Immune Netw.  2022 Oct;22(5):e41. 10.4110/in.2022.22.e41.

Application of Antimicrobial Peptide LL-37 as an Adjuvant for Middle East Respiratory Syndrome-Coronavirus Antigen Induces an Efficient Protective Immune Response Against Viral Infection After Intranasal Immunization

• Kim J
• Yang YL
• Jeong Y
• Jang YS

• KMID: 2536268
• DOI: http://doi.org/10.4110/in.2022.22.e41

Abstract

The human antimicrobial peptide LL-37 has chemotactic and modulatory activities in various immune cells, including dendritic cells. Because of its characteristics, LL-37 can be considered an adjuvant for vaccine development. In this study, we confirmed the possible adjuvant activity of LL-37 in mucosal vaccine development against Middle East respiratory syndrome-coronavirus (MERS-CoV) by means of intranasal immunization in C57BL/6 and human dipeptidyl peptidase 4 (hDPP4)-transgenic (hDPP4-Tg) mice. Intranasal immunization using the receptor-binding domain (RBD) of MERS-CoV spike protein (S-RBD) recombined with LL-37 (S-RBD-LL-37) induced an efficient mucosal IgA and systemic IgG response with virus-neutralizing activity, compared with S-RBD. Ag-specific CTL stimulation was also efficiently induced in the lungs of mice that had been intranasally immunized with S-RBDLL-37, compared with S-RBD. Importantly, intranasal immunization of hDPP4-Tg mice with S-RBD-LL-37 led to reduced immune cell infiltration into the lungs after infection with MERSCoV. Finally, intranasal immunization of hDPP4-Tg mice with S-RBD-LL-37 led to enhanced protective efficacy, with increased survival and reduced body weight loss after challenge infection with MERS-CoV. Collectively, these results suggest that S-RBD-LL-37 is an effective intranasal vaccine candidate molecule against MERS-CoV infection.

Keyword

Antigen; Antimicrobial peptide; Infection; MERS-CoV; Vaccine