NKX2-5 and infection: The ribonuclease activity of Csx1/Csm6 is crucial for the clearance of MGEs (Hatoum-Aslan et al., 2014; Foster et al., 2019; Grüschow et al., 2019), particularly when viral genes are transcribed late in infection, at low levels or mutated (Hatoum-Aslan et al., 2014; Jiang et al., 2016; Rostøl and Marraffini, 2019).