Differences in phagocytosis susceptibility in Haemophilus parasuis strains

Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
Veterinary Research (Impact Factor: 2.82). 03/2009; 40(3):24. DOI: 10.1051/vetres/2009007
Source: PubMed


Haemophilus parasuis is a colonizer of the upper respiratory tract of healthy pigs, but virulent strains can cause a systemic infection characterized by fibrinous polyserositis, commonly known as Glässer's disease. The variability in virulence that is observed among H. parasuis strains is not completely understood, since the virulence mechanisms of H. parasuis are largely unknown. In the course of infection, H. parasuis has to survive the host pulmonary defences, which include alveolar macrophages, to produce disease. Using strains from different clinical backgrounds, we were able to detect clear differences in susceptibility to phagocytosis. Strains isolated from the nose of healthy animals were efficiently phagocytosed by porcine alveolar macrophages (PAM), while strains isolated from systemic lesions were resistant to this interaction. Phagocytosis of susceptible strains proceeded through mechanisms independent of a specific receptor, which involved actin filaments and microtubules. In all the systemic strains tested in this study, we observed a distinct capsule after interaction with PAM, indicating a role of this surface structure in phagocytosis resistance. However, additional mechanisms of resistance to phagocytosis should be explored, since we detected different effects of microtubule inhibition among systemic strains.

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Available from: Miquel Nofrarías
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    • "Several virulence factors contributing to the pathogenesis of Glässer’s disease have been reported in virulent strains, including lipooligosaccharide [8], polysaccharide biosynthesis protein [9], outer membrane protein P2 [10], cytolethal distending toxin [11,12], extracellular serine protease [13], autotransporters [14,15], capsule [16], hemolysin [17], sialylation [18], UDP-glucose pyrophosphorylase, and UDP-glucose 4′-epimerase [19]. Meanwhile, many of them can also be detected in avirulent strains. "
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    ABSTRACT: Background Haemophilus parasuis is the causative agent of Glässer’s disease characterized by polyserositis, arthritis, and meningitis in pig, leading to serious economic loss. Despite many years of study, virulence factors and the mechanisms of the entire infection process remain largely unclear. So two-dimensional gel electrophoresis and mass spectrometry were used to search for distinctions at the membrane protein expression level between two H. parasuis isolates aimed at uncovering some proteins potentially involved in habitat adaption and pathogenesis. Results A comparative proteomic approach combining two-dimensional gel electrophoresis with mass spectrometry and tandem mass spectrometry was employed to explore the differences among membrane proteomes of a virulent Haemophilus parasuis strain isolated from the lung of a diseased pig and an avirulent strain isolated from the nasal swab of a healthy pig. Differentially expressed protein spots identified by mass spectrometry were annotated and analyzed by bioinformatic interpretation. The mRNA level was determined by quantitative real-time PCR. Proteins representing diverse functional activities were identified. Among them, the tonB-dependent siderophore receptor was a new discovery highlighted for its activity in iron uptake. In addition, periplasmic serine protease and putrescine/spermidine ABC transporter substrate-binding protein were given focus because of their virulence potential. This study revealed that the differentially expressed proteins were important in either the habitat adaption or pathogenesis of H. parasuis. Conclusions The outcome demonstrated the presence of some proteins which raise the speculation for their importance in helping in habitat adaption or pathogenesis within the host.
    Full-text · Article · Jul 2014 · Proteome Science
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    • "From the upper respiratory tract, H. parasuis proceeds to the lung (Vahle et al., 1997), where it encounters a line of defense constituted by alveolar macrophages. It is known that virulent strains are resistant to macrophage phagocytosis in vitro (Olvera et al., 2009), but the interaction between H. parasuis and macrophages or other cells in the lung is not well determined. Thus, the objective of the present study was to explore how H. parasuis strains of different virulence interact with the respiratory tract of pigs during infection. "
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    ABSTRACT: Haemophilus parasuis is a common inhabitant of the upper respiratory tract of pigs and the etiological agent of Glässer's disease. However, the host-pathogen interaction remains to be well understood. In this work, 33 colostrum-deprived pigs were divided in 4 groups and each group was inoculated intranasally with a different H. parasuis strain (non-virulent strains SW114 and F9, and virulent strains Nagasaki and IT29755). Animals were necropsied at different times in order to determine the location of the bacteria in the respiratory tract of the host during infection. An immunohistochemistry method was developed to detect H. parasuis in nasal turbinates, trachea and lung. Also, the co-localization of H. parasuis with macrophages or neutrophils was examined by double immunohistochemistry and double immunofluorescence. Virulent strains showed a biofilm-like growth in nasal turbinates and trachea and were found easily in lung. Some virulent bacteria were detected in association with macrophages and neutrophils, but also inside pneumocyte-like cells. On the other hand, non-virulent strains were seldom detected in nasal turbinates and trachea, where they showed a microcolony pattern. Non-virulent strains were essentially not detected in lung. In conclusion, this work presents data showing differential localization of H. parasuis bacteria depending on their virulence. Interestingly, the intracellular location of virulent H. parasuis bacteria in non-phagocytic cells in lung could allow the persistence of the bacteria and constitute a virulence mechanism.
    Full-text · Article · Jun 2014 · Veterinary Microbiology
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    • "Based on epidemiological and experimental data some serovars (i.e., 1, 2, 4, 5, 12, 13, and 14) are thought to have greater virulence potential than others; however, within serovar variation has been reported (Angen et al., 2004; Rapp-Gabrielson et al., 2006). A number of virulence factors have been associated with the pathogenesis of Glä sser's disease, including capsule (Olvera et al., 2009), lipooligosacharides (Xu et al., 2013), specific outer membrane proteins (Zhang et al., 2012a), haemolysin (Sack and Baltes, 2009), "
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    ABSTRACT: A collection of 94 Haemophilus parasuis isolates was used for this study. It consisted of isolates from organs of pigs with Glässer's disease and pneumonia (n=54), from nasal swabs of healthy pigs in farms without Glässer's disease problems (n=25), and 15 reference strains. These isolates were typed using a new multilocus variable number of tandem repeats analysis (MLVA) protocol and investigated for the presence of nine putative virulence genes. The new MLVA protocol was highly discriminatory (54 types identified and discrimination index of 97.4%) and reproducible. Similar to previous investigations done with other methods, two major genetic clusters were identified by MLVA, which partially correlated with serotype and virulence gene distributions. Gene linkage analysis suggested that lateral gene transfer occurs within each of these clusters, but rarely between them. Although one single MLVA type included more than 20% of the clinical isolates, no significant correlation was detected between a specific MLVA type, the major genetic clusters, or the presence of any of the virulence genes investigated or the source of the isolates (clinical infection vs. healthy pig). The MLVA typing protocol described in this study is a promising new tool for future investigations into the epidemiology of Glässer's disease and could help us to better understand interacting microbial, host and environmental factors that lead to the development of H. parasuis disease.
    Full-text · Article · Aug 2013 · Veterinary Microbiology
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