Background: Virus-like Particles (VLPs) are non-genetic multimeric nanoparticles synthesized
through in vitro or in vivo self-assembly of one or more viral structural proteins. Immunogenicity
and safety of VLPs make them ideal candidates for vaccine development and efficient
nanocarriers for foreign antigens or adjuvants to activate the immune system.
Aims: The present study aimed to design and synthesize a chimeric VLP vaccine of the phage Qbeta
(Qβ) coat protein presenting the universal epitope of the coronavirus.
Methods: The RNA phage Qβ coat protein was designed and synthesized, denoted as Qbeta. The
CoV epitope, a universal epitope of coronavirus, was inserted into the C-terminal of Qbeta using
genetic recombination, designated as Qbeta-CoV. The N-terminal of Qbeta-CoV was successively
inserted into the TEV restriction site using mCherry red fluorescent label and modified affinity purified
histidine label 6xHE, which was denoted as HE-Qbeta-CoV. Isopropyl β-D-1-thiogalactopyranoside
(IPTG) assessment revealed the expression of Qbeta, Qbeta-CoV, and HE-Qbeta-CoV in
the BL21 (DE3) cells. The fusion protein was purified by salting out using ammonium sulfate and
affinity chromatography. The morphology of particles was observed using electron microscopy.
The female BALB/C mice were immunized intraperitoneally with the Qbeta-CoV and HE-Qbeta--
CoV chimeric VLPs vaccines and their sera were collected for the detection of antibody level and
antibody titer using ELISA. The serum is used for the neutralization test of the three viruses of
MHV, PEDV, and PDCoV.
Results: The results revealed that the fusion proteins Qbeta, Qbeta-CoV, and HE-Qbeta-CoV could
all obtain successful expression. Particles with high purity were obtained after purification; the
chimeric particles of Qbeta-CoV and HE-Qbeta-CoV were found to be similar to Qbeta particles in
morphology and formed chimeric VLPs. In addition, two chimeric VLP vaccines induced specific
antibody responses in mice and the antibodies showed certain neutralizing activity.
Conclusion: The successful construction of the chimeric VLPs of the phage Qβ coat protein presenting
the universal epitope of coronavirus provides a vaccine form with potential clinical applications
for the treatment of coronavirus disease.