B2 elements have contributed non-coding RNAs inducible by stress or infection (Allen et al., 2004; Karijolich et al., 2017; Karijolich et al., 2015; Li et al., 1999; Schaller et al., 2020; Walters et al., 2009; Wick et al., 2003; Williams et al., 2004), splicing signals (Kress et al., 1984), promoter elements (Ferrigno et al., 2001), and CTCF-bound insulator elements (Ichiyanagi et al., 2021; Lunyak et al., 2007; Schmidt et al., 2012). Here, CTCF is linked to infection.