基于免疫信息学技术的雏沙门菌多表位疫苗构建OACSTPCD

[Objective]This study was aimed to design multi-epitope vaccine against IpaJ protein of Salmonella Pullorum and provide a new vaccine for purifying chicken dysentery.[Method]In this study,IEDB was used to predict the major histocompatibility complex class Ⅰ(MHC Ⅰ)molecular binding epitopes of Salmonella Pullorum IpaJ protein in T lymphocytes.NetMHCIIpan 4.0 Server was used to predict T lymphocytes MHC Ⅱ molecular binding epitopes.B lymphocyte epitope was predicted by IEDB.After the antigenicity of the selected epitopes was evaluated by VaxiJen v 2.0,the qualified epitopes were concatenated into multi-epitope vaccine by flexible linker.Antigenicity,physicochemical properties,N-glycosylation sites,secondary structure and tertiary structure of the constructed multi-epitope vaccine were predicted.Molecular docking was used to evaluate the binding ability of the multi-epitope vaccine to the immune receptor.Immune simulation was used to evaluate the immune effect of the multi-epitope vaccine.Finally,the codon was optimized for cloning expression.[Result]After screening,the constructed multi-epitope vaccine MEV-IpaJ contained 4 MHC Ⅰ,4 MHC Ⅱ and 8 B lymphocyte epitope dominance.The relative molecular weight of the multi-epitope vaccine MEV-IpaJ was 28.18 ku,which was a stable hydrophilic protein and had good antigenicity.There were four potential N-glycoylation sites,including a-helix,extended strand,beta turn and random coil accounted for 20.38％,19.23％,8.08％and 52.31％,respectively.Ramachandran mapping of tertiary structure showed that the dominant region contained 89.9％of the residual base,and the residual base of the dominant region increased to 94.0％after refinement.The mapping of tertiary structure prominent epitope also proved that the multi-epitope vaccine had good immunogenicity,and molecular docking showed that the MEV-IpaJ could dock with Toll-like receptor 2(TLR2)and TLR4 protein molecules.The results of immune simulation showed that the MEV-IpaJ had a good immune response and could improve the expression of some cytokines.Codon optimization ensured the efficient and stable expression of the MEV-IpaJ in E.coli K12 expression system.[Conclusion]The constructed multi-epitope vaccine MEV-IpaJ could be effectively expressed and might induce strong T cell and B cell immune responses.This study provided a new method for the design of multi-epitope vaccine of Salmonella Pullorum,and provided theoretical basis and data support for the research and development of multi-epitope vaccine of Salmonella Pullorum.