title: Clinical isolates of Aeromonas veronii biovar veronii harbor a nonfunctional gene similar to the thermostable direct hemolysin-related hemolysin (trh) gene of Vibrio parahaemolyticus.
abstract: Thermostable direct hemolysin-related hemolysin encoded by the trh gene is considered a major virulence factor in the pathogenesis of Vibrio parahaemolyticus infections. In this study, we report the presence of a trh homolog in three clinical isolates of Aeromonas veronii biovar veronii. The presence of a trh homolog in these strains of A. veronii was confirmed by PCR, followed by cloning, sequencing and colony hybridization using a digoxigenin-labelled probe. DNA sequence analysis revealed that the A. veronii trh gene had an identity of 99% and 84% to the trh1 and trh2 genes of V. parahaemolyticus, respectively. However, the expression of a trh-like gene in A. veronii could not be detected by reverse transcription PCR. Hence, the role of the gene product in the virulence of A. veronii strains is not clear. Further, these A. veronii isolates were negative for the ure gene encoding urease and the transposase gene by PCR. These genes are part of the trh gene cluster in V. parahaemolyticus. However, the presence of a trh homolog in a pathogen other than V. parahaemolyticus points to the fact that detection of the trh gene in stool samples, seafood enrichments or environmental samples does not always imply that trh-carrying V. parahaemolyticus are present.
authors.affiliation: Department of Fishery Microbiology, College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Mangalore, India.
authors.forename: Pendru
authors.initials: P
authors.lastname: Raghunath
authors.forename: Biswajit
authors.initials: B
authors.lastname: Maiti
authors.forename: Malathi
authors.initials: M
authors.lastname: Shekar
authors.forename: Iddya
authors.initials: I
authors.lastname: Karunasagar
authors.forename: Indrani
authors.initials: I
authors.lastname: Karunasagar
mesh_terms: D000333:Aeromonas / Q000235:genetics* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015153:Blotting, Western; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006460:Hemolysin Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D006460:Hemolysin Proteins; C088609:thermostable direct hemolysin-related hemolysin protein, Vibrio parahaemolyticus