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)

This investigation was designed to compare detection limits for avian leukosis viruses after infection of chicken fibroblasts with decimal dilutions of Rous-associated virus type 1 (RAV-1). At 5, 9, 14, and 19 days postinfection, cells were examined for group-specific (gs) antigens by microtiter complement-fixation (CF) tests for avian leukosis viruses and by radioimmunoassays (RIA) for the major gs antigen having a molecular weight of 27,000 (p27). Culture fluids, collected at the same time periods, were also assayed for reverse transcriptase activities. We found that minimally infected cultures expressed virus proteins within 9 days postinfection regardless of method used. Although p27 RIA was consistently more sensitive than CF or reverse transcriptase assays, sensitivity was only two- to fivefold greater when concentrated suspensions of RAV-0, RAV-1, and RAV-2 were compared. In terms of infectious units, the lowest detectable virus titer was 6 X 10(3) infectious units as determined by RIA end point dilutions. However, our results led us to conclude that when concentrated cell extracts are tested with hamster antiserum, CF is adequate for detecting infection.
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PMID:Comparative study of three methods for detecting avian leukosis viruses. 6 3

Cells infected by Rous-associated virus 61 (RAV-61) contained a precursor-like protein, pr90, that was specifically precipitated by antiserum directed against envelope glycoproteins, gp85 and gp35. Tryptic peptide mapping showed that pr90 contained tryptic sequences of both gp85 and gp35. Pactamycin mapping experiments indicated that the two glycoproteins are translated from the env-mRNA in the order (5') gp85--gp35. The pactamycin mapping experiments also indicated a translational order of p10--(p27, p12)--p15 for the gag proteins; this agreement with the order previously reported from tryptic mapping studies on precursor pr76 of avian myeloblastosis virus implied that the stoichiometry of the core proteins was unchanged when virions were assembled in the presence of pactamycin. The reverse transcriptase proteins, unlike those of the env and gag genes, fell on the right side of the pactamycin map. This result is in accord with the idea that most, if not all, of the reverse transcriptase protein is translated by read-through of the gag(pol) message rather than by translation of a hypothetical pol-mRNA devoted solely to synthesis of that protein.
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PMID:Proteins of Rous-associated virus 61, an avian retrovirus: common precursor for glycoproteins gp85 and gp35 and use of pactamycin to map translational order of proteins in the gag, pol, and env genes. 7 10

From the same batch of virus, the four major avian viral structural proteins p27, p19, p15, and p12, the reverse transcriptase, the envelope glycoprotein gp85, and the high molecular weight 70 S RNA have been recovered. All proteins, except for gp85, have been purified by use of column chromatography procedures to apparent homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gels and isoelectric focusing. A new isolation procedure for p12 by affinity column chromatography takes advantage of its nucleic acid binding properties. The recovery of nondenatured viral structural proteins is demonstrated by the proteolytic activity revealed by p15. The purified proteins were used for the production of monospecific antibodies. The 70 S RNA served as source for the isolation of 35 S RNA subunits.
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PMID:The isolation of avian viral RNA and polypeptides. 8 39

The genetic compositions of two independently derived preparations of the Bratislava-77 strain (B77) of Rous sarcoma virus were analyzed after each was passaged seven or more times in duck embryo fibroblasts. RNase, T1-resistant oligonucleotide fingerprint analysis of virion RNA from both preparations of duck-passaged B77 revealed the presence of two large noncontiguous deletions. Approximately 75% of the RNAs contained a deletion which spans oligonucleotides 304 to 4 on the viral genome (about 3,500 nucleotides) and encompasses all of the B77 polymerase gene. More than 90% of the RNAs also contained a deletion which spans src-specific oligonucleotides 6 and 5(about 2,200 nucleotides) and is identical to the deletion observed in transformation-defective B77. Virion RNA from duck-passaged B77 also contained two oligonucleotides (D1 and D2) not observed in the RNA of B77 virus grown on chicken embryo fibroblasts. Analysis of the virion RNA of duck-passaged B77 by denaturing agarose gel electrophoresis revealed four major subunits with molecular weights of 3.40 x 10(6), 2.65 x 10(6), 2.25 x 10(6), and 1.55 x 10(6). Whereas the 3.40- and 2.65-megadalton (Mdal) RNA species comigrated with the nondefective and transformation-defective RNAs of B77 propagated on chicken embryo fibroblasts, no counterparts to the 2.25- and 1.55-Mdal RNAs were observed in the RNA of B77 grown on chicken embryo fibroblasts. Oligonucleotide fingerprint analysis of these RNA species revealed that the 2.65-Mdal RNA contains the src-specific deletion and that 2.25-Mdal RNA contains the polymerase region deletion; both of these deletions were observed in the 1.55-Mdal RNA, which was the major RNA subunit species detected in duck-passaged B77. The new oligonucleotides (D1 and D2) observed in the duck-passaged virus were present in the 2.25- and 1.55-Mdal RNA species in vitro and in vivo and directs the synthesis of a 130,000-dalton protein (p130). p130 contains antigenic determinants specific for p27 (gag gene) and gp85 (env gene) but does not contain sequences which cross-react with antisera directed against the alpha beta form of RNA-dependent DNA polymerase (pol gene). This RNA, therefore, is generated by a fusion of the gag and env genes of Rous sarcoma virus B77.
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PMID:Deletion mutant of the Bratislava-77 strain of Rous sarcoma virus containing a fusion of the group-specific antigen and envelope genes. 9 86

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

An African lioness from the Zoo of Zurich had to be euthanized because of an inoperable tumor. The serum tested negative for feline leukemia virus (FeLV) p27 antigen by enzyme-linked immunosorbent assay (ELISA) but was strongly positive for feline immunodeficiency virus (FIV) antibodies by ELISA and Western blot. When her only offspring and mate were tested for FIV, high antibody titers to FIV were also found in their serum. Lymphocytes were prepared from these two lions on different occasions and co-cultivated with specific pathogen free (SPF) cat lymphocytes in the presence of concanavalin A and recombinant human interleukin-2 (IL-2) for 6 weeks. The cell culture supernatants tested negative for Mg(2+)-dependent reverse transcriptase and FIV p24 by a double antibody sandwich ELISA throughout the culture period. Whole blood and buffy coat cells collected from these two lions were transmitted by intraperitoneal injection into two SPF cats. The two cats did not seroconvert for a period of 11 months nor could reverse transcriptase activity and FIV p24 antigen be demonstrated in the supernatant of several lymphocyte cultures. To determine the importance of lentivirus infections in zoo-kept wild felids, 124 serum samples were obtained from African lions, Indian and Siberian tigers, snow leopards, panthers, cheetahs and other wild cats from nine European zoos. In addition, serum samples collected from 12 Asiatic lions originating from Gir forest in the Indian State of Gujarat were included in this study. The sera were tested for antibodies to FIV, FeLV and feline syncytium-forming virus (FeSFV) by ELISA and Western blot using the respective viruses after gradient purification. In addition, some of the sera were also tested for antibodies to equine infectious anemia virus (EIAV) and Visna-Maedi virus (VMV). Antibodies to FIV were found in 30/53 (57%) of African lions, one of 18 tigers and one of four panthers. All other sera including those collected from the 12 Asiatic lions were negative for FIV antibodies. Some of the FIV positive lion sera had high antibody titers producing strong bands on Western blot strips even in dilutions of >> 1:1000. The Western blot pattern of the lion sera differed from that of domestic cats in that primarily p24 and to a lesser degree p17 was recognized. Antibodies to FeSFV were found in 14 animals (seven with strong, seven with intermediate, reaction). No correlation was found between FIV and FeSFV infection. Antibodies to FeLV were found in two cheetahs which later turned out to have been vaccinated with Leukocell, a FeLV vaccine.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Retrovirus infections in non-domestic felids: serological studies and attempts to isolate a lentivirus. 133 98

A cell line (BsT) established from neoplastic embryonal tissues of the platyfish (Xiphophorus maculatus) released spontaneously retrovirus-like particles. The particles have a buoyant density of 1.16 g/ml, a mean diameter of 100 nm and the morphology of immature retroviruses. The particle-associated proteins p70, p65, and p28 react with an antiserum directed against the major internal feline leukemia virus structural protein p27. The particles are associated with a reverse transcriptase. The purified enzyme has a molecular weight of about 70 kDa and prefers the template primers poly(rA):oligo(dT), poly(dC):oligo(dG), and poly(rC):oligo(dG) in the presence of Mn2+. The enzyme activity is inhibited by antibodies directed against the reverse transcriptase of feline leukemia virus and simian sarcoma virus. The particles contain a ribonucleic acid of about 70 S. In an endogenous reverse transcriptase reaction nucleic acids in the range of 0.2 to 0.4 kb were synthesized. In Northern blots with these nucleic acids as probe, three transcripts of about 8.5, 4.2, and 1.5 kb were detected in BsT cells. Southern blot analysis with the same probe demonstrates related sequences in the DNA of BsT cells and the platyfish and swordtail (Xiphophorus helleri). Hybridization experiments with the LTR-gag region of the feline leukemia virus show homologous sequences in the Xiphophorus genome.
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PMID:Isolation and characterization of a retrovirus from the fish genus Xiphophorus. 137 84

A culture of rhesus monkey peripheral blood lymphocytes was divided into two parts; one was kept as an uninfected control, and the other was infected with a strain of simian immunodeficiency virus (SIVmac251) originally isolated from a rhesus monkey that died of a malignant lymphoma associated with acquired immune deficiency syndrome. Both cultures were sampled at successive intervals from 1 to 40 days postinfection. Each sample was subjected to in situ hybridization for detection of viral mRNA, immunocytochemical detection of viral core protein (p27), reverse transcriptase assay, electron microscopy, and immunophenotypic characterization of infected cells. These techniques were used to define viral growth kinetics of this novel lentivirus in peripheral blood lymphocytes. The first evidence of SIVmac251 replication was obtained by an in situ hybridization signal for viral mRNA at 2 days postinoculation. This was followed by detection of viral p27 core protein by immunocytochemistry on day 4. Reverse transcriptase activity above control values was not detected until day 8. Budding particles were not found in the infected cultures until 14 days postinfection. Results of in situ hybridization, immunocytochemistry, and reverse transcriptase assay indicated that two bursts of viral replication occurred during the course of this study. The first, at 3 weeks postinfection, was due to infection and subsequent depletion of CD4+ lymphocytes, while the second, 3 weeks later, resulted from a cycle of replication in CD8+ lymphocytes and the remaining CD4+ cells, culminating in the death of all cells on day 39 postinoculation.
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PMID:Study of long-term cultures of simian immunodeficiency virus (SIVmac 251)-infected peripheral blood lymphocytes. 169 33

The prevalence of simian immunodeficiency virus (SIV), simian T-cell lymphotropic virus type 1 (STLV-I), and type D retrovirus (SRV-D) antibodies was determined for 1229 rhesus monkeys (Macaca mulatta) from two research colonies. Serum samples were tested by using enzyme-linked immunosorbent assay (ELISA), immunoblot (IB), and radioimmunoprecipitation assay (RIPA). Seropositive results for the three retroviruses tested were 0 for SIV, 270 (22%) for STLV-I, and 103 (8.4%) for type D retrovirus. Of the rhesus monkey sera, 61 (5.0%) were reactive to SIV gag p27 only, when tested by IB, but were negative when further tested by RIPA. Virus isolation was attempted from cultured peripheral blood mononuclear cells of 35 monkeys whose sera contained only p27 reactivity and none were positive by reverse transcriptase and core antigen assays to detect SIV. No overt clinical signs of immunodeficiency disease or unexplained deaths were evident in either monkey colony. Additionally, 63 of 165 (38%) human sera from various groups (primate center workers, normal donors, health care workers) had weak to moderate IB reactivity only to SIV p27, but 31 of 31 sera tested were negative by RIPA. These sera remained reactive to SIV p27 following absorption with an uninfected cell lysate, after blocking IB strips with various blocking solutions and were reactive to different SIV antigen preparations while remaining negative to human immunodeficiency virus type 1 (HIV-1) by IB and negative to HIV-2 by ELISA. These data underscore the need to adopt criteria for a positive SIV serologic test requiring reactivity against more than one viral gene product. These results also illustrate a potential problem in the testing of human sera for antibodies against simian retroviruses and demonstrate the need for caution in the interpretation of immunoblot results.
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PMID:SIV, STLV-I and type D retrovirus antibodies in captive rhesus macaques and immunoblot reactivity to SIV p27 in human and rhesus monkey sera. 170 6

Nasal exudate and tumour tissue from goats with enzootic nasal tumours were shown to contain a reverse transcriptase activity associated with a particle of buoyant density typical of retroviruses. The same particle contained a 25,000 Mr protein that cross-reacted with the p27 of Mason-Pfizer monkey virus (MPMV) and with p25 of sheep pulmonary adenomatosis retrovirus. It also contained a low Mr protein related to p10-12 of MPMV.
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PMID:Enzootic nasal tumour of goats: demonstration of a type D-related retrovirus in nasal fluids and tumours. 171 43


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