Recombinant chicken interleukin-7 as a potent adjuvant increases the immunogenicity and protection of inactivated infectious bursal disease vaccine

Dan Cui,Jianlou Zhang,Yuzhu Zuo,Liyue Wang,Shanshan Huo,Fei Zhong,Yonghong Zhang,Xiujin Li

doi:10.1186/s13567-017-0497-3

Dan Cui, Jianlou Zhang + Show 6 more

Open Access

https://doi.org/10.1186/s13567-017-0497-3

Copy DOI

Abstract

Our previous work showed that a plasmid-based chicken interleukin-7 (chIL-7) gene expression vector possessed potent adjuvant activity for a VP2 DNA vaccine against chicken infectious bursal disease virus (IBDV). Whether recombinant chIL-7 prepared in procaryotic expression system has the adjuvant activity for inactivated IBDV vaccine remains unknown. Here, we prepared recombinant chIL-7 using an E. coli expression system and analyzed its adjuvant activity for the inactivated IBDV vaccine. The results show that the recombinant chIL-7 was successfully prepared in E. coli using the pET20b vector, which possessed biological activity to stimulate mouse B lymphocyte proliferation. Co-administration of the chIL-7 with inactivated IBDV vaccine significantly increased specific serum antibody titers against IBDV, enhanced lymphocyte proliferation and IFN-γ and IL-4 productions, and increased protection against virulent IBDV infection.

Highlights

Infectious bursal disease (IBD), an acute and highly contagious chicken disease, is caused by infection with IBD virus (IBDV) and characterized by virus-induced immunosuppression in young chickens mainly via destruction of antibody-producing B cells in the bursa of Fabricius [1, 2]
The results show that the signal peptide-free chicken interleukin-7 (chIL-7) gene was fused with the prokaryotic signal peptide at its 5′-terminus, and His-tag at its 3′-terminus (Figure 1D)
Secretory expression in E. coli and biological identification of recombinant chIL‐7 To confirm whether the constructed vector can mediate chIL-7 expression in a secretory manner in E. coli and whether large-scale preparation of recombinant chIL-7 can be achieved, BL21 E. coli was transformed with pET20b-chIL-7/H plasmid

Summary

Introduction

Infectious bursal disease (IBD), an acute and highly contagious chicken disease, is caused by infection with IBD virus (IBDV) and characterized by virus-induced immunosuppression in young chickens mainly via destruction of antibody-producing B cells in the bursa of Fabricius [1, 2]. The virus replicates rapidly in developing B cells causing the destruction of the precursors of antibody-producing B cells in the bursa, resulting in immunosuppression leading to vaccination failure and susceptibility to other microbial infections [3]. IBD has not been completely controlled vaccination programs have been extensively implemented worldwide using live attenuated or inactivated IBDV vaccines. The live IBDV vaccine has often caused chicken immunosuppression and sub-clinical infection [7], whereas the inactivated IBDV vaccine has not completely protected chickens from virulent IBDV attack [8]. Development of potent adjuvants may be required to enhance the immunogenicity of inactivated IBDV vaccines

Methods

Results

Conclusion