Elucidation and validation of single chain fragment variation against 12 kDa ES protein from Toxoplasma gondii

Abstract

IntroductionToxoplasma gondii is the causative agent of toxoplasmosis which has infected one third of the world population. This disease affects the survival of fetuses and immunosuppressed patients. Thus, early detection is crucial for disease management and therapy. Due to the lack of reliable diagnostic tests, we carried out a study on a highly antigenice 12 kDa excretory-secretory (ES) protein previously discovered from T. gondii against a single chain fragment variation (scFv). Elucidating the scFv structure and validating it against the 12 kDa ES protein is essential to design a specific antibody in order to develop an antigen-based diagnostic test. ObjectivesTo study the interactions between scFv against 12 kDa ES protein. MethodsscFv structure was modeled using MODELLER. Docking simulation was performed to study the interaction of scFv with ES epitopes. Results & DiscussionThe modeled structure possesses heavy chains and light chains with 3 CDR regions each. The heavy chain and light chain regions were connected by a highly flexible disulfide bridge. Results showed that the epitopes of ES protein were docked within the CDR regions of modeled scFv. Hot spot scFv residues have been identified for further mutagenesis. ConclusionThe modeled scFv structure has the potential to be optimized to improve its binding affinity for the future development of antigen-based toxoplasmosis diagnosis.