Biological properties of Estero Real virus.
The pathogenicity for animals, multiplication characteristics in animals, chick embryos and cells, and antibody formation to the Estero Real (ER) virus are reported.
Biomedical subjects
Publications and source records attributed to Z Marhoul.
The pathogenicity for animals, multiplication characteristics in animals, chick embryos and cells, and antibody formation to the Estero Real (ER) virus are reported.
Four infectious agents were isolated from the ticks Ixodes ricinus (L.) collected in the recreational area and park-forest of Prague. On the basis of cultivation, staining, biochemical, serologic properties, pathogenicity for animals and histological tests they were identified as Francisella tularensis with the following features: they are short, gram-negative rods of approximate dimensions of 0.3 X 0.8 micron, growing in enriched media after 3-4 day incubation at 37 degrees C. They form small circular, at first transparent, later greyish turbid colonies with regular rims. They are little active biochemically. They are susceptible to streptomycin and some broad spectrum antibiotics. They react positively with tularemic serum, but in lower titres than those in which this serum reacts with standard antigen. The microbes are highly pathogenic for mice, guinea-pigs, young rats, in which a massive bacteriemia occurs before death, but they do not kill rabbits. They multiply well in chick embryo, but do not grow in cell or tissue cultures. The most important histologic changes were observed in liver and spleen of mice. No pathologic changes were found in brain, lungs, heart, kidneys. Necroses were found in liver and in their marginal zones the microbes were present. Conspicuous were changes in numerous hepatocytes which became enlarged due to microbial multiplication and finally transformed into "sacs" packed with microbes. Histological and electronoptical examination showed that these are intracellular parasites fringed with a light lytic zone. Discussed is the problem to what extent the properties of the isolated strains are typical of F. tularensis as well as the importance of their detection from the aspect of epidemiology and differential diagnostics.
The indirect IF technique, using suspensions of TBE virus infected and uninfected PS cells as antigen-containing substrate, furnishes a rapid and practical test making possible the detection of specific IgM class serum antibodies in the initial stage of clinically manifest TBE. It enables early confirmation of diagnosis already in the acute phase of the disease and thus it can be instrumental in differential diagnosis and rational therapy, e.g., the administration of specific hyperimmune gamma-globulin.
The influence of temperature of 36.5 and 39.2 degrees C on uncloned low passage Tahyna virus in chick embryo cell cultures was studied in the course of 10 passages. At a high multiplicity of infection, the virus titres showed a considerable variability, especially at 39.2 degrees C. The cytopathic effect (CPE) apparent at both temperatures started later and was of lower intensity at 39.2 degrees C than at 36.5 degrees C. The temperature of 39.2 degrees C intensified the thermostable character of the virus. Changes in plaque size and virulence were connected mainly with the cultivation substrate of the virus.
The behaviour of uncloned, low-passage Tahyna virus in an Aedes albopictus (AA) cell line at 28 and 20 degrees C was studied in the course of 10 passages. The virus multiplied at both temperatures without any apparent effect on the host cell. At 28 and 20 degrees C reduction of plaque size, decrease of peripheral virulence and weakening of thermostability were observed. Differences between both temperatures were only in the intensity of these changes.
Lednice (Yaba 1) virus was found to multiply in primary cultures of goose, duck and chick embryo cells. The size of inoculum and age of embryos used for preparation of primary cultures was decisive for the amount of multiplied virus. One strain (110) of Lednice virus showed reduced ability to induce a cytopathic effect in the first passage in chick embryo cells. Virus multiplication in all three kinds of cells was confirmed by immunofluorescence.
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