Bacteriophages are the most common entities on earth and represent a constant challenge
to bacterial populations. To fend off bacteriophage infection, bacteria evolved immune
systems to avert phage adsorption and block invader DNA entry. They developed restriction–
modification systems and mechanisms to abort infection and interfere with virion assembly,
as well as newly recognized clustered regularly interspaced short palindromic repeats
(CRISPR). In response to bacterial immune systems, bacteriophages synchronously evolved …