p97/VCP targets Toxoplasma gondii vacuoles for parasite restriction in interferon-stimulated human cells

Abstract

Infection with the parasite Toxoplasma gondii leads to production of interferon gamma (IFN{gamma}) that stimulates cells to upregulate defence proteins targeting the parasite for cell intrinsic elimination or growth restriction. Various host defence mechanisms operate at the parasitophorous vacuole (PV) in different human cell types leading to PV disruption, acidification, or membrane envelopment. Ubiquitin and p62 are players in all human host control mechanisms of Toxoplasma, but other unifying proteins have not been identified. Here, we show that p97/valosin-containing protein (VCP), as well as its associated proteins ANKRD13A and UBXD1 control Toxoplasma infection while recruited to the PV in IFN{gamma}-stimulated endothelial cells. Convergent deposition of ANKRD13A, p97/VCP and UBXD1 onto the same vacuole is dependent on vacuolar ubiquitination and observed within 2h post-infection. ANKRD13A, p97/VCP and UBXD1 all drive the acidification mechanism of the vacuole, which is the IFN{gamma}-dependent control pathway of Toxoplasma in endothelial cells. We assessed p97/VCP in Toxoplasma control in various human cells and demonstrate that p97/VCP is a universal IFN{gamma}-dependent host restriction factor targeting the Toxoplasma PV in epithelial (HeLa) and endothelial cells (HUVEC), fibroblasts (HFF) and macrophages (THP1).