Investigation of carbohydrate-based molecules of Theileria parva parasites

Theileria parva (Tp), the causative agent of East Coast Fever, poses a major threat to Bos taurus cattle in sub-Saharan Africa. Progress towards a stable, affordable, cross-protective subunit vaccine covering more than one major histocompatibility complex (MHC)-presented Tp antigen has been hindered by the limited knowledge of antigens. Given the importance of glycoconjugates in protozoan pathogen biology, especially during the invasion process, we investigated the glycosylation potential of Tp. Screening of Tp Muguga (TpM) schizonts with C-type lectin (-like) receptors showed that ruminant, but not murine, Macrophage C-type Lectin (MCL) recognises the parasite. Binding of ruminant MCL to TpM schizonts suggested the presence of carbohydrate-associated parasite surface molecules. Lectin staining further suggested the presence of terminal GlcNAc residues on the parasite surface which is in alignment with the identification of a minimal N-glycosylation machinery in TpM schizonts. LC-MS/MS analysis of HILIC HPLC and lectin-enriched peptides from parasite protein fractions yielded eight predicted N-glycopeptides and two predicted O-glycopeptides. Putative parasite O-glycans were assigned with high confidence, yet assignments of putative N-glycans to parasite proteins were less confident. Our data provide first insights into potential TpM glycoconjugates while confirmation of glycan composition and assignment requires additional analyses.