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. 2023 May;18(7):403-410.
doi: 10.2217/fvl-2022-0172. Epub 2023 Jun 1.

CpG 684: an effective adjuvant for the inactivated COVID-19 vaccine in mice

Jiandong Liu  1 , Tianle Cang  1 , Congli Jiang  2 , Kelei Li  1 , Siyuan Liu  1 , Haixin Wang  1 , Meirong Wang  1 , Yan Chen  3 , Yan Shao  3 , Jiankai Liu  1
Affiliations

CpG 684: an effective adjuvant for the inactivated COVID-19 vaccine in mice

Jiandong Liu et al. Future Virol. 2023 May.

Abstract

Aim: This study used CpG 684 as adjuvant of inactivated COVID-19 vaccine to detect a humoral and cellular immune response in mice.

Materials & methods: We used 10 and 20 µg CpG 684 as adjuvants of an inactivated COVID-19 vaccine to immunize mice. IgG, IgG1, IgG2a, IgG2b and IgM binding antibodies were detected in serum by ELISA. The IFN-γ cytokine was detected by ELISPOT.

Results: CpG 684 improved spike-specific IgG and IgM subtype binding antibodies and increased the neutralizing antibody titer against prototype, Delta and Beta strains. CpG 684 also improved cellular immune response.

Conclusion: CpG 684 is an effective adjuvant for inactivated COVID-19 vaccine.

Keywords: CpG; SARS-COV-2; neutralizing antibody; vaccine; variants.

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Conflict of interest statement

Conflicts of interest disclosure The authors declare that there are no conflicts of interest present.

Figures

Figure 1.
Figure 1.. Mouse immunity and gE protein-specific IgG binding antibodies.
(A) Immunization experiment. (B) Spike-specific IgG binding antibody responses.
Figure 2.
Figure 2.. Spike-specific IgG subclass binding antibody responses.
(A) IgG1 binding antibody responses. (B) IgG2a binding antibody responses. (C) IgG2a/IgG1 ratio. (D) IgG2b binding antibody responses. *p < 0.05.
Figure 3.
Figure 3.. Spike-specific IgM binding antibody responses.
*p < 0.05.
Figure 4.
Figure 4.. The neutralizing antibody titer of mice sera against prototype, Delta and Beta strains of SARS-COV-2.
(A) The neutralizing antibody titer against prototype strain. (B) The neutralizing antibody titer against the Delta strain. (C) The neutralizing antibody titer against the Beta strain. **p < 0.01.
Figure 5.
Figure 5.. ELISPOT spots forming unit of IFN-γ.
*p < 0.05; ***p < 0.001.
See this image and copyright information in PMC

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