Les bovins sont-ils une source significative de Escherichia coli 0157:H7 ?

no. spécial

Study of the cytolethal distending toxin (CDT)-activated cell cycle checkpoint. Involvement of the CHK2 kinase.

AbstractThe bacterial cytolethal distending toxin (CDT) triggers a G2/M cell cycle arrest in eukaryotic cells by inhibiting the CDC25C phosphatase-dependent CDK1 dephosphorylation and activation. We report that upon CDT treatment CDC25C is fully sequestered in the cytoplasmic compartment, an effect that is reminiscent of DNA damage-dependent checkpoint activation. We show that the checkpoint kinase CHK2, an upstream regulator of CDC25C, is phosphorylated and activated after CDT treatment. In contrast to what is observed with other DNA damaging agents, we demonstrate that the activation of CHK2 can only take place during S-phase. Use of wortmannin and caffeine suggests that this effect is no…

Role of adhesive factor/rabbit2 in experimental enteropathogenic Eschiria coli O103 diarrhea of weaned rabbit

International audience

Detection of Escherichia coli strains producing cytotoxic necrotizing factor type two (CNF2) by enzyme-linked immunosorbent assay

Sheep and rabbit antisera were produced against lysates of E. coli strain 711 (pVir). This K-12 strain carries the Vir plasmid which codes for Cytotoxic Necrotizing Factor type 2 (CNF2). Immunoglobulin G (IgG) fractions of both immune sera were subsequently purified by a two-step precipitation method. To increase the specificity for CNF2, the sheep IgG preparation was extensively adsorbed against both a sonicated extract of isogenic K-12 strain 711 and intact phenol-treated cells of vaccine strain 711 (pVir). An enzyme-linked immunosorbent assay (ELISA) was developed to detect clinical isolates of E. coli producing CNF2, using the final preparations of rabbit and sheep IgG in a double sandw…

Intérêt des modèles cellulaires d'interaction dans l'étude du pouvoir pathogène des colibacilles producteurs de CNF et des colibacilles responsables des enterites du lapereau

Diarrhées colibacillaires néonatales du veau

Gastroenterologie bovine

Cytotoxins and fimbrial adhesins produced by Escherichia coli strains isolated from calves with diarrhea in Algeria

International audience

Type III Secretion-Dependent Cell Cycle Block Caused in HeLa Cells by Enteropathogenic Escherichia coliO103

ABSTRACT Rabbit enteropathogenic Escherichia coli (EPEC) O103 induces in HeLa cells an irreversible cytopathic effect characterized by the recruitment of focal adhesions, formation of stress fibers, and inhibition of cell proliferation. We have characterized the modalities of the proliferation arrest and investigated its underlying mechanisms. We found that HeLa cells that were exposed to the rabbit EPEC O103 strain E22 progressively accumulated at 4C DNA content and did not enter mitosis. A significant proportion of the cells were able to reinitiate DNA synthesis without division, leading to 8C DNA content. This cell cycle inhibition by E22 was abrogated in mutants lacking EspA, -B, and -D…

Sequence of lethal events in HeLa cells exposed to the G2 blocking cytolethal distending toxin

The bacterial cytolethal distending toxin (CDT) was previously shown to block the cell cycle of several cell lines at stage G2 through inactivation of the cyclin-dependent kinase Cdkl and without induction of DNA strand breaks. In the present study, we have analyzed, using various methods of analytical cytometry, the progressive transformation and delayed lethal events in the tumor-derived HeLa cell line temporarily exposed to CDT. The cell proliferation arrest induced by CDT was irreversible but, starting about two days after exposure, the G2 block released partially, concomitantly with a decline in the level of Cdkl phosphorylation. This partial release resulted in endoreduplication, lead…

Adhesion and cytopathic effect mutants: towards new oral vaccines against rabbit O103 colibacillosis

Cytotoxines et fimbriae produites par des souches Escherichia coli isolées de veaux diarrhéiques en Algérie

National audience

Interaction of Eschirichia coli producing cytotoxic necrotizing factor with hela epithelial cells

chap. 58

Vaccination orale contre les infections par les REPEC grâce à une souche bactérienne vivante atténuée double mutante

National audience

Cytolethal distending toxin (CDT): a bacterial weapon to control host cell proliferation ?

Cytolethal distending toxins (CDT) constitute a family of genetically related bacterial protein toxins able to stop the proliferation of numerous cell lines. This effect is due to their ability to trigger in target cells a signaling pathway that normally prevents the transition between the G2 and the M phase of the cell cycle. Produced by several unrelated Gram-negative mucosa-associated bacterial species, CDTs are determined by a cluster of three adjacent genes (cdtA, cdtB, cdtC) encoding proteins whose respective role is not yet fully elucidated. The CDT-B protein presents sequence homology to several mammalian and bacterial phosphodiesterases, such as DNase I. The putative nuclease activ…