Host Susceptibility toBrucella abortusInfection Is More Pronounced in IFN-γknockout than IL-12/β2-Microglobulin Double-Deficient Mice

摘要

Brucella abortusis a facultative intracellular bacterial pathogen that causes abortion in domestic animals and undulant fever in humans. IFN-γ, IL-12, and CD8+ T lymphocytes are important components of host immune responses againstB. abortus. Herein, IFN-γand IL-12/β2-microglobulin (β2-m) knockout mice were used to determine whether CD8+ T cells and IL-12-dependent IFN-γdeficiency would be more critical to controlB. abortusinfection compared to the lack of endogenous IFN-γ. At 1 week after infection, IFN-γKO and IL-12/β2-m KO mice showed increased numbers of bacterial load in spleens; however, at 3 weeks postinfection (p.i.), only IFN-γKO succumbed toBrucella. All IFN-γKO had died at 16 days p.i. whereas death within the IL-12/β2-m KO group was delayed and occurred at 32 days until 47 days postinfection. Susceptibility of IL-12/β2-m KO animals toBrucellawas associated to undetectable levels of IFN-γin mouse splenocytes and inability of these cells to lyseBrucella-infected macrophages. However, the lack of endogenous IFN-γwas found to be more important to control brucellosis than CD8+ T cells and IL-12-dependent IFN-γdeficiencies.