Bioinformatic Analysis of Different Fusions of ipaD, PA20 and CTxB Antigens: A Preliminary Analysis for Vaccine Design

ipaD gene is amongst key genes in Shigella invasion, known as an antigen. PA20 protein of Bacillus anthracic can be separated from native PA protein during the infection and can be found in the serum of the infected patients and make it possible to diagnose the disease. CTxB, a known immune adjuvant, enhances the immunogenicity and is mainly used for the production of recombinant vaccines as a booster for immunization with antigen. In order to produce a vaccine with the immunogenic properties for the diseases, shigellosis and anthrax, different combinations of three ipaD, PA20 and CTxB genes were studied by bioinformatic tools in terms of their stability and similarity to the native proteins that are essential for their accurate performance. The aim of the present study was to introduce the best combination of the three antigens (ipaD, PA20 and CTxB) such that, when they are fused together, have a minimum effect on their structure and activity. Secondary and tertiary structures of proteins derived from different combinations of two or three proteins of ipaD, PA20 and CTxB were studied by MODELLER and PSIPRED software and the stability and lifespan of the fused genes were surveyed using ProtParam software. Analysis of data obtained from different combinations of ipaD, PA20 and CTxB genes by PSIPRED, ProtParam and MODELLER software showed that the best triple combination was PA20-CTxB-ipaD and the best of dual combinations was PA20-ipaD. When a protein combines with other proteins, the three-dimensional structure and physicochemical characteristics may dramatically change. According to the results of the present study, PA20 showed a strong stability, while ipaD showed a poor stability. Furthermore, all proteins in PA20- CTxB-ipaD combination had maintained their stability and this fusion can be used furthermore for vaccine design.