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S Falkow

Publications and source records attributed to S Falkow.

347 records · Page 20Linked to original sources
PubMedDate not supplied

A single genetic locus encoded by Yersinia pseudotuberculosis permits invasion of cultured animal cells by Escherichia coli K-12.

For many species of pathogenic bacteria, invasion and survival within animal cells is central to establishing a successful host-parasite relationship. Localization within host cells protects the microorganism from host defences, or permits it to cross epithelial barriers and subsequently become systemically distributed. The precise mechanisms that permit entry of bacteria into host tissues are unclear, therefore we have been studying the invasion of epithelial cells by Yersinia pseudotuberculosis. As a first step towards identifying the factors required for this process, we report here the identification of a single genetic locus from this organism that is sufficient to convert the innocuous Escherichia coli K-12 strain into an organism capable of invading cultured animal cells.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Molecular Koch's postulates applied to microbial pathogenicity.

Microbial genetics and molecular cloning now permit us to routinely isolate specific genes from a variety of microbial pathogens. Obviously not all genes from pathogenic microorganisms play a role in pathogenicity or virulence. Just as Koch's postulates were formulated to identify the causal relationship between an organism and a specific disease, the notion is presented here that a form of molecular Koch's postulates is needed when examining the potential role of genes and their products in the pathogenesis of infection and disease.

Animals↗
PubMedDate not supplied

A molecular strategy for the study of bacterial invasion.

Bacterial populations are often clonal, and even within a bacterial species, the frequency of gene exchange and recombination is quite low. Consequently, mobile genetic elements--plasmids, bacteriophages, and transposons--have been the central factors in the evolution of pathogenic traits. One central feature of pathogenicity, the capacity to enter epithelial cells, is encoded by the bacterial chromosome of Yersinia pseudotuberculosis but by plasmid genes in enteroinvasive Escherichia coli. A single Yersinia gene, inv, which encodes a single 107,000-dalton protein, can be cloned in E. coli K12, and its presence is sufficient to permit the bacteria to enter cultured human cells. In contrast, fully 70 kilobases of a virulence plasmid from enteroinvasive E. coli must be transferred to E. coli K12 to achieve the same result. While researchers are at the early stages of understanding microbial entry into host cells, they can now investigate the molecular basis of this event in greater detail than has previously been possible.

Animals↗