title: Immunogenicity of Actinobacillus pleuropneumoniae outer membrane proteins and enhancement of phagocytosis by antibodies to the proteins.
abstract: To determine the opsonic effect of antibodies to Actinobacillus (Haemophilus) pleuropneumoniae outer membrane proteins on phagocytosis by porcine polymorphonuclear leukocytes (PMN), we separated the integral outer membrane proteins (IOMPs) by Triton X-114 extraction. Four major IOMPs with molecular masses of 76, 50, 39, and 29 kDa were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These IOMPs were found to be essentially free of endotoxin in the Limulus amebocyte lysate assay. The 76-kDa protein exhibited a more intensely stained electrophoresis band when isolated from iron-restricted cultures, and a new band at 105 kDa was present in the whole-membrane fraction but not in the integral fraction, indicating that the 105-kDa iron-repressible protein is a peripheral membrane protein. The 76-, 50-, and 39-kDa proteins were shown to be surface exposed, since antibodies to these IOMPs could be absorbed out of convalescent-phase sera by whole cells. Percentages of phagocytosis by porcine PMN of A. pleuropneumoniae opsonized with convalescent-phase sera, convalescent-phase sera absorbed with IOMPs, or convalescent-phase sera absorbed with whole cells were 46.75, 21.81, and 7.96%, respectively. These results demonstrate that antibodies to IOMPs of A. pleuropneumoniae serve as important opsonins in phagocytosis by porcine PMN.
authors.affiliation: Department of Medical Microbiology, College of Veterinary Medicine, University of Georgia, Athens 30602.
authors.forename: R N
authors.initials: RN
authors.lastname: Thwaits
authors.forename: S
authors.initials: S
authors.lastname: Kadis
mesh_terms: D000188:Actinobacillus / Q000276:immunology* / Q000472:pathogenicity; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology*; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology* / Q000302:isolation & purification; D015151:Immunoblotting; D009504:Neutrophils / Q000276:immunology; D010587:Phagocytosis; D013552:Swine
chemical_list: D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins