Cell-mediated immune response against mycolic acids of Mycobacteroides salmoniphilum in rainbow trout Oncorhynchus mykiss

Mycobacteriosis caused by Mycobacterium spp. causes economic damages to the world aquaculture industry. In mammals, mycolic acids contained in the cell wall of Mycobacterium spp. are presented by CD1b molecule as lipid antigens and induce cell-mediated immunity (CMI). Here, we investigated CMI responses against the mycolic acids of Mycobacterioides salmoniphilum in a CD1-lacking teleost fish, rainbow trout. After stimulation of trout leukocytes with mycolic acids, the number and percentage of CD8 alpha+ T cells increased. Fish immunized with mycolic acids showed an up-regulation of IFN-gamma. Further, in vitro re-stimulation of leukocytes derived from immunized fish resulted in proliferation of CD8 alpha+ cells. These data suggest that mycolic acids are recognized as lipid antigens resulting in an activation of rainbow trout CD8 alpha+ cells and up-regulation of the Th1 cytokine IFN-gamma. The mycolic acids are promising candidates for vaccines to activate CD8 alpha+ T cells against fish mycobacteriosis.

Automated summary

The study shows that rainbow trout lacking CD1 can elicit cell-mediated immune responses against Mycobacterioides salmoniphilum mycolic acids, indicating their potential as vaccine candidates to activate CD8α+ T cells.