EsiB, a novel pathogenic Escherichia coli secretory immunoglobulin A-binding protein impairing neutrophil activation.

Unlabelled: In this study, we have characterized the functional properties of a novel Escherichia coli antigen named EsiB (E. coli secretory immunoglobulin A-binding protein), recently reported to protect mice from sepsis. Gene distribution analysis of a panel of 267 strains representative of different E.

Staphylococcus aureus Staphopain A inhibits CXCR2-dependent neutrophil activation and chemotaxis.

The CXC chemokine receptor 2 (CXCR2) on neutrophils, which recognizes chemokines produced at the site of infection, plays an important role in antimicrobial host defenses such as neutrophil activation and chemotaxis. Staphylococcus aureus is a successful human pathogen secreting a number of proteolytic enzymes, but their influence on the host immune system is not well understood. Here, we identify the cysteine protease Staphopain A as a chemokine receptor blocker.

Pseudomonas aeruginosa alkaline protease blocks complement activation via the classical and lectin pathways.

The complement system rapidly detects and kills Gram-negative bacteria and supports bacterial killing by phagocytes. However, bacterial pathogens exploit several strategies to evade detection by the complement system. The alkaline protease (AprA) of Pseudomonas aeruginosa has been associated with bacterial virulence and is known to interfere with complement-mediated lysis of erythrocytes, but its exact role in bacterial complement escape is unknown.

Staphylococcus aureus metalloprotease aureolysin cleaves complement C3 to mediate immune evasion.

Complement is one of the first host defense barriers against bacteria. Activated complement attracts neutrophils to the site of infection and opsonizes bacteria to facilitate phagocytosis. The human pathogen Staphylococcus aureus has successfully developed ways to evade the complement system, for example by secretion of specific complement inhibitors.