Superior adjuvanticity of the genetically fused D1 domain of Neisseria meningitides Ag473 lipoprotein among three Toll-like receptor ligands.

Huipeng Lu,Yajie Wang,Yang Zong,Xiaokai Zhang,Xiaoli Xia,Yuyang Wang,Xinyu Zhang,Huaichang Sun

doi:10.1042/bsr20193675

Huipeng Lu, Yajie Wang + Show 6 more

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https://doi.org/10.1042/bsr20193675

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Abstract

Toll-like receptor (TLR) ligands have emerged as the attractive adjuvant for subunit vaccines. However, selection of TLR ligands needs to be rationally chosen on the basis of antigen and adjuvant properties. In the present study, we expressed the Ag473 lipoprotein from Neisseria meningitides, flagellin FlaB from Vibrio vulnificus and heat shock protein 70 from Mycobacterium tuberculosis (mHsp70) in Escherichia coli as single proteins and fusion proteins with VP2 protein of infectious bursal disease virus (IBDV). Both cellular and humoral adjuvanticities of the three TLR ligands were compared by immunization of mice in two different ways. Among the three co-administered TLR ligands, recombinant Ag473 lipoprotein exhibited the highest cellular and humoral adjuvanticities, including promotion of IL-4, IL-12, IFN-γ and IBDV VP2-specific antibody production. Among the three genetically fused TLR ligands, fusion with Ag473 D1 domain exhibited the highest cellular and humoral adjuvanticities. Overall, the adjuvanticities of genetically fused TRL ligands were significantly higher than that of co-administered TLR ligands. Fusion with Ag473 D1 domain exhibited superior adjuvanticity among the three TLR ligands delivered in two different ways.

Highlights

Recombinant protein- or synthetic peptide-based subunit vaccines have a better safety profile than traditional inactivated and live attenuated vaccines
To compare the adjuvanticities of three Toll-like receptor (TLR) ligands delivered in two different ways, the synthetic sequences for the capsid protein of infectious bursal disease virus (IBDV) (VP2) protein of IBDV, C-terminal segment of heat shock protein 70 of Mycobacterium tuberculosis (mHsp70), lipoprotein of Neisseria meningitides (Ag473) lipoprotein or its D1 domain of Ag473 (D1) domain of N. meningitides, and flagellin flagellin B (FlaB) of V. vulnificus were cloned individually or as VP2 fusion genes into pET-30 vector
Both recombinant Ag473 and D1-VP2 fusion proteins were expressed efficiently in BL21 (DE3), which may be contributed to adaption of the coding sequence for E. coli codon usage

Summary

Introduction

Recombinant protein- or synthetic peptide-based subunit vaccines have a better safety profile than traditional inactivated and live attenuated vaccines. Alum salts and oil-in-water emulsions are still commonly used in licensed vaccines due to their good safety record, these traditional adjuvants cannot stimulate appropriate cellular immune response that is important for antiviral infections [2]. Cytokine production and/or the maturation of professional antigen-presenting cells (APC), TLR ligands can stimulate both innate and adaptive immune responses [4]. Intranasal immunization of mice with FlaB flagellin and the P domain of VP1 protein from Norovirus can induce a potent antibody and cellular immune responses in both systemic and mucosal compartments [9]. We compared the adjuvanticities of three different TLR ligands delivered in two different ways using the recombinant VP2 protein of infectious bursal disease virus (IBDV) as the model antigen in a mouse model

Materials and methods

Results and discussion

Conclusion