DNA Has Four Bases. Some Viruses Swap in a Fifth Wired Magazine
"Z" was first discovered in 1977 in a phage
Now 200 phages (a virus that attacks bacteria) are known to have Z in their DNA
Evolution at work
“Z and other modified DNA bases seem to have evolved to help viruses evade the defenses with which bacteria degrade foreign genetic material.”
Apparently, normal DNA tests assume “A” and do not notice “Z” (2 Hydrogen bonds instead of one)
Wonder if they have gotten around to noticing if RNA virus (like Coronavirus) also use “Z”?