BDNF and infection: Interestingly, the same miRNA can select different targets in different stages of pathogenesis, and downregulated miR-15a, for instance, fails to repress TGF-B/SMAD7 signaling in early infection [96,97,98], whereas our results indicate that downregulated miR-15a-5p can also repress GLI2/IGF1/PD1/eIF4E/BDNF/E2F3 in HBV-HCC serum [103,104,105,106,107].