An In Silico Gene Construct Designing to Express the Chimeric Protein CTB-PaD4

Natural anthrax is rare among humans، but since this bacterium has the potential to be used as a biological weapon، efforts to produce a vaccine against the bacteria are increasing. Combination of the Cholera toxin B subunit (CTB) with other antigens can produce a strong antibody response and be used as a vaccine. This study aimed to link the gene sequence ctB and paD4 and predicate three-dimensional structure of the Chimeric protein. In this study، first، Nucleotide sequences were obtained from NCBI database and optimized. Sequences were fused together by appropriate amino acid linker in order to find the best epitope exposing chimeric antigen. After Protein half-life and instability index were determined، and then the prediction of the secondary structure and the three-dimensional structure was analyzed. Finally immunodominant linear B cells were also settled. Codons were changed with respect to codon bias of E. coli and the content of C + G was converted to an optimal level. Inappropriate structures of RNA were removed. Howerver، These changes led to a prolonged half-life and increased mRNA expression of the recombinant protein. Secondary structures and three-dimensional structure was specified. EAAAK linker could prevent the protein domain interactions well. Due to the changes over gene encoding of this protein، Silico analysis represented that Nucleotide sequence can have a high expression in E. coli. The predicted Three-dimensional structures of proteins were evaluated by online software and the best one was choosen. Optimized chimeric sequence can be a good candidate in immunogenicity study to produce an effective vaccine.