Design of Multi-epitope Vaccines for Avian Pathogenic Escherichia coli O1 and O78 Serotypes Based on Subtractive Proteomics and Reverse Vaccinology
[Objective]This study was aimed to design a multi-epitope vaccine(MEV)against avian pathogenic Escherichia coli(APEC)O1 and O78 serotypes,laying a foundation for the development of new vaccines for APEC.[Method]This study combined subtraction proteomics and reverse vaccinology.Redundant and non-similar proteins in the protein sequences of APEC O1 and O78 were removed using CD-HIT and BLASTP tools.Similar proteins in APEC O1 and O78 were removed by BLASTP and compared with reference proteomes of chicken,retaining non-homologous proteins.Essential toxigenic proteins were screened using DEG,VFDB,etc.databases.Candidate proteins were selected using PSORTb and VaxiJen v 2.0.T-cell major histocompatibility complex(MHC)class Ⅰ and Ⅱ molecule-binding epitopes were predicted using NetCTL 1.2 and NetMHCⅡ pan 4.0,and B-cell epitopes were predicted using IEDB.Multi-epitope vaccine were evaluated for antigenicity by VaxiJen v 2.0,and the qualified epitopes were linked together by flexible linkers to form a multi-epitope vaccine.The antigenicity,physical and chemical properties,N-glycosylation sites,secondary structure and tertiary structure of the constructed multi-epitope vaccine were predicted.The binding ability of the multi-epitope vaccine to immune receptors was evaluated by molecular docking,and the immune effect was evaluated by immune simulation.Finally,the codons were optimized for cloning and expression.[Result]After screening,12 MHC Ⅰ,12 MHC Ⅱ and 12 B lymphocyte epitope-dominant epitopes were selected to construct the multi-epitope vaccine MEV-O1O78.The molecular mass of the multi-epitope vaccine MEV-O1O78 was 69.81 ku,a stable hydrophilic protein with good antigenicity,containing 7 potential N-glycosylation sites.In the secondary structure,alpha-helix,extended chain and random coil accounted for 7.93％,10.81％and 81.27％,respectively.The Ramachandran plot of the tertiary structure showed that the epitope-rich region contained 95.6％of the residues.The immune simulation results showed that multi-epitope MEV-O1O78 could induce good humoral immunity and enhance the expression of some cytokines.The codon optimization ensured that the designed multi-epitope MEV-O1O78 was efficiently and stably expressed in the Escherichia coli K12 expression system.[Conclusion]In this study,the APEC O1 and O78 multi-epitope vaccine MEV-O1O78 containing 36 dominant epitopes was successfully designed,which provided theoretical basis and data support for the development of multi-epitope vaccine for avian pathogenic colibacillosis.
万方数据
维普
