SP110 and tuberculosis: One particular variant of Ifi75 encoding a full length protein corresponding to the Sp110b isoform, which we named Ipr1 (for intracellular pathogen resistance), was found to be absent in the lungs of M. tuberculosis infected sst1 susceptible mice compared to sst1 resistant mice, and expression of Ipr1 in macrophages both in vitro and in vivo restored many key functions of tuberculosis resistance on the sst1 susceptible background [6].