| duck hepatitis b virus polymerase produced by in vitro transcription and translation possesses dna polymerase and reverse transcriptase activities. | activities of the hepadnavirus polymerases are known to include those of dna polymerase, reverse transcriptase and rnase h. to date, it has been difficult or impossible to clone and express the product as an active enzyme. in this study, full length capped rna encoding duck hepatitis b virus (dhbv) polymerase was produced by in vitro transcription from a t7 promoter. the rna was translated in a rabbit reticulocyte lysate system and produced an 35s-methionine labelled 79 kd band on sds-polyacryla ... | 1992 | 1281990 |
| [uses of duck hepatitis b virus polymerase and reverse transcriptase in the evaluation of anti-hepatitis b virus drugs]. | the method of dhbv replication complexes (rcs) purification was modified. in order to screen anti-hbv drugs from chinese medicinal herbs, the inhibitory effects of the extracts of 14 chinese recipes and herbs, 30 compounds isolated from chinese herbs on dhbv dna polymerase (dnap) and reverse transcriptase (rt) have been studied. the results showed that extracts of xiao chai hu tang (small bupleurum decoction) inhibited dhbv dnap and rt in less extent. of the 7 herbs, the components of xiao chai ... | 1992 | 1282399 |
| [the inhibitory effects of catechin derivatives on the activities of human immunodeficiency virus reverse transcriptase and dna polymerases]. | catechin derivatives including (-)-epicatechin gallate (ecg), (-)-epigallocatechin gallate (egcg), (-)-epigallocatechin (egc) and green tea extract (gte) were found to inhibit the activities of cloned human immunodeficiency virus type 1 reverse transcriptase (hiv-1 rt), duck hepatitis b virus replication complexes reverse transcriptase (dhbv rcs rt), herpes simplex virus 1 dna polymerase (hsv-1 dnap) and cow thymus dna polymerase alpha (ct dnap alpha). egcg and ecg were shown to be very potent i ... | 1992 | 1284389 |
| naturally occurring point mutation in the c terminus of the polymerase gene prevents duck hepatitis b virus rna packaging. | a duck hepatitis b virus (dhbv) genome cloned from a domestic duck from the people's republic of china has been sequenced and exhibits no variation in sequences known to be important in viral replication or generation of gene products. intrahepatic transfection of a dimer of this viral genome into ducklings did not result in viremia or any sign of virus infection, indicating that the genome was defective. functional analysis of this mutant genome, performed by transfecting the dna into a chicken ... | 1992 | 1309904 |
| inhibition of hepatitis b virus production by modified 2',3'-dideoxy-thymidine and 2',3'-dideoxy-5-methylcytidine derivatives. in vitro and in vivo studies. | the effect of analogues of both 2',3'-dideoxy-3'-fluorothymidine (fddthd) [2',3'-dideoxy-3'-fluorouridine (fddurd), 2',3'-dideoxy-3'-fluoro-5-chlorouridine (fddclurd), 2',3'-dideoxy-3'- fluoro-5-bromouridine (fddbrurd) and 2',3'-dideoxy-3'-fluoro-5-bromovinyluridine (fddbvurd)] and 2',3'-dideoxy-3'-fluorocytidine (fddcyt) [2',3'-dideoxy-3'-fluoro-5-fluorocytidine (fddfcyt), 2',3'-dideoxy-3'-fluoro-5-chlorocytidine (fddclcyt), 2',3'-dideoxy-3'-fluoro-5-methylcytidine (fddmecyt), 2',3'-dideoxy-3'- ... | 1992 | 1314607 |
| validation of virus inactivation by heat treatment in the manufacture of diaspirin crosslinked hemoglobin. | diaspirin crosslinked hemoglobin (dclhb), a hemoglobin based oxygen carrying solution prepared from outdated human blood, is subjected to a heat treatment step to inactivate viruses in our manufacturing process. to validate the efficacy of this inactivation, we have simulated the heat treatment procedure at a reduced scale using hemoglobin solution spiked with representative viruses. human immuno-deficiency virus (hiv), cytomegalovirus (cmv), and duck hepatitis b virus (dhbv) were used in this v ... | 1992 | 1327242 |
| duck hepatitis b virus infection and duck hepatocellular carcinoma. | to study the relationship between duck hepatitis b virus (dhbv) infection and duck hepatocellular carcinoma (dhcc), histological examination and dhbv dna hybridization were performed in 875 ducks from three flocks in qidong county. among them, 34 suffered from hepatoma, including 23 hepatocellular carcinoma, 8 cholangiocarcinoma and 3 hepatocellular-cholangiocarcinoma. of the 34 ducks with hepatoma 27 were positive for dhbv dna in the liver and/or serum. dhbv dna was demonstrated in neoplastic n ... | 1992 | 1327668 |
| the role of hepatitis b virus in the development of primary hepatocellular carcinoma: part i. | chronic infections with hepatitis b virus (hbv) of humans and animal hepadnavirus infections in their natural hosts are strongly associated with primary hepatocellular carcinoma (hcc). although viral integrations are found in cells of many hcc, no general viral-specific hepatocarcinogenic mechanism for hepadnaviruses has been identified. in approximately one half of hcc in woodchuck hepatitis virus (whv) infected woodchucks, viral integrations near the c-myc or n-myc genes have been reported whi ... | 1992 | 1336678 |
| the sequential change of serum 2',5' oligoadenylate synthetase in different infectious patterns of duck hepatitis b virus in ducks in experimental transmission. | duck hepatitis b virus (dhbv) shows clear age-dependent infectious patterns like that of hepatitis b virus, and many factors have been assumed to have a role in the persistence of the infection. in the present study, the activities of the interferon-induced enzyme 2',5' oligoadenylate synthetase (2,5as) were observed sequentially in the serum of ducks experimentally infected with dhbv on posthatch days 1, 7 and 14. these were compared with the infectious pattern to investigate whether the endoge ... | 1992 | 1378031 |
| elimination of immune tolerance to hepatitis virus in an animal model. | four-day old ducklings were infected with duck hepatitis b virus to simulate perinatal transmission of hepatitis b virus. immune tolerance was characterized as persistent viremia, antigenemia, without detection of anti-dhbs or anti-dhbc. a synthetic peptide, p125-146, mimicking one of the epitopes of the native dhbv pre-s protein was used to cross-link to tetanus toxoid or phytohemagglutinin. these 'novel' antigens were used to immunize immune tolerant ducks, aimed at bypassing t cell tolerance. ... | 1992 | 1395838 |
| ultrastructural study on extrahepatic infection of duck hepatitis b virus in ducks. | kidney and pancreas tissues from congenitally infected ma ducks with duck hepatitis b virus (dhbv) were examined by immunohistochemical staining technique and electron microscopy. the immunostaining showed that dhbv antigen was localized in the cytoplasm of tubular epithelial cells of kidney and acinar cells of pancreas of infected ducks. under electron microscope, we found that complete and incomplete dhbv particles existed in the dilated cisternae of rough endoplasmic reticulum of both the cel ... | 1992 | 1395841 |
| effects of phyllanthus plant extracts on duck hepatitis b virus in vitro and in vivo. | the effects of extracts of five australian phyllanthus species (p. hirtellus, p. gunnii, p. gasstroemii, p. similis and p. tenellus), other plant extracts and the antiviral drug foscarnet on duck hepatitis b virus (dhbv) endogenous dna polymerase (dnap) activity were compared. all 5 phyllanthus species caused 50% inhibition at concentrations of dry weight between 350-800 micrograms/ml, which is comparable with the effect described for p. amarus on the dnap of human and woodchuck hepatitis b viru ... | 1992 | 1416905 |
| [a study of duck hepatitis b virus infection in chinese ducklings]. | intraperitoneal inoculation of duck hepatitis b virus in three different dosages (9 x 10(7), 1.8 x 10(8), 9 x 10(8) dhbv particles) into 3 to 21 day-old chinese ducklings provided from a dhbv free flock produced a persistent infection up to 93.3% in 60 animals. the serum and liver specimens of these ducklings were examined by dna dot blot hybridization on the 30th day after inoculation. the results showed that: (1) examination of viral dna in liver was more sensitive and reliable than estimation ... | 1992 | 1477940 |
| cloning of hepadnaviruses using microquantity serum. | | 1992 | 1508732 |
| duck hepatitis b virus infection of hepatocytes is not dependent on low ph. | the ph dependency for initiation of infection by the hepadnavirus duck hepatitis b virus (dhbv) was investigated in primary duck hepatocytes. first, an infection assay was developed using a radioimmunoblot to measure dhbv e antigen secreted into tissue culture fluid from infected hepatocytes. the quantity of this viral marker was proportional to the duration of inoculation and the amount of dhbv used as inoculum. the role of ph in initiation of dhbv infection was investigated by using this assay ... | 1992 | 1560528 |
| replication of dhbv genomes with mutations at the sites of initiation of minus- and plus-strand dna synthesis. | we have examined the consequences on duck hepatitis b virus dna synthesis of deleting the 5' and 3' copies of the 12 base sequence, dr1, from the viral pregenome. with the wild-type virus, reverse transcription initiates at nt 2537 within the 3' copy of dr1. when this sequence was deleted, initiation of reverse transcription was found at two other sites located closer to the 3' end of the pregenome (nt 2576 and nt 2644). the 3-base motif uua was the only sequence common to these sites as well as ... | 1992 | 1566574 |
| [attempt to cause hepatitis in duck hepatitis b virus carrier ducks by immunization with dhbv protein]. | in order to investigate the hypothesis that viral hepatitis is a host immune response against viral protein presented on hepatocytes, we attempted to cause hepatitis in dhbv carrier ducks by immunization with dhbv protein. while ducks injected with freund complete adjuvant (fca) showed only weak hepatitis, those immunized with dhbv particle protein showed severe hepatitis. this same procedure could not cause significant inflammation in the liver of ducks without dhbv infection. the severity of h ... | 1992 | 1619786 |
| effects of 2'-fluorinated arabinosyl-pyrimidine nucleosides on duck hepatitis b virus dna level in serum and liver of chronically infected ducks. | the 2'-fluorinated arabinosyl-pyrimidine nucleosides, 1-(2'-deoxy-2'-fluoro-beta-d-arabinofuranosyl)-5-iodocytosine (fiac) and 1-(2'-deoxy-2'-fluoro-beta-d-arabinofuranosyl)-5-methyluracil (fmau), are new antiviral compounds with in vitro inhibitory activity against the dna polymerase of hepadnaviruses. those compounds also induced permanent inhibition of viral replication in woodchucks chronically infected by woodchuck hepatitis virus. the effects of these antiviral compounds were assessed in d ... | 1992 | 1629711 |
| [duck hepatitis b virus dna in multiple primary cancers and metastatic tumors in duck liver]. | duck hepatitis b virus (dhbv) dna was detected in both multiple primary cancers and intrahepatic metastatic tumors in duck liver by southern blot technique. among 7 ducks with multiple primary tumors in the liver, the banding pattern of integrated dhbv dna in different tumors was identical in 3 animals but different in 2. one duck showed a similar hybridization pattern in different tumor nodules and the remaining one was negative for dhbv dna. integrated dhbv dna was also identified in one duck ... | 1991 | 1652415 |
| a technique for liver biopsy performed in pekin ducks using anesthesia with telazol. | infection of pekin ducks with duck hepatitis b virus is a useful model for studying the hepadenoviruses, of which human hepatitis b virus is the prototype. the utility of this model has been limited, however, by the difficulties associated with anesthetizing and obtaining liver biopsies from ducks. we developed a technique using telazol (13 mg/kg) to anesthetize ducks before surgical biopsy of the liver in ducks infected with duck hepatitis b virus. eight pekin ducks infected with duck hepatitis ... | 1991 | 1666151 |
| [duck hepatitis b virus (dhbv) and viral dna in duck hepatocellular carcinoma and liver tissue]. | the hybridization test for duck hepatitis b virus dna was performed in 34 ducks with hepatoma from qidong, jiangsu province. among the 34 hepatoma ducks, 18 were positive for dhbv dna in the serum and 27 were positive in the tumor and/or liver tissue. tissue sections were stained with victoria blue nuclear fast red for detecting dhbv surface antigen. victoria blue positive cells were found in 11 tumors and 15 paratumorous regions of 23 ducks with hepatocellular carcinoma. although paratumorous r ... | 1991 | 1666870 |
| inhibition of duck hepatitis b virus replication in vitro by 2',3'-dideoxy-3'-azidothymidine and related compounds. | we have adopted the in vitro hepatocyte culture system of the duck infected with duck hepatitis b virus (hdbv) to an anti-viral assay system. using this method, we found that 2',3'-dideoxy-3'-azidothymidine (n3dt) and 2',3'-dideoxy-3'-o-methylthymidine (omet) had antiviral effects against dhbv replication in the concentrations of 20-50 mumol/l and 4-40 mumol/l, respectively. the n3dt inhibited the single strand dna formation (negative strand), which is an intermediate of virus replication. howev ... | 1991 | 1688076 |
| virus-neutralizing monoclonal antibody to a conserved epitope on the duck hepatitis b virus pre-s protein. | in this study we used duck hepatitis b virus (dhbv)-infected pekin ducks and heron hepatitis b virus (hhbv)-infected heron tissue to search for epitopes responsible for virus neutralization on pre-s proteins. monoclonal antibodies were produced by immunizing mice with purified dhbv particles. of 10 anti-dhbv specific hybridomas obtained, 1 was selected for this study. this monoclonal antibody recognized in both dhbv-infected livers and viremic sera a major (36-kilodalton) protein and several min ... | 1990 | 1689393 |
| polymerase gene products of hepatitis b viruses are required for genomic rna packaging as wel as for reverse transcription. | all reactions involving reverse transcription of rna are segregated from the cytosol within a subviral particle or capsid composed of the major capsid protein, the polymerase and the rna template. a key step in the formation of these particles is the selective encapsidation of the rna template. although an important general feature of the reverse transcription pathway, encapsidation has been carefully studied only for retroviruses. we have now examined the encapsidation reaction in a family of e ... | 1990 | 1690862 |
| epitope-specific antibody response to the surface antigen of duck hepatitis b virus in infected ducks. | in order to investigate the immune response to duck hepatitis b virus (dhbv) infection, newly hatched dhbv dna negative ducklings were injected with infectious serum of sufficiently low dhbv-dna titer to allow clearance of viremia. of 20 injected ducklings, 13 (65%) became viremic. of these, 6 (46%) cleared virus from the serum 3 to 22 weeks postinjection. the convalescent sera of these 6 animals were tested for an epitope-specific antibody response in a highly specific competitive inhibition as ... | 1990 | 1693247 |
| mechanism of translation of the hepadnaviral polymerase (p) gene. | unlike many other reverse transcriptase genes, the polymerase (p) gene of the hepatitis b viruses is expressed by translational initiation from its own aug codon rather than by ribosomal frameshifting during translation of the overlapping core gene (c). to explore the mechanism of its translation, we have fused the p gene of duck hepatitis b virus to the bacterial lacz gene at a point 3' to the c-p overlap; this allows detection of the products of p translation with antisera to the lacz-encoded ... | 1990 | 1695011 |
| antiviral strategies in chronic hepatitis b virus infection: ii. inhibition of duck hepatitis b virus in vitro using conventional antiviral agents and supercoiled-dna active compounds. | primary duck hepatocyte (pdh) cultures, congenitally infected with the duck hepatitis b virus (dhbv), were grown on feeder cell layers of irradiated human embryonic lung fibroblasts and then exposed to a number of compounds with recognized or potential antiviral activity. these compounds included conventional antiviral agents, reverse transcriptase inhibitors, compounds with activity to supercoiled-dna, and dna-binding agents. twenty-three compounds were evaluated, and 13 were found to inhibit s ... | 1990 | 1696959 |
| effects of insertional and point mutations on the functions of the duck hepatitis b virus polymerase. | the polymerase (p) gene of hepadnaviruses encodes a large polypeptide that appears to participate in several steps in the viral life cycle: packaging of viral rna, providing the primer for synthesis of minus-strand dna, synthesizing minus-strand dna from an rna template and plus-strand dna from a dna template, and degrading viral rna in rna-dna hybrids. to assist in the assignment of these functions to domains of the duck hepatitis b virus polymerase protein, we have constructed a series of subs ... | 1990 | 1698997 |
| peptide mapping of neutralizing and nonneutralizing epitopes of duck hepatitis b virus pre-s polypeptide. | antibodies to the envelope proteins of duck hepatitis b virus neutralize viral infection in vitro. using a library of murine monoclonal antibodies (mabs) against the envelope proteins, we previously identified four neutralizing and two non-neutralizing epitopes on the pre-s region of the large envelope proteins. in this study we report the localization of all but one of these epitopes at the amino acid level. all but 28 nucleotides of the pre-s and s genes were cloned in puc vectors and expresse ... | 1991 | 1704654 |
| mutations affecting hepadnavirus plus-strand dna synthesis dissociate primer cleavage from translocation and reveal the origin of linear viral dna. | hepadnaviruses replicate their circular dna genomes via reverse transcription of an rna intermediate. the initial product of reverse transcription, minus-strand dna, contains two copies of a short direct repeat (dr) sequence, termed dr1 and dr2. plus-strand dna synthesis initiates at dr2 on minus-strand dna, using as a primer a short, dr1-containing oligoribonucleotide derived by cleavage and translocation from the 5' end of pregenomic rna. to clarify the sequence requirements for plus-strand pr ... | 1991 | 1704925 |
| evidence that less-than-full-length pol gene products are functional in hepadnavirus dna synthesis. | duck hepatitis b virus mutants containing frameshift or stop codon mutations in a portion of the viral pol gene separating the terminal protein and reverse transcriptase domains had a leaky phenotype and, depending on the location and type of mutation, synthesized up to 10% as much viral dna as did the wild type. this region of the pol gene had previously been reported to be refractory to missense mutations; in fact, the leakiness of most of our mutants appeared attributable to translational sup ... | 1991 | 1707980 |
| in vivo neutralization of duck hepatitis b virus by antibodies specific to the n-terminal portion of pre-s protein. | the neutralization of duck hepatitis b virus (dhbv) infection using antibodies directed against the n-terminal portion of the large surface protein was examined in vitro and in vivo. we demonstrate here that a monoclonal antibody, directed against an epitope mapped between aa 77 and aa 100 on the dhbv pre-s, exerts a similar neutralizing activity (77%) both in vivo and in vitro. furthermore, we have found that a polyclonal antiserum raised against the bacterially expressed 131 first amino acids ... | 1991 | 1718087 |
| human non-hepatocytes support hepadnaviral replication and virion production. | the competence of non-hepatocytes to support hepatitis b virus (hbv) gene expression and replication was studied by transient transfection of various human cell lines with a head-to-tail dimer of hbv dna. independent of their neuroectodermal, mesenchymal or epithelial origin, all non-hepatocyte cell lines tested synthesized and secreted hepatitis b surface antigen (hbsag) and hepatitis b core/e antigen (hbc/eag). further analyses of two of these cell lines (ls 180 and colo 320) identified the tw ... | 1992 | 1730939 |
| intracellular factors, but not virus receptor levels, influence the age-related outcome of dhbv infection of ducks. | previous serological studies of experimental infection with duck hepatitis b virus (dhbv) have shown that the outcome of infection depends largely on the age of the duck at the time of inoculation. to examine the hypothesis that decreased susceptibility with increased age might be due to the loss of the virus receptor on hepatocyte membranes in adult ducks, we performed receptor binding studies using intact serum-derived dhbv virions and purified liver plasma membranes from both young ducklings ... | 1992 | 1733100 |
| rapid resolution of duck hepatitis b virus infections occurs after massive hepatocellular involvement. | a study was carried out to determine some of the factors that might distinguish transient from chronic hepadnavirus infection. first, to better characterize chronic infection, pekin ducks, congenitally infected with the duck hepatitis b virus (dhbv), were used to assess age-dependent variations in viremia, percentage of dhbv-infected hepatocytes, and average levels of dna replication intermediates in the cytoplasm and of covalently closed circular dna in the nuclei of infected hepatocytes. level ... | 1992 | 1738197 |
| sulfated polyanions do not inhibit duck hepatitis b virus infection. | on the basis of the antiviral action of sulfated polyanions in human immunodeficiency virus and other viral infections, we studied the effect of dextran sulfate and heparin on duck hepatitis b virus infection. these agents do not affect viral uptake and replication in liver cells in vitro or in vivo. sulfated polyanions, therefore, appear to have no potential for the treatment of hepadnavirus infections. | 1991 | 1804020 |
| effects of purine nucleoside analogues with a cyclobutane ring and erythromycin a oxime derivatives on duck hepatitis b virus replication in vivo and in cell culture and hiv-1 in cell culture. | the effects on duck hepatitis b virus (dhbv) replication of specific analogues of two classes of chemical compounds not previously tested against hepadnaviruses are described. one is erythromycin a-9-methyloxime (emo) and other oxime derivatives of erythromycin a, and the other is purine nucleoside analogues (cyclobut a and cyclobut g) with cyclobutane rings. viral replication was assessed by measuring serum levels of dhbv dna in infected ducklings and dhbv dna in infected primary duck hepatocyt ... | 1991 | 1804929 |
| [ultrastructural study and localization of duck hepatitis b virus in the livers of experimentally infected ducks]. | an electron microscopic study was performed to investigate the occurrence and localization of duck hepatitis b virus (dhbv) in the livers of infected beijing ducks. dhbv-dna was found in trace amounts in liver extract on 9th hours after infection by southern blot hybridization and was found in serum on the 4th day of infection. virus particles were recognized in the hepatocytes as early as the 3rd day of infection. many incomplete virus particles, (50 to 80 nm in diameter), and a few complete vi ... | 1991 | 1831706 |
| comparative sequence analysis of defective and infectious avian hepadnaviruses. | | 1991 | 1840663 |
| characterization of the core promoter and enhancer of duck hepatitis b virus. | the core gene promoter of duck hepatitis b virus (dhbv) has been localized and an enhancer element has been found in a region of the dhbv genome immediately upstream of the core promoter. this enhancer was able to activate expression from both the core promoter and the s promoter of dhbv, as well as from the heterologous thymidine kinase and simian virus 40 early promoters, but not from the dhbv pres promoter, which was active both in the absence and in the presence of the enhancer. the activity ... | 1991 | 1871970 |
| infection initiated by the rna pregenome of a dna virus. | we describe experiments demonstrating that after transfection into permissive cells, the rna pregenome of an avian hepadnavirus, the duck hepatitis b virus, is infectious. using a sindbis virus expression vector, we showed that cytoplasmic synthesis of the pregenome resulted in hepadnaviral dna synthesis. moreover, complete infectious virus was produced from cells transfected with hepadnaviral pregenomic rna. we conclude that the pregenome of hepadnaviruses can express all the proteins required ... | 1991 | 1895392 |
| the isolation and culture of dhbv-infected embryo and duckling hepatocytes and the effect of aflatoxin b1 or irradiation on these cells. | the preparation of primary cultures of control and dhbv-infected duck hepatocytes from embryos and young ducklings is described. cultures of both embryo and duckling hepatocytes secreted duck serum proteins. cultures of hepatocytes established from ducklings maintained initial morphology for up to 3 weeks in culture and also exhibited high levels of metabolism of aflatoxin b1. embryonic cell cultures rapidly lost ability to metabolise afb1 and became overgrown by spindle-shaped cells. both embry ... | 1991 | 1900699 |
| duck hepatitis b virus: a model to assess efficacy of disinfectants against hepadnavirus infectivity. | the efficacy of three proprietary glutaraldehyde disinfectants and their component bases was assessed using the duck hepatitis b virus (dhbv) model. inactivation of infectivity of undiluted serum containing 10(6.8) id50/ml dhbv was assessed after a mixture with an equal volume of disinfectant had stood at room temperature for 10 min. a dried spill of infectious serum was simulated using sterile filter paper disks, saturated with serum containing dhbv, dried and then exposed to test disinfectant ... | 1991 | 1904824 |
| electron microscopic studies on duck hepatitis b virus particles in hepatocytes and sequential changes in various patterns of infection. | to investigate the critical factors involved in the elimination of the duck hepatitis b virus (dhbv) in acute infection, the sequential changes in the number of dhbv particles in hepatocytes were studied electron microscopically in ducks experimentally infected by dhbv. twenty japanese white peking ducks were infected with dhbv on the day of hatching, and on the 7th day and 14th day after hatching. inoculation of dhbv on the day of hatching, and on the 7th and 14th day after hatching resulted in ... | 1991 | 1916154 |
| regulatory sequences of duck hepatitis b virus c gene transcription. | the regulatory elements involved in transcription of the c gene of duck hepatitis b virus (dhbv) were investigated. several dhbv dna fragments were assayed for c gene promoter, enhancer, and silencer activity by using a chloramphenicol acetyltransferase (cat) reporter gene and transfection of established liver and nonliver cell lines. a major transcript initiating at nucleotide positions 2532 and 2533 and three minor transcripts initiating at positions 2453/2454 and 2461 were identified in cells ... | 1991 | 1920612 |
| a percutaneous liver biopsy technique in ducks (anas platyrhynchos) experimentally infected with duck hepatitis b virus. | aylesbury ducks (anas platyrhynchos) chronically infected with the duck hepatitis b virus provide a useful model for studying hepadna-virus infection, replication and the effects of antiviral therapy. in these studies, it is necessary to have an effective method for obtaining repeat liver specimens for histological and molecular analyses. we have therefore developed a percutaneous liver biopsy technique which has a low rate of complications, can be performed at repeated intervals, and provides s ... | 1991 | 1921325 |
| characterization of infectious and defective cloned avian hepadnavirus genomes. | the infectivity in vivo, replication competence in vitro, and expression of viral genes of several molecularly cloned duck hepatitis b virus (dhbv) genomes were investigated. in addition, replication competence, core protein expression, and secretion of viral proteins were investigated for a grey heron hepatitis b virus genome. except two, all dhbv isolates tested induced a systemic infection in pekin ducks when injected as cloned viral dna into the liver. after transfection of chicken hepatoma ... | 1991 | 1926780 |
| decreased replication capacity of a duck hepatitis b virus mutant with altered distal pre-s region. | we have observed in a previous study that insertion, deletion and partial frameshift mutation in the distal pre-s region did not abolish replication capacity of the duck hepatitis b virus (dhbv) (li et al., 1989, j. virol. 63, 4965-4968). to compare further the relative replication capacity between the pre-s mutant and wild type virus, ducts were infected with either the wild type dhbv strain or a pre-s mutant (fs-17) characterized by a total change of nine consecutive amino acid codons in the d ... | 1991 | 1927049 |
| a teratoma in a duck infected congenitally with duck hepatitis b virus. | a teratoma was diagnosed in an 8-month-old pekin duck based on the presence of tissue derived from embryonic ectoderm, mesoderm, and endoderm in the neoplasm. the neoplasm was examined for the presence of duck hepatitis b virus, because the duck was congenitally infected with the virus, a member of the hepadnavirus family that is associated with hepatic neoplasms in hepadnavirus-infected mammals. persistent infection occurred in the liver, but no evidence of viral infection was found in the neop ... | 1991 | 1953589 |
| hepatic neoplasms in aflatoxin b1-treated, congenital duck hepatitis b virus-infected, and virus-free pekin ducks. | to assess the effects of the combination of persistent hepadnavirus infection and chemical carcinogen exposure, aflatoxin b1 (afb) was administered p.o. for 60 days to congenitally duck hepatitis b virus (dhbv)-infected and virus-free pekin ducks, starting at 3 days of age, during a 28-month study. hepatic neoplasia occurred only in afb-dosed ducks. hepatocellular carcinomas or biliary carcinomas occurred in 4 of 8 dhbv-infected and 3 of 4 dhbv-free ducks, and hepatocellular adenomas developed i ... | 1990 | 1972346 |
| recent advances in hepatitis b viruses and hepatocellular carcinoma. | the data reviewed at this meeting reinforce the notion that hbv may contribute to the development of liver cancer through a variety of mechanisms, including activation of oncogenes (c-myc and n-myc) by insertional mutagenesis, expression of viral proteins (x and pre-s2/s) that function as trans-activators and possibly oncoproteins, and introduction of chromosomal defects through enzymatically mediated integration into the host genome. not all of these mechanisms appear to be active in every tumo ... | 1990 | 1980825 |
| natural and experimental infection of wild mallard ducks with duck hepatitis b virus. | wild duck populations were investigated over a 4 year period for duck hepatitis b virus (dhbv) infection and liver disease. it appeared that dhbv is endemic in wild migratory mallards from france and the u.s.a., although neither hepatocellular carcinoma nor viral dna integration could be detected in liver samples examined. the follow up of natural infection indicated that wild mallards developed significantly higher serum titres to dhbv dna than pekin ducks. the results of experimental transmiss ... | 1991 | 1993878 |
| myristylation of a duck hepatitis b virus envelope protein is essential for infectivity but not for virus assembly. | in addition to the major surface (s) protein, the envelope of the duck hepatitis b virus (dhbv) contains a related presurface (pres) protein whose n-terminus bears a covalently attached myristate group. we have explored the functional significance of this modification by examining the replicative potential of a mutant viral genome whose myristylation signal has been inactivated. following transfection into permissive hepatoma cells, the mutant expresses an unmyristylated pres protein of normal s ... | 1991 | 1994583 |
| morphogenetic and regulatory effects of mutations in the envelope proteins of an avian hepadnavirus. | the envelope gene of the avian hepadnavirus, duck hepatitis b virus, was mutated in order to dissect the functions of the two major envelope proteins pre-s/s and s. both envelope proteins were found to be required for virus particle assembly and secretion. the placement of stop codons after each of the first three aug codons in the pre-s region allowed efficient translational initiation at downstream aug codons to produce novel n-terminally truncated pre-s/s proteins. these proteins could substi ... | 1991 | 1995945 |
| a domain of the hepadnavirus capsid protein is specifically required for dna maturation and virus assembly. | mutations introduced into the capsid gene of duck hepatitis b virus (dhbv) were tested for their effects on viral dna synthesis and assembly of enveloped viruses. four classes of mutant phenotypes were observed among a series of deletions of covering the 3' end of the capsid open reading frame. class i mutant capsids were able to support normal single-stranded and relaxed circular viral dna synthesis; class ii mutant capsids supported normal single-stranded dna synthesis but not relaxed circular ... | 1991 | 2016770 |
| chronic hepadnavirus infections. | | 1991 | 2020700 |
| mechanism, kinetics, and role of duck hepatitis b virus e-antigen expression in vivo. | no duck hepatitis b virus (dhbv) pre-c transcript has been identified so far, and neither the interrelationship of e-antigen (dhbeag) with the expression of other viral antigens or virus replication nor its function is known. in this study we identified in infected livers a minor transcript from which the precursor protein of dhbeag could be synthesized. mutation of the first aug on this transcript abolished expression of dhbeag. dhbv genomes containing this mutation were infectious in pekin duc ... | 1991 | 2024487 |
| inhibitory effects of selected antiviral compounds on human hepatitis b virus dna synthesis. | by using an assay system based on a human hepatoblastoma cell line (hb611) that continuously synthesizes hepatitis b virus dna, the following compounds were found to inhibit hepatitis b virus dna synthesis at concentrations that were significantly lower than their minimum cytotoxic concentrations: 9-(2-phosphonylmethoxyethyl)-2,6-diaminopurine (pmedap), (s)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine, 9-(phosphonylmethoxyethyl)adenine, 2',3'-dideoxy-2',3'-didehydrocytidine, and 2',3'-dideoxyc ... | 1991 | 2024975 |
| cis-acting sequences required for encapsidation of duck hepatitis b virus pregenomic rna. | hepadnavirus reverse transcription requires that pregenomic rna first be selectively packaged into a cytoplasmic core particle. this process presumably requires the presence of specific recognition sequences on the pregenomic rna. to define the cis-acting sequences required for pregenome encapsidation in the duck hepatitis b virus (dhbv), we assayed the packaging efficiency of a series of pregenomic rna deletion mutants and hybrid dhbv/lacz fusion transcripts. the 5' boundary of the packaging si ... | 1991 | 2033673 |
| biosynthesis of the secretory core protein of duck hepatitis b virus: intracellular transport, proteolytic processing, and membrane expression of the precore protein. | the biosynthesis of the secretory core gene product of the duck hepatitis b virus (dhbe protein) was examined. recombinant vaccinia viruses were constructed encoding either the full-length or c-terminally truncated forms of the dhbe precursor protein (precore protein) and used to express these proteins in the human hepatoma cell line hepg2. western immunoblot analysis of core gene products isolated from cells producing the full-length precore protein revealed the presence of dhbe precursor prote ... | 1991 | 2041077 |
| identification of a strong enhancer element upstream from the pregenomic rna start site of the duck hepatitis b virus genome. | the genome of the duck hepatitis b virus (dhbv) contains an enhancer element. this sequence, of 192 bp, is located in the 3'-terminal coding region of the dna polymerase gene (nucleotides 2159 to 2351), upstream from the pregenomic rna start site. this enhancer potentiates a marked increased activity from the heterologous thymidine kinase promoter in an orientation-independent manner and at a proximal, as well as a distal, location. the dhbv enhancer activates transcription in a relatively cell- ... | 1991 | 2041096 |
| duck hepatitis b virus infection of non-hepatocytes. | one hundred and seventeen ducklings, 42 inoculated with duck hepatitis b virus (dhbv) 2 days after hatching and 55 connatally infected, were studied over a 6-month period in parallel with 20 ducklings without dhbv infection. using immunohistochemical, in situ and blot hybridization analyses, the natural course of hepatic and extrahepatic infection was examined. dhbv infection started in the liver 2-4 days post-inoculation. there, dhbv was found not only in hepatocytes, but also in bile duct epit ... | 1991 | 2046495 |
| inhibition of duck hepatitis b virus infection by lysosomotropic agents. | the early phases of hepadnaviral infection were studied in primary duck hepatocyte cultures. incubation of duck hepatocytes in vitro with duck hepatitis b virus (dhbv) resulted in infection with high levels of viral replication. the lysosomotropic agents ammonium chloride and chloroquine effectively inhibited viral infection, indicating that dhbv infection, similar to infection with other enveloped viruses, depends on receptor-mediated endocytosis and involves membrane fusion triggered by low ph ... | 1991 | 2053292 |
| [ultrastructural study of duck hepatitis b virus in biliary epithelial cells of duck liver]. | liver specimens from shanghai ma ducks infected with duck hepatitis b virus (dhbv) were examined by immunohistochemical technique and electron microscopy. the results showed that dhbv and dhbv antigen were found not only in the hepatocytes but also in the biliary epithelial cells of infected ducks. electron microscopy also revealed that incomplete spherical particles, 40-50 nm in diameter, were present in the dilated cisternae of rough endoplasmic reticulum (rer), and complete spherical virions, ... | 1990 | 2081353 |
| effect of phyllanthus amarus on duck hepatitis b virus replication in vivo. | nine ducks congenitally infected with the duck hepatitis b virus (dhbv) were treated either orally (four ducks for 10 weeks) or intraperitoneally (five ducks for 12 weeks) with the indian traditional herbal remedy phyllanthus amarus. compared to placebo-treated control ducks, these treatments did not result in a reduction of circulating viral dna in the serum or in the level of viral dna replication in the liver. in two of the five intraperitoneal-treated ducks, a reduction in the levels of duck ... | 1990 | 2081970 |
| phosphonylmethoxyalkyl derivatives of purine as inhibitors of human hepatitis b virus dna synthesis. | a selected number of antiviral compounds which have been previously shown to inhibit the replication of dna viruses or retroviruses were examined for their inhibitory effects on human hepatitis b virus (hbv) dna synthesis. the assay system was based on the use of a human hepatoblastoma cell line (hb611) that continuously synthesizes hbv dna. the following phosphonylmethoxyalkyl-purine derivatives were found to inhibit hbv dna synthesis: 9-(2-phosphonyl-methoxyethyl)-2',6'-diaminopurine (pmedap), ... | 1990 | 2101900 |
| contribution of aflatoxin b1 and hepatitis b virus infection in the induction of liver tumors in ducks. | the study of two major risk factors in the development of hepatocellular carcinoma, namely persistent hepatitis virus infection and exposure to dietary aflatoxins, has been hampered by lack of an experimental system. to this end we have used a pekin duck model to examine the effect of congenital duck hepatitis b virus (dhbv) infection and aflatoxin b1 (afb1) exposure in the induction and development of liver cancer. afb1 was administered to dhbv infected or noninfected ducks at two doses (0.08 a ... | 1990 | 2107970 |
| ultrastructural study of hepatitis b virus in biliary epithelial cells of duck liver. | liver specimens from the shanghai ma ducks congenitally infected with duck hepatitis b virus (dhbv) were examined by immunohistochemical technique and electron microscopy. all the 12 serum dhbv positive ducks showed varying degrees of positive straining in hepatocytes. in 8 of the 12 ducks, dhbv antigen was discovered in the cytoplasm of biliary epithelial cells. conventional electron microscopy revealed two kinds of virus particles in the biliary epithelial cells: 1. the incomplete virus, 40-50 ... | 1990 | 2119956 |
| postexposure treatment of experimental dhbv infection: a new therapeutic strategy. | the therapeutic efficacy of antiviral agents for postexposure prophylaxis to hepadnavirus infection has been studied using acyclovir and foscarnet in the duck hepatitis b virus (dhbv) model. a total of 112 pekin-aylesbury ducks were inoculated with dhbv at 11 days post-hatch. three days later, groups of these birds were injected intraperitoneally twice daily for 10 days with acyclovir (25 mg/kg) or foscarnet (250 mg/kg) or phosphate-buffered saline. serum samples were taken before, during, and u ... | 1990 | 2142501 |
| synthesis of hepadnavirus particles that contain replication-defective duck hepatitis b virus genomes in cultured huh7 cells. | to evaluate the possibility of producing transducible replication-defective hepadnaviruses, cloned mutant duck hepatitis b virus genomes were tested both for virus antigen production and viral dna synthesis following transfection into the human hepatoma cell line huh7. deletion of a cis-acting 12-nucleotide sequence implicated in viral dna synthesis, direct repeat 1 (dr1), resulted in the loss of ability to synthesize both mature viral dna and infectious virus. the delta dr1 mutant, however, pro ... | 1990 | 2153230 |
| in hepatocytes infected with duck hepatitis b virus, the template for viral rna synthesis is amplified by an intracellular pathway. | during the productive phase of chronic hepadnaviral infections, virion dna synthesis occurs in the cytoplasm of the infected hepatocyte, but viral rna is synthesized in the nucleus, apparently from a covalently closed, circular (ccc) viral dna. j. tuttleman, c. pourcel, and j. summers (1986a, cell 47, 451-460) have shown that the intracellular levels of ccc dna can increase during initiation of infection of duck hepatocytes in vitro with duck hepatitis b virus and during long term culture of inf ... | 1990 | 2155510 |
| trans-complementation of the c gene of human and the p gene of woodchuck hepadnaviruses. | a 5 bp insertion was introduced into the bsteii site at nucleotide 2815 in dna of hepatitis b virus (hbv) and a mutant hbv genome was produced, which coded for envelope and core proteins, but not for dna polymerase, due to a frameshift. cultured hepatoma cells (hepg2) were simultaneously transfected with a plasmid harbouring a tandem dimer of the mutant hbv dna and another plasmid harbouring a tandem dimer of dna of woodchuck hepatitis virus or duck hepatitis b virus. the replication of mutant h ... | 1990 | 2157804 |
| reduced duck hepatitis b virus viraemia in ducklings coinfected with the immunodepressive reticuloendotheliosis virus. | coinfection of avian hosts by duck hepatitis b virus (dhbv) and reticuloendotheliosis virus (rev) was studied to assess the effect of immunodepression by rev on the replication of dhbv. one-day-old ducklings, domestic chickens, and turkey poults were inoculated either with dhbv or dhbv and rev and were bled and weighed at regular intervals. dhbv infection as manifested by viraemia and dhbv dna in liver was established only in ducklings. all chickens and turkeys were negative for dhbv dna in seru ... | 1990 | 2160513 |
| hepadnaviruses, their infections and hepatocellular carcinoma. | ten years ago hepatitis b virus (hbv) was thought to be a unique virus, not included in any known family of viruses. following the discovery of a number of hbv-like viruses that infect birds and mammals, the existence of a new family known as hepadnaviridae has been confirmed. hepadnaviruses are small hepatotropic viruses that have a characteristic partially double stranded genome, exhibit a narrow host range and replicate by reverse transcription. the family currently comprises six viruses of w ... | 1990 | 2178194 |
| comparative activities of several nucleoside analogs against duck hepatitis b virus in vitro. | duck hepatitis b virus (dhbv) replication in primary duck hepatocytes was monitored by examining the synthesis of both dhbv dna and dhbv core antigen. several nucleoside analogs which were previously shown to inhibit the replication of dna viruses (i.e., herpesviruses) and retroviruses were examined for their inhibitory effects on the synthesis of dhbv core antigen in primary duck hepatocytes. (s)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine [(s)-hpmpa], 9-(2-phosphonylmethoxyethyl)-2,6-diamin ... | 1990 | 2201250 |
| serological analysis of duck hepatitis b virus infection. | a radioimmunoassay was developed to detect duck hepatitis b virus surface antigen and antibody; viraemia (dhbv dna or dhbsag) was detected in all ducks inoculated within 3 weeks post-hatch, and persistent infection developed in 93% of birds in this group. in contrast, only 80% and 60% of ducks inoculated 4- and 6-weeks post-hatch respectively developed viraemia, and approximately 70% of the viraemic ducks became carriers. markers of viraemia were undetected in ducks inoculated 8 weeks post-hatch ... | 1990 | 2220071 |
| open reading frames on plus strand genome of duck hepatitis b virus. | hepadnaviruses have open reading frames of surface, core, polymerase and x protein on the minus strand of the genome. we analyzed a plus strand of duck hepatitis b virus (dhbv) for the presence of open reading frame with a computer program. we found one frame on the area that is complement to 3' end of polymerase gene and 5' end of precore gene. that open reading frame is conserved in three strains of dhbv, and the predicted protein is about 80 amino acids. | 1990 | 2227263 |
| a synthetic peptide elicits antibody reactive with the native duck hepatitis b virus pre-s protein. | synthetic peptides p37-49 and p63-79, derived from the pre-s region of duck hepatitis b virus (dhbv), have been synthesized. only p37-49 was reactive with rabbit anti-dhbs/pre-s antibodies by radioimmunoprecipitation. antiserum prepared against p37-47 reacted with a 35k polypeptide of native dhbs/pre-s by immunoblotting. it is concluded that p37-49 (mgqhpaksmdvrr) mimics one of the epitopes of the dhbv pre-s antigen. | 1990 | 2230741 |
| complete nucleotide sequence of a chinese duck hepatitis b virus. | | 1990 | 2235506 |
| complete nucleotide sequence of a german duck hepatitis b virus. | | 1990 | 2235507 |
| extrahepatic replication of duck hepatitis b virus: more than expected. | replication of duck hepatitis b virus in extrahepatic tissue such as pancreas, kidney and spleen has been well documented. to assess whether there is more widespread extrahepatic virus replication, we assayed brain, heart, lung, thymus, pancreas, kidney, spleen and intestine of 1- to 16-wk-old ducklings for the presence of duck hepatitis b virus dna and mrna by blotting and in situ methods. replicative intermediates and single-stranded duck hepatitis b virus dna and rna transcripts were detected ... | 1990 | 2295470 |
| molecular characterization of a new variant of hepatitis b virus in a persistently infected homosexual man. | based on the diversity of nucleotide sequences of cloned hepatitis b virus dna genomes, we have predicted possible replication of genetic variants of human hepatitis b virus. this prediction is exemplified by studies of a chronic carrier of hbsag/adw2, who lacked anti-hbc but carried exceedingly high levels of hepatitis b virus dna in serum. molecular characterization of a number of clones revealed a restriction map that deviated significantly from the typical pattern of the adw2 subtype, especi ... | 1990 | 2307406 |
| hepadnavirus envelope proteins regulate covalently closed circular dna amplification. | primary duck hepatocytes were infected with a mutant duck hepatitis b virus defective in envelope protein but competent for viral dna synthesis. cells infected by this mutant accumulated higher levels of viral covalently closed, circular dna (cccdna) than those infected by wild-type virus. the accumulation of high levels of cccdna was due to a failure of the mutant-infected cells to suppress de novo cccdna synthesis compared with suppression by cells infected by the wild type. the envelope-defec ... | 1990 | 2335817 |
| encapsidation of truncated human hepatitis b virus genomes through trans-complementation of the core protein and polymerase. | mutational analyses and complementation tests were used to analyze the strategy of packaging and of replication of human hepatitis b virus (hbv). by creating new restriction enzyme sites and by varying the genome length of hbv mutants, we identified that the mutated genomes could be encapsidated through trans-complementation of the polymerase and/or core protein. this study demonstrates that the polymerase of hbv, similar to that of duck hepatitis b virus (dhbv), is synthesized de novo instead o ... | 1990 | 2345959 |
| efficient duck hepatitis b virus production by an avian liver tumor cell line. | duck hepatitis b virus (dhbv) is produced in small amounts following transfection of human hepatoma or hepatoblastoma cell lines with cloned viral dna. in a search for better hosts for dhbv replication, two avian liver cell lines were investigated. one of these cell lines, lmh, produced 5 to 10 times more dna replicative intermediates and 10 to 20 times more infectious dhbv than did either of the two human cell lines, huh-7 and hep g2. utilization of cell lines in genetic analyses of virus repli ... | 1990 | 2352324 |
| antiviral strategies in chronic hepatitis b virus infection: i. establishment of an in vitro system using the duck hepatitis b virus model. | primary duck hepatocyte (pdh) cultures were established from ducklings congenitally infected with the duck hepatitis b virus (dhbv), plated onto feeder cell layers of irradiated human embryonic lung fibroblasts, and observed for 2 to 3 weeks. this system permitted the survival of the pdh in a differentiated form free of fibroblastic overgrowth for at least 3 weeks. the hepatocytes were shown to contain all the replicative dna intermediates found during dhbv replication as well as the dhbv struct ... | 1990 | 2388048 |
| [primary serologic investigation of hbv-like virus existence in domestic animals and fowls]. | using the reagent kits for detecting human hbv, primary serologic investigation was made in 6 kinds of domestic animals and fowls (total 673) by elisa, spot hybridization and immuno-electronmicroscopy. the results showed that some sera samples of pigs, rabbits, chicken and geese were hbsag, hbeag positive and positive for spot hybridization by using 3(2)p-hbv-dna probe, which suggested that hbv-like viruses might exist in those domestic animals and fowls. hbv-like virus particles were seen in on ... | 1990 | 2391101 |
| experimental in ovo transmission of duck hepatitis b virus. | inoculation of fertile pekin duck eggs with diluted serum containing dhbv into eggs incubated for 24 h and into the extra-embryonic cavities of 14-day-old embryos resulted in a high proportion of viraemic ducklings irrespective of the route of inoculation. long-term observation of som of the ducks established that the viraemia induced experimentally is long-lasting and has persisted for periods up to 16 mth post-hatch. separation of dhbv from the plasma of carrier ducks by rate zonal centrifugat ... | 1985 | 2409101 |
| evidence that a capped oligoribonucleotide is the primer for duck hepatitis b virus plus-strand dna synthesis. | the plus strand of virion dna of duck hepatitis b virus possessed, at its 5' terminus, a capped oligoribonucleotide 18 to 19 bases in length. this oligoribonucleotide had a unique 5' end, the heterogeneity in length reflecting two distinct junctions with plus-strand dna that were 1 base apart. the sequence of the rna differed from that predicted by the sequence of duck hepatitis b virus upstream of the 5' ends of plus-strand dna but was identical to a downstream sequence corresponding to the 5' ... | 1986 | 2416950 |
| appearance of viral rna transcripts in the early stage of duck hepatitis b virus infection. | sequential analysis of duck hepatitis b virus (dhbv) dna and rna transcripts in the liver of the early stage of infection was carried out using 1-day-old ducklings inoculated with dhbv-positive serum. using southern blot analysis, a band of supercoiled dhbv dna was detectable at 6 hr, when dhbv-specific poly[a]+rna was also observed by northern blot analysis as a faint smear below 3-kb. bands of rna at 3.5, 2.7, and 2.5 kb were detected at 12 hr, just before single-stranded viral dna was detecte ... | 1986 | 2425482 |
| characterization of a pre-s polypeptide on the surfaces of infectious avian hepadnavirus particles. | dna from the pre-s region of the duck hepatitis b virus (dhbv) genome was inserted into an open reading frame vector designed to give high-level expression in escherichia coli. the resulting fusion protein contained the first 8 amino acids of beta-galactosidase, 86 amino acids of the dhbv pre-s region, and 219 amino acids of chloramphenicol acetyltransferase at the c terminus (beta-gal:pre-s:cat). rabbit antiserum against purified beta-gal:pre-s:cat was used to identify pre-s-containing polypept ... | 1987 | 2437317 |
| in vivo study of the mechanism of action of antiviral agents against hepadna virus replication in the liver. resistance of supercoiled viral dna. | the mode of action of antiviral agents (interferon and adenine arabinoside) was studied in human and in animals chronically infected with hepadna virus. interferon (36-100 megaunits) was given to 20 carrier patients, and hepatitis b virus (hbv)-dna replicative forms were studied in pre- and post-treatment biopsies. ara-a was given intravenously to duck hepatitis b virus (dhbv)-infected ducks. changes in intrahepatic viral replicative forms were studied by southern blotting using 32p-labelled hbv ... | 1986 | 2439576 |
| duck hepatitis b virus: dna polymerase and reverse transcriptase activities of replicative complexes isolated from liver and their inhibition in vitro. | the duck hepatitis b virus (dhbv)-associated activities of reverse transcriptase and dna polymerase and their inhibition in vitro were studied. replicative complexes (rcs) were isolated from dhbv-infected liver by gel chromatography followed by sucrose gradient centrifugation. the rcs were detected by dot blot hybridization, using radiolabeled cloned dhbv dna as a probe, and by the incorporation of 32p-ttp in the presence of datp, dctp, dgtp, and mg2+ (endogenous dna polymerase activity). the en ... | 1988 | 2452518 |
| suramin inhibits in vitro infection by duck hepatitis b virus, rous sarcoma virus, and hepatitis delta virus. | suramin blocked in vitro infection by duck hepatitis b virus, a hepadnavirus, and rous sarcoma virus, a retrovirus. although suramin was able to inhibit the virus-encoded reverse transcriptase activities of these two viruses, this inhibition did not appear to account for the anti-viral effect of the drug. in particular, suramin was unable to block synthesis within cells of full-length viral dnas when added subsequent to infection. the results are consistent with the hypothesis that suramin acted ... | 1988 | 2462306 |
| synthesis and encapsidation of duck hepatitis b virus reverse transcriptase do not require formation of core-polymerase fusion proteins. | the expression strategy of the duck hepatitis b virus (dhbv) p gene, which is assumed to encode the viral reverse transcriptase, was investigated by mutational analysis. this study showed that p gene expression starts in the region where the p gene overlaps the viral core gene. however, in contrast to retroviral reverse transcriptases, which are expressed via gag-pol fusion protein intermediates, the dhbv p gene product was found to be synthesized starting at a p gene atg codon. the resulting pr ... | 1989 | 2463093 |
| epitope mapping of neutralizing monoclonal antibodies against duck hepatitis b virus. | in this article we report the first topological mapping of neutralizing epitopes of a hepadnavirus. duck hepatitis b virus is the only hepadnavirus that can replicate and spread from cell to cell in tissue culture. as a result, it is possible to study hepadnaviral neutralization in vitro with this system. to accomplish this goal, we produced a library of monoclonal antibodies against duck hepatitis b virus and identified 12 neutralizing monoclonal antibodies by using an in vitro neutralization a ... | 1989 | 2470915 |
| inhibition of duck hepatitis b virus replication by 2',3'-dideoxycytidine. a potent inhibitor of reverse transcriptase. | the effect of 2',3'-dideoxycytidine, a potent antiviral agent, which, following anabolic phosphorylation, inhibits the reverse transcriptase of the human immunodeficiency virus in vitro, was assessed in 16 pekin ducks chronically infected with the duck hepatitis b virus. nine ducks were given 11 mg/m2 of dideoxycytidine intravenously every 6 h, and 7 ducks received no treatment. serum duck hepatitis b virus deoxyribonucleic acid and deoxyribonucleic acid polymerase activity decreased in every du ... | 1989 | 2477299 |
| inhibition of rna- and dna-dependent duck hepatitis b virus dna polymerase activity by nucleoside and pyrophosphate analogs. | the dna polymerase of hepadnaviruses has two different functions during virus replication. it acts both as an rna-dependent dna polymerase (reverse transcriptase) and as a dna-dependent dna polymerase. duck hepatitis b virus (dhbv) preparations were used to investigate the inhibitory effects of selected compounds on these two enzyme activities. the reverse transcriptase activity was represented by an actinomycin d-resistant, phosphonoformate-sensitive dna polymerase activity isolated from dhbv-i ... | 1989 | 2483879 |
| [the interferon system in ducks infected with viral hepatitis b]. | the duck peripheral blood lymphocytes and spleen cells were shown to be relatively resistant to interferon induction by viral (ndv) and nonviral (dsrna) inducers as well as to con a induction of gamma-interferon. the concentration of the inducers had to be increased 4-5-fold to induce interferon production. charry valley ducks produced more alpha-interferon than peking ducks. the level of interferon production induced by ndv and dsrna (ridostin) was similar in dhbv-positive peking ducks and in t ... | 1989 | 2508328 |
| a sequential histologic and immunohistochemical study of duck hepatitis b virus infection in pekin ducks. | twenty-nine pekin ducks were inoculated with duck hepatitis b virus (dhbv), dhbv-free serum, or saline at 1 day of age. congenitally dhbv-infected ducks were also studied. ducks were killed periodically during a 92-week study and examined histologically and immunohistochemically to assess liver and extrahepatic inflammation and to detect and characterize dhbv core antigen tissue distribution. dhbv infection produced an asymptomatic but persistent dhbv viremia in all ducks associated with a mild ... | 1989 | 2540586 |