Effect of Different Adjuvants on Immune Responses Elicited by Protein-Based Subunit Vaccines against SARS-CoV-2 and Its Delta Variant

Viruses. 2022 Feb 28;14(3):501. doi: 10.3390/v14030501.

Abstract

The global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become more serious because of the continuous emergence of variants of concern (VOC), thus calling for the development of broad-spectrum vaccines with greater efficacy. Adjuvants play important roles in enhancing the immunogenicity of protein-based subunit vaccines. In this study, we compared the effect of three adjuvants, including aluminum, nanoparticle manganese and MF59, on the immunogenicity of three protein-based COVID-19 vaccine candidates, including RBD-Fc, RBD and S-trimer. We found that the nanoparticle manganese adjuvant elicited the highest titers of SARS-CoV-2 RBD-specific IgG, IgG1 and IgG2a, as well as neutralizing antibodies against infection by pseudotyped SARS-CoV-2 and its Delta variant. What is more, the nanoparticle manganese adjuvant effectively reduced the viral load of the authentic SARS-CoV-2 and Delta variant in the cell culture supernatants. These results suggest that nanoparticle manganese, known to facilitate cGAS-STING activation, is an optimal adjuvant for protein-based COVID-19 subunit vaccines.

Keywords: COVID-19; MF59; SARS-CoV-2; aluminum; nanoparticle manganese; subunit vaccines; variants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COVID-19 Vaccines
  • COVID-19* / prevention & control
  • Humans
  • Immunity
  • Mice
  • Mice, Inbred BALB C
  • SARS-CoV-2
  • Vaccines, Subunit
  • Viral Vaccines*

Substances

  • COVID-19 Vaccines
  • Vaccines, Subunit
  • Viral Vaccines

Supplementary concepts

  • SARS-CoV-2 variants