5-Methyl-CTP

5-Methyl-CTP is a modified nucleoside triphosphate, commonly used to substitute the naturally occurring cytidine triphosphate (CTP) during in vitro mRNA synthesis. Methylation of the cytosine C-5 position is a common, post-transcriptional modification for mRNA. Incorporation of chemically modified 5-methyl-CTP can increase mRNA stability and protein expression, and meanwhile, reduce interaction of innate immune receptors with in vitro-transcribed (IVT) mRNA. Apart from its application in encoding antigens for the activation of immune response against a variety of diseases such as COVID-19, IVT mRNA can also express the nanobody/variable domain of heavy chain of heavy-chain antibody targeting the intracellular components, enabling intracellular antigen labeling and manipulation. 

References:

1. Rahman MM, Zhou N, Huang J. An overview on the development of mRNA-based vaccines and their formulation strategies for improved antigen expression in vivo. Vaccines (Basel), 2021, 9(3): 244.

2. Lu J, Lu G, Tan S, et al. A COVID-19 mRNA vaccine encoding SARS-CoV-2 virus-like particles induces a strong antiviral-like immune response in mice. Cell Research, 2020, 30(10): 936-939.

3. Zhou X, Hao R, Chen C, et al. Rapid delivery of nanobodies/V_HH_s into living cells via expressing in vitro-transcribed mRNA. Molecular Therapy - Methods & Clinical Development, 2020, 17: 401-408.