Flagellin Improves the Immune Response of an Infectious Bursal Disease Virus (IBDV) Subunit Vaccine

• Published in: Vaccines
• Main Authors: Asad Murtaza, Haroon Afzal, Thu-Dung Doan, Guan-Ming Ke, Li-Ting Cheng
• Format: Article
• Language: English
• Published: MDPI AG 2022-10-01
• Subjects: infectious bursal disease virus; immunosuppression; flagellin; adjuvant; N-terminus; chimeric protein
• Online Access: https://www.mdpi.com/2076-393X/10/11/1780

Flagellin activates the immune system through Toll-like receptor 5 (TLR5) and can work as an adjuvant for subunit vaccines. In this study, we tested the adjuvancy of two different N-terminal fragments of flagellin, (1) FliC₉₉, residues 1–99, and (2) FliC₁₇₆, residues 1–176, to incorporate larger areas of the hotspot region for potentially higher levels of TLR5 activation and immune response. A truncated version of the VP2 protein (name <i>t</i>VP2, residues 199–356) of the Infectious bursal disease virus (IBDV) was genetically linked to the flagellin constructs, and the immune response was evaluated in chickens. Results showed that both chimeric antigen–adjuvant constructs increased humoral (total IgG titers), cellular and cytokine immune response (IL-4, IFN-γ). The resulting antibody also successfully neutralized IBDV. We conclude that the N-terminus of flagellin can act as an immune activator to enhance vaccine efficacy.