ERN1 and infection: De Jong et al. [14] suggested that B. abortus infection activated the IRE1 pathway, whereas Smith et al. [15] showed that all three UPR pathways were induced in infection of murine macrophages with B. melitensis. However, the precise role of the UPR in the intracellular life of Brucella spp., the host factors involved in replication processes, and the mechanism by which Brucella modulates the UPR remain unknown.