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

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

Astroviruses cause outbreaks of diarrhea in children attending day care centers (DCCs). Reverse transcriptase-polymerase chain reaction (RT-PCR) was compared with EIA detection of astrovirus in stool specimens to characterize further the molecular epidemiology of an outbreak of astrovirus-associated gastroenteritis. Three hundred sixty-eight stool specimens collected prospectively from 36 children enrolled in a DCC during an 11-week outbreak of diarrhea were evaluated by EIA and RT-PCR. Astrovirus was detected in 32% of specimens by RT-PCR versus 10% by EIA (P < .001) and in 89% of children by RT-PCR versus 50% by EIA. The median duration of astrovirus excretion episodes detected by EIA was 1.5 days versus 4 days by RT-PCR (P = .06). Astrovirus was excreted for prolonged periods by immunocompetent children during this outbreak. RT-PCR was more sensitive than EIA for detection of astrovirus in stool specimens and redefined the epidemiology of astrovirus infection in this setting.
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PMID:Virologic features of an astrovirus diarrhea outbreak in a day care center revealed by reverse transcriptase-polymerase chain reaction. 759

We have determined the nucleotide sequences of a highly conserved region of the RNA-dependent RNA polymerase of the prototype Snow Mountain agent (SMA) and of four other small, round-structured viruses (antigenically Norwalk virus [NV]-like or SMA-like) following reverse transcription-PCR amplification of viral RNA obtained from human stools. The stool samples were either from volunteers administered SMA or from sporadic cases and outbreaks of gastroenteritis that occurred in Japan and the United Kingdom between 1984 and 1992. The GLPSG and YGDD RNA polymerase motifs were in the proper locations in the sequences of the five SRSVs, but each sequence was distinct from the 8FIIa prototype NV sequence and from each other. Analysis of the sequences and reactivities in a new NV antigen enzyme-linked immunosorbent assay showed that the five viruses could be divided into two groups (serogroups) with NV and SMA, respectively, being the prototypes. The sequences of the capsid region and a nonstructural region (2C) were determined from one strain from each group. One virus (SRSV-KY-89/89/J), isolated in Japan and antigenically similar to the prototype NV (isolated 21 years earlier in Ohio), showed a remarkable level of sequence similarity to NV. KY-89 and the 8FIIa NV showed 87.2% nucleotide similarity over 2,516 continuous nucleotides amounting to 96 to 98.9% amino acid similarity in three distinct domains in two open reading frames. Between the prototype SMA and NV, the polymerase region showed 63% nucleotide and 59% amino acid similarity, respectively. Two other antigenically SMA-like isolates (SRSV-925/92/UK and SRSV-OTH-25/89/J), from the United Kingdom and Japan, showed 80% nucleotide and 88 to 92% amino acid similarity in the polymerase region to the prototype SMA isolated 16 and 13 years earlier in the United States. The capsid region of the antigenically SMA-like OTH-25 virus showed 53% nucleotide and 65% amino acid similarity to the prototype NV capsid region. Domains of sequence diversity and conversation were identified within the capsid protein of these two distinct prototype serotypes of virus. These results indicate that NV-like and SMA-like agents are still circulating, and sequence comparisons will be useful to identify and classify distinct viruses in the NV group.
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PMID:Sequence diversity of small, round-structured viruses in the Norwalk virus group. 805 74

We report the results from sequence analysis and expression studies of the gastroenteritis agent astrovirus serotype 1. We have cloned and sequenced 5,944 nucleotides (nt) of the estimated 7.2-kb RNA genome and have identified three open reading frames (ORFs). ORF-3, at the 3' end, is 2,361 nt in length and is fully encoded in both the genomic and subgenomic viral RNAs. Expression of ORF-3 in vitro yields an 87-kDa protein that is immunoprecipitated with a monoclonal antibody specific for viral capsids. This protein comigrates with an authentic 87-kDa astrovirus protein immunoprecipitated from infected cells, indicating that this region encodes a viral structural protein. The adjacent upstream ORF (ORF-2) is 1,557 nt in length and contains a viral RNA-dependent RNA polymerase motif. The viral RNA-dependent RNA polymerase motifs from four astrovirus serotypes are compared. Partial sequence (2,018 nt) of the most 5' ORF (ORF-1) reveals a 3C-like serine protease motif. The ORF-1 sequence is incomplete. These results indicate that the astrovirus genome is organized with nonstructural proteins encoded at the 5' end and structural proteins at the 3' end. ORF-2 has no start methionine and is in the -1 frame compared with ORF-1. We present sequence evidence for a ribosomal frameshift mechanism for expression of the viral polymerase.
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PMID:Analysis of astrovirus serotype 1 RNA, identification of the viral RNA-dependent RNA polymerase motif, and expression of a viral structural protein. 825 79

The application of the reverse transcriptase polymerase chain reaction (RT-PCR) has enabled several morphologically and physically similar small round structured viruses (SRSVs), including the prototype Norwalk virus (NV), to be classified within the Caliciviridae. This technique, using primers directed to the RNA-dependent RNA polymerase region within the ORF1 of NV, was used to characterise SRSVs associated with epidemic gastroenteritis in adults and sporadic paediatric gastroenteritis in South Africa. Genomic variation was investigated by sequence analysis of the amplified 209bp cDNA region from six isolates and comparison with other characterised SRSVs including NV. Antigenic variation was investigated by the use of the recombinant enzyme immunoassay described recently for the detection of Snow Mountain agent-like antigen in stool specimens. Two distinct antigenic groups were evident with NV-like viruses associated with adult gastroenteritis, and Mexico viruslike viruses associated with paediatric gastroenteritis. Viral isolates from two of the outbreaks of adult gastroenteritis showed a high degree of nucleotide sequence identity with NV, i.e., 84% and 98%, respectively, whereas the paediatric isolates showed 92-95% sequence similarity with the Snow Mountain-like virus, MxV. These data show concordance between antigenic and genomic analyses.
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PMID:Molecular characterisation of small round structured viruses associated with gastroenteritis in South Africa. 863 7

A dot blot hybridization assay was developed for detection of human calicivirus/Sapporo/82/J (HuCV/Sa/82) or strains closely related to HuCV/Sa/82 in stool specimens. The cDNA derived from the RNA-dependent RNA polymerase (RDRP) region of HuCV/Sa/82 was used as a positive probe and the pBR322 DNA as a negative control probe. Both probes were labeled with digoxigenin and the products of hybridization reaction were detected with an anti-digoxigenin antibody-alkaline phosphatase conjugate. This assay was specific for HuCV/Sa/82 and for HuCV antigenically related to HuCV/Sa/82. The lower limit of sensitivity of this assay was estimated to be about 10(5) physical particles or 10 pg of cDNA, similar to that of the previously developed ELISA for HuCV. In 1273 stool specimens obtained from children with acute gastroenteritis in Sapporo, Japan, 110 (8.6%) contained small round structured viruses by EM and 23 (1.8%) were positive for HuCV antigenically related to HuCV/Sa/82 by either the hybridization assay or ELISA. A higher positive rate was obtained with the dot blot assay (21%) than by ELISA (10%), suggesting that the dot blot assay either detects HuCV more broadly than the ELISA or detects HuCV covered with fecal antibodies which interrupt antigen-antibody reactions in the ELISA. Negative results for detection of Norwalk virus (NV) cDNA and feline calicivirus (FCV) RNA by both this assay and the ELISA indicated that the HuCV/Sa/82 strain is distinct antigenically and genetically from NV and FCV.
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PMID:Dot blot hybridization with a cDNA probe derived from the human calicivirus Sapporo 1982 strain. 892 Aug 27

Based on genome analysis of the RNA-dependent RNA polymerase region, it has been proposed that human caliciviruses (HuCV) can be classified into at least three genogroups: genogroup I is represented by Norwalk virus (NV), genogroup II by Snow Mountain agent (SMA) and genogroup III by HuCV/Sapporo/82/Japan (HuCV/Sa/82/J) virus. HuCV/Sa/82/J strain is genetically unique and more closely related to animal caliciviruses than are other known HuCVs, such as NV and SMA. HuCV/Sa/82/J strain was detected in four outbreaks of HuCV gastroenteritis occurring between 1977 and 1982 in an infant home in Sapporo. The HuCVs detected from these four outbreaks all showed a typical "Star of David" configuration by electron microscopy (EM), and they were identical antigenically and genetically. This strain has also been detected in other prefectures in Japan, as well as in the USA, UK, Saudi Arabia and Kenya. Seroepidemiological studies have shown a worldwide distribution of this virus, including Japan, USA, UK, Southeast Asia, Canada, China and Kenya. This virus has been circulating in Sapporo for at least 19 years (1977-1995). HuCV/Sa/82/J strain is thought to be one of the common causes of viral gastroenteritis worldwide. The HuCV/Sa/82/J strain has been detected mainly in infants. Age-related prevalence of antibody to this strain also shows that infections commonly occur in children less than 5 years old, although viruses in the NV and SMA genogroups commonly infect adults. The pattern of acquisition of antibodies to strain HuCV/Sa/82/J is similar to that of other common viral infections. HuCV/Sa/82/J strain is unique virologically and clinically among caliciviruses.
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PMID:The epidemiology of human calicivirus/Sapporo/82/Japan. 901 23

This report describes the characterization of Parkville virus, the etiologic agent of an outbreak of foodborne gastroenteritis, that has the morphology of a calicivirus and genetic properties that distinguish it from previously identified strains in the Sapporo/Manchester virus clade. Sequence analysis of the Parkville virus genome showed it contained the RNA-dependent RNA polymerase motifs GLPSG and YGDD characteristic of members of the family Caliciviridae with an organization identical to that reported for the Manchester virus where the capsid region of the polyprotein is fused to the RNA polymerase. Parkville virus however, demonstrates considerable sequence divergence from both the Manchester and Sapporo caliciviruses, providing the first indications that genetic diversity exists within caliciviruses of this previously homogeneous clade. On the basis of recent advances in the genetic characterization of members of the family Caliciviridae, we propose a new interim phylogenetic classification system in which Parkville virus would be included with Manchester and Sapporo virus as a separate group distinct from the small round-structured viruses (Norwalk-like viruses) that also cause diarrhea in humans.
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PMID:Parkville virus: a novel genetic variant of human calicivirus in the Sapporo virus clade, associated with an outbreak of gastroenteritis in adults. 917 65

From October to December in 1995, an epidemic of infantile gastroenteritis occurred all over Japan except in Hokkaido and Okinawa prefectures. The number of infected infants and young children was estimated to be over 5 million cases [Editorial, IASR 1996]. The stool specimens from patients were examined for the presence of small round structured viruses (SRSVs) by reverse transcription-polymerase chain reaction (RT-PCR) and nucleotide sequencing of parts of the RNA-dependent RNA polymerase region. Thirty-five of 87 stool specimens examined gave positive results. Genomic variation was investigated by sequence analysis of a 327 bp cDNA region. The nucleotide and deduced amino acid sequences of the ten strains segregated into two distinct groups; one showed 96.0-100% nucleotide and 99.1-100% amino acid identity, the others showed 91.4-99.7% nucleotide and 93.5-100% identity. The main mechanism of transmission remains unknown. However, these data suggest the possibility of person-to-person spread by two or more kinds of SRSV.
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PMID:Sequence analysis of SRSV in fecal specimens from an epidemic of infantile gastroenteritis, October to December 1995, Japan. 926 Jun 83

Small round-structured viruses (SRSVs) or Norwalk-like viruses have been implicated as an important causative agent of gastroenteritis outbreaks. We used the relatively newly developed recombinant enzyme immunoassays (EIAs) to determine the seroprevalence of Norwalk virus (NV) and Mexico virus (MxV) in a family-based cohort and an antenatal clinic cohort at Ga-Rankuwa Hospital, Ga-Rankuwa, South Africa. High prevalences (96 to 99%) of anti-NV and anti-MxV antibodies were detected in both cohorts. We also investigated the pattern of antibody acquisition in a cohort of infants and young children without gastroenteritis and found that by 48 months of age all children had acquired adult antibody levels to both these viruses. Lastly, we tested 276 stool specimens collected from infants and young children with gastroenteritis for the presence of NV or MxV antigen by recombinant EIAs to each virus, by electron microscopy (EM), and by reverse transcription (RT)-PCR. NV and MxV antigens were present in 1.8 and 4.3% of the stool specimens, respectively, by the recombinant EIAs; 9.2% were positive for SRSVs by EM, and 25% of these SRSVs gave a positive result by RT-PCR for primer pair 35-36 directed to a region of the RNA-dependent RNA polymerase gene. The seroprevalence studies indicate a high level of exposure to these viruses in both children and adults. Although the viral antigens are not highly prevalent in diarrheal stools, it was determined by the two assays for NV and MxV that children are, nevertheless, infected early in life.
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PMID:Study of Norwalk virus and Mexico virus infections at Ga-Rankuwa Hospital, Ga-Rankuwa, South Africa. 927 20

Human caliciviruses have been reported to be associated with both epidemics of acute diarrhoeal illness and with sporadic cases of gastroenteritis in children. In this study, we report the identification of genogroup II small round-structured viruses or human caliciviruses associated with an outbreak of winter vomiting disease in South Africa. The virus was initially identified by electron microscopic examination of the stools and then further characterised by recombinant immunoassay with expressed capsid proteins to human caliciviruses from genogroups I and II. Both antigenically by the EIA and by sequence analysis of a region of the RNA-dependent RNA polymerase gene, the virus was shown to belong to genogroup II of the human Caliciviridae.
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PMID:Snow mountain-like virus identified in young children with winter vomiting disease in South Africa. 947 83


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