Adult Mytilus galloprovincialis mussels were injected into the posterior adductor muscle with 100 ul of polyinosinic:polycytidylic acid (poly I:C Sigma-Aldrich) at a final concentration of 1mg/ml. Control mussels were injected with the same volume of L15 medium. A volume of 1 ml of hemolymph from each animal was sampled. RNA isolation was carried out (3 controls and 3 poly I:C-treated mussels) using the Maxwell 16 LEV simply RNA kit (Promega). TruSeq Stranded mRNA LT Sample Preparation Kit from Illumina was used for RNA sequencing. The paired-end 150 bp reads were obtained by Illumina NovaSeq 6000 sequencer.