ABSTRACT
AIMS: Moritella viscosa is a Gram-negative psychrophilic bacterium that causes winter ulcer disease in farmed fish. The aim of the study was to describe an outer membrane protein of roughly 20 kDa in pathogenic M. viscosa and to compare the coincident protein of strains isolated from different fish species and geographical locations. METHODS AND RESULTS: The protein was isolated from a pathogenic strain of M. viscosa. An oligopeptide sequence obtained with MS/MS analysis showed homology to Escherichia coli OmpA and Neisseria surface protein A. The protein was named Moritella viscosa outer membrane protein 1 (MvOmp1), and sequence analysis confirmed that it is an integral membrane protein consisting of eight antiparallel ß-strands, three short periplasmic turns and four long hydrophilic extracellular loops. The encoding gene, mvomp1, was fully sequenced in nine strains representing different serotypes and phenotypes. The results revealed some differences in the extracellular loops between strains. The mvomp1 gene was cloned and expressed in E. coli, and the recombinant product was recognized by anti-M. viscosa polyclonal antisera. CONCLUSIONS: The results indicate that MvOmp1 is a major protective antigen of M. viscosa. SIGNIFICANCE AND IMPACT OF THE STUDY: The results open up possibilities for use of the protein as a part of a subunit vaccine in the future.
Subject(s)
Antigens, Bacterial/immunology , Bacterial Outer Membrane Proteins/immunology , Fish Diseases/microbiology , Gram-Negative Bacterial Infections/veterinary , Moritella/immunology , Amino Acid Sequence , Animals , Antigens, Bacterial/chemistry , Antigens, Bacterial/genetics , Bacterial Outer Membrane Proteins/chemistry , Bacterial Outer Membrane Proteins/genetics , Fish Diseases/immunology , Fish Diseases/pathology , Fishes , Gram-Negative Bacterial Infections/immunology , Gram-Negative Bacterial Infections/microbiology , Gram-Negative Bacterial Infections/pathology , Molecular Sequence Data , Sequence AlignmentABSTRACT
An assay based on reverse transcription and nested PCR amplification of hypervariable regions within the 16S rRNA sequence was used to specifically detect Renibacterium salmoninarum, the slowly growing causative agent of bacterial kidney disease in salmonid fish. This assay detected 1 to 10 bacteria per sample and took 1 to 2 days to perform. The assay was used to detect R. salmoninarum in ovarian fluid obtained from naturally infected fish. The assay was unreliable when it was used to examine kidney tissue.
Subject(s)
Fish Diseases/microbiology , Gram-Positive Bacteria/isolation & purification , Gram-Positive Bacterial Infections/veterinary , Kidney Diseases/veterinary , Polymerase Chain Reaction/methods , Salmon/microbiology , Animals , Base Sequence , Cloning, Molecular , Female , Genes, Bacterial/genetics , Gram-Positive Bacteria/genetics , Gram-Positive Bacterial Infections/microbiology , Kidney/microbiology , Kidney Diseases/microbiology , Molecular Sequence Data , Ovary/microbiology , RNA, Ribosomal, 16S/genetics , RNA-Directed DNA Polymerase , Sensitivity and SpecificityABSTRACT
Rhodothermus marinus, a gram-negative heterotrophic marine thermophile, has been the subject of several recent studies. Isolation, sequencing, and analyses of a 16S rRNA gene have shown that R. marinus diverges sharply from major bacterial phyla and is most closely allied to the Flexibacter-Cytophaga-Bacteroides group. Further analyses revealed that the R. marinus chromosome contains a single rRNA operon with a 16S-23S intergenic region coding for tRNA(Ile) and tRNA(Ala).
