Antigen mRNA for Vaccines and Immunotherapy
mRNA offers several advantages over traditional plasmid and viral-based approaches:
- mRNA boasts a superior safety profile. As a transient carrier of genetic information, it is metabolized naturally and poses little to no risk of genomic integration. Additionally, no inactivated viruses or pathogens are needed.
- mRNA serves the dual purpose of expressing the desired antigen as well as acting as an adjuvant.
- mRNA triggers a more diverse immune response. Because the mRNA encoded epitopes are intracellular, they are recognized by the immune system in an MHC class-independent manner.
- mRNA can more readily transfect difficult-to-transfect cell types because it functions in the cytoplasm. DNA vaccines can be limited by lack of access to the nucleus.
- mRNA manufacturing is easily scalable. Because mRNA transcription is carried out completely in vitro, to hundreds of millions of vaccine doses with a lead time of as little as a few weeks. This allows for rapid deployment of a new antigen during pandemics.
- mRNA is easily customizable. The ease of manufacturing makes it a viable option for personalized treatments.
||TriLink’s custom mRNA transcription service includes an optional gene synthesis and cloning into our custom plasmid, designed for optimal stability and translation in mammalian systems. Milligram to gram scales, and grades from research to therapeutic GMP are available.
mRNA Vaccine Design
When designing an mRNA vaccine, several factors must be considered. mRNA is sensitive to nucleases and therefore needs to be delivered by a process that does not expose it significantly to nucleases, such as encapsulation with nanoparticles or delivery by electroporation (Brito et al., 2014, Geall et al., 2012). Intracellular stability is influenced by the design of the mRNA itself. An important element is the sequence of the 5′ and 3′ untranslated region (UTR), which dictates affinity to ribonucleases and proteins that promote or inhibit degradation. Another key element is the length of the poly(A) tail, which combats degradation from exonuclease activity (Pascolo, 2008, Ross, 1995).
mRNA vaccine efficacy is dependent on translation. And reports suggest translation efficiency may be altered by base modification. For example, transcripts made with 5-methyl-CTP, 2-Thio-UTP and Pseudo-UTP have enhanced translation in certain cell types. Importantly, these modifications also affect the immunogenicity of the mRNA (Kariko et al., 2008, Kormann et al., 2011). As with stability, the UTR and the poly(A) tail intrinsically affect translation through binding of various regulatory proteins (Wilkie et al., 2003, Munroe et al., 1990). And finally, a 5′cap is essential for translation. This can be added enzymatically or co-transcriptionally with Anti-Reverse Cap Analogue (ARCA) or mCAP.