Compositions and methods for producing circular polyribonucleotides

A linear polyribonucleotide having the formula 5′-(A)-(B)-(C)-(D)-(E)-(F)-(G)-3′, wherein:

• (A) comprises a 3′ portion of Group I catalytic intron fragment;
• (B) comprises a 3′ splice site;
• (C) comprises a 3′ exon fragment comprising a first annealing region comprising from 8 to 50 ribonucleotides, wherein the first annealing region is flanked on each side by a portion of the 3′ exon fragment, and wherein the 3′ exon fragment of (C) comprises the RNA equivalent of the sequence of
• (SEQ ID NO:
• 41)
• 5′-AAAATCCGTAGCGTCTAAACGGTCGTGTGGGTTCAAGTCCCTCCAC
• CCCCA-3′;
• (D) comprises a polyribonucleotide cargo;
• (E) comprises a 5′ exon fragment comprising a second annealing region comprising from 8 to 50 ribonucleotides that can hybridize to the first annealing region;
• (F) comprises a 5′ splice site;
• and (G) comprises a 5′ portion of Group I catalytic intron fragment, wherein the linear polyribonucleotide does not comprise a further annealing region comprising at least 6 ribonucleotides.