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

Subviral cores have been prepared from the oncornavirus-like particle found in human milks with the use of phospholipase C and ether or Sterox SL. The major protein of these cores has a molecular weight of 27,000 daltons, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein is found in the core fractions of reverse transcriptase-positive milks and is absent in negative milks. It is distributed in sucrose gradients only in those fractions containing cores and reverse transcriptase activity. The major core protein of the human milk oncornavirus-like particle is electrophoretically identical to the major core protein of the mouse mammary tumor virus.
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PMID:Identification and isolation of the major core protein from the oncornavirus-like particle in human milk. 6 99

A retrovirus antigenically distinct from known type C, B and D viruses was isolated from normal mink (Mustela vison) lung cells that had been co-cultivated with 5-iododeoxyuridine- and dexamethasone-treated dog mammary tumour cells. Cytogenetic studies of the virus-releasing co-culture showed mitotic figures identical to the normal mink cell line (MvlLu) with the exception of a low frequency of cells with extensive chromosomal breakage and uncoiling. The new virus bands at a buoyant density of 1.16 g/ml, contains 60S RNA and a reverse transcriptase which prefers Mn2+ over Mg2+ for the synthesis of DNA. This enzyme utilizes poly(rA).oligo(dT) more efficiently than poly(dA).oligo(dT) and is also able to synthesize DNA copies from the endogenous RNA. Morphologically, it is a typical type C virus. Filtered virus readily infects mink, dog and other mammalian cells indicating the amphotropic nature of its cell growth requirement. Hybridization studies showed that normal mink DNA contains multiple copies of proviral sequences of this newly isolated virus. Serological analyses indicate that the mink endogenous virus contains in its core protein, in addition to the interspecies type-C determinant, an antigenic component related to one of the determinants found in the feline leukaemia virus p30 protein. This determinant is not present in the Rauscher leukaemia virus, RD114 virus or simian sarcoma virus.
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PMID:Characterization of a retrovirus isolated from normal mink cells co-cultivated with a dog mammary tumour. 8 51

Strains of Friend leukemia virus (FLV) that are associated with polycythemia contain the defective spleen focus-forming virus (SFFV). To determine whether the transforming ability of FLV was affected by the presence of this second agent, DBA/2J mouse bone marrow cells were infected in vitro. Criteria for transformation were the establishment of permanent lines, growth on semisolid agarose, and the production of tumors at the site of inoculation in syngeneic hosts. Two lines of immature hematopoietic cells that grow in suspension originated from the infected cultures. Each has an almost diploid karyotype (38-39 chromosomes) and 3-4 metacentric chromosomes. These transformed cells express gp71 viral envelope glycoprotein and p30 viral core protein antigens. Virus production was measured by reverse transcriptase (RNA-dependent DNA polymerase) activity of the virions released into the medium. The virus, assayed in vivo for infectivity, has SFFV activity but is attenuated for leukemogenicity. The stimulation of hemoglobin synthesis in the cells grown in medium supplemented with dimethyl sulfoxide or hexamethylene bisacetamide indicates that the cells are erythroid in origin. SFFV may have a function analogous to erythropoietin in influencing the process of transformation by FLV.
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PMID:In vitro transformation of mouse bone marrow cells by the polycythemic strain of Friend leukemia virus. 8 91

The putative human helper virus SKA-21/A204V, isolated by Nooter et al. in 1977 from human leukemic bone-marrow cells following co-culture with normal fetal canine thymus cells, Cf2th, has been characterized with respect to its major viral core protein, reverse transcriptase, and nucleic acid sequences. The results of these analyses show that this virus is not distinguishable from the woolly monkey type-C virus, SSAV-1, by the techniques employed.
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PMID:Characterization of a type-C virus produced by co-cultures of human leukemic bone-marrow and fetal canine thymus cells. 9 Jun 62

A procedure was established whereby most of the major viral proteins were isolated to apparent homogeneity in biologically and immunologically active forms from a single batch of avian sarcoma virus QV2. For the initial step of purification, gently disrupted virions were fractionated by CsCl centrifugation into envelope proteins, RNA-dependent DNA polymerase, and viral core proteins. Further purification of envelope glycoproteins and DNA polymerase was performed by affinity chromatography on agarose columns cross-linked with plant lectins and poly(C), respectively. On the other hand, core proteins were fractionated by a combination of gel filtration and ion-exchange column chromatography into components p27, p19, and p15. The core protein p15 thus isolated retained proteolytic activity even after storage for 6 months. The present study also demonstrated that QV2 p19 is structurally altered from the corresponding protein of avian myeloblastosis virus (AMV), a reference avian leukosis-sarcoma virus having a well-characterized polypeptide composition.
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PMID:Purification of viral proteins from avian sarcoma virus QV2. 11 57

The use of exclusionary techniques in the procurement of donors for bone allografts greatly reduces chances for disease transmission. Furthermore, treatment of HIV with either chemical agents or strong acids will effectively inactivate the AIDS virus. These data are taken as indirect proof that the risk of obtaining AIDS from a freeze-dried bone allograft is highly remote. The purpose of this study is to obtain direct evidence that the processing of a demineralized freeze-dried bone allograft would render the allograft safe for human use. In Part I, human cortical bone was obtained from a cadaveric source and tested to be free of HIV contamination. The bone was spiked with 5.26 x 10(9) viral particles. This corresponded to 148 micrograms of total viral protein. In Part II, cortical bone was procured from a donor who died of AIDS. In both Parts I and II, the cortical bone was ground to yield particle sizes of 90 to 500 microns. Test samples were treated with a virucidal agent and demineralized in HCl. Control samples were left untreated. All samples were cocultivated with stimulated peripheral blood lymphocytes and assayed for p24 core protein, reverse transcriptase, and viral gag gene by polymerase chain reaction (PCR). In Part I, the HIV spiking experiment, untreated virus infected particulate bone was positive for HIV replication. Treated samples were negative when assayed for HIV. Bone samples in Part II, HIV infected bone, were positive by PCR. Replication of viable HIV could not be demonstrated after treatment. It was concluded that demineralization and treatment with a virucidal agent inactivates HIV in spiked and infected bone.
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PMID:HIV inactivation in a bone allograft. 128 53

Feline immunodeficiency virus (FIV) has morphological, physical and biochemical characteristics similar to human immunodeficiency virus (HIV), the cause of AIDS in man. However, it is antigenically and genetically distinct from HIV; an antigenic relatedness with equine infectious anaemia virus has been demonstrated. FIV has been molecularly cloned and sequenced. Diagnostic tests are commercially available and attempts at preparing inactivated, subunit and molecularly engineered vaccines are being made in different laboratories. During FIV infection a transient primary illness can be recognized, with fever, neutropenia and lymphadenopathy. After a long period of clinical normalcy a secondary stage is distinguished with signs of an immunodeficiency-like syndrome. The incubation period for this stage can be as long as 5 years, during which gradual impairment of immune function develops. Many FIV-infected cats are presented for the first time showing vague signs of illness: recurrent fevers, emaciation, lack of appetite, lymphadenopathy, anaemia, leucopenia and behavioural changes. Later, the predominant clinical signs observed are chronic stomatitis/gingivitis, enteritis, upper respiratory tract infections, and infections of the skin. Neoplasias, neurological, immunological and haematological disorder are seen in a smaller proportion. The immunodeficiency-like syndrome is progressive over a period of months to years. Concomitant infection with feline leukaemia virus has been shown to accelerate the progression of disease. In vitro, phenotypic mixing between FIV and an endogenous feline oncovirus (RD114) has been demonstrated which leads to a broadening of the cell spectrum of the lentivirus. Bovine immunodeficiency virus (BIV) has been isolated only once, and all attempts to obtain additional isolates have failed; it has been recovered from the leucocytes of cattle with persistent lymphocytosis, lymphadenopathy, lesions in the central nervous system, progressive weakness and emaciation. As with the feline representative, BIV also was found to possess a lentivirus morphology and to encode a reverse transcriptase with Mg++ preference; it replicates and induces syncytia in a variety of embryonic bovine tissues in vitro. Antigenic analyses have demonstrated a conservation of epitopes between the major core protein of BIV and HIV. The original isolate has been molecularly cloned and sequenced. Besides the three large open reading frames (ORFs) comprising the gag, pol, and env genes common to all replication-competent retroviruses, five additional small ORFs were found. Numerous point mutations and deletions were found, mostly in the env-encoding ORF. These data suggest that, within a single virus isolate, BIV displays extensive genomic variation.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Animal immunodeficiency viruses. 133 43

Hepatitis B virus (HBV) contains a particle-associated DNA polymerase/reverse transcriptase activity encoded by the P (pol) open reading frame. Due to its low abundance, the corresponding protein has so far escaped direct detection and structural analysis. As a first step to overcome these difficulties, a series of recombinant vaccinia viruses was constructed and used for the synthesis in human hepatoma cells of both the authentic full length protein and of its functional domains. Pulse chase experiments demonstrated that the P-proteins had very short half lives in striking contrast to the viral core protein expressed in parallel with the same system. No evidence was obtained for a specific proteolytic processing of the P-protein as occurring with retroviral pol gene products. Overexpression of P-protein by recombinant vaccinia viruses was then employed to develop a highly sensitive detection method based on the in vitro phosphorylation of newly introduced target sites for protein kinase A. The usefulness of this method was demonstrated in the analysis of encapsidated P-gene products that were transiently expressed from an appropriately modified HBV genome. The results obtained indicate that the P-protein acts unprocessed, at least during the initial steps of nucleocapsid assembly and reverse transcription, and that a fraction of the P-protein molecules is linked as such to the viral DNA. Direct detection of the hepadnaviral P-protein by in vitro phosphorylation should greatly facilitate future analyses on P-protein structure and function.
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PMID:Expression of the P-protein of the human hepatitis B virus in a vaccinia virus system and detection of the nucleocapsid-associated P-gene product by radiolabelling at newly introduced phosphorylation sites. 137 44

Murine monoclonal antibodies (Mabs) to the major core protein p24 of the human immunodeficiency virus type 1 (HIV-1) were tested for their ability to inhibit the replication and spread of the virus in permanent cell cultures (Molt4/8, K37, H9) and in the culture of II-2 stimulated T cells of healthy donors. After addition of ascitic fluid containing monoclonal anti-p24 antibodies or purified anti-p24 antibodies or the respective control to co-cultures of infected and non-infected cells, HIV-1 replication was evaluated by determining the percentage of infected cells and the activity of reverse transcriptase (RT) in cell-free supernatant. In addition, the supernatant's infectivity was determined. FACS analysis demonstrated p24 antigen in about 40% of unfixed HIV-1 infected cells at the cell membrane. Monoclonal anti-p24 antibodies of different epitope specificity added to the cells but not to the virus delayed the spread of HIV-1 infection in permanent cell culture. Furthermore, anti-p24 Mabs inhibited the release of RT-active virus particles by HIV-1 infected cell lines or II-2 stimulated T-lymphocytes, respectively, up to 60%. The mode of action of anti-p24 antibodies after HIV-1 infection is discussed on the basis of the data obtained.
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PMID:Inhibition of HIV-1 infection in vitro by murine monoclonal anti-p24 antibodies. 162 12

cDNA encoding the core protein of rat syndecan was cloned from a neonatal rat aortic cDNA library by polymerase chain reaction amplification. Expression of syndecan mRNA in rat aortic vascular smooth muscle (VSM) cells was demonstrated by reverse transcriptase-linked polymerase chain reaction amplification of syndecan sequences using total RNA from rat aortic VSM cells as templates. Polyclonal antibodies against rat syndecan core protein were produced by immunizing rabbits with a recombinant fusion protein containing a fragment of the extracellular domain. The anti-syndecan antibodies immunoprecipitated a large 35SO4-labeled molecule synthesized by cultured rat aortic VSM cells. The immunoprecipitated molecule was identified as a hybrid proteoglycan, based on results of alkaline, nitrous acid, and chondroitinase ABC digestions. On immunoblots the antibodies recognized a proteoglycan of greater than 200 kDa, with a core protein size after deglycosylation of approximately 50 kDa. The anti-syndecan antibodies stained cultured rat aortic VSM cells as well as tissue sections of neonatal and adult rat aortas in the medial, smooth muscle layer. On Northern blots of RNA isolated from cultured VSM cells, a syndecan cDNA probe hybridized to a major RNA species of 2.6 kilobases. Quantitative Northern blot analysis of total RNA isolated from VSM cells harvested at different cell densities revealed a decrease in syndecan mRNA levels with increased cell density. These results demonstrate the regulated synthesis of syndecan by rat VSM cells.
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PMID:Regulated expression of syndecan in vascular smooth muscle cells and cloning of rat syndecan core protein cDNA. 163 9


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