Document Type : Original Articles
Authors
1
Poultry Immunology, Department of Poultry Science, Faculty of Animal Sciences, Tarbiat Modares University, Tehran, Iran
2
Department of Microbiology, Shi.C., Islamic Azad University, Shiraz, Iran
3
Department of Biology, Zarg.C., Islamic Azad University, Zarghan, Iran
4
Department of Poultry Vaccine Research and Production, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension organization, Karaj 3197619751, Iran
5
Department of Research and Production of Poultry Viral Vaccine, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization, Karaj 3197619751, Iran
10.66224/ari.2026.370871.3877
Abstract
Introduction: Infectious bronchitis virus (IBV) affects chickens with significant economic losses in the poultry industry. The spike (S) glycoprotein of IBV is an appropriate immunogen for vaccine design. However, its glycosylation and diversity remain to be addressed to design a broadly protective antigen expressed in bacterial hosts. This study employed an in silico approach to nominate conserved B-cell epitopes within the S protein as potential targets which could be expressed in E. coli hosts. Material and Methods: The IBV S protein sequence was retrieved and characterized. Linear B-cell epitopes, N-glycosylation sites, physicochemical properties (flexibility, beta-turn propensity, surface accessibility, and hydrophilicity), and conservation of the sequence were analyzed. Results: Less than 30 linear epitopes with a length of > 4 aa were predicted. About 28 residues undergo glycosylation. Beta turns were abundant at the N-terminus of the S sequence. The most flexible and surface accessible residues were G405 and R1157 respectively. The longest hydrophilic region was 1021-1052 residues. The BLAST results showed 100 hits with lengths of 478-1181 amino acids, query coverage of 46%-100% and identity of 62.86%-100%. Six versions of multi-epitope constructs were designed. Conserved B-cell epitopes with favorable physicochemical properties and no N-glycosylation sites were selected. The YGPLQGGCKQSVFK was found to be the most prevalent (89% of sequences) epitope. The first and second constructs were 80-residue and 160-residue NON-IMMUNOGENs, respectively. The third, fourth, fifth and sixth constructs were 216-residue, 228-residue, and 356-residue IMMUNOGENs, respectively. Conclusion: Fourth and sixth constructs were nominated as the best broad-spectrum antigens concerning immune responses.
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