus was used as a therapeutic vaccine to immunize persistently DHBV-infected ducks. After immunization, a transient significant decrease of serum DHBsAg was observed.

Animals↗
PubMed1997

[Clinical and experimental study on treatment of chronic hepatitis B with yanggan aoping mixture].

OBJECTIVE: To assess the efficacy of Yanggan Aoping Mixture (YGAPM) in treating hepatitis B. METHODS: Patients suffered from chronic hepatitis B were treated with YGAPM. Observe their short- and long-term efficacy and the change of serum hepatitis B virus marker. In experiment, the effect of YGAPM in treating rat's liver injury as well as HBV-infected tree shrew and duck HBV-infected ducks was observed. RESULTS: In 79 cases of chronic persistant hepatitis, the markedly effective rate was 60.76%, and follow-up studies on 40 cases, the further rasied to 70.00%. In 73 cases of chronic active hepatitis, the markedly effective rate was 60.27%, and further raised to 62.50% in 32 follow-up cases. In the treatment group, 85 (71.43%) of the 119 cases with HBeAg-positive turned to negative. Whereas in the control group, only 40 (44.94%) of 89 HBeAg-positive cases turned to negative, P < 0.01. Results of experimental study showed that negative conversion rate of tree shrew infected with HBV marker was raised, while infected duck blood with duck HBV DNA was inhibited. Those compared with the control group separately, the difference was remarkably significant. CONCLUSIONS: YGAPM is an effective drug in treating chronic hepatitis B, and it could effectively negative convert the HBV marker.

Adolescent↗