Antitoxin component of a type II toxin-antitoxin (TA) system. Cognate toxin is VapC27. Upon expression in E.coli partially counteracts the ribonuclease activity of non-cognate toxins MazF6 and MazF9. Interacts with cognate toxin VapC27 and non-cognate toxins MazF6 and VapC40. Interaction with MazF6 and MazF9 partially neutralizes the toxins. Belongs to the VapB family.