VtaA8 and VtaA9 from Haemophilus parasuis delay phagocytosis by alveolar macrophages
Open Access
- 27 July 2012
- journal article
- Published by Springer Science and Business Media LLC in Veterinary Research
- Vol. 43 (1), 57
- https://doi.org/10.1186/1297-9716-43-57
Abstract
Haemophilus parasuis, a member of the family Pasteurellaceae, is a common inhabitant of the upper respiratory tract of healthy pigs and the etiological agent of Glässer’s disease. As other virulent Pasteurellaceae, H. parasuis can prevent phagocytosis, but the bacterial factors involved in this virulence mechanism are not known. In order to identify genes involved in phagocytosis resistance, we constructed a genomic library of the highly virulent reference strain Nagasaki and clones were selected by increased survival after incubation with porcine alveolar macrophages (PAM). Two clones containing two virulent-associated trimeric autotransporter (VtaA) genes, vtaA8 and vtaA9, respectively, were selected by this method. A reduction in the interaction of the two clones with the macrophages was detected by flow cytometry. Monoclonal antibodies were produced and used to demonstrate the presence of these proteins on the bacterial surface of the corresponding clone, and on the H. parasuis phagocytosis-resistant strain PC4-6P. The effect of VtaA8 and VtaA9 in the trafficking of the bacteria through the endocytic pathway was examined by fluorescence microscopy and a delay was detected in the localization of the vtaA8 and vtaA9 clones in acidic compartments. These results are compatible with a partial inhibition of the routing of the bacteria via the degradative phagosome. Finally, antibodies against a common epitope in VtaA8 and VtaA9 were opsonic and promoted phagocytosis of the phagocytosis-resistant strain PC4-6P by PAM. Taken together, these results indicate that VtaA8 and VtaA9 are surface proteins that play a role in phagocytosis resistance of H. parasuis.Keywords
This publication has 32 references indexed in Scilit:
- Cytolethal distending toxin (CDT) of the Haemophilus parasuis SC096 strain contributes to serum resistance and adherence to and invasion of PK-15 and PUVEC cellsVeterinary Microbiology, 2012
- Immunogenicity and protection against Haemophilus parasuis infection after vaccination with recombinant virulence associated trimeric autotransporters (VtaA)Vaccine, 2011
- Virulence-associated trimeric autotransporters ofHaemophilus parasuisare antigenic proteins expressed in vivoVeterinary Research, 2009
- Differences in phagocytosis susceptibility inHaemophilus parasuisstrainsVeterinary Research, 2009
- Localization of the Domains of the Haemophilus ducreyi Trimeric Autotransporter DsrA Involved in Serum Resistance and Binding to the Extracellular Matrix Proteins Fibronectin and VitronectinInfection and Immunity, 2009
- Trimeric Autotransporters ofHaemophilus parasuis: Generation of an Extensive Passenger Domain Repertoire Specific for Pathogenic StrainsJournal of Bacteriology, 2009
- Meningococcal Outer Membrane Protein NhhA Is Essential for Colonization and Disease by Preventing Phagocytosis and Complement AttackInfection and Immunity, 2008
- Immunization with Recombinant Sao Protein Confers Protection against Streptococcus suis InfectionClinical and Vaccine Immunology, 2007
- MECHANISMS OF PHAGOCYTOSIS IN MACROPHAGESAnnual Review of Immunology, 1999
- Production of Monoclonal Antibodies to SalinomycinHybridoma, 1986