Biomedical subjects
Publications and source records attributed to R J Avery.
A Kirsten sarcoma virus transformed mouse cell line was found to contain a deleted provirus. RNA from the virus produced by these cells was characterized by hybridisation protection oligonucleotide fingerprinting and was found to be a simple deletion.
The comparative bioavailability of two formulations of 250 mg flucloxacillin sodium capsules in eight fasted healthy volunteers was examined. There were no significant differences in the peak serum concentrations, time to peak concentration or area under the curves with the two formulations indicating that the two batches studied did not differ in bioavailability. The serum elimination half-life of flucloxacillin was 1.31-1.39 hours, and six hours after administration of a single 250 mg dose the serum concentration of flucloxacillin was 0.46 micrograms/ml.
Explore the source record for details and available documents.
We have characterized the virion RNA species of Kirsten sarcoma (KiSV) and Kirsten leukemia (KiLV) viruses released from a clonally related series of mouse cells (14). We have identified the KiLV and KiSV genome RNAs. In addition to the viral RNA species we find large amounts of a virus-like RNA (VL30 RNA), which is heterogeneous and shows variability in its expression. The amount of VL30 RNA in virions does not correlate with the state of transformation of the cells releasing the virus or the ability of the virus to transform other cells. Characterization of RNA rescued from non-producer cells has revealed a sarcoma virus (KiSV CB3) with an oligonucleotide fingerprint different from that of a standard KiSV RNA, suggesting that it has lost some viral sequences. The oligonucleotide fingerprints of KiLV and VL30 RNAs are distinct from each other and from those reported for other murine leukemia virus RNAs.
Linear unintegrated Kirsten murine sarcoma virus DNA synthesized after acute infection of NIH/3T3 cells or by detergent-disrupted virions, was studied by restriction enzyme cleavage and agarose gel electrophoresis. Labelled DNA (cDNA) synthesized by reverse transcription of a virion RNA template was used to detect viral DNA sequences by filter hybridization. The sites of cleavage for eleven enzymes were located on the genome. Hybridization studies using a cDNA probe specific for the 3' end of the genome defined the orientation of the physical map with respect to virion RNA and identified terminally redundant sequences on the genome. Further evidence for terminal redundancy was obtained by restriction mapping of linear and circular viral DNA, where the duplication was shown to be 0.34 x 10(6) (500 base pairs) in length and in a tandem orientation. Circular viral DNA was found predominantly in the nucleus of acutely infected cells and it existed in two major size classes. The larger size class represented an exact circularization of linear DNA (with no other sequence permutation) whilst in the smaller DNA species one of the terminally redundant sequences was absent.
Two-dimensional fingerprinting of RNase T(1)-derived oligonucleotides of the two individual RNA segments of the Nodavirus black beetle virus indicates that each RNA species possesses a distinct nucleotide sequence. Species 1 RNA has a genome complexity of approximately 3,000 nucleotides, and species 2 RNA is composed of approximately 1,500 nucleotides. Submolar amounts of oligonucleotides apparently derived from a third virus-specific RNA were also detected in black beetle virus RNA preparations.
Clonally derived stocks of defective-interfering (DI) influenza virus prepared by chick embryo fibroblast (CEF) cells were all deficient in genomic RNAs 1, 2 and 3 but had different patterns of subgenomic RNAs. A single passage at high multiplicity in L cells altered the pattern of genomic RNAs independently of the subgenomic species, while in BHK cells the opposite situation prevailed. Therefore, there is no simple relationship in DI influenza virus between the loss of genomic RNA segments and the presence of subgenomic RNAs.
A total of 11 distinct oligonucleotide fingerprints were obtained in studies of the ribonucleic acids of 13 isolates of infectious bronchitis virus. Different serotypes had distinct fingerprints, but so did varieties within a serotype, allowing a greater degree of strain differentiation than was previously possible. Some conclusions can be drawn from the fingerprints concerning theories of origin and spread of infectious bronchitis virus.
Neoplastic transformation by C-type retroviruses requires synthesis of a DNA copy (the provirus) of the RNA genome and its integration into the host cell DNA. We have previously shown that interferon (IFN) can stably prevent transformation of murine fibroblasts by the Kirsten strain of murine sarcoma virus (KiMSV), a murine leukaemia virus (MLV). A series of cell clones (IFN clones), isolated in the presence of IFN (10(4) U ml-1) from cultures of NIH-3T3 cells which had been treated with IFN, and then infected with KiMSV (KiMLV) in conditions where every cell was infected, were shown to be phenotypically untransformed. These untransformed cells did not produce virus or contain rescuable KiMSV. However, cells isolated using an identical procedure, but in the absence of IFN, were uniformly transformed and all produced KiMSV (KiMLV) or contained rescuable KiMSV. It was concluded that IFN either prevents synthesis or integration of the provirus, or else that in the presence of IFN the provirus is integrated such that it is not expressed. We now show that five representative clones contain no detectable KiMSV proviral DNA, and also that the initial stages of infection by KiMSV (KiMLV) are inhibited by IFN treatment. IFN seems to act before integration, preventing either the synthesis or the integration of proviral DNA.
The M protein of avian, but not human, strains of influenza A viruses is synthesized in infected chicken erythrocytes. In dual infections an avian strain complemented the human virus and both the human and avian M proteins were expressed.
Starting with cloned NIH 3T3 mouse cells we have isolated a series of related lines infected with the Kirsten murine sarcoma/leukaemia (MSV/MLV) virus complex. These lines exhibit all three possible infected cell phenotopes: (i) transformed MSV/MLV producers; (ii) non-transformed MLV producers; (iii) transformed non-producers. We have also selected non-transformed revertants from one of the non-producer clones. This series of lines allows the study of the expression of the virus genome against a constant background of cellular gene expression. We have further characterized the lines with regard to anchorage dependence of growth, tumorigenicity and the presence of a rescuable sarcoma genome. The non-producer clones are uniform in their transformed properties. The revertants contain rescuable sarcoma virus, biologically indistinguishable from the original transforming virus, implying that the reversion is due to a change in cellular rather than viurs genetic information.
A Drosophila melanogaster cell line has been examined for the presence of retrovirus particles. When these cells were disrupted and analysed on sucrose density gradients a subcellular fraction with a density of 1.22 g/ml was found to possess endogenous DNA polymerase activity and could catalyse polymerization of deoxynucleotide triphosphates in response to added template primers. The latter activity had the cation and template primer responses expected for reverse transcriptase. A high mol. wt. polyadenylic acid-containing RNA was also purified from this fraction and could be dissociated by heat treatment into 30 to 35S and smaller species. Electron microscopy revealed the presence of torroidal forms reminiscent of intracytoplasmic A-type retrovirus particles within the Drosophila cells. Similar forms were found associated with the subcellular fraction of 1.22g/ml. We concluded that our D. melanogaster cell line contains retroviruses similar, but not identical, to the A-type particles previously described in mammalian and avian cells.
Explore the source record for details and available documents.
Total nucleic acids prepared from a number of murine retroviruses have been shown to contain virus-specific DNA in addition to genomic RNA. This virus-specific DNA has been shown to be at least partially double stranded and to be present within the virus core particle. The DNA isolated from the virus is greatly enriched in virus-specific DNA relative to that from virus infected cells.
Chicken erythrocytes can be infected by the fowl plague (Rostock) strain (FP/R) of influenza type A, Newcastle disease virus (NDV), and Semliki Forest virus (SFV). Only NDV and SFV produced infectious progeny, albeit at low levels. Infection by FP/R was monitored by de novo synthesis of viral proteins, and the proteins synthesized could be identified by comparison with infected chicken fibroblast cells. FP/R synthesized far greater amounts of viral protein than did NDV or SFV.
The H/N and F1 glycoproteins responsible for hemagglutinin/neuraminidase (H/N) activity and fusion (F1) activity were purified from several Newcastle disease virus strains and used to produce antisera. These antisera can be used to clearly distinguish the virus strains by a number of techniques including radioimmunoassay, and so provide a means of classifying new virus isolates. The variations detected between strains are not related to field virulence.
Explore the source record for details and available documents.
Spontaneous production of endogenous xenotropic viruses by clones of New Zealand Black (NZB) embryo cells occurs at a constant level even after several cell transfers. Foci of cell alteration occur spontaneously in some of the clonal lines after 6 to 10 passages. The amount of virus generated does not correlate with spontaneous transformation.. of these NZB cells nor of cells from NIH Swiss or BALB/c mice. The data demonstrate an intracellular regulation of xenotropic virus expression which remains stable over several cell generations and differs from that controlling cell transformation