Imprecise Spacer Acquisition Generates CRISPR-Cas Immune Diversity through Primed Adaptation (Cell Host & Microbe)

CRISPR-Cas prokaryotic immune systems acquire genetic memories, termed spacers, to facilitate defense against phages and mobile genetic elements. Jackson et al. (2018) discover that imprecisely acquired (slipped) spacers are less effective for defense but enhance the acquisition of new spacers, which pre-emptively increases immune diversity before phage escape mutants arise.