Identification of a Novel Interaction between Theileria Prohibitin (TaPHB-1) and Bovine RuvB-Like AAA ATPase 1

Theileriosis is a tick-borne disease caused by Theileria annulata, an intracellular parasite that belongs to the phylum Apicomplexa. The infective forms of the parasite to cattle are sporozoites that are introduced into the host when the infected ticks take a blood meal. The sporozoites selectively invade bovine B cells, macrophages, or monocytes, leading to their cellular transformation. The parasite factors involved in the host cell transformation are not well explored. In pursuit of this, we revisited the probable secretome of the parasite and, following a stringent downscaling criterion, have identified Theileria prohibitin (TaPHB-1) as one of factors secreted into the host cells. Interestingly, in infected cells, TaPHB-1 localized both on the parasite surface and in the host cytoplasm, and independent approaches such as coimmunoprecipitation, yeast two-hybrid screening (Y2H), and liquid chromatography-tandem mass spectrometry (LC-MS/MS) confirmed RuvB-like AAA ATPase 1 (RUVBL-1) as one of its interacting partners. Further, the T. annulata infection does not affect the localization of bovine prohibitin. Mitigating the expression of bovine RUVBL-1 precluded the translocation of TaPHB-1 in the host cell cytoplasm without affecting the host cell viability. Taken together, we report for the first time a unique interaction of TaPHB-1 with bovine RUVBL-1 that is likely needed to cause cancer-like hallmarks during theileriosis. IMPORTANCE Theileria annulata is an apicomplexan parasite that causes tropical theileriosis in cattle. It is the only eukaryotic pathogen able to cause cellular transformation of host cells yielding a cancer-like phenotype. The parasite factors responsible for the transformation of the host cell are largely unknown. This study demonstrates for the first time the partial role of Theileria prohibitin (TaPHB-1) in maintaining the transformed state of the host cell and its interaction with RuvB-like AAA ATPase 1 (RUVBL-1) in a T. annulata-infected bovine cell line. Interestingly, the knockdown of bovine RUVBL-1 rendered the parasites metabolically inactive, implying that the identified interaction is critical for parasite survival. This study contributes to our understanding the Theileria-host interactions and offers scope for novel therapeutic interventions to control theileriosis.