Bacteriophage anti-CRISPR proteins inactivate Listeria monocytogenes CRISPR-Cas9 Half of L. monocytogenes isolates possess inhibited CRISPR-Cas9 systems AcrIIA2 and AcrIIA4 prevent target binding by dCas9 in bacteria AcrIIA2 and AcrIIA4 inhibit Cas9-mediated gene editing in human cells