Comparative susceptibility of Atlantic salmon and rainbow trout to Yersinia ruckeri: Relationship to O antigen serotype and resistance to serum killing

AbstractYersinia ruckeri is the causative agent of enteric redmouth disease (ERM) which causes economically significant losses in farmed salmonids, especially Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss, Walbaum). However, very little is known about the genetic relationships of disease-causing isolates in these two host species or about factors responsible for disease. Phylogenetic analyses of 16 representative isolates based on the nucleotide sequences of 19 housekeeping genes suggests that pathogenic Atlantic salmon and rainbow trout isolates represent distinct host-specific lineages. However, the apparent phylogenies of certain isolates has been influenced by horizontal gene transfer and recombinational exchange. Splits decomposition analysis demonstrated a net-like phylogeny based on the housekeeping genes, characteristic of recombination. Comparative analysis of the distribution of individual housekeeping gene alleles across the isolates demonstrated evidence of genomic mosaicism and recombinational exchange involving certain Atlantic salmon and rainbow trout isolates. Comparative nucleotide sequence analysis of the key outer membrane protein genes ompA and ompF revealed that the corresponding gene trees were both non-congruent with respect to the housekeeping gene phylogenies providing evidence that horizontal gene transfer has influenced the evolution of both these surface protein-encoding genes. Analysis of inferred amino acid sequence variation in OmpA identified a single variant, OmpA.1, that was present in serotype O1 and O8 isolates representing typical pathogenic strains in rainbow trout and Atlantic salmon, respectively. In particular, the sequence of surface-exposed loop 3 differed by seven amino acids to that of other Y. ruckeri isolates. These findings suggest that positive selection has likely influenced the presence of OmpA.1 in these isolates and that loop 3 may play an important role in virulence. Amino acid sequence variation of OmpF was greater than that of OmpA and was similarly restricted mainly to the surface-exposed loops. Two OmpF variants, OmpF.1 and OmpF.2, were associated with pathogenic rainbow trout and Atlantic salmon isolates, respectively. These OmpF proteins had very similar amino acid sequences suggesting that positive evolutionary pressure has also favoured the selection of these variants in pathogenic strains infecting both species.

Download Full-text

Plaque-Forming Cells and Humoral Antibody in Rainbow Trout (Salmo gairdneri) Induced by Immersion in a Yersinia ruckeri O-Antigen Preparation

Journal of the Fisheries Research Board of Canada ◽

10.1139/f79-092 ◽

1979 ◽

Vol 36 (6) ◽

pp. 636-639 ◽

Cited By ~ 27

Author(s):

D. P. Anderson ◽

B. S. Roberson ◽

O. W. Dixon

Keyword(s):

Rainbow Trout ◽

Plaque Assay ◽

Control Fish ◽

Salmo Gairdneri ◽

Yersinia Ruckeri ◽

Passive Hemagglutination ◽

Humoral Antibody ◽

O Antigen ◽

Significant Difference ◽

Antibody Titers

Rainbow trout (Salmo gairdneri) were exposed to the O-antigen of Yersinia ruckeri by various immunization regimens. The passive hemolytic plaque assay was used to show specific splenic plaque-forming cells (PFC) and passive hemagglutination demonstrated humoral antibody titers in fish injected with or immersed in the antigen preparations. Preceding antigen immersion with a 2-min immersion in either a 5.2 or a 2.6% NaCl solution did not affect the numbers of PFC or levels of antibody. Fish held for 2 min in ethyl m-aminobenzoate methanesulfonate (MS-222®) before antigen immersion showed no significant difference from the control fish. Dosage studies showed that the minimal concentration of antigen for induction of PFC by immersion was 5.0 μg/mL. Key words: plaque-forming cells, immunization, rainbow trout immersion, Yersinia ruckeri

Download Full-text

Cellular immune response in rainbow trout Salmo gairdneri Richardson to Yersinia ruckeri O-antigen monitored by the passive haemolytic plaque assay test

Journal of Fish Diseases ◽

10.1111/j.1365-2761.1979.tb00156.x ◽

1979 ◽

Vol 2 (3) ◽

pp. 169-178 ◽

Cited By ~ 28

Author(s):

D. P. ANDERSON ◽

B. S. ROBERTSON ◽

O. W. DIXON

Keyword(s):

Immune Response ◽

Rainbow Trout ◽

Cellular Immune Response ◽

Plaque Assay ◽

Salmo Gairdneri ◽

Yersinia Ruckeri ◽

O Antigen ◽

Cellular Immune

Download Full-text

Vibrio anguillarum Resistance to Rainbow Trout (Oncorhynchus mykiss) Serum: Role of O-Antigen Structure of Lipopolysaccharide

Infection and Immunity ◽

10.1128/iai.67.1.294-301.1999 ◽

1999 ◽

Vol 67 (1) ◽

pp. 294-301 ◽

Cited By ~ 61

Author(s):

Henriette T. Boesen ◽

Karl Pedersen ◽

Jens L. Larsen ◽

Claus Koch ◽

Anthony E. Ellis

Keyword(s):

Molecular Weight ◽

Rainbow Trout ◽

High Molecular Weight ◽

Vibrio Anguillarum ◽

Bactericidal Effect ◽

Specific Antibodies ◽

Classical Complement Pathway ◽

O Antigen ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Serum Killing

ABSTRACT The sensitivity of Vibrio anguillarum to the bactericidal effect of rainbow trout serum was investigated with different strains of serogroups O1 and O2a, which are the most frequently found serogroups in clinical outbreaks of vibriosis. All of the V. anguillarum strains were able to activate complement in rainbow trout serum, but smooth strains of V. anguillarum serogroup O1 were resistant to complement-mediated killing in the absence of specific antibodies. In the case of V. anguillarum serogroup O2a strains, 80% of the analyzed strains were resistant to rainbow trout serum even when specific antibodies were present. Analysis of the lipopolysaccharide structures of the tested V. anguillarum strains showed a positive correlation between the O-antigen size of the lipopolysaccharide and resistance to serum killing. The classical complement pathway was responsible for the antibody-dependent serum killing of susceptible V. anguillarum strains. When serum-resistant V. anguillarum serogroup O2a strains were grown in glucose-enriched Lennox L broth, they produced lipopolysaccharide molecules with fewer high-molecular-weight O-antigen units than did strains grown in broth without the addition of glucose. Strains grown in glucose-enriched medium became sensitive to rainbow trout serum killing, indicating that the high-molecular-weight O-antigen side chains prevented the activated complement from damaging the bacterium.

Download Full-text

Yersinia ruckeri Isolates Recovered from Diseased Atlantic Salmon (Salmo salar) in Scotland Are More Diverse than Those from Rainbow Trout (Oncorhynchus mykiss) and Represent Distinct Subpopulations

Applied and Environmental Microbiology ◽

10.1128/aem.01173-16 ◽

2016 ◽

Vol 82 (19) ◽

pp. 5785-5794 ◽

Cited By ~ 13

Author(s):

Michael J. Ormsby ◽

Thomas Caws ◽

Richard Burchmore ◽

Tim Wallis ◽

David W. Verner-Jeffreys ◽

...

Keyword(s):

Rainbow Trout ◽

Atlantic Salmon ◽

Oncorhynchus Mykiss ◽

Salmo Salar ◽

Significant Proportion ◽

Bacterial Pathogen ◽

Yersinia Ruckeri ◽

Content Type ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Relationship Of

ABSTRACTYersinia ruckeriis the etiological agent of enteric redmouth (ERM) disease of farmed salmonids. Enteric redmouth disease is traditionally associated with rainbow trout (Oncorhynchus mykiss, Walbaum), but its incidence in Atlantic salmon (Salmo salar) is increasing.Yersinia ruckeriisolates recovered from diseased Atlantic salmon have been poorly characterized, and very little is known about the relationship of the isolates associated with these two species. Phenotypic approaches were used to characterize 109Y. ruckeriisolates recovered over a 14-year period from infected Atlantic salmon in Scotland; 26 isolates from infected rainbow trout were also characterized. Biotyping, serotyping, and comparison of outer membrane protein profiles identified 19Y. ruckericlones associated with Atlantic salmon but only five associated with rainbow trout; none of the Atlantic salmon clones occurred in rainbow trout andvice versa. These findings suggest that distinct subpopulations ofY. ruckeriare associated with each species. A new O serotype (designated O8) was identified in 56 biotype 1 Atlantic salmon isolates and was the most common serotype identified from 2006 to 2011 and in 2014, suggesting an increased prevalence during the time period sampled. Rainbow trout isolates were represented almost exclusively by the same biotype 2, serotype O1 clone that has been responsible for the majority of ERM outbreaks in this species within the United Kingdom since the 1980s. However, the identification of two biotype 2, serotype O8 isolates in rainbow trout suggests that vaccines containing serotypes O1 and O8 should be evaluated in both rainbow trout and Atlantic salmon for application in Scotland.IMPORTANCEVaccination plays an important role in protecting Atlantic salmon against the bacterial pathogenYersinia ruckeri, but, in recent years, there has been an increasing incidence of vaccine breakdown in salmon. This is largely because current vaccines are aimed at rainbow trout and are based on serotypes specific for this species. A wider range of serotypes is responsible for infection in Atlantic salmon, but very little is known about the diversity of these strains and their relationships to those recovered from rainbow trout. In the present study, we demonstrate thatY. ruckeriisolates recovered from diseased Atlantic salmon in Scotland are more diverse than those from rainbow trout; furthermore, isolates from the two species represent distinct subpopulations. In addition, a new O serotype was identified that is responsible for a significant proportion of the disease in Atlantic salmon. Our findings are likely to have important implications for the development of improved vaccines againstY. ruckeri.

Download Full-text

Comparative susceptibility of Atlantic salmon, lake trout and rainbow trout to Myxobolus cerebralis in controlled laboratory exposures

Diseases of Aquatic Organisms ◽

10.3354/dao058027 ◽

2004 ◽

Vol 58 ◽

pp. 27-34 ◽

Cited By ~ 11

Author(s):

VS Blazer ◽

CL Densmore ◽

WB Schill ◽

DD Cartwright ◽

SJ Page

Keyword(s):

Rainbow Trout ◽

Atlantic Salmon ◽

Lake Trout ◽

Myxobolus Cerebralis ◽

Comparative Susceptibility

Download Full-text

Genome-scale comparative analysis for host resistance against sea lice between Atlantic salmon and rainbow trout

Scientific Reports ◽

10.1038/s41598-021-92425-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Pablo Cáceres ◽

Agustín Barría ◽

Kris A. Christensen ◽

Liane N. Bassini ◽

Katharina Correa ◽

...

Keyword(s):

Rainbow Trout ◽

Atlantic Salmon ◽

Candidate Genes ◽

Protein Phosphatase ◽

Sea Lice ◽

Genome Wide Association Studies ◽

Dual Specificity ◽

Dual Specificity Protein Phosphatase ◽

Genomic Regions ◽

Specificity Protein

AbstractSea lice (Caligus rogercresseyi) is an ectoparasite which causes major production losses in the salmon aquaculture industry worldwide. Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) are two of the most susceptible salmonid species to sea lice infestation. The objectives of this study were to: (1) identify genomic regions associated with resistance to Caligus rogercresseyi in Atlantic salmon and rainbow trout by performing single-step Genome-Wide Association studies (ssGWAS), and (2) identify candidate genes related to trait variation based on exploring orthologous genes within the associated regions across species. A total of 2626 Atlantic salmon and 2643 rainbow trout were challenged and genotyped with 50 K and 57 K SNP panels, respectively. We ran two independent ssGWAS for sea lice resistance on each species and identified 7 and 13 regions explaining more than 1% of the genetic variance for the trait, with the most important regions explaining 3% and 2.7% for Atlantic salmon and rainbow trout, respectively. We identified genes associated with immune response, cytoskeleton function, and cell migration when focusing on important genomic regions for each species. Moreover, we found 15 common orthogroups which were present in more than one associated genomic region, within- or between-species; however, only one orthogroup showed a clear potential biological relevance in the response against sea lice. For instance, dual-specificity protein phosphatase 10-like (dusp10) and dual-specificity protein phosphatase 8 (dusp8) were found in genomic regions associated with lice density in Atlantic salmon and rainbow trout, respectively. Dusp10 and dusp8 are modulators of the MAPK pathway and might be involved in the differences of the inflammation response between lice resistant and susceptible fish from both species. Our results provide further knowledge on candidate genes related to sea lice resistance and may help establish better control for sea lice in fish populations.

Download Full-text