ADARs and the balance game between virus infection and innate immune cell response

All viruses that have dsRNA structures at any stages of their life cycle may potentially undergo RNA editing events mediated by ADAR enzymes. Indeed, an increasing number of studies that describe A-to-I sequence changes in viral genomes and/or transcripts, consistent with ADAR deaminase activity, has been reported so far. These modifications can appear as either hyperediting or specific RNA editing events in viral dsRNAs. It is now well established that ADAR enzymes can affect viral life cycles in an editing-dependent and -independent manner, with ADARs acting as pro- or antiviral factors. Despite the discovery of editing events in viral RNAs dates back to thirty years ago, the biological consequences of A-to-I changes during viral infection is still far to be completely elucidated. In this review, past and recent studies on the importance of ADAR enzymes on several viruses will be examined.