TREX1 digests unpaired nucleotides on ssDNA and dsDNA ends through a 3' to 5' exonuclease activity (Perrino FW et al. 1994; de Silva U et al. 2007; Lehtinen DA et al. 2008; Fye JM et al 2011). Upon viral infection the TREX1-deficient human and mouse cells were found to be more resistant to different types of RNA viruses, suggesting that TREX1 activity may inhibit the host innate immune responses by clearing viral DNA generated during reverse transcription (Yan N et al. 2010; Hasan M et al. 2012).