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Prediction of immunogenicity: an in silico approach applied to the recombinant protein Amblyomin-X, a promising antitumor agent

Silva BAVG, Chudzinski-Tavassi AM, Pasqualoto KFM

Laboratório de Bioquímica e Biofísica, Instituto Butantan, Brasil

Introduction: Immunogenicity is a significant problem associated with protein therapeutics in order to avoid the development of treatment resistance and potentially life-threatening immune responses. It can be predicted in advance by in silico approaches, for instance, which allow the identification of sequences within a therapeutic protein that, when processed by T-cells, could elicit an immune response. In our lab, the salivary glands transcriptome of the adult Amblyomma cajennense tick was characterized by expressed sequence tags (EST), and a transcript that encodes for a tissue factor pathway inhibitor (TFPI)-like protein with unique structure was found. The recombinant protein, named Amblyomin-X, has been reported as a promising antitumor, and its immunogenic profile prediction may also help the understanding of experimental findings.  
  Objectives: The goal was investigate the immunogenic profile of Amblyomin-X by applying in silico tools (SYFPEITHI and IEDB data banks, and molecular docking method), considering both major histocompatibility complex pathways, MHC class I and MHC class II.
  Methods: The T-cell response to a protein therapeutic antigen is dependent on the binding of T-cell epitopes to MHC, presentation of the MHC:epitope complex at the cell surface, and recognition of that complex by either an effector or regulatory T-cells (Treg), an interaction that can be evaluated in MHC or human leucocyte antigen (HLA) binding assays. SYFPEITHI and IEDB data banks for predictors of human proteasomal cleavage, TAP transport, and MHC binding were used in order to produce an overall score for each peptide’s intrinsic potential of being a T cell epitope. After that, the peptide sequences better classified were also docked into the three-dimensional (3D) structure of MHC binding site (CLC Drug Discovery Workbench 1.5.1, Quiagen Aarhus A/S).  In addition, the binding interactions regarding the molecular recognition by T-cells were explored through the molecular docking in the MHC I/T-cell complex. 
  Results and Discussion: Regarding Ambyomin-X sequence, four peptide sequences were identified as potential MHC class I epitopes and five peptide sequences as potential MHC class II. Thus, the in silico approach applied herein can be considered as useful routine to identify the most potential epitopes and drive the synthesis of the promising peptides to be further experimentally assayed.

Supported by BNDES

2 - BIOCHEMISTRY 21th Annual Scientific Meeting of Instituto Butantan.