[Epizootic-epidemiologic aspects of the Salmonella infection chain in poultry production]. / Epizootisch-epidemische Aspekte bei Salmonellen-Infektketten in der Geflügelproduktion.

Infections with S. typhimurium and S. enteritidis develop in poultry flocks as persistent flock enzootics, often without any clinical manifestation. Infected parenteral hen flocks are the source of vertical, so-called pseudo-trans-ovarian infection chains. These chains may induce horizontally self-maintaining cycles of the infection in the flocks. Environmental Salmonella may enter such cycles. Each of these cycles is able to transmit Salmonella to poultry products so entailing human health hazards permanently. The intensification in modern poultry production causes the permanent presence of Salmonella in the flocks. Hitherto all known control measures (biological, chemoprophylactic, physical) didn't result in a remarkable success. Therefore, the only alternative is the consequent implementation of hygiene regimes in all stages of production and during processing and marketing of poultry products in order to dilute Salmonella as much as possible.

Feeder cells from different sources and conditioned media for recloning of human--mouse and mouse--mouse hybridomas.

The use of different feeder cell layers (peritoneal macrophages from mice and rats, spleen cells and thymocytes from mice) for recloning of human--mouse and mouse--mouse hybridomas has been described. Optimal numbers of feeder cells from different sources required for high cloning efficiencies were determined. It was possible to use cryopreserved rat and mouse macrophages as feeders for cell cloning. However, the resulting cloning efficiency was much lower in comparison to the fresh material. Culture supernatants from human endothelial cells (added in a final concentration of 40% v/v) and from chicken embryo fibroblasts (25%) could replace the feeder cell layer in recloning experiments with both human--mouse and mouse--mouse hybridomas. Therefore, conditioned media (prepared in large quantities) may be used for generating standardized conditions for high-efficient cloning and recloning of hybridoma cell lines.

Detection of antibodies to avian reverse transcriptase by indirect ELISA.

An improved indirect ELISA test for detection of antibodies to the reverse transcriptase (revertase) is described. The sensitivity of the revertase ELISA test was compared to that of the revertase inhibition test. Serum samples of various origin and sera of specific pathogen free (SPF) hens were examined for the revertase antibodies. The presence of these antibodies in the sera of SPF chickens is discussed.

[Separation of cellular and viral DNA polymerase from oncornavirus infected chicken cells]. / Zur Trennung zellulärer und viruseigener DNA-Polymerasen aus onkornavirusinfizierten Zellen des Huhnes.

RNA-directed DNA polymerase was isolated from the liver, spleen, and myeloblasts of chickens that had been infected with virus of avian myeloblastosis. The enzyme was chromatographically purified from the myeloblasts and brought to about 1,000-fold concentration. The method consisted in cell fractionation, lysis of the microsomal fraction, chromatography on Sephadex G-200 and phosphocellulose, as well as ultracentrifugation in the glycerol gradient. The cellular DNA polymerases alpha and beta were clearly separated from the DNA polymerase of avian myeloblastosis virus and could be distinguished from one another by template-specific reactions. The viral DNA polymerase activities in the microsomal fractions of liver, spleen, and myeloblasts were compared with one another. The amount of avian myeloblastosis virus and related DNA polymerase recorded from the myeloblasts was about six times that in the liver and four times higher than that in the spleen. The procedure described, together with the use of cell fractionation and gel filtration, is an appropriate method for biochemical detection of avian oncorna viruses in cells.