Background and Objective: Newcastle disease (ND) is a highly contagious viral infection that mainly affects birds, especially domestic fowl. The disease is caused by a member of the well-known avian paramyxovirus type 1, also called NDV. Due to the lack of effective treatment for this disease, current strategies for poultry vaccination are mainly based on the hemagglutinin neuraminidase (HN) gene, which encodes a multifunctional protein. It plays an important role in virus binding, entry, and pathogenesis. The HN protein is considered a potent target for peptide vaccines, an innovative approach to enhance immunity against a wide range of viral challenges, including NDV. Methods: In this study, we investigated the peptide backbone of the Newcastle vaccine, regarding the HN protein. Uniprot database, was used to investigate the HN homologues of Newcastle virus, whose crystallography results were reported. Multiple alignment was performed in the CLC Main Workbench program. Protein 3D structure was predicted by PHYRE2 and compered with its altered structures in Chimera X. Results: Fifteen homologues of HN were found in Uniprot. Multiple alignments suggested that the consensus sequence was identical throughout its sequence for the 15 Newcastle strains, with just two amino acid substitution at positions 62 (A/R) and 329 (A/V), resulting in final four sequences, all of which were submitted for 3D Structure prediction. Position 62 is omitted in mature protein, so it was not included in the modeling. According to PHYE2, the closest model for NDV-HN was 4fzh with 78% coverage and 100% confidence. The amino acid variation did not lead to any modification in the protein structure, so that both of mentioned residues were contributed in a B-turn region of the protein. Conclusion: Peptide-based vaccines offer a range of advantages for combating Newcastle disease. The results of this study suggest that the HN gene is a highly conserved protein among Newcastle virus strains. Thus it could be considered as a strong antigen against various types of NDV.
