Spleen and head kidney differential gene expression patterns in trout infected with Lactococcus garvieae correlate with spleen granulomas

Authors’ contributions AG and MMB designed the study. RC, AG and JC did most of the array experiments and performed the statistical analyses. AG, MMB, JFFG carried out the infection experiments and cared for the fsh. ARB performed the histopathological studies. LJ performed the statistical analyses. The manuscript was written by AG and RC, and critically reviewed by JC, MMB and JFFG who contributed to writing the manuscript. All authors read and approved the final manuscript.
Lactococcus garvieae is a significant pathogen in aquaculture with a potential zoonotic risk. To begin to characterize the late immune response of trout to lactococcosis, we selected infected individuals showing clinical signs of lactococcosis. At the time lactococcosis clinical signs appeared, infection by L. garvieae induced a robust inflammatory response in the spleen of rainbow trout, which correlated with abundant granulomatous lesions. The response in kidney goes in parallel with that of spleen, and most of the gene regulations are similar in both organs. A correlation existed between the early inflammatory granulomas in spleen (containing macrophages with internalized L. garvieae) and up-regulated gene sets, which defined the presence of macrophages and neutrophils. This is the first analysis of the immune transcriptome of rainbow trout following L. garvieae infection during the initiation of adaptive immune mechanisms and shows a ranscriptome induction of antibody response by both IgM (+) and IgT (+) spleen B cells to respond to systemic infection. These results increase our understanding of lactococcosis and pave the way for future research to improve control measures of lactococcosis on fish farms.
Ministerio Español de Economía y Competitividad (AGL 2012-35419 y AGL2014-51773-C3-3-R )
Comunidad de Madrid (S2013/ABI-2747 (TAVS-CAM))
Unión Europea
Depto. de Sanidad Animal
Fac. de Veterinaria
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