| 1. |
- Destoumieux-Garzón, Delphine, et al.
(författare)
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Resistance to antimicrobial peptides in vibrios
- 2010
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Ingår i: Antibiotics. - : MDPI. - 2079-6382. ; 3:4, s. 540-563
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Forskningsöversikt (refereegranskat)abstract
- Vibrios are associated with a broad diversity of hosts that produce antimicrobial peptides (AMPs) as part of their defense against microbial infections. In particular, vibrios colonize epithelia, which function as protective barriers and express AMPs as a first line of chemical defense against pathogens. Recent studies have shown they can also colonize phagocytes, key components of the animal immune system. Phagocytes infiltrate infected tissues and use AMPs to kill the phagocytosed microorganisms intracellularly, or deliver their antimicrobial content extracellularly to circumvent tissue infection. We review here the mechanisms by which vibrios have evolved the capacity to evade or resist the potent antimicrobial defenses of the immune cells or tissues they colonize. Among their strategies to resist killing by AMPs, primarily vibrios use membrane remodeling mechanisms. In particular, some highly resistant strains substitute hexaacylated Lipid A with a diglycine residue to reduce their negative surface charge, thereby lowering their electrostatic interactions with cationic AMPs. As a response to envelope stress, which can be induced by membrane-active agents including AMPs, vibrios also release outer membrane vesicles to create a protective membranous shield that traps extracellular AMPs and prevents interaction of the peptides with their own membranes. Finally, once AMPs have breached the bacterial membrane barriers, vibrios use RND efflux pumps, similar to those of other species, to transport AMPs out of their cytoplasmic space.
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| 2. |
- Schmitt, Paulina, et al.
(författare)
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Immune responses in the Pacific oyster Crassostrea gigas : an overview with focus on summer mortalities
- 2012
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Ingår i: Oysters. - : Nova Science Publishers, Inc.. - 9781621005186 - 1621005186 - 9781621005575 ; , s. 227-273
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Bokkapitel (refereegranskat)abstract
- The Pacific oyster Crassostrea gigas is an important cultured species whose production has suffered from recurrent summer mortality events worldwide over the past two decades. In France, these mortality outbreaks have become devastating for the production of juvenile stages since 2008, and have resulted in great economic losses that currently threaten this activity. Studies on oyster immunity have been performed to better understand its response to pathogens, in particular to bacteria of the Vibrio genus and Herpes viruses, both found in moribund oysters. The immune response of C. gigas relies entirely on the innate immune system, in which hemocytes, the oyster circulating blood cells, are the main cellular mediators of the defense system. Activated when pathogen-associated molecular patterns are recognized by plasma soluble or cell surface pattern recognition receptors, hemocytes operate in a coordinated manner with soluble factors in the hemolymph to circumvent the infection. Over the past years, research efforts have substantially increased the knowledge of the molecular bases of oyster immunity, from non-self recognition proteins, to cytokines, signaling pathways and defense effectors including protease inhibitors, hydrolytic enzymes and antimicrobial peptides/proteins. This review describes the present state of our knowledge on the cellular and molecular effectors of oyster immunity, and describes the oyster responses to pathogenic Vibrio and Herpes species.
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