XBP-1, a Cellular Target for the Development of Novel Anti-viral Strategies

X-box binding protein 1 (XBP-1) is a key regulator of the unfolded protein response (UPR), which is activated in response to endoplasmic reticulum (ER) stress. Cells contain two protein isoforms of XBP-1, the active isoform (XBP-1S) and the inactive isoform (XBP-1U). Induction of UPR leads to the generation of XBP-1S while XBP-1U is dominant in ER stress-free cells. XBP-1S is a transcriptional activator and regulates the expression of a subset of UPR genes. Importantly, recent studies have demonstrated the essential role of XBP-1S in various human diseases, such as viral infections. Many viruses have evolved to manipulate UPR/XBP-1 of the infected cells to promote viral survival and replication. In this review, we will summarize the current findings on the involvement of XBP-1 in viral infection/ replication and discuss the potential anti-viral strategies by targeting XBP-1.