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Biomedical subjects

L Berthiaume

Publications and source records attributed to L Berthiaume.

At least 37 records · Page 2Linked to original sources
PubMed1988

Electron microscopic evidence for bridges between bovine respiratory syncytial virus particles.

Electron microscopic examination of ultrathin sections of a continuous cell line of ovine kidney (OK) origin, infected by bovine respiratory syncytial virus (BRSV), revealed the presence of well defined bridges between virus particles. This is the first report of this novel structure. Observation of ultrathin sections of human RSV Long strain also grown on OK cells did not show inter-particle bridges and therefore suggested that this structure could be specific to BRSV. The biological significance of these bridges is not clear at this time; a possibility is that the bridges are formed by the fusion protein of BRSV which is known to cause cell fusion. Besides the structural implications, the importance is in relation to purification strategies for this virus, which must now take into account that most of the viral particles occur in large aggregates.

Animals↗
PubMed1986

Identification of the glycoproteins of lymphocystis disease virus (LDV) of fish.

Analysis of highly purified fish Lymphocystis Disease Virus (LDV), strain Leetown NFH, by three different methods, namely periodic Acid Schiff reaction, radiolabelling with tritiated fucose and N-acetyl-D-glucosamine and staining with three lectins, indicated that ten glycoproteins were associated with the virus structure. Six of them were detected by all of the three methods, three by both radiolabelling and lectin staining but only one by the lectin technique. Localization of these glycoproteins at the surface or inside the virion is discussed.

Animals↗
PubMed1985

An enteric coronavirus of the rabbit: detection by immunoelectron microscopy and identification of structural polypeptides.

The immunoelectron microscopy (IEM) technique has been used for the detection of a rabbit enteric coronavirus (RECV). Immune serum was prepared in guinea pigs; the viral antigen used for the immunization procedure was obtained from the caecum of a sick rabbit, concentrated by centrifugation and purified on Percoll gradient. In order to identify the viral particles used in the immunization procedure, the protein pattern of the particles was determined by electrophoresis and compared with the pattern of other known coronaviruses. Analysis of structural polypeptides of the purified viral particles revealed a pattern similar to that reported for other coronaviruses. These polypeptides cross reacted with two other coronavirus specific immune sera (IBV and TGE). IEM assay of fecal samples collected from healthy and sick rabbits showed the presence of immune aggregates in specimens from both sick and healthy rabbits. Those aggregates contained viral particles sharing morphological characteristics with other coronaviruses. Furthermore, IEM assay was shown to be more sensitive than a direct EM procedure to detect coronavirus particles in rabbit feces. This assay also allowed the detection of a larger number of chronic carriers.

Animals↗
PubMed1985

New actinophage species.

All actinophages of known morphology are tailed. From 305 phages surveyed, 4 belong to the Myoviridae family, 283 to the Siphoviridae, and 18 to the Podoviridae (two morphotypes each). 58 of 139 actinophages described since 1976 are classified in this report, and the earlier phage descriptions are updated. Nine new species and type viruses are proposed, bringing the total number of actinophage species to 29 and the number of bacterial host genera to 15.

Actinomycetales↗
PubMed1984

Morphology and ultrastructure of Lymphocystis disease virus, a fish iridovirus, grown in tissue culture.

The morphology and the ultrastructure of the Lymphocystis disease virus (LDV) strain Leetown , a fish iridovirus , was studied by electron microscopy. The virus was grown on bluegill fry (BF-2) cells at 21 degrees. LDV showed an icosahedral shape by ultrathin sections and negative staining, with a diameter of about 200 nm. The shell of the virion seemed to be composed of two unitary membranes with a total diameter of 16 nm. The outer membrane demonstrated swelling in negative staining, exhibiting a central core and the presence of globular subunits at its external surface organized in geometrical arrays of 60 and 90 degrees. Glutaraldehyde fixation preserved very effectively the icosahedral structure with the subunits remaining invisible. The internal structure of the virions was composed of osmiophilic threads or granules of 6 to 8 nm in diameter surrounded by an amorphous material of 10 to 20 nm in thickness. External filaments were observed at the surface of the particles in ultrathin sections, giving the appearance of a halo surrounding the shell. In negative staining these filaments were rarely observed; in one virus preparation, they appeared in bundles.

Animals↗
PubMed1982

Mammalian cells contain a DNA-recombining activity that can be dissociated from topoisomerase activity.

The role of the topoisomerase enzyme in DNA recombination was investigated by extracting chromosomal deoxyribonucleoproteins from a variety of cultured mammalian cells and assaying for the formation of recombinant DNA structures. Although each of the crude deoxyribonucleoprotein preparations contained topoisomerase activity, they did not all contain DNA-recombining activity. A distinct, perhaps novel, enzyme may therefore promote DNA recombination in these cell-free systems.

Animals↗
PubMed1982

Expression of virus-like particles in normal and transformed gerbil cells.

Three types of virus-like particles (VLP) were observed in three of seven gerbil cell lines. One of these cultures was in a non-transformed state and contained R and C-type VLP, while the two others began to express R-type or intracisternal A-type VLP only after spontaneous transformation. These particles seem to be endogenous to the gerbil but do not appear to be directly involved in cell transformation.

Animals↗
PubMed1982

Plaque assay of bluegill virus using a methylcellulose overlay.

The EFDL strain of Bluegill virus (BGV) has been titrated in BF-2 cells by the plaque method using 1% methylcellulose overlay. Visible plaques, formed 7 days postinfection, ranged in diameter from 0.5 to 1 mm. Dose-response experiments indicated that a single particle initiated the formation of a plaque. The titration of BGV by this new plaque method provided an accurate technique for the determination of virus concentration.

Animals↗
PubMed1982

Electron microscopic study of bluegill virus.

Bluegill virus (BGV) grown in BF-2 cells was studied by negative staining and ultrathin sections of infected cells. Although BGV resembles bunyaviruses in gross physical appearance, it differs from this group in several important aspects. Thus, BGV cannot be classified as a member of the Bunyaviridae family and could be a representative of a novel family of enveloped RNA viruses.

Animals↗
PubMed1981

Comparison of three electron microscopy techniques for the detection of human rotaviruses.

Rotavirus detection by direct electron microscopy was compared with direct and indirect immune electron microscopy techniques. The latter two approaches permitted the enumeration of 25 and 103 times more rotaviruses respectively, than direct electron microscopy. Also, 70% and 90% of the virus particles were aggregated by direct and indirect immune electron microscopy techniques respectively, thus facilitating their detection.

Antibodies, Viral↗
PubMed1981

Purification of lymphocystis disease virus (LDV) grown in tissue culture. Evidences for the presence of two types of viral particles.

Lymphocystis disease virus was highly purified from host cells by precipitation with PEG-6000 and isopycnic centrifugation in a metrizamide gradient. Metrizamide gradient centrifugation produce two distinct bands at equilibrium. As calculated from reconstruction experiments, only 4 and 0.3% respectively of the host DNA and the host proteins were recovered at the position of the bands. The final recovery of infectivity was about 41%. Electron microscopy of the bands showed two types of particles: small and dense particles measuring 100-150 nm and lymphocystis virions that measured about 300-350 nm in diameter.

Animals↗
PubMed1979

Influenza viruses in birds: rapid identification by counterimmunoelectrophoresis.

Counterimmunoelectrophoresis with an antiserum raised in rabbits against the M protein of the avian N virus proved to be particularly useful for large-scale identification of influenza A virus isolates. Of a total of 231 hemagglutinating agents isolated from 1,656 rectal swabs collected from shore and open-country birds, 158 could be identified as influenza A viruses by counterimmunoelectrophoresis, and 75 were serologically related to Newcastle disease virus by hemagglutination inhibition with an antiserum to Newcastle disease virus. Two isolates contained a mixture of influenza A virus and Newcastle disease virus; although the Newcastle disease virus virus particles outnumbered the influenza A virus particles in a ratio of 1,000:1, as seen by electron microscopy, the latter could be readily detected by counterimmunoelectrophoresis. This type of assay appears to be of potential use for epidemiological surveillance of influenza virus isolated from humans and animals. It combines specificity, sensitivity, and simplicity.

Animals↗
PubMed1978

Morphological and quantitative study of spirochetes in the feces of normal and infected SPF pigs during the incubation period of swine dysentery.

Spirochetes found in feces of normal and infected pigs during the eight days preceding the onset of the clinical signs of swine dysentery have been studied using electron and phase contrast microscopy. According to their dimensions, diameter, length and pitch, three morphological groups have been described: small, intermediate and large spirochetes. On the basis of their axial filaments arrangement, eight types have been observed. Compared to the control pigs, there was no increase in the total number of spirochetes in infected pigs, except at day 6 before the onset of clinical signs. However, infected pigs have shown a wide spectrum of different morphological types of spirochetes in comparison to control, uninfected pigs, which showed only the type "1-2-1" spirochete of axial filaments arrangement. This last type was predominant in infected swine during the entire incubation period as compared to other spirochete types described.

Animals↗