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Stage conversion between tachyzoites and bradyzoites of Toxoplasma gondii was investigated in vitro by using murine bone marrow-derived macrophages (BMMs) as host cells. Following infection of untreated BMMs with tachyzoites, spontaneous expression of bradyzoite-specific antigens (Bsa) occurred at low frequency with Toxoplasma strain-dependent ratios from(More)
The flagellum is believed to be the common ancestor of all type III secretion systems (TTSSs). In Yersinia enterocolitica, expression of the flagellar TTSS and the Ysc (Yop secretion) TTSS are inversely regulated. We therefore hypothesized that the Ysc TTSS may adopt flagellar motor components in order to use the pathogenicity-related translocon in a(More)
A characteristic of the three human-pathogenic Yersinia spp. (the plague agent Yersinia pestis and the enteropathogenic Yersinia pseudotuberculosis and Yersinia enterocolitica) is the expression of the virulence (V)-antigen (LcrV). LcrV is a released protein which is involved in contact-induced secretion of yersinia antihost proteins and in evasion of the(More)
By using stage-specific monoclonal antibodies, an in vitro model has been developed to analyze the kinetics of expression of stage-specific antigens during the conversion process between tachyzoites and bradyzoites of Toxoplasma gondii. Following infection of murine macrophages with bradyzoites, the expression of bradyzoite-specific antigens declined,(More)
The non-fimbrial adhesins, YadA of enteropathogenic Yersinia species, and UspA1 and UspA2 of Moraxella catarrhalis, are established pathogenicity factors. In electron micrographs, both surface proteins appear as distinct 'lollipop'-shaped structures forming a novel type of surface projection on the outer membranes. These structures, amino acid sequence(More)
Fluorescence in situ hybridisation (FISH) targeted to ribosomal RNA is well established for studies in environmental microbiology. Initial applications of this technique in the field of medical microbiology showed that FISH is also a suitable means for the rapid, reliable and cultivation-independent identification of bacterial pathogens. In particular, for(More)
A monoclonal antibody generated against the mouse-lethal RH strain of Toxoplasma gondii was developed. Tachyzoites of virulent and avirulent T. gondii isolates grown in permanent macrophage cell cultures were examined for differences in reactivity with this antibody. Virulence of these Toxoplasma isolates was quantified by injecting different numbers of(More)
Yersinia enterocolitica O:3 was maintained in primary cultures of human synovial cells for 6 weeks as cultivable organisms and thereafter for 2 more weeks as antigen aggregates containing specific lipopolysaccharides (LPS). Some seemingly intact bacteria were "ghosts," bacterial rods possessing LPS but not DNA. The prolonged persistence of yersiniae, and(More)
To evaluate the value of single and nested PCRs for diagnosis of Pneumocystis carinii pneumonia (PCP) in a variety of respiratorily distressed patient groups, 574 respiratory samples from 334 patients (89 human immunodeficiency virus [HIV]-positive patients, 61 transplant recipients, 66 malignancy patients, 34 otherwise immunosuppressed patients, and 84(More)
In this study, we investigated the activity of transcription factor NF-kappaB in macrophages infected with Yersinia enterocolitica. Although triggering initially a weak NF-kappaB signal, Y. enterocolitica inhibited NF-kappaB activation in murine J774A.1 and peritoneal macrophages within 60 to 90 min. Simultaneously, Y. enterocolitica prevented prolonged(More)