Development of an mRNA-LNP Vaccine against SARS-CoV-2: Evaluation of Immune Response in Mouse and Rhesus Macaque

Abstract

Among the vaccines have been developed thus far against SARS-CoV-2, the mRNA-based ones have demonstrated more promising results regarding both safety and efficacy. Two remarkable features of the mRNA vaccines introduced by the Pfizer/BioNTech and Moderna companies are the use of (N1-methyl-pseudouridine-) modified mRNA and the microfluidics-based production of lipid nanoparticles (LNPs) as the carrier. In the present study, except Anti-Reverse Cap Analog (ARCA), no other nucleoside analogs were employed to synthesize Spike-encoding mRNA using the in vitro transcription (IVT) method. Furthermore, LNPs were prepared via the ethanol injection method commonly used for liposome formation as an alternative for microfluidics-based approaches. The produced mRNA-LNP vaccine was evaluated for nanoparticles characteristics, encapsulation and transfection efficiencies, in vitro cytotoxicity as well as stability and storability. The safety of vaccine was assessed in Balb/c mice injected with mRNA-LNPs containing 10 µg of spike-encoding mRNA. Eventually, the vaccine efficacy in inducing an immune response against SARS-CoV-2 was studied in Balb/c and C57BL/6 mice (received either 1 or 10 µg of mRNA) as well as in rhesus macaque monkeys (infused with mRNA-LNPs containing 100 µg of mRNA). The ELISA and virus neutralizing test (VNT) results showed a significant augmentation in the level of neutralizing antibodies against SARS-CoV-2. Moreover, the ELISA assay showed virus-specific IFN-γ secretion in immunized mice as a marker of TH1 cell-based immune response, whereas favorably no change in the production of IL-4 was detected.

Polyethylene glycol (PEG) in mRNA-based COVID-19 vaccines: Impact, immunogenicity, and its potential role in post-vaccination induced hypersensitivity.

“…So, Abs that can bind to the S protein, mainly to its receptor-binding domain, can efficiently prevent the attachment of the virus to the host cells and protect them against viral infection. Based on previous knowledge, the S-protein is considered the main antigenic target for the development of vaccines against SARS-CoV-2 [37,38]. Based on SARS-CoV-2 platforms, there are more than 180 vaccine approaches under development against SARS-CoV-2 [39].…”

Beyond GalNAc! Drug delivery systems comprising complex oligosaccharides for targeted use of nucleic acid therapeutics

“…LNPs are now more commonplace as they have been specifically developed as a vector for gene therapy, 110 often targeting immune cells, 111,112 and use with siRNAs has been successful in silencing particular genes. 113 Moreover, Moderna Therapeutics and Pfizer/BioNTech recently succeeded in using LNPs as the delivery vector for the approved and globally used mRNA-based vaccines for SARS-CoV-2, 114,115 and could potentially revolutionise the future of vaccines for many diseases, including therapeutic mRNA delivery for diseases such as cystic fibrosis, where fractional amounts of correctly assembled proteins are considered sufficient for achieving therapy. There remain concerns though, around our continually increasing exposure to NPs such as those from combustion (CNPs) present in diesel exhaust fumes, and ENPs, including TiO 2 and carbon nanotubes.…”

How far are the new wave of mRNA drugs from us? mRNA product current perspective and future development

“…However, mRNA technology still needs to address the pain points of immunogenicity, efficiency in expressing proteins in vivo, and ultimately scale up production, so innovations in key development technologies such as sequence design, synthetic design of LNP delivery systems, and optimization of manufacturing processes could facilitate the development of mRNA drugs ( 61 ). mRNA design sequence optimization - both coding and non-coding sequences can be optimized ( 62 ). The translation efficiency of mRNAs can be improved by optimizing the coding sequence ( 63 ).…”