Type I IFNs play critical roles in orchestrating the
antiviral defense by inducing direct
antiviral activities and shaping the adaptive immune response. Viruses have evolved numerous strategies to specifically interfere with IFN production or its downstream mediators, thereby allowing successful
infection of the host to occur. The prototypic human gammaherpesvirus EBV, which is associated with
infectious mononucleosis and malignant
tumors, harbors many immune-evasion
proteins that manipulate the adaptive and innate immune systems. In addition to
proteins, the virus encodes >40 mature
microRNAs for which the functions remain largely unknown. In this article, we identify EBV-encoded miR-BART16 as a novel viral immune-evasion factor that interferes with the type I IFN signaling pathway. miR-BART16 directly targets
CREB-binding protein, a key transcriptional coactivator in IFN signaling, thereby inducing
CREB-binding protein downregulation in EBV-transformed B cells and gastric
carcinoma cells. miR-BART16 abrogates the production of IFN-stimulated genes in response to IFN-α stimulation and it inhibits the antiproliferative effect of IFN-α on latently infected BL cells. By obstructing the type I IFN-induced
antiviral response, miR-BART16 provides a means to facilitate the establishment of latent
EBV infection and enhance viral replication.