Plant-Derived Trimeric CO-26K-Equivalent Epitope Induced Neutralizing Antibodies Against Porcine Epidemic Diarrhea Virus
Thuong Thi Ho, Nguyễn Thu Giang, Ngoc Bich Pham, Van Phan Le, Thi Bich Ngoc Trinh, Trang Huyen Vu, Hoang Trong Phan, Udo Conrad, Chu Hoàng Hà
Abstract
Porcine epidemic diarrhoea 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.