Affiliation:
1. Department of Microbiology and Immunology, Medical School of Southeast University, Nanjing 210009, China
Abstract
The variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are more transmissible, with a reduced sensitivity to vaccines targeting the original virus strain. Therefore, developing an effective vaccine against both the original SARS-CoV-2 strain and its variants is an urgent need. It is known that the receptor-binding domain (RBD) in the S protein of SARS-CoV-2 is an important vaccine target, but subunit vaccines usually have lower immunogenicity and efficacy. Thus, selecting appropriate adjuvants to enhance the immunogenicity of protein-based subunit vaccine antigens is necessary. Here, an RBD-Fc subunit vaccine of SARS-CoV-2 has been generated, followed by vaccination in B6 mice, and four adjuvant regimens were investigated, including aluminum salts (Alum) + 3-O-desacyl-4′-monophosphoryl lipid A (MPL), AddaVax, QS21 + MPL, and Imiquimod. The adjuvant potency was evaluated by comparing the elicited polyclonal antibodies titers with measuring binding to RBD and S protein in ELISA and Western blot analysis, and also the cross-neutralizing antibodies titers using a pseudovirus infection assay of hACE2-expressing 293T cells, with pseudoviruses expressing the S protein of the SARS-CoV-2 original strain and Delta strain. The presence of QS21 + MPL adjuvant induced stronger polyclonal antibody response and neutralization potency blocking the original strain and Delta strain, as compared with the non-adjuvant RBD-Fc group and other adjuvant groups. Meanwhile, Imiquimod even had a negative effect in inducing specific antibodies and cross-neutralizing antibody production as an adjuvant.
Funder
National Nature Science Foundation of China
National Key Research and Development Plan of China
State Key Laboratory of Pathogen and Biosecurity
Subject
Pharmacology (medical),Infectious Diseases,Drug Discovery,Pharmacology,Immunology
Cited by
2 articles.
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