GRA12 is a common virulence factor across Toxoplasma gondii strains and mouse subspecies

• Published in: Nature communications Vol. 16; no. 1; pp. 3570 - 17
• Main Authors: Torelli, Francesca, Butterworth, Simon, Lockyer, Eloise, Matias, Ana N., Hildebrandt, Franziska, Song, Ok-Ryul, Pearson-Farr, Jennifer, Treeck, Moritz
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16.04.2025; Nature Publishing Group; Nature Portfolio
• Subjects: 13/106; 13/109; 13/51; 14/1; 14/19; 14/34; 14/63; 631/250/2161; 631/326/417/2546; 64; 64/60; Animals; Clearances; CRISPR; CRISPR-Cas Systems; Female; Genotypes; Host-Parasite Interactions; Humanities and Social Sciences; Immune clearance; Infections; Interferon-gamma; Macrophages; Macrophages - immunology; Macrophages - parasitology; Mice; Mice, Inbred C57BL; multidisciplinary; Necrosis; Parasites; Parasitophorous vacuole; Proteins; Protozoa; Protozoan Proteins - genetics; Protozoan Proteins - metabolism; Science; Science (multidisciplinary); Screens; Secretome; Strains (organisms); Toxoplasma; Toxoplasma - genetics; Toxoplasma - metabolism; Toxoplasma - pathogenicity; Toxoplasma gondii; Toxoplasmosis - parasitology; Toxoplasmosis, Animal - immunology; Toxoplasmosis, Animal - parasitology; Vacuoles; Virulence; Virulence factors; Virulence Factors - genetics; Virulence Factors - metabolism; γ-Interferon
• ISSN: 2041-1723; 2041-1723
• 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. CRISPR screens reveal Toxoplasma ’s GRA12 as a strain- and mouse species-transcendent virulence factor. GRA12 protects parasites from IFNγ-activated macrophage clearance and parasitophorous vacuole collapse.