Trigger factor assisted self-assembly of canine parvovirus VP2 protein into virus-like particles in Escherichia coli with high immunogenicity

Liangliang Nan,Hua Feng,Gaiping Zhang,Yafei Li,Yunchao Liu,Yinglei Cui,Juan Wang,Enmin Zhou,Yanwei Wang,Dongmin Liu,Pengchao Ji,Chen Chen

doi:10.1186/s12985-018-1013-8

Abstract

Canine parvovirus (CPV) has been considered to be an important pathogen, which can cause acute infectious disease in canids. Although current vaccines are effective in preventing CPV infection, safety problems still remain unsolved. In this study, a subunit vaccine against CPV based on virus-like particles (VLPs) with good safety and immunogenicity is reported. Soluble CPV VP2 protein was produced by co-expression of chaperone trigger factor (Tf16) in Escherichia coli (E.coli), and assembled into CPV VLPs which could be affected by NaCl and pH. At 250 mM NaCl pH 8.0, the VLPs co-expressed with Tf16 had similar size (25 nm) and shape with the authentic virus capsid under the transmission electron microscopy (TEM), which is also in accordance with the dynamic light scattering (DLS) data. Immunization with these particles could induce high-titer hemagglutination inhibition (1:12288) and neutralizing antibodies (1:6144) in guinea pigs. Splenic cells of them could secrete IFN-γ and IL-4 after stimulation by CPV. Thus, the VLPs produced by the new approach with high yield and immunogenicity could be a potential candidate for CPV vaccine.

Highlights

Canine Parvovirus (CPV) disease is a highly contagious infectious disease caused by canine parvovirus, which is manifested as severe hemorrhagic enteritis in dogs of all ages and myocarditis in puppies [1]
Cells and virus Feline kidney F81 cells were cultured in Dulbecco’s modified Eagle’s medium (DMEM; Hyclone), which was supplemented with 100 U/ml of penicillin, 100 mg/ml of streptomycin and 10% fetal bovine serum (FBS; Gibco) at 37 °C in a 5% CO2 incubator
The virus-like particles (VLPs) and commercial vaccine groups showed significantly higher (p < 0.01) IL-4 production compared to the control group (Fig. 4b)

Summary

Introduction

Canine Parvovirus (CPV) disease is a highly contagious infectious disease caused by canine parvovirus, which is manifested as severe hemorrhagic enteritis in dogs of all ages and myocarditis in puppies [1]. Since it was first discovered in 1978, domestic dogs and some wild animals have been facing a huge risk because of the high morbidity and mortality throughout the world [2]. CPV belongs to genus Protoparvovirus within family Parvoviridae and has the ability to agglutinate pig erythrocytes [3] It is a 25 nm diameter particle consisting of three structural proteins, VP1, VP2 and VP3. CPV-2a contained 5 amino acid substitutions (M87L, I101T, A300G, D305Y, and V555I) and is the predominant variant in Asia; CPV-2b had a single additional substitution (N426D) and an I555V reversion; CPV-2c featuring N426E and S297A is the predominant variant in Europe and Latin America [6,7,8]

Methods

Results

Conclusion