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Cao D, Subhadra B, Lee YJ, Thoresen M, Cornejo S, Olivier A, Woolums A, Inzana TJ. Contribution of Hfq to gene regulation and virulence in Histophilus somni. Infect Immun 2024; 92:e0003824. [PMID: 38391206 PMCID: PMC10929436 DOI: 10.1128/iai.00038-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024] Open
Abstract
Histophilus somni is one of the predominant bacterial pathogens responsible for bovine respiratory and systemic diseases in cattle. Despite the identification of numerous H. somni virulence factors, little is known about the regulation of such factors. The post-transcriptional regulatory protein Hfq may play a crucial role in regulation of components that affect bacterial virulence. The contribution of Hfq to H. somni phenotype and virulence was investigated following creation of an hfq deletion mutant of H. somni strain 2336 (designated H. somni 2336Δhfq). A comparative analysis of the mutant to the wild-type strain was carried out by examining protein and carbohydrate phenotype, RNA sequence, intracellular survival in bovine monocytes, serum susceptibility, and virulence studies in mouse and calf models. H. somni 2336Δhfq exhibited a truncated lipooligosaccharide (LOS) structure, with loss of sialylation. The mutant demonstrated increased susceptibility to intracellular and serum-mediated killing compared to the wild-type strain. Transcriptomic analysis displayed significant differential expression of 832 upregulated genes and 809 downregulated genes in H. somni 2336Δhfq compared to H. somni strain 2336, including significant downregulation of lsgB and licA, which contribute to LOS oligosaccharide synthesis and sialylation. A substantial number of differentially expressed genes were associated with polysaccharide synthesis and other proteins that could influence virulence. The H. somni 2336Δhfq mutant strain was attenuated in a mouse septicemia model and somewhat attenuated in a calf intrabronchial challenge model. H. somni was recovered less frequently from nasopharyngeal swabs, endotracheal aspirates, and lung tissues of calves challenged with H. somni 2336Δhfq compared to the wild-type strain, and the percentage of abnormal lung tissue in calves challenged with H. somni 2336Δhfq was lower than in calves challenged with the wild-type strain. In conclusion, our results support that Hfq accounts for the regulation of H. somni virulence factors.
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Affiliation(s)
- Dianjun Cao
- Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, New York, USA
| | - Bindu Subhadra
- Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, New York, USA
| | - Yue-Jia Lee
- Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, New York, USA
| | - Merrilee Thoresen
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA
| | - Santiago Cornejo
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA
| | - Alicia Olivier
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA
| | - Amelia Woolums
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA
| | - Thomas J. Inzana
- Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, New York, USA
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García JFM, Rojas L, Zenteno E, Cruz CV, Abascal EN. Characterization of Actinobacillus seminis biofilm formation. Antonie Van Leeuwenhoek 2020; 113:1371-1383. [PMID: 32671613 DOI: 10.1007/s10482-020-01447-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 07/08/2020] [Indexed: 11/27/2022]
Abstract
Actinobacillus seminis is an autochthonous gram-negative bacterium that affects reproductive organs, causing epididymitis, low fertility, and occasional abortions in ovine and goats. The virulence factors and the pathogenicity mechanisms of A. seminis have not been clearly elucidated yet. In this work, biofilm production by A. seminis in in vitro assays is described and characterized. After 48-h incubation at 37 °C in trypticase soy broth, A. seminis formed biofilms containing an extracellular matrix comprised mainly of fibrillar material. Microaerophilia or the presence of calcium diminished biofilm formation in approximately 50% and 70%, respectively, but low iron concentrations increased it 40%. Through enzymatic digestion, it was found that proteins were the main component of these biofilms. Structural observations through scanning electron microscopy indicated the presence of a high amount of fibrillar material in which bacteria were immersed. Antibodies against different bacterial surface proteins, such as anti-biofilm matrix and anti-adhesin, diminished biofilm formation in 70% and 25%, respectively; whereas furanone C-30 and LED-209, compounds described as quorum-sensing inhibitors, completely inhibited biofilm formation. In conclusion, environmental conditions can influence strongly biofilm formation in A. seminis, and this could be an advantageous strategy that allows bacteria to persist inside a host.
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Affiliation(s)
- J Fernando Montes García
- Carrera de Biología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México (UNAM), Av. de los Barrios #1, Los Reyes Iztacala, 54090, Tlalnepantla, State of Mexico, Mexico.,Licenciatura en Nutrición, Unidad Académica Profesional Acolman, Universidad Autónoma del Estado de Mexico, Acolman, Estado de Mexico, Mexico
| | - Lourdes Rojas
- Laboratorio Nacional de Servicios Experimentales, Centro de Investigación y de Estudios Avanzados del IPN, Av. IPN 2508, Zacatenco, 07360, Mexico City, Mexico
| | - Edgar Zenteno
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Candelario Vazquez Cruz
- Centro de Investigaciones en Ciencias Microbiológicas, BUAP, Apdo. Postal 1622, 72560, Puebla, Puebla, Mexico
| | - Erasmo Negrete Abascal
- Carrera de Biología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México (UNAM), Av. de los Barrios #1, Los Reyes Iztacala, 54090, Tlalnepantla, State of Mexico, Mexico.
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Histophilus somni Survives in Bovine Macrophages by Interfering with Phagosome-Lysosome Fusion but Requires IbpA for Optimal Serum Resistance. Infect Immun 2018; 86:IAI.00365-18. [PMID: 30201700 DOI: 10.1128/iai.00365-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 09/01/2018] [Indexed: 11/20/2022] Open
Abstract
Histophilus somni is capable of intracellular survival within professional phagocytic cells, but the mechanism of survival is not understood. The Fic motif within the direct repeat (DR1)/DR2 domains of the IbpA fibrillary network protein of H. somni is cytotoxic to epithelial and phagocytic cells, which may interfere with the bactericidal activity of these cells. To determine the contribution of IbpA and Fic to resistance to host defenses, H. somni strains and mutants that lacked all or a region of ibpA (including the DR1/DR2 regions) were tested for survival in bovine monocytic cells and for serum susceptibility. An H. somni mutant lacking IbpA, but not the DR1/DR2 region within ibpA, was more susceptible to killing by antiserum than the parent, indicating that the entire protein was associated with serum resistance. H. somni strains expressing IbpA replicated in bovine monocytes for at least 72 h and were toxic for these cells. Virulent strain 2336 mutants lacking the entire ibpA gene or both DR1 and DR2 were not toxic to the monocytes but still survived within the monocytes for at least 72 h. Monitoring of intracellular trafficking of H. somni with monoclonal antibodies to phagosomal markers indicated that the early phagosomal marker early endosome antigen 1 colocalized with all isolates tested, but only strains that could survive intracellularly did not colocalize with the late lysosomal marker lysosome-associated membrane protein 2 and prevented the acidification of phagosomes. These results indicated that virulent isolates of H. somni were capable of surviving within phagocytic cells through interference in phagosome-lysosome maturation. Therefore, H. somni may be considered a permissive intracellular pathogen.
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Domenech M, Pedrero-Vega E, Prieto A, García E. Evidence of the presence of nucleic acids and β-glucan in the matrix of non-typeable Haemophilus influenzae in vitro biofilms. Sci Rep 2016; 6:36424. [PMID: 27805043 PMCID: PMC5090351 DOI: 10.1038/srep36424] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 10/14/2016] [Indexed: 12/21/2022] Open
Abstract
Non-typeable Haemophilus influenzae (NTHi) is a Gram-negative bacterium that frequently colonizes the human nasopharynx; it is a common cause of chronic and recurrent otitis media in children and of exacerbations of chronic obstructive pulmonary disease. To date, no exopolysaccharide clearly contributing to NTHi biofilms has been identified. Consequently, there is some debate as to whether NTHi forms biofilms during colonization and infection. The present work shows that NTHi can form biofilms in vitro, producing an extracellular matrix composed of proteins, nucleic acids, and a β-glucan. Extracellular DNA, visualized by immunostaining and using fluorochromes, is an important component of this matrix and appears to be essential in biofilm maintenance. Extracellular RNA appears to be required only in the first steps of biofilm formation. Evidence of a matrix polysaccharide was obtained by staining with Calcofluor white M2R and by disaggregating biofilms with cellulase. Using strain 54997, residues of Glcp(1→4) in the NTHi biofilm were confirmed by gas-liquid chromatography-mass spectrometry. Evidence that N-acetyl-L-cysteine shows notable killing activity towards in vitro NTHi biofilm-forming bacteria is also provided.
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Affiliation(s)
- Mirian Domenech
- Departamento de Microbiología Molecular y Biología de las Infecciones, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
- CIBER de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, Monforte de Lemos 3–5, 28029 Madrid, Spain
| | - Elena Pedrero-Vega
- Departamento de Microbiología Molecular y Biología de las Infecciones, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Alicia Prieto
- Departamento de Biología Medioambiental, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Ernesto García
- Departamento de Microbiología Molecular y Biología de las Infecciones, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
- CIBER de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, Monforte de Lemos 3–5, 28029 Madrid, Spain
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