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Relative Contribution of P5 and Hap Surface Proteins to Nontypable Haemophilus influenzae Interplay with the Host Upper and Lower Airways.

Euba B, Moleres J, Viadas C, Ruiz de los Mozos I, Valle J, Bengoechea JA, Garmendia J - PLoS ONE (2015)

Bottom Line: Hap involvement in NTHi375-host interaction was shown to be limited, despite promoting bacterial cell adhesion when expressed in H. influenzae RdKW20.We also show that Hap does not contribute to bacterial biofilm growth, and that its absence partially restores the deficiency in lung infection observed for the ΔompP5 mutant.Altogether, this work frames the relative importance of the P5 and Hap surface proteins in NTHi virulence.

View Article: PubMed Central - PubMed

Affiliation: Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain; Instituto de Agrobiotecnología, CSIC-Universidad Pública Navarra-Gobierno Navarra, Mutilva, Spain.

ABSTRACT
Nontypable Haemophilus influenzae (NTHi) is a major cause of opportunistic respiratory tract disease, and initiates infection by colonizing the nasopharynx. Bacterial surface proteins play determining roles in the NTHi-airways interplay, but their specific and relative contribution to colonization and infection of the respiratory tract has not been addressed comprehensively. In this study, we focused on the ompP5 and hap genes, present in all H. influenzae genome sequenced isolates, and encoding the P5 and Hap surface proteins, respectively. We employed isogenic single and double mutants of the ompP5 and hap genes generated in the pathogenic strain NTHi375 to evaluate P5 and Hap contribution to biofilm growth under continuous flow, to NTHi adhesion, and invasion/phagocytosis on nasal, pharyngeal, bronchial, alveolar cultured epithelial cells and alveolar macrophages, and to NTHi murine pulmonary infection. We show that P5 is not required for bacterial biofilm growth, but it is involved in NTHi interplay with respiratory cells and in mouse lung infection. Mechanistically, P5NTHi375 is not a ligand for CEACAM1 or α5 integrin receptors. Hap involvement in NTHi375-host interaction was shown to be limited, despite promoting bacterial cell adhesion when expressed in H. influenzae RdKW20. We also show that Hap does not contribute to bacterial biofilm growth, and that its absence partially restores the deficiency in lung infection observed for the ΔompP5 mutant. Altogether, this work frames the relative importance of the P5 and Hap surface proteins in NTHi virulence.

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Bacterial loads in the lungs of CD1 mice infected by NTHi375 mutant strains lacking the ompP5 and hap genes.Mice were infected intranasally with ~108 bacteria. Bacterial counts in lungs at 24 or 48 h PI were determined. Results are reported as log10 c.f.u./lung. Statistical differences were seen at 48 h PI.
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pone.0123154.g006: Bacterial loads in the lungs of CD1 mice infected by NTHi375 mutant strains lacking the ompP5 and hap genes.Mice were infected intranasally with ~108 bacteria. Bacterial counts in lungs at 24 or 48 h PI were determined. Results are reported as log10 c.f.u./lung. Statistical differences were seen at 48 h PI.

Mentions: We have previously assessed NTHi persistence on a mouse infection model by intranasal inoculation of CD1 mice with NTHi375 [29]. In this study, we sought to determine the impact of P5 and Hap deficiency in mouse lung infection. We quantified bacterial loads for wild-type and each mutant from lung homogenates of infected mice at 24 and 48 h post-infection (PI). We recovered comparable bacterial numbers for NTHi375 wild-type, ΔompP5, Δhap, and ΔompP5Δhap strains at 24 h PI (Fig 6A). Conversely, at 48 h PI, we recovered significantly fewer bacteria for NTHi375ΔompP5 (p<0.001) and ΔompP5Δhap (p<0.05) than for the wild-type strain (Fig 6B). NTHi375Δhap delivered counts indistinguishable from those obtained after infection with the wild-type strain. Of note, NTHi375ΔompP5Δhap rendered a significant increase in the number of bacteria recovered, when compared to NTHi375ΔompP5 (p<0.05). These data indicate that P5 may delay the clearance of NTHi in mouse pulmonary infection. Hap does not seem to contribute to NTHi persistence in the mouse lung, and its absence partially restores the deficiency in lung infection observed for the NTHi375ΔompP5 mutant strain.


Relative Contribution of P5 and Hap Surface Proteins to Nontypable Haemophilus influenzae Interplay with the Host Upper and Lower Airways.

Euba B, Moleres J, Viadas C, Ruiz de los Mozos I, Valle J, Bengoechea JA, Garmendia J - PLoS ONE (2015)

Bacterial loads in the lungs of CD1 mice infected by NTHi375 mutant strains lacking the ompP5 and hap genes.Mice were infected intranasally with ~108 bacteria. Bacterial counts in lungs at 24 or 48 h PI were determined. Results are reported as log10 c.f.u./lung. Statistical differences were seen at 48 h PI.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4403991&req=5

pone.0123154.g006: Bacterial loads in the lungs of CD1 mice infected by NTHi375 mutant strains lacking the ompP5 and hap genes.Mice were infected intranasally with ~108 bacteria. Bacterial counts in lungs at 24 or 48 h PI were determined. Results are reported as log10 c.f.u./lung. Statistical differences were seen at 48 h PI.
Mentions: We have previously assessed NTHi persistence on a mouse infection model by intranasal inoculation of CD1 mice with NTHi375 [29]. In this study, we sought to determine the impact of P5 and Hap deficiency in mouse lung infection. We quantified bacterial loads for wild-type and each mutant from lung homogenates of infected mice at 24 and 48 h post-infection (PI). We recovered comparable bacterial numbers for NTHi375 wild-type, ΔompP5, Δhap, and ΔompP5Δhap strains at 24 h PI (Fig 6A). Conversely, at 48 h PI, we recovered significantly fewer bacteria for NTHi375ΔompP5 (p<0.001) and ΔompP5Δhap (p<0.05) than for the wild-type strain (Fig 6B). NTHi375Δhap delivered counts indistinguishable from those obtained after infection with the wild-type strain. Of note, NTHi375ΔompP5Δhap rendered a significant increase in the number of bacteria recovered, when compared to NTHi375ΔompP5 (p<0.05). These data indicate that P5 may delay the clearance of NTHi in mouse pulmonary infection. Hap does not seem to contribute to NTHi persistence in the mouse lung, and its absence partially restores the deficiency in lung infection observed for the NTHi375ΔompP5 mutant strain.

Bottom Line: Hap involvement in NTHi375-host interaction was shown to be limited, despite promoting bacterial cell adhesion when expressed in H. influenzae RdKW20.We also show that Hap does not contribute to bacterial biofilm growth, and that its absence partially restores the deficiency in lung infection observed for the ΔompP5 mutant.Altogether, this work frames the relative importance of the P5 and Hap surface proteins in NTHi virulence.

View Article: PubMed Central - PubMed

Affiliation: Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain; Instituto de Agrobiotecnología, CSIC-Universidad Pública Navarra-Gobierno Navarra, Mutilva, Spain.

ABSTRACT
Nontypable Haemophilus influenzae (NTHi) is a major cause of opportunistic respiratory tract disease, and initiates infection by colonizing the nasopharynx. Bacterial surface proteins play determining roles in the NTHi-airways interplay, but their specific and relative contribution to colonization and infection of the respiratory tract has not been addressed comprehensively. In this study, we focused on the ompP5 and hap genes, present in all H. influenzae genome sequenced isolates, and encoding the P5 and Hap surface proteins, respectively. We employed isogenic single and double mutants of the ompP5 and hap genes generated in the pathogenic strain NTHi375 to evaluate P5 and Hap contribution to biofilm growth under continuous flow, to NTHi adhesion, and invasion/phagocytosis on nasal, pharyngeal, bronchial, alveolar cultured epithelial cells and alveolar macrophages, and to NTHi murine pulmonary infection. We show that P5 is not required for bacterial biofilm growth, but it is involved in NTHi interplay with respiratory cells and in mouse lung infection. Mechanistically, P5NTHi375 is not a ligand for CEACAM1 or α5 integrin receptors. Hap involvement in NTHi375-host interaction was shown to be limited, despite promoting bacterial cell adhesion when expressed in H. influenzae RdKW20. We also show that Hap does not contribute to bacterial biofilm growth, and that its absence partially restores the deficiency in lung infection observed for the ΔompP5 mutant. Altogether, this work frames the relative importance of the P5 and Hap surface proteins in NTHi virulence.

Show MeSH
Related in: MedlinePlus