ABSTRACT
Actinobacillus pleuropneumoniae has been considered nonmotile and nonflagellate. In this work, it is demonstrated that A. pleuropneumoniae produces flagella composed of a 65-kDa protein with an N-terminal amino acid sequence that shows 100% identity with those of Escherichia coli, Salmonella, and Shigella flagellins. The DNA sequence obtained through PCR of the fliC gene in A. pleuropneumoniae showed considerable identity (93%) in its 5' and 3' ends with the DNA sequences of corresponding genes in E. coli, Salmonella enterica, and Shigella spp. The motility of A. pleuropneumoniae was observed in tryptic soy or brain heart infusion soft agar media, and it is influenced by temperature. Flagella and motility may be involved in the survival and pathogenesis of A. pleuropneumoniae in pigs.
Subject(s)
Actinobacillus pleuropneumoniae/physiology , Flagella/metabolism , Flagella/ultrastructure , Actinobacillus Infections/veterinary , Actinobacillus pleuropneumoniae/genetics , Actinobacillus pleuropneumoniae/ultrastructure , Animals , Culture Media , Flagellin/chemistry , Flagellin/genetics , Flagellin/metabolism , Microscopy, Electron , Molecular Sequence Data , Movement , Sequence Analysis, DNA , Swine , Swine Diseases/microbiologyABSTRACT
Actinobacillus pleuropneumoniae serotype 1 releases vesicles containing proteases and Apx toxins into the culture medium. Vesicles were concentrated by ultracentrifugation and analyzed by electron microscopy and electrophoresis; their size ranged from 20 to 200 nm. A polyclonal antiserum raised against a purified high molecular mass secreted protease of serotype 1 recognized this protease on the surface of the vesicles by immunogold electron microscopy. Higher molecular mass polypeptides from vesicle extracts were recognized by the antiserum by Western immunoblot, indicating that the protease could form oligomers. However, these oligomers were not active against gelatin until secreted. Additionally, Apx toxins were also present in vesicles, and were recognized by Western immunoblot by an anti-serotype 1 toxins polyclonal serum. A. pleuropneumoniae antigens in vesicles were recognized by convalescent-phase pig sera from animals infected with serotype 1 or 5. The release of vesicles containing virulence factors could be a tissue damage mechanism in swine pleuropneumonia.
Subject(s)
Actinobacillus pleuropneumoniae/metabolism , Bacterial Toxins/metabolism , Endopeptidases/metabolism , Transport Vesicles/metabolism , Actinobacillus pleuropneumoniae/growth & development , Actinobacillus pleuropneumoniae/ultrastructure , Electrophoresis, Polyacrylamide Gel , Immunoblotting , Microscopy, Electron , Transport Vesicles/ultrastructure , UltracentrifugationABSTRACT
Foi isolada uma amostra de A. pleuropneumoniae sorotipo 3, de suínos originados de um sistema de criaçäo de multiplicaçäo de material genético melhorado. Esta amostra é fracamente hemolítica para hemáceas de cavalo em ágar sangue, fermentadora da rafinose e "CAMP-test" negativa. Foi isolada de pequenos abscessos disseminados pelo parênquima pulmonar e, quando inoculada em animais SPF, induziu lesöes clássicas de pleuropneumonia suína e näo induziu anticorpos neutralizantes da hemólise para as citolisinas I e II