Table 1 RBD-based vaccines with different formulations and the type of immune response that they trigger
Vaccine name | Developer | Dose timing | Clinical trials | Vaccine type | Used adjuvant | Immune response mechanism | Th1/Th2 immune balance | Reference |
|---|---|---|---|---|---|---|---|---|
ArCov | Chinese Academy of Military Medical Sciences | 0 and 28 days (100 μg) | Phase 1 clinical trial (ChiCTR2000034112) | mRNA encodes the SARS-CoV-2 RBD | Lipid nanoparticle encapsulated mRNA (mRNA-LNP) | Increase the level of CD4+ and CD8+ effector memory T, IFN-γ, TNF-α, and IL-2 in isolated splenocytes | Induce Th1 cellular immune response | [32] |
BNT162b1 | BioNTech and Pfizers | 0 and 28 days (1–50 μg) | Phase 1 and 2 clinical trial | mRNA encodes the SARS-CoV-2 RBD | Lipid nanoparticle encapsulated mRNA (mRNA-LNP) | Elevation of CD4+ and CD8+ T cell responses and increase in the secretion of IFN-γ, IL-2, and IL-12p70 | Induce Th1 cellular immune response | [33] |
Folded RBD-PreS fusion vaccine | - | Three times in 3 weeks (20 or 40 μg) | - | SARS-CoV-2 RBD fused to the N- and C-terminus of hepatitis B virus (HBV) surface antigen PreS expressed in E. coli expression system | Aluminum hydroxide | Induce production of allergen-specific IgG responses (IgG1 and IgG 4) | - | [34] |
ZF2001 | Institute of Microbiology, Chinese Academy of Sciences, and Anhui Zhifei Longcom Biopharmaceutical | 0, 30, and 60 days (25 μg per dose) | Phase 3 clinical trial | Adjuvant-based protein subunit vaccine | Aluminum hydroxide | Elevation of the levels of MHC class II-related genes, including cd74 and H2-Aa and induced the presentation of antigens to CD4+ T cells via MHCII molecules | Increase TH1 cytokine production (IFN-γ, IL-2) and TH2 cytokine production (IL-4) cytokine production resulting in Th1/Th2 balanced cytokines | |
A yeast-expressed RBD-based SARS-CoV-2 vaccine | - | 0, 4, and 9 weeks | - | Yeast expression system | 3M-052-aluminum | Increase nAbs & elevation of CD4+ and CD8+ T cell responses | Induce Th1-biased CD4+ T cell reactions | [37] |
Unnamed recombinA2:I8accine | West China Hospital | 0, 21 days and 0, 14, 28 days | Phase 2 clinical trial | The baculovirus expression system | Aluminum hydroxide gel | Increased levels of IgM and IgG in sera and increased the levels of IFN-γ and IL-4 from isolated lymphocytes | Enhanced and TH1/TH2 balanced cytokine production | [38] |
Mutant RBD vaccines | - | 0 and 14 days | - | HIV-1 backbone | Aluminum | High geometric mean titers (GMTs) of neutralizing antibodies (nAbs) | - | [39] |