Data from: Mice infected with low-virulence strains of Toxoplasma gondii lose their innate aversion to cat urine, even after extensive parasite clearance

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.

已有研究证实，啮齿类中间宿主感染刚地弓形虫（Toxoplasma gondii）进入慢性期后，会丧失对其终宿主猫的先天固有恐惧。然而，该行为反应在刚地弓形虫不同毒株中的普遍性，以及病原体介导此类行为改变的潜在机制，目前仍未明确。为探究上述问题，本研究选取刚地弓形虫北美三大主要克隆谱系中的两株此前未被研究的分离株——III型毒株与I型减毒株，评估其感染对宿主的影响。本研究采用针对该实验优化的1小时旷场活动检测法，测定小鼠对捕食者与非捕食者尿液的厌恶程度。实验结果表明，丧失对猫尿液的先天厌恶感，是感染刚地弓形虫三大主要克隆谱系任意一株后均会出现的共性特征。令人意外的是，本研究发现，在感染I型减毒株后，即便在体内无法检测到弓形虫以及活动性脑部炎症的时间点，小鼠对猫尿的厌恶感仍会持续丧失。这一结果提示，刚地弓形虫介导的小鼠先天猫尿厌恶感丧失，可能在急性感染早期即发生且为永久性改变，无需依赖弓形虫包囊的持续存在或脑部炎症的持续发生。