SCAN: Virulence of Enterococcus faecalis dairy strains in an insect model: Role of fsrB and gelE genes
Frederic Gaspar, Microbiology of Man-Made Environments Lab.
| When |
20 May, 2009
from
12:00 pm to 01:00 pm |
|---|---|
| Where | Auditorium |
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Abstract
Despite the existence of various virulence factors in the Enterococcus genus, enterococcal virulence is still a debated issue. A main consideration is the detection of the same virulence genes in strains isolated from nosocomial or community acquired infections, and from food products. The goal of this study was to evaluate the roles of two well characterized enterococcal virulence factors, Fsr and GelE, in the potential virulence of Enterococcus faecalis food strains.
Virulence of unrelated Enterococcus isolates including dairy strains carrying fsr and gelE operons was compared in the Galleria mellonella insect model. E. faecalis dairy strains were able to kill larvae and were as virulent as the strain OG1RF, one of the most used for virulence studies. In contrast, E. durans and E. faecium strains were avirulent or poorly virulent for G. mellonella. To evaluate the role of fsrB and gelE genes in virulence of the E. faecalis dairy strains, both genes were deleted independently in two strains. The ΔfsrB and ΔgelE deletion mutants both presented a gelatinase-negative phenotype.
Although both mutations significantly attenuated virulence in G. mellonella, the ΔfsrB strains were more strongly attenuated. These results agree with previous findings suggesting the involvement of fsrB in the control of other cell functions relevant for virulence.
Our work demonstrates that the presence of functional fsrB and to a lesser extent gelE in dairy enterococci should be considered with caution.
Short CV:
1996-2002: Degree in Biochemistry by Faculdade de Ciências da Universidade de Lisboa.
2002-2004: Research student in the Physiology of Environmentally Conditioned Microbiota group at ITQB, under the supervision of Maria Vitoria San Romão.
Since 2004: PhD student in the Antibiotic Stress and Virulence of Enterococci and Microbiology of Man-made Environments groups in ITQB, under the supervision of Maria de Fátima Silva Lopes and Teresa Crespo.
