Humans can become infected with the protozoan Toxoplasma gondii by ingesting it during its spore-like stages, which are shed in cat faeces. The three main strains of T. gondii vary widely in terms of virulence in mice, and researchers have pinpointed a gene that may underlie this difference.
David Sibley at Washington University in St Louis, Missouri, and his co-workers generated a genetic cross between the type I strain, which is lethal to lab mice, and the milder type II. The progeny were injected into mice to assess their virulence. A genome-wide association analysis of the progeny and the parental strains revealed a locus on chromosome XII that accounted for 90% of the heightened virulence. Deleting a gene within this region, ROP5, in the type I strain completely blocked acute virulence.
The authors suggest that the ROP5 protein may regulate other proteins that control virulence in the parasite.
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Protein behind protozoan power. Nature 474, 9 (2011). https://doi.org/10.1038/474009d
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DOI: https://doi.org/10.1038/474009d