Toxic component of a type II toxin-antitoxin (TA) system. A probable translation-dependent mRNA interferase. Probably counteracted by antitoxin HigA. Probably forms a complex with the antitoxin HigA which inhibits the mRNA interferase activity. Deletion of the higB-higA operon has no effect on virulence in mouse infection; the disrupted strain is as virulent as wild-type. Belongs to the HigB mRNA interferase family.