A self-amplifying mRNA SARS-CoV-2 vaccine candidate induces safe and robust protective immunity in preclinical models.
Mol Ther
; 30(5): 1897-1912, 2022 05 04.
Article
in English
| MEDLINE | ID: covidwho-1586240
ABSTRACT
RNA vaccines have demonstrated efficacy against SARS-CoV-2 in humans, and the technology is being leveraged for rapid emergency response. In this report, we assessed immunogenicity and, for the first time, toxicity, biodistribution, and protective efficacy in preclinical models of a two-dose self-amplifying messenger RNA (SAM) vaccine, encoding a prefusion-stabilized spike antigen of SARS-CoV-2 Wuhan-Hu-1 strain and delivered by lipid nanoparticles (LNPs). In mice, one immunization with the SAM vaccine elicited a robust spike-specific antibody response, which was further boosted by a second immunization, and effectively neutralized the matched SARS-CoV-2 Wuhan strain as well as B.1.1.7 (Alpha), B.1.351 (Beta) and B.1.617.2 (Delta) variants. High frequencies of spike-specific germinal center B, Th0/Th1 CD4, and CD8 T cell responses were observed in mice. Local tolerance, potential systemic toxicity, and biodistribution of the vaccine were characterized in rats. In hamsters, the vaccine candidate was well-tolerated, markedly reduced viral load in the upper and lower airways, and protected animals against disease in a dose-dependent manner, with no evidence of disease enhancement following SARS-CoV-2 challenge. Therefore, the SARS-CoV-2 SAM (LNP) vaccine candidate has a favorable safety profile, elicits robust protective immune responses against multiple SARS-CoV-2 variants, and has been advanced to phase 1 clinical evaluation (NCT04758962).
Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
SARS-CoV-2
/
COVID-19
Type of study:
Experimental Studies
/
Prognostic study
Topics:
Vaccines
/
Variants
Limits:
Animals
/
Humans
Language:
English
Journal:
Mol Ther
Journal subject:
Molecular Biology
/
Therapeutics
Year:
2022
Document Type:
Article
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