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A NEW ZEBRAFISH MODEL TO STUDY BACTERIAL PROBIOSIS


collaboration with J.P. Levraud, Macrophages and Development of Immunity Unit, Institut Pasteur

The beneficial contribution of commensal bacteria to host health led to the concept that exogenous and non-pathogenic bacteria (probiotics) could be used to prevent infectious disease. However, the absence of relevant experimentally tractable in vivo models severely limits our understanding of the molecular processes behind probiotic effects, therefore hampering prophylactic and therapeutic use of probiotics against infections.In collaboration with Jean-Pierre Levraud of the Macrophages and Development of Immunity Unit, we developed a protocol to raise microbe-free zebrafish larvae fed on microbe-free live food. We placed this microbiologically controlled model in contact with known pathogens and potential probiotics to investigate molecular events underlying pathogen exclusion by probiotic bacteria. We showed that Edwardsiella ictaluri, the causative agent of catfish enteric septicemia, causes rapid death of infected larvae following exposure via the natural immersion route. We used this mortality to screen potential probiotic bacteria able to extend zebrafish survival to E. ictaluri infection and thereby identified 3 protective strains. While host immune response modulation did not contribute to protection against E. ictaluri infection, comparison of protective and non-protective strains demonstrated a key role for their adhesion factors. Our in vivo approach constitutes a relevant new model of vertebrate oro-intestinal infection and provides new insight into molecular events underlying probiotic effects against incoming pathogens.

Rendueles, O.; Ferrieres, L.; Fretaud, M.; Begaud, E.; Hebomel, P.; Levraud, J.P. and J.M. Ghigo. (2012) A new zebrafish model of oro-intestinal pathogen colonization reveals a key role for adhesion in protection by probiotic bacteria. PLoS Pathogens. in press

A NEW IN VIVO MODEL OF CATHETER-ASSOCIATED BIOFILM INFECTIONS

We developed a rat model of totally implanted access port vascular catheter infection using luminescent biofilm-forming pathogens, including E. coli, Staphylococus aureus, S. epidermidis and P. aeruginosa. We showed that this model allows the non-invasive monitoring of biofilm infection in implanted animals.This new in vivo controlled model of biofilm infection will be used: 1) to characterize the different steps of in vivo infection ; 2) to evaluate the role of host immune responses in the dynamic of biofilm infections. 3) to evaluate the anti-biofilm potential of surface treatment using the different bacterial interference molecules identified in the laboratory.

 

 

 

 

 

 

 

 

 

 

 

 

Chauhan A.; Lebeaux, D.; Decante, B.;  Kriegel, I.; Escande, M.C.; Ghigo J.M. and C. Beloin. (2012) A rat model of long-term indwelling device reveals the importance of immune system in controlling biofilm establishment and related infections.PloS ONE. 2012;7(5):e37281