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Biomedical subjects

B Simizu

Publications and source records attributed to B Simizu.

At least 73 records · Page 4Linked to original sources
PubMed1981

Effect of cadmium on Japanese encephalitis virus infection in mice. 1. Acute and single-dose exposure experiment.

When mice were treated with 0.09 mg cadmium chloride (Cd) per mouse once and inoculated i.p. simultaneously with Japanese encephalitis virus (JEV) they showed a significant difference in the incubation time and mortality between the treated and untreated groups in repeated experiments. Cd treatment shortened the incubation time and the mortality increased greater than twice compared with the untreated control. This effect was not observed in the case of intracerebral inoculation of JEV. Effects of Cd on antibody formation in mice were also determined. Animals given a single s.c. dose of Cd were immunized with JE inactivated vaccine once simultaneously. When mice were treated with Cd, they did not show low neutralizing and hemagglutination inhibition activities compared with the control mice. Pretreatment of Cd did not affect any mortality or antibody formation.

Animals↗
PubMed1981

Growth patterns of temperature-sensitive mutants of Western equine encephalitis virus in cultured Aedes albopictus (mosquito) cells.

Several temperature-sensitive (ts) mutants of Western equine encephalitis virus (WEEV) have been isolated previously from persistently infected cultures of mosquito cells and divided into three groups: early passage RNA- mutants, early passage RNA+ mutants and late passage RNA- mutants (Maeda et al., 1979(. The growth patterns of these groups, as well as of several ts mutants isolated after chemical mutagenesis and of wild-type (wt) WEEV, have been compared in BHK cells and in two strains of mosquito cells. The late passage ts mutants grew much better in mosquito cells than either the wt WEEV or the chemically induced mutants. When mosquito cells were co-infected with a late passage mutant (A125) and Wt WEEV, infectious virions of both parental types as well as phenotypically mixed particles were produced. Infection of mosquito cells with WEEV resulted in a slight suppression of host DNA and protein synthesis during the acute stage of the infection (the first 1 or 2 days). Virus growth in a line of cloned mosquito in which WEEV produced a cytopathic infection (c.p.e.) was analysed with the result that the viruses could be divided into two groups: one in which wt WEEV, chemically induced ts mutants and early passage RNA+ mutants all induced maximal c.p.e., and another in which late passage RNA- mutants and one early passage RNA- mutant induced very little c.p.e., but released much more infections virus into the culture fluid. Electron microscopy showed that in these cloned mosquito cells infected with a virus of the first group, large amounts of virus accumulated on or in the plasma membrane.

Aedes↗
PubMed1981

[An inhalation apparatus for respiratory infections in small laboratory animals (author's transl)].

A dynamic inhalation apparatus with following characteristics was deviced for experimental infections in small laboratory animals. Nebulized bacterial aerosols were blown against a stainless steel ball of 15 mm diameter which was located at 31 mm distance from the nebulizer and smaller-particle aerosols were wafted up via air stream of 60 liter per minute introducing into an inhalation chamber. Thus 5.7 to 6.7 micrometers particles in average were homogeneously distributed in the chamber and inhaled by animals to their lungs with little individual variations in number of bacteria. The exhausted air was sterilized through HEPA filter after heated at 300 degrees C for 10 seconds, and negative inside pressure of the apparatus produced by the suction system served as a safeguard against aerosol leak.

Aerosols↗
PubMed1979

Isolation of the structural proteins of western equine encephalitis virus by isoelectric focusing.

Western equine encephalitis virus was disrupted with Triton X-100 and subjected to isoelectric focusing in a sucrose or urea gradient. The two envelope proteins, E1 and E2 were not well separated in a sucrose gradient, while the E1 and E2 proteins were distinguished as two major peaks which focused in a urea gradient at about pH 7.5 and 10, respectively. Isolated E1 protein refocused at pH 6.5 in a sucrose gradient isoelectric focusing column. When Western equine encephalitis virus was treated with Triton X-100 in 0.01 M phosphate buffer (pH6), hemagglutinating E1 protein was solubilized, which isoelectrofocused at pH 6.5. Purified nucleocapsids focused at pH 4 in a sucrose gradient on an isoelectric focusing column. After ribonuclease treatment of the purified nucleocapsid more than 95 per cent of the viral RNA was acid-soluble, and hte nucleocapsid protein isoelectrofocused at about pH 4.

Encephalitis Virus, Western Equine↗
PubMed1977

Maturation defect of a temperature-sensitive mutant of western equine encephalitis virus.

The defective step of a temperature-sensitive mutant of western equine encephalitis virus, which synthesize viral RNA but not mature virus at the restrictive temperature, was studied. Cells infected with the mutant virus at the restrictive temperature synthesized the same intracellular viral RNA as that in wild type infection. Cells infected with the mutant at the restrictive temperature formed three proteins (E1, E2 and C) which migrated to positions identical with those of purified virions and a precursor protein of E2 (PE2). The mutant virus was also able to form cytoplasmic nucleocapsids sedimenting at 140S as in the case of wild type infection. On the other hand, cells infected with the mutant could not induce a significant amount of hemadsorbing ability and the ability induced at the permissive temperature disappeared immediately after shifting up to the restrictive temperature. These results suggested that the mutant virus produced a defective envelope protein responsible for hemagglutination at the restrictive temperature. Owing to the incompleteness of the modification of the cell plasma membrane by the envelope proteins, viral nucleocapsids in the mutant infected cells could not bind to the plasma membrane.

Culture Techniques↗
PubMed1976

Effect of cordycepin on the replication of western equine encephalitis virus.

Cordycepin (3'-deoxyadenosine) inhibited viral RNA synthesis in the replication of western equine encephalitis virus, thereby causing a reduction of virus production. The rate of inhibition of viral RNA synthesis was dependent on drug concentration and the period of treatment with the drug. These results suggest that the virus RNA synthesizing system is sensitive to the drug.

Dactinomycin↗
PubMed1976

Inhibition of cellular DNA synthesis in hamster kidney cells infected with western equine encephalitis virus.

Infection of BHK cells with western equine encephalitis (WEE) virus resulted in rapid inhibition of cellular DNA synthesis. The rate of inhibition of DNA synthesis depended on the multiplicity of infection, and was closely related to virus replication. Cellular DNA synthesis was not inhibited in infected BHK cells that had been irradiated with ultraviolet radiation. These results indicated that a functional viral genome was required for the inhibition of DNA synthesis by WEE virus. The sharp decrease in thymidine incorporation into the acid-insoluble fraction was not due to a change in the intracellular pool of the acid-soluble fraction. Sedimentation analysis in alkaline sucrose gradients was used to show that cellular DNA was not degraded during WEE viirus infection. DNA polymerase activity in infected cells was not significantly reduced.

Cell Line↗
PubMed1975

Morphological and physical properties of a multiploid-forming mutant of Western equine encephalitis virus.

Morphological and physical properties of a multiploid-forming mutant of Western equine encephalitis virus were studied. Electron micrographs of the infected cells showed that most of mutant virions bud from the plasma or vacuolar membrane as a multiploid particle containing a various number of nucleocapsids enclosed with a defined common envelope. The mutant virions contained three polypeptides which migrated to the position identical with those of wild type on discontinuous acrylamide gels. Cells infected with the mutant virus synthesized the same intracellular viral RNA species as was made after infection of wild type. Cytoplasmic nucleocapsids of the mutant sedimented at 140S and contained 42S virion RNA as those of wild type; they were indistinguishable from those of wild type in an electron microscope examination. On the other hand, mutant nucleocapsids isolated from extracellular virions sedimented as heterogeneous particles larger thant 140S and were shown to be pleomorphic and aggregate in electron micrographs. The budding process of this mutant seemed to be modified, so that it might form the multiploid with the alteration of its nucleocapsids.

Animals↗
PubMed1973

Gamma ray-induced small plaque mutants of western equine encephalitis virus.

Small plaque mutants of Western equine encephalitis virus were obtained from the surviving fractions of wild-type virus which was irradiated with gamma rays. The frequency with which small plaque mutants appeared in the surviving fraction increased with the radiation dose. These mutants were not more resistant to radiation than wild-type virus. The growth rate of a mutant, S127, was lower than that of wild-type. Clonally purified mutant virions presented two peaks in a velocity sedimentation profile; peak 1 corresponded to the peak of wild type and peak 2 moved faster than peak 1. Virions of both peaks were infectious and consistently formed small plaques in chicken embryo cells. Virions reisolated from either peak and grown in chicken embryo cells also revealed two peaks in sedimentation analysis. In the electron microscope examination peak 2 proved to consist of giant form particles, each of which contained more than one nucleoid surrounded with a common envelope. Despite this remarkable morphological difference, densities of the wild-type and S127 mutant virions were similar in cesium chloride gradients. The RNAs and proteins of mutant virions could not be distinguished from those of wild type on the basis of size or charge.

Animals↗