INSTITUTO DE BIOTECNOLOGIA Y BIOLOGIA MOLECULAR
Unidad Ejecutora - UE
congresos y reuniones científicas
Avirulent factors expression on a virulent phenotype background alter the course of Bordetella pertussis infection in the murine model
ORMAZABAL MAXIMILIANO; FERNANDEZ JULIETA; CASTUMA CELINA; HOZBOR DANIELA
Simposio; 10th International Symposium on Bordetella; 2013
Trinity Biomedical Sciences Institute, Trinity College Dublin
There are only a few papers about the role of avirulence factors in Bordetella pertussis host interaction. Still, the reasons for the maintenance of these factors trough evolution deserve further invetigation. With this goal we developed a B. pertussis mutant unable to repress the expression of the avirulence factors in the virulent phase (vir+). This strain presents simultaneously characteristics of both virulent and avirulent phases. In particular, these mutant colonies growing on Bordet-Gengou agar show a mucous appearance together with a hemolytic halo. Moreover by qPCR assays similar expression levels were detected for the virulence marker Adenylate Cyclase between the mutant and the parental strain in vir + phase. The same results were obtained for the expression levels of the avirulence marker WbpO from the mutant and the parental strain in vir- phase. Regarding the growing characteristics in the liquid medium of Stainer-Sholter, the mutant presents a higher growth rate than the parental strain, indicating no impairment in cell division. Finally when assessing the infection kinetics in the murine model, the mutant demonstrated a decreased colonizing capacity at late periods of times in the course of the infection as compared to the parental strain. The numbers of colonies recovered from lungs (CFU) were similar in both strains until day 6, but at day 12 a significantly lower CFU value was obtained for the mutant and at day 18 no CFU were recovered. These results indicate that the avirulence factors have a detrimental role in the course of Bordetella pertussis infection.