Circular rna and preparation methods thereof

A pair of RNA molecules for making a circular RNA, comprising:

• (1) a first RNA molecule comprising the following elements operably connected and arranged in the order from the 5′-end to the 3′-end of the molecule:
• i) a 3′ intron sequence of a Group I intron,
• ii) a 3′ splice site of the Group I intron,
• iii) optionally, a 3′ exon sequence of the Group I intron,
• iv) an RNA sequence of interest,
• v) optionally, a 5′ exon sequence of the Group I intron,
• vi) a 5′ splice site of the Group I intron, and
• vii) a 5′ intron sequence of the Group I intron, and
• (2) a second RNA molecule comprising an intermediate intron sequence of the Group I intron,
• wherein when the first RNA molecule is contacted with the second RNA molecule, a scaffolding domain and a catalytic domain of the Group I intron are formed to thereby allow the production of the circular RNA comprising the 3′ exon sequence, the RNA sequence of interest and the 5′ exon sequence;
• and
• wherein the 3′ intron sequence comprises the R sequence and the S sequence of the Group I intron, the 5′ intron sequence comprises the internal guide sequence (IGS) and the P sequence of the Group I intron, and the intermediate intron sequence comprises the Q sequence of the Group I intron.