Complex encounters at the macrophage-mycobacterium interface: studies on the role of the mannose receptor and CD14 in experimental infection models with Mycobacterium avium.

The initial interactions between mycobacterial cell wall components and receptor structures on the surface of macrophages may be critical in determining the outcome of infection. They may trigger the ingestion and digestion of microorganisms, but they may also promote the intracellular persistence and growth of mycobacteria. Using Mycobacterium avium as a model system, three approaches of different complexities were used to analyse some structural features and some functional consequences of M.

Inhibition of the type 1 fimbriae-mediated adhesion of Escherichia coli to erythrocytes by multiantennary alpha-mannosyl clusters: the effect of multivalency.

Alpha-mannosyl glycoclusters and glycodendrimers were tested as multivalent inhibitors of the type 1 (mannose-specific) fimbriae of a recombinant E. coli HB101 strain. Inhibition of haemagglutination of guinea pig erythrocytes was determined on microtiter plates.

Bacteriophages specifically recognizing the lipopolysaccharide antigens O4, O5, O6, and O7 of Escherichia coli.

Four bacteriophages recognizing the Escherichia coli lipopolysaccharide (LPS) antigens O4, O5, O6, and O7, respectively, were isolated from pooled sewage samples. Electron microscopic investigations revealed icosahedral phage structures. Phages phi O4, phi O5, and phi O7 belonged to Bradley's morphology group C, while phi O6 had a tail and resembles phages of group A of Bradley.

A simple procedure to demonstrate the presence of the O-antigen capsule in enteropathogenic Escherichia coli.

Enteropathogenic Escherichia coli O111 bacteria very often produce a capsule-like polysaccharide exhibiting the same chemical composition as the O-specific chains of their lipopolysaccharide and being designated as O-antigen capsule. In this paper, a new simple procedure is described for the detection of this capsule polymer. O-antigen capsule polysaccharide and lipopolysaccharide of bacterial extracts were electrophoretically separated in agarose cetavlon gel, blotted onto nitrocellulose membranes and visualized by immunological methods.

Isolation and characterization of bacteriophages specific for capsular antigens K3, K7, K12, and K13 of Escherichia coli.

Four bacteriophages recognizing the Escherichia coli capsular antigens K3, K7, K12, and K13, respectively, were isolated from pooled sewage samples. The nucleic acid of these phages was identified as double-stranded DNA of different size (phi K3, 71.3; phi K7, 32.

Two different Escherichia coli capsular polysaccharide depolymerases each associated with one of the coliphage phi K5 and phi K20.

The Escherichia coli capsular polysaccharides (K antigens) K5 and K20 are known as primary receptors for the coliphage phi K5 and phi K20, respectively. A host range study of the phage revealed that E. coli K5 strains were not only lysed by phi K5 but also by phi K20, and furthermore that the E.

Chromosomal mapping of genes encoding mannose-sensitive (type I) and mannose-resistant F8 (P) fimbriae of Escherichia coli O18:K5:H5.

DNA hybridization experiments demonstrated that the gene clusters encoding the F8 fimbriae (fei) as well as the type I fimbriae (pil) exist in a single copy on the chromosome of E. coli O18:K5 strain 2980. In conjugation experiments with appropriate donors, the chromosomal site of these gene clusters was determined.

Molecular cloning and expression of the O4 polysaccharide gene cluster from Escherichia coli.

The Escherichia coli O4 serotype is common among isolates from urinary tract infections. The genes responsible for the biosynthesis of the O4 polysaccharide in a human uropathogenic E. coli were cloned and expressed in E.

An improved method of ammonia determination, applicable to amidases and other ammonia-producing enzyme systems of mycobacteria.

The colorimetric estimation of amidase activity, using both qualitative and quantitative determinations of ammonia, is widely used for the differentiation of mycobacteria. At present the generally used phenol-hypochlorite method requires heating of the test solution to 90 degrees C for 30 min or to boiling for 5 min. At room temperature at least 2 h are necessary to obtain a full and stable color.

Nitrate reduction in so-called nitrate reductase (NR) negative strains of the genus Mycobacterium.

The goal of our present investigations was to complete our knowledge concerning the actual ability to reduce nitrate within the genus Mycobacterium and to eliminate previously reported results like "weakly reaction" or "variable reactions". The influence of conditions like reaction temperature and reaction time, substrate concentration, H+-donors, ammonia and the presence of the nitrate reductase were studied. The results can be summated as follows: 1.

[Nicotinamidase and the so-called pyrazinamidase in mycobacteria; the simultaneous occurrence of both activites (author's transl)].

Nicotin- and the so-called pyrazinamidase (in the following: "pyrazinamidase") have been found in strains of four mycobacteria species, M. fortuitum, M. gastri, M.