CD8 +T cell recognition of neuronal cysts during chronic Toxoplasma gondiiinfection

Abstract

Abstract The parasite Toxoplasma gondiiestablishes persistent infection within neurons by forming cysts that harbor latent form bradyzoites. The ability to form cysts is dependent on the parasite transcription factor BFD1 and, given the presence of a thick cyst wall, it was previously thought that cysts were protected from immune recognition. However, the generation of a BAG1-OVA parasite line, in which OVA protein expression is restricted to bradyzoites, revealed that in vivo infection elicited the activation and expansion of OVA-specific OT-I CD8 +T cells. To determine whether endogenous CD8 +T cells can recognize natural cyst-derived antigens and potentially participate in cyst control, in vitro T cell recognition assays were performed using a BFD1-inducible line of parasites that form in vitro cysts. In these assays, CD8 +T cells isolated from T. gondii-infected mice recognized both infected murine fibroblasts and neurons containing cysts. These studies indicate that cyst-specific T cells are present during infection and future studies will explore if any parasite antigens transported beyond the cyst wall can be presented by neurons for T cell recognition. Supported by NIH grant R01 AI157247-01