Vaccines that incorporate multiple SARS-CoV-2 antigens can further broaden the breadth of virus-specific cellular and humoral immunity. This study describes the development and immunogenicity of SARS-CoV-2 VLP vaccine that incorporates the four structural proteins of SARS-CoV-2.

Methods

VLPs were generated in transiently transfected HEK293 cells, purified by multimodal chromatography, and characterized by tunable-resistive pulse sensing, AFM, SEM, and TEM. Immunoblotting studies verified the protein identities of VLPs. Cellular and humoral immune responses of immunized animals demonstrated the immune potency of the formulated VLP vaccine.

Results

Transiently transfected HEK293 cells reproducibly generated vesicular VLPs that were similar in size to and expressing all four structural proteins of SARS-CoV-2. Alum adsorbed, K3-CpG ODN-adjuvanted VLPs elicited high titer anti-S, anti-RBD, anti-N IgG, triggered multifunctional Th1-biased T-cell responses, reduced virus load, and prevented lung pathology upon live virus challenge in vaccinated animals.

Conclusion

These data suggest that VLPs expressing all four structural protein antigens of SARS-CoV-2 are immunogenic and can protect animals from developing COVID-19 infection following vaccination.

Graphical Abstract

SARS-CoV-2 VLP vaccine that incorporates the four structural proteins of SARS-CoV-2 is reproducibly produced in suspension adapted HEK293 cells. Alum adsorbed, K3-CpG ODN-adjuvanted VLPs elicit high titer anti-S, anti-RBD, anti-N IgG, and neutralizing antibodies in mice, rats, and ferrets. The VLP vaccine supports multifunctional Th1-biased T-cell responses and demonstrate immunoprotective activity against live SARS-CoV-2 challenge in vaccinated mice. Abbreviations: Alum, aluminum hydroxide; CpG, cytosine-phosphate-guanosine dinucleotide; HEK293, human embryonic kidney cell line; ODN, oligodeoxynucleotide; RBD, receptor binding domain; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; Th, T-helper cell; VLP, virus-like particle.

CONFLICT OF INTEREST

There is no financial conflict of interest to declare by the Authors.

Supporting Information

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Citing Literature

Volume77, Issue1

January 2022

Pages 258-270