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Biomedical subjects

N F Moore

Publications and source records attributed to N F Moore.

At least 37 records · Page 2Linked to original sources
PubMed1982

The proteins expressed by different isolates of Drosophila C virus.

Isolates of Drosophila C virus (DCV) from Drosophila flies obtained in geographically different regions were adapted to growth in Drosophila tissue culture cells. The viruses, purified from tissue culture cells, were shown to be serologically related to one of the isolates ("O" from Ouarzazate, Morocco). Analysis of the structural proteins by polyacrylamide gel electrophoresis demonstrated differences between the isolates. Labelling intracellular proteins of infected Drosophila melanogaster cells with 35S-methionine at 28 degrees C demonstrated the presence of the virus structural proteins and their immediate precursors. Raising the temperature to 37 degrees C both before and during the pulse period inhibited the processing of the high molecular weight proteins and resulted in a greater "shut-off" of host cell proteins than viral induced proteins. This allowed the precursor proteins to be compared as well as the structural proteins of the different strains. It was possible to clearly distinguish differences between the isolates on the basis of the induced proteins, although limited proteolysis of corresponding proteins showed marked similarities. Hence it is possible to distinguish between different isolates of the "same" small RNA-virus of insects from geographically different regions.

Animals↗
PubMed1982

Two unique RNA species of the nodavirus black beetle virus.

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.

Journal Article↗
PubMed1981

In vivo and in vitro synthesis of the proteins expressed by the RNA of black beetle virus.

Black beetle virus is a small RNA virus with a single capsid protein of molecular weight congruent to 40,000. Two intracellular proteins, a presumed polymerase (molecular weight 110,000) and a protein having a molecular weight slightly greater than the capsid, were observed when infected Drosophila cells were pulsed with 35S-methionine. Viral RNA coded for the synthesis of several major proteins with molecular weights between 110,000 and 38,000 in rabbit reticulocyte lysate. Long chases of the translated products demonstrated processing of capsid protein precursors into capsid protein. Partial proteolysis demonstrated similarities in the proteins synthesised in vitro and in vivo.

Animals↗
PubMed1981

Processing of cricket paralysis virus induced polypeptides in Drosophila cells: production of high molecular weight polypeptides by treatment with iodoacetamide.

Infection of Drosophila cells with Cricket paralysis virus in the presence of Actinomycin D results in virtual complete inhibition of host cell protein synthesis by four hours post-infection. Using 35S-methionine or 14C-amino acids to pulse infected cells three major classes of viral induced proteins can be detected, (A) high molecular weight precursor proteins, (B) viral structural proteins and (C) low molecular weight cleavage products. The large number of high molecular weight proteins found in the infected cells suggests that a multiple cleavage cascade mechanism is partially utilized to produce virus structural proteins. In infected cells, even with short pulses, the largest viral induced protein obtained has a molecular weight of 144,000. However with pretreatment of the infected cells with iodoacetamide before pulsing, two further proteins are obtained with molecular weights of 205,000 and 190,000. Other changes occur in viral protein precursors in the presence of iodoacetamide.

Animals↗
PubMed1981

In vitro translation of cricket paralysis virus RNA.

Cricket paralysis virus RNA acted as a messenger in a translation system and directed incorporation of 35S-methionine into protein. Polyacrylamide gel analysis of the proteins demonstrated the presence of proteins of comparable molecular weight to the viral structural proteins and also potential high molecular weight precursors.

Insect Viruses↗
PubMed1981

The intracellular proteins induced by cricket paralysis virus in Drosophila cells: the effect of protease inhibitors and amino acid analogues.

Treatment of Cricket paralysis virus infected Drosophila cells with iodoacetamide before radiolabelling with 35S-methionine results in the appearance of two high molecular weight polypeptides of approximately equal to 200,000 molecular weight, not apparent in untreated infected cells (17). To attempt to differentiate between the effects of iodoacetamide being attributable to either alteration of initial polyprotein or inhibition of the protease (either cellular or viral) the effects of a spectrum of protease inhibitors were examined. These included aprotinin, leupeptin, pepstatin, elevated zinc concentration, phenyl methyl sulphonyl-fluoride, N-tosyl-L-lysine chloromethyl ketone (TLCK) and N-tosyl-L-phenylalanine chloromethyl ketone (TPCK). TLCK and TPCK both inhibited the cleavage of proteins which demonstrates an inhibition of the protease activity. The introduction of amino acid analogues into the infected cells before pulsing also results in the appearance of higher molecular weight proteins. This could be attributed to alternation of the polyprotein making it nonsusceptible to digestion with pre-existing cellular protease or newly synthesized viral protease. The possibility that the presence of the amino acid analogues results in alteration of a viral coded protease cannot be eliminated.

Animals↗
PubMed1981

Characterization of a Nuclear Polyhedrosis Virus Isolated from Diseased Gonometa podocarpi (Lepidoptera:Lasiocampidae).

Gonometa podocarpi is an important pest of several species of pine in East Africa, and large numbers of trees in plantations in Kenya were partially or completely defoliated by the larval stage of this insect. After the infestation in the Mt. Elgon region, large numbers of dead and moribund larvae were found on the ground. Examination of extracts of these larvae demonstrated the presence of an occluded virus. Electron microscopy of purified sectioned polyhedra demonstrated the presence of virus particles containing from 1 to 12 nucleocapsids. Purification of virus particles from polyhedra was accomplished by using alkali solubilization and sucrose gradient centrifugation. Virus particles contained 15 proteins as determined by polyacrylamide gel electrophoresis. Detergent solubilization of the virus particles released polyhedra containing one major structural protein. Electron microscopy of purified virus particles and nucleocapsids demonstrated them to be similar in structure to previously recorded nuclear polyhedrosis viruses. The viral deoxyribonucleic acid was extracted and spread for electron microscopy and was determined to have a size of approximately 80 x 10 daltons.

Journal Article↗
PubMed1981

Occurrence of antibodies against insect virus proteins in mammals: simple model to differentiate between passive exposure and active virus growth.

Antibodies against an "enterovirus-like" virus of insects, cricket paralysis virus, occur in the sera of domestic animals. When these antibodies were used in combination with the immunoprecipitation of radiolabeled virus proteins from infected Drosophila cells in culture, it could be demonstrated that the animals were exposed to preformed virus.

Animals↗
PubMed1980

Characterization of cricket paralysis virus-induced polypeptides in Drosophila cells.

Cricket paralysis virus purified from Galleria mellonella larvae was shown to be similar to virus purified from Drosophila melanogaster cells. Cricket paralysis virus contained three major structural polypeptides of similar molecular weight (around 30,000), had a buoyant density of 1.344 g/ml, and had a capsid diameter of 27 nm. Twenty virus-induced polypeptides could be detected in CrPV-infected Drosophila cells. Two major polypeptides found in the infected cells corresponded to two structural viral polypeptides (VP1 and VP3), whereas the third major intracellular polypeptide was the apparent precursor of the third viral structural polypeptide (VP2). Three of the primary virus-induced polypeptides had molecular weights of 144,000, 124,000, and 115,000. These and other polypeptides were chased into lower-molecular-weight proteins when excess cold methionine was added after a short [(35)S]methionine pulse. Although cricket paralysis virus has a number of characteristics in common with the mammalian enteroviruses, the extremely fast processing of high-molecular-weight polypeptides into viral proteins seems atypical. Also, no VP4 (8,000 to 10,000 molecular weight) has been found in the virus particles.

Journal Article↗
PubMed1980

Densonucleosis virus structural proteins.

The protein coats of two densonucleosis viruses (types 1 and 2) were examined by a variety of biophysical, biochemical, and serological techniques. The viruses were 24 nm in diameter, contained at least four polypeptides, were remarkably stable to extremes of pH and denaturing agents, and were serologically closely related. The two viruses could, however, be distinguished serologically and by differences in migration of their structural polypeptides. For each virus the "top component" (i.e., the protein coat minus DNA, found occurring naturally in infections) appeared to have a composition identical to that of the coat of the virus and was a more stable structure. Electrometric titration curves of the virus particles and top components demonstrated that the DNA phosphate in densonucleosis virus particles was neutralized by cations other than basic amino acid side chains of the protein coat. Circular dichroism studies showed that there was a conformational difference between the protein coats of top components and virus particles.

Journal Article↗
PubMed1980

Interrelationships of the proteins of two parvoviruses (densonucleosis virus types 1 and 2).

Densonucleosis viruses (types 1 and 2) contain four major structural polypeptides with a total molecular weight in excess of the coding capacity of the DNA. Peptide maps obtained by limited proteolysis of isolated (125)I-labeled proteins of both virus types indicate a common origin of the virus proteins and homology between the different viruses. The structure of densonucleosis virus type 2 and its homologous top component (naturally occurring empty particles) was compared by proteolysis using several proteases and the bifunctional cross-linking reagents dimethylsuberimidate (DMS) and dimethylmalonimidate. Similar susceptibilities of both components with proteases were obtained. The top components alone were accessible to the action of the cross-linking reagent DMS. The lowest molecular weight major structural polypeptide was most resistant to the action of the proteases and DMS.

Electrophoresis, Polyacrylamide Gel↗
PubMed1978

Transmembrane movement and distribution of cholesterol in the membrane of vesicular stomatitis virus.

The transmembrane movement and distribution of cholesterol in the vesicular stomatitis virus membrane were studied by following the depletion of cholesterol from virions to interacting phospholipid vesicles and by exchange of radiolabeled cholesterol between virions and phospholipid-cholesterol vesicles. The kinetics of the cholesterol exchange or depletion reactions revealed the presence of two exponential rates: a rapid rate, dependent on the vesicle to virus ratio, and a slower rate, independent of the vesicle to virus ratio. The kinetics of cholesterol movement could be best interpreted by a model of the virion membrane considered as a two pool system in which approximately 30% of the cholesterol resides in the outer monolayer and approximately 70% in the inner monolayer. The half-time for equilibration of the two pools was calculated to be 4--6 h and was assumed to represent the time required for transmembrane movement of cholesterol across the bilayer. The initial rate of transfer of cholesterol from virus into vesicles increased when vesicle phospholipids contained more unsaturated and shorter chain fatty acids. Furthermore, the transfer of cholesterol appeared to occur by a collisional mechanism requiring membrane-membrane contact. Interaction with lipid vesicles did not significantly affect the integrity of the virion membrane as assessed by the relative inaccessibility of internal proteins to lactoperoxidase-catalyzed iodination and by the small loss of [3H]amino acid labeled protein from the virus.

Cell Line↗
PubMed1978

Interaction of vesicular stomatitis virus with lipid vesicles: depletion of cholesterol and effect on virion membrane fluidity and infectivity.

Interaction with excess unilamellar phosphatidylcholine (PC) vesicles resulted in depletion of as much as 90% of the cholesterol from the membrane of intact vesicular stomatitis (VS) virus. The cholesterol depletion was not significantly influenced by the proteolytic removal of virion glycoprotein spikes, but it was temperature dependent. Cholesterol depletion caused substantial reduction in anisotropy of the VS virion membrane as measured by fluorescence depolarization of the lipophilic probe 1,6-diphenyl-1,3,5-hexatriene; residual adsorbed vesicles represent a significant factor in this apparent increase in virion membrane fluidity. Interaction with PC vesicles resulted in a substantial loss of VS viral infectivity as measured by plating efficiency on L-cell monolayers. Reduction in infectivity appeared to be related to temperature-dependent depletion of virion cholesterol by PC vesicles. Interaction of VS virions with cholesterol-containing PC vesicles resulted in significantly less decline in infectivity, but attempts to restore cholesterol and infectivity to depleted VS virions were unsuccessful. Depletion of virion cholesterol apparently results through collision with PC vesicles rather than movement of cholesterol monomers or micelles through the aqueous phase, because PC vesicle-virion interaction in the presence of cholesterol oxidase did not result in substantial oxidation of translocated cholesterol.

Cholesterol↗