PubMed Health⌕ Search

Biomedical subjects

D W Verwoerd

Publications and source records attributed to D W Verwoerd.

At least 37 records · Page 2Linked to original sources
PubMed1983

Isolation and preliminary characterization of the jaagsiekte retrovirus (JSRV).

Jaagsiekte, or ovine pulmonary adenomatosis, is caused by a recently discovered retrovirus. The virus cannot be cultivated in vitro at present, but a procedure is described for the isolation and purification of small amounts in the form of immune complexes with IgA from affected lungs. The virion was shown to possess a 70S RNA genome which can be transcribed by an endogenous reverse transcriptase. Nine size from 94 000 to 25 000 daltons, were found in purified preparations. Using neutralization of the viral reverse transcriptase and an enzyme immunoassay as criteria, no serological relationship could be demonstrated to representatives of type B, C and C oncoviruses, or to bovine leukemia virus, maedi-visna virus of sheep or caprine arthritis-encephalitis virus.

Animals↗
PubMed1983

The morphology and morphogenesis of jaagsiekte retrovirus (JSRV).

Jaagsiekte retrovirus ( JSRV ) was recently shown to be the aetiological agent of jaasiekte (ovine pulmonary adenomatosis). The morphogenesis of JSRV was studied in jaagsiekte tumour tissue. Intracytoplasmic particles, often associated with centrioles, were found in tumour cells. JSRV budded from tumour cells with a complete core which appeared to mature during the budding process. Extracellular particles were found in the alveolar lumen. Immature extracellular particles were rare. Mature extracellular JSRV was membrane-bound and had a slightly eccentric nucleoid with an electron-dense perinucleoidal space. In negatively stained preparations of JSRV the envelope was covered with spikes. JSRV is morphologically distinct from all known retroviruses.

Animals↗
PubMed1980

On the aetiology of Jaagsiekte.

A summary is given of the results obtained in experimental transmission of jaagsiekte by means transplantation of cell cultures. Evidence is also presented of transformation as the mechanism of oncogenesis and possibility of a viral aetiology is discussed briefly.

Animals↗
PubMed1980

Aetiology of jaagsiekte: transmission by means of subcellular fractions and evidence for the involvement of a retrovirus.

Jaagsiekte (ovine pulmonary adenomatosis) was transmitted to new-born lambs by inoculation of the microsomal fraction of a cytoplasmic extract of cultured tumour cells or tumour tissue. Various treatments of the biologically active fraction were carried out to differentiate between various classes of possible aetiological agents. The results obtained suggested the involvement of a membrane-associated RNA containing virus. Reverse transcriptase activity dependent on Mg++ was subsequently demonstrated in these extracts and in lung exudate, and was shown to be associated with particles banding at a density 1,175 in sucrose gradients. These characteristics, as well as the appearance of the particles in the electron microscope, are similar to those reported for Type B and Type D retroviruses. Serial transmissions of jaagsiekte over a number of years, using cytoplasmic extracts and purified virus, strongly suggest that this virus is the aetiologic agent of jaagsiekte.

Animals↗
PubMed1980

Presence of Herpesvirus ovis DNA sequences in cellular DNA from sheep lungs affected with jaagsiekte (pulmonary adenomatosis).

To investigate further the possible involvement of Herpesvirus ovis in the aetiology of jaagsiekte, the kinetics of reassociation of viral DNA and DNA isolated from tumour tissue as well as from cell cultures derived from it were studied. Although DNA-DNA hybridization could be demonstrated in 2 cases of jaagsiekte, no correlation was found between the presence of Herpesvirus ovis genome sequences and the occurrence of the disease.

Animals↗
PubMed1980

Aetiology of jaagsiekte: experimental transmission to lambs by means of cultured cells and cell homogenates.

Studies on the transmission of jaagsiekte (ovine pulmonary adenomatosis) both by subinoculation of cells of known sex and by cell homogenates into male and female lambs are reported. The results obtained indicate a thymocyte-dependent rejection of male cells in female recipients in contrast to the successful transplantation of male cells in male animals and female cells in both sexes. This suggests the presence of a surface antigen determined by the gamma-chromosome in the tumour cells. A second mechanism of transmission, dependent on the transformation of the recipient's cells, was demonstrated by 2 cases of heterologous transplantation and confirmed by inoculation of cellular homogenates.

Animals↗
PubMed1979

The serological relationship of herpesvirus ovis to other herpesviruses and its possible involvement in the aetiology of jaagsiekte.

Cross-neutralization studies showed that 3 different isolates of herpesvirus ovis from cell cultures derived from the lungs of sheep suffering from jaagsiekte were not only identical but were also related to similar isolate made in Scotland. No relationship, however, could be established between herpesvirus ovis and common bovine or equine herpesviruses. Antibodies to herpesvirus ovis were present in roughly 70% of all animals tested and no evidence was obtained for the involvement of the virus in the aetiology of jaagsiekte. On the other hand, the absence of antibodies in sheep sera from Iceland as well as the other data obtained in this study did not exclude involvement of the virus in jaagsiekte.

Animals↗
PubMed1978

Biochemical transformation of mouse cells by herpes simplex virus type 2: enhancement by means of low-level photodynamic treatment.

The biochemical transformation of thymidine kinase-deficient cells by UV-inactivated herpes simplex virus is enhanced by low-level photodynamic treatment of the infected cells. At the concentration of proflavine used, the virus was not inactivated and both virus and cellular DNA syntheses were only marginally inhibited. The observed enhancement of the transfer of a virus gene to the cell genome suggests a possible cocarcinogenic role for photodynamically active dyes at very low concentrations.

Acridines↗
PubMed1978

On the etiological role of Herpesvirus ovis in jaagsiekte.

Serologically related ovine herpesviruses have been isolated independently by various workers in different countries from adenomatous lung tissue of sheep or cell cultures derived from it. Although the disease can be transmitted with lung homogenates and with cell cultures, transmission attempts with virus alone failed. IUDR treatment of tumour-cell cultures and co-cultivation or fusion with cells permissive for virus replication induced antigens which react with some sera from tumour-bearing animals. These antigens give positive immunofluorescence reactions with sera both positive and negative in neutralization assays against the virus, however. Hybridization studies failed to demonstrate the presence of viral genomes in 15.4 tumour cells.

Animals↗
PubMed1977

Transplantation of cultured jaagsiekte (sheep pulmonary adenomatosis) cells into athymic nude mice.

Epithelial cells of the 15.4 line, which were originally established from the adenomatous lung of a jaagsieke case and which had been cultured in vitro for 22 generations, were injected subcutaneously into athymic nude mice. A slow-growing tumour which soon became cystic was established in each case. The cysts rapidly increased in size as a result of the accumulation of a slightly turbid secretion containing aggregates of tumour cells which rapidly refilled the cysts after the fluid had been withdrawn. Cultures were readily re-established from these cells and a chromosomal analysis proved that the tumor consisted of sheep cells. An epithelial cell lining, very similar to that found in the adenomatous lung alveoli of typical jaagsiekte, could be demonstrated histologically.

Animals↗
PubMed1977

Immunosuppression in new-born lambs.

A novel technique, based on cytotoxicity-neutralization, was developed for the in vitro titration of anti-sheep lymphocyte and anti-sheep macrophage sera. The titres obtained for a number of antisera were compared with those found in an agglutination assay. Anti-lymphocyte sera with a high cytotoxicity-neutralization titre very effectively suppressed the number of circulating lymphocytes in the peripheral blood of treated new-born lambs, thus indicating in vivo immunosuppressive activity.

Agglutination Tests↗
PubMed1976

Transmission of jaagsiekte (ovine pulmonary adenomatosis) by means of a permanent epithelial cell line established from affected lungs.

An epithelial cell line, designated JS-15,4, has been established in culture from jaagiekte lesions and subcultured in vitro for almost 2 years. It exhibits morphological and other features of transformed cells and has been shown by electron microscopy to consist of type B ovine alveolar epithelial cells. Jaagiekte was successfully transmitted to 3 new-born lambs by the intratracheal injection of cells following immunosuppressive treatment with either anti-thymocyte immunoglobulin alone or combined with anti-macrophage immunoglobulin. Incubation periods as short as 10 weeks were recorded. Evidence was also obtained that natural transmission may result from the inhalation of viable cells.

Aneuploidy↗
PubMed1975

Characteristics of an ovine herpesvirus associated with pulmonary adenomatosis (jaagsiekte) in sheep.

The isolation of an ovine herpesvirus from a cell culture of an adenomatous sheep lung is reported, confirming previous observations of a possible association of a herpesvirus with this tumour. Some growth properties and morphological characteristics of the virus are described, as well as serological data supporting a possible relationship between tumour and virus. Attempts to produce jaagsiekte by intratracheal injection of virus into lambs were unsuccessful, suggesting that a second factor may be involved inthe oncogenic process possibly similar to that proposed for the well-known EBV-Burkitt's lymphoma system.

Animals↗
PubMed1972

Structure of the bluetongue virus capsid.

Seven polypeptides were found to be present in the capsid of the bluetongue virus (BTV), four of which are major and three are minor components. This number and size distribution is the same as that found in reovirus, which has a similar segmented, double-stranded ribonucleic acid genome. In both viruses an excellent correlation is found between the molecular weights of certain genome segments and those of the polypeptides, suggesting a direct coding relationship between them. Careful comparison, however, indicates that the correlation patterns of the two viruses are different, suggesting that different genome segments may be utilized to code for certain capsid proteins. This phenomenon may be related to the fact that these viruses can be distinguished morphologically, reovirus having a larger diameter and possessing a double-layered capsid against the smaller single capsid of the BTV. Utilizing the degrading effect of CsCl gradients, it was demonstrated, however, that two of the BTV polypeptides are present as a diffuse protein layer surrounding the capsid. This outer layer probably has some of the functions of the reovirus outer capsid, one being the "masking" of a viral transcriptase which could be demonstrated after its removal.

Animals↗