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Drosophila melanogaster as a model host for the Burkholderia cepacia complex.

Castonguay-Vanier J, Vial L, Tremblay J, Déziel E - PLoS ONE (2010)

Bottom Line: Colonization with bacterial species from the Burkholderia cepacia complex (Bcc) is associated with fast health decline among individuals with cystic fibrosis.While the feeding method proved unsuccessful at killing the flies, the pricking technique did generate mortality within the populations.Moreover, CI results indicate that this method is more sensitive than mortality tests.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Recherche Scientifique-Institut Armand Frappier, Laval, Canada.

ABSTRACT

Background: Colonization with bacterial species from the Burkholderia cepacia complex (Bcc) is associated with fast health decline among individuals with cystic fibrosis. In order to investigate the virulence of the Bcc, several alternative infection models have been developed. To this end, the fruit fly is increasingly used as surrogate host, and its validity to enhance our understanding of host-pathogen relationships has been demonstrated with a variety of microorganisms. Moreover, its relevance as a suitable alternative to mammalian hosts has been confirmed with vertebrate organisms.

Methodology/principal findings: The aim of this study was to establish Drosophila melanogaster as a surrogate host for species from the Bcc. While the feeding method proved unsuccessful at killing the flies, the pricking technique did generate mortality within the populations. Results obtained with the fruit fly model are comparable with results obtained using mammalian infection models. Furthermore, validity of the Drosophila infection model was confirmed with B. cenocepacia K56-2 mutants known to be less virulent in murine hosts or in other alternative models. Competitive index (CI) analyses were also performed using the fruit fly as host. Results of CI experiments agree with those obtained with mammalian models.

Conclusions/significance: We conclude that Drosophila is a useful alternative infection model for Bcc and that fly pricking assays and competition indices are two complementary methods for virulence testing. Moreover, CI results indicate that this method is more sensitive than mortality tests.

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Related in: MedlinePlus

Competitive index (CI) analysis of B. cenocepacia mutants in the D. melanogaster model.CI is defined as the ratio between the wild-type K56-2 and the mutant in the output (bacteria recovered from the fruit fly 96 h post infection) divided by their ratio in the input (inoculum). Each empty square represents the CI value obtained for one fly. A CI of less than 1 indicates a virulence defect. The mean of the CI is shown as a solid line. A. Three independent CI analyses performed with zmpA mutant. B. CI analyses of zmpA, zmpB and zmpA zmpB mutants. C. CI analyses of hldA, bscN, BCAL2831, cepI and cepR mutants. For htrA-, the CI was determined with strain RSF12 containing a mutation in the BCAL2831 gene.
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pone-0011467-g006: Competitive index (CI) analysis of B. cenocepacia mutants in the D. melanogaster model.CI is defined as the ratio between the wild-type K56-2 and the mutant in the output (bacteria recovered from the fruit fly 96 h post infection) divided by their ratio in the input (inoculum). Each empty square represents the CI value obtained for one fly. A CI of less than 1 indicates a virulence defect. The mean of the CI is shown as a solid line. A. Three independent CI analyses performed with zmpA mutant. B. CI analyses of zmpA, zmpB and zmpA zmpB mutants. C. CI analyses of hldA, bscN, BCAL2831, cepI and cepR mutants. For htrA-, the CI was determined with strain RSF12 containing a mutation in the BCAL2831 gene.

Mentions: In preliminary studies, we observed that the bacterial concentration used as inoculum or the choice of the time point for the output have no effect on the CI value (data not shown). Figure 6A shows three independent tests performed with the zmpA mutant that all produced very similar mean indices, confirming the reproducibility of the approach. For each experiment, the small variability between individual indices also highlights the precision of the results and further validates the method. In every case, mean CIs were all below 1, which indicates that the zmpA mutant is less competitive than the wild-type in vivo.


Drosophila melanogaster as a model host for the Burkholderia cepacia complex.

Castonguay-Vanier J, Vial L, Tremblay J, Déziel E - PLoS ONE (2010)

Competitive index (CI) analysis of B. cenocepacia mutants in the D. melanogaster model.CI is defined as the ratio between the wild-type K56-2 and the mutant in the output (bacteria recovered from the fruit fly 96 h post infection) divided by their ratio in the input (inoculum). Each empty square represents the CI value obtained for one fly. A CI of less than 1 indicates a virulence defect. The mean of the CI is shown as a solid line. A. Three independent CI analyses performed with zmpA mutant. B. CI analyses of zmpA, zmpB and zmpA zmpB mutants. C. CI analyses of hldA, bscN, BCAL2831, cepI and cepR mutants. For htrA-, the CI was determined with strain RSF12 containing a mutation in the BCAL2831 gene.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2902503&req=5

pone-0011467-g006: Competitive index (CI) analysis of B. cenocepacia mutants in the D. melanogaster model.CI is defined as the ratio between the wild-type K56-2 and the mutant in the output (bacteria recovered from the fruit fly 96 h post infection) divided by their ratio in the input (inoculum). Each empty square represents the CI value obtained for one fly. A CI of less than 1 indicates a virulence defect. The mean of the CI is shown as a solid line. A. Three independent CI analyses performed with zmpA mutant. B. CI analyses of zmpA, zmpB and zmpA zmpB mutants. C. CI analyses of hldA, bscN, BCAL2831, cepI and cepR mutants. For htrA-, the CI was determined with strain RSF12 containing a mutation in the BCAL2831 gene.
Mentions: In preliminary studies, we observed that the bacterial concentration used as inoculum or the choice of the time point for the output have no effect on the CI value (data not shown). Figure 6A shows three independent tests performed with the zmpA mutant that all produced very similar mean indices, confirming the reproducibility of the approach. For each experiment, the small variability between individual indices also highlights the precision of the results and further validates the method. In every case, mean CIs were all below 1, which indicates that the zmpA mutant is less competitive than the wild-type in vivo.

Bottom Line: Colonization with bacterial species from the Burkholderia cepacia complex (Bcc) is associated with fast health decline among individuals with cystic fibrosis.While the feeding method proved unsuccessful at killing the flies, the pricking technique did generate mortality within the populations.Moreover, CI results indicate that this method is more sensitive than mortality tests.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Recherche Scientifique-Institut Armand Frappier, Laval, Canada.

ABSTRACT

Background: Colonization with bacterial species from the Burkholderia cepacia complex (Bcc) is associated with fast health decline among individuals with cystic fibrosis. In order to investigate the virulence of the Bcc, several alternative infection models have been developed. To this end, the fruit fly is increasingly used as surrogate host, and its validity to enhance our understanding of host-pathogen relationships has been demonstrated with a variety of microorganisms. Moreover, its relevance as a suitable alternative to mammalian hosts has been confirmed with vertebrate organisms.

Methodology/principal findings: The aim of this study was to establish Drosophila melanogaster as a surrogate host for species from the Bcc. While the feeding method proved unsuccessful at killing the flies, the pricking technique did generate mortality within the populations. Results obtained with the fruit fly model are comparable with results obtained using mammalian infection models. Furthermore, validity of the Drosophila infection model was confirmed with B. cenocepacia K56-2 mutants known to be less virulent in murine hosts or in other alternative models. Competitive index (CI) analyses were also performed using the fruit fly as host. Results of CI experiments agree with those obtained with mammalian models.

Conclusions/significance: We conclude that Drosophila is a useful alternative infection model for Bcc and that fly pricking assays and competition indices are two complementary methods for virulence testing. Moreover, CI results indicate that this method is more sensitive than mortality tests.

Show MeSH
Related in: MedlinePlus