Aquaculture Canada and WAS North America 2022

August 15 - 18, 2022

St Johns, Newfoundland, Canada

COMPARATIVE SUSCEPTIBILITY AND IMMUNE RESPONSEOF ATLANTIC SALMON Salmo salar L. FARMED, WILD AND HYBRID CROSSES TO Aeromonas salmonicida subsp. salmonicida INFECTION

Dang. M*, S. Dove2, T. Cao1, A. Hossain1, H. Gnanagobal1, I. Vasquez1, M. Soto – Dávila1, S. Chakraborty1, M. Rise2, I. Fleming2, J. Westcott3, J. Santander1

 

*&1Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL, Canada; 2Department of Ocean Sciences, Memorial University of Newfoundland, St John´s, NL, Canada; 3Fisheries and Marine Institute of Memorial University of Newfoundland, St. John’s, NL, Canada;

tmtdang@mun.ca

 



 Aeromonas salmonicida  subsp. salmonicida

is the causative agent of furunculosis in several fish species including Atlantic salmon (Salmo salar). Although g enetic susceptibility and resistance to A. salmonicida have been documented in salmon, the mechanisms are not well understood. Here, we compared naïve and immunized Atlantic salmon from farmed, wild and hybrid crosses to A. salmonicida susceptibility and immune response.  Naïve fish were intraperitoneally

injected with 2.5×104 CFU/100g and the immunized fish were challenged with 4×106 CFU/100g at 10 weeks post-primary immunization. Samples of tissues were taken at different time points .  We found that naïve wild salmon were significantly more susceptible to A. salmonicida infection than the farmed and hybrid crosses (p <0.001). Colonization of lymphoid tissues by A. salmonicida correlated with fish susceptibility. Expression of il-1β , il-10 , and tlr5

were up-regulated after 10 days post-infection with higher expression in farmed fish in contrast to wild fish.  Expression of tnfα , igM were up-regulated in farmed fish, but down-regulated in wild fish. In contrast to naïve fish, no differences in susceptibility were found between vaccinated fish challenged with A. salmonicida .  This study provides new insights into Atlantic salmon immune response and susceptibility to A.

salmonicida infection and immunization.