Theileria equi merozoite antigen-2 interacts with actin molecule of equine erythrocyte during their asexual development

Abstract

Theileria equi is a tick-transmitted intraerythrocytic protozoan parasite in equids. Equine merozoite antigen (EMA)-1 and EMA-2 of T. equi have been identified as immunodominant proteins co-expressed on the surface of extra-erythrocytic merozoites. Additionally, only the EMA-2 is shed into the cytoplasm of infected erythrocyte or inside the erythrocytic membrane during their early developmental stage. In this study, we initially performed West-Western blot analysis on Triton X-100-insoluble erythrocytic skeleton collected from a healthy horse, using a glutathione S-transferase (GST)-tagged recombinant EMA- 1t or EMA-2t of T. equi. The results indicated positive interactions of actin and band 4.1 molecules in the equine erythrocytic skeleton only with the recombinant EMA-2t. Subsequently, we carried out GST pull-down assay using the recombinant antigens (as above) against solubilized lysate of equine erythrocytic skeleton, and confirmed the co-precipitation of actin molecule with EMA-2t, but not with the EMA- 1t. The interaction of EMA-2 with host erythrocytic actin indicated its role in the pathobiology of T. equi infection within host erythrocytes.