Examination of surface polysaccharides of Actinobacillus pleuropneumoniae serotype 1 grown under iron-restricted conditions.
We investigated the expression of important Actinobacillus pleuropneumoniae surface polysaccharides, namely, capsular polysaccharides (CPS) and lipopolysaccharides (LPS), after growth under iron-restricted conditions. Iron restriction did not seem to affect the production of CPS, as determined by labelling with a monoclonal antibody (mAb) against the serotype 1 K-antigen and flow cytometry analysis, and also as determined by electron microscopy. SDS-PAGE revealed that the LPS profiles of these cells were also unaffected by iron restriction. Using flow cytometry analysis, however, we observed that binding of mAb against serotype 1 O-antigen was altered in cells of A. pleuropneumoniae serotype 1 reference strain (4074) grown under iron-restricted conditions. This strain exhibited two subpopulations with distinct patterns of reactivity with the mAb against the O-antigen. When strain 4074 was grown under iron-restricted conditions, a shift from one cell subpopulation (moderately fluorescent) to another cell subpopulation (highly fluorescent, thus binding more antibodies) was observed. Our results indicate that growth of A. pleuropneumoniae serotype 1 under iron-restricted conditions did not seem to affect CPS production, but might alter, at least for the reference strain, the expression of LPS.
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Département de pathologie et microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, Québec, Canada.
Dubreuil
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Jacques
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D016977:Actinobacillus pleuropneumoniae / Q000145:classification / Q000254:growth & development / Q000378:metabolism*; D000911:Antibodies, Monoclonal; D016667:Bacterial Capsules / Q000096:biosynthesis / Q000276:immunology; D005434:Flow Cytometry; D007501:Iron / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000096:biosynthesis / Q000276:immunology; D016253:Microscopy, Immunoelectron; D019081:O Antigens / Q000096:biosynthesis; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000276:immunology; D012703:Serotyping
D000911:Antibodies, Monoclonal; D008070:Lipopolysaccharides; D019081:O Antigens; D011135:Polysaccharides, Bacterial; D007501:Iron