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Theileria orientalis, the causative agent of oriental theileriosis, is an apicomplexan haemoparasite and is one of several tick-borne Theileria spp. infecting cattle. Unlike the highly pathogenic transforming Theileria species (T. annulata and T. parva) which induce uncontrolled lymphocytic proliferation, T. orientalis is a non-transforming strain exerting its major pathogenic effects via erythrocyte destruction. Clinical symptoms associated with oriental theileriosis are largely consequences of the underlying anaemia. Because of its non-transforming nature, T. orientalis was previously considered a benign parasite, however, in the recent years, clinical outbreaks of T. orientalis have been increasingly observed throughout Asia and Australasia. Recent rapid spread of clinical theileriosis has been linked to a pathogenic genotype of the parasite, genotype Ikeda (Type 2). The geographic distribution of clinical outbreaks correlates to the range of the major vector tick, Haemaphysalis longicornis, although other vectors and modes of transmission are possible. This review includes discussion of T. orientalis epidemiology, transmission, pathogenesis, treatment and control and provides an update on the taxonomy of this organism which is still under debate.

Mycoplasma hyopneumoniae is a genome-reduced, cell wall-less, bacterial pathogen with a predicted coding capacity of less than 700 proteins and is one of the smallest self-replicating pathogens. The cell surface of M. hyopneumoniae is extensively modified by processing events that target the P97 and P102 adhesin families. Here, we present analyses of the proteome of M. hyopneumoniae-type strain J using protein-centric approaches (one- and two-dimensional GeLC-MS/MS) that enabled us to focus on global processing events in this species. While these approaches only identified 52% of the predicted proteome (347 proteins), our analyses identified 35 surface-associated proteins with widely divergent functions that were targets of unusual endoproteolytic processing events, including cell adhesins, lipoproteins and proteins with canonical functions in the cytosol that moonlight on the cell surface. Affinity chromatography assays that separately used heparin, fibronectin, actin and host epithelial cell surface proteins as bait recovered cleavage products derived from these processed proteins, suggesting these fragments interact directly with the bait proteins and display previously unrecognized adhesive functions. We hypothesize that protein processing is underestimated as a post-translational modification in genome-reduced bacteria and prokaryotes more broadly, and represents an important mechanism for creating cell surface protein diversity.

P97 and P102 paralogues occur as endoproteolytic cleavage fragments on the surface of Mycoplasma hyopneumoniae that bind glycosaminoglycans, plasminogen, and fibronectin and perform essential roles in colonization of ciliated epithelia. We show that the P102 paralogue Mhp384 is efficiently cleaved at an S/T-X-F↓X-D/E-like site, creating P60384 and P50384. The P97 paralogue Mhp385 is inefficiently cleaved, with tryptic peptides from a 115 kDa protein (P115385) and 88 kDa (P88385) and 27 kDa (P27385) cleavage fragments identified by LC–MS/MS. This is the first time a preprotein belonging to the P97 and P102 paralogue families has been identified by mass spectrometry. The semitryptic peptide 752IQFELEPISLNV763 denotes the C-terminus of P88385 and defines the novel cleavage site 761L-N-V↓A-V-S766 in Mhp385. P115385, P88385, P27385, P60384, and P50384 were shown to reside extracellularly, though it is unknown how the fragments remain attached to the cell surface. Heparin- and cilium-binding sites were identified within P60384, P50384, and P88385. No primary function was attributed to P27385; however, this molecule contains four tandem R1 repeats with similarity to porcine collagen type VI (α3 chain). P97 and P102 paralogue families are adhesins targeted by several proteases with different cleavage efficiencies, and this process generates combinatorial complexity on the surface of M. hyopneumoniae.

Mycoplasma hyopneumoniae is a major, economically damaging respiratory pathogen. Although M. hyopneumoniae cells bind plasminogen, the identification of plasminogen-binding surface proteins and the biological ramifications of acquiring plasminogen requires further investigation. mhp182 encodes a highly expressed 102 kDa protein (P102) that undergoes proteolytic processing to generate surface-located N-terminal 60 kDa (P60) and C-terminal 42 kDa (P42) proteins of unknown function. We show that recombinant P102 (rP102) binds plasminogen at physiologically relevant concentrations (KD ~ 76 nM) increasing the susceptibility of plasmin(ogen) to activation by tissue-specific plasminogen activator (tPA). Recombinant proteins constructed to mimic P60 (rP60) and P42 (rP42) also bound plasminogen at physiologically significant levels. M. hyopneumoniae surface-bound plasminogen was activated by tPA and is able to degrade fibrinogen, demonstrating the biological functionality of M. hyopneumoniae-bound plasmin(ogen) upon activation. Plasmin(ogen) was readily detected in porcine ciliated airways and plasmin levels were consistently higher in bronchoalveolar lavage fluid from M. hyopneumoniae-infected animals. Additionally, rP102 and rP42 bind fibronectin with KDs of 26 and 33 nM respectively and recombinant P102 proteins promote adherence to porcine kidney epithelial-like cells. The multifunctional binding ability of P102 and activation of M. hyopneumoniae-sequestered plasmin(ogen) by an exogenous activator suggests P102 plays an important role in virulence.