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)

An earlier finding that lymphocytes from African patients with the acquired immune deficiency syndrome (AIDS) react with rabbit antiserum to purified antigens of bovine leukemia virus (BLV) prompted a study of the possible cross-reactions between a BLV-infected ovine cell line and human lymphocytes inoculated with a strain of lymphadenopathy syndrome-associated virus (LAV). A solid-phase radioimmunoassay was used to detect antigenic markers of the retroviruses. Crude extracts from short-term cultures of lymphocytes infected with LAV bound rabbit antisera to the LAV glycoprotein gp13 (molecular weight 13,000) and the BLV proteins p24 and gp51, but did not bind antibodies to the p24 of human T-cell leukemia virus type I (HTLV-I). Antiserum to LAV gp13 reacted with an ovine cell line producing BLV but also weakly with virus-free ovine cells. Lymphocyte cultures from four African patients with AIDS expressed BLV-related antigens within 6 to 10 days of culture, at the moment when particle-bound reverse transcriptase was produced. BLV-related antigens were induced in lymphocyte cultures from healthy individuals by addition of filtered supernatant or irradiated cells of the original culture. The antisera to BLV used in this study may prove useful for the detection of AIDS-associated viruses in short-term cultures of lymphocytes from AIDS patients or their contacts.
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PMID:Bovine leukemia virus-related antigens in lymphocyte cultures infected with AIDS-associated viruses. 257 33

To study the local immune response to human immunodeficiency virus type 1 (HIV-1) in women infected by or exposed to HIV-1, 75 women were studied: 15 were IgG-seropositive but clinically asymptomatic, 15 had acquired immune deficiency syndrome (AIDS), 15 were IgG-seronegative with seropositive husbands, and 30 were healthy seronegative women who were selected as controls. Serum samples and vaginal secretions were tested for antibodies to HIV-1 IgG and IgA by Western blot analysis. Antibodies of the IgG and IgA classes were detected in serum samples and vaginal secretions from healthy seropositive women and from women with AIDS. Local IgG antibodies to all viral proteins were detected by Western blot tests. Genital IgA antibodies were mainly directed to the core proteins p18 and p25, the p68 reverse transcriptase, and the gp160 and gp41 glycoproteins; IgA antibodies to the glycoprotein gp120 were rarely recovered. Antibodies of both the IgG and IgA classes in genital secretions were directed to all viral proteins, including surface glycoproteins, and could play a role in limiting the virus infectivity on normal mucosa.
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PMID:Antibodies to human immunodeficiency virus in vaginal secretions of heterosexual women. 276 Apr 96

A chemically synthesized peptide corresponding to the amino acid sequence 503-532 of gp160 of human immunodeficiency virus (HIV) was used to generate monoclonal antibodies reactive with the env glycoprotein gp120. One monoclonal antibody, 120-1, was isolated that reacted with the peptide and with HIV antigen(s). Western blot analysis showed reactivity with two bands of 120 kDa and 88 kDa. 120-1 reacted in indirect immunofluorescence with 15-20% of infected human T cell line A3.01 as early as 4 days post in vitro infection, 2-3 days prior to detectable reverse transcriptase activity in supernatant fluids.
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PMID:Human immunodeficiency virus gp120 glycoprotein detected by a monoclonal antibody to a synthetic peptide. 302 2

Human sera from normal and leukemic individuals were found to contain various amounts of an antigen with determinants related to p15E and reverse transcriptase of retroviruses. Using a specific monoclonal antibody and the immuno-affinity purified antigen, we surveyed a series of sera and plasmas from normal individuals and hematological patients by competition radioimmunoassays and binding assays directed against this specific protein. It was detected in all the samples at various levels. The level of this 74-kd glycoprotein appeared to be related to a stimulation of the hematopoietic system. No free antibodies were found that could recognized the labelled purified antigen. Only immune complexes prepared from the blood of some hematological patients contained the specific antigen, but complexes prepared from the blood of normal individuals did not.
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PMID:Detection of a retrovirus-related glycoprotein in immune complexes from patients with hematopoietic disorders. 405 28

The DNA polymerase of the Prague strain of Rous sarcoma virus of subgroup C and of the Schmidt-Ruppin strain of subgroup A has been solubilized. DNA polymerase purified by sucrose gradient sedimentation and chromatography on DEAE-cellulose represented less than 2% of the soluble [(14)C]protein of the virus. The enzyme was separated from 90% of the viral glycoprotein; it is probably different from the viral group-specific antigen. The sedimentation coefficient (s(20, w)) of the soluble DNA polymerase was 8 S before, and 6 S after, incubation with pancreatic RNase. The molecular weight of the 8S DNA polymerase was estimated to be about 170,000, and that of the 6S DNA polymerase to be about 110,000. Purified DNA polymerase had a high activity with 60-70S viral RNA or salmon DNA as template, but it had a low activity with heat-dissociated 60-70S RNA, influenza virus RNA, or the RNA of tobacco mosaic virus as template. Neither the 8S nor the 6S DNA polymerase had endogenous template activity. The DNA-dependent and the RNA-dependent DNA polymerase activities of the Prague strain coincided in sucrose gradients, both in the 8S and the 6S form. It is concluded that the RNA-dependent and the DNA-dependent DNA polymerase activities of the avian tumor viruses are probably due to the same enzyme.
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PMID:Properties of a soluble DNA polymerase isolated from Rous sarcoma virus. 432 88

The primary structure analysis of the gag gene products of human T-cell leukemia virus (HTLV)-ICR has been nearly completed. A comparison of the amino acid sequences with the published nucleotide sequence of HTLV-IATK established that i) p19 which is known to share antigenic determinants with a protein present in normal thymic epithelium, is nevertheless virally coded. ii) The gene order and complete primary structure of the gag precursor (Pr55) which has been shown to be myristylated (My) at its N-terminus is My-p19-p24-p15-OH; and iii) the Pr55gag amino acid sequences of HTLV-ICR and HTLV-IATK are nearly identical showing only a single residue difference in the C-terminal region of p15. Antibodies to synthetic peptides inferred from the nucleotide sequence of the env gene of HTLV-IATK were also raised and used to identify and purify env precursor gPr62-68, surface glycoprotein gp46-51 and transmembrane protein p21. While most of the peptide sera were shown to be subgroup specific some of them detected antigenic determinants shared between protein homologs of viruses of subgroups I and II. Partial or complete amino acid sequences of both the gag and env gene coded proteins of bovine leukemia virus (BLV) structural proteins have also been determined. These extensive protein data together with nucleotide sequences confirm and extend our initial finding that HTLV and BLV are structurally and antigenically related and may have originated from common ancestor. The structural and immunological studies revealed also relationships between HTLV and a number of type C and type D retroviruses studied. One of the highly conserved sequences is shared by the transmembrane proteins of these retroviruses which have been implicated in immunosuppression. It is conceivable that these common regions have common biological function. Two previously unidentified proteins of BLV have also been purified and structurally characterized. Nucleotide sequences capable of coding for related products are present in HTLV. The nature and possible biological functions of these new BLV proteins and the putative HTLV gene products will be discussed. The size and complexity of the genome of the replication competent retroviruses are similar but not identical. The 35S RNA of all replication competent helper viruses is divided into three genes encoding the viral structural proteins: the gag (group-specific antigen) gene codes for the internal structural proteins, the pol (polymerase) gene codes for the enzymes protease, reverse transcriptase and endonuclease and the env (envelope) gene codes for the proteins of the viral envelope.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Structural and antigenic characterization of the proteins of human T-cell leukemia viruses and their relationships to the gene products of other retroviruses. 610 Jun 35

An approach toward elucidation of the mechanisms of action of mammalian leukemia viruses has been made by the generation in tissue culture of recombinant viruses between a potent murine leukemia virus (MuLV), Rauscher-MuLV, and an endogenous xenotropic mouse type-C virus, BALB:virus-2, without known malignant potential. Using a double selection system devised to select against the temperature-sensitive (ts) lesion associated with a mutant of Rauscher-MuLV and the xenotropic host range of BALB:virus-2, recombinant viruses were obtained at frequencies ranging from 0.01 to 0.1%. Recombinant viruses were identified on the basis of the type specific antigenic determinants in the translational products of gag (p15, p12, p30, and p10 proteins), pol (reverse transcriptase), and env (gp70 glycoprotein) genes. By this approach, the partial genetic maps of a large number of recombinants were obtained. The fact that p10 of Rauscher-MuLV ts 25, the mutant utilized, was the only protein uniformly lacking in recombinant viruses, localized the lesion inhibiting gag precursor cleavage in this mutant at the carboxy terminus of its gag gene. The recombinant viruses demonstrated two host range phenotypes as defined by Fv-1 host cell restriction. In each case, NB-tropic recombinants possessed the p30 of BALB:virus-2 p30. Thus, it was possible to assign the site of Fv-1 action at, or closely linked, to the viral p30. The target within the viral genome of a second host restriction was also mapped. A serum factor, previously shown to specifically inactivate xenotropic virus infectivity, was demonstrated to exert its action on the viral env gene product. The system described here allows the generation of specific recombinant genotypes that should be useful in defining those regions of the viral genome involved in leukemogenesis.
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PMID:Viral genes involved in leukemogenesis. I. Generation of recombinants between oncogenic and nononcogenic mouse type-C viruses in tissue culture. 615 14

A proteolytic activity is associated with structural protein p15 in avian RNA tumor viruses. Its effect on the known intracellular viral polyprotein precursors obtained by immunoprecipitation was investigated. Cleavage of Pr76gag resulted in the sequential appearance of p15, p27, and p19. The intracellular precursor Pr180gag-pol was also cleaved by p15, whereas the intracellular glycoprotein precursors of avian RNA tumor viruses, Pr92env, remained unaffected by p15 under all conditions tested. The specificities of the antibodies used to precipitate the precursors influenced the pattern of intermediates and cleavage products obtained by p15 treatment. If virus harvested from the the Prague strain of Rous sarcoma virus, subgroup C-transformed cells at 15-min intervals was incubated at 37 degrees C for further maturation, RNA-dependent DNA polymerase activity showed an optimum of DNA synthesis with 70S viral RNA or synthetic template-primers after short incubation periods. The presence of additional p15 during incubation resulted in a shift of the enzyme activity peak toward earlier time points. Virus harvested at 3-h intervals contained significant amounts of Pr180gag-pol and Pr76gag. The addition of p15 resulted in the cleavage of Pr180gag-pol and Pr76gag, but only a few distinct low-molecular-weight polypeptides appeared. Treatment of purified RNA-dependent DNA polymerase with p15 in vitro resulted in a disappearance of the beta subunit and an enrichment of the alpha subunit. In addition, a polypeptide of 32 x 10(3) molecular weight was generated. The cleavage pattern observed differed from the one obtained by trypsin treatment.
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PMID:Effect of p15-associated protease from an avian RNA tumor virus on avian virus-specific polyprotein precursors. 615 35

An erythroleukemia cell clone, 7C, which failed to produce reverse transcriptase-containing virions or infectious virus, was found to produce noninfectious virus particles by gradient banding of [3H]leucine- and [3H]uridine-labeled virions. The RNA from the 7C virus was shown to consist of the normal 70S size component, which converted to 35S upon heat denaturation. In contrast, the 7C virion proteins showed multiple defects. Analysis of the virion proteins by gel electrophoresis demonstrated that the pr65 gag precursor was incorporated into the 7C virus and that the processing of this precursor was severely diminished. Polymerase proteins pr180gag-pol and pr120pol were also detected in virions, and a third possible polymerase protein, p70, was reduced in size compared to its normal counterpart, p80. Incorporation of the viral gp70 glycoprotein into particles was also reduced 10-fold, despite synthesis and incorporation of gp70 into the 7C cell membrane in normal amounts. Pulse-chase analysis of the synthesis of the viral gag and env proteins in 7C cells showed greatly reduced amounts of pr180gag-pol, pr65gag, p80gag, and p42gag, whereas pr90env, gp70, and spleen focus-forming virus-specific gp55 were synthesized and processed normally. These results suggested that at least one defect in 7C virus was impaired cleavage of gag or pol proteins or both, most likely due to a lack of the appropriate viral protease, and that this lack of cleavage might affect incorporation of gp70 into virus particles.
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PMID:Replication-defective Friend murine leukemia virus particles containing uncleaved gag polyproteins and decreased levels of envelope glycoprotein. 616 68

LA3382 is a temperature-sensitive replication-defective mutant of Rous sarcoma virus that contains four active mutations. In this study we performed experiments to determine the biochemical defect that blocks the synthesis of infections virus late in the replication cycle. At the nonpermissive temperature (41 degrees C) cells infected with LA3382 synthesized virus particles which were noninfectious and exhibited significant reductions in the amounts of gp85 and gp37 present in the virions. An analysis of the intracellular viral polypeptides indicated that the precursor of the viral glycoproteins (Pr95) were synthesized normally but underwent cleavage at a reduced rate at the restrictive temperature. Pr95 did not accumulate in infected cells ans was inserted into mutant virions at 41 degrees C; however, Pr95 was cleaved in such a way that gp85 was released from the viruses and could be detected in the supernatant medium by immunoprecipitation. The virus-free glycoprotein was indistinguishable from wild-type gp85 and may have been released due to an anomalous cleavage. Pulse-chase experiments also indicated that the Pr180 polyprotein precursor of the reverse transcriptase was cleaved to the active form of the enzyme more slowly at 41 degrees C in LA3382-infected cells. This accounted for the twofold lower level of polymerase activity found in mutant virions at 41 degrees C, defect which probably did not account for the observed 20- to 50-fold reduction in infectivity. Furthermore, the replication defect was not complemented by an env deletion mutant Rous sarcoma virus [RSV(-)[, which should complement a pol defect. Therefore, we conclude that the major lesion that impairs replication in LA3382 is within the env gene.
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PMID:Rous sarcoma virus mutant LA3382 is defective in virion glycoprotein assembly. 617


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