Ulrich Methner

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Day-old chicks are very susceptible to infections with Salmonella enterica subspecies. The gut mucosa is the initial site of host invasion and provides the first line of defense against the bacteria. To study the potential of different S. enterica serovars to invade the gut mucosa and trigger an immune response, day-old chicks were infected orally with(More)
A recent European Union Directive required member states to put monitoring and control programmes in place, of which vaccination is a central component. Live Salmonella vaccines generally confer better protection than killed vaccines, because the former stimulate both cell-mediated and humoral immunity. Administering Salmonella bacteria orally to newly(More)
Three outer membrane proteins of Salmonella enterica serovar Typhimurium function as catecholate siderophore receptors. IroN promotes uptake of enterobactin, salmochelins and 2,3-dihydroxybenzoylserine, FepA transports enterobactin and 2,3-dihydroxybenzoylserine, and Cir is a receptor for 2,3-dihydroxybenzoylserine. In addition, all three proteins are(More)
Vaccination and competitive exclusion (CE) represent accepted prophylactic measures to control Salmonella infections in chickens. To use the advantages of both the CE technique and vaccination with live Salmonella vaccines the combination of these methods was studied. In three experiments, SPF chickens were pre-treated using combined or unique(More)
Administration of live Salmonella strains to day-old chicks provides profound protection against superinfection with a related strain within a matter of hours by a colonisation-inhibition mechanism, which is primarily a bacterial physiological process. Although currently available, commercial, live attenuated Salmonella vaccines induce protection by(More)
Apart from Salmonella monitoring of pig herds during the period of growth to evaluate the efficacy of control programmes, monitoring at harvest level is of relevance to assess the Salmonella status of fattening pigs and the associated risk of introducing Salmonella organisms in the slaughter process. Samples from 1830 fattening pigs were gathered at(More)
A total of 105 specific pathogen-free (SPF) laying hens and eight cocks were orally infected with strains of Salmonella enteritidis. The organs of these animals were examined bacteriologically for up to 6 weeks post infectionem (p.i.). One-half of the eggs laid on a single day were examined 1 day after laying, and the other half 28 days after laying. The(More)
Despite the fact that, in a number of countries, vaccination programmes are extensively used to control Salmonella infection in poultry, information on the immune mechanisms, especially the cellular response, is still needed. The aim of the study was to characterise the B cell and macrophage response in caecum (IgA+, IgM+, IgG+ cells, macrophages), bursa of(More)
Single, double, and triple mutants of an enterobactin-deficient mutant strain of Salmonella enterica serovar Typhimurium were constructed that were defective in the expression of the iron-regulated outer membrane proteins (IROMPs) FepA, IroN, and Cir, which are proposed to function as catecholate receptors. Uptake of naturally occurring and chemically(More)
Norepinephrine promotes the growth of Salmonella enterica in vitro in iron-restricted conditions imposed by the iron-binding proteins serum transferrin and egg-white ovotransferrin by facilitating the release of bound iron and subsequent uptake by the bacteria. Moreover, significantly increased colonisation and systemic spread were observed in mouse and(More)