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Fundamental Roles of the Golgi-Associated Toxoplasma Aspartyl Protease, ASP5, at the Host-Parasite Interface.

Hammoudi PM, Jacot D, Mueller C, Di Cristina M, Dogga SK, Marq JB, Romano J, Tosetti N, Dubrot J, Emre Y, Lunghi M, Coppens I, Yamamoto M, Sojka D, Pino P, Soldati-Favre D - PLoS Pathog. (2015)

Bottom Line: We show that deletion of ASP5 causes a significant loss in parasite fitness in vitro and an altered virulence in vivo.Additionally, hypermigration of dendritic cells and bradyzoite cyst wall formation are impaired, critically impacting on parasite dissemination and persistence.Overall, the absence of ASP5 dramatically compromises the parasite's ability to modulate host signalling pathways and immune responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Molecular Medicine, Centre Médical Universitaire, University of Geneva, Geneva, Switzerland.

ABSTRACT
Toxoplasma gondii possesses sets of dense granule proteins (GRAs) that either assemble at, or cross the parasitophorous vacuole membrane (PVM) and exhibit motifs resembling the HT/PEXEL previously identified in a repertoire of exported Plasmodium proteins. Within Plasmodium spp., cleavage of the HT/PEXEL motif by the endoplasmic reticulum-resident protease Plasmepsin V precedes trafficking to and export across the PVM of proteins involved in pathogenicity and host cell remodelling. Here, we have functionally characterized the T. gondii aspartyl protease 5 (ASP5), a Golgi-resident protease that is phylogenetically related to Plasmepsin V. We show that deletion of ASP5 causes a significant loss in parasite fitness in vitro and an altered virulence in vivo. Furthermore, we reveal that ASP5 is necessary for the cleavage of GRA16, GRA19 and GRA20 at the PEXEL-like motif. In the absence of ASP5, the intravacuolar nanotubular network disappears and several GRAs fail to localize to the PVM, while GRA16 and GRA24, both known to be targeted to the host cell nucleus, are retained within the vacuolar space. Additionally, hypermigration of dendritic cells and bradyzoite cyst wall formation are impaired, critically impacting on parasite dissemination and persistence. Overall, the absence of ASP5 dramatically compromises the parasite's ability to modulate host signalling pathways and immune responses.

No MeSH data available.


Related in: MedlinePlus

ASP5 deletion affects in vivo virulence of type I and type II parasites.(A-B) C57Bl/6 mice were inoculated by intraperitoneal injection of 5.101 or 5.103 (A) type I parasite, and 105 or 106 (B) for type II parasites. Mice survival was monitored over time. Five animals were infected for each experiment.
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ppat.1005211.g005: ASP5 deletion affects in vivo virulence of type I and type II parasites.(A-B) C57Bl/6 mice were inoculated by intraperitoneal injection of 5.101 or 5.103 (A) type I parasite, and 105 or 106 (B) for type II parasites. Mice survival was monitored over time. Five animals were infected for each experiment.

Mentions: Type I parasites lacking GRA16 and GRA24 exhibit no decrease in virulence in mice, however the deletion of these genes in type II strain parasites has been reported to show reduced virulence [16, 17]. In light of this, type I and type II Δasp5 parasites and their parental lines were assessed for virulence upon intraperitoneal (i.p.) inoculation into groups of susceptible female C57Bl/6 mice. Mice had to be sacrificed 7 days after infection with 5.101RH parasites, whereas mice receiving the same inoculum of RHΔasp5 parasites survived for 13 days (Fig 5A). Despite this, upon inoculation of a larger number of parasites (5.103) no difference was observed between the two type I parasite lines (Fig 5A). This suggests that the delay observed during low dose infection could be explained by the reduced fitness observed in tissue culture. Mice infected with 106 type II parasites from both ME49 and ME49Δasp5 led to death of the animals over the acute phase of the infection (Fig 5B). In contrast, 80% of the mice infected with 105ME49Δasp5 survived the infection at day 40 whereas the control ME49 parasite line succumbed to infection within 7 to 13 days (Fig 5B). The type II Δasp5 in vivo phenotype therefore correlates with previous observations made with GRA16 and GRA24 deficient parasites [16, 17]. Seroconversion was assessed for the four surviving mice, which all display a positive serological profile (S5 Fig). Cyst biogenesis in vivo remains unassessed and will be further investigated.


Fundamental Roles of the Golgi-Associated Toxoplasma Aspartyl Protease, ASP5, at the Host-Parasite Interface.

Hammoudi PM, Jacot D, Mueller C, Di Cristina M, Dogga SK, Marq JB, Romano J, Tosetti N, Dubrot J, Emre Y, Lunghi M, Coppens I, Yamamoto M, Sojka D, Pino P, Soldati-Favre D - PLoS Pathog. (2015)

ASP5 deletion affects in vivo virulence of type I and type II parasites.(A-B) C57Bl/6 mice were inoculated by intraperitoneal injection of 5.101 or 5.103 (A) type I parasite, and 105 or 106 (B) for type II parasites. Mice survival was monitored over time. Five animals were infected for each experiment.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608785&req=5

ppat.1005211.g005: ASP5 deletion affects in vivo virulence of type I and type II parasites.(A-B) C57Bl/6 mice were inoculated by intraperitoneal injection of 5.101 or 5.103 (A) type I parasite, and 105 or 106 (B) for type II parasites. Mice survival was monitored over time. Five animals were infected for each experiment.
Mentions: Type I parasites lacking GRA16 and GRA24 exhibit no decrease in virulence in mice, however the deletion of these genes in type II strain parasites has been reported to show reduced virulence [16, 17]. In light of this, type I and type II Δasp5 parasites and their parental lines were assessed for virulence upon intraperitoneal (i.p.) inoculation into groups of susceptible female C57Bl/6 mice. Mice had to be sacrificed 7 days after infection with 5.101RH parasites, whereas mice receiving the same inoculum of RHΔasp5 parasites survived for 13 days (Fig 5A). Despite this, upon inoculation of a larger number of parasites (5.103) no difference was observed between the two type I parasite lines (Fig 5A). This suggests that the delay observed during low dose infection could be explained by the reduced fitness observed in tissue culture. Mice infected with 106 type II parasites from both ME49 and ME49Δasp5 led to death of the animals over the acute phase of the infection (Fig 5B). In contrast, 80% of the mice infected with 105ME49Δasp5 survived the infection at day 40 whereas the control ME49 parasite line succumbed to infection within 7 to 13 days (Fig 5B). The type II Δasp5 in vivo phenotype therefore correlates with previous observations made with GRA16 and GRA24 deficient parasites [16, 17]. Seroconversion was assessed for the four surviving mice, which all display a positive serological profile (S5 Fig). Cyst biogenesis in vivo remains unassessed and will be further investigated.

Bottom Line: We show that deletion of ASP5 causes a significant loss in parasite fitness in vitro and an altered virulence in vivo.Additionally, hypermigration of dendritic cells and bradyzoite cyst wall formation are impaired, critically impacting on parasite dissemination and persistence.Overall, the absence of ASP5 dramatically compromises the parasite's ability to modulate host signalling pathways and immune responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Molecular Medicine, Centre Médical Universitaire, University of Geneva, Geneva, Switzerland.

ABSTRACT
Toxoplasma gondii possesses sets of dense granule proteins (GRAs) that either assemble at, or cross the parasitophorous vacuole membrane (PVM) and exhibit motifs resembling the HT/PEXEL previously identified in a repertoire of exported Plasmodium proteins. Within Plasmodium spp., cleavage of the HT/PEXEL motif by the endoplasmic reticulum-resident protease Plasmepsin V precedes trafficking to and export across the PVM of proteins involved in pathogenicity and host cell remodelling. Here, we have functionally characterized the T. gondii aspartyl protease 5 (ASP5), a Golgi-resident protease that is phylogenetically related to Plasmepsin V. We show that deletion of ASP5 causes a significant loss in parasite fitness in vitro and an altered virulence in vivo. Furthermore, we reveal that ASP5 is necessary for the cleavage of GRA16, GRA19 and GRA20 at the PEXEL-like motif. In the absence of ASP5, the intravacuolar nanotubular network disappears and several GRAs fail to localize to the PVM, while GRA16 and GRA24, both known to be targeted to the host cell nucleus, are retained within the vacuolar space. Additionally, hypermigration of dendritic cells and bradyzoite cyst wall formation are impaired, critically impacting on parasite dissemination and persistence. Overall, the absence of ASP5 dramatically compromises the parasite's ability to modulate host signalling pathways and immune responses.

No MeSH data available.


Related in: MedlinePlus