1Department of Microbiology, NT.C., Islamic Azad University, Tehran, Iran.
2Department of Microbiology, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran.
3Department of Immunology, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran.
4Department of Medical Vaccine, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran.
چکیده
Introduction: Although considerable progress has been made in leptospiral vaccine development, their use is limited because of short-term and serovar-specific immunity. Thus far, many approaches have been used to identify heterologous and costeffective antigen(s) against leptospirosis. Recent advances have identified leptospiral immunoglobulin-like (Lig) proteins as promising candidates for vaccine development. Materials & Methods: Hence, in this study, the recombinant LigA subunit consists of the ligA9, ligA10, ligA11, and ligA12 domains, were selected as conserved regions of the LigA protein. Immunoinformatics approaches, including I-TASSER, ProSA, DiscoTope v2.0, and Molprobity were utilized to check the conformational accuracy. Furthermore, 10 of the most efficient peptides for MHC-I and II grooves were predicted by the ElliPro, NetMHCpan 4.1 EL and NetMHCIIpan 4.1 EL servers. Results: The Ramachandran plot showed acceptable conformations of the selected recombinant protein amino acid residues. The results showed that selected epitopes elicit both humoral- and cell-mediated immune responses. Hence, the selected epitopes were constructed in the pET41a+ plasmid and synthesized by General Biosystems. Recombinant plasmids were transferred to Escherichia coli Top10-DH5α and BL21 StarTM (DE3) competent cells for cloning and expression, respectively. Plasmid transformation and purification were confirmed using polymerase chain reaction (PCR) and enzymatic digestion. Recombinant LigA (r-LigA) was expressed in the presence of 0.5 M IPTG at 30˚C for 16 hours. The sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) result revealed the production of 38-kDa protein, which accumulated mostly in inclusion bodies and was purified using the urea method and dialysis. Dot blotting of the r-LigA protein confirmed a high degree of accuracy of immunogenicity. Conclusion: The present study revealed that r-LigA is a promising candidate for developing diagnostic and subunit leptospirosis vaccines.