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Biomedical subjects

S A Stohlman

Publications and source records attributed to S A Stohlman.

At least 145 records · Page 8Linked to original sources
PubMed1981

Comparative analysis of RNA genomes of mouse hepatitis viruses.

The RNA genomes of various murine hepatitis virus (MHV) strains were studied by T1-oligonucleotide fingerprinting analysis with regard to their structure and sequence relationship. It was found that the MHV particles contained only positive-stranded 60S RNA which had a "cap" structure at its 5' end. No negative-stranded RNA was found. It was also shown that most of the MHV strains had diverged quite extensively in their genetic sequences. However, MHV-3, a hepatotropic strain, and A59, a nonpathogenic strain, were found to have very similar oligonucleotide fingerprinting patterns. Yet, each of them contained two to four specific oligonucleotides. The MHV-3-specific oligonucleotides were conserved in almost all of the hepatotropic MHV strains studied. In contrast, two of the A59-specific oligonucleotides were absent from the genomes of all hepatotropic strains. These findings suggest that these unique oligonucleotides might be localized at the genetic region(s) associated with viral pathogenicity or other biological properties of the virus. Comparison of viral structural proteins also suggests that MHV-3 and A59 are more closely related than other MHV strains. The significance of these findings is discussed.

Animals↗
PubMed1981

Mouse hepatitis virus A59: mRNA structure and genetic localization of the sequence divergence from hepatotropic strain MHV-3.

The composition and structure of the mouse hepatitis virus (MHV)-specific RNA in actinomycin D-treated, infected L-2 cells were studied. SEven virus-specific RNA species with molecular weights of 0.6 X 10(6), 0.9 X 10(6), 1.2 X 10(6), 1.5 X 10(6), 3.0 X 10(6), 4.0 X 10(6), and 5.4 X 10(6) (equivalent to the viral genome) were detected. T1 oligonucleotide fingerprinting studies suggested that the sequences of each RNA species were totally included within the next large RNa species. The oligonucleotides of each RNA species were mapped on the 60S RNA genome of the virus. Each RNA species contained the oligonucleotides starting from the 3' end of the genome and extending continuously for various lengths in the 3' leads to 5' direction. All of the viral RNA species contained a polyadenylate stretch of 100 to 130 nucleotides and probably identical sequences immediately next to the polyadenylate. These data suggested that the virus-specific RNAs are mRNA's and have a stairlike structure similar to that of infectious bronchitis virus, an avian coronavirus. A proposal is presented, based on the mRNA structure, for the designation of the genes on the MHV genome. Using this proposal, the sequence differences between A59, a weakly pathogenic strain, and MHV-3, a strongly hepatotropic strain, were localized primarily in mRNA's 1 and 3, corresponding t genes A and C.

Animals↗
PubMed1981

Chronic central nervous system demyelination in mice after JHM virus infection.

The pathogenesis of murine hepatitis virus, strain JHM, was studied in 6- and 12-week-old C57/BL mice. There was 100% mortality in the 6-week-old mice after intracerebral inoculation. The lesions were characterized by necrotizing encephalomyelitis, without demyelination. Intracerebral inoculation of 12-week-old animals, however, resulted in no morbidity or mortality. The 12-week-old animals showed transient virus replication in the brain, spinal cord, and liver, which was cleared by day 14. Histologic examination showed evidence of ongoing demyelination, concomitant remyelination, and hydrocephalus ex vacuo. Although viral antigen was demonstrated by immunofluorescence in the central nervous system of these animals, no infectious virus was recovered, and immunosuppression regimens did not potentiate the disease.

Animals↗
PubMed1980

Remyelination following viral-induced demyelination: ferric ion-ferrocyanide staining of nodes of Ranvier within the CNS.

Ferric ion-ferrocyanide (Fe-FeCN) staining was used to stain nodes of Ranvier in remyelinating central nervous system (CNS) axons following viral-induced demyelination. As at normal nodes, Fe-FeCN staining was observed on the cytoplasmic surface of the nodal axolemma of remyelinated fibers. These fibers were identified on the basis of inappropriately short internode lengths and thin myelin sheaths. Thus, newly formed nodes along remyelinated CNS axons recapitulate at least one normal nodal membrane property.

Animals↗
PubMed1980

Host-induced virus modification of murine hepatitis virus: changes in thermal stability.

Serial tissue culture passage of two cold-sensitive mutants of murine hepatitis virus altered the thermal stability of one mutant. This phenomenon occurred in only one of the continuous cell lines tested and was reversible by multiple passages in a cell line that does not alter thermal stability. The effect was cumulative with passage and was segregated from the cold-sensitive marker.

Animals↗
PubMed1980

Attempts to demonstrate virus in amyotrophic lateral sclerosis.

Neurons were isolated from the brain and spinal cord of five patients with clinical and pathologic evidence of amyotrophic lateral sclerosis (ALS). The following studies were carried out to detect the presence of infectious virus. Homogenates of isolated neurons were passaged in several cell lines at different temperatures; isolated neurons were cultured; and supernatant fluids were passaged on the cell lines. Neurons were also cocultivated and fused with continuous cell lines and subsequently passaged; isolated neurons were examined by electronmicroscopy and immunofluorescent techniques, using sera from ALS patients. No evidence of virus was found by these methods.

Amyotrophic Lateral Sclerosis↗
PubMed1980

Resistance to fatal central nervous system disease by mouse hepatitis virus, strain JHM. II. Adherent cell-mediated protection.

Resistance of SJL/J mice to intracranial inoculation with the JHM strain of mouse hepatitis, a coronavirus, is dependent upon the age of the animals at inoculation. Animals 12 weeks of age or older are resistant, whereas those 6 weeks or younger are uniformly susceptible to viral infection. Spleen cells or thioglycolate elicited peritoneal exudate cells can transfer resistance from 12-week-old to 6-week-old recipients. Removal of the adherent cells from either spleen or peritoneal cells ablated protection. Adherent cells from 12-week-old mice were protective even after depletion of Ia- and Thy-1-bearing cells. Antiviral antibody, thioglycolate injection into 6-week-old animals, and nylon wool-purified T cells were ineffective in mediating resistance. Adherent cells transferred 4 days before virus challenge, but not after challenge, were protective. Thus, there is an age-related change in SJL mice that protects from acute central nervous system disease, which may be due to maturation of a specialized adherent cell population.

Aging↗
PubMed1979

Phosphoproteins of murine hepatitis viruses.

Four strains of the coronavirus murine hepatitis virus were examined for the presence of phosphorylated proteins. The nucleocapsid protein was determined to contain phosphate covalently linked to serine but not to threonine residues. The nucleocapsid protein was the only phosphorylated protein detected in these strains of murine hepatitis virus.

Capsid↗
PubMed1978

Stability of neurotropic mouse hepatitis virus (JHM strain) during chronic infection of neuroblastoma cells.

A line of mouse neuroblastoma cells which was chronically infected with the neurotropic strain (JHM) of MHV, a member of the coronavirus group, was established. These cells, designated NJ, exhibited typical MHV cytopathic effects (CPE) at all passage levels along with the continual production of infectious virus. Most cells were positive for viral antigen by immunoflourescence. Viral particles consistent with the morphology of MHV were found by electron microscopy. The uninfected neuroblastoma cell line did not contain a detectable population of cells resistant to JHM, and persistence did not elicit the production of interferon. No plaque morphology or temperature sensitive mutants were selected for in the NJ culture, and we were unable to detect the presence of either a defective or defective interfering virus population. The addition of low concentration antiviral antibody modulated the infection to a carrier culture with viral antigen in the cytoplasm of the cells, but no infectious virus was produced, and the cells lacked both surface viral antigen and CPE. Possible mechanisms of viral persistence in vitro are discussed.

Animals↗
PubMed1978

RNA of mouse hepatitis virus.

The RNA of mouse hepatitis virus, a coronavirus, was isolated from the virus released early in the infection and analyzed by sucrose gradient sedimentation and electrophoresis. It was found to consist of a piece of single-stranded RNA of about 60S. Its molecular weight was estimated to be 5.4 X 10(6) by electrophoresis in methylmercury-agarose gels. At least one third of the RNA contained polyadenylated sequences. It is, therefore, probably positive stranded. The virus harvested late in the infection contained, in addition to 60S, some 30 to 50S RNA that are possibly degradation products of the 60S RNA. No difference in the electrophoretic behavior could be detected between the RNA isolated from a pathogenic (JHM) and a nonpathogenic (A59) strain.

Molecular Weight↗
PubMed1978

Dengue viral antigens in host cell membranes.

Membranes from type 2 dengue virus (DEN-2) infected BHK cells, when used as immunogen, elicit antibodies detectable by complement fixation, hemagglutination inhibition and plaque reduction neutralization tests with suckling-mouse-brain-derived DEN-antigens. Membrane fractions from infected cells separated by sucrose density gradient centrifugation were employed as antigen in serological tests with anti-DEN-2 infected suckling mouse brain hyperimmune mouse serum and hyperimmune mouse ascitic fluid. Antigen (s) capable of fixing complement were associated with all membrane fractions, including the plasma membrane, whereas antigen capable of reacting with antihemagglutinin was largely confined to the two membrane bands consisting of (1) a mixture of rough and smooth endoplasmic reticulum (2) predominantly rough endoplasmic reticulum.

Antigens, Viral↗
PubMed1976

Isolation of the dengue virus envelope glycoprotein from membranes of infected cells by concanavalin A affinity chromatography.

The membranes isolated from type 2 dengue virus-infected BHK-21/15 cells contain three glycosylated virus-specified proteins; one corresponds to the virion envelope glycoprotein, V-3, whereas the other two are nonstructural virus-specified proteins, NV-2 and NV-3. A combination of two nonionic detergents, Nonidet P-40 and Triton X-305, solubilized greater than or equal to 80% of the membrane-bound protein and the majority of the type 2 dengue virus complement-fixing antigens. The soluble material was adsorbed by concanavalin A-Sepharose in the presence of the nonionic detergents, which were subsequently removed by washing with deoxycholate-containing buffer. Finally, the bound glycoprotein was eluted by the addition of alpha-methyl glucopyranoside. V-3 was the only virus-specified protein in the alpha-methyl glucopyranoside eluate. The V-3-containing fraction did not cross-react with antisera against other selected Flaviviruses in the complement fixation tests. The V-3 contained in the isolated fraction differed from the parent membrane-bound V-3 in two interesting, and as yet unexplained, ways: (i) it exhibited hemagglutinating activity similar to that of the infectious virus, but (ii) it did not block the action of neutralizing antibody.

Antigens, Viral↗
PubMed1975

Dengue virus-induced modifications of host cell membranes.

Enzymatic markers and electron microscopy were utilized to determine the cellular origin of the membrane types isolated from type 2 dengue virus-infected BHK cells by discontinuous sucrose gradient centrifugation. The results showed an apparent separation of plasma membrane, smooth and rough endoplasmic reticulum with increasing density. Virus-induced protein and RNA synthesis, as indicated by the incorporation of radiolabled precursors, was localized on the rough endoplasmic reticulum. Glycosylation, measured by the incorporation of radiolabeled glucosamine into membrane-associated proteins, was most active in the bands of intermediate and smooth endoplasmic reticulum. Polyacrylamide gel electrophoresis of isolated membrane bands, radiolabeled in the presence of actinomycin D, after pulse inhibition by cycloheximide, revealed seven virus-specific proteins associated with all membrane fractions. Viral structural protein V-3, and nonstructural proteins NV-3 and NV-2, increased with decreasing density, whereas NV-5 and NV-4 remained constant. The viral capsid protein V-2 was depleted in the intermediate and smooth endoplasmic reticulum, suggesting that these membranes may serve as the sites for viral maturation. NV-3 was the most prominent virus-specified protein found in the plasma membrane.

Cell Line↗