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Hepatitis C virus infection in spouses of patients with type C chronic liver disease.

OBJECTIVE: Survey for markers of hepatitis C virus (HCV) infection in spouses of patients with HCV-related chronic liver disease. DESIGN: Cross-sectional clinical, serologic, and molecular biological study of spouses of patients with HCV viremia and chronic liver disease. SETTING: University and city hospitals. PARTICIPANTS: Spouses (52 men and 102 women; mean age, 56 +/- 11 years) of 154 patients with HCV viremia (102 men and 52 women; mean age, 58 +/- 10 years), of whom 66 had chronic hepatitis, 49 had liver cirrhosis, and 39 had primary hepatocellular carcinoma. METHODS: Tests for HCV-associated antibodies were done using a second-generation enzyme immunoassay and immunoassays with synthetic oligopeptides deduced from the HCV core gene. Hepatitis C virus RNA was detected by polymerase chain reaction with primers deduced from the 5'-noncoding region and HCV genotypes by reaction with type-specific primers deduced from the HCV core gene. RESULTS: Hepatitis C virus-associated antibodies were detected in 42 (27%) spouses, of whom 25 were also positive for HCV RNA. Of 112 (73%) spouses without detectable antibodies, 2 had chronic liver disease. The development of markers of HCV infection in spouses increased with the duration of marriage, ranging from 1 to 60 years (30 +/- 11 years). CONCLUSIONS: Spouses of patients with HCV viremia and chronic liver disease have an increased risk for acquiring HCV, which is proportional to the duration of marriage. They should be followed routinely for markers of HCV infection and liver disease.

Aged↗

Hepatitis a virus: molecular detection and typing.

Hepatitis A virus (HAV) infection is the leading cause of viral hepatitis throughout the world. HAV infection is mainly propagated via the fecal-oral route, and waterborne and foodborne outbreaks of the disease have been reported.HAV, the prototype of the genus Hepatovirus, belongs to the family Picornaviridae. Its 7.5-kb single-stranded RNA genome bears different distinct regions: the 5' and 3' noncoding regions (NCR), the P1 region, which encodes the structural proteins VP1, VP2, VP3, and a putative VP4, and the P2 and P3 regions encoding nonstructural proteins associated with replication. A single HAV serotype has been described, although seven genotypes have been defined. Since environmental samples usually contain low numbers of viral particles, sensitive methods such as molecular techniques based on nucleic acid amplification are required for their detection. However, even with the adoption of these techniques, the choice of the most adequate target is of relevant importance. The target region should be highly conserved, to increase the chance of detection, and should have an appropriate structure and length to allow sensitivity high enough for these kind of samples. As a target region, we have chosen a fragment of the 5'NCR flanked by highly conserved sequences that have been used for the primer design (forward primer from position 68 to position 85; reverse primer from position 222 to position 240 in the HM175 strain of HAV; GenBank accession number M14707). The internal part of this region, however, may present a certain degree of variation mainly owing to insertions and/or deletions, causing a variable size of the amplimer obtained, i.e., the wild-type HM175 strain gives a size of 174 bp whereas the cell-adapted pHM175 strain gives a size of 186 bp. For this reason it is extremely important to include a confirmative method such as Southern blot hybridization with an internal probe from a region not affected by the insertions/deletions.

Base Sequence↗

Longitudinal study of hepatitis C viremia in chronic hepatitis C.

Serial serum samples from 20 untreated patients with chronic hepatitis C virus (HCV) infection were tested for HCV RNA by a nested polymerase chain reaction assay using primers from the highly conserved 5' noncoding region to determine the relationship between hepatitis C viremia and the activity of liver disease during the natural course of chronic HCV infection. Semiquantitation of serum HCV RNA level was achieved by testing serial 10-fold dilutions of RNA extracts to determine the end-point titer. All the patients were HCV RNA positive at presentation. There was a poor correlation between the initial HCV RNA titer and serum transaminase levels. All patients except one were persistently HCV RNA positive during a follow-up period of 1.5-15 years, although 17 (85%) had periods of normal or near-normal transaminase levels. There was no correlation between changes in the serum transaminase levels and HCV RNA titer. Patients with chronic HCV infection have persistent viremia despite fluctuations in ALT levels.

Adult↗

Fetus-specific expression of a form of cytochrome P-450 in human livers.

The developmentally regulated expression of forms of cytochrome P-450, namely, those encoded by lambda HFL33 and NF25 or HLp cDNAs, which were isolated from respective fetal and adult human liver cDNA libraries, was investigated. When EcoRI fragments of cDNA clones of lambda HFL33 and NF25 were used as probes, these probes hybridized with RNA from both fetal and adult human livers. However, when oligonucleotides specific to the coding and 3'-noncoding region of lambda HFL33 (oli-HFL and oli-HFL3', respectively) were used as probes, these probes gave hybridizable bands with RNA from fetal but not adult livers. On the other hand, an oligonucleotide probe specific to the coding region of NF25 and HLp (oli-NF) gave positive bands with RNA only from adult livers. These results indicate that P-450(HFL33) is expressed specifically in fetal livers and that neither P-450NF nor HLp is expressed in fetal livers, but one or both are expressed in adult livers.

Adult↗

Nucleotide sequence of the 26 S mRNA of the virulent Trinidad donkey strain of Venezuelan equine encephalitis virus and deduced sequence of the encoded structural proteins.

A cDNA clone containing all of the 26 S mRNA coding region of the RNA genome of Venezuelan equine encephalitis (VEE) virus, virulent strain Trinidad donkey (TRD), has been constructed and sequenced. The nucleotide and deduced amino acid sequences of the 26 S RNA of VEE virus conform to the general organization of the alphavirus subgenomic mRNA. Excluding the poly(A) tail, the VEE 26 S RNA is 3913 nucleotides long with a protein coding region of 3762 nucleotides. Codon usage in the translated region is nonrandom and correlates well with that reported for Sindbis (SIN), Semliki Forest (SF), and Ross River (RR) alphaviruses. Highly conserved sequences of 19 to 22 nucleotides representing putative replicase recognition sites occur at the 26 S RNA junction region of the 42 S genomic RNA and at the 3' terminus immediately preceding the poly(A) tail. The conserved sequence at the 26 S/42 S junction region of VEE virus differs from that of other alphaviruses in that an ochre termination codon (UAA) is substituted for a GGU (Gly) codon present in the other viruses. The 5' and 3' noncoding regions (30 and 121 nucleotides, respectively) of the VEE 26 S RNA are shorter than has been reported for several other alphaviruses. The approximate transmembrane domains of the VEE E1 and E2 envelope glycoproteins have been identified. VEE E1 contains a single asparagine-linked glycosylation site, whereas E2 has three such sites, all of which are apparently glycosylated. The deduced amino acid sequence of the VEE polyprotein shows an overall homology of 44 to 46% with the precursor polyproteins of SIN, SF, and RR viruses. VEE virus capsid, E1, and E2 structural proteins show 43 to 46%, 50 to 53%, and 36 to 41% homology, respectively, with the cognate proteins of SIN, SF, and RR viruses.

Amino Acid Sequence↗

Cloning and characterization of a novel RNA-binding protein SRL300 with RS domains.

AT-rich element binding factor 1 (ATBF1) mRNA encodes a transcription factor implicated in neuronal differentiation. A cDNA for the protein that can bind the 5'-noncoding sequence of the ATBF1 mRNA was cloned. The deduced protein, termed SRL300, contains a unique RNA-binding region, two large RS domains and many phosphorylation sites. SRL300 protein was detected in both human and rat cells.

Amino Acid Sequence↗

Substantial portions of the 5' and intercistronic noncoding regions of cowpea chlorotic mottle virus RNA3 are dispensable for systemic infection but influence viral competitiveness and infection pathology.

Cowpea chlorotic mottle virus (CCMV) has a tripartite, positive strand RNA genome. Genomic RNA3 (2.2 kb) encodes the 3a nonstructural protein and the coat protein, which are dispensable for viral RNA synthesis in protoplasts, but required for systemic infection of whole plants. In protoplasts, portions of the 5' and intercistronic noncoding regions of CCMV RNA3 are also dispensable for RNA3 replication and for transcription of the subgenomic coat protein mRNA. To determine whether these noncoding sequences are required for systemic infection, a series of 5' and intercistronic deletions in RNA3 were tested for their effects on the infection of cowpea plants, a natural host of CCMV. The results refine the mapping of the subgenomic mRNA promoter and show that at least 144 bases in the 5' noncoding region and at least 125 bases in the intercistronic noncoding region of CCMV RNA3 are dispensable for systemic infection. For mutants with deletions within these regions, no differences were noted in the rate of infection spread, and the level of virus accumulation in systemically infected tissue 10-14 days postinoculation was 60-100% of wild type (wt). However, the largest viable intercistronic deletion transformed the nearly symptomless appearance of wt CCMV infections to an extensive, bright yellow chlorosis, showing that infection pathology can be altered by mutations with a regulatory rather than a protein-coding character. In addition, neither 5' nor intercistronic deletion mutants competed effectively with wt CCMV in whole plant co-infection experiments; i.e., such mutants were not detectable in systemically infected tissue after co-inoculation with wt CCMV. Thus, although substantial portions of both the 5' and the intercistronic noncoding regions of CCMV RNA3 are dispensable for individual systemic infection, these segments contribute to the competitive fitness of the virus and influence interaction with the host, as evidenced by symptom response.

Base Sequence↗

A polymorphism in the mouse crg-2/IP-10 gene complicates chemokine gene expression analysis using a commercial ribonuclease protection assay.

The use of multiprobe RPAs is becoming an increasingly popular method for the detection and quantitation of RNA levels in cells and tissues. Here we report that due to a polymorphism in the 3'-noncoding region of the mouse Crg-2/IP-10 gene, the mCK-5 chemokine probe set available from Pharmingen can yield aberrant signal patterns with RNA samples from BALB/c, MRL and possibly other mouse strains that may lead to false conclusions regarding expression of the Crg-2/IP-10 and MCP-1 genes.

Animals↗

Hfq, a new chaperoning role: binding to messenger RNA determines access for small RNA regulator.

The Sm-like protein Hfq is involved in post-transcriptional regulation by small, noncoding RNAs in Escherichia coli that act by base pairing. Hfq stabilises the small RNAs and mediates their interaction with the target mRNA by an as yet unknown mechanism. We show here a novel chaperoning use of Hfq in the regulation by small RNAs. We analysed in vitro and in vivo the role of Hfq in the interaction between the small RNA RyhB and its sodB (iron superoxide dismutase) mRNA target. Hfq bound strongly to sodB mRNA and altered the structure of the mRNA, partially opening a loop. This gives access to a sequence complementary to RyhB and encompassing the translation initiation codon. RyhB binding blocked the translation initiation codon of sodB and triggered the degradation of both RyhB and sodB mRNA. Thus, Hfq is a critical chaperone in vivo and in vitro, changing the folding of the target mRNA to make it subject to the small RNA regulator.

Bacterial Proteins↗

RNA binding activity of NIa proteinase of tobacco etch potyvirus.

The C-terminal domain of NIa protein (NIaPro) from tobacco etch potyvirus (TEV) is a sequence-specific proteinase required for processing of the viral polyprotein. This proteinase also interacts with NIb, the TEV RNA-dependent RNA polymerase. NIaPro and two NIaPro-containing polyproteins (NIa and 6/NIa) were analyzed from extracts of recombinant Escherichia coli. Using RNA-protein blot and UV-crosslinking assays, NIaPro and the NIaPro-containing polyproteins were shown to possess RNA-binding activity. NIaPro bound nonspecifically to several RNAs, including plus- and minus-strands of the TEV 5' and 3' noncoding regions. Saturation binding data obtained using the UV-crosslinking assay were consistent with a possible cooperative RNA-binding activity of NIaPro. In addition, the RNA-binding activities of NIaPro and full-length NIa protein were similar. Based on its RNA-binding activity and other known functions, NIaPro or a NIaPro-containing polyprotein is proposed to serve one or more direct roles during TEV RNA synthesis.

Endopeptidases↗

The hepatitis C virus: overview.

Our knowledge of hepatitis C virus (HCV) dates only from 1975, when non-A, non-B hepatitis was first recognized. It was not until 1989 that the genome of the virus was first cloned and sequenced, and expressed viral antigens used to develop serological assays for screening and diagnosis. HCV is in a separate genus of the virus family Flaviviridae. It is a spherical enveloped virus of approximately 50 nm in diameter. Its genome is a single-stranded linear RNA molecule of positive sense and consists of a 5' noncoding region, a single large open reading frame, and a 3' noncoding region. The open reading frame encodes at least three structural and six nonstructural proteins. The genome is characterized by significant genetic heterogeneity, based on which HCV isolates can be classified into six major genotypes and more than 50 subtypes. Even individual isolates of HCV are genetically heterogeneous (quasispecies diversity). Genetic heterogeneity of HCV is greatest in the amino-terminal end of the second envelope protein (hypervariable region 1). This region may represent a neutralization epitope that is under selective pressure from the host's humoral immune response. Infection with HCV proceeds to chronicity in more than 80% of cases, and even recovery does not protect against subsequent re-exposure to the virus. The development of a broadly protective vaccine against HCV will therefore require a better understanding of the molecular biology and immune response to this virus.

Animals↗

Dynamic transcriptome of mice.

Life science in the 21st century is developing rapidly through the structural analysis of biomolecules, the completion of the human genome sequence and the analysis of transcriptomes. The mouse transcriptome has been comprehensively analyzed using a gene discovery approach to collect full-length cDNA (FL-cDNA) clones. The framework of the transcriptome was then mapped out by an international Functional ANnoTation Of Mouse cDNA (FANTOM) effort, and a significant new population of noncoding transcripts was discovered. The geographical analogy of a second "RNA continent," separate from the "continent" of expressed proteins, aids the visualization of this concept. An unexpected number of variations was discovered in the mouse transcriptome. The animal transcriptome has evolved to produce several transcripts and proteins from a single "transcriptional unit". Transcriptome analysis has given rise to the FL-cDNA database and to the 60 770 FANTOM FL-cDNA clone set, and the DNABook was developed as an easier way to distribute these clones. In conjunction with genome sequence databases, transcriptome databases and clone banks will be platforms for developing advanced databases of gene function (e.g. the Genome Function Database). This will enable life science to make rapid progress towards understanding life as a system of molecules.

Animals↗

Cloning, expression and sequence analysis of the classical swine fever virus nucleocapsid protein.

The DNA complementary to the 5'-terminal 1929 nucleotides of classical swine fever virus (CSFV; alias hog cholera virus, HCV) LPC vaccine strain RNA was cloned and sequenced. The sequence encompasses a 5'-noncoding region (NCR) of 264 nucleotides and an open reading frame (ORF) of 1665 nucleotides. The cloned sequence contains genes of four viral proteins, P23, nucleocapsid (core) protein, E0 and part of E1 proteins. Alignment of the 5'-terminal 1929 nucleotides of LPC strain with other strains of CSFV showed well conservation and a homology as high as 84-95% was found between these strains. The cDNA of CSFV-LPC core was cloned into an expression vector, and a fusion protein of 38.5 kDa was obtained which reacted strongly to CSFV antiserum. Purification of the core fusion protein was achieved by a single-step affinity chromatography and the purified product could be recognized by the sera of CSFV-infected swine in ELISA assay. Phylogenetic analysis of the 5'-terminal 1929 nucleotides between pestiviruses revealed that the 5'-end region seems to be suitable for differentiation of different strains of CSFV.

Amino Acid Sequence↗

Human La antigen is required for the hepatitis C virus internal ribosome entry site-mediated translation.

The 5'-noncoding region (5'-NCR) of the hepatitis C virus (HCV) RNA genome serves as an internal ribosome entry site (IRES) and mediates translation initiation in a cap-independent manner. Previously, we reported the interaction between La antigen and the HCV IRES, which appeared to occur in the context of initiator AUG. It was further shown that HCV IRES-mediated translation was stimulated in the presence of human La antigen. In this study, we have defined the cis- and trans-acting elements responsible for La-5'-NCR interactions and established the dependence of the HCV IRES efficiency on cellular La antigen. During the La-IRES interaction, initiator AUG but not the neighboring codons was found to be the direct target of La binding. The C terminus effector domain-dependent modulation of La binding to the HCV IRES is demonstrated by deletion and substitution mutagenesis of the protein. An RNA systematic evolution of ligands by exponential enrichment (SELEX), generated against La protein that selectively binds La in HeLa lysates and competes for the protein binding to the 5'-NCR, was used to demonstrate the requirement of La for the HCV IRES function in the context of mono- and dicistronic mRNAs. Sequestration of La antigen by the RNA SELEX in HeLa translation lysates blocked the HCV and poliovirus IRES-mediated translation in vitro. The functional requirement of La protein for the HCV IRES activity was further established in a liver-derived cell line and in an add-back experiment in which the inhibited IRES was rescued by recombinant human La. These results strongly argue for the novel role of La protein during selection of the initiator AUG and its participation during internal initiation of translation of the HCV RNA genome.

5' Untranslated Regions↗

Alpha2p controls donor preference during mating type interconversion in yeast by inactivating a recombinational enhancer of chromosome III.

Homothallic strains of Saccharomyces cerevisiae can change mating type as often as every generation by replacing the allele at the MAT locus with a copy of mating type information present at one of two storage loci, HML and HMR, located on either end of chromosome III. Selection of the appropriate donor locus is dictated by a mating type-specific repressor protein, alpha2p: Cells containing alpha2p select HMR, whereas those lacking alpha2p select HML. As a repressor protein, alpha2p binds to DNA cooperatively with the transcriptional activator Mcm1p. Here we show that two alpha2p/Mcm1p-binding sites, DPS1 and DPS2, control donor selection. DPS1 and DPS2 are located approximately 30 kb from the left arm of chromosome III, well removed from HML, HMR, and MAT. Precise deletion of only DPS1 and DPS2 results in random selection of donor loci and in a cells without affecting selection in alpha cells. Reciprocally, deletion of only the alpha2p binding segments in each of these two sites results in selection of the wrong donor loci in alpha cells without affecting preference in a cells. These results suggest that Mcm1p, bound to these two sites in the absence of alpha2p, activates HML as donor. Binding of alpha2p blocks the ability of Mcm1p bound to DPS1 and DPS2 to activate HML, resulting in default selection of HMR as donor. DPS1 and DPS2 also regulate expression of several noncoding RNAs, although deletion of at least one of these RNA loci does not affect donor preference. This suggests that transcriptional activation, rather than transcription of a specific product, is the initiating event in activating the left arm of chromosome III for donor selection.

Binding Sites↗

Word frequency analysis reveals enrichment of dinucleotide repeats on the human X chromosome and [GATA]n in the X escape region.

Most of the human genome encodes neither protein nor known functional RNA, yet available approaches to seek meaningful information in the "noncoding" sequence are limited. The unique biology of the X chromosome, one of which is silenced in mammalian females, can yield clues into sequence motifs involved in chromosome packaging and function. Although autosomal chromatin has some capacity for inactivation, evidence indicates that sequences enriched on the X chromosome render it fully competent for silencing, except in specific regions that escape inactivation. Here we have used a linguistic approach by analyzing the frequency and distribution of nine base-pair genomic "words" throughout the human genome. Results identify previously unknown sequence differences on the human X chromosome. Notably, the dinucleotide repeats [AT]n, [AC]n, and [AG]n are significantly enriched across the X chromosome compared with autosomes. Moreover, a striking enrichment (>10-fold) of [GATA]n is revealed throughout the 10-Mb segment at Xp22 that escapes inactivation, and is confirmed by fluorescence in situ hybridization. A similar enrichment is found in other eutherian genomes. Our findings clearly demonstrate sequence differences relevant to the novel biology and evolution of the X chromosome. Furthermore, they implicate simple sequence repeats, linked to gene regulation and unusual DNA structures, in the regulation and formation of facultative heterochromatin. Results suggest a new paradigm whereby a regional escape from X inactivation is due to the presence of elements that prevent heterochromatinization, rather than the lack of other elements that promote it.

Chromosome Mapping↗

The human gene for the regulatory subunit RI alpha of cyclic adenosine 3', 5'-monophosphate-dependent protein kinase: two distinct promoters provide differential regulation of alternately spliced messenger ribonucleic acids.

The present study reports the exon-intron organization of the human RI alpha gene of cAMP-dependent protein kinase and approximately kilobases (kb) of the 5'-flanking region obtained by isolation and sequencing of several phage clones from human genomic libraries. The RI alpha gene is composed of nine coding exons of varying lengths, separated by introns, giving the gene a total length of at least 21 kb. our recent cloning of a processed RI alpha pseudogene with a 5'-noncoding region different from the previously reported RI alpha complementary RNA indicated that the RI alpha gene may have multiple leader exons giving rise to alternately spliced messenger RNAs (mRNAs). Reverse transcription of human testis RNA followed by PCR identified two different RI alpha mRNA species (RI alpha 1a and RI alpha 1b) containing distinct sequences due to alternately splicing the gene. The previously known RI alpha 1b mRNA revealed low constitutive expression in a human B lymphoid cell line (Reh) and was stimulated only 4- to 6-fold by treatment with cAMP. In contrast, very low levels of the novel RI alpha 1a mRNA were present in untreated Reh cells, but were stimulated 40-to 50-fold by cAMP. The 5'-flanking sequence of the RI alpha gene was G/C rich and did not contain any TATA box. Several putative transcription initiation sites were identified in front of each leader exon (exons 1a and 1b) by the 5'-rapid amplification of complementary DNA ends technique. To determine whether the sequences 5' of both leader exons had promoter activities, the 5'-flanking sequences of exons 1a and 1b were inserted in front of a chloramphenicol acetyltransferase reporter gene, and their ability to direct transcription were examined. Transfection of these constructs into rat GH4C1 cells demonstrated that both constructs had promoter activities, as evidenced by high levels of chloramphenicol acetyltransferase activity.

Aged↗

Spatial and temporal divergence of expression in duplicated barley germin-like protein-encoding genes.

Subfunctionalization is the process by which a pair of duplicated genes, or paralogs, experiences a reduction of individual expression patterns or function while still reproducing the complete expression pattern and function of the ancestral gene. Two germin-like protein (GLP)-encoding genes, GerB and GerF, are paralogs that belong to a small gene family in barley (Hordeum vulgare). Both genes share high nucleotide sequence similarity in coding and noncoding regions and encode identical apoplastic proteins. The use of RNA gel blots, coupled with single-stranded conformation polymorphism (SSCP) analysis of RT-PCR products, elucidated the developmental and tissue-specific expression patterns of each gene. Individual expression patterns provided evidence of both overlapping redundancy and early subfunctionalization. GerB is predominantly expressed in developing shoots, while GerF is predominantly expressed in seedling roots, developing spikes, and pericarp/testa. GerF promoter deletion studies located a region (-356/-97) responsible for high promoter activity and showed the ability of GerB and GerF upstream regions to drive gfp expression in coleoptiles, epicarps, and lemma/palea of developing spikes. The observed expression patterns are consistent with proposed roles in plant development and defense mechanisms for this gene family. These roles may explain why redundancy has been selectively maintained in this duplicate gene pair.

Base Sequence↗

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