The Immunogenicity of CpG, MF59-like, and Alum Adjuvant Delta Strain Inactivated SARS-CoV-2 Vaccines in Mice

• Published in: Vaccines (Basel) 2024-01, Vol.12 (1), p.60
• Main Authors: Xu, Kangwei, Li, Jing, Lu, Xu, Ge, Xiaoqin, Wang, Kaiqin, Wang, Jiahao, Qiao, Zhizhong, Quan, Yaru, Li, Changgui
• Format: Article
• Language: English
• Subjects: ACE inhibitors; Adjuvants; Aluminum; Analysis; Antibodies; Antigens; Bias; CD4 antigen; Cell culture; COVID-19; COVID-19 vaccines; Deactivation; Delta; Flow cytometry; Health aspects; Immune response; Immunity; Immunization; Immunogenicity; Immunoglobulin G; inactivated vaccines; Lymphocytes; Lymphocytes T; Neutralization; Pandemics; Proteins; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Vaccines; Viral diseases; Viruses
• ISSN: 2076-393X; 2076-393X
• DOI: 10.3390/vaccines12010060

The continuous evolution and mutation of SARS-CoV-2 have highlighted the need for more effective vaccines. In this study, CpG, MF59-like, and Alum adjuvant Delta strain inactivated SARS-CoV-2 vaccines were prepared, and the immunogenicity of these vaccines in mice was evaluated. The Delta + MF59-like vaccine group produced the highest levels of S- and RBD-binding antibodies and live Delta virus neutralization levels after one shot of immunization, while mice in the Delta + Alum vaccine group had the highest levels of these antibodies after two doses, and the Delta + MF59-like and Delta + Alum vaccine groups produced high levels of cross-neutralization antibodies against prototype, Beta, and Gamma strain SARS-CoV-2 viruses. There was no significant decrease in neutralizing antibody levels in any vaccine group during the observation period. CpG, MF59-like, and Alum adjuvant Delta strain inactivated SARS-CoV-2 vaccines excited different antibody subtypes compared with unadjuvanted vaccines; the Delta + CpG vaccine group had a higher proportion of IgG2b antibodies, indicating bias towards Th1 immunity. The proportions of IgG1 and IgG2b in the Delta + MF59-like vaccine group were similar to those of the unadjuvanted vaccine. However, the Delta + Alum vaccine group had a higher proportion of IgG1 antibodies, indicating bias towards Th2 immunity. Antigen-specific cytokine secretion CD4/8 T cells were analyzed. In conclusion, the results of this study show differences in the immune efficacy of CpG, MF59-like, and Alum adjuvant Delta strain inactivated SARS-CoV-2 vaccines in mice, which have significant implications for the selection strategy for vaccine adjuvants.