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1.
Viruses ; 15(10)2023 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-37896884

RESUMO

Cutaneous plantar papillomas are a relatively common lesion of wild psittacine birds in Australia. Next-generation sequencing technology was used to investigate the potential aetiologic agent(s) for a plantar cutaneous papilloma in a wild rainbow lorikeet (Trichoglosis moluccanus). In the DNA from this lesion, two novel viral sequences were detected. The first was the partial sequence of a herpesvirus with the proposed name, psittacid alphaherpesvirus 6, from the Mardivirus genus of the family alphaherpesviruses. This represents the first mardivirus to be detected in a psittacine bird, the first mardivirus to be detected in a wild bird in Australia, and the second mardivirus to be found in a biopsy of an avian cutaneous papilloma. The second virus sequence was a complete sequence of a hepadnavirus, proposed as parrot hepatitis B genotype H (PHBV-H). PHBV-H is the first hepadnavirus to be detected in a wild psittacine bird in Australia. Whether other similar viruses are circulating in wild birds in Australia and whether either of these viruses play a role in the development of the plantar papilloma will require testing of biopsies from similar lesions and normal skin from other wild psittacine birds.


Assuntos
Alphaherpesvirinae , Avihepadnavirus , Doenças das Aves , Herpesviridae , Papiloma , Papagaios , Animais , Herpesviridae/genética , Vírus Oncogênicos , Papiloma/veterinária , Poliésteres
2.
Arch Virol ; 168(3): 85, 2023 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-36763177

RESUMO

Research into disease pathogens can greatly benefit from viral metagenomics technology. Using this technique, we investigated potential disease pathogens that resulted in the death of many ducks on a duck farm. Two duck circoviruses (DuCV) and one duck hepatitis B virus (DHBV) were detected and identified, and all three strains were closely related to avian-associated viruses. Two duck circoviruses had 81.64%-97.65% genome-wide sequence identity to some reference strains, and duck hepatitis B virus shared 75.85%-98.92% identity with other strains. Clinical characteristics of the diseased ducks, including ruffled feathers, lethargy, and weight loss, were comparable to those observed in cases of DuCV infection. Further research is needed to determine whether coinfection with DHBV leads to liver damage and exacerbation of the disease.


Assuntos
Avihepadnavirus , Vírus da Hepatite B do Pato , Hepatite Viral Animal , Animais , Patos , Fazendas , DNA Viral , Vírus da Hepatite B do Pato/genética , Fígado
3.
Virology ; 438(2): 98-105, 2013 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-23411008

RESUMO

Avihepadnaviruses have previously been isolated from various species of duck, goose, stork, heron and crane. Recently the first parrot avihepadnavirus was isolated from a Ring-necked Parakeet in Poland. In this study, 41 psittacine liver samples archived in Poland over the last nine years were tested for presence of Parrot hepatitis B virus (PHBV). We cloned and sequenced PHBV isolates from 18 birds including a Crimson Rosella, an African grey parrot and sixteen Ring-necked Parakeets. PHBV isolates display a degree of diversity (>78% genome wide pairwise identity) that is comparable to that found amongst all other avihepadnaviruses (>79% genome wide pairwise identity). The PHBV viruses can be subdivided into seven genetically distinct groups (tentatively named A-G) of which the two isolated of PHBV-G are the most divergent sharing ∼79% genome wide pairwise identity with all their PHBVs. All PHBV isolates display classical avihepadnavirus genome architecture.


Assuntos
Avihepadnavirus/classificação , Avihepadnavirus/genética , Doenças das Aves/virologia , DNA Viral/genética , Variação Genética , Infecções por Hepadnaviridae/veterinária , Papagaios/virologia , Animais , Avihepadnavirus/isolamento & purificação , Sequência de Bases , Clonagem Molecular , Genoma Viral , Infecções por Hepadnaviridae/virologia , Periquitos/virologia , Filogenia , Análise de Sequência de DNA
4.
Arch Virol ; 157(3): 585-90, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22183110

RESUMO

Avihepadnaviruses have been documented previously in ducks, herons, geese, storks and cranes. Here, we describe the full genome of a new avihepadnavirus isolated from Psittacula krameri (ring-necked parrot) in Poland. The parrot hepatitis B virus (PHBV) genome (3042 bp) shares <76% sequence identity with other avihepadnavirus isolates and is phylogenetically most closely related to heron and stork hepatitis B viruses isolates. PHBV has a genome organization similar to that of other hepadnaviruses and contains ORFs for a preC/C, preS/S and polyprotein. Additionally, we identified an X-like ORF in the genome of PHBV. The full-genome data will be useful in developing screening tools for avihepadnaviruses in parrots.


Assuntos
Avihepadnavirus/genética , Avihepadnavirus/isolamento & purificação , DNA Viral/genética , Genoma Viral , Psittacula/virologia , Análise de Sequência de DNA , Animais , Análise por Conglomerados , Dados de Sequência Molecular , Fases de Leitura Aberta , Filogenia , Polônia
5.
PLoS One ; 6(8): e23392, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21850270

RESUMO

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 period during which orthohepadnavirus developed a functional protein X while avihepadnavirus evolved without X. An in silico generated 3D-model of orthohepadnaviral X protein displayed considerable similarity to the tertiary structure of DNA glycosylases (key enzymes of base excision DNA repair pathways). Similarity is confined to the central domain of MUG proteins with the typical DNA-binding facilities but without the capability of DNA glycosylase enzymatic activity. The hypothetical translation product of a vestigial X reading frame in the genome of duck hepadnavirus could also been folded into a DNA glycosylase-like 3D-structure. In conclusion, the most recent common ancestor of ortho- and avihepadnavirus carried an X sequence with orthology to the central domain of DNA glycosylase.


Assuntos
DNA Glicosilases/química , DNA Glicosilases/metabolismo , Transativadores/química , Transativadores/metabolismo , Animais , Avihepadnavirus/enzimologia , DNA Glicosilases/genética , Humanos , Orthohepadnavirus/enzimologia , Estrutura Secundária de Proteína , Transativadores/genética , Proteínas Virais Reguladoras e Acessórias
6.
PLoS Pathog ; 4(12): e1000230, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19057662

RESUMO

Hepadnaviruses, including hepatitis B virus (HBV), a highly relevant human pathogen, are small enveloped DNA viruses that replicate via reverse transcription. All hepadnaviruses display a narrow tissue and host tropism. For HBV, this restricts efficient experimental in vivo infection to chimpanzees. While the cellular factors mediating infection are largely unknown, the large viral envelope protein (L) plays a pivotal role for infectivity. Furthermore, certain segments of the PreS domain of L from duck HBV (DHBV) enhanced infectivity for cultured duck hepatocytes of pseudotyped heron HBV (HHBV), a virus unable to infect ducks in vivo. This implied a crucial role for the PreS sequence from amino acid 22 to 90 in the duck tropism of DHBV. Reasoning that reciprocal replacements would reduce infectivity for ducks, we generated spreading-competent chimeric DHBVs with L proteins in which segments 22-90 (Du-He4) or its subsegments 22-37 and 37-90 (Du-He2, Du-He3) are derived from HHBV. Infectivity for duck hepatocytes of Du-He4 and Du-He3, though not Du-He2, was indeed clearly reduced compared to wild-type DHBV. Surprisingly, however, in ducks even Du-He4 caused high-titered, persistent, horizontally and vertically transmissable infections, with kinetics of viral spread similar to those of DHBV when inoculated at doses of 10(8) viral genome equivalents (vge) per animal. Low-dose infections down to 300 vge per duck did not reveal a significant reduction in specific infectivity of the chimera. Hence, sequence alterations in PreS that limited infectivity in vitro did not do so in vivo. These data reveal a much more complex correlation between PreS sequence and host specificity than might have been anticipated; more generally, they question the value of cultured hepatocytes for reliably predicting in vivo infectivity of avian and, by inference, mammalian hepadnaviruses, with potential implications for the risk assessment of vaccine and drug resistant HBV variants.


Assuntos
Avihepadnavirus/genética , Patos/virologia , Vírus da Hepatite B do Pato/genética , Vírus da Hepatite B do Pato/patogenicidade , Hepatite Viral Animal/virologia , Hepatócitos/virologia , Animais , Anseriformes/virologia , Avihepadnavirus/patogenicidade , Células Cultivadas , Quimera , Infecções por Hepadnaviridae/transmissão , Infecções por Hepadnaviridae/virologia , Hepatite Viral Animal/transmissão , Recombinação Genética , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/fisiologia , Vírion/patogenicidade
7.
J Med Virol ; 79(11): 1741-50, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17854046

RESUMO

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 from animals were analyzed by using fragment typing to scan for potential interspecies recombinants. Further bootscanning and phylogenetic analyses of the potential recombinants revealed six genome sequences as interspecies recombinants. Interspecies recombination events were found to occur among HBV strains from human and nonhuman primates, from gibbons of different genera, from chimpanzee and an unknown host, and between two avian hepadnavirus strains from birds of different subfamilies, which was identified for the first time. HBV interspecies recombinants were found to have recombination hot spots similar to that of human HBV intergenotype recombinants, breakpoints frequently locating near gene boundaries. Interspecies recombination found in this study may alter current views on hepadnavirus host specificity.


Assuntos
Hepadnaviridae/classificação , Hepadnaviridae/genética , Hepatite Viral Animal/virologia , Hepatite Viral Humana/virologia , Recombinação Genética , Animais , Avihepadnavirus/classificação , Avihepadnavirus/genética , Genoma Viral , Genótipo , Hepadnaviridae/isolamento & purificação , Humanos , Dados de Sequência Molecular , Orthohepadnavirus/classificação , Orthohepadnavirus/genética , Filogenia , Análise de Sequência de DNA , Especificidade da Espécie
8.
J Virol ; 81(23): 13230-4, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17881436

RESUMO

The icosahedral capsid of duck hepatitis B virus (DHBV) is formed by a single core protein species (DHBc). DHBc is much larger than HBc from human HBV, and no high-resolution structure is available. In an accompanying study (M. Nassal, I. Leifer, I. Wingert, K. Dallmeier, S. Prinz, and J. Vorreiter, J. Virol. 81:13218-13229, 2007), we used extensive mutagenesis to derive a structural model for DHBc. For independent validation, we here mapped the epitopes of seven anti-DHBc monoclonal antibodies. Using numerous recombinant DHBc proteins and authentic nucleocapsids from different avihepadnaviruses as test antigens, plus a panel of complementary assays, particle-specific and exposed plus buried linear epitopes were revealed. These data fully support key features of the model.


Assuntos
Avihepadnavirus/química , Vírus da Hepatite B do Pato/química , Nucleocapsídeo/química , Proteínas do Core Viral/química , Anticorpos Monoclonais/metabolismo , Anticorpos Antivirais/metabolismo , Avihepadnavirus/imunologia , Mapeamento de Epitopos , Epitopos/imunologia , Vírus da Hepatite B do Pato/imunologia , Modelos Moleculares , Nucleocapsídeo/imunologia , Estrutura Terciária de Proteína , Proteínas do Core Viral/imunologia
9.
Nucleic Acids Res ; 35(8): 2800-11, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17430968

RESUMO

Hepatitis B virus (HBV) replication is initiated by binding of its reverse transcriptase (P) to the apical stem-loop (AL) and primer loop (PL) of epsilon, a highly conserved RNA element at the 5'-end of the RNA pregenome. Mutation studies on duck/heron and human in vitro systems have shown similarities but also differences between their P-epsilon interaction. Here, NMR and UV thermodynamic data on AL (and PL) from these three species are presented. The stabilities of the duck and heron ALs were found to be similar, and much lower than that of human. NMR data show that this low stability stems from an 11-nt internal bulge destabilizing the stem of heron AL. In duck, although structured at low temperature, this region also forms a weak point as its imino resonances broaden to disappearance between 30 and 35 degrees C well below the overall AL melting temperature. Surprisingly, the duck- and heron ALs were both found to be capped by a stable well-structured UGUU tetraloop. All avian ALs are expected to adhere to this because of their conserved sequence. Duck PL is stable and structured and, in view of sequence similarities, the same is expected for heron - and human PL.


Assuntos
Avihepadnavirus/genética , Vírus da Hepatite B do Pato/genética , Vírus da Hepatite B/genética , RNA Viral/química , Termodinâmica , Sequência de Bases , Capsídeo/química , Dados de Sequência Molecular , Ressonância Magnética Nuclear Biomolecular
10.
World J Gastroenterol ; 13(1): 14-21, 2007 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-17206751

RESUMO

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 variability of HBV. This review summarises current knowledge of the epidemiology of genetic variability in hepadnaviruses and, due to rapid progress in the field, updates several recent reviews on HBV genotypes and subgenotypes.


Assuntos
Vírus da Hepatite B/classificação , Vírus da Hepatite B/genética , Filogenia , Animais , Avihepadnavirus/classificação , Avihepadnavirus/genética , DNA Recombinante/genética , DNA Viral/genética , Genótipo , Hepatite B/epidemiologia , Vírus da Hepatite B/isolamento & purificação , Humanos , Orthohepadnavirus/classificação , Orthohepadnavirus/genética , Prevalência
11.
World J Gastroenterol ; 13(1): 91-103, 2007 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-17206758

RESUMO

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.


Assuntos
Avihepadnavirus/genética , Avihepadnavirus/fisiologia , Infecções por Hepadnaviridae/patologia , Sequência de Aminoácidos , Animais , Avihepadnavirus/crescimento & desenvolvimento , Avihepadnavirus/patogenicidade , DNA Viral/genética , Modelos Animais de Doenças , Patos , Infecções por Hepadnaviridae/tratamento farmacológico , Infecções por Hepadnaviridae/fisiopatologia , Vírus da Hepatite B do Pato/genética , Vírus da Hepatite B do Pato/crescimento & desenvolvimento , Vírus da Hepatite B do Pato/patogenicidade , Vírus da Hepatite B do Pato/fisiologia , Dados de Sequência Molecular , Morfogênese/fisiologia , Tropismo/fisiologia , Proteínas Virais/análise , Proteínas Virais/fisiologia , Vacinas Virais/genética , Vacinas Virais/uso terapêutico , Internalização do Vírus , Replicação Viral/fisiologia
12.
J Gen Virol ; 86(Pt 5): 1335-1342, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15831944

RESUMO

Heron hepatitis B viruses (HHBVs) in three subspecies of free-living great blue herons (Ardea herodias) from Florida, USA, were identified and characterized. Eight of 13 samples were positive in all assays used, whereas sera from egrets, which are also members of the family Ardeidae, were negative in the same assays. Comparative phylogenetic analysis of viral DNA sequences from the preS/S region of previously reported and novel HHBV strains isolated from captive grey herons (Germany) and free-ranging great blue herons (USA), respectively, revealed a strong conservation (95 % sequence similarity) with two separate clusters, implying a common ancestor of all strains. Our data demonstrate for the first time that different subspecies of herons are infected by HHBV and that these infections exist in non-captive birds. Phylogenetic analysis and the fact that the different heron species are geographically isolated populations suggest that lateral transmission, virus adaptation and environmental factors all play a role in HHBV spreading and evolution.


Assuntos
Avihepadnavirus , Avihepadnavirus/isolamento & purificação , Doenças das Aves/transmissão , Aves/virologia , Infecções por Hepadnaviridae/veterinária , Animais , Avihepadnavirus/genética , Sequência de Bases , Doenças das Aves/virologia , DNA Viral/química , DNA Viral/isolamento & purificação , Transmissão de Doença Infecciosa , Infecções por Hepadnaviridae/transmissão , Infecções por Hepadnaviridae/virologia , Dados de Sequência Molecular , Filogenia , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência , Proteínas do Envelope Viral/genética
13.
J Virol ; 79(5): 2729-42, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15708992

RESUMO

Five new hepadnaviruses were cloned from exotic ducks and geese, including the Chiloe wigeon, mandarin duck, puna teal, Orinoco sheldgoose, and ashy-headed sheldgoose. Sequence comparisons revealed that all but the mandarin duck viruses were closely related to existing isolates of duck hepatitis B virus (DHBV), while mandarin duck virus clones were closely related to Ross goose hepatitis B virus. Nonetheless, the S protein, core protein, and functional domains of the Pol protein were highly conserved in all of the new isolates. The Chiloe wigeon and puna teal hepatitis B viruses, the two new isolates most closely related to DHBV, also lacked an AUG start codon at the beginning of their X open reading frame (ORF). But as previously reported for the heron, Ross goose, and stork hepatitis B viruses, an AUG codon was found near the beginning of the X ORF of the mandarin duck, Orinoco, and ashy-headed sheldgoose viruses. In all of the new isolates, the X ORF ended with a stop codon at the same position. All of the cloned viruses replicated when transfected into the LMH line of chicken hepatoma cells. Significant differences between the new isolates and between these and previously reported isolates were detected in the pre-S domain of the viral envelope protein, which is believed to determine viral host range. Despite this, all of the new isolates were infectious for primary cultures of Pekin duck hepatocytes, and infectivity in young Pekin ducks was demonstrated for all but the ashy-headed sheldgoose isolate.


Assuntos
Anseriformes/virologia , Avihepadnavirus/isolamento & purificação , Sequência de Aminoácidos , Animais , Animais Domésticos/virologia , Avihepadnavirus/classificação , Avihepadnavirus/genética , Avihepadnavirus/fisiologia , Sequência de Bases , Linhagem Celular , Galinhas , DNA Viral/genética , Patos/virologia , Feminino , Gansos/virologia , Hibridização In Situ , Masculino , Dados de Sequência Molecular , Filogenia , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Especificidade da Espécie , Proteínas Virais/genética , Virulência , Replicação Viral
14.
J Virol ; 78(16): 8780-7, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15280486

RESUMO

Packaging of hepadnavirus pregenomic RNA (pgRNA) into capsids, or encapsidation, requires several viral components. The viral polymerase (P) and the capsid subunit (C) are necessary for pgRNA encapsidation. Previous studies of duck hepatitis B virus (DHBV) indicated that two cis-acting sequences on pgRNA are required for encapsidation: epsilon, which is near the 5' end of pgRNA, and region II, located near the middle of pgRNA. Later studies suggested that the intervening sequence between these two elements may also make a contribution. It has been demonstrated for DHBV that epsilon interacts with P to facilitate encapsidation, but it is not known how other cis-acting sequences contribute to encapsidation. We analyzed chimeras of DHBV and a related virus, heron hepatitis B virus (HHBV), to gain insight into the interactions between the various viral components during pgRNA encapsidation. We learned that having epsilon and P derived from the same virus was not sufficient for high levels of encapsidation, implying that other viral interactions contribute to encapsidation. Chimeric analysis showed that a large sequence containing region II may interact with P and/or C for efficient encapsidation. Further analysis demonstrated that possibly an RNA-RNA interaction between the intervening sequence and region II facilitates pgRNA encapsidation. Together, these results identify functional interactions among various viral components that contribute to pgRNA encapsidation.


Assuntos
Avihepadnavirus/genética , Capsídeo/metabolismo , Produtos do Gene pol/metabolismo , Precursores de RNA/metabolismo , Recombinação Genética , Proteínas Virais/metabolismo , Animais , Avihepadnavirus/metabolismo , Linhagem Celular Tumoral , Galinhas , Elementos Facilitadores Genéticos , Vírus da Hepatite B do Pato/genética , Vírus da Hepatite B do Pato/metabolismo , Proteínas Virais/genética , Montagem de Vírus
15.
J Virol ; 76(18): 9087-95, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12186892

RESUMO

Previous analysis of duck hepatitis B virus (DHBV) indicated the presence of at least two cis-acting sequences required for efficient encapsidation of its pregenomic RNA (pgRNA), epsilon and region II. epsilon, an RNA stem-loop near the 5' end of the pgRNA, has been characterized in detail, while region II, located in the middle of the pgRNA, is not as well defined. Our initial aim was to identify the sequence important for the function of region II in DHBV. We scanned region II and the surrounding sequence by using a quantitative encapsidation assay. We found that the sequence between nucleotides (nt) 438 and 720 contributed to efficient pgRNA encapsidation, while the sequence between nt 538 and 610 made the largest contribution to encapsidation. Additionally, deletions between the two encapsidation sequences, epsilon and region II, had variable effects on encapsidation, while substitutions of heterologous sequence between epsilon and region II disrupted the ability of the pgRNA to be encapsidated efficiently. Overall, these data indicate that the intervening sequences between epsilon and region II play a role in encapsidation. We also analyzed heron hepatitis B virus (HHBV) for the presence of region II and found features similar to DHBV: a broad region necessary for efficient encapsidation that contained a critical region II sequence. Furthermore, we analyzed variants of DHBV that were substituted with HHBV sequence over region II and found that the chimeras were not fully functional for RNA encapsidation. These results indicate that sequences within region II may need to be compatible with other viral components in order to function in pgRNA encapsidation.


Assuntos
Avihepadnavirus/química , Capsídeo/metabolismo , Elementos Facilitadores Genéticos , Vírus da Hepatite B do Pato/química , RNA Viral/metabolismo , Animais , Avihepadnavirus/genética , Avihepadnavirus/metabolismo , Aves , Capsídeo/genética , Deleção de Genes , Regulação Viral da Expressão Gênica , Vírus da Hepatite B do Pato/genética , Vírus da Hepatite B do Pato/metabolismo , Análise de Sequência de DNA , Células Tumorais Cultivadas , Virologia/métodos , Montagem de Vírus
16.
J Virol ; 76(15): 7468-72, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12097559

RESUMO

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 by hepatocyte nuclear factor 3 (HNF3). In contrast, HNF3 and HNF4 support duck hepatitis B virus (DHBV) replication in nonhepatoma cells, whereas the RXR alpha-PPAR alpha heterodimer inhibits HNF4-dependent DHBV replication. HNF3 and HNF4 synergistically activate DHBV pregenomic RNA synthesis and viral replication. The conditions that support HBV or DHBV replication in nonhepatoma cells are not able to support woodchuck hepatitis virus replication. These observations indicate that avian and mammalian hepadnaviruses have distinct transcription factor requirements for viral replication.


Assuntos
Avihepadnavirus/fisiologia , Proteínas de Ligação a DNA , Regulação Viral da Expressão Gênica , Orthohepadnavirus/fisiologia , Fatores de Transcrição/metabolismo , Replicação Viral , Células 3T3 , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos , Vírus da Hepatite B do Pato/patogenicidade , Vírus da Hepatite B do Pato/fisiologia , Vírus da Hepatite B/patogenicidade , Vírus da Hepatite B/fisiologia , Fator 4 Nuclear de Hepatócito , Humanos , Fígado/virologia , Camundongos , Fosfoproteínas/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptores do Ácido Retinoico/metabolismo , Receptores X de Retinoides , Transcrição Gênica , Células Tumorais Cultivadas
17.
Virology ; 295(2): 348-59, 2002 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-12033794

RESUMO

We have identified and characterized a novel intracellular DNA replicative intermediate that is synthesized by heron hepatitis B virus (HHBV) and not by other avian hepadnaviruses. The new DNA form is synthesized in all host cells tested. The HHBV nucleic acid template, and not HHBV proteins, is responsible for the formation of the new form. The new form is comprised of a full-length minus-strand DNA and an incomplete plus-strand DNA whose 5' ends are mapped to DR2, predominantly. The 3' ends of its plus-strand are located between nucleotides 946 and 1046. Genetic analysis indicates that the sequences responsible for the formation of the new form lie between nucleotides 910 and 1364. The endogenous polymerase activity of capsids isolated from cells converted the new form into RC DNA. Intracellular capsids containing the new form are secreted inefficiently as virions, in comparison to RC- and DL DNA-containing capsids. Our analysis suggests that the new form is an incomplete RC DNA molecule that is due to a specific block or pause in the synthesis of plus-strand DNA. Our analysis also suggests that capsids become competent for efficient secretion sometime after the synthesis of 1500 nucleotides of plus-strand DNA.


Assuntos
Avihepadnavirus/genética , Aves/virologia , DNA Viral/biossíntese , Replicação Viral , Animais , Avihepadnavirus/fisiologia , Capsídeo , Células Cultivadas , Hepatócitos , Moldes Genéticos , Transcrição Gênica , Células Tumorais Cultivadas , Vírion
18.
J Virol ; 76(9): 4260-6, 2002 May.
Artigo em Inglês | MEDLINE | ID: mdl-11932391

RESUMO

Hepadnaviral reverse transcription requires template switches for the genesis of relaxed circular (RC) DNA, the major genomic form in virions. Two template switches, primer translocation and circularization, are required during the synthesis of the second, or plus, strand of DNA. Studies of duck hepatitis B virus (DHBV) indicate that in addition to the requirement for repeated sequences at the donor and acceptor sites, template switching requires at least three other cis-acting sequences, 5E, M, and 3E. In this study we analyzed a series of variant heron hepatitis B viruses (HHBV) in which the regions of the genome that would be expected to contain 5E, M, and 3E were replaced with DHBV sequence. We found that all single and double chimeras were partially defective in the synthesis of RC DNA. In contrast, the triple chimera was able to synthesize RC DNA at a level comparable to that of unchanged HHBV. These results indicate that the three cis-acting sequences, 5E, M, and 3E, need to be compatible to contribute to RC DNA synthesis, suggesting that these sequences interact during plus-strand synthesis. Second, we found that the defect in RC DNA synthesis for several of the single and double chimeric viruses resulted from a partial defect in primer translocation/utilization and a partial defect in circularization. These findings indicate that the processes of primer translocation and circularization share a mechanism during which 5E, M, and 3E interact.


Assuntos
Avihepadnavirus/metabolismo , Primers do DNA , DNA Circular/genética , DNA Viral/genética , Transcrição Gênica , Animais , Avihepadnavirus/genética , DNA Circular/biossíntese , DNA Viral/biossíntese , Vírus da Hepatite do Pato/genética , Vírus da Hepatite do Pato/metabolismo , Recombinação Genética , Sequências Reguladoras de Ácido Nucleico , Moldes Genéticos , Células Tumorais Cultivadas
19.
Virology ; 289(1): 114-28, 2001 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-11601923

RESUMO

We identified, cloned, and functionally characterized a new avian hepadnavirus infecting storks (STHBV). STHBV has the largest DNA genome of all avian hepadnaviruses and, based on sequence and phylogenetic analysis, is most closely related to, but distinct from, heron hepatitis B virus (HHBV). Unique for STHBV among the other avian hepadnaviruses is a potential HNF1 binding site in the preS promoter. In common only with HHBV, STHBV has a myristylation signal on the S and not the preS protein, two C terminally located glycosylation sites on the precore/core proteins and lacks the phosphorylation site essential for the transcriptional transactivation activity of duck-HBV preS protein. The cloned STHBV genomes were competent in gene expression, replication, and viral particle secretion. STHBV infected primary duck hepatocytes very inefficiently suggesting a restricted host range, similar to other hepadnaviruses. This discovery of stork infections unravels novel evolutionary aspects of hepadnaviruses and provides new opportunities for hepadnavirus research.


Assuntos
Avihepadnavirus/classificação , Avihepadnavirus/isolamento & purificação , Doenças das Aves/virologia , Infecções por Hepadnaviridae/veterinária , Sequência de Aminoácidos , Animais , Avihepadnavirus/genética , Avihepadnavirus/patogenicidade , Sequência de Bases , Doenças das Aves/epidemiologia , Aves/virologia , Western Blotting , Células Cultivadas , DNA Viral/sangue , Ensaio de Imunoadsorção Enzimática , Infecções por Hepadnaviridae/epidemiologia , Infecções por Hepadnaviridae/virologia , Hepatócitos/virologia , Fígado/patologia , Fígado/virologia , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Células Tumorais Cultivadas , Proteínas Virais/química , Proteínas Virais/genética , Vírion/isolamento & purificação
20.
J Virol ; 71(7): 4971-80, 1997 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9188560

RESUMO

Hepatitis B viruses (HBVs) replicate by reverse transcription of an RNA intermediate. Packaging of this RNA pregenome into nucleocapsids and replication initiation depend crucially on the interaction of the reverse transcriptase, P protein, with the cis-acting, 5' end-proximal encapsidation signal epsilon. The overall secondary structure is similar in all of the hepadnaviral epsilon signals, with a lower and an upper stem, separated by a bulge, and an apical loop. However, while epsilon is almost perfectly conserved in all mammalian viruses, the epsilon signals of duck HBV (DHBV) and heron HBV (D epsilon and H epsilon, respectively) differ substantially in their upper stem regions, both in primary sequence and in secondary structure; nonetheless, H epsilon interacts productively with DHBV P protein, as shown by its ability to stimulate priming, i.e., the covalent attachment of a deoxynucleoside monophosphate to the protein. In this study, we extensively mutated the variable and the conserved positions in the upper stem of D epsilon and correlated the functional activities of the variant RNAs in a priming assay with secondary structure and physical P protein binding. These data revealed a proper overall structure, with the bulge and certain key residues, e.g., in the loop, being important constraints in protein binding. Many mutations at the evolutionarily variable positions complied with these criteria and yielded priming-competent RNAs. However, most mutants at the conserved positions outside the loop were defective in priming even though they had epsilon-like structures and bound to P protein; conversely, one point mutant in the loop with an apical structure different from those of D epsilon and H epsilon was priming competent. These results suggest that P protein binding can induce differently structured epsilon RNAs to adopt a new, common conformation, and they support an induced-fit model of the epsilon-P interaction in which both components undergo extensive structural alterations during formation of a priming-competent ribonucleoprotein complex.


Assuntos
Avihepadnavirus/metabolismo , Produtos do Gene pol/metabolismo , Vírus da Hepatite B do Pato/metabolismo , Conformação de Ácido Nucleico , RNA Viral/metabolismo , Animais , Avihepadnavirus/genética , Sequência de Bases , Sítios de Ligação , Sequência Conservada , Vírus da Hepatite B do Pato/genética , Dados de Sequência Molecular , Mutação , RNA Viral/química , Relação Estrutura-Atividade , Montagem de Vírus
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