Toxoplasma gondii is a widespread parasite of warm-blooded vertebrates that also causes opportunistic infections in humans. Rodents are a natural host for asexually replicating forms, whereas cats serve as the definitive host for sexual development. The laboratory mouse provides a model to study pathogenesis. Strains of T. gondii are globally diverse, with more than 16 distinct haplogroups clustered into 6 major clades. Forward genetic analysis of genetic crosses between different lineages has been used to define the molecular basis of acute virulence in the mouse. These studies have identified a family of secretory serine/threonine rhoptry kinases that target innate immune pathways to protect intracellular parasites from destruction. Rhoptry kinases target immunity-related GTPases, a family of immune effectors that is expanded in rodents. Similar forward genetic studies may be useful to define the basis of pathogenesis in other hosts, including humans, where infections of different strains present with variable clinical severity.

中文翻译：

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弓形虫致病因素的遗传图谱

弓形虫是温血脊椎动物的一种广泛寄生虫，它还会在人类中引起机会性感染。啮齿动物是无性复制形式的天然宿主，而猫则是性发育的最终宿主。实验小鼠提供了研究发病机理的模型。弓形虫菌株在全球范围内是不同的，有超过16个不同的单倍群聚集到6个主要进化枝中。对不同谱系之间遗传杂交的正向遗传分析已用于定义小鼠急性毒力的分子基础。这些研究已经确定了靶向先天免疫途径以保护细胞内寄生虫免遭破坏的分泌型丝氨酸/苏氨酸Rhoptry激酶家族。Rhoptry激酶靶向与免疫有关的GTPases，后者是在啮齿动物中扩展的一种免疫效应子。类似的前瞻性遗传研究可能有助于确定其他宿主（包括人）中发病机理的基础，在这些宿主中，不同菌株的感染存在不同的临床严重程度。