Multi-Organ Transcriptome Response of Lumpfish () to Subspecies Systemic Infection.

Lumpfish is utilized as a cleaner fish to biocontrol sealice infestations in Atlantic salmon farms. , a Gram-negative facultative intracellular pathogen, is the causative agent of furunculosis in several fish species, including lumpfish. In this study, lumpfish were intraperitoneally injected with different doses of to calculate the LD. Samples of blood, head-kidney, spleen, and liver were collected at different time points to determine the infection kinetics. We determined that LD is 10 CFU per dose. We found that the lumpfish head-kidney is the primary target organ of . Triplicate biological samples were collected from head-kidney, spleen, and liver pre-infection and at 3- and 10-days post-infection for RNA-sequencing. The reference genome-guided transcriptome assembly resulted in 6246 differentially expressed genes. The assembly resulted in 403,204 transcripts, which added 1307 novel genes not identified by the reference genome-guided transcriptome. Differential gene expression and gene ontology enrichment analyses suggested that induces lethal infection in lumpfish by uncontrolled and detrimental blood coagulation, complement activation, inflammation, DNA damage, suppression of the adaptive immune system, and prevention of cytoskeleton formation.