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Unregulated expression of the erythropoietin receptor gene caused by insertion of spleen focus-forming virus long terminal repeat in a murine erythroleukemia cell line.

A murine erythroleukemia (MEL) cell line, F5-5, expressed 10,000 binding sites for erythropoietin (EPO) per cell, 10-fold more than was expressed by other murine erythroleukemia cell lines and normal erythroid progenitors. Northern (RNA) and Southern blot analyses revealed overexpression of mRNA for the EPO receptor (EPOR) and rearrangement of one of the EPOR gene alleles in F5-5 cells, respectively. Molecular cloning of F5-5-derived cDNA encoding EPOR revealed that the 5' noncoding region of the EPOR cDNA corresponds to the 3' long terminal repeat sequence of the polycythemic strain of Friend spleen focus-forming virus (F-SFFVP). The aberrant EPOR transcripts containing the 3' long terminal repeat sequence were mainly expressed in F5-5 cells. The same integration upstream of the EPOR gene was also observed in other subclones and the parent cell line. It is possible that overexpression of EPOR by viral promoter insertion will confer growth advantage to an F-SFFVP-infected erythroid progenitor cell, leading to positive clonal selection through further leukemogenic steps.

Amino Acid Sequence↗

Non-A, non-B chronic hepatitis is chronic hepatitis C: a sensitive assay for detection of hepatitis C virus RNA in the liver.

To study the role of hepatitis C virus in non-A, non-B chronic hepatitis, 49 liver biopsy samples from 40 patients with non-A, non-B chronic hepatitis and 9 control patients were analyzed by complementary DNA/polymerase chain reaction. Two segments of the HCV genome, one in the nonstructural region and the other in the noncoding region, were amplified by two sets of primer pairs. With use of the nonstructural region primers, hepatitis C virus RNA was detected in 24 (60%) of 40 patients with non-A, non-B chronic hepatitis. Of these 40 patients, RNA was detected in 19 (70%) of 27 patients positive for antibody to hepatitis C virus and in 5 (38%) of 13 patients negative for antibody to hepatitis C virus. However, with the noncoding region primers, hepatitis C virus RNA was detected in 38 (95%) of 40 patients with non-A, non-B chronic hepatitis. Of these patients, the RNA was detected in 26 (96%) of 27 patients positive for antibody to hepatitis C virus and also in 12 (92%) of 13 patients positive for antibody to hepatitis C virus. Hepatitis C virus RNA was not detected in any of the control patients. Sequence analysis showed homology between our samples and the prototype to be only 66% to 77% in the nonstructural region but 99% to 100% in the noncoding region. We conclude that almost all patients with non-A, non-B chronic hepatitis in Japan are currently infected with hepatitis C virus, regardless of the presence or absence of antibody to hepatitis C virus.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗

Complete nucleotide sequence of a beta-cell tropic variant of coxsackievirus B4.

A mouse pancreas-adapted variant of coxsackievirus B4 (P-CB4) has been shown to replicate in, and cause an excessive release of insulin from, pancreatic beta cells cultured in vitro. The prototype CB4 strain (JVB Benschoten), from which the adapted variant was derived, although able to replicate in cultured islets does not cause a similar release of insulin from the beta cells. The pancreas-adapted virus has also been shown to cause host cell protein synthesis shut-off in beta cells and to inhibit (pro)insulin biosynthesis. These metabolic changes occur in the absence of cytolytic damage [Szopa et al.: Bioscience Reports 5:63-69, 1985 and Cell Biochemistry and Function 4:181-187, 1986]. To investigate the genetic basis for this beta cell tropism, the complete nucleotide sequence of P-CB4 has been determined and compared to that of the previously published sequence of the prototype CB4 strain (JVB Benschoten) [Jenkins et al.: Journal of General Virology 68:1835-1848, 1987]. Twenty-five nucleotide sequence differences were observed. Of these, six occur in the 5' noncoding region of the genome and 19 in the coding region (resulting in seven amino acid changes). The possible significance of these changes in relation to the beta cell tropism of the pancreas-adapted virus is discussed.

Base Sequence↗

Sequence of the 3' end of the simian hemorrhagic fever virus genome.

SHFV is a member of a new virus family which includes the genus arterivirus. We have cloned and sequenced 6,314 nt from the 3' end of the SHFV genome. This sequence encompasses nine complete ORFs which is three additional ORFs as compared to the other arteriviruses. We have numbered these ORFs 2a, 2b, 3, 4, 5, 6, 7, 8 and 9. At the 5' end of this sequence is a partial ORF (ORF 1b) of 1590 nt and at the 3' end is a poly(A) tract preceded by a 76 nt noncoding region. The coding capacity for each of the SHFV ORFs as well as the potential mass, pI and number of N-linked glycosylation sites for each of the encoded peptides was determined.

Amino Acid Sequence↗

Sequence determination of hepatitis C virus genome isolated from Taiwan.

The partial genome sequence of the hepatitis C virus (HCV) was determined in the serum of a Taiwanese patient with chronic community-acquired type C hepatitis. The cDNA fragments synthesized with the HCV RNA as a template were amplified by polymerase chain reaction using specific oligonucleotide primers. The amplified fragments represented the regions coding for the putative core, matrix and envelope proteins as well as the N-terminal amino acid sequence of the nonstructural protein NS1, the partial nonstructural NS3 and NS4 proteins and the region of the partial 5'-end noncoding sequence. The cDNA fragments were cloned and sequenced. Sequence analysis of these clones showed that they share 83.7%, 93.2% and 93.6% similarity at the nucleotide level, and 86.6%, 94.1% and 92.9% homology at the amino acid level, with the previously published American, Japanese and Taiwanese isolates, respectively. Accordingly, the RNA genome we obtained is HCV type II, probably, the predominant subtype in Taiwan.

Adult↗

Sequence and translation of the murine coronavirus 5'-end genomic RNA reveals the N-terminal structure of the putative RNA polymerase.

A 28-kilodalton protein has been suggested to be the amino-terminal protein cleavage product of the putative coronavirus RNA polymerase (gene A) (M.R. Denison and S. Perlman, Virology 157:565-568, 1987). To elucidate the structure and mechanism of synthesis of this protein, the nucleotide sequence of the 5' 2.0 kilobases of the coronavirus mouse hepatitis virus strain JHM genome was determined. This sequence contains a single, long open reading frame and predicts a highly basic amino-terminal region. Cell-free translation of RNAs transcribed in vitro from DNAs containing gene A sequences in pT7 vectors yielded proteins initiated from the 5'-most optimal initiation codon at position 215 from the 5' end of the genome. The sequence preceding this initiation codon predicts the presence of a stable hairpin loop structure. The presence of an RNA secondary structure at the 5' end of the RNA genome is supported by the observation that gene A sequences were more efficiently translated in vitro when upstream noncoding sequences were removed. By comparing the translation products of virion genomic RNA and in vitro transcribed RNAs, we established that our clones encompassing the 5'-end mouse hepatitis virus genomic RNA encode the 28-kilodalton N-terminal cleavage product of the gene A protein. Possible cleavage sites for this protein are proposed.

Amino Acid Sequence↗

Nucleotide sequence analysis of cDNA encoding the coat protein of cucumber mosaic virus: genome organization and molecular features of the protein.

The cDNA sequence coding for the coat protein of cucumber mosaic virus (Japanese Y strain) was cloned, and its nucleotide sequence was determined. The sequence contains an open reading frame that encodes the coat protein composed of 218 amino acids. The nucleotide and deduced amino acid sequences of the coat protein of this strain were compared with those of the Q strain; the homologies of the sequences were 78% and 81%, respectively. Further study of the sequences gave an insight into the genome organization and the molecular features of the coat protein. The coding region can be divided into three characteristic regions. The N-terminal region has conserved features in the positively charged structure, the hydropathy pattern and the predicted secondary structure, although the amino acid sequence is varied mainly due to frameshift mutations. It is noteworthy that the positions of arginine residues in this region are highly conserved. Both the nucleotide and amino acid sequences of the central region are well conserved. The amino acid sequence of the C-terminal region is not conserved, because of frameshift mutations, however, the total number of amino acids is conserved. The nucleotide sequence of the 3'-noncoding region is divergent, but it could form a tRNA-like structure similar to those reported for other viruses. Detailed investigation suggests that the Y and Q strains are evolutionarily distant.

Amino Acid Sequence↗

Translational efficiencies of polyomavirus late mRNA molecules that differ in the sequences of their 5' noncoding late leader exons.

Mouse NIH 3T6 cells were coinfected with two strains of polyomavirus that differ only in the sequences of their 5' noncoding late leader exons. Polysomes were isolated at late times after infection and probed with oligonucleotides specific for each strain. Results indicate that the sequence of the late leader does not play a role in the translational efficiency of late polyomavirus messages.

Animals↗

[Gene similarity between hepatitis C virus and human proteins--a blood transfusion problem].

INTRODUCTION: Hepatitis C is a post-transfusion hepatitis which causes serious problems in blood transfusion. Blood testing requires highly sensitive and specific assays with high predictive value. GENOMIC CHARACTERISTICS OF HEPATITIS C VIRUS: According to recommendations of International Association for the study of Liver Diseases etiological diagnosis of hepatitis is based on highly sensitive third generation assays: epitopes in the NS5 region comprising noncoding sequence UTR with 324-341 well conserved pair of homologous basis in 92% HCV genomes, therefore appropriate for virus RNA detection. DEVELOPMENT OF ASSAYS FOR HEPATITIS VIRUS: The first generation of immunoenzyme tests (IET) were based on detection of antibodies on antigen c 100-3, which is a part of the NS4 region of HCV genome. The second generation of tests with two recombinant proteins--c22-3 and c200, achieved higher sensitivity of assays. The third generation included epitopes from NS5 region, and removed the antigen c100-3. DEVELOPMENT OF AUTOIMMUNITY: Autoimmunity is a pathophysiological mechanism that's leads to chronic inflammatory diseases. Autoimunity is characterized by loss of tolerance towards self-antigens. Viral hepatitis C is associated with development of autoimmune phenomena. MOLECULAR MIMICRY: Molecular mimicry, as a mechanism of autoimmunity, was investigated to establish cross-Reactive immune reactions between HCV antigen and human nitrogen-oxide synthase, Tyrosine kinase Lck and hepatic growth factor activator. CROSS REACTIVITY BETWEEN HCV PROTEINS AND HUMAN PROTEINS: HCV capsid proteins initiate the autoimmune process in the liver because of cross reaction of antibodies with human Gor protein 19-27, which causes autoimmune chronic hepatitis. However, analysis of human protein from protein basis Swiss-prot shows homology between NS5 region and 3 human protein nitrogen oxide synthases, tyrosine kinase-Lck, proto-oncogene and hepatic growth factor activator. According to protein data analysis and competitive in vitro experiments, it was concluded that presence of auto-antibodies is probably the consequence of cross reactive immune response. CONCLUSION: Homology of amino acid sequences in the NS5 region of the HCV genome with nitrogen-oxide synthase, tyrosine kinase-Lck, and hepatic growth factor activator, causes auto-immune phenomena in HC, and can be a model for researching autoimmunity and human virus-induced autoimmune diseases.

Autoimmunity↗

Two oncogenes in avian carcinoma virus MH2: myc and mht.

The 5.2-kilobase (kb) RNA genome of avian carcinoma virus MH2 has the genetic structure 5' - delta gag (0.2 kb)-mht (1.2 kb)-myc (1.4 kb)-c(0.4 kb)-poly (A) (0.2 kb)-3'. delta gag is a partial retroviral core protein, mht and myc are cell-derived MH2-specific sequences, and c is the 3'-terminal retroviral vector sequence. the following results were obtained from the complete nucleotide sequences of the mht and myc genes in MH2. (i) delta gag-mht forms a hybrid gene with a contiguous reading frame of 2682 nucleotides that terminates with a stop codon near the 3' end of the mht gene. The 3' 969 nucleotides of mht up to the stop codon are 80% sequence related to the onc-specific raf sequence of murine sarcoma virus 3611 (MSV 3611) (94% homologous at the deduced amino acid level). (ii) The myc coding region in MH2 is preceded by 181 nucleotides derived from the intron immediately upstream from the second exon of the chicken cellular proto-myc gene, followed by an RNA splice acceptor site shared with the proto-myc gene, followed by an RNA splice acceptor site shared with the proto-myc, beyond which it is colinear up to a 3'-termination codon and 40 noncoding nucleotides with the myc sequences of avian retrovirus MC29 and chicken proto-myc. Thus, myc forms, together with a 5' retroviral exon, a second MH2-specific gene. It is concluded that MH2 contains two genes with oncogenic potential, the delta gag-mht gene, which is closely related to the delta gag-raf transforming gene of MSV 3611, and the myc gene, which is related to the transforming gene of MC29. Furthermore, it may be concluded that the cellular proto-onc genes, which on sequence transduction become viral onc genes, are a small group because among the 19 known onc sequences, 5 are shared by different taxonomic groups of viruses of which the mht/raf homology is the closest so far.

Alpharetrovirus↗

Analysis of the complete nucleotide sequence of the picornavirus Theiler's murine encephalomyelitis virus indicates that it is closely related to cardioviruses.

Theiler's murine encephalomyelitis viruses (TMEV) are naturally occurring enteric pathogens of mice which constitute a separate serological group within the picornavirus family. Persistent TMEV infection in mice provides a relevant experimental animal model for the human demyelinating disease multiple sclerosis. To provide information about the TMEV classification, genome organization, and protein processing map, we determined the complete nucleotide sequence of the TMEV genome and deduced the amino acid sequence of the polyprotein coding region. The RNA genome, which is typical of the picornavirus family, is 8,098 nucleotides long. The 5' untranslated region is 1,064 nucleotides long (making it the longest in the picornavirus family after the aphthoviruses) and lacks a poly(C) tract. Computer-generated comparison of the 5' and 3' noncoding regions and polyprotein revealed the highest level of nucleotide and predicted amino acid identity between the TMEV and the cardioviruses encephalomyocarditis virus (EMCV) and Mengo virus. The TMEV polyprotein, which appears to be processed like EMCV since the amino acids flanking the putative proteolytic cleavage sites have been conserved, begins with a short leader peptide followed by 11 other gene products in the standard L-4-3-4 picornavirus arrangement. Because of these similarities, we propose that the TMEV be grouped with the cardioviruses. However, since TMEV and EMCV have different biophysical properties and show no cross-neutralization, they most likely belong in a separate cardiovirus subgroup.

Amino Acid Sequence↗

Substitution rates in hepatitis delta virus.

Substitution rates were estimated for the coding and noncoding regions of the hepatitis delta virus (HDV). The estimated rates of synonymous substitution in HDV were lower than the rates of substitution at non-synonymous sites and in the noncoding region. HDV has lower synonymous substitution rates than the hepatitis C virus, though both are RNA viruses. The relatively low rate of synonymous substitution in HDV may be due to a strong preference of G and C nucleotides at third codon positions. Variation in substitution rate among HDV lineages may be correlated with the clinical development of the HDV-induced hepatitis. The phylogenetic tree inferred for 24 HDV strains reveals similarities between lineages isolated from the same geographic region.

Genome, Viral↗

A poliovirus replicon containing the chloramphenicol acetyltransferase gene can be used to study the replication and encapsidation of poliovirus RNA.

A poliovirus replicon, FLC/REP, which incorporates the reporter gene chloramphenicol acetyltransferase (CAT) in place of the region encoding the capsid proteins VP4, VP2, and part of VP3 in the genome of poliovirus type 3, has been constructed. Transfection of cells indicates that the FLC/REP replicon replicates efficiently and that active CAT enzyme is produced as a CAT-VP3 fusion protein. The level of CAT activity in transfected cells broadly reflects the level of FLC/REP RNA. A series of mutations in the 5' noncoding region of poliovirus type 3 were introduced into FLC/REP, and their effects were monitored by a simple CAT assay. These experiments helped to define further the stem-loop structures in the 5' noncoding region which are essential for RNA replication. The CAT-containing poliovirus replicon could also be packaged into poliovirus capsids provided by helper virus and was stable as a subpopulation of virus particles over at least four passages. The location of the CAT gene in FLC/REP excluded the presence of an encapsidation signal in the region of the poliovirus genome comprising nucleotides 756 to 1805.

Amino Acid Sequence↗

Structural homologies between RNA gene segments 10 and 11 from UK bovine, simian SA11, and human Wa rotaviruses.

The nucleotide sequences of gene segments 10 and 11 from UK bovine rotavirus have been determined. Gene 10 is 751 nucleotides long and contains a single long open reading frame capable of coding for a protein of 175 amino acids. When compared with the published data for gene 10 of the simian rotavirus SA11 and human Wa strains it was found to be more closely related to the SA11 structure (92% nucleotide sequence homology; 97% amino acid sequence homology) than to the human Wa structure (84% nucleotide, 86% amino acid sequence homology). All three strains have two potential N-glycosylation sites in the hydrophobic N terminus of the gene 10 protein. Gene 11 from UK bovine rotavirus is 667 nucleotides long with a single long open reading frame capable of coding for a protein of 198 amino acids. When compared with the published sequence of gene 11 from the human rotavirus Wa, the UK bovine rotavirus gene 11 was found to be one nucleotide longer in the 5'-noncoding region and three nucleotides longer in the coding region. The nucleotide sequence homology was 86%. The predicted proteins coded by segment 11 in UK and Wa rotaviruses are both rich in serine and threonine (23%) and very hydrophilic, but differ appreciably in amino acid sequence (83% homology).

Amino Acid Sequence↗

Secondary structure of the 3'-noncoding region of flavivirus genomes: comparative analysis of base pairing probabilities.

The prediction of the complete matrix of base pairing probabilities was applied to the 3' noncoding region (NCR) of flavivirus genomes. This approach identifies not only well-defined secondary structure elements, but also regions of high structural flexibility. Flaviviruses, many of which are important human pathogens, have a common genomic organization, but exhibit a significant degree of RNA sequence diversity in the functionally important 3'-NCR. We demonstrate the presence of secondary structures shared by all flaviviruses, as well as structural features that are characteristic for groups of viruses within the genus reflecting the established classification scheme. The significance of most of the predicted structures is corroborated by compensatory mutations. The availability of infectious clones for several flaviviruses will allow the assessment of these structural elements in processes of the viral life cycle, such as replication and assembly.

Algorithms↗

Nucleotide sequence of the genome and complete amino acid sequence of the polyprotein of tick-borne encephalitis virus.

The sequence of the genome of tick-borne encephalitis (TBE) virus (Far Eastern subtype, strain Sofjin) coding for structural proteins and nonstructural protein NS1 has been previously reported (A. G. Pletnev, V. F. Yamshchikov, and V. M. Blinov, 1986, FEBS Lett. 200, 317-321; Yamshchikov and Pletnev, 1988, Nucleic Acids Res. 16, 7750. Now we have cloned and sequenced the genomic RNA that encodes all nonstructural proteins. Together with our earlier sequence analyses, these data show that the TBE genome is 10,477 bases in length with a single open reading frame extending from nucleotides 127 to 10,363, encoding 3412 amino acids. The 5'- and 3'-noncoding regions have stem-loop structures. The polyprotein precursor is proteolytically cleaved, apparently by a mechanism resembling that proposed for the expression of polyproteins of the other flaviviruses, such as yellow fever and Kunjin viruses. The deduced TBE gene order is 5'-C-pre(M)M-E-NS1-NS2A-NS2B-NS3-ns4a-NS4B -NS5-3'. The genome structure and the polyprotein of TBE virus is similar to mosquito-borne flaviviruses, although TBE virus is transmitted by ticks. Comparison of the sequence homology of polyproteins of flaviviruses suggests that TBE virus is more closely related to yellow fever virus than to other serological subgroups of flaviviruses. The hydrophobicity profile of the TBE polyprotein is similar to those of other flaviviruses. Nonstructural proteins NS2A, NS2B, ns4a, and NS4B are extremely hydrophobic, suggesting that these proteins are likely associated with cellular membranes. Proteins E, NS1, NS3, and NS5 are the most conserved and these proteins may be involved in the general activities related to viral reproduction.

Amino Acid Sequence↗

Nucleotide sequence of the virulent SA-14 strain of Japanese encephalitis virus and its attenuated vaccine derivative, SA-14-14-2.

The attenuated SA-14-14-2 strain of Japanese encephalitis (JE) virus has been used to immunize people in the People's Republic of China. Oligonucleotide fingerprints of the parent SA-14 and vaccine strain indicate that multiple genetic changes occurred during attenuation of the virus. We have cloned and sequenced the genomes of both the virulent SA-14 and attenuated SA-14-14-2 viruses to define molecular differences in the genomes. Forty-five nucleotide differences, resulting in 15 amino acid substitutions, were found by comparing sequences of the SA-14 and SA-14-14-2 genomes. Transversion of U to A occurred at position 39 in the 5'-noncoding region of SA-14-14-2 and another SA-14 vaccine derivative SA-14-5-3. A single nucleotide change in the capsid gene of SA-14-14-2 altered a single amino acid which changed its predicted secondary structure. A silent nucleotide change was found in the prM gene sequence and the M-protein was unchanged. There are seven nucleotide differences, resulting in five amino acid changes, in the E glycoprotein sequence of the two viruses. Nine amino acid differences were found in the nonstructural proteins of SA-14 and SA-14-14-2: one in NS2A, two in NS2B, three in NS3, one in ns4a, and two in NS5. A single nucleotide change at position 10,428 in the 3'-noncoding region is vaccine virus-specific. The nucleotide and deduced amino acid sequences of the vaccine strain SA-14-14-2, the parent virus SA-14, and virulent strains JaOArS982 and Beijing-1 have been compared and are highly conserved.

Aedes↗

Comparative analysis of the rotavirus NS53 gene: conservation of basic and cysteine-rich regions in the protein and possible stem-loop structures in the RNA.

NS53, the product of rotavirus gene 5, is an RNA-binding protein that contains a cysteine-rich region and is a component of early replication intermediates. To gain information about the structure of NS53 and its RNA, we determined the nucleotide sequence of gene 5 for the human viruses Wa (serotype 1) and DS1 (2) and the simian virus SA11 (3) (Patton strain) and compared them and their deduced amino acid sequences to those reported for the bovine viruses UK (6) and RF (6), SA11 (3) (Both strain), the human virus Rohivg803, and the group C porcine virus PRV. The results showed that gene 5 for human, simian, and bovine strains have lengths of 1564-1567, 1611, and 1579-1581 nucleotides (nt) and encode proteins of 486, 495, and 491 amino acids, respectively. Comparison of the protein sequences for NS53 among different serotypes showed that they are extremely divergent with many sharing amino acid homologies of only 36-38%. Even NS53 from viruses isolated from the same species possessed relatively poor homology, e.g., DS1 versus Wa was 68%. The first 150 amino acids of NS53 exhibited a greater degree of conservation than the rest of the protein. Near the amino terminus, NS53 contains three basic regions and a cysteine-rich domain, suggesting that this area is responsible for the RNA-binding activity of the protein. Present in the cysteine-rich domain of all group A and C viruses was the motif C-X2-C-X8-C-X2-C-X3-H-X-C-X2-C-X5-C. Although this motif may form one or two zinc fingers, the fact that it is highly conserved indicates that it plays a critical role in the function of protein. Comparison of the nucleotide sequences for gene 5 showed that the entire 5'-noncoding region and the first 24 nt of the NS53 ORF are conserved. RNA-folding predictions suggest that this region of the NS53 mRNA can interact with itself, producing a stem-loop structure similar to that found near the 5'-terminus of the NS35 mRNA. Thus, such structures may be common to all rotavirus mRNAs, perhaps functioning as signals for packaging of RNAs into replication intermediates or regulating mRNA translation.

Amino Acid Sequence↗