Plant-Derived Trimeric CO-26K-Equivalent Epitope Induced Neutralizing Antibodies Against Porcine Epidemic Diarrhea Virus.

Thuong Thi Ho,Udo Conrad,Ha Hoang Chu,Ngoc Bich Pham,Trang Huyen Vu,Hoang Trong Phan,Van Phan Le,Thi Bich Ngoc Trinh,Giang Thu Nguyen

doi:10.3389/fimmu.2020.02152

Abstract

Porcine epidemic diarrhea virus (PEDV) is a causative agent of a highly infectious disease with a high mortality rate, especially in newborn piglets in Asian countries resulting in serious economic loss. The development of a rapid, safe, effective and cost-efficient vaccine is crucial to protect pigs against PEDV infection. The COE antigen is regarded to be a major target for subunit vaccine development against PEDV infection. The naturally assembled COE protein forms a homotrimeric structure. In the present study, we successfully produced a trimeric COE protein as a native structure by fusion with the C-terminal isoleucine zipper trimerization (GCN4pII) motif in Nicotiana benthamiana, with a high expression level shown via semi-quantified Western blots. Trimeric COE protein was purified via immobilized metal affinity chromatography (IMAC), and its trimeric structure was successfully demonstrated by a cross-linking reaction, and a native PAGE gel. A crude extract containing the COE trimer was used for evaluating immunogenicity in mice. After 1 and 2 booster immunizations, the crude extract containing trimeric COE elicited elevated PEDV-specific humoral responses, as demonstrated by ELISA and Western blot analyses. Notably, a virus-neutralizing antibody assay indicated that the neutralization activities of sera of mice vaccinated with the crude extract containing COE-GCN4pII were similar to those of mice vaccinated with a commercial vaccine. These results suggest that crude extract containing trimeric COE is a promising plant-based subunit vaccine candidate for PEDV prevention.

Highlights

Porcine epidemic diarrhea (PED) is a highly infectious disease identified by dehydration, acute watery diarrhea, and a high mortality rate, especially in newborn piglets [1,2,3]
The immunogenicity in mice group G3 vaccinated with the COE trimer in crude extract was compared to those of mice positive control group G2 vaccinated with commercial Porcine epidemic diarrhea virus (PEDV) vaccine and mice negative control group G1 vaccinated with crude extracts from non-transgenic plants
Western blot results demonstrated that PEDVspecific IgG antibodies were presented in mice group G3 and mice group G2 after the second and the third immunization

Summary

Introduction

Porcine epidemic diarrhea (PED) is a highly infectious disease identified by dehydration, acute watery diarrhea, and a high mortality rate, especially in newborn piglets [1,2,3]. PEDV, the disease causative agent of PED, spreads to several countries in the world, and resulting in serious economic loss to the swineproduction [4,5,6]. The S protein is a target for neutralizing antibody induction because it harbors virusneutralizing epitopes and is the principle antigenic determinant [8]. The S protein is naturally assembled in homotrimeric form with a number of predicted glycosylation sites [12]

Methods

Results

Conclusion