Publications

phosphonoformate inhibits reverse transcriptase.	the new antiviral substance phosphonoformate (pfa) has been tested in a cell-free system for its effect on reverse transcriptases from an avian retrovirus (avian myeloblastosis virus, amv) and from mammalian retroviruses (rauscher leukaemia virus, rmulv; bovine leukaemia virus; baboon endogenous virus; simian sarcoma virus; visna virus). the observed inhibitory effect of pfa has been compared with that of a structurally related substance, phosphonoacetate (paa). phosphonoformate, at a concentrat ...	1979	94344
translation by escherichia coli ribosomes of alfalfa mosaic virus rna 4 can be initiated at two sites on the monocistronic message.	substantial evidence is provided to corroborate our previous finding that escherichia coli ribosomes recognize two binding sites on the 5' end of alfalfa mosaic virus (amv) rna 4 [for a preliminary report see castel, a., kraal, b., kerklaan, p. r. m., klok, j., and bosch, l. (1977) proc. natl acad. sci. u.s.a. 74, 5509--5513]. translation can start at either site using acphe-trna or fmet-rna as initiator and takes place in the same reading frame along the monocistronic mrna. the size and composi ...	1979	389629
influence of a few coat protein subunits on the base-paired structure of 3'-terminal fragments of rna 4 of alfalfa mosaic virus.	in contrast to expectation (srinivasan, s. and jaspars, e.m.j. (1978) biochim. biophys. acta 520, 237-241) differentiated thermal melting profiles and fluorescence measurements show that the coat protein of alfalfa mosaic virus has a negligible effect on the base-paired structure of isolated 3'-terminal fragments (length about 90 nucleotides) of the coat protein messenger rna (rna 4) of this virus.	1979	427173
energetics of the thermal transitions of rna 1 and rna 4 of alfalfa-mosaic virus in the presence and absence of coat protein.		1979	456342
sequence homology at the 3'-ends of alfalfa mosaic virus rnas.		1979	499559
the primary structure of the coat protein of alfalfa mosaic virus strain vru. a hypothesis on the occurrence of two conformations in the assembly of the protein shell.	the complete primary structure of the coat protein of strain vru of alfalfa mosaic virus (amv) is reported. the strain is morphologically different from all other amv strains as it contains large amounts of unusually long virus particles. this is caused by structural differences in the coat protein chain. the amino acid sequence has mainly been established by the characterization of peptides obtained after cleavage with cyanogen bromide and digestion with trypsin, chymotrypsin, thermolysin or st ...	1979	520317
nucleotide sequence of the 3'-noncoding region of alfalfa mosaic virus rna 4 and its homology with the genomic rnas.	a 226-nucleotide fragment was derived from alfalfa mosaic virus rna 4 (almv rna 4), the subgenomic messenger for viral coat protein, and its sequence was deduced by in vitro labeling with polynucleotide kinase and application of rna sequencing techniques. the fragment contains the 3'-terminal 45 nucleotides of the coat protein cistron and the complete 3'-noncoding region of 182 nucleotides. the total length of rna 4 was calculated to be 881 nucleotides. almv rnas 1, 2 and 3 were elongated with a ...	1979	537914
endonuclease activity of purified rna-directed dna polymerase from avian myeloblastosis virus.	highly purified preparations of rna-directed dna polymerase from avian myeloblastosis virus (amv) contain a mn2+-activated endonuclease activity capable of nicking supercoiled dna. this endonuclease activity co-sediments in glycerol gradients with the alphabeta form of amv dna polymerase, and co-chromatographs with dna polymerase activity on deae-cellulose, phosphocellulose, and heparin-sepharose. it is also present in amv alphabeta-dna polymerase purified by electrophoresis through nondenaturin ...	1979	83998
3'-terminal nucleotide sequence of alfalfa mosaic virus rna 4.	the sequence of the 3'-terminal 91 nucleotides of alfalfa mosaic virus rna 4, the messenger for the viral coat protein, has been elucidated. a fragment containing the 3' terminus of the rna was obtained by mild digestion with rnase t1. the primary structure of the fragment was deduced by labeling it in vitro at its 5' terminus and application of rna sequencing techniques. the sequence is completely extracistronic and is believed to contain the binding sites for the viral coat protein and replica ...	1979	108677
formation of ribosome-rna initiation complexes with alfalfa mosaic virus rna 4 and rna 3.	rna 4 of alfalfa mosaic virus (amv) is a monocistronic messenger for the coat protein. we have determined the sequence of the 40 +/- 2 nucleotides in rna 4 that were protected in the initiation complex formed with wheat germ 80 s ribosomes from digestion by t1 or pancreatic ribonucleases. the aug coat protein initiation codon was near the middle of this protected region. we have found two ribosome-binding sites in rna 3. the principal one, near the 5' end, is the initiation site for the major tr ...	1979	114984
purification of viral proteins from avian sarcoma virus qv2.	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 aga ...	1979	115857
specificity of in vitro reconstitution of bromegrass mosaic virus.	bromegrass mosaic virus (bmv) rna was allowed to compete with yeast trna or alfalfa mosaic virus (amv) rna for in vitro encapsidation by bmv protein. various proportions of 32p-labeled foreign rnas were added to a reassembly mixture (bmv protein: bmv rna, 4:1) and the reassembly products were observed by analytical and rate-zonal sedimentation, and the rna contents of the nucleocapsids were examined by gel electrophoresis. incubation of bmv protein with trna alone produced 56 s particles contain ...	1979	18627894
replication of alfalfa mosaic virus rna: evidence for a soluble replicase in healthy and infected tobacco leaves.	soluble rna-dependent rna polymerases from healthy and alfalfa mosaic virus (amv)-infected leaves were purified more than 400-fold from the 100,000g supernatant of leaf homogenates, using ammonium sulfate precipitation, sephadex g-100 filtration, and chromatography on deae sephadex a25 and p11-phosphocellulose. the deae-chromatography step eliminated host poly(u)polymerase-like activity, cellular rnases, and endogenous rna, yielding a typical rna-dependent rna polymerase ("deae-enzyme") which wa ...	1980	18631630
activation of the genome of alfalfa mosaic virus is enhanced by the presence of the coat protein on all three genome parts.	the same amount of coat protein stimulates the infectivity of alfalfa mosaic virus rna more when added to the three genome rnas at once than when preincubated with one or two genome rnas separately before the inoculum is completed. this suggests that the coat protein activates the genome by interacting with all three parts of it. it could not be demonstrated that infectivity is absolutely dependent on this multiple activation because of the possible exchange of protein between rna molecules in t ...	1980	18631668
synthesis and characterization of dna complementary to carnation mottle virus rna.	dna complementary to carnation mottle virus-rna (carmv rna) was synthesized using the reverse transcriptase of avian myeloblastosis virus (amv) as enzyme, and an hydrolysate of calf thymus dna as primer. after purification steps that included self-annealing and hydroxyapatite chromatography, the dna transcript was more than 99% sensitive to s1 nuclease and hybridized to at least 92% of the carmv-rna sequences, but not to heterologous rna. therefore, the purified transcript was single stranded an ...	1980	18631672
limited sequence variation in the leader sequence of rna 4 from several strains of alfalfa mosaic virus.	the sequences of the 5'-noncoding regions of rna 4 of seven strains of alfalfa mosaic virus were compared. in each case, the coat protein cistron was preceded by a leader sequence of 39 nucleotides (including the initiator codon). at position 26, an a-, g-, or u-residue was found. otherwise the leader sequences are identical.	1980	18631714
cell-free translation of exogenous mrna in extracts from dry pea primary axes.	extracts from the primary axes of dry pea (pisum sativum l.) seeds are able to perform an initiation-dependent translation of exogenous mrna. sds polyacrylamide gel electrophoresis of the products synthesized under direction of alfalfa mosaic virus rna (amv-rna) and tobacco mosaic virus rna (tmv-rna) shows that the fidelity of translation in this pea system is at least as high as in a wheat embryo cell-free protein synthesizing system. the endogenous messengers are also efficiently translated in ...	1980	24311079
enzymatic activities associated with avian and murine retroviral dna polymerases. catalysis of and active site involvement in pyrophosphate exchange and pyrophosphorolysis reactions.	reverse transcriptase isolated from avian myeloblastosis virus (amv) and rauscher murine leukemia virus (rlv) were examined for their ability to catalyze polymerization, ribonuclease h, pyrophosphate exchange, and pyrophosphorolysis reactions. a detailed characterization and a study of requirements for the expression of pyrophosphate exchange and pyrophosphorolysis reactions indicated that a variety of rna and dna template-primers supported these catalytic reactions. furthermore, hydrogen bondin ...	1980	6153389
reactivity of reverse transcriptase toward (s4u,u)n copolymers and spin-labeled nucleic acid lattices.	spin-labeled copolymers of 4-thiouridine and uridine (ls4u,u)n] that contain various amounts of spin label (l) were synthesized by either (i) chemical alkylation of the 4-thiouridine-uridine copolymers (s4u,u)n prepared by copolymerizing 4-thiouridine 5'-diphosphate (s4udp) and udp or (ii) copolymerization of spin-labeled s4udp with udp using polynucleotide phosphorylase. the effect of (s4u,u)n and (ls4u,u)n on avian myeloblastosis virus (amv) rna-dependent dna polymerase (rna-dependent dna nucl ...	1980	6159632
genetic structure of avian myeloblastosis virus, released from transformed myeloblasts as a defective virus particle.	chicken myeloblasts transformed by avian myeloblastosis virus (amv) in the absence of nondefective helper virus (termed nonproducer cells) were found to release a defective virus particle (dvp) that contains avian tumor viral gag proteins but lacks envelope glycoprotein and a dna polymerase. nonproducer cells contain a pr76 gag precursor protein and also a protein that is indistinguishable from the pr180 gag-pol protein of nondefective viruses. the rna of the dvp is 7.5 kilobases (kb) long and i ...	1980	6159639
nucleotide sequence of the putative recognition site for coat protein in the rnas of alfalfa mosaic virus and tobacco streak virus.	the sequence of the 3'-terminal 180 and 140 nucleotides of rnas 2 and 3, respectively, of tobacco streak virus (tsv) was deduced by reverse transcription in the presence of a specific primer and chain terminators. homology between the two rnas was found to be restricted to a 3-terminal region of about 45 nucleotides. the data were compared with the sequence of the homologous region of 145 nucleotides occurring at the 3'-termini of the alfalfa mosaic virus (a1mv) rnas, which contains the specific ...	1980	6160470
glycoprotein and protein composition of bovine leukemia virus (blv).	highly purified preparation of bovine leukemia virus (blv) was obtained by the method described in this communication. blv was isolated from cell-free culture medium, harvested from blv-producing cell-line flk. polyacrylamide gel electrophoresis of blv proteins and glycoproteins, in comparison with avian myeloblastosis virus (amv), confirmed high purity of blv preparations. molecular weights of some blv-proteins and glycoproteins were calculated. by employing polyacrylamide gradient 5 to 30% it ...	1980	6265814
target cell specificity of defective avian leukemia viruses: hematopoietic target cells for a given virus type can be infected but not transformed by strains of a different type.	defective avian leukemia viruses of the avian erythroblastosis (aev), avian myelocytomatosis (mc29), and avian myeloblastosis (amv) type induce the proliferation of leukemic cells with properties of erythroblasts, macrophages, and myeloblasts, respectively. their target cells can be separated and have properties of cells of the erythroid (aev) and myeloid lineage (mc29 and amv), respectively. in the present study we have shown that this target cell specificity is not due to the ability of the di ...	1980	6244556
detection of avian oncovirus group-specific antigens by the enzyme-linked immunosorbent assay.	a three-step sandwich enzyme-linked immunosorbent assay was developed for the detection of avian oncovirus group-specific (gs) antigens. the assay procedure was to coat the wells of microtitre plates with hamster anti-gs igg, react with crude or purified antigen and finally with hamster anti-gs igg linked to horseradish peroxidase. the sensitivity was 8 picograms (pg) of input avian myeloblastosis virus (amv) protein, with negligible background. as the elisa takes less than 2 h to perform, large ...	1980	6245172
avian retroviruses that cause carcinoma and leukemia: identification of nucleotide sequences associated with pathogenicity.	avian myelocytomatosis virus (mc29v) is a retrovirus that transforms both fibroblasts and macrophages in culture and induces myelocytomatosis, carcinomas, and sarcomas in birds. previous work identified a sequence of about 1,500 nucleotides (here denoted onc(mcv)) that apparently derived from a normal cellular sequence and that may encode the oncogenic capacity of mc29v. in an effort to further implicate onc(mcv) in tumorigenesis, we used molecular hybridization to examine the distribution of nu ...	1980	6245277
isolation of complementary dna unique to the genome of avian myeloblastosis virus (amv).		1980	6245521
characterization of avian myeloblastosis-associated virus dna intermediates.	the major species of unintegrated linear viral dna identified in chicken embryonic fibroblasts infected with either the avian myeloblastosis-associated viruses (mav-1, mav-2) or the standard avian myeloblastosis virus complex (amv-s) has a mass of 5.3 x 10(6) daltons. an additional minor dna component observed only in amv-s-infected cells has a mass of 4.9 x 10(6) daltons. the unintegrated linear viral dnas and integrated proviruses of mav-1 and mav-2 have been analyzed by digestion with the res ...	1980	6246269
identification of a proviral genome associated with avian myeloblastic leukemia.	we have identified and isolated a presumptive leukemogenic provirus from myeloblasts of a chicken in which leukemia had been induced by avian myeloblastosis virus (amv). leukemic myeloblasts isolated from peripheral blood or from converted yolk sac cultures of various strains of chickens, regardless of the endogenous proviral content or amv pseudotype used for infection, contain an ecori 2.2-megadalton (mdai) and a hindiii 2.6-mdal proviral fragment. a proviral genome flanked by chicken dna sequ ...	1980	6248880
detection of viral markers and incomplete viral genome rescue from asv transformed rodent cells.	two non-virogenic rat cell lines twerc and fr transformed with pr-rsv and fsv, respectively, were analyzed. both these cell lines contained vrna, but only in twerc cells was the major viral polypeptide p27 synthetized. transforming virus can be rescued from both cell lines only after fusing them with chicken fibroblasts preinfected with avian leukosis viruses of subgroup a, c, d, f and both td mutants of pr-rsv-c and b77-c. similarly, virus was rescued in experiments in which qef infected with r ...	1980	6250919
identification of the avian myeloblastosis virus genome. ii. restriction endonuclease analysis of dna from lambda proviral recombinants and leukemic myeoblast clones.	two lambda proviral dna recombinants were characterized with a number of restriction endonucleases. one recombinant contained a complete presumptive avian myeloblastosis virus (amv) provirus flanked by cellular sequences on either side, and the second recombinant contained 85% of a myeloblastosis-associated virus type 1 (mav-1)-like provirus with cellular sequences adjacent to the 5' end of the provirus. comparing the restriction maps for the proviral dnas contained in each lambda hybrid showed ...	1980	6253659
cellular sequences are present in the presumptive avian myeloblastosis virus genome.	ecori restriction endonuclease fragments from a lambda proviral dna hybrid containing the entire presumptive avian myeloblastosis virus (amv) provirus, and from a lambda proviral hybrid containing a partial myeloblastosis-associated virus type 1 (mav-1)-like provirus were compared by heteroduplex analysis. the cloned presumptive amv provirus was also analyzed by electron microscopy, using r-loop formation with purified 35s rna isolated from virions of the standard amv complex. the results indica ...	1980	6254063
expression of endogenous avian myeloblastosis virus information in different chicken cells.	uninfected chicken cells were found to contain endogenous avian myeloblastosis virus (amv)-specific information. different tissues from chicken embryos and chickens expressed different amounts of the amv-specific information. the endogenous amv-related rna was most abundant in bone marrow cells, which contained about 20 copies per cell. about 5 to 10 copies of amv endogenous rna per cell were found in embryonic yolk sac cells and bursa cells. the spleen, muscle, liver, and kidney cells of chicke ...	1980	6255203
intraspecies variability in transmission efficiency of stylet-borne viruses by the pea aphid (acyrthosiphon pisum).	the efficiency of bean yellow mosaic virus (bymv; potyvirus group) tranasmission from pea to pea plants by 36 clones of the pea aphid (acyrthosiphon pisum) was studied. the efficiency of the clones varied; it was not related to the aphid colour form (green, red or yellow) or the origin of the clone (host plant, geographic area). with alfalfa mosaic virus, the virus-vector relationships concerning transmission efficiency were, in general, similar to those found with bymv. the behaviour of the clo ...	1980	6108064
preferential binding of 3'-terminal fragments of alfalfa mosaic virus rna 4 to virions.	3'-terminal fragments present in a partial ribonuclease t1 digest of rna 4 of alfalfa mosaic virus were selectively bound to virions of the same virus by incubation in 10 mm sodium phosphate and 1 mm edta, ph 7.0. the virions with the associated fragments were separated from the remainder of the digest by velocity gradient centrifugation. when the incubation was performed in 27.7 mm na2hpo4 and 6.2 mm citric acid, ph 6.8, plus 10% glycerol, much more, but less specific, binding was obtained. how ...	1980	6778502
phenylglyoxal as a template site-specific reagent for dna and rna polymerases. selective inhibition of initiation.	phenylglyoxal, an arginine-specific reagent, strongly inhibits dna polymerases isolated from eukaryotic, prokaryotic, and rna tumor viral sources as well as escherichia coli rna polymerase. the inhibitory action of phenylglyoxal appears to be due to interference with the template binding function of these enzymes and implies the presence of an arginine residue at the template binding site of these enzymes from diverse sources and suggests that template dependent dna, and perhaps rna polymerases, ...	1980	6985908
recombinant plasmids containing avian vitellogenin structural gene sequences derived from complementary dna.	purified mrna coding for chicken vitellogenin, a precursor of egg yolk proteins, was transcribed to complementary dna (cdnavit) with avian myeloblastosis virus (amv) reverse transcriptase. double-stranded cdna was synthesized with escherichia coli dna polymerase i (fragment a) using the self priming ability of the cdna. following s1 nuclease digestion the double-stranded cdna was inserted into the hind iii site of plasmid pbr322 using the poly(da) . poly(dt) tailing method, and the hybrid molecu ...	1980	6986172
nucleotide sequences at the 5'-termini of the alfalfa mosaic virus rnas and the intercistronic junction in rna 3.	nucleotide sequences at the 5'-termini of the alfalfa mosaic virus genomic rnas and the intercistronic junction in rna 3 were deduced and compared to identify possible common recognition signals for replicating enzymes in the corresponding minus-stranded viral rnas. homology between the 5'-terminal sequences is less than 11 nucleotides and no complementarity with the homologous sequence occurring at the 3'-end of the viral rnas was observed. homology between the 5'-terminus and intercistronic re ...	1980	6927843
[dna polymerase in the microsomal fraction of the myeloblasts of chickens infected with avian myeloblastosis virus].	only one dna polymerase is present in the microsomal fraction of the cells producing amv. chromatographically purified enzyme shows the properties of revertase, that is it transcribes in dna the information encoded in natural rna. the enzyme possesses identical chromatographic characteristics and the same template specificity as the enzyme isolated from pure amv virus. thus the virus enzyme and the cellular dna polymerase from the microsomal fraction cannot be differentiated on the basis of cert ...	1980	7293688
sequence homology at the 3'-termini of the four rnas of alfalfa mosaic virus.		1980	7353626
application of band centrifugation to the study of the assembly of alfalfa mosaic virus.		1980	7357070
complete nucleotide sequence of alfalfa mosaic virus rna 4.	alfalfa mosaic virus rna 4, the subgenomic messenger for viral coat protein, was partially digested with rnase t1 or rnase a and the sequence of a number of fragments was deduced by in vitro labeling with polynucleotide kinase and application of rna sequencing techniques. from overlapping fragments, the complete primary sequence of the 881 nucleotides of rna 4 was constructed: the coding region of 660 nucleotides (not including the initiation and termination codon) is flanked by a 5' noncoding r ...	1980	7433090
complexes of alfalfa mosaic virus rna 4 with one and three coat protein dimers.	rna 4, the subgenomic coat protein messenger of alfalfa mosaic virus, was loaded with small amounts of coat protein in a reaction in which complete virions were the protein donor. in such a reaction the protein subunits attach to the high-affinity binding sites near the 3' end of rna 4 [houwing, c. j., & jaspars, e. m. j. (1978) biochemistry 17, 2927-2933]. at a ratio of up to 13 coat protein subunits to 1 mol of rna 4, complexes with one and three protein dimers, designated complex i and comple ...	1980	7448167
crystallization of alfalfa mosaic virus coat protein as a t = 1 aggregate.		1981	7299819
binding of ribosomes to the 5' leader sequence (n = 258) of rna 3 from alfalfa mosaic virus.	rna 3 of alfalfa mosaic virus (almv) contains information for two genes: near the 5' end an active gene coding for a 35 kd protein and, near the 3' end, a silent gene coding for viral coat protein. we have determined a sequence of 318 nucleotides which contains the potential initiation codon for the 35 kd protein at 258 nucleotides from the 5' end. this long leader sequence can form initiation complexes containing three 80 s ribosomes. a shorter species of rna, corresponding to a molecule of rna ...	1981	7232211
an investigation of the structure of alfalfa mosaic virus by small-angle neutron scattering.		1981	7265211
an electron microscopic investigation of the structure of alfalfa mosaic virus.		1981	7265214
effects of ethylating agents on dna synthesis in vitro: implications for the mechanism of carcinogenesis.	a highly carcinogenic ethylating agent, ethylnitrosourea (enu), and a weakly carcinogenic one, diethylsulfate (des) react with dna to roughly the same extent but des produces about 6 times as many unstable ethylated bases, which are gradually lost spontaneously under physiological conditions. the different rates of loss for the different dna bases have been studied using polydeoxyribonucleotides. spontaneous strand breakage following base loss is slow, lagging more than a week behind base loss a ...	1981	7273319
improved elisa conditions for detection of plant viruses.	clover yellow vein virus (cyvv) and homologous antisera were used to test effects of time and temperature on enzyme-linked immunosorbent assay (elisa) in polystyrene substrate plates. replicated lattice square and youden square experimental designs were used to measure and account for variation in absorption values associated with sample position within polystyrene plates. adsorption of coating antibody to polystyrene was relatively rapid, reaching optimum assay efficiency in 1 h at 5 degrees c ...	1981	7021575
size and genetic content of virus-specific rna in myeloblasts transformed by avian myeloblastosis virus (amv).		1981	6259824
the genome and the intracellular rnas of avian myeloblastosis virus.	avian myeloblastosis virus (amv) is an acute leukemia virus which causes a myeloblastic leukemia in birds and transforms myeloid hematopoietic cells in vitro. we have analyzed rna from amv virions and from amv-transformed producer and nonproducer cells by gel electrophoresis followed by transfer to chemically activated paper and hybridization to several complementary dna (cdna) probes. using a cdna probe specific for amv, we identified two rna species of 7.2 and 2.3 kb, which were present in all ...	1981	6260378
analysis of avian myeloblastosis viral rna and in vitro synthesis of proviral dna.	two virus-specific rna species of 7.5 and 7.0 kilobases have been identified in avian myeloblastosis virus (amv) by denaturing gel electrophoresis and blot hybridization analysis, and they were found to be in a 10:1 ratio. the individual rnas direccted the cell-free synthesis of the 76,000-dalton "gag" protein and the 180,000-dalton "gal-pol" protein, thereby demonstrating 5' sequence homology of approximately 4.9 kilobases between the two species. synthesis of these two precursor proteins by th ...	1981	6264460
cloning a cdna for the pro-alpha 2 chain of human type i collagen.	poly(a)-rna enriched for type i procollagen sequences was isolated from normal human fibroblasts and used as template to synthesize double-stranded cdna with avian myeloblastosis virus (amv) reverse transcriptase. after the ends had been blunted with nuclease s1 and dgmp tails had been added with terminal deoxynucleotidyltransferase, the double-stranded cdna was annealed with pbr322 dna that had previously been cleaved with ecori, blunted with amv reverse transcriptase, and dcmp-tailed with term ...	1981	6267597
differential effects of transforming avian rna tumor viruses on avian macrophages.	functionally differentiated chicken macrophages were derived by in vitro differentiation of embryonic yolk sac cells and were characterized by several macrophage-specific cell markers. uniform, infected, virus-producing cultures were obtained after exposure of these macrophages to avian myoblastosis virus (amv), avian myelocytomatosis virus (mc29), myeloblastosis-associated virus (mav-2), and prague strain of rous sarcoma virus (pr-b rsv). both amv and mc29 induced morphological transformation t ...	1981	6267600
amino acid sequence of p15 from avian myeloblastosis virus complex.	the complete amino acid sequence of the p15 gag protein from avian myeloblastosis virus (amv) complex has been determined by sequential edman degradation of the intact molecule and of peptide fragments generated by limited tryptic cleavage, cleavage with staphylococcal protease, and cyanogen bromide cleavage. amv p15 is a single-chain protein containing 124 amino acids. the charged amino acids tend to be clustered in the primary structure. p15 contains a single cysteine at position 113 which may ...	1981	6268146
terminal uridylyl transferase of vigna unguiculata: purification and characterization of an enzyme catalyzing the addition of a single ump residue to the 3'-end of an rna primer.	an enzyme which catalyzes the addition of a single ump residue from utp to the 3'-end of an rna primer and which is referred to as terminal uridylyl transferase (tut) has been extensively purified from the membrane fraction of vigna unguiculata leaves. the purification procedure involved (i) solubilization by cation depletion (ii) deae-sepharose cl-6b column chromatography (iii) affinity chromatography of poly(u)-sepharose 4b and (iv) glycerol gradient centrifugation. the molecular weight of the ...	1981	6269049
in vitro translation of avian myeloblastosis virus rna.	avian myeloblastosis virus (amv)-infected cells contain two viral mrna's, a genome-sized 34s (7.5-kilobase) mrna and a 21s (2.5-kilobase) subgenomic mrna, which contains the amv-specific sequences (myb sequences). we found that amv virions packaged both the 7.5-kilobase full-length genomic rna and the 2.5-kilobase subgenomic rna. in vitro translation of amv virion rna sized by sucrose density gradient centrifugation yielded 76,000-, 56,000-, 48,500-, 47,000-, and 32,000-dalton products. the 76,0 ...	1981	6270366
vertebrate dnas contain nucleotide sequences related to the transforming gene of avian myeloblastosis virus.	avian myeloblastosis virus contains a continuous sequence of approximately 1,000 nucleotides which may represent a gene (amv) responsible for acute myeloblastic leukemia in chickens. this sequence appears to have been acquired from chicken dna and to be substituted for the envelope gene in the viral genome. we used hybridization probes enriched for the amv sequences and conditions that facilitate annealing of partially homologous nucleotide sequences to show that cellular sequences related to am ...	1981	6275098
electron microscopic characterization of avian myeloblastosis virus rna by the non-protein technique of spreading.	the quantitative analysis of the behaviour of retroviral rna (amv rna) under the conditions of the non-protein technique of electron microscopic visualization on a mono-molecular film of bac was performed. this technique resulted in visualization of intact molecules the mean length of which was 12% larger in comparison with molecules spread by the cytochrome c method. the method was found to be extremely sensitive to the surface properties of the supporting membrane which distinctly affect the s ...	1981	6276235
characterization of an inhibitor of granulocyte/monocyte colony formation in leukemic chicken plasma.	the plasma of chicks with myeloblastic leukemia (induced by avian myeloblastosis virus, amv) contained an inhibitor which blocked colony formation in vitro by marrow cells. it eluted in the second protein peak obtained by sephadex g-200 gel filtration and was found in the diafiltrate following defiltration through a um 10 membrane under acidic conditions. it was not extractable with chloroform, was heat-stable (65 degrees c, 30 min), pronase-sensitive and had a molecular weight less than or equa ...	1981	6165604
properties of the avian viral protein p12.	the avian rna tumour virus structural protein p12 was purified from avian myeloblastosis virus (amv) by nucleic acid affinity chromatography to apparent homogeneity as judged from sds--polyacrylamide gel electrophoresis. a filter binding assay was used for the identification of p12. high concentrations of p12 precipitated nucleic acids out of solution in the absence of mgcl2. binding of p12 to single-stranded nucleic acids protected them from digestion with nucleases and resulted in a hyperchrom ...	1981	6169796
heterogeneous chromatographic behaviour or soluble rna replicase from healthy and virus-infected tobacco leaves: an improvement of the purification methodology.	during purification of soluble rna replicase from healthy and alfalfa mosaic virus-infected tobacco leaves, crude extracts were chromatographed on deae-sephadex a-25, and three rna-dependent rna polymerase activities were obtained; one of these was previously characterized as a true rna replicase, the remaining two were not studied (chifflot et al., 1980, virology 100, 91). we now demonstrate that all of these activities correspond to the same rna replicase, complexed or not to cellular or viral ...	1981	6173393
evidence for the absence of swelling of alfalfa mosaic virions.	the stability of the quaternary structure of bottom and top components of alfalfa mosaic virus (respectively amv-b and amv-ta-t) in the ph range 5.5 to 7.8 and at ionic concentrations of 0.01 and 0.1 m has been investigated using small-angle x-ray scattering and photon correlation spectroscopy. the x-ray scattering curves show no significant changes over the angular range measured (to a resolution of 1 100 a (-1)) under the various solvent conditions; the radius of gyration of amv-ta-t is consta ...	1981	18635037
lack of serological relationship between the 35k nonstructural protein of alfalfa mosaic virus and the corresponding proteins of three other plant viruses with a tripartite genome.	alfalfa mosaic virus rna 3 was translated in the mrna-dependent rabbit reticulocyte cell-free system. the 35k translational protein was partly purified and used to raise antibodies. the antibodies obtained reacted with the 35k protein directed by amv rna 3 but not with the corresponding proteins directed by rnas from three other viruses with a tripartite genome (tobacco streak, cucumber mosaic, and brome mosaic).	1981	18635042
evidence that alfalfa mosaic virus infection starts with three rna-protein complexes.	the tripartite genome of alfalfa mosaic virus (amv) needs to be activated by its coat protein. to establish whether coat protein exerts its role by interacting structurally with one, two, or all three amv-rna species, the infectivity of mixtures of rna-protein complexes with free rnas were studied (smit and jaspars, virology 104, 454-461, 1980). these studies were not fully conclusive since some redistribution of coat protein does occur as soon as rnas are brought into contact with rna-protein c ...	1981	18635065
evidence that rna 4 of alfalfa mosaic virus does not replicate autonomously.	a mutant (tbts7) of alfalfa mosaic virus, the coat protein of which is unable to activate the viral genome (the rna species 1, 2, and 3, which need some coat protein for infectivity) at 30 degrees , can be rescued at this temperature by adding to the inoculum wild-type rna 3 (the genome part that contains the coat protein cistron), but not adding wild-type rna 4 (the subgenomic messenger for the coat protein). unless rna 3 of tbts 7 has a second ts mutation at a site not occurring in rna 4, it m ...	1982	18635120
molecular cloning of the complementary dna copies of the common and cowpea strains of tobacco mosaic virus rna.	complementary dna (cdna) copies of the common (om) and cowpea (cc) strains of tobacco mosaic virus (tmv) rna polyadenylated in vitro have been synthesized with amv reverse transcriptase and oligo (dt)10 as primer. the cdna was converted to a double-stranded form by e. coli dna polymerase i followed by s1 nuclease digestion. the double-stranded cdna copies were cloned in pbr322 at the psti site using the oligo(dc)-oligo(dg) tailing method. with the common strain, several clones containing inserts ...	1982	18635128
capped mrnas with reduced secondary structure can function in extracts from poliovirus-infected cells.	extracts from poliovirus-infected hela cells were used to study ribosome binding of native and denatured reovirus mrnas and translation of capped mrnas with different degrees of secondary structure. here, we demonstrate that ribosomes in extracts from poliovirus-infected cells could form initiation complexes with denatured reovirus mrna, in contrast to their inability to bind native reovirus mrna. furthermore, the capped alfalfa mosaic virus 4 rna, which is most probably devoid of stable seconda ...	1982	14582204
open reading frame in the minus strand of two plus type rna viruses.	: inspection of the nucleotide sequences of the rnas complementary to the coat protein mrnas from two plant viruses with a tripartite genome: alfalfa mosaic virus and brome mosaic virus, showed the presence of open reading frames for 138 and 118 amino acids, respectively. a third virus (cowpea chlorotic mottle virus) from the same family (1) does not show this phenomenon. this suggests that if a protein is coded for by the open reading frames it may be not essential for virus multiplication. alt ...	1982	24317896
reverse transcriptase associated with avian sarcoma-leukosis viruses. i. comparison of intra-virion content of multiple enzyme forms.	the rna-dependent dna polymerase (the reverse transcriptase) was solubilized from three related strains of avian sarcoma virus (asv b77, asv tsla334, and asv qv2) as well as avian myeloblastosis virus (amv) and a chicken endogenous virus (rav-o), by a combination of non-ionic detergent treatment and cscl step-gradient centrifugation, and was subsequently separated into individual enzyme forms by poly(c)-agarose column chromatography. the newly developed two-step method allowed us to purify the t ...	1982	6175623
reverse transcriptase associated with avian sarcoma-leukosis viruses. ii. comparison of subunit structure and catalytic properties.	the three enzyme forms (alpha, alpha beta-, and beta-form) of the rna-dependent dna polymerase (the reverse transcriptase) from three strains of avian sarcoma virus (asv b77, asv tsla334, and asv qv2) and one exogenous (avian myeloblastosis virus (amv)) and one endogenous avian leukosis virus (rous-associated virus type-0 (rav-0) were compared with each other in subunit structure and catalytic properties. despite the gross similarity in the subunit molecular weight (mr(alpha) = 65,000 and mr(bet ...	1982	6175624
differential inhibition of dna polymerase and rnase h activities of the reverse transcriptase by phosphonoformate.	three potential inhibitors of reverse transcriptase activities, phosphonoformate (pf), phosphonoacetate (paa), and ethyl-diethyl phosphonoformate (et-pf), were compared in this study. only pf was found to inhibit the dna polymerase activity of the purified reverse transcriptase of moloney murine leukemia virus (m-mulv) and avian myeloblastosis virus (amv). the degree of dna polymerase inhibition was linear with pf concentration; 50% inhibition was achieved at 10 mum. whereas pf inhibited both th ...	1982	6178013
5-mercaptopolyuridylic acid (mpu), a potent inhibitor of the reverse transcriptase from avian myeloblastosis virus.	the effects of partially thiolated polyuridylic acid (mpu), partially thiolated polycytidylic acid (mpc), and their unmodified counterparts, poly(u) and poly(c), respectively, on the reverse transcriptase of avian myeloblastosis is virus (amv) have been determined, using different template-primers. poly(c) stimulated and mpc inhibited the polymerization reaction catalyzed by the amv reverse transcriptase in the presence of the natural viral template (endogenous rna or purified 70s rna), or with ...	1982	6179137
inhibition of reverse transcriptase activity of avian myeloblastosis virus by pyrophosphate analogues.	several pyrophosphate analogues have been studied for their effects on avian myeloblastosis virus reverse transcriptase and on cellular dna polymerase alpha. examination of structure-activity relationships for these compounds revealed that two acidic groups connected by a short bridge were necessary, but not sufficient, for inhibition of the enzyme activities. foscarnet sodium (trisodium phosphonoformate) was the most potent inhibitor of reverse transcriptase, giving non-competitive inhibition o ...	1982	6179470
inhibition of avian myeloblastosis virus reverse transcriptase and virus inactivation by metal complexes of isonicotinic acid hydrazide.	the cupric and ferric complexes of isonicotinic acid hydrazide (inh) inhibit the dna synthesis catalysed by avian myeloblastosis virus (amv) reverse transcriptase. the inhibition was to the extent of 95% by 50 microm of cupric-inh complex and 55% by 100 microm of ferric-inh complex. these complexes have been found to bind preferentially to the enzyme than to the template-primer. kinetic analysis showed that the cupric-inh complex is a non-competitive inhibitor with respect to dttp. the time cour ...	1982	6185090
effect of acetylated and deacetylated 2-aminofluorene adducts on in vitro dna synthesis.	we have constructed primed phi x174 dna templates containing either acetylated or deacetylated aminofluorene adducts at the c-8 position of guanine. t4 dna polymerase terminates synthesis one nucleotide before the acetylated adducts but incorporates an additional nucleotide opposite the deacetylated guanylaminofluorene. these observations can be explained by the known preferred conformations of the acetylated and deacetylated guanosinylaminofluorene nucleosides--the former favoring the syn confo ...	1982	6185946
studies on the function of the non-primer trnas associated with the 70 s rna of avian myeloblastosis virus.	significant amounts of three trnas are associated with the 70 s rna of avian myeloblastosis virus (amv). the temperatures at which they are half dissociated from the 70 s rna in 50 mm nacl and their respective quantities relative to 35 s rna are: trnaarg, 51 degree c, 1.6; trnalys, 57 degree c, 0.7 and trnatrp, 76 degree c, 1.0. possible functions for the non-primer trnas (trnaarg and trnalys) were evaluated by determining the effect of their thermal dissociation on: (a) conversion of 70 s to 35 ...	1982	6277384
avian myeloblastosis virus transforming gene is related to unique chicken dna regions separated by at least one intervening sequence.	identification of several additional restriction endonuclease sites within the cellular substitution (amv) inserted into the avian myeloblastosis virus proviral genome has permitted us to isolate different regions of the amv sequence. these subsets of the avian myeloblastosis virus transforming gene have been cloned in the plasmid pbr322 and used as hybridization probes to investigate the topology of homologous (proto-amv) normal chicken dna sequences. the results showed that the cellular proto- ...	1982	6283118
acute leukemia viruses e26 and avian myeloblastosis virus have related transformation-specific rna sequences but different genetic structures, gene products, and oncogenic properties.	replication-defective acute leukemia viruses e26 and myeloblastosis virus (amv) cause distinct leukemias although they belong to the same subgroup of oncogenic avian tumor viruses based on shared transformation-specific (onc) rna sequences. e26 causes predominantly erythroblastosis in chicken and in quail, whereas amv induces a myeloid leukemia. however, upon cultivation in vitro for >1 month, a majority of surviving hemopoietic cells of e26-infected animals bear myeloid markers similar to those ...	1982	6285358
immune stimulation of sensitized chicken lymphocytes by avian retrovirus proteins.	peripheral blood lymphocytes of chickens bearing tumours induced by avian sarcoma virus can be specifically stimulated to divide by the crude culture fluids of virus-infected cells. in this communication, we show that relevant antigenic activity apparently resides in each of the internal virus proteins p15 and p27. the ability of infectious culture fluids to be mitogenic for sensitized lymphocytes is greatly reduced following treatment with antibodies specific for either total avian myeloblastos ...	1982	6286858
proton-magnetic-resonance studies on the coat protein of alfalfa mosaic virus.		1982	6290214
organization of chicken dna sequences homologous to the transforming gene of avian myeloblastosis virus. i. restriction enzyme analysis of total dna from normal and leukemic cells.	hybridization probes consisting of cloned dna recombinants which represent different regions of the leukemogenic sequence (amv) from avian myeloblastosis virus were used to carry out a more detailed restriction endonuclease analysis of the homologous sequences (proto-amv) present in normal and leukemic chicken dna. the results show that four large introns interrupt the normal cellular proto-amv sequences and that there is no major rearrangement of these sequences in leukemic myeloblasts.	1982	6292519
a monoclonal antibody with specificity for leukemic cells transformed by defective avian leukemia viruses.	mouse anti-chicken monoclonal antibodies were raised against an avian myeloblastosis virus (amv)-transformed myeloblastic leukemic cell line. one monoclonal antibody, s1-37 (igg2a), reacted with producer and nonproducer myeloblastic leukemia cell lines transformed by amv and by e-26 virus, but it did not react with chicken fibroblasts infected with rav-2, mav-2, mav-1, or rav-7. s1-37 also did not react with normal chicken hemopoietic cells, except for yolk sack macrophages and a small populatio ...	1982	6302112
nucleotide sequence and organization of the transforming region and large terminal redundancies (ltr) of avian myeloblastosis virus (amv).	avian myeloblastosis virus (amv) is a replication-defective acute leukemia virus, requiring a helper virus to provide the viral proteins essential for synthesis of new infectious virus. the genome of the amv has undergone a sequence substitution in which a portion of the region normally coding for the "env" protein has been replaced by chicken cellular sequences. these latter sequences are essential for the transforming activity of the virus. we have determined the complete nucleotide sequence o ...	1982	6302118
protein binding sites in nucleation complexes of alfalfa mosaic virus rna 4.	the subgenomic coat protein messenger rna 4 of alfalfa mosaic virus forms complexes with one and three coat protein dimers, which are designated complexes i and iii, respectively. these complexes were separated, subjected to digestion with ribonuclease t1, and filtered onto millipore filters. phenol extracts of the filters contained specific fragments of rna 4, which were sequenced after electrophoretic separation on nondenaturing and denaturing polyacrylamide gels. complex i yielded only a 68-n ...	1982	6810924
disintegration of retroviruses by chelating agents.	exposure in vitro of various mammalian retroviruses to the chelating agents edta or egta in millimolar concentrations resulted in partial disintegration of viral membranes as measured by accessibility or even release of reverse transcriptase, an internal viral protein, without any other treatment usually required. among the viruses responding to chelators were mammalian type c viruses, primate type d viruses and bovine leukemia virus. the effect was dose-dependent. the avian type c virus amv, ho ...	1982	6816193
studies on the structure of avian myeloblastosis virus (amv) rna. i. factors affecting electron microscopic visualization of amv rna.	factors affecting the visualization of single-stranded (ss) avian myeloblastosis virus (amv) rna by the basic protein film technique under strong denaturation conditions were studied. the basic parameters of the electron microscopic picture of ss rna, involving the visibility, concentration and contour lengths of molecules, were found to be significantly dependent on the (1) quality of denaturing components used for full extension of amv rna molecules and (2) spreading and formation of the surfa ...	1982	6124101
studies on the structure of avian myeloblastosis virus (amv) rna. ii. integrity of the rna in dependence on rna isolation and virus propagation.	while sedimentation analysis revealed no basic changes in the sedimentation characteristics of 60-70 s avian myeloblastosis virus (amv) rna isolated under different conditions from two sources, electron microscopy exhibited differences in the length distributions of this rna. based on the length distribution profiles, phenol extraction showed a higher degradation effect in comparison with direct gradient centrifugation of viral lysates. proteinase k appeared to be a more suitable nuclease inhibi ...	1982	6124106
studies on the structure of avian myeloblastosis virus (amv) rna. iii. electron microscopic definition of secondary structure.	the secondary structure of avian myeloblastosis virus (amv) rna was characterized by electron microscopy under moderately denaturing spreading conditions. under denaturation by aqueous 44% formamide or 77% formamide in the presence of salts, partly stretched rna molecules with measurable double-stranded regions were observed. this approach allowed the localization from 5 to 11 regions of preserved secondary structure on amv rna molecules. topographic analysis revealed a nonrandom occurrence of s ...	1982	6124107
electron microscopic studies on the structure of 60-70s rna of avian myeloblastosis virus.	structural properties of the 60-70s rna complex of avian myeloblastosis virus (amv) were analysed in electron microscope after treatment under a set of non-denaturing, gently and strongly denaturing conditions. by selected denaturing conditions, the significant fraction of 60-70s amv rna molecules revealed partially unfolded structures either in a dimer or a more complex form and in a length corresponding to mol. wt. of 5.6 x 10(6). the typical dimers contained a characteristic central structure ...	1982	6132536
alterations of the conformation of the rnas of alfalfa mosaic virus upon binding of a few coat protein molecules.	structural changes in the single-stranded genome rnas (rnas 1, 2 and 3) and the subgenomic coat protein messenger (rna 4) of alfalfa mosaic virus upon addition of a few coat protein molecules of the virus were investigated by measuring the fluorescent intensity of bound ethidium bromide and by circular dichroism. no effect could be observed in the case of the genome rnas. however, in rna 4, which is of much less complexity than the genome rnas, a reduction of the ethidium bromide binding by 30% ...	1982	7066325
isolation and characterization of retrovirus-like elements from normal human fetuses.	retrovirus-like particles have been isolated from normal fetal human plasma and from different embryonic organs collected from late first-trimester fetuses. the majority of the virus-like particles banded at a density region of of 1.19-1.22 g/ml, although lighter particles having a density of 1.15-1.17 g/ml were observed in some fetal tissues. the particles appeared similar to retroviruses when viewed electron-microscopically. they contained reverse transcriptase (rt) which accepted oligo (dg)-p ...	1982	7129678
translational competition between related virus rna species in cell-free systems.	the competition between the rnas from two tobacco mosaic virus (tmv) strains for translation in rabbit reticulocyte lysate and wheat germ cell-free systems was investigated. the virus translational products were distinguished by the size difference of the i2 polypeptides. the rnas of the two strains were translated simultaneously if added to the translation system together at the beginning of the reaction. each of the tmv rnas could inhibit translation of the other when the reaction was initiate ...	1982	7142974
differential expression of the amv gene in human hematopoietic cells.	total cellular rnas from a variety of fresh and culture-derived human hematopoietic neoplastic cell types at various stages of differentiation and human sarcoma, carcinoma, melanoma, and glioblastoma cell lines were enriched for poly(a)- containing sequences, fractionated by gel electrophoresis, and blot hybridized to a cloned dna probe containing the transforming sequences (v-amv) of avian myeloblastosis virus (amv), a virus known to cause myeloid leukemias in chickens. expression of rna sequen ...	1982	6954533
levels of colony-stimulating and inhibiting activities in chicks with myeloblastic leukemia are related to disease progression.	chicks with myeloblastic leukemia induced by avian myeloblastosis virus (amv) exhibited increased levels of plasma granulocyte/monocyte (gm) colony-stimulating activity (csa). chromatography of plasma from amv-infected chicks revealed that this csa eluted in the first protein peak from a column of sephadex g-200. a second protein peak from the same column contained an inhibitor of gm colony-formation. the presence of the inhibitor and the increased csa was studied during the development of myelo ...	1982	6978259
amphiphilic properties of the avian myeloblastosis virus major glycoprotein, gp 80.	the major glycoprotein (gp 80) from avian myeloblastosis virus (amv) displays significant lipophilic properties, as shown by its strong interactions with acetylated uncharged decylamino agarose in hydrophobic chromatography. in effect, release from binding was achieved only by the added presence of a polarity reducing agent (ethylene glycol) and the strong anionic detergent sodium dodecyl sulfate. the hydrophobic behavior of the glycoprotein, coupled to the high content of hydrophilic carbohydra ...	1983	6323497
structure of the top a-t component of alfalfa mosaic virus. a non-icosahedral virion.	neutron-scattering in combination with quasi-elastic light-scattering and electron microscopy was used to derive a model for the capsid structure of the top a-t component of alfalfa mosaic virus (amv-ta-t). in the electron microscope, amv-ta-t appears as an irregular ellipsoidal particle with apparent dimensions 275 (+/- 31) a x 225 (+/- 22) a. assuming that the particles are monodisperse, model calculations show that the neutron-scattering data are best explained by an oblate ellipsoidal shape ...	1983	6655690
solution scattering study on the structure of alfalfa mosaic virus strain vru.	neutron-scattering with contrast variation has been used to derive a model for the radial distribution of protein and rna in the vru strain of alfalfa mosaic virus. the rna is distributed uniformly throughout the interior of the capsid up to a radius of 65 a and the protein coat extends from 65 to 100 a. it was found necessary to distinguish between two regions within the protein coat: one with mainly hydrophobic amino acids and another with more hydrophylic amino acids. only a very small part o ...	1983	6655691
translational stability of plant viral rnas microinjected into living cells. influence of a 3'-poly(a) segment.	three different alternative structural features have been shown to be present at the 3' terminus of plant viral rnas: (a) a poly(a) track, (b) a trna-like structure, (c) no special structural or sequence characteristic. we have compared the translational stability after injection into frog oocytes of a representative of each type: (a) the small genomic rna (m-rna) of cowpea mosaic virus (cpmv), (b) the subgenomic mrna for coat protein (rna 4) of brome mosaic virus (bmv), (c) the subgenomic mrna ...	1983	6681761
structural analysis of rna subunits from avian myeloblastosis virus (amv).	subgenomic fragments were released from purified 35s amv rna using strongly denaturing conditions of 78% formamide and 3.9 m urea at 53 degrees c. the fragments were characterized by sedimentation and electron microscopic analysis. the presence of five distinct, reproducible size classes of rna molecules with mean lengths 1.79 +/- 0.07 micron, 1.36 +/- 0.09 micron, 1.03 +/- 0.09 micron, 0.7 +/- 0.08 micron, and 0.42 +/- 0.09 micron were demonstrated. analysis of poly(a)+ and poly(a)- rna fragmen ...	1983	6138994
rna-protein interactions in some small plant viruses.	the structure of the three quasi-equivalent protein subunits a, b and c of the spherical, t = 3 southern bean mosaic virus (sbmv) have been carefully built in accordance with a refined electron density map of the complete virus. the lower electron density in the rna portion of the map could not be explicitly interpreted in terms of a preferred rna structure on which some icosahedral symmetry might have been imposed. however, the extremely basic nature of the interior surface of the coat protein ...	1983	6401119