Fluorescent nucleobase analogue for cellular visualisation and regulation of immunostimulatory CpG oligodeoxynucleotides

Abstract

In this study, we explored the chemical modification of toll-like receptor 9 (TLR9) agonist DNA using a highly fluorescent thymine analogue, ^ThexT, focusing on its structural and photophysical characteristics. ^ThexT-labelled CpG oligonucleotides effectively demonstrated intracellular localisation within macrophage cell lines. Notably, immunostimulatory activity varied depending on the site of ^ThexT incorporation within the TLR9 agonist sequence. The introduction of fluorescent nucleobases offers a useful approach for visualising immunostimulatory oligonucleotides and for modulating immune responses.