Host ER–parasitophorous vacuole interaction provides a route of entry for antigen cross-presentation in<i>Toxoplasma gondii</i>–infected dendritic cells

Goldszmid, Romina S.; Coppens, Isabelle; Lev, Avital; Caspar, Patricia; Mellman, Ira; Sher, Alan

doi:10.1083/jcb1842oia4

Cited by 10 publications

(12 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous studies on parasite Ags presented by MHC-II molecules investigated mainly the process after parasite invasion or death (35,36). The impact of Ag localization on immunogenicity has been studied with protozoan parasites.…”

Section: Discussionmentioning

confidence: 99%

Transgenic Eimeria tenella Expressing Enhanced Yellow Fluorescent Protein Targeted to Different Cellular Compartments Stimulated Dichotomic Immune Responses in Chickens

Huang

Zou

et al. 2011

The Journal of Immunology

View full text Add to dashboard Cite

Eimeria tenella, one of the seven species of chicken coccidia, elicits protective immunity against challenge infection with both homologous and heterologous strains. We endeavor to use recombinant E. tenella as a vaccine vehicle for expressing and delivering pathogen Ags and investigate immune responses against these foreign Ags. In this study, two lines of transgenic E. tenella expressing a model Ag, enhanced yellow fluorescent protein (EYFP), targeted to the micronemes and to the cytoplasm of the recombinant parasites were constructed to study the impact of Ag compartmentalization on immunogenicity. The MTT assay, intracellular cytokine staining, and real-time PCR were performed to detect the EYFP-specific proliferation and effector functions of splenic lymphocytes of immunized chickens. ELISA was used to measure anti-EYFP IgG and IgA responses. The results showed that both lines of transgenic parasites stimulated EYFP-specific lymphocyte proliferation and IFN-γ expression in CD4 and CD8 T cells, whereas a higher level of Ag-specific lymphocyte proliferation was elicited by the transgenic line expressing microneme-targeted EYFP. Furthermore, this line stimulated stronger IgA response than the one expressing cytoplasm-targeted EYFP after the second immunization. Our findings are encouraging for further investigation of the effect of Ag compartmentalization in transgenic Eimeria on immunogenicity and for the development of a eukaryotic vaccine vector using genetically modified Apicomplexa parasites.

show abstract

Section: Discussionmentioning

confidence: 99%

Transgenic Eimeria tenella Expressing Enhanced Yellow Fluorescent Protein Targeted to Different Cellular Compartments Stimulated Dichotomic Immune Responses in Chickens

Huang

Zou

et al. 2011

The Journal of Immunology

View full text Add to dashboard Cite

show abstract

“…In contrast, immunization with T. gondii extracts or killed noninvasive intact parasites does not elicit significant immunity to reinfection with T. gondii (2,40). Only actively infected host cells have been shown to prime CD8 ϩ T-cell-dependent immunity in T. gondii infection (10,20,21).…”

mentioning

confidence: 98%

Avirulent Uracil Auxotrophs Based on Disruption of Orotidine-5′-Monophosphate Decarboxylase Elicit Protective Immunity to Toxoplasma gondii

Fox¹,

Bzik²

2010

Infect Immun

125

View full text Add to dashboard Cite

The orotidine-5-monophosphate decarboxylase (OMPDC) gene, encoding the final enzyme of the de novo pyrimidine biosynthesis pathway, was deleted using Toxoplasma gondii KU80 knockouts to develop an avirulent nonreverting pyrimidine auxotroph strain. Additionally, to functionally address the role of the pyrimidine salvage pathway, the uridine phosphorylase (UP) salvage activity was knocked out and a double knockout of UP and OMPDC was also constructed. The nonreverting ⌬OMPDC, ⌬UP, and ⌬OMPDC ⌬UP knockout strains were evaluated for pyrimidine auxotrophy, for attenuation of virulence, and for their ability to elicit potent immunity to reinfection. The ⌬UP knockout strain was replication competent and virulent. In contrast, the ⌬OMPDC and ⌬OMPDC ⌬UP strains were uracil auxotrophs that rapidly lost their viability during pyrimidine starvation. Replication of the ⌬OMPDC strain but not the ⌬OMPDC ⌬UP strain was also partially rescued in vitro with uridine or cytidine supplementation. Compared to their hypervirulent parental type I strain, the ⌬OMPDC and ⌬OMPDC ⌬UP knockout strains exhibited extreme attenuation in murine virulence (ϳ8 logs). Genetic complementation of the ⌬OMPDC strain using a functional OMPDC allele restored normal replication and type I parental strain virulence phenotypes. A single immunization of mice with either the live critically attenuated ⌬OMPDC strain or the ⌬OMPDC ⌬UP knockout strain effectively induced potent protective immunity to lethal challenge infection. The avirulent nonreverting ⌬OMPDC and ⌬OMPDC ⌬UP strains provide new tools for the dissection of the host response to infection and are promising candidates for safe and effective Th1 vaccine platforms that can be easily genetically engineered.

show abstract

“…While electron micrographs suggested that the IVN might be primarily parasitic in origin (12,15), no direct biochemical analysis has been reported, and its true origin has been a mystery. Tantalizingly, host endoplasmic reticulum (ER) proteins also appear to have access to the vacuolar space, and in particular, host glucose-6-phosphatase has been observed in the posterior membrane-like material seen in the nascent PV described above (7,11). This suggests that there might be a flow of lipids between the host ER and the PVM but gives no hint as to the magnitude of that flow and the relative contributions that host and parasite lipids might each represent within the IVN.…”

mentioning

confidence: 99%

Evidence for Host Cells as the Major Contributor of Lipids in the Intravacuolar Network of Toxoplasma-Infected Cells

Caffaro

Boothroyd

2011

Eukaryot Cell

View full text Add to dashboard Cite

The intracellular parasite Toxoplasma gondii develops inside a parasitophorous vacuole (PV) that derives from the host cell plasma membrane during invasion. Previous electron micrograph images have shown that the membrane of this vacuole undergoes an extraordinary remodeling with an extensive network of thin tubules and vesicles, the intravacuolar network (IVN), which fills the lumen of the PV. While dense granule proteins, secreted during and after invasion, are the main factors for the organization and tubulation of the network, little is known about the source of lipids used for this remodeling. By selectively labeling host cell or parasite membranes, we uncovered evidence that strongly supports the host cell as the primary, if not exclusive, source of lipids for parasite IVN remodeling. Fluorescence recovery after photobleaching (FRAP) microscopy experiments revealed that lipids are surprisingly dynamic within the parasitophorous vacuole and are continuously exchanged or replenished by the host cell. The results presented here suggest a new model for development of the parasitophorous vacuole whereby the host provides a continuous stream of lipids to support the growth and maturation of the PVM and IVN.Toxoplasma gondii is an apicomplexan parasite that infects almost any warm-blooded animal. This ubiquitous parasite is able to proliferate inside the host cell within a unique and dynamic parasitophorous vacuole (PV). This vacuole is established during invasion initially as an invagination of the host cell plasma membrane that surrounds the invading parasite and then pinches off to create a PV (18). During this process, parasite secretory organelles, called dense granules, discharge specific protein factors (GRAs) that remodel the vacuole into a sheltered niche for the parasite.Toxoplasma's ability to acquire essential nutrients from its environment is fundamental to its intracellular lifestyle. It has been postulated that Toxoplasma gains access to various host metabolites (Ͻ1,300 Da) via diffusion through small pores in the PV membrane (PVM) (14). While no direct connection between the PV and the host vesicular transport system has been observed (13), Toxoplasma incorporates low-density lipoprotein (LDL)-derived cholesterol from host endolysosomes (4). Host mitochondria are also recruited efficiently to the cytosolic face of the PV soon after invasion, allowing Toxoplasma to scavenge host lipoic acid (5, 16).In addition to nutrient acquisition from the host cytosol, Toxoplasma facilitates its intracellular lifestyle by actively remodeling the PV. The purpose of this remodeling and the origin of the lipid constituents it uses have not been established. Electron micrographs of the Toxoplasma PV show membrane-like material within the PV and close to the posterior end of the parasites at very early times during invasion (15). A complex of secreted GRA2/GRA4/GRA6 proteins interacts with this material and seems to be required for its reorganization and tubulation (9, 12). Later during infection, similar thin tubul...

show abstract

Host ER–parasitophorous vacuole interaction provides a route of entry for antigen cross-presentation inToxoplasma gondii–infected dendritic cells

Cited by 10 publications

References 1 publication

Transgenic Eimeria tenella Expressing Enhanced Yellow Fluorescent Protein Targeted to Different Cellular Compartments Stimulated Dichotomic Immune Responses in Chickens

Transgenic Eimeria tenella Expressing Enhanced Yellow Fluorescent Protein Targeted to Different Cellular Compartments Stimulated Dichotomic Immune Responses in Chickens

Avirulent Uracil Auxotrophs Based on Disruption of Orotidine-5′-Monophosphate Decarboxylase Elicit Protective Immunity to Toxoplasma gondii

Evidence for Host Cells as the Major Contributor of Lipids in the Intravacuolar Network of Toxoplasma-Infected Cells

Contact Info

Product

Resources

About