Invasion of enterocytes by Shigella flexneri requires the properly timed release of IpaB and IpaC at the host-pathogen interface; however, only IpaC has been found to possess quantifiable activities in vitro. We demonstrate here that when added to cultured cells, purified IpaC elicits cytoskeletal changes similar to those that occur during Shigella invasion. This IpaC effect may correlate with ...

Shigella proteins that are targeted to host cells by a type III secretion apparatus are essential for reorganization of the cytoskeleton during cell invasion. We have developed a semi-permeabilized cell assay that tests the effects of bacterial proteins on the actin cytoskeleton. The Shigella IpaC protein was found to induce the formation of filopodial and lamellipodial extensions in these semi...

Shigella flexneri causes a self-limiting gastroenteritis in humans, characterized by severe localized inflammation and ulceration of the colonic mucosa. Shigellosis most often targets young children in underdeveloped countries. Invasion plasmid antigen C (IpaC) has been identified as the primary effector protein for Shigella invasion of epithelial cells. Although an initial model of IpaC functi...

The primary effector for Shigella invasion of epithelial cells is IpaC, which is secreted via a type III secretion system. We recently reported that the IpaC N terminus is required for type III secretion and possibly other functions. In this study, mutagenesis was used to identify an N-terminal secretion signal and to determine the functional importance of the rest of the IpaC N terminus. The 1...

Background and Aims: Shigellosis is an acute gastroenteritis and Invasion plasmid antigen C (IpaC) is the first effector protein for Shigella invasion of intestinal cells. Among lactic acid bacteria, Bifidobacterium lactis (B. lactis) has received increasing attention for protection of a potential host against gastrointestinal infections. The aim of this study was to investigate the inhibitory ...

Type III secretion (T3S) systems are largely used by pathogenic gram-negative bacteria to inject multiple effectors into eukaryotic cells. Upon cell contact, these bacterial microinjection devices insert two T3S substrates into host cell membranes, forming a so-called 'translocon' that is required for targeting of type III effectors in the cell cytosol. Here, we show that secretion of the trans...

Shigella, the causative agent of bacillary dysentery, invades epithelial cells by locally reorganizing the actin cytoskeleton. Shigella invasion requires actin polymerization dependent on the Src tyrosine kinase and a functional bacterial type III secretion (T3S) apparatus. Using dynamic as well as immunofluorescence microscopy, we show that the T3S translocon component IpaC allows the recruitm...

Shigella flexneri invades colonic epithelial cells by pathogen-induced phagocytosis. The three proposed effectors of S. flexneri internalization are invasion plasmid antigens B (IpaB), IpaC, and IpaD, which are encoded on the pathogen's 230-kb virulence plasmid and translocated to the extracellular milieu via the Mxi-Spa translocon. To date, there are no definitive functional data for any purif...

We have investigated the capacity of live attenuated Shigella flexneri strains to act as vectors for the induction of local and systemic antibody responses against heterologous epitopes. The S. flexneri IpaC antigen was selected as a carrier protein into which the C3 neutralizing epitope of the poliovirus VP1 protein was inserted in eight sites distributed along IpaC. The resulting IpaC-C3 hybr...

I review the current knowledge of high-energy emission from extragalctic jets. First I discuss γ-ray emission from blazars, which provides us numerous precious information on the innermost portions of the relativistic jets. I describe the constraints on the dynamics of the jet from the subpc to the pc scale provided by recent VLBI studies of TeV sources, together with the modelling of the emiss...