| analysis of integrated ground squirrel hepatitis virus and flanking host dna in two hepatocellular carcinomas. | we cloned the integrated ground squirrel hepatitis b virus (gshv) sequences from two hepatomas showing a single viral insertion. the gshv inserts shared structural features with integrated dnas of other hepadnaviruses. insertional activation of a cellular gene appears unlikely: the integrated gshv sequences lacked the known viral enhancers and were not expressed in the tumors, and we found no evidence for the presence of a gene at the integration site. our results, together with those earlier st ... | 1994 | 8035528 |
| functional analysis of ground squirrel hepatitis virus enhancer ii. | we have characterized a major regulatory element of ground squirrel hepatitis virus (gshv) located within a 90-nucleotide fragment of the core promoter upstream sequences and have compared its organization to that of woodchuck hepatitis virus (whv) enhancer ii (we2). the gshv element (ge2) stimulates transcription from the viral core promoter and heterologous promoters in an orientation-independent manner but displays a lower level of activity than we2 in transient transfection assays in human h ... | 1998 | 9445066 |
| full-genome sequence analyses of hepatitis b virus (hbv) strains recovered from chimpanzees infected in the wild: implications for an origin of hbv. | hepatitis b virus (hbv) belongs to the genus orthohepadnavirus of the family hepadnaviridae. having been found in various animals (duck, heron, woodchuck, ground squirrel, and primates), hepadnaviruses must have undergone a long history of evolution and may comprise more members than currently recognized. chimpanzees may also have their own hepadnavirus, even if it might be very close to hbv. we analyzed hbv-like sequences from three chimpanzees (pan troglodytes) that were most likely infected d ... | 2000 | 10648183 |
| universal primers for real-time amplification of dna from all known orthohepadnavirus species. | the family of hepadnaviridae is made up of members infecting birds (genus avihepadnavirus) or mammals (genus orthohepadnavirus). hepatitis b virus (hbv), the hepadnavirus infecting humans, can be divided into the seven genotypes a-g. by definition, genotypes differ by more than 8% at the nucleotide level. however, some genotypes differ by more than 14% from others. | 2003 | 12727526 |
| a new avian hepadnavirus infecting snow geese (anser caerulescens) produces a significant fraction of virions containing single-stranded dna. | we describe the identification and functional analysis of an evolutionary distinct new avian hepadnavirus. infection of snow geese (anser caerulescens) with a duck hepatitis b virus (dhbv)-related virus, designated sghbv, was demonstrated by detection of envelope proteins in sera with anti-dhbv pres and s antibodies. comparative sequence analysis of the pcr-amplified sghbv genomes revealed unique sghbv sequence features compared with other avian hepadnaviruses. unlike dhbv, sghbv shows an open r ... | 1999 | 10489339 |
| heterogeneous response for a mammalian hepadnavirus infection to acyclovir: drug-arrested intermediates of minus-strand viral dna synthesis are enveloped and secreted from infected cells as virion-like particles. | three woodchucks infected persistently with the woodchuck hepatitis virus (whv) were treated with acyclovir (acv) to investigate the effect of inhibiting viral dna synthesis upon the replication of an orthohepadnavirus in vivo. normal viraemia was reduced during the treatment period in all three animals, but each responded with a distinct serum phenotype. in the most provocative case, the profile of the whv dnas in both the liver and serum provided a simple and novel description of the orthohepa ... | 1997 | 8986943 |
| a new hepadnavirus endemic in arctic ground squirrels in alaska. | we present evidence for a novel member of the hepadnavirus family that is endemic in wild arctic ground squirrels (spermophylus parryi kennicotti) in alaska. this virus, designated arctic squirrel hepatitis virus (ashv), was initially detected in the livers of animals bearing large hepatic nodules by nucleic acid hybridization with hepadnavirus probes and in plasma by cross-reactivity with antibodies to hepadnavirus surface and core antigens. the complete nucleotide sequence of the 3,302-bp-long ... | 1996 | 8676441 |
| sequences regulating poly(a) site selection within the adenovirus major late transcription unit influence the interaction of constitutive processing factors with the pre-mrna. | the adenovirus major late transcription unit (mltu) encodes five families of mrnas, l1 to l5, each distinguished by a unique poly(a) site. use of the promoter-proximal l1 poly(a) site predominates during early infection, whereas poly(a) site choice shifts to the promoter-distal sites during late infection. a mini-mltu containing only the l1 and l3 poly(a) sites has been shown to reproduce this processing switch. in vivo analysis has revealed that sequences extending 5' and 3' of the l1 core poly ... | 1996 | 8627700 |
| state of the p53 gene in hepatocellular carcinomas of ground squirrels and woodchucks with past and ongoing infection with hepadnaviruses. | infection with hepadnaviruses and exposure to dietary aflatoxin are considered major risk factors in the development of hepatocellular carcinoma (hcc) both in humans and in animals. recently, a broad range of mutations in the p53 tumor suppressor gene has been reported in human hccs, predominantly from hepatitis b virus carriers in areas with either high or low levels of exposure to dietary aflatoxin. to determine whether p53 mutations are common to hccs of hosts infected with related hepadnavir ... | 1994 | 7923176 |
| phenotypic mixing between different hepadnavirus nucleocapsid proteins reveals c protein dimerization to be cis preferential. | hepadnaviruses encode a single core (c) protein which assembles into a nucleocapsid containing the polymerase (p) protein and pregenomic rna during viral replication in hepatocytes. we examined the ability of heterologous hepadnavirus c proteins to cross-oligomerize. using a two-hybrid assay in hepg2 cells, we observed cross-oligomerization among the core proteins from hepatitis b virus (hbv), woodchuck hepatitis virus, and ground squirrel hepatitis virus. when expressed in xenopus oocytes, in w ... | 1994 | 7518533 |
| protein x of hepatitis b virus: origin and structure similarity with the central domain of dna glycosylase. | orthohepadnavirus (mammalian hosts) and avihepadnavirus (avian hosts) constitute the family of hepadnaviridae and differ by their capability and inability for expression of protein x, respectively. origin and functions of x are unclear. the evolutionary analysis at issue of x indicates that present strains of orthohepadnavirus started to diverge about 25,000 years ago, simultaneously with the onset of avihepadnavirus diversification. these evolutionary events were preceded by a much longer perio ... | 2011 | 21850270 |
| management of viral infections in solid organ transplant recipients. | management of viral infections after transplantation involves antiviral drug therapy (if available) and reduction in immunosuppression, which allows for development of pathogen-specific immunity to the offending virus. prevention of viral infections is of the utmost importance, and this may be accomplished through vaccination, antiviral strategies and infection control measures. this article discusses the current management of selected viral pathogens that cause clinical illness in solid organ t ... | 2011 | 21692673 |
| exposure to risk factors for hepatitis b and c viruses among primary school teachers in karachi. | the study aimed to determine hepatitis b vaccination status and assess the exposure of risk factors for hepatitis b and c among primary schoolteachers in karachi, pakistan. | 2010 | 21045353 |
| seroprevalence of hiv, hbv, hcv and syphilis in blood donors in southern haryana. | blood transfusion is an important mode of transmission of infections to recipients. the aim of the study was to assess the prevalence of transfusion-transmissible infections among blood donors. for this, a 3.5-year retrospective study, from october 2002 to april 2006 was conducted at the blood transfusion centre of maharaja agrasen medical college, agroha (hisar) haryana. donors were screened for seroprevalence of hiv, hbv, hcv and syphilis. a total of 5849 donors were tested, out of which 4010 ... | 2010 | 20551540 |
| prevalence of a virus similar to human hepatitis b virus in swine. | the objective of this study is to established evidence of the existence of a novel member of the hepadnavirus family endemic in swine. temporarily this virus was designated as swine hepatitis b virus (shbv). this shbv can be detected by using human hepatitis b virus diagnostic kits including elisa, immunohistochemical staining, and transmission electron microscopy (tem). also seroprevalence of pig farms in beijing, china, and pathological features of shbv infection was determined. | 2010 | 20233455 |
| bioinformatic analysis of the hepadnavirus e-antigen and its precursor identifies remarkable sequence conservation in all orthohepadnaviruses. | the hepatitis b e-antigen (hbeag) is a non-particulate secretory protein expressed by all viruses within the family hepadnaviridae. it is not essential for viral assembly or replication but is important for establishment of persistent infection in vivo. although the exact mechanism(s) by which the hbeag manifests chronicity are unclear, the hbeag elicits both humoral and cell-mediated immunity, down-regulates the innate immune response to infection, as well as functioning as a t cell tolerogen a ... | 2010 | 19950245 |
| acute hepatitis e virus infection in taiwan 2002-2006 revisited: pcr shows frequent co-infection with multiple hepatitis viruses. | sporadic cases of acute hepatitis e virus (hev) infection with production of anti-hev igm have been reported occasionally in taiwan despite no reported outbreaks in the past. this study was undertaken to determine whether serological markers correlated with virus detection. from 2002 to 2006, 72 reported cases of acute hepatitis e seropositive for anti-hev igm in taiwan were enrolled for investigation. acute phase serum samples were collected for detection of hev rna, hbv dna, hcv rna, and gbv-c ... | 2009 | 19697413 |
| a novel mouse model for immunogenic evaluation of human hbv vaccines. | to prepare a human hbv vaccine, investigators need an animal model that can help them screen and prioritize vaccine candidates. in this study, hbv/hla-a2.1 double transgenic mice (dtg), confirmed by analysis of genomic integration and by observation of long-term expression of hbv and hla genes, were generated for the first time. the hbv/hla-a2.1 dtg not only display tolerance to hbv antigens (ags), but also have the ability to process and present hla-a2 restricted antigenic epitopes. the animals ... | 2009 | 19615480 |
| performance evaluation of the qiagen ez1 dsp virus kit with abbott realtime hiv-1, hbv and hcv assays. | automated sample preparation systems must meet the demands of routine diagnostics laboratories with regard to performance characteristics and compatibility with downstream assays. | 2009 | 19286419 |
| liver cirrhosis in hiv-infected patients: prevalence, aetiology and clinical outcome. | liver disease is frequently seen in hiv+ patients as a result of coinfection with hepatitis b (hbv) or c (hcv) viruses, alcohol abuse and/or exposure to hepatotoxic drugs. the aim of this study was to assess the prevalence of liver cirrhosis, its main causes and clinical presentation in hiv+ patients. observational, cross-sectional, retrospective study of all hiv+ individuals followed at one reference hiv outpatient clinic in madrid. liver fibrosis was measured in all cases using transient elast ... | 2008 | 18233989 |
| identification of interspecies recombination among hepadnaviruses infecting cross-species hosts. | members of the family hepadnaviridae are divided into two genera, orthohepadnavirus (from mammalian) and avihepadnavirus (from avian). recombination had been found to occur among human hepatitis b virus (hbv) strains of different genotypes, or between hepadnavirus strains from human and nonhuman primate. to reach a comparatively complete inspection of interspecies recombination events among hepadnavirus strains from various hosts, 837 hepadnavirus complete genome sequences from human and 112 fro ... | 2007 | 17854046 |
| hepatitis b virus taxonomy and hepatitis b virus genotypes. | hepatitis b virus (hbv) is a member of the hepadnavirus family. hepadnaviruses can be found in both mammals (orthohepadnaviruses) and birds (avihepadnaviruses). the genetic variability of hbv is very high. there are eight genotypes of hbv and three clades of hbv isolates from apes that appear to be additional genotypes of hbv. most genotypes are now divided into subgenotypes with distinct virological and epidemiological properties. in addition, recombination among hbv genotypes increases the var ... | 2007 | 17206751 |
| viral and cellular determinants involved in hepadnaviral entry. | hepadnaviridae is a family of hepatotropic dna viruses that is divided into the genera orthohepadnavirus of mammals and avihepadnavirus of birds. all members of this family can cause acute and chronic hepatic infection, which in the case of human hepatitis b virus (hbv) constitutes a major global health problem. although our knowledge about the molecular biology of these highly liver-specific viruses has profoundly increased in the last two decades, the mechanisms of attachment and productive en ... | 2007 | 17206752 |
| avian and mammalian hepadnaviruses have distinct transcription factor requirements for viral replication. | hepadnavirus replication occurs in hepatocytes in vivo and in hepatoma cell lines in cell culture. hepatitis b virus (hbv) replication can occur in nonhepatoma cells when pregenomic rna synthesis from viral dna is activated by the expression of the nuclear hormone receptors hepatocyte nuclear factor 4 (hnf4) and the retinoid x receptor alpha (rxr alpha) plus peroxisome proliferator-activated receptor alpha (ppar alpha) heterodimer. nuclear hormone receptor-dependent hbv replication is inhibited ... | 2002 | 12097559 |
| a short n-proximal region in the large envelope protein harbors a determinant that contributes to the species specificity of human hepatitis b virus. | infection by hepatitis b virus (hbv) is mainly restricted to humans. this species specificity is likely determined at the early phase of the viral life cycle. since the envelope proteins are the first viral factors to interact with the cell, they represent attractive candidates for controlling the hbv host range. to investigate this assumption, we took advantage of the recent discovery of a second virus belonging to the primate orthohepadnavirus genus, the woolly monkey hbv (wmhbv). a recombinan ... | 2001 | 11689638 |
| hepatitis a vaccination in chronic liver disease: is it really required in a tropical country like india? | vaccination against hepatitis a virus (hav) has been recommended in patients with chronic liver disease to prevent any decompensation due to superinfection. this may not hold good in high endemic areas for hepatitis a like india. the aim of this study was to find out the seroprevalence of anti-hav antibodies in patients with chronic liver disease and to justify the need for vaccination against hepatitis a virus in these patients. one hundred and thirty three consecutive patients with cirrhosis o ... | 2007 | 17582184 |
| hepatitis b immunoglobulin and lamivudine improve hepatitis b-related outcomes after liver transplantation: meta-analysis. | hbv recurrence increases morbidity and mortality in hbsag+ patients undergoing liver transplantation. we aimed to estimate the relative efficacy of combined therapy with hepatitis b immunoglobulin (hbig) and lamivudine (lam) versus hbig monotherapy for preventing hbv-related morbidity and mortality in this setting. | 2008 | 18456569 |
| hepatitis b virus x protein (hbx) activates atf6 and ire1-xbp1 pathways of unfolded protein response. | numerous viruses including hepatitis b virus (hbv) induce endoplasmic reticulum (er) stress, which interrupts protein folding causing accumulation of unfolded or misfolded proteins in er. to alleviate the stress placed on er, these proteins must be refolded or degraded by activating a specific cellular response known as er stress response or unfolded protein response (upr). two upr-specific signaling pathways involving transmembrane proteins atf6 and xbp1 generate critical transcription factors ... | 2007 | 17092596 |