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J T SYVERTON

Publications and source records attributed to J T SYVERTON.

At least 19 recordsLinked to original sources
PubMed1961

Pathogenicity for suckling mice of Coxsackie viruses adapted to human amnion cells.

Continuous passages in primary human amnion cell cultures of Coxsackie prototype viruses A-9, A-10, A-11, A-13, A-14, A-15, A-18, B-1, B-2, B-4, and B-5 increased the titers, hastened and enhanced cytopathic effect, and in varying degrees caused loss of virulence for newborn mice. Only B-3 behaved differently in that neither adaptation to cells in vitro nor attenuation with respect to the original animal host could be observed. Types A-15, B-1, B-2, and B-5 slowly regained virulence when passed in mice after high concentration passages in amnion cells whereas all other viruses reverted to their original virulence after only 1 or 2 passages in the animal host. When these strains, however, were purified by cloning procedures, they too showed markedly increased stability. In all stages of attenuation, viruses multiplied extensively in vivo as could be shown by titration in amnion cell cultures. It is suggested that a genetic mechanism is operative leading to virus populations in which the majority of the particles is qualitatively changed.

Amnion↗
PubMed1961

The mammalian cell-virus relationship. VI. Sustained infection of HeLa cells by Coxsackie B3 virus and effect on superinfection.

Sustained infection of HeLa cells by Coxsackie B3 virus, dependent on presence of viral inhibitor in culture medium, was achieved. Persistent treatment of carrier cultures with anti-Coxsackie B3 hyperimmune monkey serum eventually eliminated virus from carrier cultures indicating that a lysogenic virus-cell relationship was not operative. Free virus was produced continuously by carrier cultures despite washing and neutralization with antiserum to eliminate free virus temporarily. In carrier cultures, about 1.5 to 1.9 plaque-forming units of virus per cell were cell-associated; approximately 6 per cent of this cell-associated virus was not neutralizable by antiserum. In growth medium containing anti-B3 antibody, cells from carrier cultures formed colonies as efficiently as cells from B3-cured cultures. Assays of carrier cultures for infectious centers indicated that less than 1 per cent of cells produced free infectious virus. The Coxsackie B3 virus-carrier state appeared to represent surface residence of B3 virus on the majority of carrier cells with restriction of productive infection to a small proportion of the population. Coxsackie B3 carrier HeLa cultures, unlike control cultures, were not destroyed by challenge with Coxsackie B1, B3, or B5 viruses. The B3 carrier state did not interfere with superinfection by herpes, vaccinia, and types 1 to 3 polioviruses. In contrast to parental or B3-cured lines, B3-carrier HeLa cultures superinfected with Coxsackie B1 virus produced no significant virus, and cultures superinfected with B5 viruses produced new virus to a limited extent only. Specific interference with Coxsackie virus superinfection by the B3-carrier state of HeLa cells was shown to be attributable to failure of attachment in the instance of Coxsackie B1 virus, and failure of penetration and/or eclipse in the instance of B5 virus. The interfering effect was circumvented successfully by superinfection of carrier cells with ribonucleic acid extracted from Coxsackie B1 and B5 viruses.

Enterovirus↗
PubMed1961

Enteroviruses.

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Enterovirus↗
PubMed1960

Enteroviral ribonucleic acid. I. Recovery from virus and assimilation by cells.

A relatively sensitive and adequately reproducible assay of infectious enteroviral RNA was obtained by exposing calf serum-grown HeLa cells to RNA suspended in 2 M magnesium sulfate solution. Highly purified enteroviral preparations yielded RNA exhibiting more than 0.1 per cent of the infectivity of whole original virus and infectivity regressed linearly with dilution. Radioisotope experiments with P(32)-labeled RNA and spectrophotometric studies demonstrated that Gierer-Schramm phenol extraction permits almost quantitative recovery of high molecular weight RNA from poliovirus. Intact chromatography-purified type 2 poliovirus in the analytical ultracentrifuge showed a sharp boundary and a sedimentation coefficient of S(20, w) = 147 +/- 5S. Phenol-extracted poliovirus RNA exhibited a heterodisperse sedimentation pattern with a large proportion of homogeneous, rapidly sedimenting material having a coefficient of S(20, w) = 37 +/- 2S. Although the bulk of extracted poliovirus RNA as measured by radiophosphorus labeling was not taken up by cells, the infectious fraction of RNA was adsorbed rapidly by HeLa-cell or L strain mouse fibroblast monolayers, indicating a possible dissimilarity between the bulk of extracted virus RNA and a relatively small fraction responsible for infectivity. Enhancement of poliovirus RNA infectivity for HeLa cells by high ionic-strength magnesium sulfate solution appeared due partly to an effect of hypertonicity on cells, and partly to an effect of high-concentration divalent cation on RNA itself, but not to enhancement of adsorption. Poliovirus RNA adsorbed by HeLa cells apparently was rapidly received within the cells since it became quickly insusceptible to ribonuclease. Heterologous nucleic acids and degradation products to the level of oligoribonucleotides inhibited infectivity of poliovirus RNA for HeLa cells. This inhibitory activity appeared due to intermolecular complexing, since exposure of cells to heterologous RNA immediately before or after exposure to virus RNA failed to reduce infectivity. Ultraviolet absorption spectra demonstrated that the RNA within intact poliovirus is more hypochromic (and thus more extensively hydrogen-bonded) than is the same RNA isolated by phenol extraction, and suspended in 0.02 M phosphate buffer.

HeLa Cells↗
PubMed1960

Enteroviral ribonucleic acid. II. Biological, physical, and chemical studies.

Chromatographic behavior of whole type 1 poliovirus and phenol-extracted viral RNA on diethylaminoethyl cellulose columns, as revealed by assay of plaque-forming capacity, indicated that infectious RNA had surface properties markedly different from those of the intact virus. Infectious RNA of type 1 poliovirus and Coxsackie B1 virus was relatively resistant to heat inactivation as compared to intact virus. Kinetics of inactivation at elevated temperatures were multi-hit in character. The structure of infectious enterovirus RNA was investigated by treatment with chemical inactivating agents. Urea and guanidine as hydrogen bond-disrupting agents, and mercaptoethanol and thioglycolate as disulfide bond-disrupting agents, and combinations of these did not destroy RNA infectivity whereas hydrogen bond-disrupting treatment inactivated intact virus rapidly. RNA infectivity was not reduced by chloroform extraction alone, or by octanol extraction alone, but was reduced by chloroform-octanol extraction which failed to depolymerize RNA to an extent detectable by ultracentrifugal analysis. Infectivity of type 1 poliovirus and Coxsackie B1 virus RNA was destroyed in accordance with first order kinetics by very dilute solutions of pancreatic ribonuclease, and by purified snake venom phosphodiesterase, but not at all by bacterial alkaline phosphatase. Inactivation by venom diesterase was not accelerated by prior treatment of RNA with bacterial alkaline phosphatase. These results indicated that infectivity of enteroviral RNA resided in a single stranded structure, that a single break of a phosphodiester bond anywhere along the structure was sufficient to destroy infectivity, and that infectivity did not require a terminal phosphate group. Hydroxylamine, but not other carbonyl reagents, rapidly destroyed infectivity of intact type 1 poliovirus viral RNA without depolymerization of RNA-detectable by behavior in the analytical ultracentrifuge. With S(35)-methionine-labeled poliovirus a very small fraction of radioactivity remained in RNA preparations following phenol extraction. No evidence could be obtained to indicate that infectious enteroviral RNA was composed of subunits. RNA extracted with phenol during the course of infection of HeLa cells with type 1 poliovirus resembled RNA obtained from purified whole virus with respect to heat inactivation, hydroxylamine inactivation, chromatographic separation, susceptibility to protein denaturing agents, and ability to infect productively both naturally susceptible HeLa cells and naturally insusceptible L strain mouse cells. Intracellular production of infectious RNA paralleled intracellular maturation of whole virus and preceded it by a very short interval.

Animals↗
PubMed1959

The mammalian cell-virus relationship. IV. Infection of naturally insusceptible cells with enterovirus ribonucleic acid.

Ribonucleic acid extracted with phenol from Type 1 poliovirus, Coxsackie A-9, Coxsackie B-1, and ECHO 8 viruses infected non-primate cells and animals insusceptible to whole virus as such. Viral RNA was proved infectious for insusceptible cells in test systems of established cell lines, primary monolayer cultures, Maitland type cultures, and living animals inoculated intracerebrally. Cells of rabbit, swine, mouse, guinea pig, chicken, and hamster were infected. Each virus produced was identical with the virus donating RNA, in (a) neutralization by homotypic antiserum, (b) resistance to ribonuclease treatment, and (c) failure to be adsorbed or replicated by nonprimate cells, even of the strain producing the virus from RNA. Produced virus was adsorbed and replicated by susceptible primate cells as usual. Virus in RNA-infected cell cultures was produced in a single cycle unaccompanied by overt cytopathic effect on non-primate cells or disease of intracerebrally inoculated animals. By drastic elution of infective poliovirus associated with rabbit cells exposed to massive inocula of intact virus, intact poliovirus was shown to infect insusceptible non-primate cells to produce progeny indistinguishable from the parent virus population. Under these conditions, infection was accomplished by about 10 virus plaque-forming units per billion inoculated.

Animals↗