BTLA was reported to be a crucial molecular marker in “immunoparalysis” associated with sepsis (24), and it was shown to play a positive regulatory role in viral diseases; for example, mouse hepatitis virus-3 (MHV3) could induce BTLA signaling and cause acute liver failure through phagocyte activation and secretion of the inflammatory molecules TNF-α and FGL2 (25). Here, BTLA is linked to viral infectious disease.