Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A variant of simian immunodeficiency virus from sooty mangabey monkeys (SIVsmm), termed SIVsmmPBj14, was previously identified and shown to induce acute disease and death within 1 to 2 weeks of inoculation of pig-tailed macaques and mangabey monkeys (P. N. Fultz, H. M. McClure, D. C. Anderson, and W. M. Switzer, AIDS Res. Hum. Retroviruses 5:397-409, 1989). SIVsmmPBj14 differed from its parent virus, SIVsmm9, not only in pathogenicity but also in multiple in vitro properties. As a first approach to understanding the biological and molecular mechanisms responsible for the acute disease and death induced by this variant, virus-host cell interactions of SIVsmmPBj14 and SIVsmm9 were studied. Initial rates of replication of the two viruses were identical in primary peripheral blood mononuclear cells (PBMC) from normal pig-tailed macaques and mangabey monkeys, but SIVsmmPBj14 infection always resulted in higher yields of virus than did SIVsmm9 infection, as assessed by levels of reverse transcriptase activity in culture supernatants. Surprisingly, despite its cytopathicity for macaque and mangabey CD4+ cells, replication of SIVsmmPBj14 was accompanied by up to 10-fold increases in number of viable cells compared with cell numbers in uninfected or SIVsmm9-infected cultures. Furthermore, SIVsmmPBj14 was shown to infect and replicate in resting PBMC just as efficiently as in mitogen-stimulated PBMC, irrespective of whether exogenous interleukin-2 (IL-2) or antibodies that neutralized IL-2 were added to culture media. Accumulation of virus in culture supernatants of resting PBMC preceded by several days the appearance of activated cells which expressed the IL-2 receptor alpha subunit (CD25), suggesting that activation of cells was not essential for replication. The ability to activate and to induce simian PBMC to proliferate appeared specific for the acutely lethal variant because incorporation of [3H]thymidine by PBMC from naive animals was observed only upon incubation with concentrated, heat-inactivated SIVsmmPBj14 and not with other viruses. Both CD4(+)- and CD8(+)-enriched cell populations proliferated in response to SIVsmmPBj14. These results are consistent with in vivo observations and suggest that the abilities both to replicate in resting cells and to induce lymphocytes to proliferate may contribute to the extreme virulence of SIVsmmPBj14.
J Virol 1991 Sep
PMID:Replication of an acutely lethal simian immunodeficiency virus activates and induces proliferation of lymphocytes. 187 Feb 5

The expression of the gag-pol polyprotein of human immunodeficiency virus type 1 (HIV-1) occurs via ribosomal frameshifting between the gag and pol genes. Because low levels of the gag-pol precursor are naturally produced in HIV-1-infected cells, a limited amount of information is available on the biology of this molecule. To further study this polyprotein, two mutant HIV-1 proviral genomes were created to position the gag and pol genes in the same translational reading frame. The mutations inserted a single thymidine nucleotide at the site of ribosomal frameshifting (nucleotide 1635), which results in the addition of a phenylalanine residue (frameshift 1 [FS1]), or a single adenine nucleotide, which results in the addition of a leucine residue (frameshift 2 [FS2]). Transfection of the mutant proviral genomes into COS-1 cells resulted in the expression of the p160gag-pol polyprotein precursor as well as the proteolytically processed gag and pol gene products. Metabolic labeling of the transfected cells with [3H]myristic acid revealed that the p160gag-pol and p17gag proteins expressed from the mutant genomes were myristylated. While the supernatants from COS-1 cells transfected with wild-type or mutant proviral genomes contained similar amounts of p24 antigen, the levels of reverse transcriptase were, on the average, 10 times greater in the supernatants from cells transfected with the FS1 and FS2 proviral genomes. The cells transfected with the wild-type proviral genome released infectious viral particles, while the mutant proviral genomes released p24 and reverse transcriptase in the absence of detectable particle formation. The mutant proviral genomes were completely noninfectious as determined by coculture of the transfected COS-1 cells with SupT1 cells. These results demonstrate that the gag-pol polyprotein of HIV-1 contains the appropriate signals for proteolytic processing and association with intracytoplasmic membranes in the absence of virion formation.
J Virol 1991 Sep
PMID:Overexpression of the gag-pol precursor from human immunodeficiency virus type 1 proviral genomes results in efficient proteolytic processing in the absence of virion production. 187 Feb 15

A naturally occurring deletion mutant is observed in plants infected with figwort mosaic virus (FMV), a caulimovirus. The encapsidated mutant genome is formed spontaneously in association with two different strains of FMV in four host plant species. The mutant also appears when cloned wild-type viral DNA is used as the inoculum. The deletion mutant alone is not infectious and it appears unable to replicate after its formation, even in the presence of wild-type virus. The gene for chloramphenicol acetyltransferase was inserted at different positions in the deletion mutant genome, and subsequent transient assays showed that gene expression of the mutant occurs despite the deletion. Sequence analyses of the mutant genome revealed a deletion of 1237-bp segment encompassing a major portion of the coat protein gene and the 5' end of the downstream reverse transcriptase gene. This deletion is associated with consensus signals for RNA splicing including the conserved 5' and 3' splice sites plus surrounding sequences, putative branch point(s) for lariat formation, and an extremely high adenosine content (41%) of the removed fragment. This suggests that splicing of the FMV full-length transcript has occurred prior to reverse transcription and this accounts for the presence and accumulation of encapsidated DNAs with the same deletion.
Virology 1991 Sep
PMID:A naturally occurring deletion mutant of figwort mosaic virus (caulimovirus) is generated by RNA splicing. 187 73

A new method for the detection of RNA in situ is presented. It is based on sequence-dependent annealing of unlabeled specific oligonucleotide primers to intracellular RNA and subsequent chain elongation catalyzed by reverse transcriptase. Under the conditions described, biotin-labeled nucleotides can be incorporated and the cDNA synthesized in situ can thus be detected using fluorescein-conjugated avidin. Compared to traditional in situ hybridization the use of short oligonucleotide primers has the potential advantage of being better to discriminate between closely related RNA transcripts. Compared to in situ transcription with radioactive precursors we find it more attractive to use fluorescein-conjugated avidin as detection system because it allows a more detailed study of cell and signal simultaneously.
Exp Cell Res 1991 Sep
PMID:Nonradioactive, sequence-specific detection of RNA in situ by primed in situ labeling (PRINS). 187 75

We have produced several transgenic mouse lines over-expressing the human ornithine decarboxylase (ODC) gene. We have now characterized one of the transgenic lines as regards the tissue accumulation of the polyamines and the activities of their metabolizing enzymes. Among the tissues analysed, the polyamine pattern was most strikingly changed in testis and brain of the transgenic animals. ODC activity was greatly enhanced in all tissues, except kidney, of the transgenic animals. The most dramatic increase, 80-fold, was found in brain of the transgenic mice. The activities of S-adenosylmethionine decarboxylase and spermidine and spermine syntheses were likewise significantly increased in testis of the transgenic animals. The activities of the enzymes involved in the back-conversion of the polyamines, namely spermidine/spermine acetyltransferase and polyamine oxidase, were similar in the transgenic and non-transgenic animals. As analysed by reverse transcriptase/polymerase chain reaction, all the six tissues of the transgenic animals expressed human-specific ODC mRNA. Determination of the half-life of testicular ODC revealed a stabilization of the enzyme in the transgenic males.
Biochem J 1991 Sep 15
PMID:Characterization of a transgenic mouse line over-expressing the human ornithine decarboxylase gene. 189 76

Inhibition mechanisms of 5'-triphosphates of 3'-azido-3'-deoxythymidine (AZT-TP) and 3'-deoxythymidine (ddTTP) on extensively purified DNA polymerase gamma from bovine testes were examined by analysis of the products synthesized on singly primed M13 single-stranded DNA or synthetic oligonucleotide template-primer in the presence of analogues. The results indicate that AZT-TP inhibits DNA polymerase gamma in competition with dTTP but is not incorporated into DNA, whereas ddTTP is incorporated into DNA and causes chain termination. In contrast, both analogues were used by reverse transcriptase and caused chain termination.
Biochem Biophys Res Commun 1991 Sep 16
PMID:The 5'-triphosphates of 3'-azido-3'-deoxythymidine and 2', 3'-dideoxynucleosides inhibit DNA polymerase gamma by different mechanisms. 189 99

Dipyridamole (DP) is a widely used coronary vasodilator and antithrombotic drug. The presented experiments demonstrate that DP inhibits the replication of HIV-1 and markedly potentiates the anti-HIV activity of azidothymidine (AZT) and dideoxycytidine in CD4-positive cells (monocyte-macrophages and T-lymphocytes). At the same time DP does not potentiate the bone marrow toxicity of AZT, and, in CEM-ss lymphoblastoid cells, it significantly suppresses the cytotoxicity of AZT. Studies on the mechanism of these effects suggest that DP inhibits the intracellular phosphorylation of physiological nucleosides, whereas it does not affect phosphorylation of AZT and other antiviral dideoxynucleoside drugs. This may lead to relative enhancement of the metabolic activation of dideoxynucleoside drugs and the inhibitory action of their active, triphosphate form on HIV reverse transcriptase. Studies comparing the binding of DP to proteins in tissue culture media and in human plasma suggest that in order to achieve significant antiviral potentiation in vivo, high doses of DP will be required.
Orv Hetil 1991 Sep 01
PMID:[A new drug in a new role: dipyridamole in the treatment of HIV-1 infections?]. 192 62

Human immunodeficiency type 1 isolates from 18 initially symptom-free men who were treated with zidovudine for 2 years were investigated for drug sensitivity. At the start all the men had persistent core antigenaemia; the acquired immunodeficiency syndrome developed in 6 during the study. The polymerase chain reaction was used to detect mutations at residue 215 of reverse transcriptase, a mutation associated with reduced drug sensitivity. After 2 years 16/18 isolates were mutant. However, after about 6 months of treatment the mutation was detected in only 7 isolates, 4 from individuals who subsequently had AIDS. Limited direct virus sensitivity data correlated with the genetic data. The rate of appearance of the 215 mutation seemed to correlate with CD4 counts and viral virulence.
Lancet 1990 Sep 08
PMID:Zidovudine sensitivity of human immunodeficiency viruses from high-risk, symptom-free individuals during therapy. 197 78

The nucleotide sequence of the 1206 bp fragment of Pseudomonas aeruginosa DNA coding for the recA gene has been determined. This structure was shown to contain an open reading frame corresponding to a protein with m.w. 36808 D highly homologous (70%) to the Escherichia coli recA protein. Homology on the DNA level is significantly lower (57%) due to the high G/C content characteristics of Pseudomonas DNA. Making use of S1 nuclease and reverse transcriptase it was shown that in P. aeruginosa and E. coli cells recAPA gene transcription starts from A or T unit. Unlike "-35" region, "-10" region is homologous to the consensus E. coli promoter sequence. Comparison of primary structures of the recAPA and recAEC proteins demonstrates that the recAPA protein is by 7 amino acid residues shorter and differs from recAEC at 108 positions. Homology is the lowest in the C-terminal part. Basing on the analysis of hybrid recAPA proteins with a modified C-terminal part, it may be suggested that C-terminus is nonessential for main activities of the recA protein.
Bioorg Khim 1990 Sep
PMID:[Structure of the Pseudomonas aeruginosa recA gene]. 212 86

Five macaques received two vaccinations consisting of soluble human T-cell lymphotropic virus type I proteins from a cell/serum-free human T-cell lymphotropic virus type I-producing cell line. Five other macaques were vaccine controls. All were challenged with a simian T-cell lymphotropic virus type I-producing cell line. The vaccinated macaques generated a strong serological response to challenge as opposed to the control macaques. Western blot analysis of the sera showed that both groups recognized gag and env proteins, but the vaccinate's sera reacted better to the env proteins. Additionally, the antibody produced by both groups had antibody-dependent, complement-mediated cytotoxic activity toward both human and simian T-cell lymphotropic virus type I-infected target cells. The responses of lymphocytes and neutrophils, as measured by lymphocyte blast transformation and chemiluminescence response, respectively, showed no apparent difference between the vaccinates and controls. Testing for reverse transcriptase in lymphocyte supernatants revealed that the controls contained reverse transcriptase activity, while the vaccinates remained negative. The data presented here demonstrate that the vaccine was successful in protecting Macaca nemestrina from simian T-cell lymphotropic virus type I infection.
Cancer Res 1990 Sep 01
PMID:Subunit vaccine protects Macaca nemestrina (pig-tailed macaque) against simian T-cell lymphotropic virus type I challenge. 216 65


<< Previous 1 2 3 4 5 6 7 8 9 10