Abstract
Background:
Infectious bronchitis is an acute and highly transmissible respiratory illness that causes substantial economic losses in poultry farming. Vaccination remains the primary control strategy; however, frequent mutations in the key structural protein of the virus, specifically the spike glycoprotein, reduce the effectiveness of vaccines.

Aim:
In this study, we used reverse vaccinology and molecular modeling approaches to design a safe and effective vaccine against infectious bronchitis in chickens.

Methods:
Infectious bronchitis virus-like protein was selected as the antigen target. Five multiepitope cytotoxic T cell epitopes, 6 helper T cell epitopes, and 4 linear epitopes were selected from the S1 and S2 protein sequences. The nonstructural protein sequence (nsp1-nsp4) from the Venezuelan equine encephalitis virus as a copy machinery system and the cholera toxin B subunit as a build-in adjuvant were added to the proposed vaccine.

Results:
Based on immunoinformatic analysis, the designed vaccine is predicted to be antigenic (antigenic score of 0.827), non-allergic, nontoxic, and stable with basic PI (9.78). The proposed model exhibits good structural integrity and a favorable binding profile. Analysis of the Ramachandran plot showed that 72% of the amino acids were located in the favored area, which is a strong indicator of a stable protein fold. A Z-score of −10.6 further validates the model’s overall geometry’s high quality. Furthermore, molecular docking showed that the proposed protein has affinity for TLR3 binding in chickens.

Conclusion:
Our results indicate that the proposed vaccine is a potentially effective solution for chickens with infectious bronchitis. However, additional laboratory studies are required to verify its efficacy and safety.

Key words: Infectious bronchitis, self-amplifying mRNA, multiepitope vaccine and Immunoinformatic approaches