Immunity protein component of a toxin-immunity protein module, which functions as a cellular contact-dependent growth inhibition (CDI) system. Neutralizes the tRNase activity of cognate toxin WapA upon expression in E.coli. Does not inhibit WapA from other strains of B.subtilis. The WapA C-terminus cannot be expressed on its own in E.coli, however it can be cloned in the presence of its cognate immunity protein gene. Cell contact is probably necessary for growth inhibition.