Definitive identification of a gene that confers resistance against Toxoplasma cyst burden and encephalitis

C. R. Brown, C. A. Hunter, R. G. Estes, E. Beckmann, J. Forman, C. David, J. S. Remington, R. McLeod

Research output: Contribution to journalArticlepeer-review

136 Scopus citations


Control of resistance to cyst burden following per-oral infection with Toxoplasma gondii has been mapped previously to a region of mouse chromosome 17 of approximately 140 kb. This region is contiguous with and contains the class I gene, L(d). Resistance to development of toxoplasmic encephalitis has also been reported to be controlled by genes in this region of H-2. TNF-α, D and L genes, as well as unidentified genes, are also in this region. The work described here was performed to identify definitively the gene(s) in this 140 kb region that confers resistance to cysts and encephalitis. The study demonstrates that relative resistance to T. gondii organisms and cyst burden in brain, and toxoplasmic encephalitis, 30 days following per-oral T. gondii infection is correlated absolutely with the presence of the L(d) gene in inbred, recombinant, mutant and C3H.L(d) transgenic mice. Mice with the L(d) gene had lower cyst burdens and less encephalitis than those without the L(d) gene. Specifically, 30 days after infection mice with the L(d) gene had minimal perivascular inflammation and meningeal inflammation and very few Toxoplasma cysts or organisms in immunoperoxidase-stained preparations of their brains. Mice without the L(d) gene had a similar pattern of inflammation, but in addition they had collections of inflammatory cells in the brain parenchyma. Free tachyzoites were found within these foci of inflammation and cysts were present in these areas as well as in contiguous areas without inflammatory cells. There were CD4+ and CD8+ T lymphocytes in the areas of inflammation and throughout the brain parenchyma. Mice that were resistant to cysts and encephalitis had little detectable brain cytokine mRNA expression, while mice that were susceptible had elevated levels of mRNA for a wide range of cytokines, consistent with their greater amounts of inflammation. The present work definitively demonstrates that a L(d) restricted response decreases the number of organisms and cysts within the brain and thereby limits toxoplasmic encephalitis and levels of interferon-γ (IFN-γ), tumour necrosis factor-α (TNF-α), interleukin-2 (IL-2), IL-6, IL-10, transforming growth factor-β (TGF-β), IL-1α, IL-1β and macrophage inhibiting protein (MIP) mRNA in the brain 30 days after per-oral infection.

Original languageEnglish (US)
Pages (from-to)419-428
Number of pages10
Issue number3
StatePublished - 1995

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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