Computational Design of Serotype Independent Vaccine against Streptococcus pneumoniae Based on B-Cell Epitopes of Pneumococcal Plasmid Stabilization Protein

Shirin Tarahomjoo^1,

¹Division of Genomics and Genetic Engineering, Department of Biotechnology and Central Laboratory, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj 31975/148, Iran

Cite this paper

Shirin Tarahomjoo. Computational Design of Serotype Independent Vaccine against Streptococcus pneumoniae Based on B-Cell Epitopes of Pneumococcal Plasmid Stabilization Protein. American Journal of Medical and Biological Research. 2016; 4(5):90-94. doi: 10.12691/AJMBR-4-5-2

Abstract

Pneumococcal conjugate vaccines (PCVs) were constructed through chemical conjugation of pneumococcal capsules to immunogenic carrier proteins. The PCVs implementation in developing countries was prevented by their high manufacturing costs. This issue can be overcome by development of protein based vaccines against pneumococci. Antibody responses are necessary for protection against S. pneumoniae. The plasmid stabilization protein (PSP) was already identified as a pneumococcal surface protein able to elicit protection against S. pneumoniae serotype 19F and its protective B-cell epitope regions were determined. Whole antigens are not as potent as epitope based vaccines and every epitope in a multi epitope based vaccine can individually induce a protective immune response against the pathogen. Thus better immunoprotection can be achieved by multi epitope based vaccines. In the present study, therefore, we aim to design a multi epitope vaccine against pneumococci based on the identified B-cell epitope regions of PSP using immunoinformatic tools. These regions were joined together using the (EAAAK) ₄ linker. The resulting antigen (HPBE) showed much higher immunoprotective ability compared to PSP regarding the VaxiJen scores. The codon optimization was done for HPBE using OPTIMIZER. Analysis of the mRNA secondary structure using Mfold tool revealed no stable hairpin at the 5' end and thus the antigen can be expressed appropriately. The 3D model of the antigen resulted from I-TASSER indicated the presence of alpha helix, beta sheet, turn, coil, and 3₁₀ helix as the protein structural elements. Analyzing physicochemical properties of the antigen using ProtParam showed that it was stable and its half life in Escherichia coli was more than 10 h. Considering the GRAVY score, HPBE possessed a hydrophilic nature and it can be expressed in the soluble form in E. coli at 79.6% probability. Our results demonstrated that HPBE is a suitable vaccine candidate, which can elicit protection against common S. pneumoniae serotypes causing invasive pneumococcal disease in children less than 5 years of age.

Keywords

computational design, pneumococcal conjugate vaccines, protective epitope, protein based vaccines, Streptococcus pneumoniae

Copyright

This work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

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