The LxIS motif is the language between virus and host RLRs: From fish to mammalian viruses

Regulation of host interferon (IFN) production is a crucial strategy for viral immune escape. We propose that the LxIS motif language, a marker for exogenous viral proteins, interacts with host retinoic acid-inducible gene I (RIG-I)-like receptor (RLR) factors. In this study, the viral proteins containing the LxIS motif of grass carp reovirus (GCRV), and cyprinid herpesvirus 3 (CyHV-3), which belong to the fish RNA and DNA viruses, were found to interact with RLRs, and the general functions of these proteins were negative regulation of IFN activation. Terrestrial animal viruses with this motif language, such as SARS-CoV-2 and so on, are also examined. Several viral proteins that were not reported previously were found to be associated with the RLR pathway. Taken together, the LxIS motif language elucidates a straightforward and efficient method for identifying viral proteins that target host RLRs to regulate IFN expression, and is conserved in both lower and higher vertebrates.