Skin immune response of rainbow trout (Oncorhynchus mykiss) experimentally exposed to the disease Red Mark Syndrome.

•Red Mark Syndrome (RMS) was transferred to naïve specific pathogen free fish.•Lesions in the skin showed a Th1-type profile using gene expression.•The same lesions showed a high expression of IgD, IgM and IgT.•Results support that MLO causes RMS.•Fish overcome the infection with a Th1-type response supplemented by antibodies.