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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumours induced in chickens by inoculation of avian sarcoma viruses are frequently capable of undergoing spontaneous regression. It is only those tumour cells which have been derived from progressively growing neoplasms that are able to produce transforming progeny virus in vitro and to shed into the culture medium antigens which are specifically reactive with the peripheral lymphocytes of sarcoma-bearing hosts. Following multiple passages and extended growth in culture, however, the ability of these tumour cell fluids to stimulate the lymphocytes of sensitized hosts diminishes in concert with the declining capacity of these cells to continue to synthesize fully transforming progeny virus. In certain instances, however, aged tumour cells are able to synthesize particles which contain the enzyme RNA-dependent DNA polymerase yet lack detectable envelope glycoprotein.
J Gen Virol 1979 Feb
PMID:Decreased production of transforming virus and altered antigenic behaviour in cultured avian sarcoma cells. 21 55

An infectious molecular clone of the TM1 strain of feline immunodeficiency virus (FIV) was transfected into each of one feline (CRFK), two simian (COS and Vero) and two human (SW480 and HeLa) non-lymphoid cell lines, and virus production was assayed on feline T lymphoblastoid MYA-1 cells by monitoring reverse transcriptase activity. Infectious virus was produced in CRFK, Vero and HeLa cells, but not in COS and SW480 cells. When the basal promoter activity of the FIV long terminal repeat (LTR) was examined in these cell lines by using a chloramphenicol acetyltransferase assay, the activity correlated with the virus production in each cell line. Furthermore, when the activity of the FIV LTR was compared with those of three primate lentivirus LTRs, the highest activity in all the cell lines examined was produced by the LTR of simian immunodeficiency virus from African green monkey (SIVAGM), suggesting that it has a wide expression range. In COS and SW480 cells, the activity of the FIV LTR was much lower than that of the SIVAGM LTR. These results indicate that, whereas the primary block to FIV infection of certain cells may occur at the cell surface, the FIV LTR may also participate in controlling virus replication, as an intracellular mechanism.
J Gen Virol 1992 Jun
PMID:Production of feline immunodeficiency virus in feline and non-feline non-lymphoid cell lines by transfection of an infectious molecular clone. 131 47

RNA of more than 40 hantavirus isolates, originating from rodents and humans of widely separated geographical areas, was copied to cDNA using reverse transcriptase and amplified by polymerase chain reaction (PCR). A genus-reactive oligonucleotide primer pair, flanking a 365 bp region of the G2 glycoprotein gene, was chosen for genus-reactive PCR. DNA products were digested with 20 restriction endonucleases and cleavage patterns were analysed. For strains of known sequence, the restriction patterns observed were consistent with those predicted from sequence data, demonstrating that the amplified products originated from target virus RNA. Further analyses suggested that all amplified viruses could be easily typed into one of five restriction patterns using only five enzymes. The categories identified by restriction analysis of PCR-amplified cDNA corresponded with serogroups established by plaque-reduction neutralization tests. This method may greatly simplify the identification of new hantavirus isolates.
J Gen Virol 1992 Mar
PMID:Comparison of hantavirus isolates using a genus-reactive primer pair polymerase chain reaction. 134 58

We have used the polymerase chain reaction to analyse Ty1-copia group retrotransposons of flowering plants. All eight species studied contain reverse transcriptase fragments from Ty1-copia group retrotransposons. Sequence analysis of 31 subcloned fragments from potato reveals that each is different from the others, with predicted amino acid diversities between individual fragments varying between 5% and 75%. Such sequence heterogeneity within a single species contrasts strongly with the limited diversity seen in such retrotransposons in yeast and Drosophila. The fragments from the other seven plant species examined are also heterogeneous, both within and between species, showing that this is a general property of this transposon group in plants. Phylogenetic analysis of all these sequences reveals that many of them fall into subgroups which span species boundaries, such that the closest homologue of one sequence is often from a different species. We suggest that both vertical transmission of Ty1-copia group retrotransposons within plant lineages and horizontal transmission between different species have played roles in the evolution of Ty1-copia group retrotransposons in flowering plants.
Mol Gen Genet 1992 Jan
PMID:Extreme heterogeneity of Ty1-copia group retrotransposons in plants. 137 Sep 76

Partial 16S ribosomal ribonucleic acid sequences of five Aerococcus-like organisms originally isolated from patients with urinary tract infections were determined using reverse transcriptase in order to clarify their taxonomic position. Analysis of the sequence data revealed that the clinical isolates represent a hitherto unknown line of descent within the genus Aerococcus. A new species, Aerococcus urinae, is proposed for these isolates. The type strain is NCFB 2893.
J Gen Microbiol 1992 Feb
PMID:Phylogenetic analysis of some Aerococcus-like organisms from urinary tract infections: description of Aerococcus urinae sp. nov. 137 37

Retrovirus-like particles were secreted in a steroid-dependent manner by the human mammary carcinoma cell line T47D. The particles exhibited typical retroviral properties such as their electron microscopic appearance (95 nm in diameter) and occasional budding, sedimentation at 1.14 g/ml, reverse transcriptase activity and genomic RNA. The T47D particles were related to mouse mammary tumour virus (MMTV) as shown by their ultrastructural appearance (B type-like eccentric dense cores and budding), Mg2+ dependence of the reverse transcriptase activity; immunological reactivity with MMTV-directed antibodies (revealing proteins of 63K, 52K, 26K and 18K), and hybridization of particle RNA with MMTV DNA under stringent conditions. Purified particles were able to incorporate deoxynucleoside triphosphates in the absence of an exogenous primer and template, thus indicating the existence of a complete and biochemically functional reverse transcription apparatus (reverse transcriptase, RNA and primer) and the ability to direct endogenous cDNA synthesis. Labelled particle cDNA hybridized strongly to human genomic DNA but not to mouse and cat DNA, thus indicating the human origin of the T47D particles. Furthermore all human DNAs, hybridized with the labelled particle cDNA, showed a uniform hybridization pattern of restriction fragments, indicating the endogenous origin and distribution of the proviral particle DNA in the human genome.
J Gen Virol 1992 May
PMID:Retrovirus-like particles from the human T47D cell line are related to mouse mammary tumour virus and are of human endogenous origin. 137 76

Three families of retrotransposons of rice (Tos1, Tos2, and Tos3) were isolated by using a method based on the sequence conservation of the primer binding site for reverse transcription. This method should be generally applicable for cloning retrotransposon of other plants. One retrotransposon, Tos3-1, was studied in detail. Tos3-1 is 5.2 kb long, has structures common to retrotransposons, such as long terminal repeats (LTR), a primer binding site complementary to the initiator tRNA, a polypurine tract, and generates target sequence duplications flanking the inserted element. Southern blotting analysis showed that sequences homologous to Tos1, 2 and 3 are found in wild rice species as well as in cultivated rice species, but not in maize and tobacco. The copy number and genomic location of the families vary in different strains of one species of wild rice, suggesting that these elements may still be active. Retrotransposons were also screened for by amplification of the reverse transcriptase coding region using the polymerase chain reaction (PCR). At least two types of copia-like elements (Tos4 and Tos5) were found. The total copy number of retrotransposons in the rice genome was estimated to be about 1000. These results suggest that, as in Drosophila, retrotransposons are the major transposon class in rice.
Mol Gen Genet 1992 May
PMID:Retrotransposon families in rice. 137 4

A retrotransposon from the fungal tomato pathogen Cladosporium fulvum (syn. Fulvia fulva) has been isolated and characterised. It is 6968 bp in length and bounded by identical long terminal repeats of 427 bp; 5 bp target-site duplications were found. Putative first- and second-strand primer binding sites were identified. Three long open reading frames (ORFs) are predicted from the sequence. The first has homology to retroviral gag genes. The second includes sequences homologous to protease, reverse transcriptase, RNAse H and integrase, in that order. Sequence comparisons of the predicted ORFs indicate that this element is closely related to the gypsy class of LTR retrotransposons. Races of the pathogen exhibit polymorphisms in their complement of at least 25 copies of the sequence. Virus-like particles which co-sediment with reverse transcriptase activity were observed in homogenates of the fungus. This is the first report of an LTR retrotransposon in a filamentous fungus.
Mol Gen Genet 1992 Jun
PMID:CfT-I: an LTR-retrotransposon in Cladosporium fulvum, a fungal pathogen of tomato. 137 73

Recently, several classes of compounds have been shown to be extremely selective inhibitors of human immunodeficiency virus type 1 (HIV-1) replication in vitro. These include the tetrahydro-imidazo[4,5,1-jk][1,4]-benzodiazepin-2(1H)-one and -thione (TIBO), 1-(2-hydroxyethoxymethyl)-6-(phenylthio)-thymine (HEPT), dipyridodiazepinone, pyridinone and bis(heteroaryl)piperazine derivatives. The hallmark of these new antiviral compounds is a specific interaction with reverse transcriptase (RT) of HIV-1. They are inactive against HIV-2 and any other viruses tested. Here we describe that, in addition to the HIV-1 strains, two simian immunodeficiency virus (SIV) strains from African green monkeys (SIVagm3 and SIVagmTYO-1) are also sensitive to the TIBO class of compounds. TIBO and HEPT derivatives block the replication of SIVagm in cell culture at micromolar concentrations. Kinetics of inhibition of SIVagm RT by TIBO are competitive with respect to the natural substrate (dGTP). Amino acid alignments and site-directed mutagenesis point to the critical role of amino acid residues Y181 and Y188 in the sensitivity of HIV-1 RT and SIVagm RT to inhibition by the TIBO derivatives. Antiviral efficacy studies with this range of compounds and using sensitive SIV strains are now feasible in monkeys.
J Gen Virol 1992 Jul
PMID:Differential inhibitory effects of TIBO derivatives on different strains of simian immunodeficiency virus. 137 81

The proposal that replication of human immunodeficiency virus type 1 (HIV-1), mediated by cell-to-cell transmission of the virus, might bypass de novo reverse transcription was tested by using one-step cell-to-cell and cell-free virus infection systems. Two well characterized reverse transcriptase (RT) inhibitors, azidothymidine at 20 microM and phosphonoformic acid at 100 micrograms/ml, blocked HIV replication completely following both cell-free virus and cell-to-cell transmission infection, as determined from the kinetics of unintegrated viral DNA synthesis and supernatant RT production after virus infection. Our results confirm that de novo reverse transcription is a crucial and mandatory event in HIV-1 replication following cell-to-cell transmission of the virus.
J Gen Virol 1992 Apr
PMID:De novo reverse transcription is a crucial event in cell-to-cell transmission of human immunodeficiency virus. 137 83


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