Association between Yersinia ruckeri infection, cytokine expression and survival in rainbow trout (Oncorhynchus mykiss)

TY - JOUR

T1 - Association between Yersinia ruckeri infection, cytokine expression and survival in rainbow trout (Oncorhynchus mykiss)

AU - Raida, Martin Kristian

AU - Holten-Andersen, Lars

AU - Buchmann, Kurt

PY - 2011/6

Y1 - 2011/6

N2 - The immune response against bacterial pathogens has been widely studied in teleosts and it is evident that survival chances differ significantly within a host population. Identification of indicators for susceptibility and responsiveness will improve our understanding of this host-pathogen interaction. The present work shows that the transcripts of cytokine genes in blood cells sampled three days post-infection was significantly higher in fish which obtained a high bacteriemia and died at later time points when compared to both non-infected control fish and infected fish that survived the infection. Rainbow trout were infected by bath challenge in a bacterial suspension (LD60 dose, 1.8 × 109 CFU/ml Yersinia ruckeri for 1 h) and subsequently transferred to individual aquaria for 30 days of observation. Blood samples were analyzed for presence of Y. ruckeri both by culture and quantitative RT real-time PCR (qRT-PCR) and transcript levels of 28 genes encoding molecules which are important in the immune response. The transcript levels of a number of central cytokines, chemokines and cytokine receptors (IL-1β, IL-6, IL-8, IL-10, TNF-α, IL-receptor II) were significantly increased in infected fish that died later. In addition, a significantly higher amount of Y. ruckeri was found in the blood of the fish that died when compared to survivors. The study indicates that highly susceptible trout obtain an early heavy septicemia infection, which elicits a high up-regulation of the transcript of pro-inflammatory cytokines. Thus, less susceptible fish are protected by other factors and contract merely a weak non-lethal infection eliciting no or a weak cytokine response.

AB - The immune response against bacterial pathogens has been widely studied in teleosts and it is evident that survival chances differ significantly within a host population. Identification of indicators for susceptibility and responsiveness will improve our understanding of this host-pathogen interaction. The present work shows that the transcripts of cytokine genes in blood cells sampled three days post-infection was significantly higher in fish which obtained a high bacteriemia and died at later time points when compared to both non-infected control fish and infected fish that survived the infection. Rainbow trout were infected by bath challenge in a bacterial suspension (LD60 dose, 1.8 × 109 CFU/ml Yersinia ruckeri for 1 h) and subsequently transferred to individual aquaria for 30 days of observation. Blood samples were analyzed for presence of Y. ruckeri both by culture and quantitative RT real-time PCR (qRT-PCR) and transcript levels of 28 genes encoding molecules which are important in the immune response. The transcript levels of a number of central cytokines, chemokines and cytokine receptors (IL-1β, IL-6, IL-8, IL-10, TNF-α, IL-receptor II) were significantly increased in infected fish that died later. In addition, a significantly higher amount of Y. ruckeri was found in the blood of the fish that died when compared to survivors. The study indicates that highly susceptible trout obtain an early heavy septicemia infection, which elicits a high up-regulation of the transcript of pro-inflammatory cytokines. Thus, less susceptible fish are protected by other factors and contract merely a weak non-lethal infection eliciting no or a weak cytokine response.

KW - Laboratory animal

KW - Yersinia ruckeri

KW - Rainbow trout

KW - Pro-inflammatory cytokines

KW - Blood

KW - Susceptibility to infection

U2 - 10.1016/j.fsi.2011.03.022

DO - 10.1016/j.fsi.2011.03.022

M3 - Journal article

C2 - 21501689

SN - 1050-4648

VL - 30

SP - 1257

EP - 1264

JO - Fish and Shellfish Immunology

JF - Fish and Shellfish Immunology

IS - 6

ER -