Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hepatitis E virus (HEV) is the major cause of enterically transmitted non-A, non-B hepatitis in many developing countries and is also endemic in many industrialized countries. Due to the lack of an effective cell culture system and a practical animal model, the mechanisms of HEV pathogenesis and replication are poorly understood. Our recent identification of swine HEV from pigs affords us an opportunity to systematically study HEV replication and pathogenesis in a swine model. In an early study, we experimentally infected specific-pathogen-free pigs with two strains of HEV: swine HEV and the US-2 strain of human HEV. Eighteen pigs (group 1) were inoculated intravenously with swine HEV, 19 pigs (group 2) were inoculated with the US-2 strain of human HEV, and 17 pigs (group 3) were used as uninoculated controls. The clinical and pathological findings have been previously reported. In this expanded study, we aim to identify the potential extrahepatic sites of HEV replication using the swine model. Two pigs from each group were necropsied at 3, 7, 14, 20, 27, and 55 days postinoculation (DPI). Thirteen different types of tissues and organs were collected from each necropsied animal. Reverse transcriptase PCR (RT-PCR) was used to detect the presence of positive-strand HEV RNA in each tissue collected during necropsy at different DPI. A negative-strand-specific RT-PCR was standardized and used to detect the replicative, negative strand of HEV RNA from tissues that tested positive for the positive-strand RNA. As expected, positive-strand HEV RNA was detected in almost every type of tissue at some time point during the viremic period between 3 and 27 DPI. Positive-strand HEV RNA was still detectable in some tissues in the absence of serum HEV RNA from both swine HEV- and human HEV-inoculated pigs. However, replicative, negative-strand HEV RNA was detected primarily in the small intestines, lymph nodes, colons, and livers. Our results indicate that HEV replicates in tissues other than the liver. The data from this study may have important implications for HEV pathogenesis, xenotransplantation, and the development of an in vitro cell culture system for HEV.
...
PMID:Evidence of extrahepatic sites of replication of the hepatitis E virus in a swine model. 1152 25

Hepatitis-splenomegaly (HS) syndrome is an emerging disease in chickens in North America; the cause of this disease is unknown. In this study, the genetic identification and characterization of a novel virus related to human hepatitis E virus (HEV) isolated from bile samples of chickens with HS syndrome is reported. Based upon the similar genomic organization and significant sequence identity of this virus with HEV, the virus has been tentatively named avian HEV in order to distinguish it from human and swine HEV. Electron microscopy revealed that avian HEV is a non-enveloped virus particle of 30-35 nm in diameter. The sequence of the 3' half of the viral genome ( approximately 4 kb) was determined. Sequence analyses revealed that this genomic region contains the complete 3' non-coding region, the complete genes from open reading frames (ORFs) 2 and 3, the complete RNA-dependent RNA polymerase (RdRp) gene and a partial helicase gene from ORF 1. The helicase gene is the most conserved gene between avian HEV and other HEV strains, displaying 58-61% aa and 57-60% nt sequence identities. The RdRp gene of avian HEV shares 47-50% aa and 52-53% nt sequence identities and the putative capsid gene (ORF 2) of avian HEV shares 48-49% aa and 48-51% nt sequence identities with the corresponding regions of other known HEV strains. Phylogenetic analysis indicates that avian HEV is genetically related to, but distinct from, other known HEV strains. This discovery has important implications for HEV animal models, nomenclature and natural history.
...
PMID:Genetic identification and characterization of a novel virus related to human hepatitis E virus from chickens with hepatitis-splenomegaly syndrome in the United States. 1156 38

Samples of serum, tissue and faeces from two pig herds in England were examined for hepatitis E virus by reverse-transcriptase PCR (RT-PCR), and a virus strain from each herd was partially sequenced. Eleven of 42 faecal samples and 16 of 21 tissue samples from two pigs were positive for the virus by RT-PCR. Analysis of two unique but closely related nucleotide sequences obtained from the two herds showed that the viruses clustered in genotype III (6) with a human strain of the virus from an autochthonously acquired case of acute hepatitis in the UK. An ELISA based on recombinant open reading frame 2 (ORF-2) was used to detect antibodies to hepatitis E virus in 256 pig sera from the UK; 85.5 per cent of the samples were positive, compared with 58 per cent of similar samples from Swedish pigs and 23.5 per cent of samples from Dutch pigs.
...
PMID:Evidence for the presence of hepatitis E virus in pigs in the United Kingdom. 1500 46

Hepatitis E virus (HEV) replication is not well understood, mainly because the virus does not infect cultured cells efficiently. However, Huh-7 cells transfected with full-length genomes produce open reading frame 2 protein, indicative of genome replication (6). To investigate the role of 3'-terminal sequences in RNA replication, we constructed chimeric full-length genomes with divergent 3'-terminal sequences of genotypes 2 and 3 replacing that of genotype 1 and transfected them into Huh-7 cells. The production of viral proteins by these full-length chimeras was indistinguishable from that of the wild type, suggesting that replication was not impaired. In order to better quantify HEV replication in cell culture, we constructed an HEV replicon with a reporter (luciferase). Luciferase production was cap dependent and RNA-dependent RNA polymerase dependent and increased following transfection of Huh-7 cells. Replicons harboring the 3'-terminal intergenotypic chimera sequences were also assayed for luciferase production. In spite of the large sequence differences among the 3' termini of the viruses, replication of the chimeric replicons was surprisingly similar to that of the parental replicon. However, a single unique nucleotide change within a predicted stem structure at the 3' terminus substantially reduced the efficiency of replication: RNA replication was partially restored by a covariant mutation. Similar patterns of replication were obtained when full-length genomes were inoculated into rhesus macaques, suggesting that the in vitro system could be used to predict the effect of 3'-terminal mutations in vivo. Incorporation of the 3'-terminal sequences of the swine strain of HEV into the genotype 1 human strain did not enable the human strain to infect swine.
...
PMID:In vitro and in vivo mutational analysis of the 3'-terminal regions of hepatitis e virus genomes and replicons. 1561 30

Hepatitis E is an acute hepatitis casused by hepatitis E virus (HEV) in developing countries, where it occurs as cases sporadic and in epidemics form. The causative agent, hepatitis E virus, is transmitted primarily by the fecal-oral route. HEV is icosahedron non-enveloped virus, and its genome is a single-stranded, positive-sense, 3'-polyadenylated RNA about 7.5 kb in length. It contains three open reading frames (ORFs). Of which ORF1 codes for a polyprotein of 1693 amino acids and contain domains homologous to a viral methyltransferase, a papainlike cysteine protease, an RNA helicasre, and an RNA-dependent RNA polymerase, besides the most hypervariable region of the HEV genome. And ORF3 codes for a 123-amino-acide-long polypeptide with unknown function. While the major viral capsid protein (pORF2, ORF2 codes) of 660 amino acid was showed to contain the protective epitope. The bacterially expressed polypeptide disignated as NE2 has been proved to be a protective antige. And the anti-NE2 monoclonal antibodies (mAb) was screend, two of these mAbs 8C11 and 8H3 were showed to be against separate conformational neutralization epitope of hepatitis E virus (HEV). And these two mAb were used to screen for binding peptides from a 7-peptides phage display library. After four rounds of panning, tweenty-one positive monoclonal phages (11 for 8C11, and 10 for 8H3) were selected and the inserted fragments were sequenced. The DNA sequence coding for the obtained dominant peptide 8C11 (N'-His-Pro-Thr-Leu-Leu-Arg-Ile-C', named 8C11A) and 8H3 (N'-Ser-Ile-Leu-Pro-Tyr-Pro-Tyr-C', named 8H3A) were then synthesized and cloned to insert between amino acid 78 to 83 of hepatitis B core antigen (HBcAg), then expressed in E. coli. The recombinant proteins aggregate into homodimer or polymer on SDS-PAGE, and could bind with mAb 8C11 and 8H3 in Western blotting. Respectively, the recombinant protein C8C11A showed to be dimer mainly, which can bind with mAb 8C11. The monomer and dimer of C8H3A are in the same amount on SDS-PAGE, but only the dimer could bind with mAb 8H3 on Western blotting. The renatured recombinant proteins were all showed to aggregate into virus like particles which were similar as HBcAg on transmission electron micrograph. The dominant peptide 8H3A (N'-Ser-Ile-Leu-Pro-Tyr-ProTyr-C') that selected out by mAb 8H3 was further chemo-synthesized, and its binding activity was confirmed by BIAcore biosensor. The result showed that this 7-peptide can bind with mAb 8H3 in a big Ka and Kd form, which means the binding is not stable. These results implicated that conformational dependent neutralization epitope could be partially modeled by short peptide, which provided a feasible route for subunit vaccine development.
...
PMID:[Selection of a peptide mimic the neutralization epitope of hepatitis E virus with phage peptide display technology]. 1597 79

Some genomic regions for hepatitis E virus (HEV) genotyping have been reported to correlate well with the results from the phylogenetic analyses on the basis of the complete genome. However, few studies have systemically investigated the genomic regions for HEV genotyping using a combined phylogenetic and statistical approach. A consensus region for HEV genotyping has not been determined. In this study the nucleotide identities and genetic distances of 24 partial genomic regions and the complete genome sequences of 37 HEV strains were compared statistically. It was demonstrated with both one-way ANOVA and two-way ANOVA that only one genomic region in RNA-dependent RNA polymerase domain (4254-4560nt) for which there were no significant differences when compared with the full-length genome (P>0.05). The same four genotypes were identified by phylogenetic analysis based on this statistically predicted region identified as for the complete genome. RT-PCR amplification of HEV strains from all four genotypes confirmed conservation of the flanking primer sites of this region. Serum samples from 20 patients with a clinical diagnosis of hepatitis E were further analyzed by PCR using the same primers, 13 were positive and could be classified into genotype 4. These data strongly suggested that this newly identified region could be used for future HEV genotyping.
...
PMID:Hepatitis E virus genotyping based on full-length genome and partial genomic regions. 1647 82

The objective of the present study was to detect hepatitis E virus (HEV) in different samples from naturally infected pigs and to characterise genetically the detected strains. Serum, bile, liver, lymph nodes and faeces of 69 animals from 1 week to 4 months of age with different pathological conditions were collected. Reverse transcriptase-polymerase chain reaction (RT-PCR) to detect HEV and histopathology of tissues was conducted. Positive RT-PCR samples were sequenced and phylogenetically analysed. HEV was detected in at least one sample in 26 out of 69 animals (37.7%). Bile was the most frequently positive sample, followed by mesenteric lymph nodes, liver, faeces and serum. HEV was detected in pigs of 1 (n = 7), 2 (n = 8) and 3 (n = 11) months of age. A total of 22 of 69 (31.9%) pigs had mild to moderate hepatitis and 15 of them were HEV RT-PCR positive in at least one of the tested samples. The highest sensitivity of viral detection was achieved using samples that cannot be obtained from live pigs, such as liver, mesenteric lymph node and bile. Phylogenetic analyses confirmed that all Spanish swine HEV strains detected belonged to genotype III. Therefore, genotype III strains are present in a relative high proportion of pigs between 1 and 3 months of age. Through this study, it cannot be ruled out if concomitant infections may influence the distribution of HEV in infected pigs.
...
PMID:Detection of hepatitis E virus in liver, mesenteric lymph node, serum, bile and faeces of naturally infected pigs affected by different pathological conditions. 1699 12

Hepatitis E, caused by the hepatitis E virus (HEV), is endemic in China. However, the molecular characteristics of HEV circulating in eastern China and the seroprevalence of HEV infection in eastern China are relatively unknown. In this study, 25 HEV strains, isolated from sporadic hepatitis E cases in eastern China, were sequenced in the RNA-dependent RNA polymerase region and subjected to phylogenetic analysis. These HEV strains were 74.6-98.7% identical in nucleotides and were all clustered into HEV genotype 4. Most of them formed new sub-genotypes and revealed a high degree of genetic variance. In addition, 12,052 serum samples were collected from people of different ages, living in urban or rural areas in eastern China. Anti-HEV IgG activity was detected in 2073 (17.20%). The prevalence of anti-HEV IgG significantly increased with age (P<0.0001), ranging from 7.92% in children (<10 years old) to 21.48% among older persons (>or=60 years old). Moreover, statistical analysis showed that there was a significant difference between rural and urban areas, with higher prevalence for people living in rural neighborhoods (P<0.001).
...
PMID:Identification of genetic diversity of hepatitis E virus (HEV) and determination of the seroprevalence of HEV in eastern China. 1713 Oct 64

In this study we tried to find the role of some waterborne viruses in repeated abortion of women. The study includes maternal blood serum and fetal tissue. The serum of full-term delivered women was taken as a control. All collected samples were inoculated on BGM and Hep2G cells to detect entero and Hepatitis E viruses. Enzyme-linked immunosorbent assay was also carried out for IgM and IgG antibodies against HEV in all serum samples. HEV-Ag was determined by dot-ELISA, which used also for enterovirus typing. Reverse transcriptase polymerase chain reaction was used for detection of entero and HE virus RNAs in the collected serum samples. To follow up the source of virus transmission, the wastewater treatment plant which serves the area of samples population was studied at the intake and the final effluent for the presence of hepatitis E virus and enteroviruses with special reference to coxsackieviruses. Wastewater samples were collected for 1 year and for enterovirus concentration the adsorption-elution on nitrocellulose membrane was used and for HEV, two methods of virus concentration were used, urea arginine phosphate buffer (U-APB) and PEG8000. The results of HEV investigation of aborted women sera was 22% for IgG, 3% for IgM, 20% HEV-Ag, and 16% of HEV-RNA by RT-PCR. For fetal tissue, HEV-Ag was detected in 5% of the collected samples. The detected enteroviruses were coxsackieviruses types 2, 3,4 and 5 in all serum samples and wastewater samples. The results showed also, that virus concentration by U-APB is much better than PEG-8000 but not highly efficient.
...
PMID:Waterborne viruses associated with repeated abortion. 1721 39

Previously, we reported that three double-stranded RNA (dsRNA) segments, designated L-, M-, and S-dsRNAs, were detected in Sclerotinia sclerotiorum strain Ep-1PN. Of these, the M-dsRNA segment was derived from the genomic RNA of a potexvirus-like positive-strand RNA virus, Sclerotinia sclerotiorum debilitation-associated RNA virus. Here, we present the complete nucleotide sequence of the L-dsRNA, which is 6,043 nucleotides in length, excluding the poly(A) tail. Sequence analysis revealed the presence of a single open reading frame (nucleotide positions 42 to 5936) that encodes a protein with significant similarity to the replicases of the "alphavirus-like" supergroup of positive-strand RNA viruses. A sequence comparison of the L-dsRNA-encoded putative replicase protein containing conserved methyltransferase, helicase, and RNA-dependent RNA polymerase motifs showed that it has significant sequence similarity to the replicase of Hepatitis E virus, a virus infecting humans. Furthermore, we present convincing evidence that the virus-like L-dsRNA could replicate independently with only a slight impact on growth and virulence of its host. Our results suggest that the L-dsRNA from strain Ep-1PN is derived from the genomic RNA of a positive-strand RNA virus, which we named Sclerotinia sclerotiorum RNA virus L (SsRV-L). As far as we know, this is the first report of a positive-strand RNA mycovirus that is related to a human virus. Phylogenetic and sequence analyses of the conserved motifs of the RNA replicase of SsRV-L showed that it clustered with the rubi-like viruses and that it is related to the plant clostero-, beny- and tobamoviruses and to the insect omegatetraviruses. Considering the fact that these related alphavirus-like positive-strand RNA viruses infect a wide variety of organisms, these findings suggest that the ancestral positive-strand RNA viruses might be of ancient origin and/or they might have radiated horizontally among vertebrates, insects, plants, and fungi.
...
PMID:A novel mycovirus that is related to the human pathogen hepatitis E virus and rubi-like viruses. 1907 34


<< Previous 1 2 3 4 5 Next >>

---