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Original Article |
inducible Genes with Essential, Pathogen-specific Roles in Resistance to Infection
Correspondence to: Gregory A. Taylor, Duke University Medical Center, P.O. Box 3003, Durham, NC 27710. Tel:919-286-0411 ext. 1-7744 Fax:919-286-6823 E-mail:gregory.taylor{at}duke.edu.
The cytokine interferon (IFN)-
regulates immune clearance of parasitic, bacterial, and viral infections; however, the underlying mechanisms are poorly understood. Recently, a family of IFN-
induced genes has been identified that encode 48-kD GTP-binding proteins that localize to the endoplasmic reticulum of cells. The prototype of this family, IGTP, has been shown to be required for host defense against acute infections with the protozoan parasite Toxoplasma gondii, but not for normal clearance of the bacterium Listeria monocytogenes and murine cytomegalovirus (MCMV). To determine whether other members of the gene family also play important roles in immune defense, we generated mice that lacked expression of the genes LRG-47 and IRG-47, and examined their responses to representative pathogens. After infection with T. gondii, LRG-47deficient mice succumbed uniformly and rapidly during the acute phase of the infection; in contrast, IRG-47deficient mice displayed only partially decreased resistance that was not manifested until the chronic phase. After infection with L. monocytogenes, LRG-47deficient mice exhibited a profound loss of resistance, whereas IRG-47deficient mice exhibited completely normal resistance. In addition, both strains displayed normal clearance of MCMV. Thus, LRG-47 and IRG-47 have vital, but distinct roles in immune defense against protozoan and bacterial infections.
Key Words: interferon, GTPase, protozoa, bacteria, virus
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