Some viruses thwart bacterial defenses with a unique genetic alphabet
DNA has four building blocks: A, C, T and G. But some bacteriophages swap A for Z
Some bacteria-infecting viruses from the Siphoviridae (left) and Podoviridae (right) families illustrated here use a different DNA letter, Z, instead of the standard A.
Science Photo Library/Alamy Stock Photo
Some bacteria-killing viruses spell out their genetic instructions in a different DNA alphabet.