On the other hand, HCV-associated cNK cells showed a pro-inflammatory profile, with high expression of the chemoattractants CCL3, CCL4, and XCL1, and the ligand TNFSF9 (CD137L), a costimulatory signal that can induce CD8+ T cells response against viral infection (57). This evidence concerns the gene TNFSF9 and viral infectious disease.