Dataset Information

Pathology of experimentally induced mouthrot caused by Tenacibaculum maritimum in Atlantic salmon smolts.

ABSTRACT: Mouthrot, caused by Tenacibaculum maritimum is a significant disease of farmed Atlantic salmon, Salmo salar on the West Coast of North America. Smolts recently transferred into saltwater are the most susceptible and affected fish die with little internal or external clinical signs other than the characteristic small (usually < 5 mm) yellow plaques that are present inside the mouth. The mechanism by which these smolts die is unknown. This study investigated the microscopic pathology (histology and scanning electron microscopy) of bath infected smolts with Western Canadian T. maritimum isolates TmarCan15-1, TmarCan16-1 and TmarCan16-5 and compared the findings to what is seen in a natural outbreak of mouthrot. A real-time RT-PCR assay based on the outer membrane protein A specific for T. maritimum was designed and used to investigate the tissue tropism of the bacteria. The results from this showed that T. maritimum is detectable internally by real-time RT-PCR. This combined with the fact that the bacteria can be isolated from the kidney suggests that T. maritimum becomes systemic. The pathology in the infected smolts is primarily mouth lesions, including damaged tissues surrounding the teeth; the disease is similar to periodontal disease in mammals. The pathological changes are focal, severe, and occur very rapidly with little associated inflammation. Skin lesions are more common in experimentally infected smolts than in natural outbreaks, but this could be an artefact of the challenge dose, handling and tank used during the experiments.

SUBMITTER: Frisch K

PROVIDER: S-EPMC6211739 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Pathology of experimentally induced mouthrot caused by Tenacibaculum maritimum in Atlantic salmon smolts.

Frisch Kathleen K Småge Sverre Bang SB Johansen Renate R Duesund Henrik H Brevik Øyvind Jakobsen ØJ Nylund Are A

PloS one 20181101 11

Mouthrot, caused by Tenacibaculum maritimum is a significant disease of farmed Atlantic salmon, Salmo salar on the West Coast of North America. Smolts recently transferred into saltwater are the most susceptible and affected fish die with little internal or external clinical signs other than the characteristic small (usually < 5 mm) yellow plaques that are present inside the mouth. The mechanism by which these smolts die is unknown. This study investigated the microscopic pathology (histology an ...[more]

PMID: 30383870

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Project description:Tenacibaculum maritimum, the etiological agent of tenacibaculosis in marine fish, constitutively secretes extracellular products (ECPs), which play a main role in virulence. However, their protein content has not been yet comprehensively studied. In this study a collection of 64 T. maritimum strains belonging to the four serotypes described so far (O1 to O4) was used to analyse the prevalence of extracellular proteolytic and lipolytic activities related to virulence. Results showed the existence of a large heterogeneity of the enzymatic capacity among serotype O4 isolates. Most notably, the ECPs of T. maritimum SP9.1 belonging to serotype O4 contain a large amount of outer membrane vesicles (OMVs), which were characterized by electron microscopy and purified by successive steps of filtration and centrifugation. Total protein content of ECPs, and the proteins associated to OMVs and soluble fraction of the ECPs (S-ECPs) were identified by nLC-TIMS-QTOF. A total of 641 proteins were identified in ECPs including some virulence related factors, which were mainly found in one of the fractions, either in OMVs or S-ECPs. Outer membrane proteins such as TonB-dependent transporters and the T9SS-related proteins PorP, PorT and SprA appeared to be mainly associated with OMVs. By contrast, putative virulence factors such as sialidase SiaA, chondroitinase CslA, sphingomyelinase Sph, ceramidase Cer and collagenase Col were found only in the S-ECPs. These findings demonstrate that T. maritimum release, through surface blebbing, outer membrane vesicles that are enriched specifically in TonB-dependent siderophore transporters and proteins of the type IX secretion system. Interestingly, our results also showed that OMVs could play a role in virulence by promoting surface adhesion, biofilm formation, and maximizing cytotoxic effects of the ECPs. The T. maritimum secretome analysis provides insights into the extracellular products function and can constitute the basis for future studies aimed to elucidate the role of OMVs in the pathogenesis of fish tenacibaculosis.

Dataset Information

Pathology of experimentally induced mouthrot caused by Tenacibaculum maritimum in Atlantic salmon smolts.

Publications

Pathology of experimentally induced mouthrot caused by Tenacibaculum maritimum in Atlantic salmon smolts.

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