What is "vapbc"

VapBC (virulence associated proteins B and C) is the largest family of type II toxin-antitoxin system genetic loci in prokaryotes. VapBC operons consist of two genes: VapC encodes a toxic PilT N-terminus (PIN) domain, and VapB encodes a matching antitoxin. The toxins in this family are thought to perform RNA cleavage, which is inhibited by the co-expression of the antitoxin, in a manner analogous to a poison and antidote.

First discovered in 1992, vapBC loci are now thought make up around 37–42% of all type II toxin-antitoxin systems.