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Biomedical subjects

G Darai

Publications and source records attributed to G Darai.

At least 163 records · Page 9Linked to original sources
PubMed1982

Tree shrew (Tupaia) herpesviruses.

Five Tupaia herpesviruses have been isolated until now: four in our laboratory which were termed THV-2, 3, 4, and 5, whereas THV-1 has been isolated by Melnick and his colleagues. THV-2 was isolated from tumour cell culture of a high-grade malignant lymphoma of a Tupaia, THV-3 was released from a cell culture of another Tupaia lymphoma, THV-4 from a spleen tissue culture of a moribund animal with finely granulated liver cirrhosis, and THV-5 from cultured spleen cells of an apparently healthy tree shrew. THV-1 to 5 were efficiently propagated, plaque-purified and cloned on Tupaia embryonic fibroblasts. The five isolates of Tupaia herpesviruses are easily distinguished from each other by restriction enzyme analysis of their genomes. THV-1 to 4 are highly pathogenic (lethality 100%) for juvenile Tupaias by intravenous inoculation. In contrast, only 25% lethality was found by intraperitoneal administration. THV-1 to 4 can persist as a latent infection in spleens of Tupaias and rabbits, which allows the recovery of infectious virus from cultured spleens of both animals. THV-2 and 3 induced hyperplasia of the thymus of rabbits which developed malignant thymoma in a few cases. The biological properties and genomic size and structure indicate that THV cannot be considered to belong to one of the three existing subfamilies of herpesviruses.

Animals↗
PubMed1982

Analysis of Tupaia herpesvirus proteins by one- and two-dimensional gel electrophoresis.

The polypeptide composition of four Tupaia herpesvirus strains--of which two were isolated from malignant tumors--was analysed by one- and two-dimensional gel analysis. It was found that purified virions of the tree shrew consist of a least 37 viral polypeptides when determined by SDS polyacrylamide gel electrophoresis. The number of viral polypeptides increased to 49 when analysed by the two-dimensional technique with the molecular weights ranging from 12.000 to 230.000. Variations in the viral polypeptide patterns made it possible to differentiate between the different virus isolated even by the one-dimensional method. The two-dimensional technique allows the identification of virus-specific spots among the polypeptides of virus-infected cells. Radiolabeling experiments identified at least five glycoproteins which seem to reside on the surface of the virus envelope. In addition, neutralisation and immunodiffusion tests were performed which revealed cross-reactivities among the tupaia herpesvirus strains. Rabbit anti-tupaia herpesvirus sera did not neutralize other animal or human herpesvirus.

Animals↗
PubMed1981

The plaque-forming factor for mink lung cells present in cytomegalovirus and herpes-zoster virus stocks identified as Mycoplasma hyorhinis.

Previous investigation of the ability of cytomegalovirus and varicella-zoster virus to replicate in a variety of cell lines suggested that both virus types plaqued with high efficiency in mink lung cells. However, many of the virus isolates used appeared to be contaminated with mycoplasma. We now report that the observed cytopathic effect is due to a mycoplasma which grows lytically to high titre in mink lung cells, but is difficult to cultivate in cell-free media. The mycoplasma was plaque-purified and shown to contain DNA with a buoyant density of 1.684 g/ml, with restriction endonuclease patterns identical to the porcine mycoplasma M. hyorhinis. This was confirmed by serological identification.

Animals↗
PubMed1980

Experimental infection and the state of viral latency of adult tupaia with herpes simplex virus type 1 and 2 and infection of juvenile Tupaia with temperature-sensitive mutants of HSV Type 2.

The susceptibility of adult Tupaia Belangeri to infection with herpes simplex virus (HVS) was investigated. Adult animals were inoculated intraperitoneally with HSV type 1 or 2. With the exception of HSV-2, strain HG-52, 10(5)--10(6) PFU of all HSV strains caused lethal infection irrespective of the age of the animals. Infections HSV was recovered from the spinal cord of those animals which had survived infection with a low dose of virus. The DNA of the recovered viruses was compared to the DNA of the inoculated HSV. The viral genome of the recovered HSV was unchanged as judged by analysis of the fragment pattern of the viral DNA's using restriction endonucleases. Animals which had survived the first HSV infection were protected against a second infection even at highly lethal doses of HSV-1 or 2. Juvenile Tupaia survived infection with temperature-sensitive mutants of HSV-2, strain HG-52, which induced protection against a second infection with lethal doses of HSV-1 or 2.

Aging↗
PubMed1980

Human hypothalamus and intestine contain a hydra-neuropeptide.

From human hypothalamus and intestine a substance was isolated which has the same physico-chemical and biological properties as the head activator from hydra. The hypothalamus of an adult man contained activity corresponding to at least 10(8) hydra. An intestine of a 3-month-old human embryo contained approx. 10(5) hydra equivalents and that of a 6-month-old embryo 10(6). A gradual increase in content of head activator during development was also found in rat intestine.

Animals↗
PubMed1980

Physical map of tupaia adenovirus DNA by cleavage with restriction endonucleases and partial denaturation.

The double-stranded DNA of an adenovirus of tupaia (TAV) which has a mol. wt. of 21.5 X 10(6) was analysed as follows: the cleavage sites of restriction endonucleases BamHI, EcoRI, KpnI, SmaI, BstEII, ClaI and HpaI were determined by complete, partial and double digestion followed by gel electrophoretic separation of the resulting fragments. Terminal HpaI fragments were determined by hydrolysing the intact DNA with exonuclease III before restriction enzyme cleavage. Partial denaturation mapping of uncleaved DNA and EcoRI fragments revealed the cleavage sites of EcoRI as well as A + T-rich regions at both termini of the genome.

Adenoviridae↗
PubMed1980

Identification of polypeptides of the tree shrew (Tupaia) adenovirus.

The virion polypeptides of the Tupaia (tree shrew) adenovirus were analyzed by SDS-polyacrylamide slab gel electrophoresis and by isoelectric focusing. The viral proteins from either nonradioactive or 35S-methionine-labeled virions formed distinct patterns of at least 15 polypeptides which were different from those of known human and animal adenoviruses. Two-dimensional analyses revealed the presence of 18 discernible polypeptides.

Adenoviridae↗
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

Mink lung cells: a non-primate cell line highly susceptible for varicella-zoster virus.

Mink lung cells (MvILu) are highly susceptible to varicella-zoster virus (VZV). The titres of cell-free VZV suspensions reached 1.0 x 10(7) p.f.u./ml at 3 days post-infection, with subsequent cell degeneration, if MvILu cells were infected with a multiplicity of infectious virus of 0.01 p.f.u./cell. In contrast, during the same period and under the same conditions the titres of cell-free VZV were 10(2) to 10(3) times lower when grown on human foreskin fibroblasts. A fast and reliable plaque assay and a neutralization test for VZV on MvILU cells, were developed.

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↗