title: Immunochemical analysis and possible biological role of an Aeromonas hydrophila surface array protein in septicaemia.
abstract: The biochemical, immunological, and biological properties of an S layer purified from an Aeromonas hydrophila strain (AH-342) involved in a case of bacteraemia were investigated. The S layer selectively removed from the cell surface was composed of a single acidic (pI 4.56) protein subunit (surface array protein, SAP) with a molecular mass of approximately 52 kDa. Amino acid analysis of this 52 kDa protein indicated a molecule composed of 498 amino acids with 46% hydrophobic residues. No cysteine residues were detected. The first 35 residues of the N-terminus were sequenced by Edman degradation; only 4-24% homology was noted between this sequence and those previously published for SAPs of Aeromonas salmonicida (A450) and a strain of A. hydrophila (TF7) originally isolated from a moribund fish. Polyclonal antibodies raised against AH-342 SAP were genospecific, reacting only against S layers produced by A. hydrophila strains and not those from Aeromonas veronii. Acute serum from the bacteraemic patient from whom AH-342 was isolated reacted strongly with the SAP of AH-342 in immunoblot studies. Purified SAP, when intraperitoneally co-inoculated with SAP- strains of A. hydrophila into Swiss-Webster mice, could reduce the 50% lethal dose by approximately 30-70 fold. The results suggest that the SAP of A. hydrophila strains may play an important role in systemic dissemination after invasion through the gastrointestinal mucosa.
authors.affiliation: Microbial Diseases Laboratory, California Department of Health Services, Berkeley 94704-1011.
authors.forename: R P
authors.initials: RP
authors.lastname: Kokka
authors.forename: N A
authors.initials: NA
authors.lastname: Vedros
authors.forename: J M
authors.initials: JM
authors.lastname: Janda
mesh_terms: D016980:Aeromonas hydrophila / Q000145:classification / Q000276:immunology / Q000472:pathogenicity*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D001426:Bacterial Proteins; D016905:Gram-Negative Bacterial Infections / Q000209:etiology* / Q000276:immunology / Q000378:metabolism; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D019081:O Antigens; D011135:Polysaccharides, Bacterial / Q000276:immunology; D018805:Sepsis / Q000209:etiology* / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D014774:Virulence / Q000276:immunology
chemical_list: D000596:Amino Acids; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D016056:Immunodominant Epitopes; D008562:Membrane Glycoproteins; D019081:O Antigens; D011135:Polysaccharides, Bacterial; C055764:S-layer proteins