Altiratinib Targets PRP4K in Theileria annulata , Disrupting RNA Processing and Inducing Apoptosis in Infected Cells

Tropical theileriosis, driven by Theileria annulata , poses a critical threat to livestock health, particularly in the face of rising resistance to buparvaquone, the primary and only treatment option. This study investigates the therapeutic potential and mechanistic actions of Altiratinib, a spliceosome-associated kinase inhibitor, in targeting T . annulata -infected bovine cells. Through bioinformatic and molecular docking analyses, Altiratinib was shown to selectively bind conserved catalytic motifs of PRP4K homologs in T. annulata (TA21325) and Theileria parva (TpMuguga_01g00303), with reduced affinity observed upon L715F mutation. In vitro assays confirmed potent anti-parasitic activity against both buparvaquone-sensitive and - resistant strains, while sparing uninfected peripheral blood mononuclear cells. Proteomic profiling revealed disruption of host and parasite RNA splicing and translation machinery. Altiratinib further induced G1-phase arrest, inhibited cMET-mediated signaling, and suppressed DNA synthesis. Additionally, it triggered oxidative stress, mitochondrial depolarization, and ROS-mediated DNA damage, culminating in p53 activation and caspase-9-driven intrinsic apoptosis. Downregulation of TaSP expression reinforced its selective targeting of parasite-infected cells. These findings highlight Altiratinib’s promise as a directed therapeutic for tropical theileriosis and other piroplasm infections, offering a novel avenue to combat drug-resistant strains and meriting further preclinical evaluation.