Study design (A) and administration routes (B).
A Treatment groups (n = 90) were challenged as described in the “Materials and methods” section. To assess potential leakage of challenge inoculate, naïve fish were introduced to challenged groups after two rounds of water exchange, and then after 24 h transferred to a separate tank. Timeline specifies sampling schedule days post challenge (dpc) and weeks post challenge (wpc). #Leakage control cohabitants were only sampled at 56 dpc. B Arrows indicate where challenge material was deposited and circles indicate where gastrointestinal samples were taken (stomach (S), pyloric caeca (PC), mid-intestine (MI) and the distal intestine (DI)). B modified with courtesy of Inge Bjerkås, Oslo, Norway.