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Biomedical subjects

F A Murphy

Publications and source records attributed to F A Murphy.

At least 19 recordsLinked to original sources
PubMed1979

Viruses isolated from reptiles: identification of three new members of the family Rhabdoviridae.

The growth of four viruses isolated from lizards in Brazil (Marco, Chaco, and Timbo viruses) and Australia (Almpiwar virus) was studied in a variety of continuous cell lines of mammalian, reptilian, amphibian, and piscine origin. Although replication was found in certain cell lines derived from the coldblooded species, cytopathic effect (CPE) was absent or minimal and growth was less than or equal to that in mammalian cells. Those observations appear to limit the value of poikilothermic cells for primary isolation of viruses from field-collected, cold-blooded vertebrates or arthropods that feed upon them. The four reptilian viruses were found to be naturally occurring temperature sensitive agents, with optima for growth of approximately 30 degrees C. Electron microscope studies showed three of the viruses (Marco, Chaco, and Timbo) to be new members of the family Rhabdoviridae. Marco virus particles were conically shaped and resembled bovine ephemeral fever virus, and two lyssaviruses (Kotonkan and Obodhiang). Chaco and Timbo viruses were cylindrical viruses resembling other rhabdoviruses with particle lengths longer than the prototype VSV. No serologic relationships were found in cross complement fixation tests between these viruses, Marco virus, and 34 other rhabdoviruses.

Animals↗
PubMed1979

New strain of mouse hepatitis virus as the cause of lethal enteritis in infant mice.

A new strain of mouse hepatitis virus (MHV) was isolated from pooled gut suspensions from an epizootic of lethal enteritis in newborn mice. Negative-contrast electron microscopy showed an abundance of coronavirus particles in the intestinal contents and intestinal epithelium of moribund mice. We found no other virus in the epizootic. Dams seroconverted to MHV polyvalent antigen and to the agent isolated, but did not develop antibodies to other known mouse pathogens. Virus propagated in NCTC-1469 tissue culture produced enteric disease in suckling mice but not fatal diarrhea; the dams of these mice also developed antibodies to MHV and to the isolates. By complement fixation, single radial hemolysis, and quantal neutralization tests, we found the isolates antigenically most closely related to MHV-S, unilaterally related to MHV-JHM, and more distantly related to MHV-1, MHV-3, MHV-A59, and human coronavirus OC-43. We also studied cross-reactions among the murine and human coronaviruses in detail. Tissues of infected newborn mice were examined by light microscopy, thin-section electron microscopy, and frozen-section indirect immunofluorescence, revealing that viral antigen, virus particles, and pathological changes were limited to the intestinal tract. We have designated our isolates as MHV-S/CDC.

Animals↗
PubMed1979

Abortive replication of vaccinia virus in activated rabbit macrophages.

During the course of infection of rabbits with vaccinia virus, macrophages obtained from the peritoneal cavity develop bactericidal activity and the replication of vaccinia virus becomes restricted in these cells. The abortive replication of vaccinia virus in the activated macrophages was characterized in the present study. The virus adsorbed to and was uncoated equally well in macrophages from both normal and infected rabbits. A burst of deoxyribonucleic acid synthesis of comparable magnitude took place 3 to 6 h after infection in both normal and activated macrophages. Although the production of viral antigens, as detected by immunodiffusion and immunofluorescence, was the same in both types of cells, very few virus particles were formed in activated as compared with normal macrophages. We conclude that a block in a late step of the virus replication cycle occurred in the activated macrophages.

Animals↗
PubMed1979

Rhabdoviridae. Report of the Rhabdovirus Study Group, International Committee on Taxonomy of Viruses.

The family Rhabdoviridae comprises approximately 75 viruses infecting vertebrates, invertebrates and plants. The main characteristics of the member viruses are: (i) the viruses infecting vertebrates and invertebrates are bullet-shaped and the viruses infecting plants are usually bacilliform; (ii) the viruses have particle lengths varying from 130 to 380 nm and widths varying from 60 to 95 nm; (iii) the viruses possess unit-membrane envelopes from which protrude spikes 5 to 10 nm long; (iv) the viruses have precisely coiled helical nuecleocapsids with a diameter of approx. 50 nm; (v) most of the viruses which have been studied contain 5 proteins; the prototype, vesicular stomatitis virus, contains proteins designated L (large), G (glycoprotein), N (nucleoprotein), NS (nonstructural) and M (matrix); N or NS is phosphorylated in most members which have been studied; (vi) the viruses contain single-stranded RNA which is transcribed into several messenger RNA species with sizes corresponding to the structural proteins; (vii) the nucleocapsid contains the RNA-dependent RNA polymerase and is infectious; and (viii) many of the viruses produce morphologically distinct defective-interfering (T) particles.

RNA, Viral↗
PubMed1978

Lyssavirus infection of muscle spindles and motor end plates in striated muscle of hamsters.

Immunofluorescent, light, and electron microscopy were used to document lyssavirus infection of muscle spindles and motor end plates. Virus particles were seen in the narrow intercellular space between sensory nerve endings and intrafusal muscle fibers; they were also observed budding from intracellular and plasma membranes of the latter. Involvement of motor nerves and motor end plates could only be demonstrated by electron microscopy. In nature, rabies virus invasion of the peripheral nervous system must involve centripetal spread across these junctions.

Animals↗
PubMed1978

New Minto virus: a new rhabdovirus from ticks in Alaska.

Three strains of a virus were isolated from Haemaphysalis leporis-palustris (Packard) ticks removed from snowshoe hares (Lepus americanus Erxleben) in east central Alaska. We suggest that the virus be named New Minto for the location in which the ticks were collected. Prototype New Minto virus is sensitive to the action of sodium deoxycholate and kills suckling mice by the intracerebral but not intraperitoneal route; weaned mice do not die after intracerebral, intraperitoneal, or subcutaneous inoculation. The virus produces plaque in serially propagated Vero but not in primary Pekin duck embryo cells. By complement-fixation and neutralization tests New Minto is related to Sawgrass Virus, a hitherto ungrouped virus from Florida. The establishment of a Sawgrass group is suggested. In addition, Sawgrass virus was found by electron microscopy to belong to the Family Rhabdoviridae.

Alaska↗
PubMed1977

Effect of surveillance on the number of hysterectomies in the province of Saskatchewan.

In 1972 the College of Physicians and Surgeons of Saskatchewan appointed a committee to study hysterectomies because the Saskatchewan Department of Health had data showing that the annual number of hysterectomies carried out in the province had increased by 72.1 per cent between 1964 and 1971, whereas the number of women over 15 years of age had increased by 7.6 per cent. The committee compiled a list of indications for hysterectomy. Any hysterectomy carried out for one of these reasons was classified as justified, and the remainder as unjustified. Five hospitals were reviewed in 1970 and a further two in 1973. In 1974, all seven hospitals were reviewed again. In these hospitals, the average proportion of unjustified hysterectomies had dropped from 23.7 per cent at the time of the first review to 7.8 per cent in 1974. The total number of hysterectomies in the province dropped by 32.8 per cent between 1970 and 1974.

Adolescent↗
PubMed1977

Anticonvulsant prolongation of survival in adult murine lymphocytic choriomeningitis. I. Drug treatment and virologic studies.

Lymphocytic choriomeningitis virus-induced central nervous system disease is characterized by death during a seizure approximately seven days after intracerebral inoculation. This process is mediated by thymus dependent lymphocytes, sensitized against viral antigens. Various forms of immunosuppressive treatment prevent the seizure death and produce persistently infected survivors. In this study, anticonvulsant treatment (particularly diazepam treatment) of LCM virus infected mice prolonged survival without affecting viral replication, or suppressing immune responsiveness. This prolongation of life did not lead to a reversal of pathologic processes and there were no survivors. However, anticonvulsant treatment permitted study of more advanced stages of the choriomeningitis than has previously been possible.

Animals↗
PubMed1977

Anticonvulsant prolongation of survival in adult murine lymphocytic choriomeningitis. II. Ultrastructural observations of pathogenetic events.

Because previous ultrastructural studies of murine lymphocytic choriomeningitis (LCM) had revealed only mononuclear cell infiltration with no cytopathology of target cells in the choroid plexus, ependyma, and leptomeninges, diazepam treatment was used to prolong survival for characterization of late pathogenetic events. Mice which were treated with diazepam and sacrificed 8, 9, and 10 days after intracerebral inoculation with LCM virus showed an increasing amount of inflammatory infiltration into choroid plexuses, leptomeninges, Virchow-Robin spaces, and ependyma. Mononuclear cells, lymphocytes, and polymorphonuclear (PMN) leukocytes increased in number as compared with terminally infected mice sacrificed 7 days after inoculation. Ultrastructurally, choroidal epithelial cells showed cytopathological changes varying from dilated endoplasmic reticulum through necrosis. Greater numbers of PMN leukocytes, macrophages, and activated macrophages and fewer undifferentiated mononuclear cells were seen in choroid plexuses of the drug-treated survivors. Virions and larger, more numerous arenavirus inclusions were present in choroid plexus and ependyma. Ultrastructurally the leptomeningitis was characterized by large numbers of activated macrophages. Choroidal epithelial necrosis appears to be the in vivo correlate of T-cell-mediated cytotoxicity in vitro.

Animals↗
PubMed1977

The reticuloendothelium as the target in a virus infection. Pichinde virus pathogenesis in two strains of hamsters.

The course of Pichinde virus infection in two strains of hamsters, LVG and MHA, was studied by sequential frozen-section immunofluorescence and light and electron microscopy. The major destructive effects of the infection were in the spleen and liver. In the spleen, primary target cells were macrophages in the marginal zone of the white pulp with subsequent spread into elements of the red pulp. In the liver, there was Kupffer cell and hepatocellular infection. The extent of involvement correlated with the outcome of infection; more extensive and progressive necrosis occurred in the fatally infected MHA than in the LVG strain in which infection was self-limiting. In neither strain of animal was there demonstrable infection of lymphoid cells. Similarly, lesion sites did not have mononuclear inflammatory infiltrations which are characteristic of most viral infections. These findings suggested that, in contrast to the situation in other rodent arenavirus infections, the lesions in these hamsters were probably not consequences of immunopathologic host response but rather were a result of direct viral effects in concert with a genetically determined host susceptibility.

Animals↗
PubMed1977

Identification of Rickettsia rickettsii in a guinea pig model by immunofluorescent and electron microscopic techniques.

Moribund guinea pigs infected with Richettsia rickettsii were examined by necropsy, histology, immunofluorescence, electron microscopy, and serology. Untreated animals died at 9 and 10 days after inoculation. Animals given saline subcutaneously survived from 1 to 4 days longer. Prolonged survival was accompanied by more severe lesions: scrotal necrosis; infarction of ears; and swollen, hemorrhagic footpads, epididymis, and cremaster muscle. Histopathologic examination demonstrated that acute, necrotizing vasculitis, perivascular hemorrhage, and focal necrosis were more extensive. Direct immunofluorescence indicated many more rickettsiae in endothelium and vascular wall of saline recipients. Ultrastructurally, typical rickettsiae were present focally in the cytoplasm of endothelial and vascular smooth muscle cells. Cytopathology in infected and adjacent cells included swelling, mitochondrial enlargement with decrease in matrix density and loss of cristae, and increased pinocytosis. In addition, treated animals had more cytonecrosis, thrombosis, extravascular fibrin deposition, prominent inflammatory cells with polymorphonuclear phagocytosis of rickettsiae, and antibody production.

Animals↗
PubMed1976

Structural proteins of La Crosse virus.

Preparations of La Crosse virus, a member of the California encephalitis group of bunyaviruses, were found to possess three major virion proteins. Two of the proteins were glycosylated (G1 and G2) and were located on the surface of the virus particles. These two glycoproteins were present in equimolar amounts and possessed apparent molecular weights of 120 X 10(3) and 34 X 10(3). Virion nucleocapsids, isolated by a nonionic detergent and salt treatment, contained another major protein, N (molecular weight = 23 X 10(3)). A large, but minor, protein species L (molecular weight = 180 X 10(3)) was also found in virus preparations. The approximate number of protein molecules per virion has been determined. Electron microscopy of purified La Crosse virus indicated that the virus particle (mean diameter, 91 nm) is enveloped and possesses irregular surface projections (length, 10 nm).

Arboviruses↗