Abstract
The ongoing severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic had brought disastrous consequences throughout the entire world. While several manufactured vaccines have been approved for emergency use, continuous efforts to generate novel vaccines are needed. In this study, we developed SARS-CoV-2 virus-like particles (VLPs) containing the full length of spike (S) glycoprotein (S full), S1, or S2 together with the influenza matrix protein 1 (M1) as a core protein. Successfully constructed VLPs expressing the S full, S1, and S2 via Sf9 cell transfections were confirmed and characterized by Western blot and transmission electron microscopy (TEM). VLP immunization in mice induced higher levels of spike protein-specific IgG and its subclasses compared to naïve control, with IgG2a being the most predominant subclass. S full and S1 immune sera elicited virus-neutralizing activities, but these were not strong enough to fully inhibit receptor–ligand binding of the SARS-CoV-2. Neutralizing activities were not observed from the S2 VLP immune sera. Overall, our findings revealed that S full or S1 containing VLPs can be developed into effective vaccines.
Highlights
While these viruses are frequently associated with zoonotic infections involving various avians and mammals, they are capable of infecting humans which can be lethal as demonstrated by the severe acute respiratory syndrome (SARS) outbreak of 2003 [1,2]
Original sequences of the full-length SARS-CoV-2 S glycoprotein, S1, and S2 domains were used for prediction (Figure 1A)
As the start codons were missing on the S2 domain, these were incorporated using the Transmembrane Protein Topology and Construct Schematic
Summary
Received: 10 May 2021Accepted: 12 August 2021Published: 18 August 2021Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, Switzerland.Attribution (CC BY) license (https://creativecommons.org/licenses/by/ 4.0/).Coronaviruses are single-stranded RNA viruses belonging to the order Nidovirales, family Coronaviridae, which can be subdivided into alphacoronavirus, betacoronavirus, and gammacoronavirus based on their antigenic and genetic characteristics [1]. While these viruses are frequently associated with zoonotic infections involving various avians and mammals, they are also capable of infecting humans which can be lethal as demonstrated by the severe acute respiratory syndrome (SARS) outbreak of 2003 [1,2]. In December of
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