Expression of the Flp proteins by <it>Haemophilus ducreyi </it>is necessary for virulence in human volunteers
<p>Abstract</p> <p>Background</p> <p><it>Haemophilus ducreyi</it>, the causative agent of the sexually transmitted disease chancroid, contains a <it>flp </it>(fimbria like protein) operon that encodes proteins predicted to contribute to adherence...
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| Format: | Article |
| Language: | English |
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BMC
2011-09-01
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| Series: | BMC Microbiology |
| Online Access: | http://www.biomedcentral.com/1471-2180/11/208 |
| _version_ | 1811260501071495168 |
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| author | Zwickl Beth W Fortney Kate R Katz Barry P Baker Beth Walsh Jessica Cooney Sean A Janowicz Diane M Ellinger Sheila Munson Robert S |
| author_facet | Zwickl Beth W Fortney Kate R Katz Barry P Baker Beth Walsh Jessica Cooney Sean A Janowicz Diane M Ellinger Sheila Munson Robert S |
| author_sort | Zwickl Beth W |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p><it>Haemophilus ducreyi</it>, the causative agent of the sexually transmitted disease chancroid, contains a <it>flp </it>(fimbria like protein) operon that encodes proteins predicted to contribute to adherence and pathogenesis. <it>H. ducreyi </it>mutants that lack expression of Flp1 and Flp2 or TadA, which has homology to NTPases of type IV secretion systems, have decreased abilities to attach to and form microcolonies on human foreskin fibroblasts (HFF). A <it>tadA </it>mutant is attenuated in its ability to cause disease in human volunteers and in the temperature dependent rabbit model, but a <it>flp1flp2 </it>mutant is virulent in rabbits. Whether a <it>flp </it>deletion mutant would cause disease in humans is not clear.</p> <p>Results</p> <p>We constructed 35000HPΔ<it>flp1-3</it>, a deletion mutant that lacks expression of all three Flp proteins but has an intact <it>tad </it>secretion system. 35000HPΔ<it>flp1-3 </it>was impaired in its ability to form microcolonies and to attach to HFF in vitro when compared to its parent (35000HP). Complementation of the mutant with <it>flp1-3 </it>in trans restored the parental phenotype. To test whether expression of Flp1-3 was necessary for virulence in humans, ten healthy adult volunteers were experimentally infected with a fixed dose of 35000HP (ranging from 54 to 67 CFU) on one arm and three doses of 35000HPΔ<it>flp1-3 </it>(ranging from 63 to 961 CFU) on the other arm. The overall papule formation rate for the parent was 80% (95% confidence interval, CI, 55.2%-99.9%) and for the mutant was 70.0% (95% CI, 50.5%-89.5%) (<it>P </it>= 0.52). Mutant papules were significantly smaller (mean, 11.2 mm<sup>2</sup>) than were parent papules (21.8 mm<sup>2</sup>) 24 h after inoculation (<it>P </it>= 0.018). The overall pustule formation rates were 46.7% (95% CI 23.7-69.7%) at 30 parent sites and 6.7% (95% CI, 0.1-19.1%) at 30 mutant sites (<it>P </it>= 0.001).</p> <p>Conclusion</p> <p>These data suggest that production and secretion of the Flp proteins contributes to microcolony formation and attachment to HFF cells in vitro. Expression of <it>flp1-3 </it>is also necessary for <it>H. ducreyi </it>to initiate disease and progress to pustule formation in humans. Future studies will focus on how Flp proteins contribute to microcolony formation and attachment in vivo.</p> |
| first_indexed | 2024-04-12T18:47:25Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 1471-2180 |
| language | English |
| last_indexed | 2024-04-12T18:47:25Z |
| publishDate | 2011-09-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Microbiology |
| spelling | doaj.art-97865aec0f104558adbdec63184d4c282022-12-22T03:20:34ZengBMCBMC Microbiology1471-21802011-09-0111120810.1186/1471-2180-11-208Expression of the Flp proteins by <it>Haemophilus ducreyi </it>is necessary for virulence in human volunteersZwickl Beth WFortney Kate RKatz Barry PBaker BethWalsh JessicaCooney Sean AJanowicz Diane MEllinger SheilaMunson Robert S<p>Abstract</p> <p>Background</p> <p><it>Haemophilus ducreyi</it>, the causative agent of the sexually transmitted disease chancroid, contains a <it>flp </it>(fimbria like protein) operon that encodes proteins predicted to contribute to adherence and pathogenesis. <it>H. ducreyi </it>mutants that lack expression of Flp1 and Flp2 or TadA, which has homology to NTPases of type IV secretion systems, have decreased abilities to attach to and form microcolonies on human foreskin fibroblasts (HFF). A <it>tadA </it>mutant is attenuated in its ability to cause disease in human volunteers and in the temperature dependent rabbit model, but a <it>flp1flp2 </it>mutant is virulent in rabbits. Whether a <it>flp </it>deletion mutant would cause disease in humans is not clear.</p> <p>Results</p> <p>We constructed 35000HPΔ<it>flp1-3</it>, a deletion mutant that lacks expression of all three Flp proteins but has an intact <it>tad </it>secretion system. 35000HPΔ<it>flp1-3 </it>was impaired in its ability to form microcolonies and to attach to HFF in vitro when compared to its parent (35000HP). Complementation of the mutant with <it>flp1-3 </it>in trans restored the parental phenotype. To test whether expression of Flp1-3 was necessary for virulence in humans, ten healthy adult volunteers were experimentally infected with a fixed dose of 35000HP (ranging from 54 to 67 CFU) on one arm and three doses of 35000HPΔ<it>flp1-3 </it>(ranging from 63 to 961 CFU) on the other arm. The overall papule formation rate for the parent was 80% (95% confidence interval, CI, 55.2%-99.9%) and for the mutant was 70.0% (95% CI, 50.5%-89.5%) (<it>P </it>= 0.52). Mutant papules were significantly smaller (mean, 11.2 mm<sup>2</sup>) than were parent papules (21.8 mm<sup>2</sup>) 24 h after inoculation (<it>P </it>= 0.018). The overall pustule formation rates were 46.7% (95% CI 23.7-69.7%) at 30 parent sites and 6.7% (95% CI, 0.1-19.1%) at 30 mutant sites (<it>P </it>= 0.001).</p> <p>Conclusion</p> <p>These data suggest that production and secretion of the Flp proteins contributes to microcolony formation and attachment to HFF cells in vitro. Expression of <it>flp1-3 </it>is also necessary for <it>H. ducreyi </it>to initiate disease and progress to pustule formation in humans. Future studies will focus on how Flp proteins contribute to microcolony formation and attachment in vivo.</p>http://www.biomedcentral.com/1471-2180/11/208 |
| spellingShingle | Zwickl Beth W Fortney Kate R Katz Barry P Baker Beth Walsh Jessica Cooney Sean A Janowicz Diane M Ellinger Sheila Munson Robert S Expression of the Flp proteins by <it>Haemophilus ducreyi </it>is necessary for virulence in human volunteers BMC Microbiology |
| title | Expression of the Flp proteins by <it>Haemophilus ducreyi </it>is necessary for virulence in human volunteers |
| title_full | Expression of the Flp proteins by <it>Haemophilus ducreyi </it>is necessary for virulence in human volunteers |
| title_fullStr | Expression of the Flp proteins by <it>Haemophilus ducreyi </it>is necessary for virulence in human volunteers |
| title_full_unstemmed | Expression of the Flp proteins by <it>Haemophilus ducreyi </it>is necessary for virulence in human volunteers |
| title_short | Expression of the Flp proteins by <it>Haemophilus ducreyi </it>is necessary for virulence in human volunteers |
| title_sort | expression of the flp proteins by it haemophilus ducreyi it is necessary for virulence in human volunteers |
| url | http://www.biomedcentral.com/1471-2180/11/208 |
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