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Biomedical subjects

K Munk

Publications and source records attributed to K Munk.

At least 19 recordsLinked to original sources
PubMed1992

Carbohydrate masking of an antigenic epitope of influenza virus haemagglutinin independent of oligosaccharide size.

Comparison of the haemagglutinins (HA) of the pathogenic avian influenza viruses A/FPV/Dutch/27 (H7N7) and A/FPV/Rostock/34 (H7N1) revealed 94.7% nucleotide and 93.8% amino acid sequence homologies. Six of the seven N-glycosidic oligosaccharides of the Rostock HA are at the same positions as the six carbohydrates of the Dutch strain. The additional oligosaccharide side chain of the Rostock strain, which is of the complex type, is attached to asparagine149 in antigenic epitope B. The accessibility of this antigenic epitope has been analysed by using rabbit antisera raised against synthetic peptides comprising amino acids 143-162. The carbohydrates of the HA of the Rostock strain have been modified (i) to truncated cores by expression in insect cells using a baculovirus vector, (ii) to oligomannosidic side chains by growth in the presence of the trimming inhibitor methyldeoxynojirimycin and (iii) to a single N-acetylglucosamine residue by removal of the oligomannosidic sugar with endo-beta-N-acetylglucosaminidase H. Neither the authentic nor the modified oligosaccharides allowed antibody binding, as indicated by enzyme-linked immunosorbent assay (ELISA) and Western blot analyses. Reactivity was observed, however, after complete removal of the carbohydrate from HA of the Rostock strain by digestion with peptide-N-glycosidase F. HA of the Dutch strain was reactive without prior peptide-N-glycosidase F treatment. These results demonstrate that a single N-acetyl-glucosamine at asparagine149 is sufficient to prevent recognition of the peptide epitope.

Amino Acid Sequence↗
PubMed1978

Establishment of a variant cell clone growing at 41 degrees C from embryonic rat and tupaia (tree shrew) fibroblast cells.

Rat and tupaia 41 degrees C temperature variant cell clones were derived from parental embryonic cells, cloned and established in tissue cultures. Both variant cell clones grew permanently at 41 degrees C. The morphology of these cell clones was altered in comparison to the original fibroblast cell clones. The cell biological characterization of the rat and tupaia 41 degrees C temperature variant cell clones showed that both cell clones were stable. After abolishing the selection pressure (incubation at 41 degrees C) for more than 10 further cell passages by incubation at 37 degrees C and then raising the temperature again to 41 degrees C, neither of the cell clones lost their newly acquired property of growing at 41 degrees C. This fact demonstrates that the newly acquired property is certain to be genetically manifest in both cell clones. The modal number of chromosomes of the rat 41 degrees C temperature variant cell clone was increased, and in the case of the tupaia variant cell clone, bimodality was observed. The plating efficiency of both cell clones did not rise significantly in comparison to the parental cells. Neither of the 41 degrees C temperature variant cell clones grew in semi-solid medium.

Animals↗
PubMed1978

Experimental infection of Tupaia belangeri (tree shrews) with herpes simplex virus types 1 and 2.

The susceptibility of Tupaia belangeri (tree shrews, which are primitive prosimian primates) to infection with herpes simplex virus (HSV) and the pathogenesis of HSV in these animals were investigated. Juvenile (28--45 days old) and adult (150 days old) animals were inoculated intravenously, intraperitoneally, or subcutaneously with HSV type 1 or 2 (25--10(5) plaque-forming units per animal). Clinical illness usually appeared in juvenile animals on the second day after inoculation, and the animals died between two and 14 days after inoculation. High titers of infectious HSV were recovered from liver and spleen. The histopathologic examination always showed severe liver changes with numerous necrotic areas. The morphologic events in the liver were designated as herpetic hepatitis. The next most common morphologic findings were encephalitis and fibrosis in the spleen. These results demonstrate the high pathogenicity of HSV types 1 and 2 in juvenile T. belangeri. In contrast, adult animals did not develop acute clinical disease and survived the HSV infection.

Animals↗
PubMed1978

Protection of mice against viral infection by Corynebacterium parvum and Bordetella pertussis.

Mice could be significantly protected against infection with herpes simplex virus (HSV) by i.p. or i.v. injection of killed Corynebacterium parvum 7 days before infection. This protection was seen in inbred strains of mice with a different degree of sensitivity to HSV and after both i.p. and i.v. infection. Resistant mice immunosuppressed by X-irradiation and showing an increased susceptibility to HSV could also be protected by a previous injection of C. parvum. Elevated levels of interferon were demonstrated in the serum of mice injected with C. parvum 5 to 12 days previously. Four different strains of anaerobic coryneforms were compared and only those which were able to induce a systemic activation of the lymphoreticular system (as reflected by splenomegaly) protected against HSV infection. Protection against HSV-infection could also be demonstrated by using killed Bordetella pertussis. C. parvum also protected against Semliki Forest virus infection in two different strains of mice.

Animals↗
PubMed1978

In vitro mitogenic stimulation of murine spleen cells by herpes simplex virus.

Spleen cells of B6 mice not previously immunized were induced to DNA synthesis by supernatants from HSV-infected tissue culture. The stimulatory principle could be passed through a 45-micrometer filter and sedimented at 100,000 x G. It was abolished by UV light, heating at 56 degrees C, and by an anti-HSV serum. The possibility that the observed stimulation was caused by LPS was therefore excluded, and there was a-so no indication of mycoplasma contamination. Partial purification of spleen cells from macrophages resulted in an increased stimulation by HSV. From experiments with nylon columns, anti-theta antibody, and nude mice it was concluded that HSV acted as a B cell mitogen. Strains of both HSV types 1 and 2 were stimulatory for B6 spleen cells. Of nine freshly isolated HSV strains with identical passage history (twice in HEF) four were strongly stimulatory, three showed a moderate stimulation, and two did not stimulate. Spleen cells from A/J and DBA/2 mice were stimulated to the same extent by HSV (WAL) as spleen cells from B6 mice. No viral replication was demonstrable in B6 spleen cell cultures stimulated for DNA synthesis by HSV. Thus our study demonstrates induction of cellular DNA synthesis in B lymphocytes by HSV which is abolished by inactivation of the virus.

Animals↗
PubMed1978

Transformation of skin fibroblast cells of a cystinotic patient by simian virus 40: evidence for an establishment of a permanent cell clone which retains the original metabolism defect.

Human skin fibroblast cells derived from a juvenile patient with nephropathic cystinosis were transformed by simian virus 40. Transformed cell clones were isolated and established in tissue culture. In comparison to the parental cystinotic cells, the newly isolated, transformed cell clones had a higher plating efficiency, a modal chromosome number of 68, grew in soft agar, and showed a nuclear immunofluorescence typical for SV 40-specific tumor (T) antigen. The content of intracellular, unbound cystine in the transformed cell clone was of the same level (6.1 nmol 1/2 cystine/mg protein) as in the parental cystinotic cells (7.4 nmol). Control cells (SV 80 and WI-38) contained normal levels of cystine (0.31 and 0.47 nmol 1/2 cystine/mg protein). The growth characteristics make the transformed cystinotic cell clone suitable for large scale preparation of cellular constituents, i.e. lysosomes which seem to be affected in cystinotic patients.

Adolescent↗
PubMed1978

Differences in susceptibility to herpes simplex virus infection of inbred strains of mice.

Marked differences were observed between the susceptibility of adult C57BL/6 and DBA/2 mice to infection with HSV-1. These differences were seen after various infection schedules but were most marked after i.p. infection. A significant difference between the LD50 after i.p. infection was also observed between LPS-resistant C3H/HeJ and the closely related LPS-sensitive C3HeB/FeJ mice. Injection of LPS significantly increased the LD50 after i.p. infection with HSV in C57BL/6 or C3H/HeJ mice but not in C3HeB/FeJ mice. In vitro pretreatment with LPS was necessary to demonstrate replication of HSV in mouse spleen-cell cultures. Such replication could be demonstrated in cultures of DBA/2 and C3HeB/FeJ but not in C57BL/6 or C3H/HeJ mice.

Animals↗
PubMed1978

Immunological studies of hsv-infection of resistant and susceptible inbred strains of mice.

DBA/2 mice were found to be quite susceptible to infection with herpes simplex virus (HSV) while C57BL/6 mice and F1 hybrids between the 2 strains were relatively resistant. This difference was most marked after ip infection, but could also be demonstrated after intracerebral, intravenous or subcutaneous infection. In both strains the LD50 was considerably higher after ip infection than after iv infection, and a dose of X-irradiation was required to kill the mice by sc infection. A/J and BALB/c mice were equally susceptible after ip infection but differed significantly after iv infection. C57BL/6 were made susceptible to ip infection by immunosuppression with antilymphocyte serum or cyclophosphamide. LPS, when given simultaneously with HSV also markedly increased the susceptibility of C57BL/6 mice. Susceptible DBA/2 mice which surrvived a low dose of HSV ip were not immune but C57BL/6 mice surviving a high dose were immune against rechallenge. Both strains of mice could be protected by an apathogenic, tissue-culture-attenuated strain of HSV against infection with the virulent strain. They could also be protected by iv injection of a sublethal dose against a lethal ip infection.

Animals↗
PubMed1977

Detection of SV40 T antigen with labelled antibodies: radioimmunoassay and autoradiography.

SV40 T antigen, partially purified from SV80, a human cell line, has been used to develop a sensitive solid phase radioimmunoassay. In this assay SV40 T antigen was immobilized on microtiter plates, reacted with hamster anti-SV40 T antibody and subsequently with 14C-labelled anti-hamster IgG. The test detected approximately 20 ng of partially purified SV40 T antigen and is rapid and more convenient than the complement fixing reaction. An immunoautoradiographic method which permits the determination of the cellular localization of SV40 T antigen and which is possibly more sensitive than the indirect immunofluorescence method is also described.

Antibodies, Anti-Idiotypic↗
PubMed1977

Activation of an endogenous C-type RNA virus in rat embryo cells after transformation by herpes simplex virus types 1 and 2.

Reverse transcriptase activity was detected in the supernatants of rat embryo fibroblast cell cultures transformed by HSV types 1 and 2 at either the sub-optimal temperature of 20 degrees C or the supra-optimal temperature of 42 degrees C. Rat cells clones which had been transformed at 20 degrees C contained higher levels of C-type virus DNA polymerase than did cell clones which had been transformed at 42 degrees C. Syncytia formation typical for C-type RNA viruses occurred at passages higher than 24. The activation of endogenous C-type RNA viruses was independent of the virus and transformation method used.

Animals↗