Preparation and Purification of Porcine Circovirus Type 2 Chimeric
Virus-Like Particles by a New Affinity Purification System
Abstract
Porcine epidemic diarrhea virus (PEDV) causes severe watery diarrhea
with dehydration and high mortality in pigs, bringing huge economic
losses to the swine industry worldwide. The current prevention of PEDV
is mainly concentrated on inactivated vaccines. In this study, two novel
B cell epitopes S1D5 (residues 744-759) and S1D6 (residues 756-771) of
PEDV were displayed on capsid (Cap) protein of porcine circovirus type 2
(PCV2) in Escherichia coli (E. coli) expression system. The recombinant
protein Cap-S1D can self-assemble into chimeric virus-like particles
(VLPs), which were similar in size and morphology to native PCV2
particles. In addition, an effective affinity purification system for
the purification of chimeric VLPs, referred to Gram-positive Enhancer
Matrix-protein anchor domain-variable domain of heavy chain of
heavy-chain antibody 8 (GEM-PA-VHH8), was screened and identified. The
PA-VHH8 fusion protein can specifically bind to GEM particles by
covalent bond adsorption, which contributes to display Cap-S1D chimeric
VLPs on the surface of GEM particles. Cap-S1D chimeric VLPs were
successfully purified with the developed purification system and the
purification efficiency was close to 90%. What’s more, the purified
chimeric VLPs homemade vaccine induced a stronger humoral and cellular
immune responses compared to the unpurified recombinant protein in pigs.
Thus, the GEM-PA-VHH system provided an effective and safe technology
for the preparation and purification of chimeric VLPs to prevent PEDV
and PCV2 infection.