Do Toxoplasma antigen-specific CD8 T cells confer protection and how are the antigens they recognize presented?
Through their production of IFNγ, CD8 T cells are important in conferring resistance against Toxoplasma. After an infection with Toxoplasma, both CD4 and CD8 T cells infiltrate the brain. How natural Toxoplasma epitopes are processed remains unknown, both on a molecular level and as they relate to the developmental stage of the parasite. Thus far only transgenic parasites expressing model antigens have been used as models. Obvious shortcomings of this approach include difficulties in controlling expression levels, localization of the antigen, and the reliance on TCR transgenics that recognize the model antigen. We have identified H-2Ld-restricted CD8 T cell epitopes derived from two distinct Toxoplasma proteins, dense granule protein GRA4 and rhoptry protein ROP7. GRA4-specific T cells are detected during acute infection, whereas T cells reactive to the ROP7 peptide persist during the chronic phase. T cells secrete protective IFNγ during both phases of infection. We have also identifie
