Protective Immune Response Is Generated in Rainbow Trout by an OmpH-Like Surface Antigen (P18) of Flavobacterium psychrophilum

• Published in: Applied and Environmental Microbiology 2006-07, Vol.72 (7), p.4845-4852
• Main Authors: Dumetz, Fabien, Duchaud, Eric, LaPatra, Scott E, Le Marrec, Claire, Claverol, Stéphane, Urdaci, Maria-C, Le Hénaff, Michel
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequences; Animals; antibacterial properties; Antibodies, Bacterial - blood; antibody formation; bacterial antigens; Bacterial Outer Membrane Proteins - chemistry; Bacterial Outer Membrane Proteins - genetics; Bacterial Outer Membrane Proteins - immunology; Bacterial Outer Membrane Proteins - isolation & purification; Bacterial Vaccines - administration & dosage; Bacterial Vaccines - immunology; Biological and medical sciences; Brackish; Fish Diseases - immunology; Fish Diseases - prevention & control; Flavobacteriaceae Infections - immunology; Flavobacteriaceae Infections - prevention & control; Flavobacteriaceae Infections - veterinary; Flavobacterium - immunology; Flavobacterium psychrophilum; Freshwater; Fundamental and applied biological sciences. Psychology; genes; Life Sciences; Marine; Microbiology; Microbiology and Parasitology; Molecular Sequence Data; nucleotide sequences; ompH gene; ompH locus; Oncorhynchus mykiss; Oncorhynchus mykiss - immunology; outer membrane proteins; P18 protein; Physiology and Biotechnology; purification; Sequence Analysis, DNA; surface antigens; vaccination; Vaccination - veterinary; vaccine development
• ISSN: 0099-2240; 1364-5072; 1098-5336; 1365-2672
• DOI: 10.1128/AEM.00279-06

Investigations of the surface characteristics of Flavobacterium psychrophilum, an important pathogen of fish, assisted us in identifying a surface protein termed P18. In the current study, we developed a simple and efficient procedure for the purification of this protein by a two-step method. First, P18 was selectively released from flavobacteria by a heat-HEPES treatment of the cells and then subjected to anion-exchange high-performance liquid chromatography. De novo sequencing was used to generate a fragmented peptide spectrum from purified P18. Comparison of two obtained peptide sequences with a partial genome sequence of F. psychrophilum (INRA, Jouy-en-Josas, France) identified one gene encoding a 166-amino-acid OmpH-like protein that mostly likely undergoes N-terminal cleavage of the 23-residue signal peptide. The susceptibility of the OmpH-like protein to proteinase K treatment and the bacteriostatic/bactericidal activities of anti-OmpH-like protein antibodies indicated that this protein is actually exposed on the surface of F. psychrophilum. Vaccination trials showed that the OmpH-like protein can induce a high titer of anti-OmpH-like protein antibodies which are protective. Taken together, these results suggest that this surface protein produced by F. psychrophilum could be used in future vaccine development as a promising candidate antigen.