self vs foreign

Foreigner or native-born? Your immune system discriminates between them, as do those of bacteria. Yes indeed, bacteria do have immune systems – pretty complex ones at that. And like any useful immune system, the bacterial ones must have a good technique for distinguishing “foreign” from “self.” You may even have heard of the bacterial immune system: It’s called CRISPR, and it’s used in biology research around the world for DNA engineering and genome editing. CRISPR normally inserts short DNA sequences taken from phages – viruses that invade bacteria – into special slots called spacers within…