|Director : GUISO Nicole (firstname.lastname@example.org)|
Bacteria from the Bordetella genus are responsible for respiratory infections in humans (Bordetella pertussis and Bordetella parapertussis and whooping cough) and in animals (Bordetella bronchiseptica and atrophic rhinitis and kennel cough). The researches developed in our laboratory are aimed to characterize the determinants involved in the pathogenicity of these bacteria, analyse the immune responses induced in the host after infection or vaccination, surveillance of polymorphism of clinical isolates and setting up of new prevention and new diagnosis for whooping cough and other bordetellosis.
I INTERACTIONS OF BORDETELLA PERTUSSIS, PARAPERTUSSIS AND BRONCHISEPTICA WITH HOST CELLS
Search for B.bronchiseptica target host cells [P. Gueirard in collaboration with P. Ave, M. Huerre, AM. Balazuc, G. Milon et S. Thiberge]
Using our murine respiratory model, we observed that a recrutment of CD11c positive dendritic leucocytes was detected in the bronchoalveolar lavage fluid and the lung respiratory epithelium early after infection. CD11c leucocyte population expansion was also observed on nasal mucosa associated-lymphoid tissue sections. Alive bacteria were recovered from these CD11c purified dendritic cells. These observations correlate with in vitro data demonstrating the persistence of B. bronchiseptica in a mouse dendritic cell line.
Interaction of Bordetella pertussis, parapertussis and bronchiseptica with human tracheal epithelial cells. [L. Bassinet, P. Gueirard in collaboration with the group of J.M. Cavaillon and the group of M.C. Prévost]
We continued the analysis of the three Bordetella species interactions with human tracheal epithelial cells. Although B. pertussis and B. parapertussis human isolates are not cytotoxic for these cells, some of B. bronchiseptica isolates are. Bacteria can persist inside the cells but do not multiply. B. pertussis isolates stimulate IL6 secretion by the host cells but only when they express toxins and adhesins. The toxins or adhesins responsable of this secretion are under characterization.
Interaction de Bordetella pertussis, parapertussis and bronchiseptica withmast cells [I. Tchou, L. Guillemot in collaboration with the group of S. Mecheri]
As for epithelial cells, B. pertussis and B. parapertussis human isolates are not cytotoxic whereas some B. bronchiseptica isolates are. Bacteria are invasive and the adhesin FHA is necessary for bacterial adhesion. Expression of ACHly toxin seems to inhibit bacterial invasivity.
II Polymorphism OF Bordetella pertussis, parapertussis AND bronchiseptica isolates
Analyse of the evolution of Bordetella pertussis population [V. Caro, G. Coralie, L. Guillemot, E. Njamkepo, F. Rimlinger and G. Soubigouin collaboration with N. Kourova and G. Tseneva from Institut Pasteur of Saint Petersbourg]
Analysis, by typing technique or sequencing of toxin and adhesin structural genes, of isolates circulating in France, a vaccinated country since more than thirty five years with a whole-cell vaccine, confirmed that B. pertussis isolates circulating before and after introduction of generalized vaccination are different. However, a precise analysis suggests that B. pertussis population could vary regularly every three years. The impact of the observed polymorphism is low in this country
Analysis of B. pertussis isolates from St Petersbourg (Russia) a country with a low vaccine coverage, was realized. The isolates circulating in 1998-2000 are very similar to those circulating in other European countries. This could be due to the fact that tourism is important in this area since a few years. Surprisingly, it was observed that the number of B. parapertussis infections is higher than in other European countries, Finland excepted. Some of these isolates are similar to those circulating in Europe but some express a different adhesin pertactin or PRN. Some of the differences are observed at the same location as in B. Bronchiseptica isolates.
Polymorphism of Bordetella adenylate-cyclase hemolysin structural gene [C. Boursaux-Eude, V. Caro, et F. Rimlinger]
No polymorphism was observed in B. pertussis and B. parapertussis isolates but an important polymorphism was observed with B. bronchiseptica isolates. This polymorphism is observed on the C-terminal part of the protein encoding the hemolysin and not at the N-terminal part encoding adenylate cyclase.
Study of chromosomal rearrangments in the Bordetella pertussis species (K. Dalet in collaboration with C. Weber]
Analysis of Bordetella pertussis clinical isolates revealed some plasticity of Bordetella pertussis chromosome. In fact, the modifications of the restriction profiles of the DNA of some of these isolates might be linked to a duplication or a deletion of a genome fragment. Studies are undertaken to understand the role of this plasticity.
III BORDETELLA BRONCHISEPTICA HUMAN AND ANIMAL INFECTIONS [E. Njamkepo, L. Guillemot]
B. bronchiseptica is a respiratory pathogen for many mamals species, including human. In human, B. bronchiseptica is considered as an opportunist pathogen for immunodepressed patient or patient with respiratory problems. We previously described that this bacterium can induce chronic infections. We confirmed the zoonotic character of this infection. The analysis of different B. bronchiseptica isolates indicate a higher polymorphism of isolates collected on dogs than collected on pigs. No isolate express pertussis toxin but they all express AC-Hly, FHA, PRN and a flagellum. However, pig isolates which express identical AC-Hly and PRN have very different pathogenicity in a murine model suggesting that other factors play a role on B. bronchiseptica pathogenicity.
Studies will continue because of the increase of immunocompromised patients, absence of cross protection of new pertussis vaccine, low efficacy of veterinary vaccines and antibiotic resistances carried by this bacterium.
IV CENTRE NATIONAL DE REFERENCE [G. Coralie, P. Gueirard, E. Njamkepo, G. Soubigou]
The missions of this Centre is to confirm the identification of Bordetella isolates collected in France, to maintain the collection, to teach French bacteriologists, to analyse isolates by Pulsed-Field-Gel Electrophoresis, as well as the toxins and adhesins they express, to set up sensitive and specific biological diagnosis techniques and to be part of the National surveillance net, RENACOQ, coordinated by the Ministery of Health.
Furthermore, we participated to different collaborative studies with PHLS (London) as experts for Bordetella serotyping.
V QUALITY INSURANCE [F. Fouque]
The set up of procedures and quality insurance in the laboratory was pursued.
Keywords: Whooping cough, Bordetella pertussis, Bordetella parapertussis, Bordetella bronchiseptica, vaccine, immunity, chronic infection
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|Office staff||Researchers||Scientific trainees||Other personnel|
|Langlais Laurence -email@example.com||GUEIRARD Pascale – Chargée de Recherche IP –firstname.lastname@example.org
GUISO Nicole– head of the unit IP –email@example.com
|BASSINET Laurence – étudiante en thèse – firstname.lastname@example.org
CARO Valérie – post-doc– stagiaire post-doctorale –email@example.com
DALET Karine – post-doc – stagiaire post-doctorale since april 2002 –firstname.lastname@example.org
TCHOU Isabelle – post-doc – stagiaire post-doctorale since april 2002 –email@example.com
|CORALIE Gilberte – Technicienne IP gagée –firstname.lastname@example.org
FOUQUE Françoise – Ingénieur IP –email@example.com
GUILLEMOT Laurent - Technicien supérieur IP gagé –firstname.lastname@example.org
NJAMKEPO Elisabeth – Ingénieur IP –email@example.com
RIMLINGER François – Technicien supérieur IP gagé –firstname.lastname@example.org
SOUBIGOU Guillaume– Technicien supérieur IP –email@example.com
BLERIOT Martine – Aide de laboratoire, (sharing with the Agents antibactériens unit)
FAVRE-ROCHEX Sandrine– Aide de laboratoire,(sharing with Agents antibactériens unit)
LAURET Marie-Reine – Agent de laboratoire, (sharing with Agents antibactériens unit)
SAGOT Pierre– Agent de laboratoire, (sharing with Agents antibactériens unit)