[Prediction and Identification of Immunodominant Linear B Cell Epitopes in the Nucleocapsid Protein of SFTSV].

Abstract

In order to identify immunodominant linear B cell epitopes in the nucleocapsid protein N of severe fever with thrombocytopenia syndrome virus(SFTSV),bioinformatics programs were used to analyze antigenicity, hydrophilicity and surface probability of the amino acid sequence and predict possible linear B cell epitopes. PyMOL software was used to analyze the distribution of linear B cell epitopes in nucleocapsid protein N based on its crystal structure. Corresponding peptides were synthesized and examined in peptide enzyme-linked immunosorbent assay(Peptide-ELISA)individually to check whether they reacted with sera from SFTSV-infected patients. As a result, a total of six potential linear B cell epitopes were predicted as the following: A(40-KKLKETGGDDWVKDTK-55), B(71-ASGKMSNSGSKRL-83), C(94-ERAETRL-100),D(135-LKVENYPP-142),E(157-GVSEATT-163)and F(184-KMRGASKTEVYNSFRDP-200).All epitopes were located on the surface of the nucleocapsid protein N and contained flexible loops. Each of the six synthetic peptides reacted positively with sera from SFTSV-infected patients and were identified as immunodominant linear B cell epitopes. Linear regression analysis showed a positive correlation between each peptide-ELISA and commercialized N protein-based EIA. In this study, immunodominant linear B cell epitopes from the nucleocapsid protein N of SFTSV were successfully predicted and confirmed. These findings may help to establish the molecule basis of specific antigenicity and disease diagnosis.