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)

The response of mouse L cells to infection with wild-type (wt) and temperature-sensitive (ts) mutants of vesicular stomatitis virus was monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to delineate the synthesis of host cell and viral proteins. Experiments utilized transcriptase mutants of complementation group I (ts114 and ts13), a group IV mutant (ts44) that is restricted in total RNA synthesis (RNA-1) but not in primary transcription, and a group II mutant (ts52) variably restricted in RNA synthesis (RNA +/-). L cells infected with ts mutants at permissive temperature exhibited the wt response of progressive inhibition of host cell protein synthesis accompanied by accumulation of all five viral proteins. Mutant ts44 (IV) also switched off cell protein synthesis at restrictive temperature and accumulated all five viral proteins, but with disproportionate ratios of N and G proteins. At restrictive temperature, cells infected with group I ts mutants failed to accumulate any viral protein and did not exhibit significant reduction in host cell protein synthesis. These data suggest that vesicular stomatitis virus inhibits cell protein synthesis at a stage of viral infection after transcription and possibly translation but preceding replication of progeny viral RNA.
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PMID:Differential inhibition of host protein synthesis in L cells infected with RNA - temperature-sensitive mutants of vesicular stomatitis virus. 17 96

The RNA-dependent RNA polymerase induced in BHK 21 cells by infection with foot-and-mouth disease virus has been isolated from the replication complex. It contains a major, virus-coded protein with mol. wt. 56 000 which appears from serological studies and tryptic peptide mapping to be the same as the virus infection associated (VIA) antigen and the protein P56 found in cells infected with the virus. Other virus coded proteins and a host cell protein were present in the partially purified replication complex but were removed by digestion with ribonuclease T1, leaving only the major virus coded protein. The tryptic peptide maps of the VIA antigen of the seven serotypes of the virus were similar, suggesting a high level of conservation in that region of the genome coding for the RNA polymerase of each type.
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PMID:Purification and identification of the RNA-dependent RNA polymerase of foot-and-mouth disease virus. 23 34

A plasmid has been constructed containing the DNA sequences that direct the expression of the aphthovirus RNA-dependent RNA polymerase (virus infection-associated antigen, VIAA) in its native form. The aphthovirus polypeptide was designed to contain only a single additional amino acid, the N-terminal methionine. The recombinant protein has been purified and used in enzyme-linked immunoelectrotransfer blots to detect aphthovirus-specific antibodies in the sera of persistently infected animals. Furthermore, studies were carried out to test the hypothesis that antibodies against other nonstructural antigens appear in the sera of these animals. It was established that antibodies against polypeptides 3A and 3B can serve as complementary markers for late aphthovirus-carrier state detection. The considerable potential of this approach to detect aphthovirus-specific antibodies, when the isolation of infectious virus is not possible, was demonstrated. Negative results were obtained in animals from virus-free areas and in vaccinated cattle. This assay has the added advantage that no infectious or noninfectious virus is involved during antigen production.
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PMID:Expression of the aphthovirus RNA polymerase gene in Escherichia coli and its use together with other bioengineered nonstructural antigens in detection of late persistent infections. 165 2

It is proposed here that a form of intracellular immunity can be devised which would protect cells from virus infection and, in particular, could be used as a treatment for the human immunodeficiency virus (HIV) infected individual. Following in vitro immunization of naive human B lymphocytes with reverse-transcriptase (RT) or HIV transactivator protein (tat), messenger RNA (mRNA) would be isolated from these cells. Using the mRNA molecules as templates, copy DNA (cDNA) molecules encoding the RT or tat-specific immunoglobulins, are prepared and amplified by the polymerase chain reaction. After engineering of the antibody encoding cDNAs to provide appropriate intracellular addressing information, the cDNAs would be used to transfect stem cells of HIV infected individuals in vitro. The presence, in the cytoplasm and nucleus, of antibodies which had been selected to interfere with the reproduction of the virus, would protect these cells from infection. Autologous transplantation of such cells would confer resistance against HIV replication by these stem cells and their progeny in the treated individual. Such a strategy may also be useful against other retroviruses and could provide resistance against retrovirally triggered leukemia.
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PMID:A putative approach for gene therapy against human immunodeficiency virus (HIV). 169 89

The role of respiratory syncytial virus (RS virus) in otitis media with effusion was studied. Reverse transcriptase-polymerase chain reaction (RT-PCR) and nested polymerase chain reaction (Nested PCR) were used to provide accurate methods for detection of RS viral sequences in the otitis media effusion from children. We could find RS viral sequences in 10/12 samples tested which had been collected during and even after natural outbreak of RSV in the community. These observations suggest RS virus as an important factor in the pathogenesis of otitis media with effusion. The disturbance of the local humoral and cell-mediated immune response in the middle ear accompanied with RS virus infection may lead to the development of infection-induced inflammation and ventilatory compromise, development of suppurative and effusion, multiplication of low virulence pathogens and subsequent development of mucosal damage.
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PMID:[Detection of RS viral sequences in otitis media effusion from children]. 175 48

Papaverine, an inhibitor of cAMP phosphodiesterase, reduced yields of infectious vesicular stomatitis virus in HEp-2 cells approximately 100-fold if added to cultures at a concentration of 30 microM before and after virus infection. The extent of papaverine-induced suppression of viral growth was dependent on drug dose and treatment regimen. Cells progressively recovered their viral permissive state after removal of drug. The cyclic nucleotide, cGMP, nullified the inhibitory effect of papaverine if added to cells during drug treatment. Pulse labeling experiments with [35S]methionine showed that papaverine compromises production of all virus-specific proteins in infected cells without adversely affecting host cell protein synthesis. Treatment of cells with papaverine strongly inhibited the production of viral RNA and both cellular RNA and DNA. It was found that VSV causes an immediate but transient stimulation of DNA synthesis in HEp-2 cells which is prevented by papaverine treatment. This drug also selectively blocked primary transcription of VSV in vivo and to a lesser extent in vitro RNA polymerase activity of the virion-bound transcriptase. The finding that papaverine has a strong inhibitory effect on viral biosynthesis including early transcription suggests that VSV replication may depend on host factors that regulate intracellular levels of cyclic nucleotides such as cAMP.
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PMID:Inhibitory effect of papaverine on RNA and protein synthesis of vesicular stomatitis virus. 241 Oct 62

It is clear from previous studies that host transcriptase or RNA polymerase II (pol II) has a role in poxvirus replication. To elucidate the participation of this enzyme further, in this study we examined several parameters related to pol II during the cycle of vaccinia virus infection in L-strain fibroblasts, HeLa cells, and L6H9 rat myoblasts. Nucleocytoplasmic transposition of pol II into virus factories and virions was assessed by immunofluorescence and immunoblotting by using anti-pol II immunoglobulin G. RNA polymerase activities were compared in nuclear extracts containing crude enzyme preparations. Rates of translation into cellular or viral polypeptides were ascertained by labeling with [35S]methionine. In L and HeLa cells, which produced vaccinia virus more abundantly, the rates of RNA polymerase and translation in controls and following infection were higher than in myoblasts. The data on synthesis and virus formation could be correlated with observations on transmigration of pol II, which was more efficient and complete in L and HeLa cells. The stimulus for pol II to leave the nucleus required the expression of both early and late viral functions. On the basis of current and past information, we suggest that mobilization of pol II depends on the efficiency of vaccina virus replication and furthermore that control over vaccinia virus production by the host is related to the content or availability (or both) of pol II in different cell types.
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PMID:Relationship between RNA polymerase II and efficiency of vaccinia virus replication. 264 21

Phosphorylation of rabies virus proteins was followed in vivo and in vitro. The N and M1 proteins were both found to be phosphorylated. The M1 protein was present in the virion in two phosphorylated states, but only the hypophosphorylated form of M1 was found in infected cells. The hypothesis that some of the M1 molecules become hyperphosphorylated during the maturation process by a membrane-bound kinase was examined. The phosphorylation of the viral proteins by the kinase present in purified rabies virions was studied using an in vitro transcriptase assay: under the conditions of the assay, additional phosphate groups were rapidly attached to the N protein. The M1 protein was similarly hyperphosphorylated although more slowly. Whether the hyperphosphorylation of the N protein is responsible for the poor efficiency of the in vitro transcriptase reaction is not clear. No detectable change in the phosphorylation of cellular proteins was observed in the course of rabies virus infection.
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PMID:Phosphorylation of the N and M1 proteins of rabies virus. 299 64

The use of "antisense" RNA is being widely considered to block specific steps in viral infection. We propose here a new "sense" RNA approach to block viral RNA replication in vitro and possibly in vivo. In the turnip yellow mosaic virus (TYMV) system, the recognition site of the viral replicase (RNA-dependent RNA polymerase) is assumed to be located within the 3' end of the RNA genome. Small "sense" RNAs have been obtained by in vitro transcription of the corresponding cloned cDNAs. Replication of TYMV RNA in vitro is shown here to be blocked only by those RNAs that contain the 3' terminal region of the genome.
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PMID:A new 'sense' RNA approach to block viral RNA replication in vitro. 358 87

Persistent measles virus infection of human HEp-2 or L-41 cells was accompanied by pronounced structural and functional changes of isolated intracellular viral nucleocapsids (NCs). The bulk of persistent NCs possessed altered conformation and a "string-of-beads" appearance, contained substantial amounts of subgenomic size RNAs, exhibited reduced transcriptase activity in vitro and lacked infectivity on transfection of susceptible cells. Immunogold staining revealed negligible binding of anti-P protein monoclonal antibodies to the "string-of-beads" type NCs, thus suggesting their non-functional state.
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PMID:Non-infectious morphologically altered nucleocapsids of measles virus from persistently infected cells. 359 84


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