Toxic component of a type II toxin-antitoxin (TA) system. Has ssRNase activity. Upon expression in E.coli inhibits growth in liquid culture; this toxic effect is neutralized by coexpression with cognate antitoxin VapB1. Its RNase activity is partially inhibited in vitro by VapB1 (PubMed:22046301). Belongs to the PINc/VapC protein family.