Torelli Francesca, Butterworth Simon, Lockyer Eloise, Matias Ana N, Hildebrandt Franziska, Song Ok-Ryul, Pearson-Farr Jennifer, Treeck Moritz
Signalling in Apicomplexan Parasites Laboratory, The Francis Crick Institute, London, UK.
The Cell Biology of Host-Pathogen Interactions Lab, Gulbenkian Institute for Molecular Medicine, Lisbon, Portugal.
Nat Commun. 2025 Apr 16;16(1):3570. doi: 10.1038/s41467-025-58876-2.
Toxoplasma gondii parasites exhibit extraordinary host promiscuity owing to over 250 putative secreted proteins that disrupt host cell functions, enabling parasite persistence. However, most of the known effector proteins are specific to Toxoplasma genotypes or hosts. To identify virulence factors that function across different parasite isolates and mouse strains that differ in susceptibility to infection, we performed systematic pooled in vivo CRISPR-Cas9 screens targeting the Toxoplasma secretome. We identified several proteins required for infection across parasite strains and mouse species, of which the dense granule protein 12 (GRA12) emerged as the most important effector protein during acute infection. GRA12 deletion in IFNγ-activated macrophages results in collapsed parasitophorous vacuoles and increased host cell necrosis, which is partially rescued by inhibiting early parasite egress. GRA12 orthologues from related coccidian parasites, including Neospora caninum and Hammondia hammondi, complement TgΔGRA12 in vitro, suggesting a common mechanism of protection from immune clearance by their hosts.
由于超过250种假定的分泌蛋白会破坏宿主细胞功能，从而使寄生虫得以持续存在，弓形虫寄生虫表现出异常广泛的宿主适应性。然而，大多数已知的效应蛋白是弓形虫特定基因型或宿主所特有的。为了鉴定在不同寄生虫分离株和对感染易感性不同的小鼠品系中起作用的毒力因子，我们针对弓形虫分泌组进行了系统性的体内CRISPR-Cas9筛选。我们鉴定出了几种在不同寄生虫菌株和小鼠物种感染过程中所需的蛋白质，其中致密颗粒蛋白12（GRA12）在急性感染期间成为最重要的效应蛋白。IFNγ激活的巨噬细胞中GRA12缺失会导致寄生泡塌陷和宿主细胞坏死增加，通过抑制早期寄生虫逸出可部分挽救这种情况。来自相关球虫寄生虫（包括犬新孢子虫和哈氏 Hammondia hammondi）的GRA12直系同源物在体外可补充TgΔGRA12，这表明它们具有防止被宿主免疫清除的共同机制。
