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Aus der Forschung => Neues aus der Forschung => Topic started by: Julian on January 14, 2014, 01:59:03 PM

Title: Fear no fear! Parasite Toxoplasma gondii strikes again.
Post by: Julian on January 14, 2014, 01:59:03 PM
http://blogs.plos.org/everyone/2014/01/14/headline-please-2013-plos-one-papers-media/

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10. What, the Cat? Oh, He’s Harmless

http://blogs.plos.org/everyone/files/2014/01/1091487059_7d9e530e28_o.jpg

Image credit: Denis Defreyne

Our favorite parasite Toxoplasma gondii strikes again. Mice are normally terrified of cats, and rightly so, but Berkeley researchers (including a PLOS founder Mike Eisen) in “Mice Infected with Low-Virulence Strains of Toxoplasma gondii Lose Their Innate Aversion to Cat Urine, Even after Extensive Parasite Clearance” show that mouse exposure to the parasite, carried in cat feces, may alter the mouse’s brain, causing the mouse to permanently lose its fear of cats. The story received coverage from several news outlets, including a CNN segment by Charlie Rose, and coverage by BBC, National Geographic Phenomena, and Nature.
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http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0075246

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Mice Infected with Low-Virulence Strains of Toxoplasma gondii Lose Their Innate Aversion to Cat Urine, Even after Extensive Parasite Clearance

    Wendy Marie Ingram,
    Leeanne M. Goodrich,
    Ellen A. Robey mail,
    Michael B. Eisen mail

    Published: September 18, 2013
    DOI: 10.1371/journal.pone.0075246

Abstract

Toxoplasma gondii chronic infection in rodent secondary hosts has been reported to lead to a loss of innate, hard-wired fear toward cats, its primary host. However the generality of this response across T. gondii strains and the underlying mechanism for this pathogen-mediated behavioral change remain unknown. To begin exploring these questions, we evaluated the effects of infection with two previously uninvestigated isolates from the three major North American clonal lineages of T. gondii, Type III and an attenuated strain of Type I. Using an hour-long open field activity assay optimized for this purpose, we measured mouse aversion toward predator and non-predator urines. We show that loss of innate aversion of cat urine is a general trait caused by infection with any of the three major clonal lineages of parasite. Surprisingly, we found that infection with the attenuated Type I parasite results in sustained loss of aversion at times post infection when neither parasite nor ongoing brain inflammation were detectable. This suggests that T. gondii-mediated interruption of mouse innate aversion toward cat urine may occur during early acute infection in a permanent manner, not requiring persistence of parasite cysts or continuing brain inflammation.
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