Adaptive antiviral defense mechanisms, in archaea and bacteria, based on DNA repeat arrays called CLUSTERED REGULARLY INTERSPACED SHORT PALINDROMIC REPEATS (CRISPR elements) that function in conjunction with CRISPR-ASSOCIATED PROTEINS (Cas proteins). Several types have been distinguished, including Type I, Type II, and Type III, based on signature motifs of CRISPR-ASSOCIATED PROTEINS.

Synonyms: Systems, CRISPR-Cas CRISPR-Cas System CRISPR-Cas Systems System, CRISPR-Cas CRISPR Cas Systems