Table 2 The main proteins of Toxoplasma gondii identified as virulence factors and their interaction with the immune system
From: Genetic diversity of Toxoplasma gondii in South America: occurrence, immunity, and fate of infection
Proteins | Source | Virulence mechanisms and immunological importance | References |
|---|---|---|---|
Rhoptry protein 5 (ROP5) | Rhoptries | Regulation of ROP18 catalytic activity, forming a ROP5/ROP18 complex Blocking of interferon (IFN)-γ-mediated macrophage microbicidal activity Limits antigen presentation in macrophages and dendritic cells | |
ROP7 | Interacts with the NACHT domain of NLR family pyrin domain-containing 3 (NLRP3) and promotes inflammasome hyperactivation and induction of interleukin (IL)-1β | [66] | |
ROP16 | Phosphorylation of signal transducer and activator of transcription protein 3 (STAT3) and STAT6 and induction of IL-12 and IFN-γ-mediated inflammatory response | ||
ROP18 | Downregulation of the macrophage production of IL-16, TNF-α and IL-12 by phosphorylation of p65 domain of nuclear factor kappa B (NF-κB) Suppression of antigen presentation mechanisms in macrophages and dendritic cells | ||
GRA3 | Dense granules | Regulation of the antigen presentation mechanisms in an IFN-γ or cell-independent manner | [57] |
GRA6 | Regulation of the activation of nuclear factor of activated T cells 4 (NFAT4) in a strain-specific manner, modulating the expression of C-X-C motif chemokine ligand 2 (CXCL2) and C-C motif chemokine ligand 2 (CCL2) and the recruitment of neutrophils | [76] | |
GRA7 | Interacts with the ROP5/ROP18 complex, binding directly to ROP5 to promote the phosphorylation of immune-regulated guanosine triphosphatase 6 (IRG6) and inactivation of IRG-mediated resistance system | [73] | |
GRA12 | Confers resistance to IFN-γ-mediated immune response, leading to better parasite survival and establishment of infection in a strain-specific manner | ||
GRA15 | Activation of NF-κB via TNF receptor-associated protein 6 (TRAF6) Induction of the inflammasome activation pathway and contributes to IL-1β, IL-12 and TNF-α production | ||
GRA24 | Act as an activator of the immune response, modulating IL-12, IL-1β and TNF-α production via mitogen-activated protein kinase (MAPK) activation and the NF-κB pathway, independently of MYD88 innate immune signal transduction adaptor | ||
GRA25 | Modulation of CCL2 production by macrophages and contributes to efficient parasite survival | [72] |