Interferon gamma induced GTPase (IGTP) (also named Irgm3) and interferon gamma inducible protein 47 (IRG-47) (also named Irgd) are interferon (IFN)-inducible p47 GTPases that have been shown to regulate host resistance to intracellular pathogens. Little knowledge has been known about the role of p47 GTPases in host responses against extracellular pathogens. To investigate possible roles of IGTP and IRG-47 in the course of Schistosoma japonicum infection, IGTP and IRG-47 knockout and wild-type (WT) mice were challenged with cercariae of S. japonicum, and host responses were analyzed. At the acute stage of S. japonicum infection, mice that lacked IGTP displayed similar parasite burden and pathological damage to WT mice. Importantly, S. japonicurn-infected IRG-47-deficient mice, in contrast to IGTP-deficient mice and WT mice, showed significantly reduced worms and lower egg-burden,but intense granulomatous reaction evoked by schistosome eggs in peripheral parts of liver lobes. In addition, upregulation of inflammation-related gene expression was observed in the spleen of IRG-47-deficient mice using oligonucleotide microarrays, in which multiple pathways of cytokine-cytokine receptor interaction, T-cell receptor signaling, complement, coagulation cascades and cell adhesion molecules were highlighted. Taken together, these data suggest that IGTP and IRG-47 might have distinct features that were differentially required for resistance to S. japonicum.
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