The Firefly-Luciferase (F-Luc) circRNA expresses firefly luciferase protein, which is the enzyme for bioluminescence of fireflies and click beetles. This circRNA is generated via PIE- Self circularization and contains a small scar sequence. CVB3 IRES is designed in this circular RNA for initiating the IRES dependent ribosome recruiting and translation. All bases are non-modified. After efficient delivery into cells or animals, F-Luc circRNA can translate into F-Luc and emit bioluminescence in the presence of its substrate, Luciferin.