ORIGINAL ARTICLE   

Minerva Biotecnologica 2017 June;29(2):62-75

DOI: 10.23736/S1120-4826.16.01997-2

Copyright © 2015 EDIZIONI MINERVA MEDICA

language: English

Design and analysis of trivalent chimeric vaccine candidate against three enterotoxigenic bacteria: an in-silico approach

Rouhollah KAZEMI ¹, Jafar AMANI ², Asal AKHAVIAN ¹, Amir MOUSAVI ¹, Ali H. SALMANIAN ¹ ✉

¹ Department of Plant Bioproducts, Institute of Agricultural Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran; ² Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran

BACKGROUND: Diarrheal diseases caused by enteric bacteria remain as a leading cause of preventable death, especially among children under five years old in developing countries. In these cases, vaccines could be considered as an important solution for prevention of these diseases. The toxins of Vibrio cholerae (CT), Shiga-toxin-producing Escherichia coli (Stx) and enterotoxigenic E. coli (LT) are the most important virulent factors of these three enteric pathogens. In this study, we designed a trivalent recombinant immunogene from non-toxic part of these virulence factors consists of LtB (L), StxB (S) and CtxB (C). This chimeric protein (LSC) carrying important epitopes and the sequences with adjuvant potential activity, which could increase the possibility of eliciting effective immune responses.
METHODS: For successful heterologous expression of the LSC sequence, the genetic codes and a variety of critical parameters in the synthetic gene were optimized. Thermodynamic analyses for folding of mRNA structures revealed correct folding of the RNA representative good stability of this molecule. In-silico analysis was carried out to predict three- dimensional structure of this hypothetical protein and the model was validated using Ramachandran plot analysis.
RESULTS: High antigenicity of the construct was predicted by immunoinformatic analysis. Continuous and discontinuous B-cell epitopes were identified and showed the proper immunogenicity of this multimeric recombinant protein.
CONCLUSIONS: The results suggested that the protein deduced from this construct could act as a vaccine candidate against three important causative agents of diarrheal bacteria.

KEY WORDS: Vaccines - E. coli heat-labile enterotoxin - Shiga toxins - Cholera toxin - Computer simulation