Antitoxin component of a type II toxin-antitoxin (TA) system. Upon expression in E.coli neutralizes the effect of cognate toxin VapC. The VapB/VapC complex probably regulates transcription of its own promoter. Homodimer (Probable). Forms a hetero-octamer (4 VapB and 4 VapC) complex with toxin VapC. The complex binds 2 different sites in the vapBC promoter, probably via VapB dimerization. Degradation of tRNA(fMet) is induced by chloramphenicol treatment, suggesting the antitoxin is unstable when the growth rate decreases. Belongs to the VapB family.