posted on 2022-02-02, 22:29authored byJian Wang, Xu-Guang Yin, Yu Wen, Jie Lu, Ru-Yan Zhang, Shi-Hao Zhou, Chun-Miao Liao, Hua-Wei Wei, Jun Guo
Safe and effective vaccines are the
best method to defeat worldwide
SARS-CoV-2 and its circulating variants. The SARS-CoV-2 S protein
and its subunits are the most attractive targets for the development
of protein-based vaccines. In this study, we evaluated three lipophilic
adjuvants, monophosphoryl lipid A (MPLA), Toll-like receptor (TLR)
1/2 ligand Pam3CSK4, and α-galactosylceramide
(α-GalCer), in liposomal and nonliposomal vaccines.
The immunological results showed that the MPLA-adjuvanted liposomal
vaccine induced the strongest humoral and cellular immunity. Therefore,
we further performed a systematic comparison of S-trimer, S-ECD, S1,
and RBD as antigens in MPLA-adjuvanted liposomes and found that, although
these four vaccines all induced robust specific antibody responses,
only S-trimer, S1, and RBD liposomes, but not S-ECD, elicited potent
neutralizing antibody responses. Moreover, RBD, S-trimer, and S1 liposomes
effectively neutralized variants (B.1.1.7/alpha, B.1.351/beta, P.1/gamma,
B.1.617.2/delta, and B.1.1.529/omicron). These results provide important
information for the subunit vaccine design against SARS-CoV-2 and
its variants.