“…CRISPR‐Cas systems function as an adaptive immune system, able to acquire short segments of viral DNA from previous infections and archiving them into arrays with defined spacer sequences that guide the associated interference machinery to target and destroy complementary sequences upon subsequent infections (Hille et al, 2018; Watson et al, 2021), while abortive infection systems like AbiA, AbiK, Lit, and anti‐codon nucleases like PrrC and RloC behave as suicide switches that induce cell death as an antiviral defense (Blanga‐Kanfi et al, 2006; Davidov & Kaufmann, 2008; Kao & Snyder, 1988; Tangney & Fitzgerald, 2002; Wang et al, 2011). Some systems employ chemical modulators to disrupt phage replication directly (Kronheim et al, 2018) while others like Type III CRISPR complexes, Thoeris, CBASS (cyclic nucleotide‐based anti‐phage signaling system), and PYCSAR (pyrimidine cyclase system for anti‐phage resistance) use cyclic nucleotides as second messengers to activate a diverse range of effector proteins that in turn provide the critical defense activities (Athukoralage & White, 2022; Cohen et al, 2019; Duncan‐Lowey & Kranzusch, 2022; Govande et al, 2021; Kazlauskiene et al, 2017; Lau et al, 2020; Manik et al, 2022; Millman, Melamed, et al, 2020; Niewoehner et al, 2017; Ofir et al, 2021; Rouillon et al, 2018; Rouillon et al, 2023; Tal et al, 2021). The Wadjet system recognizes DNA topology in closed circular DNA to protect hosts against plasmid transformation (Deep et al, 2022).…”