CD8 Tcells play a key role in defense against the intracellular parasite Toxoplasma, but why certain CD8 responses are more potent than others is not well understood. Here, we describe a parasite antigen, ROP5, that elicits a CD8 Tcell response in genetically susceptible mice. ROP5 is secreted via parasite organelles termed rhoptries that are injected directly into host cells during invasion, whereas the protective, dense-granule antigen GRA6 is constitutively secreted into the parasitophorous vacuole. Transgenic parasites in which the ROP5 antigenic epitope was targeted for secretion through dense granules led to enhanced CD8 Tcell responses, whereas targeting the GRA6 epitope to rhoptries led to reduced CD8 responses. CD8 Tcell responses to the dense-granule-targeted ROP5 epitope resulted in reduced parasite load in the brain. These data suggest that the mode of secretion affects the efficacy of parasite-specific CD8 Tcell responses.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)