PT  - JOURNAL ARTICLE
AU  - Torelli, Francesca
AU  - Butterworth, Simon
AU  - Lockyer, Eloise
AU  - Song, Ok-Ryul
AU  - Pearson-Farr, Jennifer
AU  - Treeck, Moritz
TI  - <em>In vivo</em> CRISPR screens identify GRA12 as a transcendent secreted virulence factor across <em>Toxoplasma gondii</em> strains and mouse subspecies
AID  - 10.1101/2024.09.10.611481
DP  - 2024 Jan 01
TA  - bioRxiv
PG  - 2024.09.10.611481
4099  - http://biorxiv.org/content/early/2024/09/10/2024.09.10.611481.short
4100  - http://biorxiv.org/content/early/2024/09/10/2024.09.10.611481.full
AB  - 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.Competing Interest StatementThe authors have declared no competing interest.